A chemical genetic screen identifies Aurora kinases as a therapeutic target in EGFR T790M negative, gefitinib-resistant head and neck squamous cell carcinoma (HNSCC)

Targeting IL-6/STAT3 signaling abrogates EGFR-TKI resistance through inhibiting Beclin-1 dependent autophagy in HNSCC

Head and neck squamous cell carcinoma (HNSCC) is featured by notorious EGFR tyrosine kinase inhibitor (TKI) resistance attributable to activation of parallel pathways. The numerous phase I/II trials have rarely shown encouraging clinical outcomes of EGFR-TKIs during treatment in HNSCC patients with advanced tumors. A unique IL-6/STAT3 signaling axis is reported to regulate multiple cancer-related pathways, but whether this signaling is correlated with reduced EGFR-TKI responsiveness is unclear. Here, we found that STAT3 signaling is compensatorily upregulated after EGFR-TKI exposure and confers anti-EGFR therapy resistance during HNSCC therapy. Targeting STAT3 using small molecule inhibitors promotes complete recovery or sustained elimination of HNSCC tumors through combination with EGFR-TKIs both in vitro and in diverse animal models. Mechanistically, phosphorylated STAT3 was proven to enhance oncogenic autophagic flux, protecting cancer cells and preventing EGFR-TKI-induced tumor apoptosis. Thus, blockade of STAT3 signaling simultaneously disrupts several key interactions during tumor progression and remodels the autophagic degradation system, thereby rendering advanced HNSCC eradicable through combination with EGFR-TKI therapy. These findings provide a clinically actionable strategy and suggest STAT3 as a predictive biomarker with therapeutic potential for EGFR-TKI resistant HNSCC patients.

Circadian Regulator-Mediated Molecular Subtypes Depict the Features of Tumor Microenvironment and Indicate Prognosis in Head and Neck Squamous Cell Carcinoma

Introduction

Circadian rhythm is involved in multiple biological activities and implicated in cancer development. However, the role of circadian rhythm in head and neck squamous cell carcinoma (HNSCC) has not been fully interpreted yet. Herein, the present study set out to explore the significance of circadian regulator genes (CRGs) in HNSCC.

Materials and Methods

The molecular landscape and clinical significance of 13 CRGs in HNSCC were explored based on The Cancer Genome Atlas (TCGA). The biological functions of PER3, a key CRG, were validated by cellular experiments. The correlation of CRGs with microenvironment, pathway activities, and prognosis was determined by bioinformatic algorithms. A novel circadian score was introduced to evaluate the circadian modification pattern of each patient and further validated in an independent cohort from the Gene Expression Omnibus (GEO) dataset.

Results

CRGs presented high heterogeneity in HNSCC at both genomic and transcriptomic levels. Specifically, PER3 indicated a better prognosis and inhibited HNSCC cell proliferation. Moreover, HNSCC tissues displayed three circadian regulator patterns with distinct clinical outcomes, transcriptomic characteristics, and microenvironment features. Circadian score was an independent risk factor and exhibited excellent predictive efficiency in both the training cohort from the TCGA database and the validation cohort from the GEO database.

Conclusions

CRGs played an indispensable role in HNSCC development. An in-depth exploration of circadian rhythm would improve the understanding of HNSCC carcinogenesis and confer novel insights for future clinical practices.

Single cell analysis in head and neck cancer reveals potential immune evasion mechanisms during early metastasis

Profiling tumors at single-cell resolution provides an opportunity to understand complexities underpinning lymph-node metastases in head and neck squamous-cell carcinoma. Single-cell RNAseq (scRNAseq) analysis of cancer-cell trajectories identifies a subpopulation of pre-metastatic cells, driven by actionable pathways including AXL and AURK. Blocking these two proteins blunts tumor invasion in patient-derived cultures. Furthermore, scRNAseq analyses of tumor-infiltrating CD8 + T-lymphocytes show two distinct trajectories to T-cell dysfunction, corroborated by their clonal architecture based on single-cell T-cell receptor sequencing. By determining key modulators of these trajectories, followed by validation using external datasets and functional experiments, we uncover a role for SOX4 in mediating T-cell exhaustion. Finally, interactome analyses between pre-metastatic tumor cells and CD8 + T-lymphocytes uncover a putative role for the Midkine pathway in immune-modulation and this is confirmed by scRNAseq of tumors from humanized mice. Aside from specific findings, this study demonstrates the importance of tumor heterogeneity analyses in identifying key vulnerabilities during early metastasis.

Emerging tyrosine kinase inhibitors for head and neck cancer

INTRODUCTION

Conventional regimens for head and neck squamous cell carcinoma (HNSCC) are limited in efficacy and are associated with adverse toxicities. Food and Drug Administration (FDA) approved molecular targeting agents include the HER1 (EGFR)-directed monoclonal antibody cetuximab and the immune checkpoint inhibitors nivolumab and pembrolizumab. However, clinical benefit is only seen in roughly 15-20% of HNSCC patients treated with these agents. New molecular targeting agents are needed that either act with monotherapeutic activity against HNSCC tumors or enhance the activities of current therapies, particularly immunotherapy. Small-molecule tyrosine kinase inhibitors (TKIs) represent a viable option toward this goal.

AREAS COVERED

This review provides an update on TKIs currently under investigation in HNSCC. We focus our review on data obtained and trials underway in HNSCC, including salivary gland cancers and nasopharyngeal carcinomas, but excluding thyroid cancer and esophageal cancer.

EXPERT OPINION

While some emerging TKIs have shown clinical benefit, the positive effects have, largely, been modest. The design of clinical trials of TKIs has been hampered by a lack of understanding of biomarkers that can be used to define patient populations most likely to respond. Further preclinical and translational studies to define biomarkers of TKI response will be critically important.

Identification and Characterization of Natural and Semisynthetic Quinones as Aurora Kinase Inhibitors

Aurora kinases (Aurora A, B, and C) are a family of serine/threonine kinases that play critical roles during mitotic initiation and progression. Aurora A and B kinases are ubiquitously expressed, and their overexpression and/or amplification in many cancers have been associated with poor prognosis. Several inhibitors that target Aurora kinases A, B, or both have been developed during the past decade with efficacy in different in vitro and in vivo models for a variety of cancers. Recent studies have also identified Aurora A as a synthetic lethal target for different tumor suppressors, including RB1, SMARCA4, and ARID1A, which signifies the need for Aurora-A-selective inhibitors. Here, we report the screening of a small library of quinones (nine naphthoquinones, one orthoquinone, and one anthraquinone) in a biochemical assay for Aurora A kinase that resulted in the identification of several quinones as inhibitors. IC₅₀ determination against Aurora A and B kinases revealed the inhibition of both kinases with selectivity toward Aurora A. Two of the compounds, natural quinone naphthazarin (1) and a pseudo anthraquinone, 2-(chloromethyl)quinizarin (11), potently inhibited the proliferation of various cancer cell lines with IC₅₀ values ranging from 0.16 ± 0.15 to 1.7 ± 0.06 and 0.15 ± 0.04 to 6.3 ± 1.8 μM, respectively. Treatment of cancer cells with these compounds for 24 h resulted in abrogated mitosis and apoptotic cell death. Direct binding of both the compounds with Aurora A kinase was also confirmed through STD NMR analysis. Docking studies predicted the binding of both compounds to the ATP binding pocket of Aurora A kinase. We have, therefore, identified quinones as Aurora kinase inhibitors that can serve as a lead for future drug discovery endeavors.

Antiproliferative Activity of a New Quinazolin-4(3H)-One Derivative via Targeting Aurora Kinase A in Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the most common lung cancer subtype. Although chemotherapy and targeted therapy are used for the treatment of patients with NSCLC, the survival rate remains very low. Recent findings suggested that aurora kinase A (AKA), a cell cycle regulator, is a potential target for NSCLC therapy. Previously, we reported that a chemical entity of quinazolin-4(3H)-one represents a new template for AKA inhibitors, with antiproliferative activity against cancer cells. A quinazolin-4(3H)-one derivative was further designed and synthesized in order to improve the pharmacokinetic properties and antiproliferation activity against NSCLC cell lines. The derivative, BIQO-19 (Ethyl 6-(4-oxo-3-(pyrimidin-2-ylmethyl)-3,4-dihydroquinazolin-6-yl)imidazo [1,2-a]pyridine-2-carboxylate), exhibited improved solubility and antiproliferative activity in NSCLC cells, including epidermal growth factor receptor–tyrosine kinase inhibitor (EGFR-TKI)-resistant NSCLC cells. BIQO-19 effectively inhibited the growth of the EGFR-TKI-resistant H1975 NSCLC cells, with the suppression of activated AKA (p-AKA) expression in these cells. The inhibition of AKA by BIQO-19 significantly induced G₂/M phase arrest and subsequently evoked apoptosis in H1975 cells. In addition, the combination of gefitinib and BIQO-19 exhibited synergistic antiproliferative activity in NSCLC cells. These findings suggest the potential of BIQO-19 as a novel therapeutic agent for restoring the sensitivity of gefitinib in EGFR-TKI-resistant NSCLC cells.

Aurora Kinases as Therapeutic Targets in Head and Neck Cancer

ABSTRACT

The Aurora kinases (AURKA and AURKB) have attracted attention as therapeutic targets in head and neck squamous cell carcinomas. Aurora kinases were first defined as regulators of mitosis that localization to the centrosome (AURKA) and centromere (AURKB), governing formation of the mitotic spindle, chromatin condensation, activation of the core mitotic kinase CDK1, alignment of chromosomes at metaphase, and other processes. Subsequently, additional roles for Aurora kinases have been defined in other phases of cell cycle, including regulation of ciliary disassembly and DNA replication. In cancer, elevated expression and activity of Aurora kinases result in enhanced or neomorphic locations and functions that promote aggressive disease, including promotion of MYC expression, oncogenic signaling, stem cell identity, epithelial-mesenchymal transition, and drug resistance. Numerous Aurora-targeted inhibitors have been developed and are being assessed in preclinical and clinical trials, with the goal of improving head and neck squamous cell carcinoma treatment.

EGFR and PI3K Pathway Activities Might Guide Drug Repurposing in HPV-Negative Head and Neck Cancers

While genetic alterations in Epidermal growth factor receptor (EGFR) and PI3K are common in head and neck squamous cell carcinomas (HNSCC), their impact on oncogenic signaling and cancer drug sensitivities remains elusive. To determine their consequences on the transcriptional network, pathway activities of EGFR, PI3K, and 12 additional oncogenic pathways were inferred in 498 HNSCC samples of The Cancer Genome Atlas using PROGENy. More than half of HPV-negative HNSCC showed a pathway activation in EGFR or PI3K. An amplification in EGFR and a mutation in PI3KCA resulted in a significantly higher activity of the respective pathway (p = 0.017 and p = 0.007). Interestingly, both pathway activations could only be explained by genetic alterations in less than 25% of cases indicating additional molecular events involved in the downstream signaling. Suitable in vitro pathway models could be identified in a published drug screen of 45 HPV-negative HNSCC cell lines. An active EGFR pathway was predictive for the response to the PI3K inhibitor buparlisib (p = 6.36E-03) and an inactive EGFR and PI3K pathway was associated with efficacy of the B-cell lymphoma (BCL) inhibitor navitoclax (p = 9.26E-03). In addition, an inactive PI3K pathway correlated with a response to multiple Histone deacetylase inhibitor (HDAC) inhibitors. These findings require validation in preclinical models and clinical studies.