Managing cervical cancer using multifunctional gold nanorods

Abstract

Introduction: Treatment of cervical cancer, the third most prevalent cancer in women, is challenged by resistance to chemo and radio therapy, organ toxicities and disease relapse which is mainly due to undiagnosed small metastases and failure in monitoring the course of treatment. Imaging is therefore another critical aspect in overall cancer management. We designed a triple combination treatment modality involving photo thermal therapy, EGFR mAb and GW627368X, an EP4 prostanoid receptor antagonist in a single nanoprobe which also serves as an efficient X-ray CT contrast agents. Methodology: Stimuli responsive, GW627368X loaded, EGFR mAb tagged Gold Nanorods(GNRs) were prepared by seed mediated method and characterized by TEM, NMR, IR and UV absorption spectroscopy. Cellular uptake of nanoparticles was studied by flow cytometry and fluorescent imaging. Drug release kinetics was studied prior to in vitro study. Cervical cancer cells, SiHa and ME180, were incubated with GNRs for 45 mins, irradiated with cw-NIR laser (808 nm) for various time periods and incubated for 12 hours. Cellular effects were studied by viability assays, flow cytometry, florescent staining, SEM, ELISA and western blot analysis. The X-ray attenuation property of nanoprobe was demonstrated by CT imaging of GNR incubated cervical cancer cells compared with untreated cells. Results: Due to surface plasmone resonance of GNRs, energy from incident NIR rays are converted into heat inducing apoptosis evident in viability assays further confirmed by flow cytometry, microscopy and western blot. Accumulation of the GNRs around the EGFR overexpressing transformed cells and subsequent uptake was confirmed microscopically and by increase in SSC of cells. EGFR blockade disrupts ligand receptor interaction down regulating survival pathways like Ras/MAPK, PI3K/Akt and JAK/STAT. Stimuli dependent drug release inhibits EP4 receptor in turn down regulating COX-2, PI3K/Akt and angiogenesis. Reduced VEGF, EGF and PGE-2 production was confirmed by ELISA and down regulation of pAkt, pMAPK, pEGFR, COX-2 and EP4 proteins was confirmed by western blot analysis. Prominently distinguishable CT attenuation was obtained with gold nanoprobes compared to untreated cells. Conclusion: EGFR mAb tagged, GW627368X loaded GNRs is novel therapeutic approach merging multiple strategies in single nanoprobe. Besides targeted accumulation, EGFR mAb disrupts EGFR signaling which along with stimuli dependent drug release block multiple downstream pathways. Photothermal therapy is highly efficient, selective approach as NIR has high tissue permeability but is harmless to normal tissue. Moreover, high X-ray atteneuation of gold makes it suitable a CT contrast agent for both diagnosis and monitoring the course of treatment. The proposed modality would thus prove to be highly efficient in overall management of cervical cancer.