Project description:Pharmacological inhibition of the SMARCA4 bromodomain inhibited human leukemic cell proliferation, phenocopying SMARCA4 knockdown in these cells. We performed microarray analysis of global gene expression changes in MV4-11 cells after 6 days of PFI-3 treatment and after SMARCA4 knock-down. With this analysis we identified several genes whose expression was similarly up- or down-regulated upon inhibitor treatment and SMARCA4 depletion. Human acute monocytic leukemia cells (MV4-11, ACC 102) were lentivirally transduced with shRNA taregting SMARCA4 (KD) or with a negative control shRNA (Scr). In a parallel experiment MV4-11 cells were treated for 6 days with 10 uM PFI-3, which is SMARCA4, SMARCA2 and PBRM1 bromodomain inhibitor, or DMSO as a negative control. All sample types were prepared in triplicates.
Project description:Pharmacological inhibition of the SMARCA4 bromodomain inhibited human leukemic cell proliferation, phenocopying SMARCA4 knockdown in these cells. We performed microarray analysis of global gene expression changes in MV4-11 cells after 6 days of PFI-3 treatment and after SMARCA4 knock-down. With this analysis we identified several genes whose expression was similarly up- or down-regulated upon inhibitor treatment and SMARCA4 depletion.
Project description:SMARCA2 and SMARCA4 are two mutually exclusive ATPase subunits of SWI/SNF complex. SMARCA4 deficient lung cancer population selectively depend on SMARCA2 for cancer growth phenotype. Rescue experiments with ectopic expression of wild-type, bromodomain mutant and ATPase dead SMARCA2 and SMARCA4 highlight that ATPase domain is the drug target. In this study, we performed genome-wide microarray and differential gene expression profiling on isogenic lung cancer lines expressing cDNA rescue constructs for wild-type, bromodomain mutant and ATPase dead SMARCA2 and SMARCA4
Project description:SMARCA4-deficient thoracic malignancies comprise biologically heterogeneous tumors, ranging from conventional non-small cell lung cancer with SMARCA4 alterations to thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT), an aggressive entity frequently associated with concomitant SMARCA2 loss. However, the extent to which SMARCA4-deficient lung cancer cell lines recapitulate SMARCA4-UT-like biology remains incompletely defined. Here, we characterized lung cancer cell lines across distinct SMARCA4 and SMARCA2 states and identified a subgroup with SMARCA4/2 co-deficiency that exhibited reduced expression of epithelial lineage markers and transcriptional similarity to SMARCA4-UT and other SWI/SNF-deficient malignancies. The EZH1/2 inhibitor HM97662 selectively suppressed growth in SMARCA4/2-deficient cells, with limited effects in SMARCA2-proficient cells. EZH1/2 inhibition broadly reduced H3K27me3 and induced derepression of PRC2 targets regardless of drug sensitivity. However, its biological effects were most pronounced in SMARCA4/2-deficient cells, where it promoted apoptosis, reduced stemness marker expression, attenuated the SMARCA4-UT-associated transcriptional signature, and suppressed MYC/MAX target and cell-cycle programs. Chromatin accessibility analysis further revealed cell-line-specific patterns of accessibility loss, with reduced accessibility at stemness- and lineage-associated transcription factor motif-enriched regions coupled with transcriptional repression of nearby genes in SMARCA4/2-deficient cells. These findings support dual EZH1/2 inhibition as a potential therapeutic vulnerability in SMARCA4/2-deficient, SMARCA4-UT-like lung cancer cells.
Project description:SMARCA4-deficient thoracic malignancies comprise biologically heterogeneous tumors, ranging from conventional non-small cell lung cancer with SMARCA4 alterations to thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT), an aggressive entity frequently associated with concomitant SMARCA2 loss. However, the extent to which SMARCA4-deficient lung cancer cell lines recapitulate SMARCA4-UT-like biology remains incompletely defined. Here, we characterized lung cancer cell lines across distinct SMARCA4 and SMARCA2 states and identified a subgroup with SMARCA4/2 co-deficiency that exhibited reduced expression of epithelial lineage markers and transcriptional similarity to SMARCA4-UT and other SWI/SNF-deficient malignancies. The EZH1/2 inhibitor HM97662 selectively suppressed growth in SMARCA4/2-deficient cells, with limited effects in SMARCA2-proficient cells. EZH1/2 inhibition broadly reduced H3K27me3 and induced derepression of PRC2 targets regardless of drug sensitivity. However, its biological effects were most pronounced in SMARCA4/2-deficient cells, where it promoted apoptosis, reduced stemness marker expression, attenuated the SMARCA4-UT-associated transcriptional signature, and suppressed MYC/MAX target and cell-cycle programs. Chromatin accessibility analysis further revealed cell-line-specific patterns of accessibility loss, with reduced accessibility at stemness- and lineage-associated transcription factor motif-enriched regions coupled with transcriptional repression of nearby genes in SMARCA4/2-deficient cells. These findings support dual EZH1/2 inhibition as a potential therapeutic vulnerability in SMARCA4/2-deficient, SMARCA4-UT-like lung cancer cells.
Project description:Inactivating mutations in SMARCA4 and concurrent epigenetic silencing of SMARCA2 characterize subsets of ovarian and lung cancers. Concomitant loss of these key subunits of SWI/SNF chromatin remodeling complexes in both cancers is associated with chemotherapy resistance and poor prognosis. Here, we discover that SMARCA4/2 loss inhibits chemotherapy-induced apoptosis through disrupting intracellular organelle calcium ion (Ca2+) release in these cancers. By restricting chromatin accessibility to ITPR3, encoding Ca2+ channel IP3R3, SMARCA4/2 deficiency causes reduced IP3R3 expression leading to impaired Ca2+ transfer from the endoplasmic reticulum to mitochondria required for apoptosis induction. Reactivation of SMARCA2 by a histone deacetylase inhibitor rescues IP3R3 expression and enhances cisplatin response in SMARCA4/2-deficient cancer cells both in vitro and in vivo. Our findings elucidate the contribution of SMARCA4/2 to Ca2+-dependent apoptosis induction, which may be exploited to enhance chemotherapy response in SMARCA4/2-deficient cancers.
Project description:We explored the role of SMARCA4 and the two Brahma associated factors SMARCD2 and DPF2 in leukaemia. We observed the selective requirement for these factors for leukemic cell expansion, as well as extended survival of mice transplanted with leukaemic cells with reduced expression of these genes. Gene expression profiling revealed largely similar alterations with the down-regulation of each of these three factors, suggesting a concerted function in transformed blood cells. These changes included loss of pluripotency-associated signature but did not correlate with c-MYC down-regulation. Human acute monocytic leukemia cells (THP-1, ACC 16) were lentivirally transduced with pLKO-puro vectors carrying shRNAs against SMARCA4, SMARCD2 or DPF2. As a negative control, THP-1 cells were transduced with pLKO-puro-shScr (Scrambled). All samples were prepared as biological triplicates.