Biology subjects

Myers, J. N.

Publications and source records attributed to Myers, J. N..

4 recordsLinked to original sources

bioRxiv2021

KMT2D Loss Promotes Head and Neck Squamous Cell Carcinoma Through Enhancer Reprogramming and Modulation of Immune Microenvironment

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, with 5-year survival of [~]50%. Genomic profiling studies have identified important somatic mutations in this disease which presents an opportunity for precision medicine. We demonstrate that KMT2D, a histone methyltransferase harbors somatic mutations in [~]17% of HNSCC and is associated with 2-year recurrence in TCGA data. Consistent with algorithmic prediction of bring a driver tumor-suppressor event, its loss results in larger oral tumors in immune-proficient orthotopic models. Mechanistically, we find that KMT2D knockdown or KMT2D mutation causes loss of H3K4me1-marked enhancers harboring IRF7/9 binding sites, which is known to regulate interferon signaling. Indeed, KMT2D loss in human and murine cell lines deregulated transcriptional levels of cytokine expression and impacted numerous immune signaling pathways, including interferon signaling. Consistently, Kmt2d knockdown in murine tumors exhibited decrease in IFN{gamma}-producing effector T cells and an increase in T-cells with an exhausted phenotype. Epistasis experiments showed that exogenous treatment with IFN{gamma} abrogated the increased tumor growth in Kmt2d-deficient oral tumors. Together, these results support the role of KMT2D as a tumor suppressor in HNSCC that regulates the tumor microenvironment by modulating H3K4me1-marked enhancers controlling interferon signaling.

cancer biology↗

bioRxiv2021

High Enhancer Activity is an Epigenetic Feature of HPV Negative Atypical Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous disease with significant morbidity and mortality and frequent recurrence. Pre-NGS efforts to transcriptionally classify HNSCC into groups of varying prognosis have identified four accepted molecular subtypes of disease: Atypical (AT), Basal (BA), Classical (CL), and Mesenchymal (MS). Here, we investigated the active enhancer landscapes of these subtypes using representative HNSCC cell lines and identified samples belonging to the AT subtype as having increased enhancer activity compared to the other 3 HNSCC subtypes. Cell lines belonging to atypical subtype were more resistant to bromodomain inhibitors (BETi). PRO-Seq experiments that both TCGA tumors and AT cell lines showed higher eRNA transcripts for enhancers controlling BETi resistance pathways, such as lipid metabolism and MAPK signaling. Additionally, HiChIP experiments suggested higher enhancer-promoter (E-P) contacts in the AT subtype, including on genes identified in the eRNA analysis. Consistently, known BETi resistance pathways were upregulated upon exposure to these inhibitors. Together, our results identify that the AT subtype of HNSCC is associated with high enhancer activity, resistance to BET inhibition, and signaling pathways that could serve as future targets for sensitizing HNSCC to BET inhibition.

cancer biology↗

bioRxiv2020

Loss of Caspase-8 function in combination with SMAC mimetic treatment sensitizes Head and Neck Squamous Carcinoma to radiation through induction of necroptosis

Caspase-8 (CASP8) is one of the most frequently mutated genes in head and neck squamous carcinomas (HNSCC), and mutations of CASP8 are associated with poor overall survival. The distribution of these mutations in HNSCC suggests that they are likely to be inactivating. Inhibition of CASP8 has been reported to sensitize cancer cells to necroptosis, a unique cell death mechanism. Here, we evaluated how CASP8 regulates necroptosis in HSNCC using cell line models and syngeneic mouse xenografts. In vitro, knockdown of CASP8 rendered HNSCCs susceptible to necroptosis induced by a second mitochondria-derived activator of caspase (SMAC) mimetic, Birinapant, when combined with pan-caspase inhibitors Z-VAD-FMK or Emricasan. Strikingly, inhibition of CASP8 function via knockdown or Emricasan treatment was associated with enhanced radiation killing by Birinapant through induction of necroptosis. In a syngeneic mouse model of oral cancer, Birinapant, particularly when combined with radiation delayed tumor growth and enhanced survival under CASP8 loss. Exploration of molecular underpinnings of necroptosis sensitivity confirmed that the level of functional receptor-interacting serine/threonine-protein kinase-3 (RIP3), a key enzyme in the necroptosis pathway was crucial in determining susceptibility to this mode of death. Although an in vitro screen revealed that many HNSCC cell lines were resistant to necroptosis due to low levels of RIP3, patient tumors maintain RIP3 expression and should therefore remain sensitive. Collectively, these results suggest that targeting the necroptosis pathway with SMAC mimetics, especially in combination with radiation, may be a relevant therapeutic approach in HNSCC with compromised CASP8 status, provided that RIP3 function is maintained. SignificanceCASP8 status regulates necroptotic death in HNSCC and this pathway can be exploited therapeutically.

cancer biology↗

bioRxiv2020

CREBBP/EP300 mutation is associated with poor outcome in HNSCC and targetable with synthetic cytotoxicity.

Despite radiation forming the curative backbone of over 50% of malignancies, there are no genomically-driven radiation sensitizers for clinical use. We performed in vivo shRNA screening to identify targets generally associated with radiation response as well as those exhibiting a genomic dependency. This identified the histone acetyltransferases CREBBP/EP300 as a target for radiosensitization in combination with radiation in cognate mutant tumors. Further in vitro and in vivo studies confirmed this phenomenon was due to repression of homologous recombination following DNA damage and can be reproduced using chemical inhibition of histone acetyltransferase (HAT), but not bromodomain function. Selected mutations in CREBBP lead to a hyperacetylated state that increases CBP and BRCA1 acetylation, representing a gain of function targets by HAT inhibition. Additionally, mutations in CREBBP/EP300 were associated with recurrence following radiation, in several squamous cell carcinoma cohorts. These findings represent both a novel mechanism of treatment resistance and the potential for genomically-driven treatment.

cancer biology↗