BackgroundAnti-PD-1/PD-L1 immunotherapeutic approaches have shown high clinical effectiveness in several malignancies. However, this was not the case among the hepatocellular carcinoma (HCC) patients. Multiple trials were initiated to improve its response rate among HCC patients. Several combinational approaches have been investigated. T-cell immune receptor with immunoglobulin and ITIM domains (TIGIT) is a novel co-inhibitory molecule holding a lot of promises in the field of immunooncology. TIGIT expression is highly correlated with PD-1 expression on immune cells. Recently, CD-155 (TIGIT ligand) was reported to be overexpressed in HCC patients and inversely correlated with the tumor grade. Long non-coding RNAs (LncRNAs) is a recent class of ncRNAs. CCAT-1, H19 and MALAT-1 are oncogenic lncRNAs in HCC. However, their immunological role has yet to be explored. The aim of this study is to investigate the potential of CCAT-1, H19 and MALAT-1 lncRNAs to modulate TIGIT/CD155 and PD-1/PD-L1 axes in HCC patients and cell lines.MethodsScreening was performed in 26 HCC patients and 14 healthy controls. Peripheral blood mononuclear cells (PBMCs) were isolated using ficol separation techniques. Huh7 cell lines were cultured and transfected using CCAT-1, H19 and MALAT-1 siRNAs using lipofection techniques. Total RNA was extracted using Trizol, reverse transcribed and quantified using q-RT-PCR. Ex-vivo model has been established by co-culturing PBMCs with Huh7 cells with an effector: target ratio 5:1. Cellular cytotoxicity was measured using LDH assay.ResultsCCAT-1, H19 and MALAT-1 were highly upregulated in tissues, PBMCs and sera of HCC patients. PD-L1 and CD-155 were upregulated in HCC tissues. PD-1 and TIGIT were highly upregulated in PBMCs of HCC patients compared to controls. Knocking down of CCAT-1, H19 and MALAT-1 in Huh7 cells resulted in a dual repression of PD-L1 and CD-155. Upon co-culturing transfected Huh-7 cells with PBMCs of HCC patients, a marked increase in PBMCs cytotoxicity was observed compared to PBMCs co-transfected with mock cells.ConclusionsCCAT-1, H19 and MALAT-1 are novel oncoimmunological lncRNAs that hold high therapeutic potential hindering HCC progression and modulate PD-1/PD-L1 and CD-155/TIGIT axes.Legal entity responsible for the studyThe authors.FundingHas not received any funding.DisclosureAll authors have declared no conflicts of interest. BackgroundAnti-PD-1/PD-L1 immunotherapeutic approaches have shown high clinical effectiveness in several malignancies. However, this was not the case among the hepatocellular carcinoma (HCC) patients. Multiple trials were initiated to improve its response rate among HCC patients. Several combinational approaches have been investigated. T-cell immune receptor with immunoglobulin and ITIM domains (TIGIT) is a novel co-inhibitory molecule holding a lot of promises in the field of immunooncology. TIGIT expression is highly correlated with PD-1 expression on immune cells. Recently, CD-155 (TIGIT ligand) was reported to be overexpressed in HCC patients and inversely correlated with the tumor grade. Long non-coding RNAs (LncRNAs) is a recent class of ncRNAs. CCAT-1, H19 and MALAT-1 are oncogenic lncRNAs in HCC. However, their immunological role has yet to be explored. The aim of this study is to investigate the potential of CCAT-1, H19 and MALAT-1 lncRNAs to modulate TIGIT/CD155 and PD-1/PD-L1 axes in HCC patients and cell lines. Anti-PD-1/PD-L1 immunotherapeutic approaches have shown high clinical effectiveness in several malignancies. However, this was not the case among the hepatocellular carcinoma (HCC) patients. Multiple trials were initiated to improve its response rate among HCC patients. Several combinational approaches have been investigated. T-cell immune receptor with immunoglobulin and ITIM domains (TIGIT) is a novel co-inhibitory molecule holding a lot of promises in the field of immunooncology. TIGIT expression is highly correlated with PD-1 expression on immune cells. Recently, CD-155 (TIGIT ligand) was reported to be overexpressed in HCC patients and inversely correlated with the tumor grade. Long non-coding RNAs (LncRNAs) is a recent class of ncRNAs. CCAT-1, H19 and MALAT-1 are oncogenic lncRNAs in HCC. However, their immunological role has yet to be explored. The aim of this study is to investigate the potential of CCAT-1, H19 and MALAT-1 lncRNAs to modulate TIGIT/CD155 and PD-1/PD-L1 axes in HCC patients and cell lines. MethodsScreening was performed in 26 HCC patients and 14 healthy controls. Peripheral blood mononuclear cells (PBMCs) were isolated using ficol separation techniques. Huh7 cell lines were cultured and transfected using CCAT-1, H19 and MALAT-1 siRNAs using lipofection techniques. Total RNA was extracted using Trizol, reverse transcribed and quantified using q-RT-PCR. Ex-vivo model has been established by co-culturing PBMCs with Huh7 cells with an effector: target ratio 5:1. Cellular cytotoxicity was measured using LDH assay. Screening was performed in 26 HCC patients and 14 healthy controls. Peripheral blood mononuclear cells (PBMCs) were isolated using ficol separation techniques. Huh7 cell lines were cultured and transfected using CCAT-1, H19 and MALAT-1 siRNAs using lipofection techniques. Total RNA was extracted using Trizol, reverse transcribed and quantified using q-RT-PCR. Ex-vivo model has been established by co-culturing PBMCs with Huh7 cells with an effector: target ratio 5:1. Cellular cytotoxicity was measured using LDH assay. ResultsCCAT-1, H19 and MALAT-1 were highly upregulated in tissues, PBMCs and sera of HCC patients. PD-L1 and CD-155 were upregulated in HCC tissues. PD-1 and TIGIT were highly upregulated in PBMCs of HCC patients compared to controls. Knocking down of CCAT-1, H19 and MALAT-1 in Huh7 cells resulted in a dual repression of PD-L1 and CD-155. Upon co-culturing transfected Huh-7 cells with PBMCs of HCC patients, a marked increase in PBMCs cytotoxicity was observed compared to PBMCs co-transfected with mock cells. CCAT-1, H19 and MALAT-1 were highly upregulated in tissues, PBMCs and sera of HCC patients. PD-L1 and CD-155 were upregulated in HCC tissues. PD-1 and TIGIT were highly upregulated in PBMCs of HCC patients compared to controls. Knocking down of CCAT-1, H19 and MALAT-1 in Huh7 cells resulted in a dual repression of PD-L1 and CD-155. Upon co-culturing transfected Huh-7 cells with PBMCs of HCC patients, a marked increase in PBMCs cytotoxicity was observed compared to PBMCs co-transfected with mock cells. ConclusionsCCAT-1, H19 and MALAT-1 are novel oncoimmunological lncRNAs that hold high therapeutic potential hindering HCC progression and modulate PD-1/PD-L1 and CD-155/TIGIT axes. CCAT-1, H19 and MALAT-1 are novel oncoimmunological lncRNAs that hold high therapeutic potential hindering HCC progression and modulate PD-1/PD-L1 and CD-155/TIGIT axes.