Dicer is down-regulated in clear cell renal cell carcinoma and in vitro Dicer knockdown enhances malignant phenotype transformation.

Although emerging evidence has shown that the deregulation of micro-ribonucleic acid (RNA) biogenesis machinery is involved in various human malignancies, this role has not been investigated in clear cell renal cell carcinoma (ccRCC). This study aims to determine whether Dicer, a key enzyme responsible for biogenesis of microRNA, is deregulated in ccRCC. The biological roles of Dicer in vitro are also determined. The expression of Dicer at messenger RNA and protein levels was detected by real-time quantitative polymerase chain reaction and western blot, respectively, in human kidney tubule epithelial cell line, nonmetastatic 786-O ccRCC cell line, and metastatic ACHN ccRCC cell line, as well as in 42 cases of ccRCC surgical specimens including 14 cases with distant metastasis and their corresponding adjacent normal renal tissues. Dicer expression levels in specimens were also measured by immunohistochemical staining. Knockdown of Dicer expression in 786-O and ACHN ccRCC cell lines was achieved by transfecting short interfering RNA against Dicer. The effects of Dicer on cell proliferation, migration, and invasion were detected by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay, flow cytometric analyses, and Boyden chamber Transwell assay, respectively. Compared with human kidney tubule epithelial cell line, Dicer expression levels were significantly down-regulated in 786-O and ACHN ccRCC cell lines, with the metastatic ACHN ccRCC cell line having even lower levels. Meanwhile, Dicer expression levels were significantly down-regulated in ccRCC surgical specimens compared with adjacent normal renal tissues, with the metastatic ones further reduced, and Dicer messenger RNA levels were significantly correlated with overall tumor-node-metastasis stage of ccRCC. In vitro, the knockdown of Dicer significantly promoted cell proliferation, migration, and invasion. Reduced expression of Dicer may play a role in the tumorigenesis of ccRCC and further decline may be associated with distant metastasis of ccRCC.

Ma X ，Fan Y ，Gao Y ，Zhang Y ，Huang Q ，Ai Q ，Ni D ，Chen W ，Zhang P ，Song E ，Wang B ，Shi T ，Zheng T ，Zhang X ... -  《-》

hZIP1 that is down-regulated in clear cell renal cell carcinoma is negatively associated with the malignant potential of the tumor.

The human ZRT, IRT-like protein 1 (hZIP1) has been associated with tumorigenesis. However, its role in clear cell renal cell carcinoma (ccRCC) has not been yet reported. The objective was to investigate hZIP1 expression in ccRCC and its association with clinicopathological features. A total of 106 ccRCC tissue samples and corresponding normal kidney tissue samples were examined, along with 3 ccRCC cell lines (ACHN, 769-P, and 786-O). Real-time polymerase chain reaction, Western blot, and immunohistochemistry were used to investigate the expression of hZIP1 and its relationship with clinicopathological features. The ACHN cell line, exhibiting the highest hZIP1 expression, was transfected with hZIP1 small interfering RNA or mock small interfering RNA. Cellular proliferation was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Invasion was determined by Transwell assay. The level of hZIP1 was decreased in ccRCC tissues when compared with normal tissues. hZIP1 expression significantly decreased with increasing clinical stage and pathological grade in ccRCC samples (P<0.05), showing a significant negative correlation with the histological grade (P<0.05). High hZIP1 expression was associated with a better disease-free survival (P<0.01). Silencing of hZIP1 expression enhanced the proliferative and invasive abilities of ACHN cells. Results suggest that hZIP1 may act as a tumor suppressor in ccRCC. hZIP1 is closely correlated with clinicopathological features. High hZIP1 expression may be an indicator of good prognosis in ccRCC.

Dong X ，Kong C ，Zhang Z ，Liu X ，Zhan B ，Chen Z ，Shi D ... -  《-》

Hypoxia-induced overexpression of stanniocalcin-1 is associated with the metastasis of early stage clear cell renal cell carcinoma.

Ma X ，Gu L ，Li H ，Gao Y ，Li X ，Shen D ，Gong H ，Li S ，Niu S ，Zhang Y ，Fan Y ，Huang Q ，Lyu X ，Zhang X ... -  《Journal of Translational Medicine》

Down-regulation of CD74 inhibits growth and invasion in clear cell renal cell carcinoma through HIF-1α pathway.

To investigate the expression and function of CD74 in normal renal tissue and clear cell-renal cell carcinoma (ccRCC), as well as related renal tubule epithelial lines. We also analyzed the association between clinicopathological characteristics of ccRCCs and the expression levels of CD74. Immunostaining of CD74 was performed in 107 patients' renal tissue and cell lines. We evaluated the association between clinicopathological characteristics of ccRCC and CD74 levels using image analysis. CD74 expression levels were also analyzed by Western blot. Lentivirus-mediated CD74 knockdown inhibited the growth and invasion, of ccRCC cell lines 786-O in vitro and in vivo. Cell proliferation, apoptosis, and invasion as well as HIF-1α pathway-related proteins, were estimated by Western blot. All experiments were repeated at least 3 times. Immunostaining and image analysis showed strong immunoreactions of CD74 in all patients' ccRCC tissue and malignant cell lines, while CD74 expression levels were associated with tumor grade (P = 0.013). Western blot indicated that ccRCC tissue and malignant cell lines expressed higher levels of CD74 and hypoxia inducible factor 1α (HIF-1α) than adjacent normal renal tissue and normal cell HK-2. Vitro and vivo tests demonstrated that lentivirus-mediated CD74 knockdown inhibited the proliferation of ccRCC cell lines, induced G1/S arrest and apoptosis, and inhibited invasion. Inhibition of CD74 resulted in down-regulation of HIF-1α pathway proteins. CD74 was overexpressed in human ccRCCs and associated with tumor grade, and inhibition of CD74 produced ccRCC proliferation arrest, induced apoptosis, and inhibited invasion, which impinged on HIF-1α pathway-related proteins. It might represent a potential therapeutic target for ccRCC.

Ji SQ ，Su XL ，Cheng WL ，Zhang HJ ，Zhao YQ ，Han ZX ... -  《-》

miR-122 promotes metastasis of clear-cell renal cell carcinoma by downregulating Dicer.

Although overall downregulation of microRNAs (miRNAs) is a general feature of clear-cell renal cell carcinoma (ccRCC), several miRNAs are consistently upregulated, among which miR-122 was markedly increased in ccRCC tissues. Our study aims to determine the functional importance and underlying mechanism of miR-122 in ccRCC metastasis. Here, we demonstrate that the expression of miR-122 increased in ccRCC tissues, and higher miR-122 expression was found in ccRCC tissues with metastatic disease than in those without metastasis. The increased miR-122 levels were associated with poor metastasis-free survival in ccRCC patients with localized disease. Dicer was validated as a direct functional target of miR-122. Overexpression of miR-122 promoted migration and invasion of ccRCC cells in vitro and metastatic behavior of ccRCC cells in vivo. Inhibition of miR-122 attenuated this metastatic phenotype in vitro. Importantly, miR-122 exerted its pro-metastatic properties in ccRCC cells by downregulating Dicer and its downstream effector, the miR-200 family, thereby inducing epithelial-mesenchymal transition (EMT). Our results suggest an important role of the miR-122/Dicer/miR-200s/EMT pathway in ccRCC metastasis. Furthermore, miR-122 may serve as a biomarker for discriminating ccRCC with metastatic potential.

Fan Y ，Ma X ，Li H ，Gao Y ，Huang Q ，Zhang Y ，Bao X ，Du Q ，Luo G ，Liu K ，Meng Q ，Zhao C ，Zhang X ... -  《-》