Interaction between CDC6 and Tmod3 accelerates resistance to paclitaxel through focal adhesion assembly.

The widespread clinical application of paclitaxel (PTX) in cancer treatment has been significantly limited by the emergence of drug resistance and the presence of drug-tolerant persister cells. To systematically identify key regulators of this resistance, we conducted a genome-wide CRISPR/Cas9 knockout screen, which revealed that cell division cycle 6 (CDC6) is a critical determinant of cell adhesion-mediated PTX resistance. Furthermore, our results illustrate that CDC6, an essential DNA replication licensing factor, functions through a pathway distinct from previously well-characterized resistance mechanisms. Genetic depletion of CDC6 considerably sensitizes cells, markedly increasing PTX-induced cell death. In addition to its established role in chromosome stability, CDC6 physically interacts with tropomodulin-3 (Tmod3) in the cytoplasmic compartment. This interaction enhances CDC6 protein stability and drives drug resistance phenotypes through the regulation of actin cytoskeleton remodeling and facilitating focal adhesion assembly. In addition, combination treatment with PTX and actin filament inhibitors synergistically enhanced the antitumor efficacy both in vitro and in vivo. Overall, our studies elucidate the mechanisms through which CDC6 functions as a key regulator of PTX resistance and provide a potential therapeutic strategy to increase PTX efficacy through the modulation of the cytoskeletal-adhesion axis.