Promoter methylation of galanin receptors as epigenetic biomarkers for head and neck squamous cell carcinomas

Galanin Receptors (GALR1, GALR2, and GALR3) Immunoexpression in Enteric Plexuses of Colorectal Cancer Patients: Correlation with the Clinico-Pathological Parameters

Galanin (GAL) is an important neurotransmitter released by the enteric nervous system (ENS) neurons located in the muscularis externa and submucosa enteric plexuses that acts by binding to GAL receptors 1, 2 and 3 (GALR1, 2 and 3). In our previous studies, the GAL immunoexpression was compared in colorectal cancer (CRC) tissue and the adjacent parts of the large intestine wall including myenteric and submucosal plexuses. Recently we have also found that expression levels of GALR1 and GALR3 proteins are elevated in CRC tissue as compared with their expression in epithelial cells of unchanged mucosa. Moreover, higher GALR3 immunoreactivity in CRC cells correlated with better prognosis of CRC patients. To understand the distribution of GALRs in enteric plexuses distal and close to CRC invasion, in the present study we decided to evaluate GALRs expression within the myenteric and submucosal plexuses located proximally and distally to the cancer invasion and correlated the GALRs expression levels with the clinico-pathological data of CRC patients. The immunohistochemical and immunofluorescent methods showed only slightly decreased immunoexpression of GALR1 and GALR3 in myenteric plexuses close to cancer but did not reveal any correlation in the immunoexpression of all three GAL receptors in myenteric plexuses and tumour progression. No significant changes were found between the expression levels of GALRs in submucosal plexuses distal and close to the tumour. However, elevated GALR1 expression in submucosal plexuses in vicinity of CRC correlated with poor prognosis, higher tumour grading and shorter overall survival. When myenteric plexuses undergo morphological and functional alterations characteristic for atrophy, GALRs maintain or only slightly decrease their expression status. In contrast, the correlation between high expression of GALR1 in the submucosal plexuses and overall survival of CRC patients suggest that GAL and GALRs can act as a components of local neuro-paracrine pro-proliferative pathways accelerating the invasion and metastasis of cancer cell. The obtained results suggest an important role of GALR1 in submucosal plexuses function during the progression of CRC and imply that GALR1 expression in submucosal plexuses of ENS could be an important predictive factor for CRC progression.

The Galaninergic System: A Target for Cancer Treatment

Simple Summary

Peptidergic systems play an important role in cancer progression. The galaninergic system (the peptide galanin and its receptors: galanin 1, 2 and 3) is involved in tumorigenesis, the invasion and migration of tumor cells and angiogenesis and it has been correlated with tumor stage/subtypes, metastasis and recurrence rate in many types of cancer. Galanin exerts a dual action in tumor cells: a proliferative or an antiproliferative effect depending on the galanin receptor involved in these mechanisms. Galanin receptors could be used in certain tumors as therapeutic targets and diagnostic markers for treatment, prognosis and surgical outcome. This review shows the importance of the galaninergic system in the development of tumors and suggests future promising clinical antitumor applications using galanin agonists or antagonists.

Abstract

The aim of this review is to show the involvement of the galaninergic system in neuroendocrine (phaeochromocytomas, insulinomas, neuroblastic tumors, pituitary tumors, small-cell lung cancer) and non-neuroendocrine (gastric cancer, colorectal cancer, head and neck squamous cell carcinoma, glioma) tumors. The galaninergic system is involved in tumorigenesis, invasion/migration of tumor cells and angiogenesis, and this system has been correlated with tumor size/stage/subtypes, metastasis and recurrence rate. In the galaninergic system, epigenetic mechanisms have been related with carcinogenesis and recurrence rate. Galanin (GAL) exerts both proliferative and antiproliferative actions in tumor cells. GAL receptors (GALRs) mediate different signal transduction pathways and actions, depending on the particular G protein involved and the tumor cell type. In general, the activation of GAL₁R promoted an antiproliferative effect, whereas the activation of GAL₂R induced antiproliferative or proliferative actions. GALRs could be used in certain tumors as therapeutic targets and diagnostic markers for treatment, prognosis and surgical outcome. The current data show the importance of the galaninergic system in the development of certain tumors and suggest future potential clinical antitumor applications using GAL agonists or antagonists.

Prognostic and Immunological Role of PPP1R14A as a Pan-Cancer Analysis Candidate

Despite emerging evidence revealing the remarkable roles of protein phosphatase 1 regulatory inhibitor subunit 14A (PPP1R14A) in cancer tumorigenesis and progression, no pan-cancer analysis is available. A comprehensive investigation of the potential carcinogenic mechanism of PPP1R14A across 33 tumors using bioinformatic techniques is reported for the first time. PPP1R14A is downregulated in major malignancies, and there is a significant correlation between the PPP1R14A expression and the prognosis of patients. The high expression of PPP1R14A in most cases was associated with poor overall survival (OS), disease-specific survival (DSS), and progress-free interval (PFI) across patients with various malignant tumors, including adrenocortical carcinoma (ACC) and bladder urothelial carcinoma (BLCA), indicated through pan-cancer survival analysis. Receiver operating characteristic (ROC) analysis subsequently exhibited that the molecule has high reference significance in diagnosing a variety of cancers. The frequency of PPP1R14A genetic changes including genetic mutations and copy number alterations (CNAs) in uterine carcinosarcoma reached 16.07%, and these alterations brought misfortune to the survival and prognosis of cancer patients. In addition, methylation within the promoter region of PPP1R14A DNA was enhanced in a majority of cancers. Downregulated phosphorylation levels of phosphorylation sites including S26, T38, and others in most cases took place in several tumors, such as breast cancer and colon cancer. PPP1R14A remarkably correlated with the levels of infiltrating cells and immune checkpoint genes. Our research on the carcinogenic effect of PPP1R14A in different tumors is comprehensively summarized and analyzed and provides a theoretical basis for future therapeutic and immunotherapy strategies.

Galanin Receptors (GalR1, GalR2, and GalR3) Expression in Colorectal Cancer Tissue and Correlations to the Overall Survival and Poor Prognosis of CRC Patients

Colorectal cancer (CRC) is the second most common cause of cancer in women and the third in men. The postoperative pathomorphological evaluation of patients with CRC is extremely important for future therapeutic decisions. Although our previous studies demonstrated high galanin (GAL) presence within tumor tissue and an elevated concentration of GAL in the serum of CRC patients, to date, there is a lack of data regarding GAL receptor (GalR) protein expression in CRC cells. Therefore, the aim of this study was to evaluate the presence of all three types of GalRs (GalR1, GalR2 and GalR3) within epithelial cells of the human colon and CRC tissue with the use of the immunohistochemical method and to correlate the results with the clinical-pathological data. We found stronger immunoreactivity of GalR1 and GalR3 in CRC cells compared to epithelial cells of the unchanged mucosa of the large intestine. No differences in the GalR2 protein immunoreactivity between the studied tissues were noted. We also found that the increased immunoexpression of the GalR3 in CRC tissue correlated with the better prognosis and longer survival (p < 0.0079) of CRC patients (n = 55). The obtained results suggest that GalR3 may play the role of a prognostic factor for CRC patients. Based on data from the TCGA-COAD project deposited in the GDC Data Portal, we also found that GalR mRNA in cancer samples and the adjacent normal tissue did not correlate with immunoexpression of the GalR proteins in CRC cells and epithelial cells of the unchanged mucosa.

Galanin mediates tumor-induced immunosuppression in head and neck squamous cell carcinoma

Purpose

Galanin receptor 2 (GALR2) plays a significant role in the progression of head and neck squamous cell carcinomas (HNSCC). Since there is virtually no information on immunomodulation mediated by its ligand in the tumor microenvironment, we assessed the effects of galanin on peripheral blood mononuclear cells (PBMCs).

Methods

After verification of GALR2 expression and it activity in PBMCs we evaluated the effect of galanin and conditioned media from HNSCC cell lines silenced for galanin or antibody-depleted, on proliferation, apoptosis, cytokine expression and activation/differentiation of immune cells.

Results

We found that galanin alone and as a component of the HNSCC secretome decreased HNSCC cell proliferation and expression of pro-inflammatory cytokines (IFNγ, IL-12, IL-17A, IL-1α, IL-6 and TNF-α), whilst increasing apoptosis and expression of pro-tumoral cytokines/growth factors (IL-10, IL-4, PDGF and GM-CSF). T cell activation (using CD69 as activation marker) and anti-tumoral phenotypes in CD4⁺ T cells (Th1 and Th17) were found to be suppressed. In vivo, tumor growth was found to be increased in the presence of galanin-stimulated PBMCs. Data from The Cancer Genome Atlas (TCGA) revealed that high expression of galanin was associated with a reduced overall survival of patients with HNSCC.

Conclusion

Our data indicate that galanin secreted by HNSCC cells exhibits immune-suppressive and pro-tumoral effects.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13402-021-00631-y.

Identification of the Immune-Related Genes in Tumor Microenvironment That Associated With the Recurrence of Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinomas (HNSCC) are still one of the most common malignant tumors in China, with a high metastasis rate and poor prognosis. The tumor immune microenvironment can affect the occurrence, development and prognosis of tumors, but the underlying mechanism is still unclear. In this study, we tried to describe the correlation between the recurrence of HNSCC and the tumor microenvironment (TME). The expression data [estimate the level of tumor stromal and immune infiltration, expression data (ESTIMATE)] algorithm was used to identify and estimate highly correlated stromal cells, immune cells, and prognostic scores in 116 samples of head and neck cancer patients from The Cancer Genome Atlas (TCGA) dataset. The functional enrichment analysis and protein-protein interaction (PPI) networks of differential expressed genes (DEGs) were constructed. Subsequently, the abundance of various infiltrating immune cells was estimated with the tumor immune estimation resource (TIMER) and the infiltration pattern of immune cells were explored in HNSCC. A total of 407 immune-related genes were identified to involve in the TME. We found that CCR5, CD3E, CD4, and HLA -DRB1 were the most obvious DEGs and the dendritic cells (DCs) showed the highest abundance in the TME of HNSCC. In addition, the unsupervised cluster analysis determined 10 clusters of immune infiltration patterns, and indicated that immune infiltrated CD4 + T and B cells may be related to the prognosis of HNSCC. In conclusion, our research determined the list of immune genes and immune infiltrating cells related to the prognosis of HNSCC, and provided a perspective for HNSCC evolution, anti-tumor drugs selection, and drug resistance research.

Functions of galanin, spexin and kisspeptin in metabolism, mood and behaviour

The bioactive peptides galanin, spexin and kisspeptin have a common ancestral origin and their pathophysiological roles are increasingly the subject of investigation. Evidence suggests that these bioactive peptides play a role in the regulation of metabolism, pancreatic β-cell function, energy homeostasis, mood and behaviour in several species, including zebrafish, rodents and humans. Galanin signalling suppresses insulin secretion in animal models (but not in humans), is potently obesogenic and plays putative roles governing certain evolutionary behaviours and mood modulation. Spexin decreases insulin secretion and has potent anorectic, analgesic, anxiolytic and antidepressive-like effects in animal models. Kisspeptin modulates glucose-stimulated insulin secretion, food intake and/or energy expenditure in animal models and humans. Furthermore, kisspeptin is implicated in the control of reproductive behaviour in animals, modulation of human sexual and emotional brain processing, and has antidepressive and fear-suppressing effects. In addition, galanin-like peptide is a further member of the galaninergic family that plays emerging key roles in metabolism and behaviour. Therapeutic interventions targeting galanin, spexin and/or kisspeptin signalling pathways could therefore contribute to the treatment of conditions ranging from obesity to mood disorders. However, many gaps and controversies exist, which must be addressed before the therapeutic potential of these bioactive peptides can be established.

Multifaceted Roles of DNA Methylation in Neoplastic Transformation, from Tumor Suppressors to EMT and Metastasis

Among the major mechanisms involved in tumorigenesis, DNA methylation is an important epigenetic modification impacting both genomic stability and gene expression. Methylation of promoter-proximal CpG islands (CGIs) and transcriptional silencing of tumor suppressors represent the best characterized epigenetic changes in neoplastic cells. The global cancer-associated effects of DNA hypomethylation influence chromatin architecture and reactivation of repetitive elements. Moreover, recent analyses of cancer cell methylomes highlight the role of the DNA hypomethylation of super-enhancer regions critically controlling the expression of key oncogenic players. We will first summarize some basic aspects of DNA methylation in tumorigenesis, along with the role of dysregulated DNA methyltransferases and TET (Ten-Eleven Translocation)-family methylcytosine dioxygenases. We will then examine the potential contribution of epimutations to causality and heritability of cancer. By reviewing some representative genes subjected to hypermethylation-mediated silencing, we will survey their oncosuppressor functions and roles as biomarkers in various types of cancer. Epithelial-to-mesenchymal transition (EMT) and the gain of stem-like properties are critically involved in cancer cell dissemination, metastasis, and therapeutic resistance. However, the driver vs passenger roles of epigenetic changes, such as DNA methylation in EMT, are still poorly understood. Therefore, we will focus our attention on several aspects of DNA methylation in control of EMT and metastasis suppressors, including both protein-coding and noncoding genes.

Prognostic implication of proteomic profiles in head and neck squamous cell carcinoma

BACKGROUND AND OBJECTIVE

Head and neck squamous cell carcinoma (HNSCC) is one of the malignant cancers with poor prognosis. However, clinicopathologic and histological criteria were finite to predict the prognosis of HNSCC. We aimed to characterize the proteomic profile of prognosis from HNSCC patients.

MATERIAL AND METHODS

Reverse phase protein array (RPPA) data in HNSCC were downloaded from The Cancer Proteome Atlas (TCPA). Independent prognostic-related proteins (IPP) were screened by Cox regression model and Kaplan-Meier methods. IPP signature (IPPS) including selected proteins was conducted for prognostic prediction for HNSCC. Protein-protein network analysis and gene ontology (GO) enrichment were used to identify related functional proteins and pathways.

RESULTS

Based on the IPP, IPPS for HNSCC was constructed: risk score = (1.541* IRF1) + (1.460 * SMAD4) + (1.396 * LKB1) + (0.746* Cyclin E2) + (0.618* Paxillin) + (0.499* p-PEA-15 (Ser116)). The IPPS in HNSCC showed good predictive performance (area under curve = 0.779) with moderate sensitivity and specificity. Protein-protein network analysis and functional enrichment indicated an implication of response to decreased oxygen levels in HNSCC.

CONCLUSION

The identified proteomic signature might function as a prognostic tool for the management of HNSCC and provide novel target for the treatment of HNSCC.