Anti-programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) antibodies are currently used in the clinic to interupt the PD-1/PD-L1 immune checkpoint, which reverses T cell dysfunction/exhaustion and shows success in treating cancer. Here, we report a histone demethylase inhibitor, 5-carboxy-8-hydroxyquinoline (IOX1), which inhibits tumour histone demethylase Jumonji domain-containing 1A (JMJD1A) and thus downregulates its downstream β-catenin and subsequent PD-L1, providing an antibody-independent paradigm interrupting the PD-1/PD-L1 checkpoint. Synergistically, IOX1 inhibits cancer cells’ P-glycoproteins (P-gp) through the JMJD1A/β-catenin/P-gp pathway and greatly enhances doxorubicin (DOX)-induced immune-stimulatory immunogenic cell death. As a result, the IOX1 and DOX combination greatly promotes T cell infiltration and activity and significantly reduces tumour immunosuppressive factors. Their liposomal combination reduces the growth of various murine tumours, including subcutaneous, orthotopic, and lung metastasis tumours, and offers a long-term immunological memory function against tumour rechallenging. This work provides a small molecule-based potent cancer chemo-immunotherapy. Some chemotherapeutic drugs, such as doxorubicin, induce immunogenic cell death (ICD) and promote anti-tumor immune responses. Here the authors report that the histone demethylase inhibitor 5-carboxy-8-hydroxyquinoline (IOX1) reduces the expression of PD-L1 in cancer cells and enhances doxorubicin-induced ICD, promoting T cell infiltration and reducing tumor growth in preclinical models.

/pdf/co-delivery-of-iox1-and-doxorubicin-for-antibody-independent-4wgf1btd0i.pdf

Co-delivery of IOX1 and doxorubicin for antibody-independent cancer chemo-immunotherapy.

Hypoxia, a common feature of solid tumors, greatly hinders the efficacy of conventional cancer treatments such as chemo-, radio-, and immunotherapy. The depletion of oxygen in proliferating and advanced tumors causes an array of genetic, transcriptional, and metabolic adaptations that promote survival, metastasis, and a clinically malignant phenotype. At the nexus of these interconnected pathways are hypoxia-inducible factors (HIFs) which orchestrate transcriptional responses under hypoxia. The following review summarizes current literature regarding effects of hypoxia on DNA repair, metastasis, epithelial-to-mesenchymal transition, the cancer stem cell phenotype, and therapy resistance. We also discuss mechanisms and pathways, such as HIF signaling, mitochondrial dynamics, exosomes, and the unfolded protein response, that contribute to hypoxia-induced phenotypic changes. Finally, novel therapeutics that target the hypoxic tumor microenvironment or interfere with hypoxia-induced pathways are reviewed.

https://www.mdpi.com/2073-4409/10/3/678/pdf

Hypoxia-Driven Effects in Cancer: Characterization, Mechanisms, and Therapeutic Implications.

Colorectal cancer (CRC) accounts for almost 10% of all cancer mortality in the United States. The Adenomatous Polyposis Coli (APC) tumor suppressor is mutated in the vast majority of human colorectal cancers (CRC) and leads to deregulated Wnt signaling. Using a novel mouse model in which Apc can be conditionally suppressed using a doxycycline-regulated shRNA, we previously showed that Apc suppression in adenomas and carcinomas drives rapid and widespread tumor-cell differentiation and sustained regression without relapse. However, this study was unable to explore Apc action in metastasis, which is the most common cause of death in CRC patients, since models do not live long enough for metastatic dissemination to occur. To produce a system that would enable further disease progression, we generated a comprehensive panel of colon organoid cultures that reflect iterative combinations of the 3 most common genetic lesions in human CRC: Apc-mut, Apc-mut;KrasG12D, Apc-mut;p53-mut and Apc-mut;KrasG12D;p53-mut. These cultures can be transplanted orthotopically into the colon of recipient mice or seeded in the circulation to assess primary tumor behavior and metastatic dissemination. We show that Apc silencing in organoid culture results in the dysregulated proliferation of stem and progenitor cells but this is reversible upon Apc restoration or pharmacologic inhibition of the Wnt pathway. When engrafted into the colon of recipient mice, these cells create ∼1-3 focal colon tumors that can be tracked using colonoscopy, ultrasound and bioluminescence imaging, and are largely indistinguishable from tumors that develop in transgenic models. Most importantly, triple mutant (Apc/Kras/p53) organoids form invasive adenocarcinoma and colonize the lung following tail vein injection, providing a setting to dissect the importance of Wnt pathway activity in various stages of disease progression. Ultimately, the ability to study cellular and molecular phenotypes in vitro, and assess tumor development in vivo, provides a flexible system to explore the genetic factors underlying CRC progression and metastasis, and overcomes many of the previous technical challenges of modelling advanced CRC. Citation Format: Kevin P. O’Rourke, Lukas E. Dow, Scott W. Lowe. Apc restoration promotes cellular differentiation and reestablishes crypt homeostasis in colorectal cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 666.

Abstract 666: Apc restoration promotes cellular differentiation and reestablishes crypt homeostasis in colorectal cancer

Cancer treatment is a significant challenge for the global health system, although various pharmacological and therapeutic discoveries have been made. It has been widely established that cancer is associated with epigenetic modification, which is reversible and becomes an attractive target for drug development. Adding chemical groups to the DNA backbone and modifying histone proteins impart distinct characteristics on chromatin architecture. This process is mediated by various enzymes modifying chromatin structures to achieve the diversity of epigenetic space and the intricacy in gene expression files. After decades of effort, epigenetic modification has represented the hallmarks of different cancer types, and the enzymes involved in this process have provided novel targets for antitumor therapy development. Epigenetic drugs show significant effects on both preclinical and clinical studies in which the target development and research offer a promising direction for cancer therapy. Here, we summarize the different types of epigenetic enzymes which target corresponding protein domains, emphasize DNA methylation, histone modifications, and microRNA-mediated cooperation with epigenetic modification, and highlight recent achievements in developing targets for epigenetic inhibitor therapy. This article reviews current anticancer small-molecule inhibitors targeting epigenetic modified enzymes and displays their performances in different stages of clinical trials. Future studies are further needed to address their off-target effects and cytotoxicity to improve their clinical translation.

/pdf/small-molecule-inhibitors-overcome-epigenetic-reprogramming-4gi0hmolpd.pdf

Small-Molecule Inhibitors Overcome Epigenetic Reprogramming for Cancer Therapy.

Simple Summary Cancer-associated mortality largely depends on metastatic dissemination. Metastasizing cancer cells exhibit drastic phenotypic changes, including the ability to migrate, invade surrounding tissues, survive in the bloodstream, adapt to different microenvironments, and resist to therapeutic treatments. These changes depend on the genetic reprogramming orchestrated by relatively few players (transcription factors). Among the components of the dimeric transcription factor AP-1, the nuclear oncoprotein Fra-1 is strongly implicated in metastasis mechanisms. Therefore, Fra-1, along with other proinvasive transcription factors, represents an ideal therapeutic target. However, as for other DNA-binding proteins, the design of inhibitory drugs is hampered by the structural features of Fra-1. In this Review, after summarizing the Fra-1 functions and mechanisms of accumulation in invasive tumors, we survey the possible application of multiple strategies and emerging technologies aimed at the inhibition of Fra-1 expression and activity, to prevent metastatic dissemination and therapeutic resistance. Abstract The genetic and epigenetic changes affecting transcription factors, coactivators, and chromatin modifiers are key determinants of the hallmarks of cancer. The acquired dependence on oncogenic transcriptional regulators, representing a major determinant of cancer cell vulnerability, points to transcription factors as ideal therapeutic targets. However, given the unavailability of catalytic activities or binding pockets for small-molecule inhibitors, transcription factors are generally regarded as undruggable proteins. Among components of the AP-1 complex, the FOS-family transcription factor Fra-1, encoded by FOSL1, has emerged as a prominent therapeutic target. Fra-1 is overexpressed in most solid tumors, in response to the BRAF-MAPK, Wnt-beta-catenin, Hippo-YAP, IL-6-Stat3, and other major oncogenic pathways. In vitro functional analyses, validated in onco-mouse models and corroborated by prognostic correlations, show that Fra-1-containing dimers control tumor growth and disease progression. Fra-1 participates in key mechanisms of cancer cell invasion, Epithelial-to-Mesenchymal Transition, and metastatic spreading, by driving the expression of EMT-inducing transcription factors, cytokines, and microRNAs. Here we survey various strategies aimed at inhibiting tumor growth, metastatic dissemination, and drug resistance by interfering with Fra-1 expression, stability, and transcriptional activity. We summarize several tools aimed at the design and tumor-specific delivery of Fra-1/AP-1-specific drugs. Along with RNA-based therapeutics targeting the FOSL1 gene, its mRNA, or cognate regulatory circRNAs, we will examine the exploitation of blocking peptides, small molecule inhibitors, and innovative Fra-1 protein degraders. We also consider the possible caveats concerning Fra-1 inhibition in specific therapeutic contexts. Finally, we discuss a recent suicide gene therapy-based approach, aimed at selectively killing the Fra-1-overexpressing neoplastic cells.

/pdf/the-fra-1-ap-1-oncoprotein-from-the-undruggable-3ctz1g9v.pdf

The Fra-1/AP-1 Oncoprotein: From the “Undruggable” Transcription Factor to Therapeutic Targeting

FOSL1 promotes metastasis of head and neck squamous cell carcinoma through super-enhancer-driven transcription program.

Epigenetic activation of Wnt/β-catenin signaling plays a critical role in Wnt-induced tumorigenesis, notably in colorectal cancers. KDM3 and KDM4 histone demethylases have been reported to promote oncogenic Wnt signaling through demethylation of H3K9 on Wnt target gene promoters and are suggested to be potential therapeutic targets. However, potent inhibitors for these regulators are still not available. In addition, which family is most responsible for activation of Wnt target genes and Wnt-induced oncogenesis is not well documented, specifically in colorectal cancer. In this study, we characterized the functional redundancy and differences between KDM3 and KDM4 in regard to regulating Wnt signaling. Our data suggest that KDM3 may play a more essential role than KDM4 in regulating oncogenic Wnt signaling in human colorectal cancer. We also identified that IOX1, a known histone demethylase inhibitor, significantly suppresses Wnt target gene transcription and colorectal cancer tumorigenesis. Mechanistically, IOX1 inhibits the enzymatic activity of KDM3 by binding to the Jumonji C domain and thereby preventing the demethylation of H3K9 on Wnt target gene promoters. Taken together, our data not only identified the critical mechanisms by which IOX1 suppressed Wnt/β-catenin signaling and colorectal cancer tumorigenesis through inhibition of KDM3, but also suggested that IOX1 may represent an attractive small molecule lead for future drug design and discovery.

/pdf/iox1-suppresses-wnt-target-gene-transcription-and-colorectal-1atnwdp4uz.pdf

IOX1 Suppresses Wnt Target Gene Transcription and Colorectal Cancer Tumorigenesis through Inhibition of KDM3 Histone Demethylases

MiR-21-5p is one of the most common oncogenic miRNAs that is upregulated in many solid cancers by inhibiting its target genes at the posttranscriptional level. However, the upstream regulatory mechanisms of miR-21-5p are still not well documented in cancers. Here, we identify a super-enhancer associated with the MIR21 gene (MIR21-SE) by analyzing the MIR21 genomic regulatory landscape in head and neck squamous cell carcinoma (HNSCC). We show that the MIR21-SE regulates miR-21-5p expression in different HNSCC cell lines and disruption of MIR21-SE inhibits miR-21-5p expression. We also identified that a key transcription factor, FOSL1 directly controls miR-21-5p expression by interacting with the MIR21-SE in HNSCC. Moreover, functional studies indicate that restoration of miR-21-5p partially abrogates FOSL1 depletion-mediated inhibition of cell proliferation and invasion. Clinical studies confirmed that miR-21-5p expression is positively correlated with FOSL1 expression. These findings suggest that FOSL1-SE drives miR-21-5p expression to promote malignant progression of HNSCC.

/pdf/a-super-enhancer-driven-by-fosl1-controls-mir-21-5p-2aasntor94.pdf

Rosalie G. Hoyle

Papers

FOSL1 promotes metastasis of head and neck squamous cell carcinoma through super-enhancer-driven transcription program.

IOX1 Suppresses Wnt Target Gene Transcription and Colorectal Cancer Tumorigenesis through Inhibition of KDM3 Histone Demethylases

A Super-Enhancer Driven by FOSL1 Controls miR-21-5p Expression in Head and Neck Squamous Cell Carcinoma.

Sorting nexin 6 interacts with Cullin3 and regulates programmed death ligand 1 expression.