Chronic infections are associated with increased cancer risk. In the case of hepatocellular carcinoma (HCC), a liver cancer, 40-80% of the cases are attributable to Hepatitis C virus (HCV) infections . In the U.S., HCV-infected Hispanics have a significantly higher risk of developing cirrhosis and HCC compared to other racial groups [2, 3]. Direct acting antivirals (DAAs) for HCV infection are promising, however treatment failure can occur and it is not known whether the DAAs prevent progression to HCC. A critical step is to establish basic research to identify potential biomarkers present during HCV infection that can be used to predict HCC progression as well as to identify immunotherapies that can prevent cancer progression. Two immune cell subsets that may be involved in HCC progression include T exhausted (TEX) cells [4-11] and myeloid-derived suppressor cells (MDSC) [12-21] whose levels are elevated in cancers and persistent infections, and correlate with poor prognoses for cancers [12, 22]. We hypothesize that elevated levels of TEX and MDSC in persistent HCV infections promote development of HCC. We will determine the frequency of TEX and MDSC populations in HCV-infected individuals with and without HCC (Specific Aim 1). TEX have a distinct epigenetic profile during multiple persistent infections including HCV infections [9, 23]. Thus, we hypothesize that epigenetic modifications in the TEX population contribute to the development of HCV-induced HCC. We will examine epigenetic profiles in the TEX cell subset within HCV-infected individuals with and without HCC to identify potential therapeutic targets (Specific Aim 2).
Specific Aim 1. Determine whether there are increased levels of TEX and MDSC in HCV-infected individuals in contrast to HCV-infected individuals with HCC. We will quantify the levels of TEX and MDSC in Puerto Rican and Cuban individuals that are HCV infected without HCC (HCV+, HCC-); HCV infected with HCC (HCV+, HCC+); HCV-negative with HCC (HCV-, HCC+); and healthy (HCV-, HCC-). We will use cell surface staining and flow cytometry to quantify TEX and MDSC populations in the blood and in the tumor microenvironment (TME) by immunohistochemistry.
Specific Aim 2. Identify epigenetic changes in TEX in HCV-infected individuals, with and without HCC. We will perform epigenetic analyses of TEX populations. We will first isolate pure TEX populations by flow cytometry sorting and perform epigenetic mapping by the assay for transposase accessible chromatin sequencing (ATAC-seq).