Research Projects

Project Summary Rationale and background: High risk papillomavirus (HPV) types, notably HPV16 and HPV18 are leading causes of cervical cancer and other epithelial cancers. HPV infection is often described as a “hidden epidemic” because of its asymptomatic and self-limiting nature that gradually progresses into malignancy. Despite extensive studies, the complete oncogenic mechanisms of HPV remain unclear. HPV is known to hijack host cell regulatory pathways to create a favorable environment for its replication and persistence. Identifying key host targets of HPV is a critical area of research in understanding and combating HPV driven cancers. HPV oncoproteins E6 and E7 drive carcinogenesis by degrading p53 and inactivating Rb, disrupting cell cycle control. Beyond these canonical pathways, our lab has uncovered a novel mechanism where HPV16E6 targets Cdh1, a key Anaphase Promoting Complex/Cyclosome (APC/C) coactivator. Cdh1 is an established regulator of cell cycle, genomic stability, and tumor suppression. E6 mediated loss of Cdh1 can cause aberrant substrate accumulation and neoplastic transformation. Our preliminary findings reveal that HPV16E6 reduces Cdh1 levels and promotes its degradation via the ubiquitin proteasome pathway (UPS). This novel E6-Cdh1 axis represents an underexplored but critical mechanism of HPV driven oncogenesis and provides a compelling rationale to explore it as a therapeutic target. HYPOTHESIS: We hypothesize that E6 promotes tumorigenesis by targeting Cdh1 leading to APC/C inactivation and accumulation of oncogenic substrates causing uncontrolled cell proliferation. Restoring Cdh1 function either genetically or pharmacologically, may reactivate APC/C, reverse oncogenic effects and suppress tumor growth, offering a novel therapeutic approach for HP positive cancers. Objectives: 1. Characterization of the HPV16E6-Cdh1 Interaction and its Impact on Cdh1 Turnover: This aims to map the E6-Cdh1 interaction domain and identify degradation resistant Cdh1 mutants. Using Western blotting, Microscopy, Ubiquitination, Cycloheximide chase, and MG132 assays, we will assess localization of proteins and Cdh1 stability in the presence of E6. CRISPR-Cas9-mediated E6 knockout in HPV positive cells will further validate E6 dependent Cdh1 destabilization. 2. Assessment of the Functional Consequences of Cdh1 Destabilization on Cell cycle and Proliferation: This objective will assess how E6 induced Cdh1 degradation affect cell cycle and growth. FACS, BrDU, Ki-67, colony formation, Western and qRT-PCR are key techniques. Rescue with degradation resistant Cdh1 will test if restoring its function reverses oncogenic effects. 3. Identification and Evaluation of Therapeutic strategies to Restore Cdh1 function in HPV Positive Cancer: It will identify compounds that restore Cdh1 function by preventing its degradation or E6-Cdh1 interaction. A fluorescence based HTS platform using GFP- Cdh1 reporter cells will be developed. Selected compound libraries will be screened, and promising hits will be validated through Western, ubiquitination analysis, and restoration of Cdh1 activity. 4. Transcriptomic and Proteomic profiling of E6-Cdh1 axis in vivo: Using HPV16E6 expressing Xenograft models, we will assess tumor response to Cdh1 restoration (genetic or pharmacological). Tumor growth, histopathology and IHC for proliferation markers and APC/C substrates will be analyzed. Transcriptomic and proteomic profiling of tumor tissue will identify downstream signaling alterations and validate potential therapeutic targets. Significance and Expected impact: This project uncovers the novel mechanism for HPV16E6 mediated tumorigenesis via Cdh1 degradation and APC/C impairment, addressing a key gap in HPV research. It is expected to offer mechanistic insights and translational potential. The work could establish the E6-Cdh1 axis as a promising target for HPV-associated cancers that are unresponsive to existing treatments.