Defects in the Fanconi Anemia Pathway in Head and Neck Cancer Cells Stimulate Tumor Cell Invasion through DNA-PK and Rac1 Signaling

PURPOSE: Head and neck squamous cell carcinoma (HNSCC) remains a devastating disease, and Fanconi anemia (FA) gene mutations and transcriptional repression are common. Invasive tumor behavior is associated with poor outcome, but relevant pathways triggering invasion are poorly understood. There is a significant need to improve our understanding of genetic pathways and molecular mechanisms driving advanced tumor phenotypes, to develop tailored therapies. Here we sought to investigate the phenotypic and molecular consequences of FA pathway loss in HNSCC cells. EXPERIMENTAL DESIGN: Using sporadic HNSCC cell lines with and without FA gene knockdown, we sought to characterize the phenotypic and molecular consequences of FA deficiency. FA pathway inactivation was confirmed by the detection of classic hallmarks of FA following exposure to DNA cross-linkers. Cells were subjected to RNA sequencing with qRT-PCR validation, followed by cellular adhesion and invasion assays in the presence and absence of DNA-dependent protein kinase (DNA-PK) and Rac1 inhibitors. RESULTS: We demonstrate that FA loss in HNSCC cells leads to cytoskeletal reorganization and invasive tumor cell behavior in the absence of proliferative gains. We further demonstrate that cellular invasion following FA loss is mediated, at least in part, through NHEJ-associated DNA-PK and downstream Rac1 GTPase activity. CONCLUSIONS: These findings demonstrate that FA loss stimulates HNSCC cell motility and invasion, and implicate a targetable DNA-PK/Rac1 signaling axis in advanced tumor phenotypes

Human Papillomavirus Oral- and Sero- Positivity in Fanconi Anemia

High-risk human papillomavirus (HPV) is prevalent and known to cause 5% of all cancers worldwide. The rare, cancer prone Fanconi anemia (FA) population is characterized by a predisposition to both head and neck squamous cell carcinomas and gynecological cancers, but the role of HPV in these cancers remains unclear. Prompted by a patient-family advocacy organization, oral HPV and HPV serological studies were simultaneously undertaken. Oral DNA samples from 201 individuals with FA, 303 unaffected family members, and 107 unrelated controls were tested for 37 HPV types. Serum samples from 115 individuals with FA and 55 unrelated controls were tested for antibodies against 9 HPV types. Oral HPV prevalence was higher for individuals with FA (20%) versus their parents (13%; p = 0.07), siblings (8%, p = 0.01), and unrelated controls (6%, p ≤ 0.001). A FA diagnosis increased HPV positivity 4.84-fold (95% CI: 1.96-11.93) in adjusted models compared to unrelated controls. Common risk factors associated with HPV in the general population did not predict oral positivity in FA, unlike unrelated controls. Seropositivity and anti-HPV titers did not significantly differ in FA versus unrelated controls regardless of HPV vaccination status. We conclude that individuals with FA are uniquely susceptible to oral HPV independent of conventional risk factors

Single cell transcriptomic analysis of HPV16-infected epithelium identifies a keratinocyte subpopulation implicated in cancer

The role of keratinocyte subpopulations in the different phases of the viral cycle during HPV16 infection remains to be characterised. Here, single cell RNA sequencing of HPV16 infected and uninfected organoids identifies 12 distinct keratinocyte populations including an HPV-reprogrammed keratinocyte subpopulation that is linked to cancer