This study evaluated the role of arginine vasopressin (AVP) in modulating proliferation and cell-death pathways in an invasive triple-negative breast cancer model. AVP is ectopically expressed in breast cancer and, via G protein–coupled receptors such as V1A, can trigger mitogenic signalling in various cell types. The authors examined whether AVP influences proliferation of MDA-MB-231 cells (a triple-negative breast cancer cell line that expresses V1A) and whether AVP alters responses to inhibitors of endocytosis and PI3K signalling.
MDA-MB-231 cells were exposed to 100 nM AVP for 24 hours either alone or combined with Dynasore (DYN), a selective inhibitor of Dynamin 2 GTPase involved in membrane receptor endocytosis. Parallel experiments used the PI3K pathway inhibitor wortmannin (Wort) alone or in combination with DYN. Endpoints included cytotoxicity, apoptosis, autophagy-mediated cell death, cell cycle progression, migration and invasion assays, and expression of a multidrug resistance gene. Signalling pathway activation (notably AKT) and specific molecular markers were assessed to link phenotype to mechanism.
Exposure to AVP alone induced apoptosis in about 20% of the MDA-MB-231 cell population. When AVP was combined with DYN, apoptotic cells increased to approximately 28%, indicating that dynamin inhibition potentiated AVP-driven apoptosis. Treatment with wortmannin alone induced apoptosis in 29% of cells; combining wortmannin with DYN further increased apoptosis to 35%. Apoptotic responses were associated with increased expression of the pro-apoptotic proteins Bax and Caspase-3, consistent with activation of intrinsic and executioner apoptotic pathways in these treatment conditions.
Treated cells demonstrated cell cycle arrest in the G0/G1 phase, consistent with reduced proliferative capacity after AVP, AVP+DYN, Wort, and Wort+DYN exposures. In functional assays, both migration and invasion of MDA-MB-231 cells were reduced following AVP treatment and in combined-treatment conditions, indicating that AVP and dynamin or PI3K pathway inhibition impair motility and invasive behavior in this model.
Autophagy-related markers showed differential regulation depending on the treatment. The microtubule-associated protein LC3II and Beclin1 mRNA increased in cells treated with AVP and AVP+DYN, suggesting induction or enhancement of autophagy-related processes in these groups. In contrast, LC3II and Beclin1 expression decreased in Wort and Wort+DYN treatments, indicating that PI3K inhibition with wortmannin suppresses these autophagy markers in this context. These findings highlight that AVP and PI3K pathway blockade have opposing effects on autophagy marker expression in MDA-MB-231 cells.
Mechanistically, combined treatments (both AVP+DYN and Wort+DYN) were reported to reduce AKT activation, linking decreased survival signalling to the observed increase in apoptosis. Dual treatments also downregulated the multidrug resistance gene MDR1, which may have implications for chemosensitivity although drug-response assays beyond MDR1 expression were not detailed in the abstract. The coordinated decrease in AKT signalling and MDR1 expression provides a molecular rationale for the enhanced antiproliferative and pro-apoptotic effects seen with combined inhibitor regimens.
The authors conclude that AVP can induce both apoptosis and autophagy-related cell death in an invasive triple-negative breast cancer cell line and that AVP potentiates the antiproliferative effect of dynamin inhibition with Dynasore. Wortmannin similarly showed enhanced apoptosis when combined with Dynasore. Dual treatment modalities decreased AKT activity and downregulated MDR1, consistent with reduced survival signalling and drug-resistance marker expression. The study was approved by the ethical committee of the Faculty of Science, Tanta University (Approval code: 3425/11/20). No competing interests were declared by the authors.
Limitations and additional details beyond those reported in the abstract (for example, precise assay methods, quantitative measures of cell viability beyond apoptosis percentages, or in vivo validation) were not reported in the source material provided here.