MYC pathway is activated in clear cell renal cell carcinoma and essential for proliferation of clear cell renal cell carcinoma cells.

Clear cell renal cell carcinoma (ccRCC) is the major and aggressive subtype of RCC. Previously, we identified 383 differentially expressed genes by analyzing full-length cDNA libraries of ccRCC and normal kidney tissues. In this study, we applied functional network analysis to the differentially expressed genes for identifying deregulated molecular pathways in ccRCC, and the results indicated that MYC showed a prominent role in the highest scoring network. The upregulation of MYC expression was validated in ccRCC tissues and cell lines. Furthermore, Knockdown of MYC expression by MYC-specific siRNA significantly inhibited the abilities of uncontrolled proliferation, anchorage-independent growth and arrested cell cycle in the G0/G1 phase in ccRCC cells. Moreover, we found that 37 differentially expressed genes were shown to be MYC-target genes, and the upregulation of the MYC-target genes BCL2, CCND1, PCNA, PGK1, and VEGFA were demonstrated. The expression of these MYC-target genes was significantly correlated with the expression of MYC in ccRCC tissues, and knockdown of MYC also suppressed the expression of these MYC-target genes in ccRCC cells. The recruitment of MYC to the promoter regions of BCL2, CCND1, PCNA, PGK1, and VEGFA was shown by Chromatin immunoprecipitation assay. These results suggest that MYC pathway is activated and plays an essential role in the proliferation of ccRCC cells.

Gene expression analysis of human hepatocellular carcinoma by using full-length cDNA library.

Hepatocellular carcinoma (HCC) is a leading cause of death worldwide. Hepatitis B virus (HBV) or hepatitis C virus (HCV) infection has been shown to cause hepatic carcinogenesis. A total 58,251 of cDNA clones of full-length cDNA libraries of HBV and HCV-infected HCC and their surrounding non-tumor tissues, respectively, were sequenced and analyzed by blasting against GENEBANK maintained by NCBI. About 180 and 279 of genes were shown an obviously increased and decreased expression patterns between HCC tissue and its adjacent non-tumor tissue. The candidate genes consisted of the genes encoded liver specific metabolism enzymes, secretory functional proteins, proteases and their inhibitors, protein chaperon, cell cycle components, apoptosis-related proteins, transcriptional factors, and DNA binding proteins. Several genes were further investigated by using real-time PCR to confirm the gene expression levels in at least 24 pairs of HCC tissues and adjacent non-tumor tissues. The results showed that genes encoded reticulon 4, RGS-1, antiplasmin, and kallikrein B were down-regulated with the average of 2.8, 8.5, 3.2, and 10.5-fold, respectively. Our results provide crucial candidate genes to develop clinical diagnosis and gene therapy of HCC.

Identification of differentially expressed genes in clear cell renal cell carcinoma by analysis of full-length enriched cDNA library.

Renal cell carcinoma (RCC) is the most common malignancy in adult kidney, and accounts for 3% of malignancies worldwide with increasing incidence. Clear cell RCC (ccRCC) is the major type in RCC. Resection by surgery is the main treatment because the response of ccRCC to traditional therapies is very poor. To identify the tumor-associated genes for better understanding the molecular mechanism of ccRCC, the full-length enriched cDNA libraries of ccRCC and normal kidney tissues were constructed by the oligo-capping method. Nucleotide sequences of the cDNA libraries of ccRCC and normal kidney tissues were sequenced. From the sequence analysis of 19,425 and 12,400 clones of ccRCC and normal kidney tissues, 4356 and 3055 genes were identified, respectively. By comparing the gene-expression patterns of ccRCC and normal tissues, the up- or down-regulated genes were identified. Among these identified genes, the differential expression of annexin A2 and argininosuccinate synthetase genes were further confirmed by quantitative real-time PCR and Western blot analysis.