Whole-Transcriptome Sequencing Combined with HighDimensional Proteomic Technologies Reveals the Potential Value of miR-135b-5p as a Biomarker for Hepatocellular Carcinoma

Purpose. Hepatocellular carcinoma (HCC) is a disease with great heterogeneity and a highmortality rate. It is crucial to identify reliable biomarkers for diagnosis, prognosis, and treatment to improve clinical outcomes in patients with HCC. Alpha-fetoprotein (AFP) is not only a widely used biomarker in clinical practice but also plays a complicated role in HCC, and it has recently been considered to be related to immunotherapy. MicroRNAs (miRNAs) are regarded as key regulators and promising biomarkers of HCC. We investigated the role of an AFP-related miRNA, miR-135b-5p, in HCC progression. Methods. Identification of miR-135b-5p was performed based on a cohort of 65 HCC cases and the liver hepatocellular carcinoma cohort of The Cancer Genome Atlas (Asian people only). A combination of whole-transcriptome sequencing and high-dimensional proteomic technologies was used to study the role of miR-135b-5p in HCC. Results. Upregulation of miR-135b-5p was detected in patients with HCC with high serum AFP levels (AFP > 400 ng/ml). Elevated miR-135b-5p expression was associated with adverse prognosis. We also identified the relevance between high miR-135b-5p expression and tumor-related pathological characteristics, such as Edmondson grade and vascular invasion. We revealed tyrosine kinase nonreceptor 1 as a potential target of miR-135b-5p. Additionally, the transcriptional start site of miR-135b-5p had potential binding sites for SRY-box transcription factor 9, and the stemness properties of tumor cells were more remarkable in HCC with the upregulation of miR-135b-5p. The molecular characterization of the miR-135b-5p-high group was similar to that of the HCC subclasses containing moderately and poorly differentiated tumors. Finally, gene signatures associated with improved clinical outcomes in immune checkpoint inhibitor therapy were upregulated in the miR-135b-5p-high group. Conclusion. miR-135b-5p could be a biomarker for predicting the prognosis and antiprogrammed cell death protein 1 monotherapy response in HCC.