Glutathione S-transferase mu2 suppresses cancer cell metastasis in non-small cell lung cancer.

Glutathione S-transferase mu2 (GST-M2) is a phase II detoxification enzyme. Low expression of GST-M2 in lung cancers is due to hypermethylation of its promoter. Lung cancer with the GST mu-null genotype is associated with shorter survival. However, a correlation between GST-M2 and important clinical parameters, as well as the migration of GST-M2-defective cells in lung cancer, has not been established. In the present study, we investigate the role of GST-M2 in cell migration and actin disassembly in lung cancer cells. GST-M2 and CCN2 mRNA levels were significantly reduced in non-small cell lung cancer (NSCLC) tumors when compared with matched normal lung tissues in 82 patients with NSCLC. We found that high expressions of both GST-M2 and CCN2 are correlated with favorable survival of patients with lung cancer when compared with similar patients without GST-M2 or CCN2 expression. GST-M2 can induce CCN2 expression by driving the CCN2 proximal promoter. Overexpression of GST-M2 decreases the formation of filopodia, resulting in remodeling of the reorganized cytoskeletons. Overexpression of GST-M2 significantly suppressed cancer cell migration on wound-healing assay. In addition, overexpression of GST-M2 dramatically reduced tumor growth and metastasis in a xenograft mouse model. These data highlight the potential of GST-M2 as a novel tumor suppressor. GST-M2 increases the expression of CCN2 in lung cancer cells, which inhibits cancer cell migration in lung cancer and animal models.