LAUSR

Cellular senescence and the associated secretory phenotype (SASP) promote cancer. During the process of aging, cellular and molecular changes that occur in non-cancerous cells can alter responses to cancer therapy and immune response in the tumor microenvironment (TME). Targeting senescent cancer-associated fibroblasts (CAFs) by means of removal, modulation of the SASP, or through cellular reprogramming represent therapeutic avenues for treating cancer. Heterogeneity of CAFs is emerging as an important area of investigation in cancer therapy. To better elucidate the interplay between cancer cells, immune cells, and senescent fibroblasts from different tissues and determine their impact on tumor growth and response to cancer therapy, we investigated the heterogeneity of cytokine secretion in senescent fibroblasts by a single cell cytokine assay. Control and treated proliferating and senescent fibroblasts were loaded onto IsoPlexis IsoCode chips coated with multiplexed antibodies which allows detection of 32 cytokines at a single-cell level for frequency and intensity. The Polyfunctional Strength Index (PSI) showed that stimulatory and chemo-attractant cytokines were dominant in the senescent fibroblasts. The Polyfunctional heat map showed that there are subpopulations of cells which have polyfunctional cytokine secretion (>2 different cytokines) in live senescent IMR90 cells. Treatment with ONC201 reduced cytokine polyfunctionality in live senescent IMR90 cells. Although ABT-263 (small molecule inhibitor of Bcl-2, Bcl-XL) did not show a significant reduction of polyfunctionality in live senescent IMR90, the frequency showed that ABT-263 reduced the secretion frequency of live senescent IMR90 cells except for GM-CSF. Combining ONC201 and ABT-263 diminished polyfunctionality and secretion frequency of senescent IMR90 cells except for MIF which was detected in 1.5% of the cells. Single cell cytokine profiling of live cells in the complex tumor microenvironment is providing insights into tumor progression, therapy resistance, and the effects of senolytic drugs and drug combinations. Citation Format: Lanlan Zhou, Shengliang Zhang, Kelsey E. Huntington, Benedito A. Carneiro, Wafik S. El-Deiry. Heterogeneity of cytokine secretion in single senescent fibroblasts is impacted by ONC201 and ABT-263 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2518.