The basal body gene, RPGRIP1L, is a candidate tumour suppressor gene in human hepatocellular carcinoma.
Loss of heterozygosity (LOH) on chromosome 16q is one of the most frequent genetic alterations in hepatocellular carcinoma (HCC). Our previous data showed that the smallest common deleted region was between D16S415 and D16S419, encompassed approximately by a 0.75cM region on 16q12.2, suggesting that the putative tumour suppressor genes (TSGs) at this locus might be involved in the development of HCC. Of the four genes (CHD9, RBL2, AKTIP and RPGRIP1L) located in this region, only RPGRIP1L was downregulated in HCCs. Downregulation of RPGRIP1L was found in 91% (10/11) HCC cell lines and in 35% (14/40) HCCs, respectively. To investigate the role of RPGRIP1L in HCCs, we used the overexpression of RPGRIP1L in four HCC cell lines (HepG2, Huh6, Huh7 and Hep3B). Overexpression of RPGRIP1L suppressed colony formation of tumour cells. Conversely, expression of RPGRIP1LM (dominant negative form) in HCC cells enhanced colony formation. Furthermore, knockdown RPGRIP1L by RNA interference in SK-HepI cells promoted colony formation. Taken together, these data strongly suggest that RPGRIP1L might be the putative TSG in HCC. Moreover, we showed that Mad2, Survivin and Securin were elevated in RPGRIP1LM-HepG2 transfectants and RPGRIP1L-shRNA-SK-HepI transfectants. After knockdown of MAD2 in RPGRIP1L-shRNA-SK-HepI transfectants partly reverse cellular colony formation capability. These data suggest that RPGRIP1L suppresses anchorage-independent growth partly through the mitotic checkpoint protein Mad2.
Lin
Ya-Wen
YW
Department of Microbiology and Immunology, National Defense Medical Center, Taipei 114, Taiwan. ndmc.yawen@msa.hinet.net
Yan
Ming-De
MD
Shih
Yu-Lueng
YL
Hsieh
Chung-Bao
CB
D048868:Adaptor Proteins, Signal Transducing / Q000032:analysis / Q000235:genetics*; D000595:Amino Acid Sequence; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000737:chemistry / Q000235:genetics* / Q000821:virology; D018797:Cell Cycle Proteins / Q000235:genetics; D045744:Cell Line, Tumor; D002885:Chromosomes, Human, Pair 16; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D020868:Gene Silencing; D016147:Genes, Tumor Suppressor; D006509:Hepatitis B / Q000150:complications; D006515:Hepatitis B virus; D006801:Humans; D008113:Liver Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000821:virology; D019656:Loss of Heterozygosity; D064246:Mad2 Proteins; D008969:Molecular Sequence Data; D034622:RNA Interference; D012097:Repressor Proteins / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; C577697:MAD2L1 protein, human; D064246:Mad2 Proteins; C532826:RPGRIP1L protein, human; D012097:Repressor Proteins