Enhancing chemosensitivity of wild-type and drug-resistant MDA-MB-231 triple-negative breast cancer cell line to doxorubicin by silencing of STAT 3, Notch-1, and ß-catenin genes.

BACKGROUND/OBJECTIVE: The absence of receptors in triple-negative breast cancer limits therapeutic choices utilized in clinical management of the disease. Doxorubicin is an important member of therapeutic regimens that is hindered by emergence of resistance. The current work aim to investigate of therapeutic potential of single and combinations of siRNA molecules designed for silencing STAT 3, Notch-1, and ß-catenin genes in wild type and doxorubicin resistant MDA-MB-231 triple negative breast cancer cell line. METHODS: Doxorubicin resistant MDA-MB-231 cell line was developed and characterized for the expression of multidrug resistance-related genes, CD44/CD24 markers, inflammatory cytokines, and the expression of STAT 3, Notch-1, and ß-catenin targeted genes. Further, the effect of single and combinations of siRNA on cell viability and chemosensitivity of both wild type MDA-MB-231 cells (MDA-MB-231/WT) and doxorubicin resistant MDA-MB-231 cells (MDA-MB-231/DR250) were assessed by MTT assay. RESULTS: The IC50 of doxorubicin was 10-folds higher in MDA-MB-231/DR250 resistant cells compared to MDA-MB-231/WT control cells, 1.53 ± 0.24 µM compared to 0.16 ± 0.02 µM, respectively. The expression of targeted genes was higher in resistant cells compared to control cells, 3.6 ± 0.16 folds increase in ß-catenin, 2.7 ± 0.09 folds increase in Notch-1, and 1.8 ± 0.09 folds increase in STAT-3. Following treatment with siRNAs, there was a variable reduction in mRNA expression of each of the targeted genes compared to scrambled siRNA and a reduction in IC50 in both cell lines. The effect of a combination of three genes produced the largest reduction in IC50 in resistant cell line. CONCLUSION: Our study showed that the silencing of single and multiple genes involved in drug resistance and tumor progression by siRNA can enhance the chemosensitivity of cancer cells to conventional chemotherapy.

Grafting of anti-nucleolin aptamer into preformed and remotely loaded liposomes through aptamer-cholesterol post-insertion.

A new combination strategy of an active loading and active targeting approach was applied in this work. The liposomes actively loaded with Curcumin (CRM) (LipCRM) were decorated with cholesterol tagged-anti-nucleolin AS1411 aptamer (NCL) via a new post-insertion approach, utilizing the cholesterol as a wedge to incorporate aptamer into the surface of the liposome bilayer. A successful NCL post-insertion was verified by agarose gel electrophoresis and dynamic light scattering (DLS). The cellular uptake of AptNCL-Lip was investigated using flow cytometry and Confocal Laser Scanning Microscopy (CLSM) on two different human breast cancer cell lines (MCF-7 and MDA-MB-231). The uptake and cytotoxicity of loaded CRM were investigated using flow cytometry and MTT assay. Our results showed successful post insertion of NCL aptamer to the surface of Lip. Also, higher cellular uptake was noted for AptNCL-Alexa-LipRhod compared to blank LipRhod in both cell lines. Moreover, CLSM showed prominent endocytosis and uptake of AptNCL-Alexa-LipRhod into the cytoplasm of breast cancer cells. Furthermore, the results showed a significant increase in the uptake and cytotoxicity of AptNCL-LipCRM compared to LipCRM in both cell lines. Overall, our results demonstrate a successful post-insertion of cholesterol-tagged aptamer into liposomes and the possible combination between active loading and active targeting.