Proteomic analysis of bladder cancer by iTRAQ after Bifidobacterium infantis-mediated HSV-TK/GCV suicide gene treatment

In our previous studies, we constructed the Bifidobacterium infantis thymidine kinase/nucleoside analogue ganciclovir (BI-TK/GCV) system, which was proven to have a sustainable antitumor activity in an in vivo bladder cancer rodent model. In this article, a proteomic approach of isobaric tags for relative and absolute quantification (iTRAQ) and followed by liquid chromatography-tandem mass spectrometry was used to understand the molecular mechanisms of this system. iTRAQ identified 192 downregulated and 210 upregulated proteins after treatment with BI-TK/GCV in Sprague-Dawley rats. Downregulations of proliferating cell nuclear antigen (PCNA), pyruvate kinase isozymes M2 (PKM2), hexokinase 1 (HXK-1), 6-phosphofructokinase (PFK-B), and cell surface glycoprotein (CD146) in bladder cancer after treatment were confirmed by Western blot analysis and validated by immunohistochemistry. Furthermore, the networks of cancer proliferation associated with PCNA, glycolysis associated with PKM2, HXK-1, and PFK-B, and invasion associated with CD146 were illustrated using Ingenuity Pathway Analysis. This study represents the successful application of iTRAQ technology to reveal the molecular mechanisms of BI-TK/GCV treatment system and provides the theoretical support for the effectiveness of our successful treatment system.