Neat-1: Culprit lnRNA tying PIG-C, MSLN, CD80 in TNBC

Abstract

Background: Continuous effort unraveled GPI pathway that anchors cell surface proteins mediating tumor microenvironment interactions. GPI axis is initiated in breast cancer upon PIG-C elevation which induces MSLN surface expession. MSLN is antiapoptotic GPI-AP, whose immune therapies yielded tremendous results. CD80 is a unique immunomodulator that binds to CD28, CTLA4 and PDL1. Recombinant GPICD80 is evaluated as tumor vaccine. RNAi is a promising tool for immuno-targeted therapy as crucial immuno modulators are blocked. Our aim is to investigate impact of nc-RNAs on MSLN, PIG-C and CD80 for the first time. Methods: miR-2355, miR-455 and NEAT-1 targeted MSLN, PIG-C and CD80 by bioinformatic analysis. MSLN/CD80 plasmids were transfected in MDA-MB-231 cells, then treated with synthetic nc-RNAs. Surface CD80 and MSLN were assessed by flow cytometry. Gene mRNA level was tested by q-PCR. Results: PIG-C Silencing, NEAT-1 and miR-2355 elevation, plus NEAT-1/miR-2355 combination droped PIG-C mRNA level signtificantly (p<0.0001 each) compared to untreated cells and miR-2355 inhibitor (P<0.0001) miR-2355 elevation significantly droped MSLN mRNA level compared to untreated cells (P<0.0001) Conversely, miR- 2355 inhibitor, NEAT-1 mimic and NEAT-1/miR-2355 combination significantly increased MSLN expression level (P<0.0001 each). PIG-C siRNA did not have significant effect on MSLN mRNA level PIG-C siRNA and miR-2355 mimic significantly droped MSLN surface level MFI compared to mock (P<0.0001 each) but miR-2355 inhibitor significantly increased MSLN MFI (P<0.0001) NEAT-1 mimic and NEAT- 1/miR-2355 combination did not have significant effect on MSLN MFI. miR-455 mimic signifincantly droped both surface CD80 MFI and CD80 mRNA level compared to mock (P<0.0001) Contrastingly, miR-455 inhibitor significantly increased both CD80 MFI and CD80 mRNA level compare to mock (P<0.0001) NEAT-1 mimic and NEAT-1/miR-455 combination did not show significant effect on CD80 MFI or CD80 mRNA level. Conclusions: To sum up, our study sheds light on new targets for breast cancer immunotherapy. NEAT-1 is dominant promising sponge for several mi-RNAs which potientiates its role in governing many immunomoduolatory pathways. Our study paves the way for future investigations on the role of NEAT-1 in immuno-targeted therapy.