Exploring the interaction of Peloruside-A with drug resistant αβII and αβIII tubulin isotypes in human ovarian carcinoma using a molecular modeling approach.

Microtubules (MTs) play an essential role in mitosis; hence they are identified as potential targets to design novel anti-mitotic agents. MT's are composed of α/β-tubulin isotypes that are associated with differential drug-resistant effects against MT-targeting agents. Peloruside-A (PLA) is a potent anti-mitotic agent showing excellent activity against taxol-resistant carcinoma. PLA alters MT dynamics by binding to the 'non-taxoid' site of β-tubulin. The abundance of βII and βIII tubulin isotypes in human ovarian carcinoma affects the efficacy of PLA. Nevertheless, the mechanism of PLA resistance due to βII and βIII tubulin isotype is not well understood. Therefore, we investigated the interactions of PLA with αβIIa, αβIIb, and αβIII tubulin isotypes which are predominantly expressed in the human ovarian carcinoma, using a molecular modeling approach. A sequence analysis study shows that the βIII isotype has seven residue variations at the 'non-taxoid' site compared to the βIIa and βIIb isotypes. Molecular docking and molecular dynamics simulation revealed that residue variation at the 'non-taxoid' site of βIII isotype affect PLA binding. Furthermore, binding energy calculations showed that αβIIa has the highest binding towards PLA, whereas αβIIb and αβIII isotypes shows weaker associations with PLA. Our computational study provides valuable structural and energetic information to increase understanding into the origin of PLA resistance in human ovarian carcinoma and could be helpful to develop potential PLA analogs against specific β-tubulin isotypes expressed in cancer cells.Communicated by Ramaswamy H. Sarma.