interleukin-12 inhibits tumor growth and metastasis promoted by tumor-associated mesenchymal stem cells in triple-negative breast cancer

Objective: the aim of this study was to understand the interactions between tumor-associated mesenchymal stemcells (ta-mscs) and triple-negative breast cancer (tnbc) cells, which appear to be necessary for developing effectivetherapies.materials and methods: in this experimental study, mda-mb-231 and 4t1 tnbc cells were co-cultured with bonemarrow-derived mscs, and ta-mscs conditioned media (cm) were collected. ta-msc cm-treated tnbc cells weresubjected to migration and invasion assays. epithelial-mesenchymal transition (emt) marker expression was quantifiedby real-time polymerase chain reaction (rt-pcr). cell proliferation was measured using trypan blue exclusiontechnique, while cell cycle distribution and apoptosis were assessed by flow cytometry. the effects of ta-mscs ontumor volume, survival rate, and lung metastasis were evaluated by subcutaneous co-injection of mscs with 4t1 cellsin the right flanks of balb/c mice (n=5 per group). intratumoral interleukin-12 (il-12) immunotherapy was performedusing lentiviral particles as a rescue experiment. the ta-mscs rna-seq dataset (prjeb27694) was analyzed todetect elevated metastasis-associated oncogenes, downloaded from the european nucleotide archive database. forvalidation of the rna-seq data analysis, the expression levels of candidate oncogenes were evaluated in ta-mscs,tnbc cells, and tumor tissue using rt-pcr.results: ta-mscs enhanced migration, invasion, and emt of tnbc cells in vitro without affecting cell proliferation orapoptosis. in vivo, ta-mscs increased tumor growth and lung metastasis, while decreasing survival rates. il-12 therapyelevated serum il-12 and interferon-gamma (ifn-γ) expression, suppressed tumor volume and lung metastasis, andimproved overall survival in the ta-msc group. rna-seq data analysis identified upregulated oncogenes in ta-mscs,among which mmp3, cxcl2, cxcl5, and icam1 were selected as the most relevant to metastasis. these genesshowed increased expression in ta-mscs, tnbc cells, and tumor tissues.conclusion: the findings of the present study revealed a complex interplay between ta-mscs and tnbc cells thataffects tumor growth and metastasis. preclinical results indicate that intratumoral il-12 immunotherapy shows promisein overcoming ta-msc-promoted tumor growth and metastasis.