Oncogenic role and potential regulatory mechanism of fatty acid binding protein 5 based on a pan-cancer analysis.

As one member of fatty acid binding proteins (FABPs), FABP5 makes a contribution in the occurrence and development of several tumor types, but existing analysis about FABP5 and FABP5-related molecular mechanism remains limited. Meanwhile, some tumor patients showed limited response rates to current immunotherapy, and more potential targets need to be explored for the improvement of immunotherapy. In this study, we made a pan-cancer analysis of FABP5 based on the clinical data from The Cancer Genome Atlas database for the first time. FABP5 overexpression was observed in many tumor types, and was statistically associated with poor prognosis of several tumor types. Additionally, we further explored FABP5-related miRNAs and corresponding lncRNAs. Then, miR-577-FABP5 regulatory network in kidney renal clear cell carcinoma as well as CD27-AS1/GUSBP11/SNHG16/TTC28-AS1-miR-22-3p-FABP5 competing endogenous RNA regulatory network in liver hepatocellular carcinoma were constructed. Meanwhile, Western Blot and reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) analysis were used to verify miR-22-3p-FABP5 relationship in LIHC cell lines. Moreover, the potential relationships of FABP5 with immune infiltration and six immune checkpoints (CD274, CTLA4, HAVCR2, LAG3, PDCD1 and TIGIT) were discovered. Our work not only deepens the understanding of FABP5's functions in multiple tumors and supplements existing FABP5-related mechanisms, but also provides more possibilities for immunotherapy.