PX-12

The hypoxic tumor microenvironment (TME) in oral squamous cell carcinoma (OSCC) is primarily regulated by hypoxia-inducible factor-1 alpha (HIF-1α), impacting histone acetylation and methylation, which contribute to drug resistance. Vorinostat, a histone deacetylase inhibitor (HDACi), de-stabilizes HIF-1α, while PX-12, a thioredoxin-1 (Trx-1) inhibitor, prevents HIF-1α accumulation. Combining HDACi with a Trx-1 inhibitor may enhance efficacy and reduce resistance by increasing reactive oxygen species (ROS) in cancer cells. This study examines how PX-12 influences vorinostat-induced histone modifications under hypoxia in the OSCC cell line CAL 27 using mass spectrometry.

The OSCC cell line CAL 27 was used to assess histone post-translational modifications induced by PX-12 and Vorinostat under hypoxic conditions through mass spectrometry.

The proteomic analysis (ProteomeXchange identifier PXD053244) revealed several crucial histone marks, such as H3K4me1, H3K9ac, H3K9me, H3K14ac, H3K27me, H3K36me, H4K12Ac, and H4K16ac. Along with site-specific histone modifications, exposure of cells to vorinostat and PX-12 alone or in combination affects the global acetylation and methylation levels under hypoxia.

Mass spectrometry-based proteomics highlighted the impact of vorinostat and PX-12 on histone acetylation and methylation, offering valuable insights into the epigenetic mechanisms in OSCC and paving a way for epigenetic-based oral cancer therapeutics.

Aims: The nuclear factor erythroid 2-related factor 2-Kelch-like ECH-associated protein 1 (NRF2-KEAP1) pathway plays an important role in the cellular response to oxidative stress but may also contribute to metabolic changes and drug resistance in cancer. However, despite its pervasiveness and important role, most of nuclear factor erythroid 2-related factor 2 (NRF2) target genes are defined in context-specific experiments and analysis, making it difficult to translate from one situation to another. Our study investigates whether a core NRF2 gene signature can be derived and used to represent NRF2 activation in various contexts, allowing better reproducibility and understanding of NRF2. Results: We define a core set of 14 upregulated NRF2 target genes from 7 RNA-sequencing datasets that we generated and analyzed. This NRF2 gene signature was validated using analyses of published datasets and gene sets. An NRF2 activity score based on expression of these core target genes correlates with resistance to drugs such as PX-12 and necrosulfonamide but not to paclitaxel or bardoxolone methyl. We validated these findings in our Kelch-like ECH-associated protein 1 (KEAP1) knockout cancer cell lines. Finally, our NRF2 score is prognostic for cancer survival and validated in additional independent cohorts for lung adenocarcinoma and also novel cancer types not associated with NRF2-KEAP1 mutations such as clear cell renal carcinoma, hepatocellular carcinoma, and acute myeloid leukemia. Innovation and Conclusions: These analyses define a core NRF2 gene signature that is robust, versatile, and useful for evaluating NRF2 activity and for predicting drug resistance and cancer prognosis. Using this gene signature, we uncovered novel selective drug resistance and cancer prognosis associated with NRF2 activation. Antioxid. Redox Signal. 41, 1031-1050.