Rituximab effectively reverses Tyrosine kinase inhibitors (TKIs) resistance through inhibiting the accumulation of rictor on mitochondria-associated ER-membrane (MAM)

Tyrosine kinase inhibitors (TKIs), a novel group of target-specific anti lung cancer drugs, have recently been found to resistant to some NSCLC cells which have the T790M EGFR mutation. However, recent investigations on the therapies of resistance to EGFR-TKIs are very limited. Therefore, it is important to develop more effective therapies to reverse EGFR-TKIs resistance. In our present study, erlotinib was used as the TKIs drug and the effects of the erlotinib on cell growth were evaluated. Cell viability and concentration dependent studies were performed using HCI-H1975 and HCI-H1299 cells alone with erlotinib, respectively. Further combined with rituximab, the results showed that erlotinib and rituximab were significantly inhibited the cell growth. Furthermore, the combination of erlotinib and rituximab greatly decreased the expression of p-mTOR and p-EGFR. Additional results from western blotting and immunofluorescence assays demonstrated that the accumulation of rictor was also decreased on MAM. Thus, all these results suggested that EGFR-TKIs combined with CD20 mono-antibody significantly decrease the cell growth of H1975 cells and H1299, with T790M EGFR mutation, and inhibit the localization of the key mTOR pathway proteins to MAM. So, it may be a promising strategy for overcoming EGFR TKI resistance in NSCLC patients.