19p13.2

CKBBP2,CKbetaBP2,CRIF1,MRP-L59,PLINP,PLINP-1,PRG6,Plinp1

Various cancers

ovarian cancer, prostate cancer, thyroid cancer

GADD45GIP1 (CRIF1) may play a role in negative regulation of cell cycle progression and cell growth. Down-regulation of GADD45GIP1 (CRIF1) by siRNA induced inactivation of Rb and decreased cells in G1 phase (Chung et al., 2003). Expression of GADD45GIP1 is found to be down-regulated in several cancers including adrenal adenoma, papillary thyroid cancer, and ovarian cancer (Chung et al., 2003; Nakayama et al., 2007). Therefore, altered expression of GADD45GIP1 may contribute to tumorigenesis of some cell types.
More recently, CRIF1 was found to inhibit androgen receptor transactivation through direct physical interaction. Interestingly, CRIF1 represses AR transactivation both by outcompeting AR coactivators and by actively recruiting histone deacetylase (HDAC). Moreover, overexpression of CRIF1 decreases the mRNA level of AR-responsive gene and also inhibits the proliferation and cell cycle progression of prostate cancer cells. The data support the functional role of CRIF1 in prostatic cells (Suh et al., 2008).
Using serial analysis of gene expression, NAC1 was found to be significantly overexpressed in ovarian serous carcinomas (Nakayama et al., 2006). Immunohistochemical analysis of ovarian serous carcinomas localized NAC1 to discrete nuclear bodies, and the level of NAC1 expression was found to be correlated with tumor recurrence. Recently, GADD45GIP1 was identified as a NAC1- regulated gene (Nakayama et al., 2007). NAC-1 knockdown induced Gadd45GIP1 expression transcriptionally in both SKOV3 and HeLa cells; on the other hand, engineered expression of NAC-1 in NAC-1-negative RK3E and HEK293 cells suppressed endogenous Gadd45GIP1 expression. Furthermore, induced Gadd45GIP1 expression resulted in growth arrest in SKOV3 and HeLa cells both in vitro and in vivo, suggesting the tumor suppressor role of Gadd45GIP1.