Abstract People living with HIV (PWH) have an increased incidence of cancers and worse outcomes than those not infected with HIV. People at the age of 50 or older also have increased rates to acquire HIV infection. Individuals living with chronical HIV infection exhibit many clinical characteristics of aging. Moreover, PWH on combined antiretroviral therapy (ART) often have a degree of immunologic impairment and chronic immune activation. To improve health of older individuals living with HIV, we must better understand the interface between aging, HIV infection, and HIV-associated cancers. The goal of this P30 supplement project is to address these questions. N6-methyladenosine (m6A) is the most abundant internal RNA modification and plays an important role in cellular RNA fate and HIV infection and immunity. Dysregulation of m6A modification is frequently identified in various cancer types, which can serve as diagnostic, prognostic and/or predictive biomarkers. We and others found that HIV-1 in vitro infection induces a significant increase in m6A modification of cellular RNA. However, whether HIV- associated cancers affect m6A levels and profiles of cellular genes in aging PWH remain unknown. Importantly, m6A modification affects type I interferons (IFN-I) and interferon-responsive genes in HIV infection and cancers. IFN-I-responsive gene expression is often dysregulated in many cancer patients. However, it is unknown whether HIV-associated cancers can alter IFN-I-responsive gene expression in immune cells from aging PWH. We hypothesize that HIV-associated cancers increase RNA m6A levels, alter m6A-modified gene profiles, and dysregulate the mRNA expression of IFN-I-responsive genes in peripheral blood monocytic cells (PBMCs) from PWH at the age of 50 or older. To test this hypothesis and to explore the underlying mechanisms, we designed two specific aims in two years: Aim 1. To determine RNA m6A levels and m6A-modified gene profiles in PBMCs of PWH with or without HIV-associated cancers. Aim 2. To measure mRNA levels of 84 IFN-I-responsive genes in PBMCs of PWH with or without HIV-associated cancers. Overall Impact: Our proposed study will help define how m6A modification regulates cellular gene expression and innate immunity during HIV-1 infection and cancer development in aging PWH. These basic and mechanistic studies can lay the foundation for developing a better therapy approach for cancer treatment among aging PWH.