LAUSR

Background: Leiomyosarcoma (LMS) is a malignant tumor of the uterine body that represents 40-60% of all gynecological sarcomas. Up to now, there is no specific treatment or diagnostic biomarkers for this tumor. The identification and characterization of miRNAs signature could help to its management. In addition, miRNAs represent targets for therapies due to their ability to modulate various signaling pathways simultaneously. Thus, the present study aimed to evaluate the effects of genetic manipulation of miR-34a and miR-181b on their predicted target genes in LMS cells. Methods: SK-UT-1 cells from uterine LMS were transfected with synthetic miRNA mimics and inhibitors (siRNA) of miR-34a and miR-181b. The efficacy of transfection was assessed by miRNA expression (qRT-PCR) assays. In order to identify potential genetic interactions network of miR-34a and 181b, predicted target genes were selected by in silico analysis (miRTargetLink 2.0 and miRDB). After SK-UT-1 cells transfection, the expression of target genes was evaluated by qRT-PCR. Results: SK-UT-1 cells showed greater efficiency of mimics and siRNA transfections after 48h treatment for both miR-34a and 181b. MDM4, TP53, BCL2, KMT2D, NOTCH2, and CCND1 were identified as predicted target genes of miR-34a; and the TIMP3, FGFR1, BCL2, NOTCH2, ATM, and IRS1 target genes for miR-181b. Expression profile of selected target genes was assessed after each treatment. The miR-34a mimic significantly increased the expression of MDM4 after 96h of treatment, while the BCL2 and TP53 showed an increase in expression with siRNA after 48h of treatment. CCND1 showed a greater expression in both treatments at 48h. An increase in KMT2D and NOTCH2 expression was also observed after treatment, even though without statistically significant. Treatment with miR-181b mimic led to increased FGFR1 expression within 72h. Although some expression alterations were observed in TIMP3, BCL2, NOTCH2, ATM, and IRS1 genes after mimic and siRNA treatments, there was no statistical significance. Conclusion: The effect of miR-34a upregulation leads to induction MDM4 and CCND1 expression, the first being a TP53 inhibitor and the second, responsible for cell cycle maintenance. The miR-34a downregulation had an inductor effect on expression of MDM4, BCL2 (apoptosis regulator), TP53 (tumor suppressor), and CCND1. The miR-181b upregulation induced the expression of fibroblast growth factor receptor, FGFR1. In uterine LMS cells, miR-34a seems to exert an important role in regulating the expression of cell cycle and apoptosis-related genes. Citation Format: Bruna C. de Almeida, Laura G. dos Anjos, Katia C. Carvalho. Effects of miR-34a-5p and miR-181b-5p silencing and induction on their potential targets in uterine leiomyosarcoma cells. [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 4749.