Significances of contactin-1 expression in human gastric cancer and knockdown of contactin-1 expression inhibits invasion and metastasis of MKN45 gastric cancer cells.

Contactin-1 (CNTN-1) has been shown to promote cancer metastasis. Previously, we have reported that the expression of CNTN-1 was upregulated in gastric cancer tissues compared with adjacent normal tissues. Here, we investigated the significance of CNTN-1 expression and its underlying mechanism of metastasis mediated by epithelial-mesenchymal transition (EMT) in gastric cancer. The expressions of CNTN-1 and EMT-related proteins were assayed through immunohistochemical staining of pathological specimens from patients with gastric cancer. Other methods including reverse transcriptase polymerase chain reaction, Western blotting, stably transfected against CNTN-1 into MKN45 cells, migration and invasion assays in vitro and nude mouse tumorigenicity in vivo were also utilized. The results revealed that CNTN-1 expression was elevated and positively correlated with metastasis, EMT-related markers and poor prognosis in patients with gastric cancer. Moreover, CNTN-1 expression might associate with invasive ability to some extent in gastric cancer cell lines KATO-Ш, SGC7901 and MKN45. Knockdown of CNTN-1 expression in MKN45 cells using short hairpin RNA (shRNA) had notable effects on cell migration and invasion, rather than proliferation in vitro and in vivo. Furthermore, suppression of CNTN-1 expression altered EMT through inhibition of transcription factor Slug, rather than Snail. Our study demonstrated that the elevated CNTN-1 expression closely correlated with cancer metastasis and patient survival, and its functions seemed to be important in migration and invasion of gastric cancer cells via EMT alteration probably mediated by inhibition of Slug. CNTN-1 may be a potential therapeutic target for gastric cancer.