Goutham, S. | Search bioRxiv

bioRxiv2024

Collective amoeboid dynamics drives colonization of drug-resistant ovarian cancer cells

Epithelial ovarian cancer (EOC) is characterized by resistance to platinum-based therapy, resulting in rapid progression and poor survival. Here, we ask whether drug resistance and invasiveness coevolve to drive metastasis. Selection experiments involving pulsed carboplatin exposure established isogenic chemoresistant variants of lines, which typify high-grade serous ovarian carcinoma (HGSOC), the most aggressive type of EOC. Time-lapse imaging showed enhanced migration of resistant single cells and their collectives. Resistant cell spheroids spread faster on Collagen I substrata than sensitive controls. The resistant OVCAR-3 transcriptome was ontologically enriched for migration and showed overlap with previously reported markers of resistance in EOC patients and other evolved lines. Gene set enrichment predicted transition between epithelial, mesenchymal, and amoeboid states is higher in resistance compared to control lines. Lower matrix adhesion, weak focal adhesion, and highly deformable and translatory dynamics of cell collectives indicated that resistant cancer cells displayed a unique collective amoeboid-like migration. When injected intraperitoneally into immunodeficient mice, resistant cells colonized to a greater extent on parietal mucosae. Ex vivo, suspended resistant cells formed moruloids associated with quicker peritoneal adhesion, clearing human coelomic mesothelial monolayers with higher efficiency. Knockdown in resistant OVCAR-3 cells of two upregulated proteins, E-cadherin and LGALS3BP, had distinct consequences. E-cadherin knockdown partially restored sensitivity to carboplatin but did not affect invasion. In contrast, silencing LGALS3BP decreased invasion but not resistance. Our results suggest that drug resistance and invasiveness could coevolve through the upregulation of distinct trait drivers in EOC.

cancer biology↗

bioRxiv2018

Mutually exclusive locales for N-linked glycans and disorder in glycoproteins

Several post-translational modifications of proteins lie within regions of disorder, stretches of amino acid residues that exhibit a dynamic tertiary structure and resist crystallization. Such localization has been proposed to expand the binding versatility of the disordered regions, and hence, the repertoire of interacting partners for the proteins. However, investigating a dataset of 500 human N-linked glycoproteins, we observed that the sites of N-linked glycosylations, or N-glycosites, lay predominantly within the regions of predicted order rather than their unstructured counterparts. This mutual exclusivity between disordered stretches and N-glycosites could not be reconciled merely through asymmetry in distribution of asparagines, serines or threonines residues, which comprise the minimum-required signature for conjugation by N-linked glycans, but rather by a contextual enrichment of these residues next to each other within the ordered portions. In fact, N-glycosite neighborhoods and disordered stretches showed distinct sets of enriched residues suggesting their individualized roles in protein phenotype. N-glycosite neighborhood residues also showed higher phylogenetic conservation than disordered stretches within amniote orthologs of glycoproteins. However, a universal search for residue-combinations that are putatively domain-constitutive ranked the disordered regions higher than the N-glycosite neighborhoods. We propose that amino acid residue-combinations bias the permissivity for N-glycoconjugation within ordered regions, so as to balance the tradeoff between the evolution of protein stability, and function, contributed by the N-linked glycans and disordered regions respectively.

bioinformatics↗