[Molecular mechanism of reversing metastatic phenotype in human high-metastatic large cell lung cancer cell line L9981 by nm23-H1]

Abstract

Background & objective: nm23-H1, a tumor metastasis suppressive gene, can reverse tumor metastasis phenotype. But the molecular mechanism of nm23-H1 in inhibiting or reversing metastasis of lung cancer is unclear. This study was to explore the molecular mechanism of nm23-H1 in reversing metastasis phenotype of lung cancer.

Methods: nm23-H1 gene and pLXSN were separately transfected into human lung cancer cell line L9981. Proliferation of L9981, L9981-pLXSN, and L9981-nm23-H1 cells was detected by MTT assay, cell invasive ability was detected by modified Boyden chamber. Tumorigenesis and experimental lung metastasis were determined in vivo. mRNA and protein levels of beta-catenin, E-Cadherin, CD44S, CD44V6, matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase-1 (TIMP-1), and vascular endothelial growth factor (VEGF) were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot.

Results: (1)Cell proliferation, clone formation, and invasive ability were significantly lower in L9981-nm23-H1 cells than in L9981 cells [(19.5+/-2.9)% vs. 100%, 10.3+/-0.7 vs. 21.7+/-1.3, 31.0+/-3.0 vs. 151.0+/-6.3, P<0.01]. (2) The inhibitory rate of tumorigenesis of nude mice was significantly higher in L8891-nm23-H1 group than in L9981 group (85.6% vs. 0%, P<0.001)u the lung metastatic rate was significantly lower in L9981-nm23-H1 group than in L9981 group (0% vs. 100%, P<0.001). (3)nm23-H1 up-regulated mRNA and protein levels of beta-catenin, E-Cadherin, and TIMP-1, and down-regulated levels of MMP-2, CD44V6, and VEGF (P<0.01). (4) nm23-H1 up-regulated mRNA level of CD44s, protein level of CD44s didn't change (P>0.05).

Conclusion: nm23-H1 gene can reverse malignant and metastatic phenotype of L9981 cells through regulating the expressions of lung cancer metastasis-related genes.