Fig 2: Siva-1 interacted with PCBP1. (A) Library quality test showed that the homogenized secondary yeast two-hybrid cDNA library capacity was 9.56 × 106 CFU. (B, C) Yeast two-hybrid assays were performed to search for proteins that interacted with Siva-1. The bait vector with truncated Siva-1 gene was constructed for screening a human gastric cancer yeast two-hybrid cDNA library, and PCBP1 and UXT were identified. Interactions were confirmed based on co-transformants that can grow on histidine-deficient (-His) plates and exhibit ß-galactosidase activity. (D) co-IP of Siva-1 with the PCBP1 protein. (E) co-IP to validated Siva-1 and UXT protein interaction in 293 T cells (*p < 0.05; NC: negative control; PC: positive control; IP: immunoprecipitation; IB: immunoblotting; SD: synthetic dropout medium).

Fig 3: The effect on cell colony forming efficiency, the migratory rate, and invasion rate in MKN-28/VCR after Siva-1 was inhibited. (A, B) Proliferation rate of MKN-28/VCR after Siva-1 was inhibited, analyzed by cell colony assay. (C, D) Migratory rate of MKN-28/VCR after Siva-1 was inhibited, analyzed in wound healing assay. (E, F) Invasion rate of MKN-28/VCR after Siva-1 was inhibited, analyzed by transwell assay (*p < 0.05).

Fig 4: The effect on cell pump rate of doxorubicin, cell cycle, and apoptotic rate in MKN-28/VCR after Siva-1 was inhibited. (A, B) Pump rate of doxorubicin in MKN-28/VCR after Siva-1 was inhibited, analyzed by flow cytometry. (C, D) Cell cycle in MKN-28/VCR cells after Siva-1 was inhibited, analyzed by flow cytometry. (E, F) Apoptotic rate in MKN-28/VCR cells, analyzed by flow cytometry (*p < 0.05).

Fig 5: Siva-1 regulate PCBP1/Akt/NF-?B signaling pathway expression. (A, B) Relative expression levels of Siva-1 and its density quantification result. (C) Relative expression of Siva-1, PCBP1, Akt, NF-?B, MRP1, and MDR1 mRNA in MKN-28/VCR-shRNA-Siva-1 cells, MKN-28/VCR-shRNA-NC cells, and MKN-28/VCR cells. (D, E) Relative protein expression levels of PCBP1, Akt, NF-?B, MRP1, and MDR1 and their density quantification results. (F, G) Relative protein expression levels of Akt, NF-?B, MRP1, and MDR1 and their density quantification results (*p < 0.05; 1: MKN-28/VCR-shRNA-Siva-1; 2: MKN-28/VCR-shRNA-NC; 3: MKN-28/VCR; 4: MKN-28/VCR with Akt inhibitor).