Activation of autophagy via bacterial lipopolysaccharide in breast cancer cells: A molecular approach to enhancing immunotherapeutic outcomes

Background : Autophagy plays a pivotal role in regulating cancer cell survival and death. Leveraging bacterial components, such as lipopolysaccharide (LPS), to modulate autophagy represents a novel strategy in oncologic therapeutics, especially in breast cancer. Objective : To assess the effect of LPS derived from Escherichia coli on the proliferation, viability, and immune signaling pathways in human breast cancer cell lines MCF-7 and MDA-MB-231, with a focus on autophagy induction and Toll-like receptor activation. Methods : LPS was isolated using the phenol–water method from E. coli strains ATCC 8739 and DH5α. Breast cancer cells were treated with varying concentrations of LPS over multiple time intervals (24–72 h). Viability was measured by MTT and CCK-8 assays, while mRNA expression levels of TLR-4, NF-κB, and PIK3C3 were quantified using qRT-PCR following RNA extraction and cDNA synthesis. Results : LPS treatment significantly reduced cell viability in both breast cancer cell lines in a time- and dose-dependent manner. Gene expression analysis revealed robust upregulation of TLR-4 and NF-κB, implicating activation of immune-related signaling. Moreover, increased PIK3C3 expression indicated stimulation of autophagic pathways. At the molecular level, there was an increase in the conversion of LC3-I to LC3-II and degradation of the autophagy substrate P62/SQSTM1, as confirmed by Western blot analysis, indicating enhanced autophagy. The findings confirm LPS’s ability to trigger immune–autophagic responses leading to cytotoxic effects in cancer cells. Conclusion : LPS from E. coli effectively induces autophagy and activates the immune pathway in breast cancer cells, highlighting its dual potential as an immunomodulator and cytotoxic agent. These findings support further exploration of LPS as an adjuvant in breast cancer treatment strategies, particularly in synergy with conventional chemotherapeutic agents.