Abstract 389: The role of endoplasmic reticulum stress in immune surveillance and effectiveness of immunotherapy in renal and ovarian carcinoma
Authors: Svoboda Marek , Moran Lukas , Vavrusakova Barbora , Krejci Lenka , Souckova Kamila , Vasickova Katerina , Holanek Milos 
Published: March 2024

Abstract
In complex tumor-host interactions, the immune response has a dual role, with the capacity to both promote and suppress tumor growth, requiring complex interactions of regulatory molecules within the cellular network of the tumor-immune microenvironment (TIME). Various factors in TIME, such as low pH and hypoxia, cause Endoplasmic Reticulum Stress (ERS). Immune cells exposed to ERS lack antigen presentation, exhibit a suppressor phenotype, and can initiate apoptosis. Therefore, relieving ERS can benefit immune surveillance and response to immunotherapy. Our research is focused on tumor-immune cells interaction, specifically in ovarian and renal cancers. We conducted in vitro co-cultures of these cancer cells with peripheral blood mononuclear cells (PBMC) and manipulated ERS using a well-established ERS inducer tunicamycin and a chemical chaperone tauroursodeoxycholic acid (TUDCA). We then employed various techniques such as MTT, RT-qPCR, western blotting, immunofluorescence staining, scratch wound assay, and 3D co-cultures to analyze cellular viability, gene expression, protein levels of ERS markers (e.g., BiP, CHOP, PERK), immune cell activity (e.g., IL-2, INFγ, FoxP3, PD-1), migration, invasiveness, interaction, spheroid formation, and immune cell infiltration. Furthermore, we examined ERS and immune profiles in tumor samples from patients with ovarian and renal cancer who underwent conventional therapy or immunotherapy.Relieving ERS increased the infiltration of PBMC into tumor spheroids and reduced the expression of BiP and PERK in PBMC. In vitro, the viability of ovarian and renal cancer cells increased when cultured alone after ERS alleviation. However, when co-cultured with PBMC, their viability decreased, indicating enhanced immune cell response. Additionally, the growth and migration of ovarian and renal cancer cells were limited in these co-cultures, along with increased expression of BiP and CHOP and an elevated CHOP/BiP ratio. We connected these findings to the molecular background of ERS in patient samples and observed a positive correlation between a favorable clinical outcome, higher lymphocyte infiltration at the tumor site, and increased levels of BiP and CHOP in cancer cells. We further applied these results to OC and RCC in vivo syngeneic mouse models, currently with very promising outcomes.Based on these results we expect ERS alleviation as a suitable approach to improving the survival and effectiveness of immune cell populations within hostile tumor-induced microenvironment with positive effects on anticancer immunotherapy. Supported by Ministry of Health of the Czech Republic, grant nr. NU21-03-00539, and by the Johannes Amos Comenius Programme, project SALVAGE nr. CZ.02.01.01/00/22_008/0004644. All rights reserved.
Citation Format: Marek Svoboda, Lukas Moran, Barbora Vavrusakova, Lenka Krejci, Kamila Souckova, Katerina Vasickova, Milos Holanek. The role of endoplasmic reticulum stress in immune surveillance and effectiveness of immunotherapy in renal and ovarian carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 389.