Lysine-specific demethylase 1 controls key OSCC preneoplasia inducer STAT3 through CDK7 phosphorylation during oncogenic progression and immunosuppression [Feline]

Oral Squamous Cell Carcinoma (OSCC) is a type of cancer that arises from preneoplastic precursors, which undergo genetic and epigenetic modifications. Lysine-specific demethylase 1 (LSD1) is a key OSCC promoter. LSD1 knockout or pharmacological inhibition in mouse OSCC reversed OSCC preneoplasia in our study. LSD1 inhibition attenuated the cell cycle, immunosuppression and promoted the infiltration of CD45+, TCRß+, CD4+, and CD8+ cells. Next, we tested the clinical candidate LSD1 inhibitor (Seclidemstat) in feline clinically spontaneous natural OSCC and found that it was safe and attenuated the STAT3 network. Mechanistic studies have shown that LSD1 reprograms preneoplasia to promote STAT3 signaling, cell cycle mediator CDK7, and immunosuppressive CTLA4 to OSCC progression. Interestingly, we found that the LSD1 inhibitor (SP2509) attenuated cyclin-dependent kinase 7 (CDK7) phosphorylation at T170 and eukaryotic initiation factor 4 B (Eif4B) phosphorylation at S422. We identified a new mechanism in OSCC preneoplasia that LSD1 promotes STAT3 mediated by CDK7 phosphorylation, leading to overall changes in the tumor microenvironment, leading to immunosuppression and progression to OSCC, which could have applications for understanding the mechanism as well as design strategies to control the progression of preneoplasia to OSCC. Total 1 feline patient with OSCC was recruited for this study. Tongue biopsies were collected before and after SP2577 treatment and subjected for RNA sequencing (n=3/condition).