Correlation between KAT6A and PD-L1 expression and role of KAT6A in colorectal cancer.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are effective cancer treatments; however, a significant proportion of colorectal cancer (CRC) patients exhibit limited responses to ICI therapy. KAT6A has been strongly associated with cancer initiation and progression. AIM: To examine the role of KAT6A in CRC progression and immune evasion. METHODS: The functional role of KAT6A was evaluated through genetic knockdown, pharmacological inhibition (WM-3835), and CRISPR/dCas9-mediated epigenetic editing in CRC cells. T cell-mediated apoptosis was assessed using co-culture models, and H3K23pr was measured via chromatin immunoprecipitation assays. PD-L1 expression at mRNA and protein levels was analyzed under KAT6A knockdown conditions. RESULTS: KAT6A suppression reduced CRC cell proliferation, invasion, and migration. Pharmacological or epigenetic disruption of KAT6A phenocopied these effects, with dose-dependent reductions in H3K23pr (28.4% residual at 10 μM) and PD-L1 expression. KAT6A knockdown enhanced T cell-mediated apoptosis, evidenced by increased expression of granzyme B and perforin. Mechanistically, KAT6A loss decreased H3K23pr and reduced RNA polymerase II occupancy on the PD-L1 promoter, leading to suppressed PD-L1 transcription. CRISPR/dCas9-mediated H3K23pr editing at the PD-L1 promoter directly modulated immune evasion, confirming its causal role. Overexpression of PD-L1 mitigated the inhibitory effects of KAT6A knockdown on CRC progression and immune evasion. CONCLUSION: KAT6A drives CRC progression and immune evasion by promoting histone H3 propionylation to epigenetically activate PD-L1 expression. Targeting KAT6A or its downstream H3K23pr-PD-L1 axis represents a promising therapeutic strategy to overcome ICI resistance in CRC.