Gastric cancer remains one of the major diseases plaguing people’s health in China as is evidenced by 400,000 affected people every year, accounting for 40% of world’s total number. The death rate in China is 4-8 times higher than developed countries. Although much work has been done to study the molecular mechanism underlying the progression of gastric cancer, it is still not sufficient.

Protease-activated receptors (PARs) are a unique family of G-protein coupled receptors. PAR4, the most recently identified PAR member, was reported to be overexpressed during the progression of colon and prostate cancers. Though PAR4 mRNA was detected in normal stomach, the role of PAR4 in gastric cancer has not been investigated. The research group headed by researcher ZHANG Yun from Kunming Institute of Zoology, Chinese Academy of Sciences (KIZ, CAS) made a study in this respect.

In the study, differential expression of PAR4 was measured by real-time PCR (n = 28) and tissue microarrays (n = 74). The results showed that PAR4 expression was remarkably decreased in gastric cancer tissues as compared with matched noncancerous tissues. And the frequently occurred down-regulation of PAR4 in gastric cancers was associated with more aggressive gastric cancer. Interestingly, the loss of PAR4 expression in gastric cancers may result from hypermethylation of the PAR4 promoter.

These results might provide valuable insights for understanding molecular mechanism of carcinogenesis, progression and metastasis of gastric cancers. The related paper has been published in International Journal of Biochemistry and Cell biology.

The work has received grants from National Basic Research Program of China (973 Program), National Natural Science Foundation of China, and CAS “Key Research Direction”.

The main findings have been published in International Journal of Biochemistry and Cell biology (http://www.sciencedirect.com/science/article/pii/S1357272511001427).