Cystathionine Beta-Synthase Promotes Anoikis Resistance and Transcoelomic Metastasis in Ovarian Cancer via the SP1-ITGB1 axis.

Anoikis resistance is crucial for ovarian cancer (OvCa) transcoelomic metastasis, during which exfoliated OvCa cells survive as spheroids before invading the omentum. Here, we demonstrate that cystathionine β-synthase (CBS), an H2S-producing transsulfuration pathway enzyme, is a key determining factor of OvCa spheroidal viability and metastatic potential. Analysis of publicly available patient datasets, as well as an in-house tissue microarray revealed that high CBS expression positively correlates with poor progression-free survival and clinically observed peritoneal/omental metastasis. Integrated functional and proteomic analyses indicated that CBS silencing induces apoptosis in 2D monolayers. Consistent with this, CBS silencing in spheroids caused apoptosis along and disrupted spheroid architecture. Mechanistically, this phenotype was associated with downregulation of oncogenic stemness and epithelial-mesenchymal transition. Further, through proteomic and bioinformatic analyses, we identified ITGB1 to be the hub protein in OvCa spheroidogenesis. Interestingly, knockdown of CBS led to abrogation of the ITGB1-mediated downstream pathway. Moreover, by proteomic and network analyses, we identified SP1 as a key transcriptional regulator of CBS-induced pro-spheroidal transcriptional programs of stemness and invasiveness. Stabilization of SP1 through persulfidation by H2S supplementation restored spheroidal viability and underlying protein signaling. Further, our results reveal that loss of CBS through ITGB1 repression disrupts spheroid architecture, leading to reduced metastatic docking on the murine omental surface