Yuanying Zhang

Germline mutations and polymorphic variants in MMR, E-cadherin and MYH genes associated with familial gastric cancer in Jiangsu of China

Germline mutations in MSH2, MLH1, E‐cadherin and MutY (MYH) genes have been implicated in the occurrence of gastric cancer (GC). Epidemiological investigation was performed by recruiting patients with GC onset during 2002 in Jiangsu province, China. We identified suspected hereditary GC patients based on either the GC family history or GC onset at early ages. We have screened germline variations in 101 suspected hereditary GC patients at the coding sequences of MSH2, MLH1, E‐cadherin and MYH genes with polymerase chain reaction‐denaturing high‐performance liquid chromatography (PCR‐DHPLC) analysis and DNA sequencing. The result showed that about 40% of patients carried germline variations, predominantly with missense mutations. Of the variations detected are 2 base pair substitutions, c.53C > T and c.74G > A, which is predicted to generate missense mutations of p.Pro18Leu and p.Gly25Asp, respectively, and occurred at the same allele of MYH gene. The frequency of variant haplotype T/A in patients was higher than that in the control group (p = 0.021, odds ratio [OR] = 4.43, 95% confidence interval [95% CI] = 1.33–14.72). Difference in the frequency of the silent mutation p.Asn751Asn in E‐cadherin gene was also found between patients and controls (p = 0.009, OR = 2.54, 95% CI = 1.30–4.95). Moreover, 6 types of variations were detected in MSH2 and MLH1 genes in 14 of 101 patients. Most of them occurred at exon7 of MSH2, frequently c.1168C > T, resulting in mutation of p.Leu390Phe. In summary, germline mutation at MSH2, MLH1, E‐cadherin and MYH genes is a frequent event in the familial GC. They may form a genetic basis for the familial GC susceptibility in Chinese population.

Plasma Post-operative miR-21 Expression in the Prognosis of Gastric Cancers

Tumor-associated microRNAs have been detected in serum or plasma, but whether plasma microRNA-21 (miR-21) could be a potential circulating biomarker for gastric cancer (GC) prognosis in Chinese is still uncertain. Real-time quantitative reverse transcription PCR (qRT-PCR) was employed in this study to compare the relative expression of miR-21 between pre-operative and post-operative paired plasmas from 42 patients with primary GCs. The results showed that the expression levels of miR-21 in the post-operative plasmas were significantly reduced by an average of 18.2 times in all patients when compared to the pre-operative plasmas, and by 22.1 times in the subgroup of patients without family history, while only 1.76 times in the subgroup of patients with a family history. With respect of clinicopathological characteristics, the plasma miR-21 expression was highly associated with differentiation degree and lymph node metastasis rate. The results suggested plasma miR-21 could be a novel potential biomarker for GC prognosis and evaluation of surgery outcomes, especially in patients without a family history.

Curcumin inhibits aerobic glycolysis and induces mitochondrial-mediated apoptosis through hexokinase II in human colorectal cancer cells in vitro.

Curcumin, the major pigment of the dietary spice turmeric, has the potential for chemoprevention by promotion of apoptosis. Here, we investigated the molecular mechanisms of curcumin in glycolytic inhibition and apoptotic induction in human colorectal cancer HCT116 and HT29 cells. On the one hand, curcumin downregulated the expression and activity of hexokinase II (HKII) in HCT116 and HT29 cells in a concentration-dependent manner, but had little effect on the other key glycolytic enzymes (PFK, PGM, and LDH). On the other, curcumin induced dissociation of HKII from the mitochondria, resulting in mitochondrial-mediated apoptosis. Furthermore, the phosphorylation of mitochondrial HKII through AKT was responsible for the curcumin-induced dissociation of HKII, which was different from the mechanism of HKII inhibitor 3-BrPA. These results have important implications for the metabolism reprogramming effect and the susceptibility to curcumin-induced mitochondrial cytotoxicity through the regulation of HKII, and provide a molecular basis for the development of naturally compounds as novel anticancer agents for colorectal carcinoma.

Analysis of human MutS homolog 2 missense mutations in patients with colorectal cancer

Germline mutations of DNA mismatch repair gene human MutS homolog 2 (hMSH2) are associated with hereditary nonpolyposis colorectal cancer (HNPCC). A total of one-third of these mutations are missense mutations. Several hMSH2 missense mutations have been identified in patients in East Asia, although their function has not been evaluated. In the present study, the role of ten hMSH2 missense mutations in the pathogenesis of colorectal cancer was examined. The hMSH2/hMSH6 protein interaction system was established using yeast two-hybrid screening. Next, the missense mutations were analyzed for their ability to affect the protein interaction of hMSH2 with its partner hMSH6. Additionally, the Sorting Intolerant from Tolerant tool was applied to predict the effects of different amino acid substitutions. The results demonstrated that certain hMSH2 mutations (L173R and C199R) caused a significant functional change in the human hMutSα complex and were identified to be pathological mutations. The Y408C, D603Y, P696L and S703Y mutations partially affected interaction and partly affected the function of hMSH2. The remaining four variants, T8M, I169V, A370T and Q419K, may be non-functional polymorphisms or could affect protein function through other molecular mechanisms. The present study evaluated the functional consequences of previously unknown missense mutations in hMSH2, and may contribute to improved clinical diagnosis and mutation screening of HNPCC.