Abstract:

Objective   To evaluate whether over-expressed inositol poly-phosphate 4-phosphatase type II (INPP4B) had a direct effect to suppress MDA-MB-231 cell proliferation. Methods   Reverse transcription PCR and Western blotting were performed to confirm the expression of INPP4B in triple-negative breast cancer cell line MDA-MB-231, which was then transferred with a retrovirus-mediated expression system carrying INPP4B gene. After that, real-time PCR was adopted to measure INPP4B mRNA. Phosphorylated serine-threonine protein kinase B/AKT (p-AKT) and INPP4B protein levels in MDA-MB-231 cells infected with lentivirus were assessed with Western blotting. Cell viability, apoptosis and cycle distribution were evaluated with CCK-8 assay and flow cytometry. Results   Decreased expression of INPP4B was observed in MDA-MB-231 cells. The expressions of INPP4B in mRNA and protein levels were elevated via lentiviral transfection, demonstrating that over-expression of INPP4B by lentiviral vector down-regulated the levels of p-AKT, suppressed the cell proliferation and resulted in an accumulation of G0/G1 phase. Conclusion    Over-expression of INPP4B in MDA-MB-231 cells shows a remarkable drop in growth rate associated with down-regulated PI3K/AKT signaling pathway by reducing AKT phosphorylation, which may bear potential therapeutic significance for patients with TNBC.

Key words: Lentivirus; INPP4B gene; Triple-negative breast cancer; Proliferation; Phosphorylated serine-threonine protein kinase B