Abstract PD2-10: MiR-150 expression in breast cancer cells attract infiltration of lymphocytes to tumor microenvironment and is associated with better survival of the patients
Authors: Oshi Masanori , Maiti Aparna , Vaghjiani Raj.G , Wu Rongrong , Yan Li , Yamada Akimitsu , Hait Nitai , Ishikawa Takashi , Endo Itaru , Takabe Kazuaki , Tokumaru Yoshihisa 
Published: March 2023

MicroRNA (miRNA) are known as a key player in tumor biology and is shown to epigenetically regulate a large number of protein-coding genes, including tumor-related genes. MiR-150, a hematopoietic cell-specific miRNA, has been suggested to have various effects on cell proliferation, differentiation, apoptosis, migration, and invasion. However, there has been no study that investigated the role of miR-150 in the tumor microenvironment (TME) of breast cancer patients. We hypothesized that miR-150 expressed in breast cancer cells attract infiltration of lymphocytes to tumor microenvironment and is associated with better survival of the patients. In silico analyses of 1961 breast cancer patients were performed using multiple independent large cohorts, and in vitro studies by overexpressing miR-150 using its mimic in triple negative breast cancer (TNBC) cell lines were conducted. We found that miR-150 expression in patient breast tumors were strongly correlated with immune-related gene set scores, Allograft rejection, IL6/JAK/STAT3 signaling, Interferon-γ response, Inflammatory response, IL2/STAT5 signaling, and complement, in Hallmark collection of gene set variation analyses consistently in both METABRIC and TCGA cohorts (all spearman’s rank correlation coefficient (r) &gt; 0.50, all p &lt; 0.01). MiR-150 expression was also strongly correlated with cytolytic activity (CYT) score in both cohorts (r = 0.824 and 0.786, respectively, both p &lt; 0.01). Furthermore, miR-150 expression was significantly correlated with infiltrating fraction of CD8+ T cells (r = 0.799 and 0.525, respectively), CD4+ memory T cells (r = 0.759 and 0.656, respectively), dendritic cells (r = 0.735 and 0.696, respectively), and B cells (r = 0.759 and 0.576, respectively), as well as mRNA expression of major immune checkpoint molecules, including PD-1, CTLA4, IDO1, TIGIT, BTLA, and LAG3, in both cohorts (all r &gt; 0.50, and all p &lt; 0.01). MiR-150 expression in triple negative breast cancer (TNBC) was the highest among the subtypes (both p &lt; 0.001). MiR-150 expression level was significantly correlated with Nottingham histologic grade (both p &lt; 0.001). MiR-150 high tumor enriched not only immune-related gene sets but also apoptosis, KRAS signaling up, MTORC1, and p53 pathway by gene set enrichment analysis in both cohorts. High miR-150 expression patients were significantly associated with better overall survival (OS) in both cohorts (p &lt; 0.001 and p = 0.030, respectively). Subgroup analysis revealed that a high miR-150 was associated with better OS in ER-positive/HER2-negative breast cancer in both cohorts (p = 0.002 and 0.044, respectively), and in TNBC in the METABRIC cohort (p = 0.006). Unexpectedly, overexpression of miR-150 by its mimic shown no significant effect on cell proliferation, migration, nor invasion consistently in two TNBC cell lines. On the other hand, overexpression of miR-150 by its mimic significantly attracted Jurkart immortalized lymphocytes consistently in two cell lines, which effect was abolished by addition of miR-150 inhibitor. Finally, we found that mimic overexpression of miR-150 significantly expressed multiple cytokines and multiple inflammatory signaling pathways which at least partially explained the increased attraction of T cells in patient samples and in vitro condition. In conclusion, miR-150 expression in breast cancer cells may be associated with better patient survival outcomes by attracting and activating immune cells in breast cancer TME.

Citation Format: Masanori Oshi, Aparna Maiti, Raj.G Vaghjiani, Rongrong Wu, Li Yan, Akimitsu Yamada, Nitai Hait, Takashi Ishikawa, Itaru Endo, Kazuaki Takabe, Yoshihisa Tokumaru. MiR-150 expression in breast cancer cells attract infiltration of lymphocytes to tumor microenvironment and is associated with better survival of the patients [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD2-10.