Abstract PO-233: Effect of Lactobacillus on tumor growth and radiosensitivity

Abstract

Abstract Cervical cancer is the most common HPV-associated cancer as it is diagnosed in more than half a million women a year. It specially affects low and middle-income countries. In terms of treatment options, microbiome may be a key element in achieving the desired effect of radiation treatment in cervical cancer. The objective here is to evaluate the effect of Lactobacillus iners on tumor growth and cell response to radiation therapy. A previous test cohort identified that poor responders had an abundance of the Lactobacillus genus in their microbiome, while early/exceptional responders had other microorganisms such as Porphyromonas augmented. Moreover, whole genome shot gun sequencing (WGS) demonstrated that Lactobacillus iners is the most common species of Lactobacillus in cervical samples of poor responders and is absent in exceptional responders. Based on these findings, we propose that Lactobacillus iners creates a microenvironment which supports tumor growth and facilitates resistance to radiation therapy. A clonogenics assay using SiHa, HeLa and CaSki cell lines with three bacterial supernatants at different radiation doses was performed. While another facet of our research was comparing tumor growth in C57 mice receiving Lactobacillus iners suspension and those not receiving it. In terms of the clonogenics assay: L. crispatus and L. iners supernatants may increase radiosensitivity of SiHa, HeLa, and CaSki cell lines. Cell survival may also be affected by nutrients in bacterial broths. In terms of the mice's tumors analyzed: no significant differences in tumor growth were found between the control and treatment groups. L. crispatus cohort showed tumor regression, which correlates with higher populations of innate immune cells. Further clonogenic and in vivo experiments are supported to obtain more precise results that could eventually be applied in radiation oncology treatments. Citation Format: Laura P. Reguero-Cadilla, Ann Klopp. Effect of Lactobacillus on tumor growth and radiosensitivity [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-233.