AbstractBreast cancer stem cells (BCSCs) resist conventional treatments and cause tumor recurrence. Almost 25% of breast cancers overexpress human epidermal growth factor receptor-2 (HER2). Here we developed a novel multi-targeted nanosystem to specifically eradicate HER2+ BCSCs. Plasmids containing CXCR1 promoter, PE38 toxin, and 5′UTR of the basic fibroblast growth factor-2 (bFGF 5'UTR) were constructed. Polyamidoamine (PAMAM) dendrimers functionalized with anti-HER2 VHHs were used for plasmid delivery. Stem cell proportion of MDA-MB-231, MDA-MB-231/HER2+ and MCF-10A were evaluated by mammosphere formation assay. Hanging drop technique was used to produce spheroids. The uptake, gene expression, and killing efficacy of the multi-targeted nanosystem were evaluated in both monolayer and spheroid culture. MDA-MB-231/HER2+ had higher ability to form mammosphere compared to MCF-10A. Our multi-targeted nanosystem efficiently inhibited the mammosphere formation of MDA-MB-231 and MDA-MB-231/HER2+ cells, while it was unable to prevent the mammosphere formation of MCF-10A. In the hanging drop culture, MDA-MB-231/HER+ generated compact well-rounded spheroids, while MCF-10A failed to form compact cellular masses. The multi-targeted nanosystem showed much better uptake, higher PE38 expression, and subsequent cell death in MDA-MB-231/HER2+ compared to MCF-10A. However, the efficacy of our targeted toxin gene therapy was lower in MDA-MB-231/HER2+ spheroids compared with that in the monolayer culture. the combination of the cell surface, transcriptional, and translational targeting increased the stringency of the treatment.
Targeted Toxin Gene Therapy Of Breast Cancer Stem Cells Using CXCR1 Promoter And bFGF 5′UTR
