17q21.33

PPP1R6,PPP1R9,SPINO,Spn

Various cancers

Expression levels decrease in some carcinomas.

PPP1R9B mRNA is lost in a percentage of renal carcinomas and lung adenocarcinomas (Carnero, 2012). More interestingly, analysis of normal vs tumoral samples of tumors of the CNS showed clear downregulation of PPP1R9B in tumoral samples. Furthermore, lower levels of PPP1R9B mRNA correlates with higher grade of ovarian carcinoma and chronic myelogenous leukaemia (Carnero, 2012). PPP1R9B is also lost in 20% and reduced in another 37% of human lung tumors (Molina-Pinelo et al., 2011). PPP1R9B reduction correlates with malignant grade and p53 mutations (Carnero, 2012).
The PPP1R9B gene is located in chromosome 17, at position 17q21.33, and in a cytogenetic area frequently associated with microsatellite instability and loss of heterozygosity. This region is comprised of a relatively high density of tumor suppressor genes, including known (BRCA1, NME1), putative (JUP, prohibitin), and unidentified candidates distal to the BRCA1 locus (Carnero, 2012).
Most of the studies on the 17q21 locus have focused on BRCA1, which exhibits a variable frequency in LOH depending on the type of tumor, stage and marker employed, and has been extensively studied in breast carcinomas (Caduff et al., 1999; Maitra et al., 1999; Querzoli et al., 2001). However, there are few studies that suggest the existence of unknown tumor suppressor genes for breast tumors in an area that includes the locus of PPP1R9B. LOH in chromosome 17q21.3 has been observed in different tumors, including breast, ovarian, prostate, colorectal, gastric, renal and lung carcinomas, as well as in salivary gland carcinosarcoma, an extremely aggressive neoplasm (Caduff et al., 1999; Maitra et al., 1999; Querzoli et al., 2001).
The markers used in some of these studies with no linkage to BRCA1 point to NME1 as a tumor suppressor gene candidate to justify the functional impact of the allelic loss. However, in different LOH studies an unidentified tumor suppressor gene nearby NME1 has been proposed. PPP1R9B is located in close proximity to NME1, at only 1 Mb, probably sharing the allelic loss in these studies.
The most relevant data according to PPP1R9B LOH came from a study on primary lung carcinoma (Abujiang et al., 1998). This group performed an extensive LOH mapping in human lung cancers, using 15 highly polymorphic markers, 7 of which span 17q11-24 region. The higher LOH value appeared with the D17S588 marker, showing a 53% of loss. The D17S588 marker locates exactly within the PPP1R9B locus. These data provided the first robust data implicating PPP1R9B LOH in cancer. Closer tumor suppressor genes, such as BRCA1, were not seriously affected (6-13% LOH), nor other lung proliferative pathologies (squamous cell carcinoma and small cell carcinoma only showed minimal LOH, below 14%, for both PPP1R9B and BRCA1 markers).
Several genetic linkage studies using the marker D17S588 have suggested the existence of a tumor suppressor gene distal to BRCA1 (Porter et al., 1993; Porter et al., 1994). The maximum LOD scores obtained for D17S588 were of 5,44 in an Edinburgh study of 15 families (Cohen et al., 1993) and 21,68 in an analysis of 271 breast and breast-ovarian cancer families (Easton et al., 1993, Smith et al., 1993), indicating the importance of this locus in the pathology of cancer. The D17S588 marker lies inside the PPP1R9B gene.
Another study that investigated the correlation between p53 abnormalities and allelic loss of BRCA1, BRCA2 and adjacent loci in breast cancer found a strong correlation when using the D17S588 marker (Querzoli et al., 2001; Tseng et al., 1997). Again, PPP1R9B may be involved in the tumorigenic process by functioning, in association with a loss of p53 functionality, as a tumor suppressor (47,1% LOH) (Tseng et al., 1997).

Learning and memory, regulation of blood pressure and cardiac function

Learning and memory defects, problems in the regulation of blood pressure and cardiac function, tumors of different origin.