Abstract 2779: The significance of TIMP-1 and hypoxia in cancer stemness: A synergistic role in chemoresistance

Abstract

Abstract Chemotherapeutic resistance in non-small-cell lung cancer (NSCLC) poses a formidable clinical challenge. Numerous studies have highlighted the critical role of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in tumorigenesis and, increasingly, in the development of chemoresistance. We have studied multiple aspects of the MMP-independent, tumor-promoting function of TIMP1 in human NSCLC. Our recent studies have found a pivotal role for TIMP1 in chemoresistance. In order to gain an enhanced comprehension of the mechanisms underpinning TIMP-1-mediated chemoresistance, we have sought to determine the contribution of CSCs and hypoxia. TIMP-1 plays a role in propagating stemness, although relatively unexplored in the context of CSCs within NSCLC. A second crucial factor in the development of chemoresistance in NSCLC is the interplay between intratumoral hypoxia and CSCs. As the tumor grows, metabolic demand for oxygen increases and hypoxic regions are seen in areas furthest from the blood vessels. We have shown TIMP1 levels to increase under experimentally-induced hypoxia. In the present study, we cultured NSCLC cell lines and their TIMP1 KD clones in an assay with serum-free media and found a significant decrease in spheroid size in TIMP1 KD clones. Postulating a reduction in CSC population in KD clones, we determined the NSCLC CSC markers CD133 and ALDH’s expression in the NT and KD TIMP1 clones. Flow cytometry results showed that CD133pos and ALDHhigh populations were significantly decreased in TIMP1 KD clones relative to NT clones. Moreover, KD clone of TIMP1 showed a decrease in the levels of CSC-specific Transcription factors Oct 4A and Nanog. Taken together, our findings confirm that reduction in TIMP1 expression negatively impacts CSC populations. Furthermore, we determined the mRNA levels of CD44, another CSC marker also expressed in lung cancer is upregulated under hypoxia (1% O2) in both the NT and KD clones of TIMP1. Thus, we postulate that TIMP1 enhances chemoresistance by promoting CSC propagation within a hypoxic tumor microenvironment. Citation Format: Ilamathi Thirusenthilarasan, Wei Xiao, Mumtaz V. Rojiani. The significance of TIMP-1 and hypoxia in cancer stemness: A synergistic role in chemoresistance [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 2779.