Bitter melon extract affects cell-extracellular matrix interaction in human metastatic breast cancer cells

Abstract

Introduction: Bitter melon extract (BME) is known to exhibit cytotoxic effects on breast cancer cells (MCF-7). However, the molecular mechanisms by which BME exerts cytotoxic effects are not established. Integrins (which are transmembrane cell surface proteins) are universally expressed in all cell types and play critical roles in anchoring cells to the extracellular matrix and hence their survival. Integrin proteins when activated in turn activates a cascade of intracellular signaling steps (such as activation of focal adhesion kinase, FAK) which facilitates cell attachment, migration, survival, division etc. Aims: We aimed to investigate if BME exerts cytotoxic effects on MCF-7 cells via inhibiting attachment of cells to the extracellular matrix. We hypothesized that BME decreases expression of integrins and hence activation of FAK leading to cell cytoxicity. Methods: Fresh bitter melons were purchased from an Asian grocery store and the extract (BME) was extracted, centrifuged, and filter sterilized. The MCF-7 cells were cultured in DMEM medium with 1% BME (v/v). After culturing cells for 48 hours, pictures of cultures were taken to confirm cytotoxic effects on cells. In our earlier experiments, BME induced decrease in cell viability was also confirmed using Trypan blue exclusion and MTT assays. The cells were harvested and changes in the protein expression of β1-integrin and phospho-FAK (activated FAK) were determined using anti-β1-integrin and anti-phospho-FAK antibodies in the western blotting. Results & Discussion: BME exerted cytotoxic effects on MCF-cells (N=4). BME also reduced expression level of β1-integrin protein by more than 50% (N=3 with duplicate gels). Also, BME reduced expression of phospho-Tyr 397-FAK to below 20% (N=3), and total FAK to below 40% (N=3). The loading control protein GAPDH was not affected by the BME treatment (N=3). The data together supports our hypothesis. In the future, we will be running more sets of experiments to confirm our findings. FRD-MUCOM. All authors contributed equally to this work. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.