| Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Globally, there are approximately 600,000 new cases of liver cancer reported per year, ranking the fifth among all malignancies. Occupying more than half of all the HCC cases, Hepatocellular carcinoma in China has become a big threat to the health of the people in our country. Because clinical diagnosis is often difficult, especially early in the course of the disease, most detected patients are already too late to experience ablation, which is the most effective. For patients with late-stage and advanced metastatic HCC, chemotherapy is the first and best option. The development of HCC is accompanied by changes of oncogenes and tumor suppressor genes. p53, a tumor suppressor gene, which is the most likely to mutate during human cancers, has mutated in more than half of tumors.By detecting the sequences of p53 genes in the Qi Dong samples, we found 49% of cases had mutant p53, among which, R249S mutant occupied 33.9%. Besides, the age of patients and prognosis were closely associated with the mutation of p53. Many studies have showed that the state of p53 is a potential biomarker for the diagnosis of HCC. Because of the high frequency of R249S mutation of p53 in the Qi Dong HCC patients, we used Sequence Specific Blocking PCR (ASB-Realtime PCR) to detect the cDNA of blood plasma of 569 patients to screen p53 mutations. The results showed that R249S mutant of p53 occupied 53% and this mutation was negatively correlated with prognosis. Through the method mentioned above, we could detect the genotypes of HCC patients and infer the prognosis.To apply the method in treatment, and achieve personalized diagnosis, we selected 8 major mutations (R110L, V157F, A159P, Y220C, R248L, R249S,294 delete (Frame shift) and R342X) among the HCC samples mentioned above, and studied the effects they had on the proliferation and migration of hepatoma cells and the tolerance to clinically common drugs, like DOX, Taxol and VCR of hepatoma cells. Our results showed that most mutated p53 could significantly improve the proliferation and migration of hepatoma cells. The effects of Y220C and R249S mutations of p53 were strongest.In the following drug-screening experiments, we found most mutant could increase the tolerance of hepatoma cells to the three drugs mentioned above, while WT-p53 could increase the sensitivity of hepatoma cells to the drugs.We further detected cell cycle and apoptosis through Flow Cytometer, and found that after the treatment of DOX, mutant p53(R249S,294delete, R110L, V157F, R342X) could increase cell viability by decelebrating the transition of hepatoma cells from stage G1 to stage G2/M, which retarded apoptosis caused by the blocking of stage G2/M. After the treatment of Taxol, mutant p53(R249S, V157F, R342X,R110L) could decrease the inhibition of Taxol to the proliferation of cells by decelebrating the procedure from G2/M blocking to apoptosis induced by Taxol. While after the treatment of VCR, mutant p53(R110L,V157F, R248L, R249S)could also inhibit the apoptosis caused by G2/M blocking. At last, we investigated the mechanisms underlying the above phenomenon. The results showed that mutant p53 could not effectively activate Bax pathway, which could be effectively activated by WT-p53, when compared with control groups.In conclusion, our study found 8 high frequency p53 mutations in Qi Dong District, China, and discovered that these mutations could significantly increase the proliferation of hepatoma cells and found out a major reason why hepatoma cells could gain resistance to DOX, Taxol and VCR. Our results also explained the negative correlation between p53 mutation and the treatment and prognosis of patients, found a breakthrough for drug therapies and provided evidence for doctors to choose different drugs for different patients with different mutations.
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