Melatonin at the Interface of Ovarian Cancer and Mesenchymal Stem Cells: Molecular Mechanisms and Therapeutic Perspectives

• Grant number: 25/03607-0
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2025
• End date: August 31, 2028
• Field of knowledge: Biological Sciences - Morphology - Anatomy
• Principal Investigator: Luiz Gustavo de Almeida Chuffa
• Grantee: Luiz Gustavo de Almeida Chuffa
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• City of the host institution: Botucatu
• Associated researchers: Debora Aparecida Pires de Campos Zuccari ; Fábio Rodrigues Ferreira Seiva ; Lucilene Delazari dos Santos ; Vinicius Augusto Simao

Abstract

Ovarian cancer (OC) is the most lethal gynecological malignancy, characterized by high recurrence rates, disease progression, and frequent development of chemoresistance. The tumor microenvironment consists of heterogeneous cell populations, where tumor growth is driven by a subset of specialized cells known as cancer stem cells (CSCs), distinguished by their self-renewal and multipotent capabilities. CSCs may originate from mesenchymal stem cells (MSCs), such as human adipose tissue-derived MSCs (hAT-MSCs), which can undergo malignant transformation into CSCs or cancer-associated fibroblasts (CAFs) through factors secreted by cancer cells, primarily via small extracellular vesicles known as exosomes. This transformation contributes to more aggressive and chemoresistant OC phenotypes. Melatonin, a hormone secreted by the pineal gland in a circadian manner and by peripheral tissues non-circadianly, has shown antitumor potential due to its pro-oxidant, immunomodulatory, antiangiogenic, and pro-apoptotic properties, effectively suppressing CSC and CAF activity. Additionally, conditioned medium (CM) and exosomes derived from hAT-MSCs treated with Paclitaxel (PTX) have demonstrated efficacy in inhibiting cancer cells in both in vitro and in vivo studies across various tumor types. This study aims to investigate melatonin's role in modulating the neoplastic differentiation of hAT-MSCs induced by ovarian cancer cells (SKOV-3 and OVCAR-3) and explore the therapeutic potential of melatonin-treated hAT-MSCs and their derived exosomes in tumor progression. In vitro experiments will assess the effects of CM from each cell line on the others, with or without melatonin and PTX treatments, using both independent cultures and indirect co-culture systems. Ovarian cancer cells will also be cultured under non-adherent conditions to evaluate multicellular tumor spheroid (MCTS) formation and treatment with melatonin- and PTX-treated hAT-MSCs or their CM. Subsequently, hAT-MSCs will be treated with melatonin or PTX, and their CM and isolated exosomes will be administered in an in vivo drug delivery model using BALB/c-nude mice with induced OC. Cell viability, cytotoxicity, migration, invasion, and apoptosis will be assessed, along with immunostaining and protein quantification of markers related to CSC and CAF differentiation. Multiplex assays will evaluate target proteins in CM, while melatonin and its precursors will be detected via immunogold labeling. Exosomes will undergo transmission electron microscopy (TEM) for ultrastructural characterization, nanoparticle tracking analysis (NTA), and mass spectrometry to profile their proteomic, metabolomic, and transcriptomic contents. This comprehensive approach aims to elucidate melatonin's therapeutic potential against OC, its role in modulating hAT-MSC behavior, and its capacity to inhibit tumor progression. Ultimately, the study seeks to establish an effective drug-delivery methodology combining hAT-MSCs and melatonin for OC treatment. (AU)