Impact of Dairy and Plant-Based Milk Products on the Growth Dynamics of Triple- Negative Breast Cancer Cells in Vitro

Triple-negative breast cancer (TNBC) is the most common malignant tumor among Arab women, accounting for 18.8% of female cancer cases in Oman. TNBC lacks estrogen and progesterone receptors, as well as the Human Epidermal Growth Factor Receptor 2 (HER2). Its growth is stimulated by Insulin-Like Growth Factor 1 (IGF-1), which is secreted by the liver and found in blood, saliva, and milk. High levels of IGF-1 are found in tumor growth. Cow’s milk, a complex biological fluid, is known to increase systemic IGF-1, insulin, and estrogen signaling, which may contribute to breast cancer progression. This study investigated the effects of cow’s milk, soy milk, and almond milk on TNBC cell proliferation in vitro. It was hypothesized that cow’s milk would enhance cancer cell proliferation and IGF-1 levels, whereas soy and almond milk would have minimal effects. The MDA-MB-231 TNBC cell line was selected for this study. The experiment was divided into four groups: Cow’s Milk A, Cow’s Milk B (from two different commercial brands), and Almond milk, and Soy milk as a control. These four different types of milk were introduced into cultured cancer cells at 25 µL/mL, 50 µL/mL, 100 µL/mL, and 200 µL/mL concentrations, and incubated for 24 and 48 hours. Cell viability and proliferation were assessed using MMT assay. IGF-1 and IGF-1 receptors were measured using the ELISA technique which were compared to control samples. At 24 and 48 hours, Cow’s Milk A and B gradually increased cancer cell proliferation from 50 to 200 µL/mL concentrations. Conversely, almond and soy milk did not show an increase in cell proliferation with rising concentrations. These findings suggest that cow’s milk may promote TNBC cell proliferation through IGF-1 signaling, while plant-based alternatives may have a lesser impact. Additional research is necessary to better understand the influence of IGF-1 in cow’s milk on the development and progression of triple-negative breast cancer (TNBC).