Overexpression of hMSH2 and hMLH1 protein in certain gastric cancers and their surrounding mucosae

Mismatch repair (MMR) deficiency is closely related to oncogenesis, which is usually accompanied with the loss of expression of hMSH2 and/or hMLH1. These two proteins are detected in many gastric cancers (GCs), and even their overexpression have been reported in certain other cancers. We studied the protein expression levels of MMR (hMSH2 and hMLH1), PCNA and Ki67 in the cancers and surrounding mucosae (SMs) collected from the patients with GC and gastric mucosa samples from non-cancer patients (NCMs), using immunohistochemistry. Our results demonstrated that the positive MMR protein expression levels were 69.1% (132/191), 33.1% (44/133) and 7.1% (3/42) in GCs, SMs and NCMs, respectively (P<0.001); the positive PCNA protein expression levels were 92.1% (176/191), 75.9% (101/133) and 23.8% (10/42), respectively (P<0.001); the positive Ki67 protein expression levels were 79.1% (68/86), 29.2% (21/72) and 45.2% (19/42), respectively (P