Trastuzumab regulates phosphoinositide 3 kinase/protein kinase B/mammalian target of rapamycin pathway to improve chemotherapy resistance in lymphoma cells

Abstract

This study assessed the effect of trastuzumab on PI3K/AKT/mTOR (phosphatidylinositol-3-kinase/Protein Kinase B/Mechanistic Target of Rapamycin) pathway and chemotherapy resistance of lymphoma cells. The expressions of p-AKT (Rat phosphorylated AKT protein) and p-mTOR (Mouse p-mammalian target of rapamyein) were measured by immunohistochemical analysis, immunoblotting, real-time qPCR (quantitative polymerase chain reaction) and Western blot, along with analysis of drug resistance rate, cell viability, anti-tumor activity and apoptosis. p-AKT (Rat phosphorylated AKT protein) and p-mTOR (Mouse p-mammalian target of rapamyein) were abundantly expressed in the cytoplasm, while p-S6 was only abundantly present near the nucleus, and p-4E-BP1 was abundantly expressed at both sites. All the proteins were highly expressed in PCNSL (primary central nervoussy stemlymphoma) except for p-AKT (P < 0.05). In addition, the proliferation rate of drug-resistant cells was rapid in the presence of drugs. The p-AKT level of trastuzumab chemo resistant Raji cells was significantly lower than Raji 2R and Raji 4RH cell lines. Moreover, Trastuzumab sensitivity was significantly increased in cells after inhibitory expression and overexpression of PIK3R2. MK-2206 inhibited Akt and decreased cell proliferation. p-AKT knockdown decreased Raji cell activity after exposure to doxorubicin. MK2206 and doxorubicin jointly promoted PARP (poly ADP-ribose polymerase) cleavage, and cells were exposed to MK2206 and either adriamycin or dexamethasone, both had a synergistic effect on reducing cell viability. Idelalisib exposure resulted in altered expression of Bcl-2. p-AKT and p-mTOR were significantly elevated in PCNSL specimens, along with higher expressions of p-S6 and p-4E-BP1. Drug-resistant cells proliferated faster than parental sensitive cells in the presence of drugs, and Raji cells sensitive to trastuzumab chemotherapy had low p-AKT expression. Finally, MK-2206 inhibited Akt and reduced viability of BL cell lines. p-AKT inhibition resulted in enhanced response to cytotoxic chemotherapy and promotes apoptosis after cytotoxic chemotherapy.