Biology subjects

Issa, J.-P.

Publications and source records attributed to Issa, J.-P..

6 recordsLinked to original sources

bioRxiv2025

CDK9 degradation Inhibits Gastroesophageal Cancer growth and Overcomes Radiation Resistance by Increasing Chromatin Accessibility and Downregulating YAP1/TEAD signaling

BackgroundGastroesophageal cancer (GEAC) remains a major health burden and urgently needs novel therapeutic targets. The inhibition of CDK9s activity holds the potential to be a highly effective anti-cancer therapeutic. However, the functional role of CDK9, and its potential targeting in GEAC, remain largely unknown. ObjectiveWe aim to evaluate the potential of degradation CDK9 in GEAC treatment and explore its mechanisms. DesignWe evaluated the expression and distribution of CDK9 in GEAC tissue. We designed and synthesized novel CDK9 degraders using proteolysis targeting chimeras (PROTACs) strategy and selected the promising one for further anti-tumor activity evaluation both in vitro and in vivo. We evaluated the effects of CDK9 degradation on epigenetic reactivation, gene expression and chromatin accessibility. We evaluated the co-targeting of CDK9 and YAP/Tead signaling for GEAC treatment, especially for radiation-resistant tumor treatment. ResultsWe demonstrated significantly elevated CDK9 expression in primary GEAC tumor tissues compared to normal tissues, in association with poor survival. We developed a novel CDK9 degrader, YX0597, reducing RNA Pol II Serine 2 phosphorylation, and inhibition MCL-1; this was accompanied by potent inhibition of GEAC cell growth, especially in radiation-resistant tumor cells. Mechanistically, YX0597 strongly enhanced chromatin accessibility, activating epigenetically silenced genes; and dramatically inhibited YAP/TEAD signaling. CDK9 closely interacts with YAP/TEAD signaling, and co-targeting these two mediators could be a novel treatment strategy for the treatment of GEAC. ConclusionOur studies reveal a new avenue for targeting CDK9-hyperactivated GEAC tumors, especially in combination with YAP1/TEAD inhibition in radiation-resistant GEAC tumors. What is already known on this subject?Gastroesophageal cancer (GEAC), the third-leading cause of global cancer death and urgently needs novel targeted therapies. Targeted protein degradation has emerged as an attractive strategy to fight cancer, complementing the activity of traditional small-molecule inhibitors. Cyclin-dependent kinase 9 (CDK9) has been implicated in various cancers. Recently, CDK9 degraders have now been developed for future clinical benefit in targeting tumors with highly activated CDK9. What are the new findings?In this study, we show that CDK9 expression was significantly elevated in primary GEAC tumor tissues including PDXs compared to normal tissues, in association with poor survival. We developed a novel CDK9 degrader XY0597 and proved that it inhibits the progression of GEAC by increasing chromatin accessibility and down-regulating YAP/Tead signaling. We also proved a strong connection between CDK9 and YAP/TEAD signaling and Co-targeting them synergistically inhibits GEAC tumor cell growth, especially in tumors with high YAP signaling activity, such as radiation-resistant cancer. How might it impact on clinical practice in the foreseeable future?Our data suggests that CDK9 is a viable anticancer target in GEAC. We demonstrate that a novel CDK9 degrader, YX0597, has high potential clinical application for GEAC treatment, especially in radiation-resistant cancer. We reveal the crosstalk of CDK9 and YAP/TEAD signaling, and that co-targeting these two mediators could be a new avenue for targeting CDK9-hyperactivated GEAC primary and radiation-resistant tumors.

cancer biology↗

bioRxiv2024

Bone marrow microenvironment signatures associate with patient survival after guadecitabine and atezolizumab therapy in HMA-resistant MDS

Almost 50% of patients with myelodysplastic syndrome (MDS) are refractory to first-line hypomethylating agents (HMAs), which presents a significant clinical challenge considering the lack of options for salvage. Past work revealed that immune checkpoint molecules on peripheral myeloblasts and immune cells are up-regulated after HMA treatment. Therefore, we conducted a Phase I/II clinical trial combining guadecitabine (an HMA) and atezolizumab (an immune checkpoint inhibitor) to treat HMA-relapsed or refractory (HMA-R/R) MDS patients. This combination therapy showed median overall survival of 15.1 months relative to historical controls (4-6 months). Here, we profiled the cell composition and gene expression signatures of cells from bone marrow aspirates from trial participants with short-term (<15 months) or long-term (>15 months) survival at single-cell resolution. Long-term survivors showed a significant reduction of immunosuppressive monocytes, and an expansion of effector lymphocytes after combination therapy. Further immune profiling suggests that gamma delta T cell activation through primed dendritic cells was associated with global interferon activation in the bone marrow microenvironment of long-term survivors. Short-term survivors exhibited elevated inflammation and senescence-like gene signatures that were not resolved by combination therapy. We propose that distinct bone marrow microenvironment features, such as senescence-associated inflammation or immunosuppressive monocyte presence, could improve patient stratification for HMA and immunotherapy combinations in HMA-R/R MDS patients.

cancer biology↗

bioRxiv2024

ZNFX1 is a Novel Master Regulator in Epigenetically-induced Pathogen Mimicry and Inflammasome Signaling in Cancer

DNA methyltransferase and poly(ADP-ribose) polymerase inhibitors (DNMTis, PARPis) induce a stimulator of interferon (IFN) genes (STING)-dependent pathogen mimicry response (PMR) in ovarian (OC) and other cancers. We now show that combining DNMTis and PARPis upregulates expression of a little-studied nucleic-acid sensor, NFX1-type zinc finger-containing 1 protein (ZNFX1). We demonstrate that ZNFX1 is a novel master regulator for PMR induction in mitochondria, serving as a gateway for STING-dependent PMR. In patient OC databases, high ZNFX1 expression levels correlate with advanced stage disease. ZNFX1 expression alone significantly correlates with an increase in overall survival in a phase 3 trial for therapy-resistant OC patients receiving bevacizumab in combination with chemotherapy. In correlative RNA-seq data, inflammasome signaling through ZNFX1 correlates with abnormal vasculogenesis. ZNFX1 controls PMR signaling through the mitochondria and may serve as a biomarker to facilitate offering personalized therapy in OC patients, highlighting the strong translational significance of our findings. Significance statementDNA methyltransferase and poly(ADP-ribose) polymerase inhibitors upregulate expression of a novel nucleic-acid sensor, ZNFX1 that serves as a mitochondrial gateway to STING-dependent interferon/inflammasome signaling with tumor suppressor properties in ovarian cancer.

cancer biology↗

bioRxiv2021

Ultraviolet radiation modulates DNA methylation in melanocytes

Ultraviolet radiation (UVR) is the principal causal factor for melanoma; albeit the underlying mechanisms remain unclear. While the mutagenic properties of UVR are irrefutable, the role of UVR-induced mutations in the initiation of melanoma is controversial which highlights the gap in our knowledge of the initial critical molecular mechanisms of UVR-induced melanomagenesis. To investigate the potential non-mutational mechanisms of UVR-induced melanomagenesis, we studied the role of UVR in modulating DNA methylation changes in melanocytes via next-generation sequencing-based methodologies. Here we show that UVR directly causes stable changes in the DNA methylome and transcriptome, one month after exposure. Genomic features associated with transcription were protected from 5mC alterations whereas CpG sites found in intergenic regions were more likely to be affected. Additionally, the long-term effects of UVR seem to perturb signaling pathways important for melanocyte biology. Interestingly, UVR-sensitive CpG sites were found to be prognostic of overall patient survival and highlighted a subset of CpG sites that may be relevant in melanomagenesis. SignificanceWe report a novel finding that ultraviolet radiation (UVR) induces DNA methylation changes along with stable alterations in gene expression in cultured melanocytes. Our results provide experimental evidence of UVR-induced epigenetic rewiring, which may be implicated in the susceptibility to melanomagenesis, independently of its mutational effects. These findings offer novel insight into the role of UVR in the initiation and pathogenesis of melanoma via a currently underappreciated mechanism.

cancer biology↗

bioRxiv2020

Cellular heterogeneity-adjusted clonal methylation (CHALM) provides better prediction of gene expression

Promoter DNA methylation is a well-established mechanism of transcription repression, but its global correlation with gene expression is surprisingly weak. This weak correlation is due in part to the failure of current methylation quantification methods to consider the heterogeneity among sequenced bulk cells. Here, we introduce Cell Heterogeneity-Adjusted cLonal Methylation (CHALM) as a novel methylation quantification method. CHALM better explains the functional consequences of DNA methylation, such as its correlations with gene expression and H3K4me3. When applied to different methylation datasets, the CHALM method has uniquely detected differentially methylated genes that exhibit distinct biological functions supporting underlying mechanisms.

bioinformatics↗

bioRxiv2019

TET1 and TDG suppress intestinal tumorigenesis by down regulating the inflammatory and immune response pathways

IntroductionAberrant DNA methylation is frequently observed in colorectal cancer (CRC), but the underlying mechanisms are poorly understood. Ten-Eleven Translocation (TET) dioxygenases and DNA repair enzyme Thymine DNA Glycosylase (TDG) are involved in active DNA demethylation by generating and removing, respectively, novel oxidized cytosine species. Mutations of TET1 and TDG, and alterations of the levels of oxidized cytosine species have been identified in human CRC cases, but the biological significance of the TET-TDG demethylation axis in intestinal tumorigenesis is unclear.\n\nMaterial and MethodsWe generated ApcMin mice with additional inactivation of Tet1 and/or Tdg, and characterized the methylome and transcriptome of intestinal adenomas by DREAM and RNA sequencing, respectively.\n\nResultsTet1- and/or Tdg-deficient ApcMin mice show enhanced intestinal tumorigenesis in comparison to wild type Tet1 and Tdg ApcMin mice. Specifically, Tet1 and/or Tdg-deficient ApcMin adenomas manifested increased size or features of erosion and stroma activation. Methylome analysis revealed progressive loss of global DNA hypomethylation in colonic adenomas from Tet1- and Tdg-deficient ApcMin mice, and hypermethylation of CpG islands in Tet1-deficient ApcMin mice. In addition, RNA sequencing showed upregulation of genes in inflammatory and immune response pathways in Tet1-and Tdg-mutant colonic adenomas compared to control ApcMin adenomas.\n\nConclusionsTaken together, these findings demonstrate the important role of active DNA demethylation mediated by TET-TDG in reducing intestinal tumor formation, by modulating the epigenome and inflammatory/immune responses. This study highlights a novel mechanism of epigenetic deregulation during intestinal tumorigenesis with diagnostic, therapeutic and prognostic implications.

cancer biology↗