[LASS2/TMSG1 gene silencing promotes the invasiveness and metastatic of human prostatic carcinoma cells through increase in vacuolar ATPase activity]

Abstract

Objective: To explore the effects of LASS2/TMSG1 silencing on the growth, invasion and metastasis of prostate carcinoma cells and to investigate the related molecular mechanisms.

Methods: LASS2/TMSG1 expression of human prostate carcinoma cell line with low metastatic potentiality (PC-3M-2B4 cells) was knocked down using DNA vector-based small interfering RNA (shRNA), followed by evaluations of tumor cell invasion and metastasis.

Results: A stable PC-3M-2B4 cell line with expression of LASS2/TMSG1-shRNA was successfully established. MTT assay showed PC-3M-2B4 cells exhibited a strong proliferation after transfection of LASS2/TMSG1-shRNA.LASS2/TMSG1-shRNA transfected clones demonstrated an increased clonogenicity by soft agar colony formation assay and a significant increase of tumor cell invasion by matrigel invasion study.Flow cytometry showed that after LASS2/TMSG1 gene silencing, the apoptotic rate of PC-3M-2B4 cell significantly decreased (P<0.01) without significant cell cycle change (P>0.05).Eight weeks after implantation into subcutaneous tissues in BAL B/c (nu+) mice, the size and weight of sh-LASS2/TMSG1 xenografts were significantly larger than those of the control group (P<0.05).Nuclear proliferation index of the subcutaneous tumor was also higher in the LASS2/TMSG1 shRNA group than those in the control group. Lymph node metastasis was observed in 5 of 6 mice of LASS2/TMSG1 shRNA group and only 1 of 6 of the control group. V-ATPase activity, activities of secreted MMP-2 and MMP-9 and extracellular hydrogen ion concentration were significantly increased in LASS2/TMSG1-shRNA group compared with the control group (P<0.05).

Conclusion: Silencing of LASS2/TMSG1 promotes the growth, invasion and metastasis of prostate cancer cells through up-regulation of V-ATPase activity, indicating that LASS2/TMSG1 is a tumor metastasis suppressor gene.