Sensitivity has been a key issue for Enhancer of zeste homolog 2 (EZH2) inhibitors in cancer therapy. The EZH2 inhibitor EPZ-6438 was first approved by the US Food and Drug Administration (FDA) in 2020. However, its inadequate anti-cancer activity in solid tumors limits its clinical application. In this study, we utilized the multiple cancer cell lines, which are less sensitive to the EZH2 inhibitor GSK126, combining animal model and clinical data to investigate the underlying mechanism. IncuCyte S3 was used to explore the difference in the responsiveness of hematological tumor cells and solid tumor cells to GSK126. Transcriptome and metabolome of B16F10 cells after GSK126 treatment were analyzed and the distinct changes in the metabolic profile were revealed. Real-time quantitative PCR and western blot experiments were used to further verify the multi-omics data. ChIP-qPCR was performed to detected H3K27me3 enrichment of target genes. Finally, the anti-tumor effects of combining GSK126 and lipid metabolism drugs were observed with IncuCyte S3 platform, CCK-8 and animal model respectively. We found that although the proliferative phenotype did not show strong difference upon treatment with GSK126, the transcriptome and metabolome changed profoundly. GSK126 treatment led to broad shifts in glucose, amino acid, and lipid metabolism. Lipid synthesis was strengthened manifested by the increasing abundance of unsaturated fatty acids. SCD1 and ELOVL2 were regulated by H3K27me3 at gene regulatory region, and upregulated by EZH2 knockdown and inhibitors. SCD1 knockdown increased cellular sensitivity to GSK126. Based on the findings above, the application of the combination with SCD1 inhibitor significantly attenuated the proliferation of cancer and increased the sensitivity to GSK126 by suppressing desaturation of fatty acids. Dysregulated lipid metabolism can blunt the sensitivity of cancer cells to GSK126. These characteristics shed light on the novel combination therapy strategies to combat tumor resistance. National Natural Science Foundation of China (No. 81672091, No.91749107 and No. 81972966).

Ovarian cancer (OC) is the most aggressive and lethal gynaecological cancer and is characterised by abnormal lipid metabolism. Enhancer of zeste homologue 2 (EZH2) is the catalytic subunit of polycomb repressive complex 2 (PRC2). It functions as a tumour promoter through both canonical H3K27me3 modification and noncanonical mechanisms. Although EZH2 has been developed as a potential anticancer target, the therapeutic effects of EZH2 inhibitors in solid tumours are still limited. The levels of fatty acid and tricarboxylic acid (TCA) cycle-related metabolites were measured via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). EZH2-knockout cells, ChIP‒qPCR, qPCR, and western blotting were used to investigate the regulatory effect of EZH2 on FADS2. The expression of FADS2 transcript variants and their correlations with prognosis in clinical OC tissues were analysed via the GEPIA 2 database. Various OC cell lines, patient-derived organoids and tumour-bearing models have been used to test the therapeutic effects of EZH2 and FADS2 inhibitors. 4D-DIA proteomics, the Seahorse assay and flow cytometry-based detection of mitochondrial function and protein synthesis were performed to explore the mechanism of combined therapy. EZH2 knockout increased FADS2 variant 1 (v1) and decreased variant 2/3 (v2/3) at both the mRNA and protein levels. EZH2 occupied the promoters of FADS2 v1 and v2/3, but the enrichment of H3K27me3 at the v2/v3 promoter was significantly lower than that at the v1 promoter. Furthermore, EZH2 inhibitors increased full-length FADS2 v1 expression and polyunsaturated fatty acid abundance in OC cells. A high FADS2 v1/v2 ratio was associated with poor prognosis in patients with OC. Targeting FADS2 with shRNAs or inhibitors reduced EZH2 levels and sensitised cancer cells to EZH2 inhibitors. The combined inhibition of EZH2 and FADS2 induced mitochondrial dysfunction and energy stress and synergised to reduce tumour growth in vitro and in vivo. EZH2 inhibition increases the proportion of the full FADS2 isoform through differential regulation, which suggests a poor prognosis in OC patients. Simultaneous inhibition of EZH2 and FADS2 causes mitochondrial dysfunction and energy stress in OC, resulting in a more pronounced antitumour effect. Our study reveals a mechanistic connection between EZH2 and FADS2 and provides a potential therapeutic strategy for OC. This work was supported by the Youth Program of the National Natural Science Foundation of China (No. 82203102, No. 82303801, No. 82203433), the National Key Research and Development Program of China (2022YFA1104001), the General Program of the National Natural Science Foundation of China (No. 82272745, No. 82072870, No. 81972966, No. 82373173, No. 82073057), and the Peking University Third Hospital Clinical Key Project (BYSY2022069, BYSY2022070, BYSYZD2023010).

Identification of Novel Immunologic Checkpoint Gene Prognostic Markers for Ovarian Cancer: Ovarian cancer has a higher resistance to chemotherapy, displaying the highest mortality rate among gynecological cancers. Recently, immune checkpoint inhibitor therapy is an effective treatment for selected patients. However, a low response rate for immune checkpoint treatment was observed for ovarian cancer patients. Therefore, it is necessary to identify ovarian cancer patients who might gain benefits from immune checkpoint treatment. Datasets containing ovarian cancer samples with mRNA-seq and clinical follow-up data were downloaded from different databases like The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). The researchers applied the univariate analysis for selecting the immune checkpoint genes (ICGs) at a significance level of as the candidate ICGs. The Spearman correlation coefficients were calculated to compare the correlation between tumor mutation burden and candidate ICGs, and the Kaplan-Meier plots were generated. They also assessed the external validation datasets and the results of immunohistochemical staining. 46 and 35 ICGs were extracted from the TCGA and GEO datasets, respectively, and we categorized the ICGs into 3 expression patterns. Nine (TCGA) and three (GEO) ICGs were significantly related to the prognosis. Univariate survival analysis indicated a significant prognostic relationship between the expression levels of ICOS, TIGIT, and TNFRSF8 and overall survival (OS). Moreover, the expression of ICOS and TIGIT also presented a significantly positive relationship with the CD8A expression. Importantly, patients with a higher CD8A and ICOS expression level (ICOS-H/CD8A-H) showed a better survival rate compared to other patients. Stratified analysis using TIGIT, TNFRSF8, and CD8A expression also showed an improved prognosis for the high TIGIT/high CD8A expression subgroup and the low TNFRSF8/low CD8A expression subgroup compared to the other subgroups. This study identified different immune subtypes that can predict the OS of ovarian cancer patients. This data could prove to be beneficial for making important clinical decisions and designing individual immunotherapeutic strategies.

Pancreatic cancer, characterized by an unfavourable prognosis, necessitates early diagnosis and prompt therapeutic intervention. This study aimed to delineate the functional implications of m6A/m1A/m5C‐related genes in pancreatic carcinogenesis and establish a prognostic model. Utilizing data from the TCGA‐PAAD cohort (n=178) combined with GTEx normal pancreatic tissues (n=332), we identified 43 genes associated with m ⁶ A/m ¹ A/m ⁵ C methylation pathways. Significant expression differences in these genes were observed between neoplastic and non‐neoplastic tissues, correlating with multiple biological pathways. Consensus clustering divided pancreatic cancer patients into two distinct molecular subtypes exhibiting pronounced survival differences. A prognostic risk‐scoring model was developed based on nine m ⁶ A/m ¹ A/m ⁵ C‐related genes, demonstrating efficacy in predicting patient outcomes. We constructed a nomogram integrating clinical variables with the risk score to enhance prognostic precision. Among these genes, a comprehensive investigation was conducted using immunohistochemistry and multicolor immunofluorescence to elucidate that higher TRMT61B expression in tumour tissues is significantly associated with higher pancreatic cancer stage, and might relate to an immunosuppressive and dysfunctional tumour immune microenvironment. This study reveals the role of m ⁶ A/m ¹ A/m ⁵ C associated genes, especially TRMT61B, in the epigenetic regulation of pancreatic cancer, providing evidence supporting their potential as novel prognostic biomarkers.