Mycoplasma hyorhinis infection in gastric carcinoma and its effects on the malignant phenotypes of gastric cancer cells

BACKGROUND Mycoplasma hyorhinis infection has been postulated to play a role in the development of several types of cancer, but the direct evidence and mechanism remained to be determined. METHODS Immunohistochemistry assay and nested polymerase-chain reaction (PCR) were performed to examine the mycoplasma hyorhinis infection in gastric cancer tissues. Statistical analysis was used to check the association between mycoplasma infection and clinicopathologic parameters. Transwell chamber assay and metastasis assay were used to evaluate mycoplasma hyorhinis' effects on metastasis in vitro and in vivo. Mycoplasma hyorhinis-induced extracellular signal-regulated kinase (ERK) and epidermal growth factor receptor (EGFR) activation were investigated by Western blot. RESULTS Mycoplasma hyorhinis infection in gastric cancer tissues was revealed and statistical analysis indicated a significant association between mycoplasma infections and lymph node metastasis, Lauren's Classification, TNM stage, and age of the patients. Mycoplasma hyorhinis promoted tumor cell migration, invasion and metastasis in vitro and in vivo, which was possibly associated with the enhanced phosphorylation of EGFR and ERK1/2. The antibody against p37 protein of Mycoplasma hyorhinis could inhibit the migration of the infected cells. CONCLUSIONS The infection of mycoplasma hyorhinis may contribute to the development of gastric cancer and Mycoplasma hyorhinis-induced malignant phenotypes were possibly mediated by p37.