Loss of heterozygosity on chromosome 18 in microdissected gastric cancer cells

Genotype frequencies of the Val384Asp missense mutation in the hMLH1 gene in patients with familial gastric cancer

AIM: To investigate the etiological role of the missense mutation, Val384Asp, in the human mutL homolog 1 (hMLH1) gene in familial gastric cancer (FGC) based on a Chinese population in Jiangsu Province.

METHODS: A case-control study was conducted. One hundred newly diagnosed or suspected FGC patients and 180 healthy controls were included in the study. Peripheral white blood cells were obtained from all subjects for DNA extraction. The Val384Asp missense mutation was detected using PCR-based denaturing high-performance liquid chromatography (DHPLC) and verified by DNA sequencing. Bioinformatic software was then used to analyze the etiological mechanism of the Val384Asp missense mutation.

RESULTS: About 5% healthy individuals were Val384Asp carriers. Significant differences were noted for the following comparisons: patients with newly diagnosed or suspected FGC vs healthy controls (OR = 2.84, 95%CI: 1.07-7.81, P < 0.05), patients with an onset age ≥ 50 vs healthy controls (P < 0.05), patients with precancerous disease history vs healthy controls (P < 0.01), and patients having a high-risk family history of GC vs healthy controls (P < 0.05). Bioinformatic analysis showed that the Val384Asp missense mutation might destroy the structure of hMLH1 protein and impair its function. Besides, the conversion of T→A may disrupt pre-mRNA splicing.

CONCLUSION: The Val384Asp missense mutation may be associated with genetic susceptibility to FGC. Detection of the Val384Asp missense mutation may be able to help identify individuals with increased risk of FGC.

Loss of fragile histidine triad protein expression and its clinicopathological significance in gastric cancer

AIM: To investigate the expression of fragile histidine triad protein, Fhit and the possible relationship between its expression and clinicopathological indices in gastric carcinoma.

METHODS: Fhit protein expression was detected in 76 cases of gastric carcinoma, 58 dysplasia and 10 normal mucosae by immunohistochemical method to analyse its relationship to histological grade, clinical stage, metastatic status and prognosis.

RESULTS: The loss of Fhit protein expression was detected in 48/76 (63.2%) cases of cancer tissue, 36/58 (62.1%)cases of adjacent dysplastic tissue and 0/10 cases of normal gastric mucosa. There was a significant difference in the expression of Fhit protein between cancer or adjacent dysplastic tissue and normal gastric mucosa (P=0.000). It was also showed that loss of Fhit protein expression was found first in 35.7% (10/28) of grade I-II, and in 79.2% (38/48) of grade III (P = 0.000); second in 43.8% (14/32)of stage I-II, whereas in 77.3% (34/44) of stage III-IV (P = 0.004); and last in 36.4% (8/22) of tumors without metastasis but in 74.1% (40/54) of those with metastasis (P = 0.003). The significant difference in the loss of expression of Fhit was found between cancers on different histological grade, clinical stage and metastatic status, respectively. Follow-up data showed that there was a significant difference in median survival time between carcinomas with loss of Fhit (33 mos) and those without (71 mos) (Log rank = 20.78; P = 0.000).

CONCLUSION: Fhit protein is an important tumor suppressor protein. Loss of Fhit protein expression may be associated with carcinogenesis, invasion, metastasis and prognosis in gastric carcinoma.

Potassium antimonyl tartrate induces apoptosis in human gastric carcinoma cells

AIM: Potassium antimonyl tartrate (PAT), an antiparasitic agent, has rencently been shown to induce apoptosis of leukaemia cells. Its effects on human gastric cancer SGC-7901 cells and possible mechanism were investigated in this study.

METHODS: The growth inhibition of cells induced by various concentrations of PAT in different time course was analyzed by using MTT assay. The nuclei were stained by Hoechst 33 258 and the morphologic changes were observed by fluorescence microscope. TUNEL staining, double-staining, and flow cytomery were used to detect apoptosis of cells.

RESULTS: Growth inhibitory rates of SGC-7901 cells by PAT were significantly different in dose-and time-dependent manners (analysis of variance, P < 0.01). Chromatin condensation and nuclear fragmentation were seen under fluorescence microscope in the cells treated with Hoechst 33 258, and apoptotic cells were also detected by flow cytometry and TUNEL staining.

CONCLUSION: PAT can induce the apoptosis of SGC-7901 cells, and PAT may be a promising apoptosis-inducer in gastric cancer therapy.