RESUMO
<p><b>OBJECTIVE</b>To explore the mutation and amplification of RIT1 gene and their correlation with carcinogenesis of hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>The polymerase chain reactioindirect sequencing method was used for detecting the mutations in the sequence of all 6 exons in the RIT1 gene of 50 HCC tissues and paratumor tissues. And the amplification of RIT1 gene was examined by fluorescence quantitative polymerase chain reaction method.</p><p><b>RESULTS</b>A nucleotide 241 G --> C substitution in exon 5 of RIT1 gene was detected in one patient's HCC tissue, but not in paratumor tissue; this 241 G --> C substitution leads to Glu81Gln amino acid alteration in the conservative domain binding GTP. A nucleotide G --> C substitution in 5'-UTR (-21 bp from initial codon) was detected in all of the 50 HCC tissues and paratumor tissues, and 2- to 297-fold amplification of RIT1 gene was detected in 11 of 43 qualified cases, the amplification frequency being 25.6%.</p><p><b>CONCLUSION</b>Gene amplification is one of the main activating ways of RIT1 gene in HCC, and its amplification might be correlated with HCC carcinogenesis, while point mutation might be not.</p>