Poster Presentation 35th Lorne Cancer Conference 2023

Kisspeptin pretreatment promotes Temozolomide-induced apoptosis by inhibiting cyto-protective autophagy in KISS1R-expressing glioblastoma cells (#316)

Isra IS Saif eldin Eisa Sati 1 , Rakesh Naidu RN Naidu 1 , Tomoko TS Soga 1 , Muhamad Noor Alfarizal MNA Bin Kamarudin 1
  1. Monash University, Subang Jaya, SELANGOR, Malaysia

Targeting G-couple protein receptors have shown some successful outcomes against various cancers.  The activation of the KISS1-receptor (KISS1R), also known as GPR54, by kisspeptin has shown to modulate cancer response to chemotherapeutic drugs. The preliminary data shows the pretreatment with KP-10 (100 nM) for one hour prior to TMZ addition further reduced TMZ IC50 in comparison to TMZ treated group at 24 and 48 hours (***p<0.001). This study aims to investigate the cell death mechanisms and signalling pathways involved in the combination treatment of  KP-10 and TMZ in KISS1R-expressing GBM.  MTT cell viability assay and isobologram analysis were used to determine the synergistic effect of KP-10/TMZ treatment, while cytometric assessment of cell cycle, Annexin V and autophagy were used to identify the activated mechanism of cell death. The isobologram analysis of  KP-10 ( 100 nM) combination with TMZ of 31.25, 62.5 and 125 μM resulted in a combination index values between 0.57-0.19 demonstrating a strong level of synergism and drug reduction index of TMZ up to five time the effective dose when compared to TMZ-only treated sample. Pathway analysis using WikiPathways, KEGG and STITCH predicted the interaction between KP-10 and TMZ at key caliber pathways of apoptosis, cyto-protective autophagy and ferroptosis. Cytometric annexin V evaluation confirmed the synergistic apoptotic induction where the synergistic combinations increased early, late and total apoptotic cell population when compared to TMZ single treatment.  The double staining with hoechst 33342 and propidium iodide showed signs of apoptosis initiation as early as 12 hours in all  KP-10/TMZ synergistic combination while a  significant decrease of  autophagy marker LC-3  was observed, indicating an inhibition of autophagy leading to  induction of apoptosis. These results were reversed when recovery assay using autophagy pharmacological inducer rapamycin was used. Collectively, these results demonstrate that KP-10 synergises TMZ activity through reduction of protective autophagy leading to apoptosis acceleration in favor of TMZ. Moving forward, this study will focus on understanding the main signalling pathways involved through using LCMS/MS and JESS simple western.