Tubulin-binding anticancer polysulfides induce cell death via mitotic arrest and autophagic interference in colorectal cancer

Abstract

Polysulfanes show chemopreventive effects against gastrointestinal tumors. We identified diallyl tetrasulfide and its derivative, dibenzyl tetrasulfide (DBTTS), to be mitotic inhibitors and apoptosis inducers. Here, we translate their application in colorectal cancer (CRC). MALDI-TOF-MS analysis identified both compounds as reversible tubulin binders, validated by in cellulo α-tubulin degradation. BRAF(V600E)-mutated HT-29 cells were resistant to DBTTS, as evidenced by mitotic arrest for 48 h prior to apoptosis induction compared to KRAS(G12V)-mutated SW480/620 cells, which committed to death earlier. The prolonged mitotic block correlated with autophagy impairment and p62 protein accumulation in HT-29 but not in SW480/620 cells, whereas siRNA-mediated p62 inhibition sensitized HT-29 cells to death. In silico analysis with 484 colorectal cancer patients associated higher p62 expression and reduced autophagic flux with greater overall survival. Accordingly, we hypothesized that DBTTS targets CRC survival/death through autophagy interference in cell types with differential autophagic capacities. We confirmed the therapeutic potential of DBTTS by the inhibition of spheroid and colony formation capacities in CRC cells, as well as in HT-29 zebrafish xenografts in vivo.

Keywords: Autophagic flux; Cell death; Diallyl sulfide; Mitotic arrest; Zebrafish xenografts.