Synergistic cytotoxicity of recombinant IGFBP-3 and cisplatin in HPV18-positive HeLa cells via NF-κB inflammatory modulation.

Abstract

Background and purpose: Insulin-like growth factor-binding protein-3 (IGFBP-3), a tumor suppressor and inhibitor of nuclear factor kappa B (NF-kB), has emerged as a promising candidate for therapeutic application across diverse pathological conditions. Given NF-kB's role in cervical cancer development and cisplatin resistance, this study examines the effects of recombinant human IGFBP-3 (rhIGFBP-3), alone and in combination with cisplatin, on NF-kB levels, inflammatory modulation, and apoptotic response in HeLa cells, and investigates whether rhIGFBP-3 can reduce the cisplatin dose.

Experimental approach: The impact of rhIGFBP-3, alone and in combination with cisplatin, on HeLa cells' viability was evaluated by assessing cell viability (MTT assay); apoptosis (cell cycle analysis, TUNEL, annexin V/PI staining, Bax/Bcl-2 ratio, caspase activity); and NF-kB p65 levels (western blot). Gene expression of inflammatory cytokines and enzymes (IL-6, IL-8, COX-2, iNOS) was analyzed by RT-PCR.

Findings/results: Cisplatin and rhIGFBP-3 inhibited HeLa cell growth in a concentration-dependent manner (IC₅₀ = 6.06 μg/mL and 1.12 μg/mL, respectively). Their combination exhibited synergistic cytotoxicity (combination index < 1), allowing ~2.1-fold reductions in concentration to 2.53 μg/mL cisplatin and 0.46 μg/mL rhIGFBP-3 for 45% growth inhibition. Compared to monotherapy, the combination significantly enhanced apoptosis and DNA fragmentation, sub-G1 accumulation, caspase-8/9/3/7 activation, and BAX/BCL-2 ratio. It also considerably reduced NF-kB p65 and inflammatory markers in comparison with cisplatin alone.

Conclusion and implications: Our study demonstrated that rhIGFBP-3 enhanced cisplatin efficacy by promoting apoptosis and attenuating inflammation, highlighting its potential as both a cisplatin adjuvant and a monotherapy in HeLa cells.