<p>Connexin 43 Modulates the Cellular Resistance to Paclitaxel via Targeting β-Tubulin in Triple-Negative Breast Cancer</p>

Abstract

Background: Triple-negative breast cancer has become an intricate part and hotspot in the clinical and experimental research. Connexins, serving as functional proteins in gap junctions, play an important role in tumorigenesis, cell proliferation and metastasis. Methods: We constructed and employed the Connexin 43 (Cx43) overexpression lentiviral vectors and Cx43 siRNA in paclitaxel-treated MDA-MB-231 cells. We performed the experiments of clonal formation and flow cytometry to gauge the effect of paclitaxel on cellular behaviors and immunofluorescence and subsequent quantitative RT-PCR and Western blot to examine the expression of genes and corresponding proteins. Experiments of scrape loading/dye transfer were utilized to explore the gap junctions. The targets of Cx43 were identified via the experiments of co-immunoprecipitation (Co-IP), GST pull-down assays and proximal ligation assay (PLA). Results: The results showed that Cx43 hindered cell proliferation and promoted apoptosis in the paclitaxel-treated MDA-MB-231 cells. Overexpressed Cx43 suppressed the expression of resistance genes such as BRCP, Txr-1, α-tubulin and β-tubulin and promoted the expression of apoptosis gene as TSP-1 and Bcl-2. Cx43 was also positively related to ITGα9 and negatively related to ITGαV and ITGα11. The gap junctions altered magnificently under different expressions of Cx43, which indicated that Cx43 could promote the number of intercellular gap junctions. The immunofluorescent experiment revealed that both of Cx43 and β-tubulin were mainly localized in the cytoplasm. The assays of Co-IP and GST pull-down demonstrated that there existed a direct interaction between Cx43 and β-tubulin. Furthermore, the result of PLA also showed that Cx43 interacts with β-tubulin in MDA-MB-231 cells. Conclusion: Overexpression of Cx43 could modulate the cellular resistance to paclitaxel via targeting β-tubulin in triple-negative breast cancer.

Pathogenesis and Clinical Significance of In-Stent Restenosis in Patients with Diabetes

“…The overexpression of Cx43 was shown to suppress the expression of genes associated with resistance to paclitaxel, such as genes encoding breast cancer resistance protein (BCRP), transcriptional factor Txr-1, α-tubulin, and β-tubulin, and, on the other hand, it promotes the expression of the genes of apoptosis such as Tsp-1 and Bcl-2. The overexpression of Cx43 can also increase the potency of paclitaxel by direct binding to β-tubulin [121]. Previously, it was documented that the phosphorylation of Cx43 by PKC leads to a decrease in the expression of Cx43 and that this effect makes cells of ovarian cancer more chemosensitive (paclitaxel and cisplatin have been taken into consideration) [122].…”

Molecular mechanisms of resveratrol as chemo and radiosensitizer in cancer

“…Since the antitumor agent must reach the cancer cell in an adequate concentration to exert its effect, drug uptake or release alterations could also be responsible for the acquisition of chemoresistance (Huang and Sadée, 2006). Transport proteins, also called ATP-dependent multidrug transporters (ABCs), associated with chemoresistance are multidrug resistance proteins (MDR1; P-glycoprotein [P-gp]; MRP1; ABCB1; ABCC1) (Leonard et al, 2003;Crouthamel et al, 2006;Pérez-Gutiérrez et al, 2007), the multidrug resistance-associated protein (MRP1) (Hong et al, 2019), the protein related to lung resistance (LRP) (Schneider et al, 2001;Wang, 2011) and breast cancer resistance protein (BRCP) (Fu et al, 2020). MDR proteins are ATP-binding proteins that regulate P-gp, which are responsible for removing drugs from cells using ATP hydrolysis (Yang et al, 2014).…”