Role In ccRCC Research Articles

PVHL/HIF-regulated CD70 expression is associated with infiltration of CD27+ lymphocytes and increased serum levels of soluble CD27 in clear cell renal cell carcinoma.

CD70, a member of the TNF ligand superfamily, has been shown frequently overexpressed in clear cell renal cell carcinoma (ccRCC). The mechanisms of CD70's upregulation and its role in ccRCC are unknown. CD70 expression was immunohistochemically analyzed in 667 RCCs and RCC metastases. Von Hippel-Lindau gene (VHL) mutations, expression patterns of VHL protein (pVHL), hypoxia-inducible factor (HIF) α, and several HIF targets were studied in tissues and cell lines and correlated with CD70 overexpression. Gene promoter analysis was performed to confirm CD70 as HIF target gene. Consecutive tissue sections were immunostained to reveal the relation between CD70-expressing RCCs and tumor-infiltrating lymphocytes positive for the CD70 receptor (CD27). CD70-mediated release of soluble CD27 in RCC was assessed by coculture experiments and sera analysis of patients with RCC. Elevated CD70 expression was seen in 80% of primary tumors and metastases of ccRCC and correlated with dysregulation of the pVHL/HIF pathway. In vitro analyses demonstrated that CD70 upregulation is driven by HIF. Furthermore, CD27(+) lymphocytes preferentially infiltrate CD70-expressing ccRCCs. CD70-dependent release of soluble CD27 in cocultures may explain the high CD27 levels observed in sera of patients with CD70-expressing ccRCC. The combination of lymphocyte infiltration and CD70 expression in RCC was associated with worse patient outcome. Our findings demonstrate that in ccRCC, CD70 expression is regulated by HIF as a consequence of pVHL inactivation. Increased serum levels of CD27 suggest the existence of CD70-expressing ccRCC, thus representing a potential serum marker for patients suffering from this disease.

Prognostic implication of TIM-3 in clear cell renal cell carcinoma

Clear cell renal carcinoma (ccRCC) is the most common tumor of the kidney.in adults. The prognosis of ccRCC remains unsatisfactory. Recently, T cell immunoglobulin mucin-3 (TIM-3), a novel transmembrane protein, has been implicated in tumor biology. Its role in ccRCC remains unknown. The aim of this study was to investigate the roles of TIM-3 as a prognostic marker in patients with ccRCC.TIM-3 protein expression was determined by immunohistochemistry and Western blot from 137 ccRCC tumor samples and adjacent normal renal tissues. We performed also the cell proliferation assay using 3-(4,5-dimethylthiazol -2yl)-2,5-diphenyl-2H tetrazolium bromide (MTT) and cell invasion assay. The effects of small interfering RNA (siRNA)-mediated knockdown of TIM-3 (TIM-3 siRNA) in two human ccRCC cell lines were evaluated. TIM-3 expression was higher in ccRCC tissue than in the adjacent normal renal tissue (P<0.001). High TIM-3 expression was an independent predictor of both cancer-specific survival and progression-free survival. TIM-3 protein was expressed in both ccRCC cell lines. Knockdown of TIM-3 suppressed the proliferation and invasion capacity of ccRCC cell lines.TIM-3 expression was associated with poor prognosis in ccRCC. Taken together, TIM-3 is a potential prognostic marker in ccRCC.

MicroRNA-187, down-regulated in clear cell renal cell carcinoma and associated with lower survival, inhibits cell growth and migration though targeting B7-H3

Aberrantly expressed microRNAs (miRNAs) are frequently associated with the aggressive malignant behavior of human cancers, including clear cell renal cell carcinoma (ccRCC). Based on the preliminary deep sequencing data, we hypothesized that miR-187 may play an important role in ccRCC development. In this study, we found that miR-187 was down-regulated in both tumor tissue and plasma of ccRCC patients. Lower miR-187 expression levels were associated with higher tumor grade and stage. All patients with high miR-187 expression survived 5years, while with low miR-187 expression, only 42% survived. Suppressed in vitro proliferation, inhibited in vivo tumor growth, and decreased motility were observed in cells treated with the miR-187 expression vector. Further studies showed that B7 homolog 3 (B7-H3) is a direct target of miR-187. Over-expression of miR-187 decreased B7-H3 mRNA level and repressed B7-H3-3′-UTR reporter activity. Knockdown of B7-H3 using siRNA resulted in similar phenotype changes as that observed for overexpression of miR-187. Our data suggest that miR-187 is emerging as a novel player in the disease state of ccRCC. miR-187 plays a tumor suppressor role in ccRCC.

MicroRNA-217, down-regulated in clear cell renal cell carcinoma and associated with lower survival, suppresses cell proliferation and migration

Aberrantly expressed microRNAs (miRNAs) are frequently correlated with a variety of human cancers, including clear cell renal cell carcinoma (ccRCC). In this study, we determined the expression patterns of miR-217 in ccRCC, and tested its effect on cancer cell proliferation and migration. The expression levels of miR-217 were determined in 54 ccRCC samples using Real-Time qPCR. 786-O and ACHN cells were transfected with miR-217 mimics or miRNA mimics control. Cell proliferation and migration were evaluated by MTT assay and scratch-wound assay, respectively. We found that miR-217 was down-regulated in ccRCC compared to paired normal tissue. Lower miR-217 expression levels were associated with higher tumor grade and stage. All patients with high miR-217 expression survived 5 years, while with low miR-217 expression, only 40% survived. Cell proliferation inhibition and decreased motility were observed in cells transfected with the miR-217 mimics. In conclusion, miR-217 plays a tumor suppressor role in ccRCC.

Tumor suppressive activity of prolyl isomerase Pin1 in renal cell carcinoma

Pin1 specifically recognizes and catalyzes the cis-trans isomerization of phosphorylated-Ser/Thr-Pro bonds, which modulate the stability, localization, and function of numerous Pin1 targets involved in tumor progression. However, the role of Pin1 in cancer remains enigmatic as the gene is located on chromosome 19p13.2, which is a region subject to loss of heterozygosity in several tumors. Since Pin1 protein is frequently under-expressed in kidney cancer, we have explored its role in human clear cell renal cell carcinoma (ccRCC). Here we show evidence for PIN1 gene deletion and mRNA under-expression as a mechanism of Pin1 reduction in ccRCC tumors. We demonstrate that restoration of Pin1 in cell lines found to be deficient in Pin1 protein expression can attenuate the growth of ccRCC cells in soft agar and a xenograft tumor model. Moreover, this ability of Pin1 to negatively influence tumor growth in ccRCC cells may be dependent on the presence of functional p53, which is infrequently mutated in ccRCC. These observations suggest Pin1 may have a mild tumor suppressive role in ccRCC.

Abstract 2806: Inactivation of PBRM1, a gene frequently mutated in clear cell renal carcinoma, suppresses tumor growth

Abstract The genetics of renal cancer is dominated by inactivation of the VHL tumour suppressor gene in clear cell renal carcinoma (ccRCC), the commonest histological subtype. However, our previous work has demonstrated that VHL loss alone is insufficient for ccRCC tumourigenesis arguing the need for additional genetic events. Recently, we have sequenced of the protein coding exome in 257 cases of primary renal carcinoma (RCC) and reported the identification of the SWI/SNF chromatin remodeling complex gene Polybromo 1 (PBRM1) as a second major RCC cancer gene with truncating mutations in 41% (85/257) of cases. In particular, all 9 cases with a SETD2 mutation have a mutation in either PBRM1 or VHL, with 7 of 9 cases having mutations in all three genes. The concomitant VHL, PBRM1 and SETD2 mutations, with all three genes mapping to chromosome 3p, suggest that the mutations are non-redundant functionally. To obtain further evidence that PBRM1 can act as a cancer gene, transcriptional profiling before and after PBRM1 knockdown was performed using gene expression microarrays. The results showed that PBRM1 activity regulates pathways associated with chromosomal instability and cellular proliferation. Consistently, knockdown of PBRM1 RNA resulted in a significant increase in proliferation 4/5 RCC lines. No effect was seen, however, in A704 cell, which carries a homozygous truncating PBRM1 mutation, confirming the specificity of the assay. Further, knockdown of PBRM1 resulted in significantly increased colony formation in soft-agar and increased cell migration indicative of an increase in transformed phenotype. Taken together, these data support PBRM1 having a tumor suppressor role in ccRCC. Therefore, understanding the contribution of PBRM1 mutation to clinical disease progression and outcome as well the potential for exploiting SWI/SNF complex abrogation therapeutically are important future areas of renal cancer research. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2806. doi:10.1158/1538-7445.AM2011-2806