3p21.31

CC-CKR-9,CDw199,GPR-9-6,GPR28

T-cell acute lymphocytic leukemia (T-ALL)

Qiuping et al. (2003) assessed the expression of CCR9 in 21 T-ALL and 17 "T-cell chronic lymphocytic leukemia" (T-CLL) cases, and found that functionally active CCR9 was selectively and frequently expressed on T-ALL CD4+ T cells and was moderately expressed on T-CLL CD4+ T cells.
Annels et al. (2004) investigated homing receptor expression on the blast cells of 11 pediatric T-ALL patients. They found that CCR9 and CD103 (alphaE integrin) were expressed at high levels on T-ALL cells of one patient. This patient later switched to a clonally related acute myeloid leukemia during treatment, and the relapse of leukemia was confined to the gut. This study suggests a role of CCR9 in infiltration of leukemic cells into the gut.

Adult T-cell leukemia (ATL)

ATL frequently invades the gastrointestinal tract. Nagakubo et al. (2007) examined CCR9 expression in five ATL-derived cell lines and 10 blood samples from ATL patients containing leukemic cells at high levels. Although all ATL cell lines were CCR9-positive, fresh ATL cells derived from patients were mostly negative. However, ATL cells became readily positive for CCR9 mRNA after one-day culture in parallel with the expression of Tax mRNA. This study suggests that CCR9 is inducible in ATL cells and may play a role in the high incidence of ATL cell invasion into the gastrointestinal tract.

Melanoma metastasis to the small intestine

Letsch et al. (2004) assessed CCR9 expression in 20 melanoma cell lines. The CCR9-positive cell lines were established from metastases to small intestine (n = 3), lymph node (n = 4), and skin (n = 1). Only melanoma cell lines derived from small intestinal metastases, however, were responsive to CCL25. This study correlated functional expression of CCR9 with melanoma metastasis to the small intestine.
Amersi et al. (2008) assessed CCR9 expression in primary (n = 23) and metastatic (n = 198) melanomas, and melanoma lines derived from small intestinal metastases (n = 8). CCR9 expression was observed in 88 of 102 metastatic melanomas from the small intestine, 8 of 8 melanoma lines derived from small intestine metastasis, but none of 96 metastatic melanomas from other sites. In addition, 11 of 23 primary melanomas were CCR9-positive and 7 of these later developed small intestinal metastases. This study suggests that CCR9 has a role in melanoma metastasis to the small intestine.

Melanoma metastasis

Seidl et al. (2007) investigated expression of eight chemokine receptors including CCR9 in 51 tissue samples of melanocytic origin. CCR9 mRNA was observed in more than half of the melanocytic lesions including lymph node metastases and visceral metastases. The authors concluded that there is no clear trend toward an association between the CCR9 expression levels and melanoma progression.

Prostate cancer metastasis

Singh et al. (2004) investigated CCR9 expression in two prostate cancer cell lines. Both cell lines expressed CCR9. This study suggests that expression and activation of CCR9 affect prostate cancer metastasis.

Small intestinal Crohns disease

Papadakis et al. (2001) found that CCR9+ T cells were markedly elevated in the peripheral blood of patients with Crohns disease but not those with purely colonic Crohns disease. This study suggests selective involvement of CCR9 in the pathogenesis of small bowel Crohns disease.