Promoter polymorphism of MRP1 associated with reduced survival in hepatocellular carcinoma.

AIM: to investigate the effect of the G-1666A polymorphism in the multidrug resistance related protein-1 (MRP1) on outcome of hepatocellular carcinoma (HCC). METHODS: a cohort of 162 patients with surgically resected HCC who received no postsurgical treatment until relapse was studied. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism analysis. Electrophoretic mobility shift assay (EMSA) was used to evaluate the influence of the G-1666A polymorphism on the binding affinity of the MRP1 promoter with its putative transcription factors. RESULTS: Kaplan-Meier analysis showed that patients with GG homologues had a reduced 4-year disease-free survival compared with those carrying at least one A allele (P = 0.011). Multivariate Cox regression analysis indicated that the -1666GG genotype represented an independent predictor of poorer disease-free survival [hazard ratio (HR) = 3.067, 95% confidence interval (CI): 1.587-5.952, P = 0.001], and this trend became worse in men (HR = 3.154, 95% CI: 1.604-6.201, P = 0.001). A similar association was also observed between 4-year overall survival and the polymorphism in men (HR = 3.342, 95% CI: 1.474-7.576, P = 0.004). Moreover, EMSA suggested that the G allele had a stronger binding affinity to nuclear proteins. CONCLUSION: the MRP1 -1666GG genotype predicted a worse outcome and was an independent predictor of poor survival in patients with HCC from Southeast China.

Characterization of the Sesbania rostrata phytochelatin synthase gene: alternative splicing and function of four isoforms.

Phytochelatins (PCs) play an important role in detoxification of heavy metals in plants. PCs are synthesized from glutathione by phytochelatin synthase (PCS), a dipeptidyltransferase. Sesbania rostrata is a tropical legume plant that can tolerate high concentrations of Cd and Zn. In this study, the S. rostrata PCS gene (SrPCS) and cDNAs were isolated and characterized. Southern blot and sequence analysis revealed that a single copy of the SrPCS gene occurs in the S. rostrata genome, and produces four different SrPCS mRNAs and proteins, SrPCS1-SrPCS4, by alternative splicing of the SrPCS pre-mRNA. The SrPCS1 and SrPCS3 proteins conferred Cd tolerance when expressed in yeast cells, whereas the SrPCS2 and SrPCS4 proteins, which lack the catalytic triad and the N-terminal domains, did not. These results suggested that SrPCS1 and SrPCS3 have potential applications in genetic engineering of plants for enhancing heavy metal tolerance and phytoremediation of contaminated soils.