Evaluating STING Agonist Impact on Kaposi’s Sarcoma-Associated Virus-related Cancers

Kaposi’s sarcoma-associated herpesvirus (KSHV) is an etiological agent of multiple malignancies associated with compromised immunity, such as Kaposi’s sarcoma (KS) and Primary Effusion Lymphoma (PEL). KSHV infection is lifelong with no available treatment or vaccines and poses a high risk to immunocompromised individuals. The virus is transmitted via the oral and sexual route, and has a biphasic life cycle with a short lytic replication cycle followed by long-term latency, with the expression of few genes making detection difficult. Reactivation from latency results in a cascade of viral gene expression and pathogenesis. Critical to controlling KSHV infection is the cGAS-STING DNA-sensing pathway (STING), known to activate the type I interferon response and induce cancer cell death or growth inhibition. STING exhibits both anti-viral and anti-tumor responses, showing promise as a protein of interest to study for the development of a therapeutic treatment. By examining the in vitro effectiveness of STING agonists in inhibiting KSHV oncogenesis in PEL, the study aimed to provide the foundation for a potential novel therapeutic approach. Six patient-derived PEL cell lines were treated with the STING agonist diaminobenzamidazole (diABZI) in a dose-dependent manner. Four of the PEL cell lines exhibited decreased cell growth, viability, and colony formation, while two PEL cell lines were resistant to treatment, correlating with the presence or absence of STING expression. RNA-sequencing was performed and discovered upregulation of multiple interferon-stimulated genes (ISG) in responsive cell lines. Further investigations will explore STING agonists’ inhibition of PEL oncogenesis in vitro via colony formation and in vivo using a PEL xenograft model with NSG mice. Successful completion of this project will offer insight into potential clinical treatments for targeting KSHV infection and reactivation.