In the present study, we underline the importance of combining c-Met Inhibitor (Inh.) and DSB repair Inhibitor (PARP Inh.) with the goal of accomplishing a synergistic therapeutic strategy in BRCA-mutated gastric carcinomas.
Firstly, to verify whether c-Met affects tumor response to PARP Inh., AGS (low c-Met expression) and Hs746T (high c-Met expression) cell lines, were subjected to knockdown c-Met expression, in the presence of PARP Inh. (NU1025). Subsequently, we examined the correlation between BRCA1/2 and c-Met. We knocked down BRCA1/2 expression in AGS and Hs746T cells and treated them with PARP Inh. Next, we examined the effects of combining c-Met Inh. (SU11274) and PARP Inh. (NU1025), measured by MTT, clonogenic cell survival and Annexin, assays. We also evaluated the effect of combining PARP Inh. and c-Met Inh. in AGS/Hs746T xenograft tumor models. AGS/Hs746T -pcDNA3 and AGS/Hs746T -siBRCA cells were injected into SCID mice. Tumor sizes were measured every 3 days. DNA damage was assessed by γ-H2AX staining.
Silence of Met expression promoted Hs746T cells more sensitive to PARP Inh. to similar levels as the AGS cells, as indicated by decreased cell viability. Silence of BRCA1/2 expression sensitized only AGS cells, signifying that increased expression of c-Met renders cells resistant to PARP Inh. in the context of inactivating BRCA1/2. Combining c-Met Inh. and PARP Inh. suppressed cell growth and clonogenicity and enhanced apoptosis in both AGS and Hs746T cells. The dual inhibition was demonstrated to be even more successful when cells were knockdown for BRCA1/2. Also, co-inhibition treatment substantially reduced tumor growth to AGS/Hs746T -pcDNA3 and more even effectively to AGS/Hs746T –siBRCA1/2 xenograft models, compared to either Inh. alone. DNA damage was higher in AGS/Hs746T –siBRCA1/2 compare to AGS/Hs746T -pcDNA3 xenograft models.
BRCA deficiency renders gastric tumor cells sensitive to PARP inhibition. In addition, treatment with c-Met Inh. enhanced Hs746T sensitivity to the PARP Inh. Our data demonstrate that dual Met/PARP inhibition is synergistic providing an effective therapeutic strategy in BRCA-mutated gastric carcinomas.
Clinical trial identification
Legal entity responsible for the study
All authors have declared no conflicts of interest.