ABSTRACT
Mutations of the SWI/SNF chromatin remodeling complex occur in 20% of all human cancers, including ovarian cancer. Approximately half of ovarian clear cell carcinomas (OCCC) carry mutations in the SWI/SNF subunit ARID1A, while small cell carcinoma of the ovary hypercalcemic type (SCCOHT) presents with inactivating mutations of the SWI/SNF ATPase SMARCA4 alongside epigenetic silencing of the ATPase SMARCA2. Loss of these ATPases disrupts SWI/SNF chromatin remodeling activity and may also interfere with the function of other histone-modifying enzymes that associate with or are dependent on SWI/SNF activity. One such enzyme is lysine-specific histone demethylase 1 (LSD1/KDM1A), which regulates the chromatin landscape and gene expression by demethylating proteins such as histone H3. Cross-cancer analysis of the TCGA database shows that LSD1 is highly expressed in SWI/SNF-mutated tumors. SCCOHT and OCCC cell lines have shown sensitivity to the reversible LSD1 inhibitor SP-2577 (Seclidemstat), suggesting that SWI/SNF-deficient ovarian cancers are dependent on LSD1 activity. Moreover, it has been shown that inhibition of LSD1 stimulates interferon (IFN)-dependent anti-tumor immunity through induction of endogenous retroviral elements and may thereby overcome resistance to checkpoint blockade. In this study, we investigated the ability of SP-2577 to promote anti-tumor immunity and T-cell infiltration in SCCOHT and OCCC cell lines. We found that SP-2577 stimulated IFN-dependent anti-tumor immunity in SCCOHT and promoted the expression of PD-L1 in both SCCOHT and OCCC. Together, these findings suggest that the combination therapy of SP-2577 with checkpoint inhibitors may induce or augment immunogenic responses of SWI/SNF-mutated ovarian cancers and warrants further investigation.
Subject(s)
Antineoplastic Agents/pharmacology , Chromosomal Proteins, Non-Histone/genetics , DNA-Binding Proteins/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , T-Lymphocytes/drug effects , Transcription Factors/antagonists & inhibitors , Transcription Factors/genetics , B7-H1 Antigen/genetics , B7-H1 Antigen/metabolism , Carcinoma, Small Cell/genetics , Carcinoma, Small Cell/pathology , Cell Line, Tumor , Cell Proliferation/drug effects , Culture Media, Conditioned/chemistry , Culture Media, Conditioned/pharmacology , DNA Helicases/genetics , DNA Helicases/metabolism , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Female , Gene Expression Regulation/drug effects , Histones/genetics , Histones/metabolism , Humans , Interferons/pharmacology , Mutation , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Ovarian Neoplasms/genetics , Ovarian Neoplasms/immunology , Ovarian Neoplasms/pathology , T-Lymphocytes/cytology , T-Lymphocytes/immunology , Transcription Factors/metabolismABSTRACT
At the M2 terminal of the macrophage activation spectrum, expression of genes is regulated by transcription factors that include STAT6, CREB, and C/EBPß. Signaling through ß-adrenergic receptors drives M2 activation of macrophages, but little is known about the transcription factors involved. In the present study, we found that C/EBPß regulates the signaling pathway between ß-adrenergic stimulation and expression of Arg1 and several other specific genes in the greater M2 transcriptome. ß-adrenergic signaling induced Cebpb gene expression relatively early with a peak at 1â¯h post-stimulation, followed by peak Arg1 gene expression at 8â¯h. C/EBPß transcription factor activity was elevated at the enhancer region for Arg 1 at both 4 and 8â¯h after stimulation but not near the more proximal promoter region. Knockdown of Cebpb suppressed the ß-adrenergic-induced peak in Cebpb gene expression as well as subsequent accumulation of C/EBPß protein in the nucleus, which resulted in suppression of ß-adrenergic-induced Arg1 gene expression. Analysis of genome-wide transcriptional profiles identified 20 additional M2 genes that followed the same pattern of regulation by ß-adrenergic- and C/EBPß-signaling. Promoter-based bioinformatic analysis confirmed enrichment of binding motifs for C/EBPß transcription factor across these M2 genes. These findings pinpoint a mechanism that may be targeted to redirect the deleterious influence of ß-adrenergic signaling on macrophage involvement in M2-related diseases such as cancer.
