en میکروب شناسی مولکولی Molecular Microbiology مقاله پژوهشی Original Research Article <p style="text-align: justify;"><span style="font-size:16px;"><span style="font-family:Times New Roman;"><b><span style="background:#1f497d"><span style="color:white"><span style="letter-spacing:-.1pt">Background and Aim:</span></span></span></b><span style="color:black"> Probiotics, particularly species of Bifidobacterium, have shown potential anticancer properties through mechanisms involving immune modulation, regulation of apoptosis, and production of bioactive metabolites. This study aimed to examine the cytotoxic effects of post-fermentation medium (PFM) and cell extract (CE) derived from <i>Bifidobacterium (B.) bifidum</i> on colorectal cancer (CRC) cells and to evaluate their impact on the expression of cancer-related microRNAs (miRNAs) and target genes.</span><span lang="EN-ID"><span style="color:black"></span></span><br> <b><span style="background:#1f497d"><span style="color:white"><span style="letter-spacing:-.1pt">Materials and Methods:</span></span></span></b><span style="color:black"> HT-29 colorectal cancer cells were exposed to different concentrations (0&ndash;50% v/v) of PFM and CE. Cytotoxicity was assessed using the MTT assay. The expression levels of miR-196a-5p and miR-196b-5p and their target genes (<i>HOXB8</i>, <i>IGF2BP3</i>, and <i>E2F7</i>) were quantified using RT-qPCR.</span><br> <b><span style="background:#1f497d"><span style="color:white"><span style="letter-spacing:-.1pt">Results:</span></span></span></b><span style="color:black"> PFM induced a dose-dependent reduction in HT-29 cell viability, with an IC₅₀ of approximately 35%, while CE displayed minimal cytotoxicity. PFM also upregulated miR-196a-5p and miR-196b-5p, particularly at 35% and 50%, whereas CE had no significant effect. Correspondingly, PFM was associated with significant downregulation expression of <i>HOXB8</i> and <i>IGF2BP3</i>. No meaningful changes were observed in <i>E2F7</i> expression or in CE-treated cells.</span><br> <b><span style="background:#1f497d"><span style="color:white"><span style="letter-spacing:-.1pt">Conclusion:</span></span></span></b><span style="color:black"> <i>Bifidobacterium bifidum</i>-derived PFM demonstrated anticancer activity by reducing cancer cell viability and showing an association with changes in miRNA and target gene expression. However, these findings are correlative and do not establish a causal, miRNA-mediated mechanism. Further functional studies (e.g., using miRNA mimics/inhibitors or gene knockdown) are required to determine whether the observed gene expression changes are directly mediated by miRNA modulation, and <i>in vivo</i> validation is also warranted.</span></span></span></p> Bifidobacterium bifidum, Colorectal Neoplasms, Fermentation Products, Gene Expression Regulation, MicroRNAs 1 11 http://ijmm.ir/browse.php?a_code=A-10-2922-1&slc_lang=en&sid=1 Arghavan Sabzevari arghavanas995@gmail.com 100319475328460034270 0009-0005-5512-1752 No Department of Biology, Payame Noor University (PNU), Tehran, Iran Somayeh Farahmand s.farahmand@pnu.ac.ir 100319475328460034271 100319475328460034271 Yes Department of Biology, Payame Noor University (PNU), Tehran, Iran Mohammad Amin Niknezhad M.a.niknezhad.71@gmail.com 100319475328460034272 0009-0001-9352-8482 No Department of Microbiology, Islamic Azad University, Shahrekord Branch, Shahrekord, Iran