Rupesh Dash

Background Docetaxel is the most common chemotherapy regimen for several neoplasms, including advanced OSCC (Oral Squamous Cell Carcinoma). Unfortunately, chemoresistance leads to relapse and adverse disease outcomes. Methods We performed CRISPR-based kinome screening to identify potential players of Docetaxel resistance. Immunohistochemistry was performed to examine the expression profile of the target gene across tumour tissues. Global transcriptome analysis was performed to determine the molecular mechanism underlying Docetaxel resistance. NEK9 kinase assay was performed to identify a putative kinase inhibitor. Results Upon conducting CRISPR-based kinome screening, Never In Mitosis Gene-A Related Kinase-9 (NEK9) was identified as a major player of Docetaxel resistance in OSCC, prostate, and pancreatic cancer lines. NEK9 expression was found to be upregulated in chemotherapy non-responder OSCC patients as compared to responders. NEK9 ablation restores Docetaxel-induced cell death in chemoresistant cells. Mechanistically, we found that NEK9 deletion upregulates Transducin-like enhancer protein 3 (TLE3), which in turn represses Wnt signalling. Fostamatinib was identified as a potent NEK9 inhibitor that overcomes Docetaxel resistance. Conclusions Our study demonstrated that NEK9 plays an important role in Docetaxel resistance. The novel combination of NEK9 inhibitor Fostamatinib and Docetaxel needs further clinical investigation in advanced OSCC.

Docetaxel alone or in combination with other drugs is the most common chemotherapy regimen for several neoplasms including advanced OSCC. Unfortunately, chemoresistance leads to relapse and continued tumor growth. It is therefore important to explore the causative factors for docetaxel resistance. In this study, we performed a CRISPR-based kinome screening that identified Never In Mitosis Gene-A Related Kinase-9 (NEK9) as a major player of docetaxel resistance in OSCC, prostate, and pancreatic cancer lines. NEK9 expression was upregulated in tumor samples of chemotherapy non-responders compared to responder OSCC patients. Our validation data suggests selectively knocking out NEK9 sensitizes cancer cells to docetaxel. Mechanistically, we found that ablation of NEK9 induces DNA damage, activating ERK(p-T202/Y204) that leads to Gasdermin-E mediated Cancer Cell pyroptosis. The in-vitro kinase activity assay identified fostamatinib as a potent inhibitor of NEK9. The xenograft data suggest that fostamatinib restores docetaxel sensitivity and facilitates a significant reduction of tumor burden. Overall, our data suggests a novel combination of fostamatinib and docetaxel needs further clinical investigation in advanced OSCC.

Chemoresistance is one of the major factors for treatment failure in OSCC. Reprogramming chemoresistance cells to undergo drug induced apoptotic cell death is a feasible approach to overcome drug resistance. Cyanobacteria is considered important sources of lead compounds for the development of drugs for treating cancer chemoresistance. This study deals with the role of Tolypothrix Dichloromethane Ethyl acetate fraction (TDEF) inducing apoptosis in cisplatin resistance H357 cell (H357cisR) and the underlying mechanisms sensitizing the chemoresistance. TDEF showing effective activity against H357cisR with IC₅₀-14.13±1.18 µg mL^-1, inhibits proliferation and migration. Proteome apoptosis arrays were found to stimulate phosphorylation of p53, activation of proapoptotic proteins including BAX and cytochrome C (CYCS), caspase-3/9 (CASP3/9), suppression of anti-apoptotic proteins like Bcl2, survivin and increased expression of the cell cycle checkpoint protein p21, p27. TDEF induced apoptosis with cell death-transducing signals, that regulate the Matrix metalloproteinases (MMPs) by down-regulation of Bcl2 and up-regulation of Bax, triggering the cytochrome c release from mitochondria to cytosol thus triggered the activation of caspases-9 to activate downstream executioner caspase-3/7 required for apoptotic changes. The mechanistic pathway of apoptotic cell death in H357cisR was done through inhibiting β-catenin through GSK3β in turn activated by AKT. The phosphorylated β-catenin leads to proteasome degradation and unable to translocation to nucleus thereby activating c-Myc, survivin, Cyclin D and upregulate p21 expression which lead to cell cycle arrest in G₀/G₁ phase.