Prodigiosin-Functionalized Probiotic Ghosts as a Bioinspired Combination Against Colorectal Cancer Cells

Lactobacillus acidophilus ghosts (LAGs) with the unique safety of a probiotic, inherent tropism for colon cells, and multiple bioactivities offer promise as drug carriers for colon targeting. Our objective was to evaluate LAGs functionalized with prodigiosin (PG), apoptotic secondary bacterial metabolite, as a bioinspired formulation against colorectal cancer (CRC). LAGs were prepared by a chemical method and highly purified by density gradient centrifugation. LAGs were characterized by microscopic and staining techniques as relatively small-sized uniform vesicles (≈1.6 µm), nearly devoid of cytoplasmic and genetic materials and having a negatively charged intact envelope. PG was highly bound to LAGs envelope, generating a physiologically stable bioactive entity (PG-LAGs), as verified by multiple microscopic techniques and lack of PG release under physiological conditions. PG-LAGs were active against HCT116 CRC cells at both the cellular and molecular levels. Cell viability data highlighted the cytotoxicity of PG and LAGs and LAGs-induced enhancement of PG selectivity for HCT116 cells, anticipating dose reduction for PG and LAGs. Molecularly, expression of the apoptotic caspase 3 and P53 biomarkers in HCT116 intracellular proteins was significantly upregulated while that of the anti-apoptotic Bcl-2 (B-cell lymphoma 2) was downregulated by PG-LAGs relative to PG and 5-fluorouracil. PG-LAGs provide a novel bacteria-based combination for anticancer biomedicine. Graphical abstract