Retinoic acid-related orphan receptor C isoform 2 expression and its prognostic significance for non-small cell lung cancer

Targeting Nuclear Receptors in Lung Cancer—Novel Therapeutic Prospects

Lung cancer, the second most commonly diagnosed cancer, is the major cause of fatalities worldwide for both men and women, with an estimated 2.2 million new incidences and 1.8 million deaths, according to GLOBOCAN 2020. Although various risk factors for lung cancer pathogenesis have been reported, controlling smoking alone has a significant value as a preventive measure. In spite of decades of extensive research, mechanistic cues and targets need to be profoundly explored to develop potential diagnostics, treatments, and reliable therapies for this disease. Nuclear receptors (NRs) function as transcription factors that control diverse biological processes such as cell growth, differentiation, development, and metabolism. The aberrant expression of NRs has been involved in a variety of disorders, including cancer. Deregulation of distinct NRs in lung cancer has been associated with numerous events, including mutations, epigenetic modifications, and different signaling cascades. Substantial efforts have been made to develop several small molecules as agonists or antagonists directed to target specific NRs for inhibiting tumor cell growth, migration, and invasion and inducing apoptosis in lung cancer, which makes NRs promising candidates for reliable lung cancer therapeutics. The current work focuses on the importance of various NRs in the development and progression of lung cancer and highlights the different small molecules (e.g., agonist or antagonist) that influence NR expression, with the goal of establishing them as viable therapeutics to combat lung cancer.

Advances in the Study of Circadian Genes in Non-Small Cell Lung Cancer

Circadian genes regulate several physiological functions such as circadian rhythm and metabolism and participate in the cytogenesis and progression of various malignancies. The abnormal expression of these genes in non-small cell lung cancer (NSCLC) is closely related to the clinicopathological features of NSCLC and may promote or inhibit NSCLC progression. Circadian rhythm disorders and clock gene abnormalities may increase the risk of lung cancer in some populations. We collected 15 circadian genes in NSCLC, namely PER1, PER2, PER3, TIMELESS, Cry1, Cry2, CLOCK, BMAL1/ARNTL-1, ARNTL2, NPAS2, NR1D1(REV-ERB), DEC1, DEC2, RORα, and RORγ, and determined their relationships with the clinicopathological features of patients and the potential mechanisms promoting or inhibiting NSCLC progression. We also summarized the studies on circadian rhythm disorders and circadian genes associated with lung cancer risk. The present study aimed to provide theoretical support for the future exploration of new therapeutic targets and for the primary prevention of NSCLC from the perspective of circadian genes. Interpretation of circadian rhythms in lung cancer could guide further lung cancer mechanism research and drug development that could lead to more effective treatments and improve patient outcomes.

Loss of retinoic acid receptor-related receptor alpha (Rorα) promotes the progression of UV-induced cSCC

Cutaneous squamous cell carcinoma (cSCC) is prevalent in the world, accounting for a huge part of non-melanoma skin cancer. Most cSCCs are associated with a distinct pre-cancerous lesion, the actinic keratosis (AK). However, the progression trajectory from normal skin to AK and cSCC has not been fully demonstrated yet. To identify genes involved in this progression trajectory and possible therapeutic targets for cSCC, here we constructed a UV-induced cSCC mouse model covering the progression from normal skin to AK to cSCC, which mimicked the solar UV radiation perfectly using the solar-like ratio of UVA and UVB, firstly. Then, transcriptome analysis and a series of bioinformatics analyses and cell experiments proved that Rorα is a key transcript factor during cSCC progression. Rorα could downregulate the expressions of S100a9 and Sprr2f in cSCC cells, which can inhibit the proliferation and migration in cSCC cells, but not the normal keratinocyte. Finally, further animal experiments confirmed the inhibitory effect of cSCC growth by Rorα in vivo. Our findings showed that Rorα would serve as a potential novel target for cSCC, which will facilitate the treatment of cSCC in the future.

Identification and Validation of Immune-Related Gene Prognostic Signature for Hepatocellular Carcinoma

Immune-related genes (IRGs) have been identified as critical drivers of the initiation and progression of hepatocellular carcinoma (HCC). This study is aimed at constructing an IRG signature for HCC and validating its prognostic value in clinical application. The prognostic signature was developed by integrating multiple IRG expression data sets from TCGA and GEO databases. The IRGs were then combined with clinical features to validate the robustness of the prognostic signature through bioinformatics tools. A total of 1039 IRGs were identified in the 657 HCC samples. Subsequently, the IRGs were subjected to univariate Cox regression and LASSO Cox regression analyses in the training set to construct an IRG signature comprising nine immune-related gene pairs (IRGPs). Functional analyses revealed that the nine IRGPs were associated with tumor immune mechanisms, including cell proliferation, cell-mediated immunity, and tumorigenesis signal pathway. Concerning the overall survival rate, the IRGPs distinctly grouped the HCC samples into the high- and low-risk groups. Also, we found that the risk score based on nine IRGPs was related to clinical and pathologic factors and remained a valid independent prognostic signature after adjusting for tumor TNM, grade, and grade in multivariate Cox regression analyses. The prognostic value of the nine IRGPs was further validated by forest and nomogram plots, which revealed that it was superior to the tumor TNM, grade, and stage. Our findings suggest that the nine-IRGP signature can be effective in determining the disease outcomes of HCC patients.

Hepatitis B Virus X Protein-Induced RORγ Expression to Promote the Migration and Proliferation of Hepatocellular Carcinoma

Aberrant expression of RORγ is implicated in cancer development. A previous study identified that RORγ functions as a tumor promoter to drive hepatocellular carcinoma (HCC) growth. However, its expression and significance in HCC remain unclear. The central finding of this work is that RORγ was overexpressed in HCC due to its dysfunction of promoter methylation, and hepatitis B virus X protein (HBx) can remarkably induce the expression of RORγ in hepatocellular carcinoma through enhancing the transcriptional function. Also, the HBx-induced RORγ could promote the migration and proliferation of hepatoma cells. Hence, these results suggest that RORγ was an important regulator in HCC, and our finding provides new insights into the significance of RORγ in HCC.

Retinoic Acid Receptor-Related Orphan Receptors: Critical Roles in Tumorigenesis

Retinoic acid receptor-related orphan receptors (RORs) include RORα (NR1F1), RORβ (NR1F2), and RORγ (NR1F3). These receptors are reported to activate transcription through ligand-dependent interactions with co-regulators and are involved in the development of secondary lymphoid tissues, autoimmune diseases, inflammatory diseases, the circadian rhythm, and metabolism homeostasis. Researches on RORs contributing to cancer-related processes have been growing, and they provide evidence that RORs are likely to be considered as potential therapeutic targets in many cancers. RORα has been identified as a potential therapeutic target for breast cancer and has been investigated in melanoma, colorectal colon cancer, and gastric cancer. RORβ is mainly expressed in the central nervous system, but it has also been studied in pharyngeal cancer, uterine leiomyosarcoma, and colorectal cancer, in addition to neuroblastoma, and recent studies suggest that RORγ is involved in various cancers, including lymphoma, melanoma, and lung cancer. Some studies found RORγ to be upregulated in cancer tissues compared with normal tissues, while others indicated the opposite results. With respect to the mechanisms of RORs in cancer, previous studies on the regulatory mechanisms of RORs in cancer were mostly focused on immune cells and cytokines, but lately there have been investigations concentrating on RORs themselves. Thus, this review summarizes reports on the regulation of RORs in cancer and highlights potential therapeutic targets in cancer.

Targeting protein for Xenopus kinesin-like protein 2 knockdown enhances radiation sensitivity of human lung squamous carcinoma cell

The targeting protein for Xenopus kinesin-like protein 2 (TPX2) has been demonstrated to be associated with the tumourigenesis of many cancers. In the present study, we investigated the role and preliminary mechanism of TPX2 in the resistance of lung squamous carcinoma to radiation therapy. The results showed that SK-MES-1R and NCI-H226R cells were more resistant to X-ray irradiation than the parental cells (SK-MES-1 and NCI-H226). Moreover, TPX2 was upregulated in the radioresistant cells compared with the parental cells. TPX2 knockdown significantly decreased TPX2 expression in SK-MES-1 cells, while TPX2 overexpression increased TPX2 expression in NCI-H226 cells compared with the corresponding control cells. TPX2 knockdown enhanced the radiosensitivity of SK-MES-1 and promoted cell apoptosis following exposure to irradiation, whereas TPX2 overexpression decreased the radiosensitivity of NCI-H226 and inhibited cell apoptosis. In in vivo studies, the combination of TPX2 knockdown and irradiation significantly inhibited tumour growth, decreased tumour weight, downregulated TPX2 expression in tumour tissue and induced cell apoptosis in nude mice, while TPX2 overexpression exerted an opposite effect. Our results indicated that TPX2 was correlated with cell radioresistance and it might be served as a therapeutic target to enhance cell radiosensitivity in the radiation therapy of lung squamous carcinoma.

IL-17 Promotes Angiogenic Factors IL-6, IL-8, and Vegf Production via Stat1 in Lung Adenocarcinoma

Inflammation and angiogenesis are two hallmarks of carcinoma. The proinflammatory cytokine interleukin-17 (IL-17) facilitates angiogenesis in lung cancer; however, the underlying mechanism is not fully understood. In this study, tumour microvessel density (MVD) was positively associated with IL-17, interleukin-6 (IL-6), interleukin-8 (IL-8), and vascular endothelial cell growth factor (VEGF) expression in human lung adenocarcinoma tissues, and it was increased in tumour tissues of A549-IL-17 cell-bearing nude mice. Importantly, positive correlations were also detected between IL-17 expression and IL-6, IL-8 and VEGF expression in human lung adenocarcinoma tissues. Furthermore, IL-6, IL-8 and VEGF production, as well as STAT1 phosphorylation, were increased in tumour tissues of A549-IL-17 cell-bearing nude mice in vivo and in A549 and H292 cells following IL-17 stimulation in vitro. In addition, STAT1 knockdown using an inhibitor and siRNA attenuated the IL-17-mediated increases in IL-6, IL-8 and VEGF expression in A549 and H292 cells. In conclusion, IL-17 may promote the production of the angiogenic inducers IL-6, IL-8 and VEGF via STAT1 signalling in lung adenocarcinoma.

The IL-17-Th1/Th17 pathway: an attractive target for lung cancer therapy?

INTRODUCTION

There is strong pharmaceutical development of agents targeting the IL-17-TH17 pathway for the treatment of psoriasis (Ps) and psoriatic arthritis (PsA). Lung cancer accounts for 28% of all cancer-related deaths worldwide, and roughly 80% of patients with newly-diagnosed non-small cell lung cancer (NSCLC) present with metastatic disease, with a poor prognosis of around 12 months. Therefore, there is a high unmet medical need for the development of new and potent systemic treatments in this deadly disease. The emergence of immunotherapies such as anti-PD-1 or anti-PDL1 as candidate therapies in non-small cell lung cancer (NSCLC) indicates that targeting critical immuno-modulatory cytokines including those within the IL-17-Th1/Th17 axis may have proven benefit in the treatment of lung cancer. Areas covered: In this review we describe the current evidence for aberrant IL-17-Th1/Th17 settings in cancer, particularly with regard to targeting this axis in NSCLC. We further discuss the current agents under pharmaceutical development which could potentially target this axis, and discuss the current limitations and areas of concern regarding the use of these in lung cancer. Expert opinion: Current evidence suggests that moving forward agents targeting the IL-17-Th1/Th17 pathway may have novel new oncoimmunology indications in the treatment paradigm for NSCLC.