Identity

HGNC
LOCATION
19p13.13
LOCUSID
ALIAS
CRT,HEL-S-99n,RO,SSA,cC1qR

Abstract

Calreticulin (CALR) is a multifunctional protein involved in molecular chaperoning and calcium homeostasis. CALR has also been associated with proliferation, cell cycle progression, migration, invasion and anoikis resistance in cancer cells. The prognostic impact of CALR expression is yet to be elucidated, however in some types of cancer, high CALR expression has been related to worse clinical outcomes. Notably, the discovery of recurrent mutations in the exon 9 of the CALR gene in myeloproliferative neoplasms has opened a new round of investigations. The present review contains data on CALR DNA\/RNA, protein encoded and function.

DNA/RNA

Description

The entire CALR gene is approximately 5.9 Kb (start: 12938578 and end: 12944489 bp; orientation: Plus strand) and contains 9 exons. The CALR cDNA contains 1.9 Kb.

Proteins

Atlas Image
Figure 1. Schematic primary structure of CALR protein. The conserved P-domain, N-domain and C-domain and KDEL motif are illustrated. Amino acid (aa) positions are indicated.

Description

CALR protein consists of 417 aminoacids with a molecular weight of 46 kDa and has a conserved P-domain, N-domain and C-domain. A KDEL (lysine, aspartic acid, glutamic acid and leucine) motif, which prevent secretion from endoplasmic reticulum, this protein is found in the C-terminal region. The representation of the primary structure of CALR protein is illustrated in Figure 1.

Expression

Ubiquitous.

Localisation

CALR is predominantly found in the cytoplasm and endoplasmic reticulum. Nuclear, membrane and cell surface localization has also been frequently reported.

Function

CALR is a multifunctional protein, and molecular chaperoning and calcium homeostasis are the two most well-characterized functions of this protein. In the endoplasmatic reticulum, CALR binds to calcium, participates on folding of newly synthesized proteins and glycoproteins, and interacts with other chaperones as CANX (calnexin) (Gelebart, et al. 2005; Lu, et al. 2015; Zamanian, et al. 2013). Recently, evidence of the CALR participation in cell signaling networks has grown. CALR has been pointed out as a regulator of STAT3, STAT5, AKT, MAPK and PTK2 (FAK) cell signaling, promoting proliferation, cell cycle progression, migration, invasion and anoikis resistance (Chiang, et al. 2013; Du, et al. 2009; Feng, et al. 2015; Shi, et al. 2014; Wang, et al. 2013). CALR has also been described as a VEGFA and HIF1A inductor (Chen, et al. 2009; Weng, et al. 2015). Under stress conditions, CALR translocates onto the plasma membrane surface as a result of the CALR transport from endoplasmic reticulum to the Golgi apparatus, followed by exocytosis of CALR-containing vesicles, which acts as an "eat-me" signal (Zitvogel, et al. 2010). This process has been associated with immunogenic cell death (Apetoh, et al. 2007; Obeid, et al. 2007). In myeloproliferative neoplasms, mutated-CALR (exon 9 indel mutations) has been related to activation of MPL and JAK2 /STAT signaling, leading to cell proliferation and survival (Araki, et al. 2016; Balligand, et al. 2016; Chachoua, et al. 2016; Elf, et al. 2016; Marty, et al. 2016; Nivarthi, et al. 2016). A potential model for CALR network is summarized in Figure 2.
Atlas Image
Figure 2. A potential model for CALR network signaling. (Left panel) CALR binds to calcium, participates in the folding of newly synthesized glycoproteins, and interacts with other chaperones in the endoplasmatic reticulum. CALR regulates STAT3, STAT5, AKT, MAPK and FAK cell signaling, promoting proliferation, cell cycle progression, migration, invasion and anoikis resistance. Under stress condition, CALR translocates onto the plasma membrane by Golgi apparatus-mediated exocytosis, which participates in immunogenic cell death. (Right panel) Mutated-CALR (exon 9 indel mutations) induces activation of MPL and JAK2/STAT signaling, promoting cell proliferation and survival in myeloproliferative neoplasm cells. Abbreviations: ER, endoplasmic reticulum; Ca2+, calcium; MUT, mutated; P, phosphorylation. The Figure was produced using Servier Medical Art (http://www.servier.com/Powerpoint-image-bank).

Homology

CALR belongs to the calreticulin family, which is comprised of endoplasmic reticulum calcium-binding chaperones. CALR shares high homology among different species (Table 1).

Table 1. Comparative identity of human CALR and other species



% Identity for: Homo sapiens CALR

Symbol

Protein

DNA

vs. P. troglodytes

CALR

100

99.9

vs. M. mulatta

CALR

99.8

97.6

vs. C. lupus

CALR

96.6

90.6

vs. B. taurus

CALR

94.8

89.6

vs. M. musculus

Calr

95.7

88.2

vs. R. norvegicus

Calr

95.7

87.7

vs. G. gallus

CALR3

65.4

66.4

vs. X. tropicalis

calr

83.1

76.6

vs. D. rerio

Calrl2

80.0

73.7

vs. D. melanogaster

Crc

72.4

69.9

vs. A. gambiae

AgaP_AGAP004212

71.5

69.3

vs. C. elegans

crt-1

67.1

67.4

vs. A. thaliana

CRT1a

56.0

61.6

vs. A. thaliana

CRT1b

57.1

59.6

vs. O. sativa

Os03g0832200

56.5

62.9

vs. O. sativa

Os07g0246200

59.1

62.8


(Source: http://www.ncbi.nlm.nih.gov/homologene)

Mutations

Somatic

Mutations in exon 9 of the CALR gene have been described in 56 to 88% of non-mutated JAK2 and MPL myeloproliferative neoplasm (essential thrombocythemia and primary myelofibrosis) patients (Klampfl, et al. 2013; Nangalia, et al. 2013). Excluding myeloproliferative neoplasms, recurrent mutations in the CALR gene are rare. A total of 53 substitution missense, 7 substitution nonsense, 22 substitution synonymous, 798 insertion frameshift, 7 deletions inframe, 1493 deletion frameshift, 50 complex and 553 other mutations are reported in COSMIC, being 2939 mutations in hematopoietic and lymphoid cancers (Catalogue of somatic mutations in cancer; http://cancer.sanger.ac.uk/cancergenome/projects/cosmic).

Implicated in

Entity name
Myeloproliferative neoplasms
Note
In December 2013, two independent groups identified somatic mutations in the CALR gene in essential thrombocythemia and primary myelofibrosis patients with non-mutated JAK2 and MPL (Klampfl, et al. 2013; Nangalia, et al. 2013). CALR was also identified in a subset of patients with refractory anemia with ringed sideroblasts associated with marked thrombocytosis, but not in other hematological malignancies (Klampfl, et al. 2013). These finding were confirmed by several research groups (Grinsztejn, et al. 2016; Haslam, et al. 2016; Labastida-Mercado, et al. 2015; Li, et al. 2015; Lin, et al. 2015; Machado-Neto, et al. 2015; Monte-Mor, et al. 2016; Nunes, et al. 2015; Shirane, et al. 2015; Wojtaszewska, et al. 2015; Wu, et al. 2014). Over fifty different CALR mutations in exon 9 have been described, however the most frequent mutations (approximately 80%) are classified as type-1 (L367fs*46, deletion of 52bp) and type-2 (K385fs*47, insertion of 5bp). Patients with CALR-mutated myeloproliferative neoplasms have a lower age of disease onset, lower hemoglobin and platelet counts, and a better overall survival than either JAK2-mutated or CALR/JAK2/MPL wild-type patients (Chen, et al. 2014; Li, et al. 2014; Tefferi, et al. 2014b). In essential thrombocythemia, Pietra and colleagues (Pietra, et al. 2016) observed that CALR type 1-like mutations were mainly associated with a myelofibrosis phenotype and a higher risk of fibrotic transformation, whereas CALR type 2-like mutations were associated with an essential thrombocythemia phenotype, lower risk of thrombosis and an indolent clinical course. However, in primary myelofibrosis patients, CALR type 1-like mutations presented a better prognosis than patients with CALR type 2-like or JAK2 mutations (Guglielmelli, et al. 2015; Tefferi, et al. 2014a). CALR mutations were also reported in some cases of familial myeloproliferative neoplasms, but are rare in childhood essential thrombocythemia (Langabeer, et al. 2014; Lundberg, et al. 2014; Maffioli, et al. 2014). Gene expression signature studies on myeloproliferative neoplasm pathogenesis indicate a central role of the JAK/STAT signaling pathway in both JAK2 and CALR mutations, (Rampal, et al. 2014). Using a large panel of cancer cell lines, Kollmann and colleagues (Kollmann, et al. 2015) identified MARIMO as a leukemia cell line presenting a CALR mutation (61-bp deletion; c.1099_1159del; L367fs*43); surprisingly, this cell line showed neither JAK/STAT activation nor response to the treatment with the JAK1/2 inhibitor ruxolitinib.
Note
Balkhi and colleagues (Balkhi, et al. 2006) observed that CALR is acetylated in acute myeloid leukemia with t(8;21)(q22;q22). Previous studies also suggested that high CALR expression may be involved in repression of CEBPA in leukemia cells with inv(16) (p13q22) or t(8;21) (Helbling, et al. 2004; Helbling, et al. 2005). High CALR expression was observed in a subset of AML patients that are positive for XBP1s, a marker of unfolded protein response (Schardt, et al. 2009). Chemotherapy-independent CALR exposure at the cell surface was found in some acute myeloid leukemia patients, which was associated with low CD47 expression and enhanced cellular immune response against tumor antigens (Wemeau, et al. 2010). In samples from acute myeloid leukemia patients, CALR expression was increased in relation to samples from benign conditions, acute lymphoblastic leukemia and myeloproliferative neoplasms, however no association was observed with clinical and laboratorial characteristics (Park, et al. 2015).
Entity name
Chronic lymphocytic leukemia
Note
CALR is highly expressed by stromal cells, which participate in the protective effect that stroma exerts on chronic lymphocytic leukemia cells by B-cell antigen receptor stimulation (Binder, et al. 2010). Molica and colleagues (Molica, et al. 2016) reported similar concentrations of CALR in serum from chronic lymphocytic leukemia and from healthy donors. However, elevated serum CALR was associated with higher peripheral blood lymphocytosis, Rai sub stages I-II and shorter treatment-free survival.
Entity name
Lymphoma
Note
Vasostatin, a fragment of CALR (amino acids 1-180), was found to inhibit tumor formation capacity of the Burkitt lymphoma -cell line CA46 (Pike, et al. 1998). Similar results were found using a CALR fragment of amino acids 1-120 or 120-180 that also inhibits endothelial cell proliferation in vitro and Burkitt tumor growth (Pike, et al. 1999).
Entity name
Breast cancer
Note
Using two-dimensional gel electrophoresis, Franzen and colleagues (Franzen, et al. 1997; Franzen, et al. 1996) observed an increase of CALR expression in high proliferative lesions from breast carcinoma compared to fibroadenoma (benign tumor) cells. Similar findings were reported by other research groups (Bini, et al. 1997; Chahed, et al. 2005; Kabbage, et al. 2013; Song, et al. 2012; Zamanian, et al. 2016) that also observed high CALR expression in breast cancer samples compared to histologically normal tissues using proteomics analysis. CALR overexpression was also correlated with lymph node metastasis and with postoperative appearance of distant metastases in ERBB2 (Her2/neu) positive breast cancer (Eric, et al. 2009). A multivariate analysis indicated that CALR expression is an independent predictor of tumor size and the occurrence of distant metastasis in a cohort of 228 breast cancer patients (Lwin, et al. 2010). Abundant CALR protein was found in breast tumor interstitial fluid compared to normal breast interstitial fluid (Gromov, et al. 2010). Serum levels of IgA of anti-calreticulin antibodies were higher in breast cancer patients compared to healthy donors (Eric-Nikolic, et al. 2012). mRNA and protein CALR expression was found to be expressed at higher levels in the breast cancer MDA-MB-231 cell line (more aggressive model) compared to breast cancer MCF7 cell line (less aggressive model) (Lwin, et al. 2010). CALR-silenced MCF-7 cells presented lower migration and invasion, and global gene expression profiling indicated a participation of TP53 and MAPK signaling pathways in these processes (Zamanian, et al. 2016).
Entity name
Ovarian cancer
Note
Increased CALR expression, at the mRNA and protein levels, was observed in samples from ovarian cancer patients compared to samples from normal ovaries, benign tumors, and borderline tumors (Vera, et al. 2012). In ovarian cancer HOSE and A2780 cell lines, NGF (nerve growth factor) treatment resulted in induction of CALR expression, which was abolished by GW441756 treatment, a tropomyosin receptor kinase A selective inhibitor (Vera, et al. 2012). Overexpression of CALR was observed in solid metastases in comparison to effusions and primary ovarian carcinomas. High CALR expression in ovarian carcinoma effusions was associated with a better response to chemotherapy at diagnosis (Vaksman, et al. 2013).
Entity name
Prostate cancer
Note
n prostate cancer cell lines, CALR is a hormone responsive gene and CALR inhibition, by antisense oligonucleotide, increases the sensitivity to calcimycin (A23187)-induced apoptosis (Zhu, et al. 1999). Using two-dimensional gel, a high expression of CALR was found in prostate carcinoma compared to prostate hyperplasia (Alaiya, et al. 2000). On the other hand, Alur and colleagues (Alur, et al. 2009) observed that CALR is downregulated in cancer cells compared to adjacent benign glandular epithelial cells using immunohistochemical analysis. In the prostate cancer LNCaP cell line, induction of neuroendocrine differentiation reduces CALR expression and modulates intracellular Ca2+ homeostasis (Vanoverberghe, et al. 2004). In contrast, CALR was downregulated in poorly-differentiated tumors, though not in well-differentiated tumors in a murine prostate cancer model (Ruddat, et al. 2005). Increased CALR expression was observed in 1E8-H cells (prostate cancer cell line with high metastatic potential) compared to 2B4-L (prostate cancer cell line with low metastatic potential) (Wu, et al. 2007). In the human prostate cancer PC3 cell line, induction of CALR expression resulted in lower clonogenic capacity and xenograft tumor growth (Alur, et al. 2009). In rat Dunning AT3.1 prostate cancer cell line, induction of CALR overexpression did not modulate tumor growth, but reduced lung macrometastasis (Alur, et al. 2009). Docetaxel-resistant PC3 cells presented high levels of CALR compared to docetaxel-sensitive PC3 cells (Zu, et al. 2015).
Entity name
Bladder cancer
Note
Using proteomic analysis, Kageyama and colleagues (Kageyama, et al. 2004) reported an increased expression of CALR in bladder cancer compared to normal urothelium, and suggested that CALR may be a biomarker for bladder cancer with a sensitivity of 73% and a specificity of 86%. Latterly, the same research group led by Yoshiki (Iwaki, et al. 2004) validated these findings in a larger cohort of bladder cancer patients and controls (112 and 230, respectively), and CALR expression combined with other markers ( SNCG (synuclein gamma) and COMT (catechol-o-methyltransferase)) displayed a sensitivity of 76.8% and a specificity of 77.4% as bladder cancer biomarkers (CALR alone presented a sensitivity of 71.4% and a specificity of 77.8%). Yoshikis group (Kageyama, et al. 2009) also reported that CALR was highly expressed in urine samples from bladder urothelial carcinoma patients compared to urological patients without urothelial carcinoma and non-urological patients, and suggested that urinary CALR concentration may be a useful biomarker for bladder urothelial carcinoma with a sensitivity of 67.9% and specificity of 80.0%. In another study, urinary CALR was indicated as a potential biomarker for urothelial urinary bladder carcinoma (Soukup, et al. 2015). In the human bladder cancer J82 cell line, CALR silencing reduced cell viability, cell cycle progression, adhesion, migration, PXN (Paxillin)/FAK axis activation, FUT1 expression and in vivo tumor growth and metastasis (Lu, et al. 2014b; Lu, et al. 2011).
CALR expression was increased in urine from urothelial transitional cell carcinoma compared to healthy donors (Lu, et al. 2014a).
Entity name
Oral squamous cell carcinoma
Note
High prevalence of CALR expression positivity was observed in oral squamous cell carcinoma samples (96%) compared to non-cancerous matched tissue (32%). Similarly, oral squamous cell carcinoma cell lines (Ca9-22,CAL-27, HSC-3, SCC-9, SAS and FaDu) presented higher CALR expression than human oral keratinocytes (Chiang, et al. 2013). In SAS cells, CALR knockdown reduced cell proliferation, clonogenicity, anchorage-independent growth, migration, and Paxillin/FAK and MAPK activation (Chiang, et al. 2013).
Entity name
Esophageal squamous cell carcinoma
Note
CALR upregulation was observed in esophageal squamous cell carcinoma compared to adjacent nonmalignant tissue by two dimensional electrophoresis and mass spectrometry analysis (Jazii, et al. 2006; Nishimori, et al. 2006). In agreement, Du and colleagues (Du, et al. 2007) observed an increased CALR expression in esophageal squamous cell carcinoma samples compared to matched adjacent normal tissue, using two dimensional electrophoresis, western blot and/or immunohistochemistry, which was associated with a poorer prognosis by univariate analysis. Latterly, Du and colleagues (Du, et al. 2009), in an elegant mechanistic study, demonstrated that CALR inhibition reduced cell migration and invasion, clonogenic potential and in vivo tumor growth, and induced anoikis in esophageal squamous cell carcinoma cell lines. In the esophageal squamous cell carcinoma KYSE450 cells, CALR silencing reduces CTTN expression, and AKT and STAT3 activation (Du, et al. 2009). The same research group showed that CALR regulates PTPN1 (PTP1B) and NRP1 expression, at mRNA and protein levels, and STAT5 and ERK activation (Shi, et al. 2014; Wang, et al. 2013).
Entity name
Gastric cancer
Note
High CALR expression was observed in 20 out of 30 gastric cancer patients comparing matched tumor and non-tumor specimens (Chen, et al. 2009) using cDNA microarray (discovery cohort). Similar results were observed in an independent cohort of validation (enrolling 79 gastric cancer patients), in which high CALR expression was associated with high microvessel density, positive serosal invasion, lymph node metastasis, perineural invasion and poor survival (by multivariate analysis) (Chen, et al. 2009). Functional analysis using AGS human gastric cancer cell line denoted that CALR overexpression resulted in increased proliferation, cell cycle progression, migration and PIGF and VEGF secretion, whereas CALR inhibition resulted in the opposite effect (Chen, et al. 2009).
Entity name
Colorectal adenocarcinoma
Note
Using high-resolution two-dimensional gel analysis, CALR was found to be an abundant protein in the nuclear matrix of colon cancer cells, though not of normal colon tissue (Brunagel, et al. 2003). Low CALR expression was observed in colon cancer compared to normal colon tissue (Alfonso, et al. 2005; Toquet, et al. 2007). Similarly, Peng and colleagues (Peng, et al. 2010) observed reduced expression of CALR in colon tumors in relation to adjacent normal epithelium; of note, CALR expression was associated with T-cell infiltration and better survival rates in colon cancer patients by univariate analysis. CALR downregulation was also observed in colonic cancer cell lines (SW1116, SW620, SW480, HT29, HT29-Cl.19A, HT29-Cl.16E and Colo320 cells) compared to primary normal colonic epithelial cells (Toquet, et al. 2007). In contrast, Vougas and colleagues (Vougas, et al. 2008) reported high CALR expression in colon cancer compared to the matched mirror biopsy tissues, especially in highly malignant and poorly differentiated tumors.
In sera, anti-calreticulin antibodies were found in 57% of colorectal adenocarcinoma patients and in 2% of healthy donors (Pekarikova, et al. 2010). High MIR27A -expressing cells displayed less CALR on the cell surface (Colangelo, et al. 2016b), which impaired the kinetics of apoptosis in drug-induced immunogenic cell death of human colorectal cancer HCT116 cells (Colangelo, et al. 2016a).
Entity name
Hepatocellular carcinoma
Note
Yoon and colleagues (Yoon, et al. 2000) researching for nuclear matrix proteins differently expressed in hepatocellular carcinoma found CALR to be present in the nuclear matrix fraction of carcinomas, though not in the nonmalignant liver tissue. Increased CALR expression was also reported in the human hepatoma cell line BEL-7404 compared to normal human liver cell line L-02 (Yu, et al. 2000). The investigation of differentially expressed proteins in high (MHCC97-H) and low (MHCC97-L) metastatic hepatocellular carcinoma cell lines found that CALR is downregulated in high metastatic hepatocellular carcinoma MHCC97-H cell line compared to MHCC97-L cells (Ding, et al. 2004). CALR protein fragments were detected at higher levels in the serum from hepatocellular carcinoma patients in relation to the serum from healthy individuals, from chronic hepatitis patients, or from cirrhosis patients, suggesting that serum CALR fragments may be biomarkers for hepatocellular carcinoma (Chignard, et al. 2006). Serum anti-calreticulin antibodies have been found in 63% of hepatocellular carcinoma patients, suggesting that CALR is a molecular target for B cell molecular in this malignancy (Pekarikova, et al. 2010). In the hepatocellular carcinoma SMMC7721 and HepG2 cell lines, CALR silencing reduced cell viability, cell cycle progression, invasion and AKT activation (Feng, et al. 2015).
Entity name
Pancreatic adenocarcinoma
Note
Anti-calreticulin antibodies were found in 47% of sera from pancreatic adenocarcinoma patients compared to 2% from healthy donors (Pekarikova, et al. 2010). Higher CALR expression was found in pancreatic tumors in comparison to paired non-cancerous pancreatic ductal tissues, and was associated with more advanced lymph node metastasis, high grade stage and worse overall survival (by univariate analysis) (Sheng, et al. 2014). In pancreatic cancer cell lines, CALR silencing reduced proliferation, migration, ERK activation, and did not modulate TP53, MDM2 , phospho-AKT, phospho-JUNK and phospho-p38 MAPK, wheras CALR overexpression increased migration and ERK activation, but did not modulate TP53, MDM2 and phospho-AKT expression (Sheng, et al. 2014).
Xenograft pancreatic tumors treated with adenovirus expressing vasostatin presented lower tumor size and reduced angiogenesis compared to those treated with a control adenovirus (Li, et al. 2006). On the other hand, vasostatin-expressing BON cells, a pancreatic carcinoid tumor cell line, showed enhanced cell proliferation, invasion and in vivo tumor formation (Liu, et al. 2005). Using two-dimensional gel electrophoresis, increased CALR expression was observed in pancreatic cancer samples compared to matched non-cancerous pancreatic samples (Wang, et al. 2012), and in serum from pancreatic cancer patients compared to serum from healthy donors (Hong, et al. 2004).
Entity name
Lung cancer
Note
CARL protein levels were significantly higher in serum samples of lung cancer patients compared to healthy individuals. Immunohistochemistry analysis showed an increased CALR expression in lung cancer cells in comparison to normal lung cells, which was associated with tumor pathological grade (Liu, et al. 2012). In a large cohort of lung cancers (270 patients), CALR expression was heterogeneous, found in cytoplasm and at the surface of tumor cells and was not associated with tumor stage (Fucikova, et al. 2016). High CALR expression was associated with tumor infiltration by immune cells and low CALR expression impacted negatively on overall survival by univariate and multivariate analysis (Fucikova, et al. 2016). Pemetrexed-resistant A549 adenocarcinomic human alveolar basal epithelial cells presented elevated levels of CALR compared to pemetrexed-sensitive A549 cells. CALR silencing rescued, at least in part, sensibility to pemetrexed treatment in pemetrexed-resistant A549 cells, whereas induction of increased CALR expression reduced sensibility to pemetrexed treatment of pemetrexed-sensitive A549 cells (Chou, et al. 2015).
Entity name
Glioblastoma
Note
Okunaga and colleagues (Okunaga, et al. 2006) reported that the neuroglioma H4 cell line (radiosensitive cells) expressed high levels of CALR compared to the glioblastoma cell lines U251MG and T98G (radioresistant cells). The authors also observed that the induction of CALR expression by transfection enhanced radiation-produced apoptosis in U251MG cells (Okunaga, et al. 2006). In glioma patients, CALR expression was reduced compared to normal brain tissue, and negative CALR expression was associated with higher grade disease and reduced overall survival by univariate analysis (Gao, et al. 2013). CALR expression was increased in 5 out of 9 relapsed glioblastoma patients that presented low levels of CALR expression(Muth, et al. 2016).
Entity name
Neuroblastoma
Note
Using immunohistochemical, Hsu and colleagues (Hsu, et al. 2005) observed that 47% of neuroblastoma samples were positive for CALR expression, which associated with age at diagnosis ≤1 year, early clinical stage, differentiated tumors and non-amplified MYCN. The authors also showed that positive CALR expression was an independent factor for better overall survival by multivariable analysis (Hsu, et al. 2005). In neuroblastoma cell lines (SH-SY5Y, SK-N-DZ and stNB-V1), CALR inhibition resulted in VEGFA and HIF1A downregulation, whereas CALR overexpression led to increased levels of VEGFA and HIF1A (Weng, et al. 2015).
Entity name
Melanoma
Note
Increased CALR expression was found upon ionizing radiation and associated with radio resistance of the melanoma cell line SQ-20B (Ramsamooj, et al. 1995). In melanoma samples, a similar profile of CALR expression was observed between primary tumors and metastatic lesions (Dissemond, et al. 2004). Using a proteomic approach, a higher CALR expression was observed in the melanoma 526 cell line compared to melanocytes (FOM78) (Caputo, et al. 2011).
Entity name
Liposarcoma
Note
CALR was expressed in both dedifferentiated areas and atypical stromal cells and/or lipoblasts in the well-differentiated areas in liposarcomas, thought not in normal fat tissue (Hisaoka, et al. 2012). The authors associated CALR upregulation with the downregulation of MIR1275 , a putative microRNA that targets CALR. In addition, CALR silencing reduces cell proliferation and induces adipogenesis in the dedifferentiated liposarcoma FU-DDLS-1 cell line (Hisaoka, et al. 2012).
Entity name
Fibrosarcoma
Note
Using fibrosarcoma murine cell line models that present regressive (QR-32 cells) and progressive (QRsP-11 cells) tumor formation in mice, Hayashi and colleagues reported that QRsP-11 cells presented higher expression of CALR compared to QR-32 cells (Hayashi, et al. 2005).
Entity name
Thyroid cancer
Note
Thyroid cell lines transformed by mutant TP53 presented CALR downregulation (Paron, et al. 2005). CALR expression was found to be lower in malignant follicular thyroid carcinoma compared with benign follicular thyroid adenoma using proteomics analysis validated by immunohistochemistry (Netea-Maier, et al. 2008).
Entity name
Adrenocortical carcinomas
Note
Elevated CALR expression was identified in adrenocortical carcinomas compared to adjacent normal adrenocortical tissues, which was associated with higher grade tumors (Yang, et al. 2013).
Entity name
Pituitary adenoma
Note
Desiderio and Zhan (Desiderio, et al. 2003), using proteomics approaches, found CALR to be a differently expressed protein in pituitary adenoma compared to control tissue.

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153263102004The leukemic fusion gene AML1-MDS1-EVI1 suppresses CEBPA in acute myeloid leukemia by activation of Calreticulin.Helbling D et al
224299662012Aberrant calreticulin expression is involved in the dedifferentiation of dedifferentiated liposarcoma.Hisaoka M et al
152893612004An autoantibody-mediated immune response to calreticulin isoforms in pancreatic cancer.Hong SH et al
156682902005Calreticulin expression in neuroblastoma--a novel independent prognostic factor.Hsu WM et al
155960442004Diagnostic potential in bladder cancer of a panel of tumor markers (calreticulin, gamma -synuclein, and catechol-o-methyltransferase) identified by proteomic analysis.Iwaki H et al
171314712006Identification of squamous cell carcinoma associated proteins by proteomics and loss of beta tropomyosin expression in esophageal cancer.Jazii FR et al
233349572013Calreticulin expression in infiltrating ductal breast carcinomas: relationships with disease progression and humoral immune responses.Kabbage M et al
147646412004Identification by proteomic analysis of calreticulin as a marker for bladder cancer and evaluation of the diagnostic accuracy of its detection in urine.Kageyama S et al
252490122015MARIMO cells harbor a CALR mutation but are not dependent on JAK2/STAT5 signaling.Kollmann K et al
256376892015The mutation profile of JAK2, MPL and CALR in Mexican patients with Philadelphia chromosome-negative myeloproliferative neoplasms.Labastida-Mercado N et al
245232262014CALR mutations are rare in childhood essential thrombocythemia.Langabeer SE et al
249971522014Calreticulin mutations in Chinese with primary myelofibrosis.Li B et al
162879012006Treatment of pancreatic carcinoma by adenoviral mediated gene transfer of vasostatin in mice.Li L et al
257463032015Frequency and allele burden of CALR mutations in Chinese with essential thrombocythemia and primary myelofibrosis without JAK2(V617F) or MPL mutations.Li N et al
260714742015The Prevalence of JAK2, MPL, and CALR Mutations in Chinese Patients With BCR-ABL1-Negative Myeloproliferative Neoplasms.Lin Y et al
162939702005Gene transfer of vasostatin, a calreticulin fragment, into neuroendocrine tumor cells results in enhanced malignant behavior.Liu M et al
220833472012Calreticulin as a potential diagnostic biomarker for lung cancer.Liu R et al
248848142014A panel of tumor markers, calreticulin, annexin A2, and annexin A3 in upper tract urothelial carcinoma identified by proteomic and immunological analysis.Lu CM et al
217232452011Changes in tumor growth and metastatic capacities of J82 human bladder cancer cells suppressed by down-regulation of calreticulin expression.Lu YC et al
259187162015Functional roles of calreticulin in cancer biology.Lu YC et al
247645622014Somatic mutations in calreticulin can be found in pedigrees with familial predisposition to myeloproliferative neoplasms.Lundberg P et al
208342372010Clinicopathological significance of calreticulin in breast invasive ductal carcinoma.Lwin ZM et al
260414262015Somatic mutations of calreticulin in a Brazilian cohort of patients with myeloproliferative neoplasms.Machado-Neto JA et al
244412912014Looking for CALR mutations in familial myeloproliferative neoplasms.Maffioli M et al
266083312016Calreticulin mutants in mice induce an MPL-dependent thrombocytosis with frequent progression to myelofibrosis.Marty C et al
267281202016Serum levels of soluble calreticulin predict for time to first treatment in early chronic lymphocytic leukaemia.Molica S et al
269949602016Clinical features of JAK2V617F- or CALR-mutated essential thrombocythemia and primary myelofibrosis.Monte-Mor Bda C et al
266463112016Primary glioblastoma multiforme tumors and recurrence : Comparative analysis of the danger signals HMGB1, HSP70, and calreticulin.Muth C et al
243253592013Somatic CALR mutations in myeloproliferative neoplasms with nonmutated JAK2.Nangalia J et al
183166232008Discovery and validation of protein abundance differences between follicular thyroid neoplasms.Netea-Maier RT et al
164006902006Proteomic analysis of primary esophageal squamous cell carcinoma reveals downregulation of a cell adhesion protein, periplakin.Nishimori T et al
268835792016Thrombopoietin receptor is required for the oncogenic function of CALR mutants.Nivarthi H et al
262278532015CALR mutations screening in wild type JAK2(V617F) and MPL(W515K/L) Brazilian myeloproliferative neoplasm patients.Nunes DP et al
171870722007Calreticulin exposure dictates the immunogenicity of cancer cell death.Obeid M et al
169511812006Calreticulin, a molecular chaperone in the endoplasmic reticulum, modulates radiosensitivity of human glioblastoma U251MG cells.Okunaga T et al
266402262015Calreticulin mRNA expression and clinicopathological characteristics in acute myeloid leukemia.Park S et al
156918882005A differential proteomic approach to identify proteins associated with thyroid cell transformation.Paron I et al
200306682010Calreticulin is a B cell molecular target in some gastrointestinal malignancies.Pekáriková A et al
204805312010Expression of calreticulin is associated with infiltration of T-cells in stage IIIB colon cancer.Peng RQ et al
264496622016Differential clinical effects of different mutation subtypes in CALR-mutant myeloproliferative neoplasms.Pietra D et al
98585211998Vasostatin, a calreticulin fragment, inhibits angiogenesis and suppresses tumor growth.Pike SE et al
247408122014Integrated genomic analysis illustrates the central role of JAK-STAT pathway activation in myeloproliferative neoplasm pathogenesis.Rampal R et al
76067211995Enhanced expression of calreticulin in the nucleus of radioresistant squamous carcinoma cells in response to ionizing radiation.Ramsamooj P et al
156663622005Evidence for downregulation of calcium signaling proteins in advanced mouse adenocarcinoma.Ruddat VC et al
194707302009Activation of the unfolded protein response is associated with favorable prognosis in acute myeloid leukemia.Schardt JA et al
230196532012An immunosurveillance mechanism controls cancer cell ploidy.Senovilla L et al
242648002014Overexpression of calreticulin contributes to the development and progression of pancreatic cancer.Sheng W et al
252314042014Calreticulin promotes migration and invasion of esophageal cancer cells by upregulating neuropilin-1 expression via STAT5A.Shi F et al
253988332015JAK2, CALR, and MPL mutation spectrum in Japanese patients with myeloproliferative neoplasms.Shirane S et al
231391372012Proteomic analysis of breast cancer tissues to identify biomarker candidates by gel-assisted digestion and label-free quantification methods using LC-MS/MS.Song MN et al
256623372015Panel of Urinary Diagnostic Markers for Non-Invasive Detection of Primary and Recurrent Urothelial Urinary Bladder Carcinoma.Soukup V et al
244021622014CALR vs JAK2 vs MPL-mutated or triple-negative myelofibrosis: clinical, cytogenetic and molecular comparisons.Tefferi A et al
173900512007Altered Calreticulin expression in human colon cancer: maintenance of Calreticulin expression is associated with mucinous differentiation.Toquet C et al
240600042013Calreticulin expression is reduced in high-grade ovarian serous carcinoma effusions compared with primary tumors and solid metastases.Vaksman O et al
146851642004Ca2+ homeostasis and apoptotic resistance of neuroendocrine-differentiated prostate cancer cells.Vanoverberghe K et al
227733722012Nerve growth factor induces the expression of chaperone protein calreticulin in human epithelial ovarian cells.Vera C et al
184047952008Two-dimensional electrophoresis and immunohistochemical study of calreticulin in colorectal adenocarcinoma and mirror biopsies.Vougas K et al
238140252013PTP1B contributes to calreticulin-induced metastatic phenotypes in esophageal squamous cell carcinoma.Wang XM et al
229407242012Proteomic differential display identifies upregulated vinculin as a possible biomarker of pancreatic cancer.Wang Y et al
213688772010Calreticulin exposure on malignant blasts predicts a cellular anticancer immune response in patients with acute myeloid leukemia.Wemeau M et al
252881512015Calreticulin Regulates VEGF-A in Neuroblastoma Cells.Weng WC et al
253237792015Frequency and molecular characteristics of calreticulin gene (CALR) mutations in patients with JAK2 -negative myeloproliferative neoplasms.Wojtaszewska M et al
175669732007Proteome analysis of human androgen-independent prostate cancer cell lines: variable metastatic potentials correlated with vimentin expression.Wu M et al
250238982014The mutation profile of JAK2 and CALR in Chinese Han patients with Philadelphia chromosome-negative myeloproliferative neoplasms.Wu Z et al
235873572013A comparative proteomic study identified calreticulin and prohibitin up-regulated in adrenocortical carcinomas.Yang MS et al
107061332000Nuclear matrix of calreticulin in hepatocellular carcinoma.Yoon GS et al
110013232000Identification of differentially expressed proteins between human hepatoma and normal liver cell lines by two-dimensional electrophoresis and liquid chromatography-ion trap mass spectrometry.Yu LR et al
233928432013Calreticulin and cancer.Zamanian M et al
102134981999Calreticulin expression is associated with androgen regulation of the sensitivity to calcium ionophore-induced apoptosis in LNCaP prostate cancer cells.Zhu N et al
204214322010Immunogenic tumor cell death for optimal anticancer therapy: the calreticulin exposure pathway.Zitvogel L et al
259993652015Evaluation of Docetaxel-Sensitive and Docetaxel-Resistant Proteomes in PC-3 Cells.Zu S et al

Other Information

Locus ID:

NCBI: 811
MIM: 109091
HGNC: 1455
Ensembl: ENSG00000179218

Variants:

dbSNP: 811
ClinVar: 811
TCGA: ENSG00000179218
COSMIC: CALR

RNA/Proteins

Gene IDTranscript IDUniprot
ENSG00000179218ENST00000316448P27797
ENSG00000179218ENST00000316448V9HW88
ENSG00000179218ENST00000586760K7EL50
ENSG00000179218ENST00000586967K7ELE2
ENSG00000179218ENST00000588454K7EJB9

Expression (GTEx)

0
500
1000
1500
2000
2500

Pathways

PathwaySourceExternal ID
Antigen processing and presentationKEGGko04612
Antigen processing and presentationKEGGhsa04612
Chagas disease (American trypanosomiasis)KEGGko05142
Chagas disease (American trypanosomiasis)KEGGhsa05142
PhagosomeKEGGko04145
PhagosomeKEGGhsa04145
Protein processing in endoplasmic reticulumKEGGko04141
Protein processing in endoplasmic reticulumKEGGhsa04141
HTLV-I infectionKEGGko05166
HTLV-I infectionKEGGhsa05166
Metabolism of proteinsREACTOMER-HSA-392499
Post-translational protein modificationREACTOMER-HSA-597592
Asparagine N-linked glycosylationREACTOMER-HSA-446203
N-glycan trimming in the ER and Calnexin/Calreticulin cycleREACTOMER-HSA-532668
Calnexin/calreticulin cycleREACTOMER-HSA-901042
Unfolded Protein Response (UPR)REACTOMER-HSA-381119
ATF6 (ATF6-alpha) activates chaperonesREACTOMER-HSA-381033
ATF6 (ATF6-alpha) activates chaperone genesREACTOMER-HSA-381183
DiseaseREACTOMER-HSA-1643685
Infectious diseaseREACTOMER-HSA-5663205
Influenza InfectionREACTOMER-HSA-168254
Influenza Life CycleREACTOMER-HSA-168255
Virus Assembly and ReleaseREACTOMER-HSA-168268
Assembly of Viral Components at the Budding SiteREACTOMER-HSA-168316
Immune SystemREACTOMER-HSA-168256
Adaptive Immune SystemREACTOMER-HSA-1280218
Class I MHC mediated antigen processing & presentationREACTOMER-HSA-983169
Antigen Presentation: Folding, assembly and peptide loading of class I MHCREACTOMER-HSA-983170
Antigen processing-Cross presentationREACTOMER-HSA-1236975
ER-Phagosome pathwayREACTOMER-HSA-1236974
Vesicle-mediated transportREACTOMER-HSA-5653656
Binding and Uptake of Ligands by Scavenger ReceptorsREACTOMER-HSA-2173782
Scavenging by Class A ReceptorsREACTOMER-HSA-3000480
Scavenging by Class F ReceptorsREACTOMER-HSA-3000484

Protein levels (Protein atlas)

Not detected
Low
Medium
High

References

Pubmed IDYearTitleCitations
243253562013Somatic mutations of calreticulin in myeloproliferative neoplasms.432
243253592013Somatic CALR mutations in myeloproliferative neoplasms with nonmutated JAK2.406
211781372010Calreticulin is the dominant pro-phagocytic signal on multiple human cancers and is counterbalanced by CD47.194
244807822014Radiation-induced immunogenic modulation of tumor enhances antigen processing and calreticulin exposure, resulting in enhanced T-cell killing.117
243663622014JAK2 or CALR mutation status defines subtypes of essential thrombocythemia with substantially different clinical course and outcomes.112
244021622014CALR vs JAK2 vs MPL-mutated or triple-negative myelofibrosis: clinical, cytogenetic and molecular comparisons.109
199131212009Gene-centric association signals for lipids and apolipoproteins identified via the HumanCVD BeadChip.85
266681332016Thrombopoietin receptor activation by myeloproliferative neoplasm associated calreticulin mutants.80
233649152013Chemotherapy-induced immunogenic modulation of tumor cells enhances killing by cytotoxic T lymphocytes and is distinct from immunogenic cell death.77
243712112014Impact of calreticulin mutations on clinical and hematological phenotype and outcome in essential thrombocythemia.76

Citation

Joao Agostinho Machado-Neto ; Paula de Melo Campos ; Fabiola Traina

CALR (calreticulin)

Atlas Genet Cytogenet Oncol Haematol. 2016-08-01

Online version: http://atlasgeneticsoncology.org/gene/904/calr