Abstract 1630: Development of a clinically relevant in vitro model of chemo-radioresistant cervical cancer cells for insights into treatment resistance
Authors: Khurana Sanchita , Singla Surbhi , Sharma Reena , Rai Bhavana , Bhattacharyya Shalmoli 
Published: June 2022

Abstract
Resistance to therapeutic treatment is a common phenomenon that contributes to relapse in several cancers including cervical that is the fourth most common cancer in women across the world. Acquired resistance to chemotherapy, radiotherapy or their combination contributes to a majority of relapse cases which suggests the need to develop models that can be used for preliminary screening of drugs or decipher the associated signaling mechanisms contributing to this resistance. Various chemo-resistant, as well as radio-resistant models, have been established as in vitro models. In cervical cancer treatment, often, radiation therapy is accompanied by the addition of radio-sensitizers such as cisplatin that increase its treatment efficiency. Hence, a combined chemo-radio-resistant in vitro model seems more relevant clinically in cervical cancer. Therefore, we designed our study to establish a cellular model that is resistant to a combined treatment of chemotherapy and radiotherapy. A chemo-radio resistant cervical cancer cell line (HeLa) was developed in vitro by a fractionated exposure of a combination of cisplatin and megavoltage X-rays. Briefly, HeLa cells were sensitized with cisplatin (0.1µM increase at every fraction) prior to radiation exposure (2Gy). The cells were treated once in 5 days and eventually after 25 fractions, delivered in 20 weeks, the cells were made resistant up to a total dose of 2.5µM cisplatin + 50Gy. These cells were further characterized and compared with radioresistant HeLa cells as well as parental cells. For this purpose, proliferation assay, clonogenic survival assay, cell cycle analysis and apoptosis assay were performed. The resistivity was confirmed by comet assay and Gamma-H2AX staining. Interestingly, an increase in cell proliferation and clonogenic survival rates was observed in chemo-radio-resistant cells. FACS analysis revealed that the proportion of cells in G2/M phase increased and apoptotic rates declined in chemo-radio-resistant cells. Further, changes in comet tails, olive moment and Gamma-H2AX foci formation in chemo-radio-resistant groups confirmed resistivity. These cells were also analyzed for their metastatic properties and results suggest that induced chemo-radio-resistant cells are more tumorigenic as compared to only radioresistant cells as well as the parental ones. In conclusion, the establishment of a chemo-radio-resistant cell line may serve as a model to study signalling mechanisms, drug screening and develop novel drugs. Further studies are underway to induce the chemo-radio resistance in other cell lines by a similar method.
Citation Format: Sanchita Khurana, Surbhi Singla, Reena Sharma, Bhavana Rai, Shalmoli Bhattacharyya. Development of a clinically relevant in vitro model of chemo-radioresistant cervical cancer cells for insights into treatment resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1630.