Targeting FAT1 Inhibits Carcinogenesis, Induces Oxidative Stress and Enhances Cisplatin Sensitivity through Deregulation of LRP5/WNT2/GSS Signaling Axis in Oral Squamous Cell Carcinoma

Recent advances in the role of atypical cadherin FAT1 in tumorigenesis (Review)

The FAT atypical cadherin 1 (FAT1) gene is the ortholog of the Drosophila fat gene and encodes the protocadherin FAT1. FAT1 belongs to the cadherin superfamily, a group of full-length membrane proteins that contain cadherin-like repeats. In various types of human cancer, FAT1 is one of the most commonly mutated genes, and is considered to be an emerging cancer biomarker and a potential target for novel therapies. However, the biological functions of FAT1 and the precise downstream signaling pathways that it mediates have remained to be fully elucidated. The present review discussed the current literature on FAT1, focusing on FAT1 mutations and expression levels, and their impact on signaling pathways and mechanisms in various types of cancer, including both solid tumors and hematological malignancies, such as esophageal squamous cell carcinoma, head and neck squamous cell carcinoma, lung squamous cell carcinoma, hepatocellular carcinoma, glioma, breast cancer, acute lymphoblastic leukemia, acute myeloid leukemia, lymphoma and myeloma. The present review aimed to provide further insights and research directions for future studies on FAT1 as an oncogenic factor or tumor suppressor.

FAT1 knockdown enhances the CSC properties of HNSCC through p-CaMKII-mediated inactivation of the IFN pathway

FAT atypical cadherin 1 (FAT1), which encodes an atypical cadherin-coding protein, has a high mutation rate and is commonly regarded as a tumor suppressor gene in head and neck squamous cell carcinoma (HNSCC). Nonetheless, the potential regulatory mechanisms by which FAT1 influences the progression of HNSCC remain unresolved. In this context, we reported that FAT1 was downregulated in tumor tissues/cells compared with normal tissues/cells and that it was correlated with the clinicopathological features and prognosis of HNSCC. Knockdown of FAT1 enhanced cancer stem cell (CSC) properties and decreased the percentage of apoptotic tumor cells. Mechanistically, FAT1 knockdown increased the phosphorylation levels of Ca2+/calmodulin-dependent protein kinase II (CaMKII), subsequently resulting in diminished interaction between phosphorylated STAT1 and interferon regulatory factor 9 (IRF9), which inactivated the interferon pathway and facilitated the adoption of the malignant phenotype of HNSCC cells. The overexpression of STAT1 and IRF9 alleviated the malignant behavior caused by FAT1 inhibition. In summary, our study reveals the role of FAT1 in suppressing the CSC properties of HNSCC via the CaMKII/STAT1/IRF9 pathway, and that targeting FAT1 might be a promising treatment for HNSCC.

Connecting the dots: investigating the link between environmental, genetic, and epigenetic influences in metabolomic alterations in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) accounts for around 90% of all oral cancers and is the eighth most common cancer worldwide. Despite progress in managing OSCC, the overall prognosis remains poor, with a survival rate of around 50-60%, largely due to tumor size and recurrence. The challenges of late-stage diagnosis and limitations in current methods emphasize the urgent need for less invasive techniques to enable early detection and treatment, crucial for improving outcomes in this aggressive form of oral cancer. Research is currently aimed at unraveling tumor-specific metabolite profiles to identify candidate biomarkers as well as discover underlying pathways involved in the onset and progression of cancer that could be used as new targets for diagnostic and therapeutic purposes. Metabolomics is an advanced technological approach to identify metabolites in different sample types (biological fluids and tissues). Since OSCC promotes metabolic reprogramming influenced by a combination of genetic predisposition and environmental factors, including tobacco and alcohol consumption, and viral infections, the identification of distinct metabolites through screening may aid in the diagnosis of this condition. Moreover, studies have shown the use of metabolites during the catalysis of epigenetic modification, indicating a link between epigenetics and metabolism. In this review, we will focus on the link between environmental, genetic, and epigenetic influences in metabolomic alterations in OSCC. In addition, we will discuss therapeutic targets of tumor metabolism, which may prevent oral tumor growth, metastasis, and drug resistance.

Targeting ferroptosis as a potential strategy to overcome the resistance of cisplatin in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a crucial public health problem, accounting for approximately 2% of all cancers globally and 90% of oral malignancies over the world. Unfortunately, despite the achievements in surgery, radiotherapy, and chemotherapy techniques over the past decades, OSCC patients still low 5-year survival rate. Cisplatin, a platinum-containing drug, serves as one of the first-line chemotherapeutic agents of OSCC. However, the resistance to cisplatin significantly limits the clinical practice and is a crucial factor in tumor recurrence and metastasis after conventional treatments. Ferroptosis is an iron-based form of cell death, which is initiated by the intracellular accumulation of lipid peroxidation and reactive oxygen species (ROS). Interestingly, cisplatin-resistant OSCC cells exhibit lower level of ROS and lipid peroxidation compared to sensitive cells. The reduced ferroptosis in cisplatin resistance cells indicates the potential relationship between cisplatin resistance and ferroptosis, which is proved by recent studies showing that in colorectal cancer cells. However, the modulation pathway of ferroptosis reversing cisplatin resistance in OSCC cells still remains unclear. This article aims to concisely summarize the molecular mechanisms and evaluate the relationship between ferroptosis and cisplatin resistance OSCC cells, thereby providing novel strategies for overcoming cisplatin resistance and developing new therapeutic approaches.

Tislelizumab plus nimotuzumab is effective against recurrent or metastatic oral squamous cell carcinoma among patients with a performance status score ≥ 2: a retrospective study

Objectives

The efficacy of treatments targeting recurrent or metastatic head and neck squamous cell carcinoma are unsatisfactory in practice for patients with a ECOG PS score ≥ 2. Thus, this study retrospectively evaluated the safety and efficacy of a programmed cell death 1 inhibitor (tislelizumab) combined with an epidermal growth factor receptor inhibitor (nimotuzumab) in treating patients with a PS score ≥ 2 who suffer from recurrent or metastatic oral squamous cell carcinoma (OSCC).

Materials and methods

Fifteen patients were treated with tislelizumab (200 mg IV Q3W) and nimotuzumab (200 mg IV Q3W). Programmed cell death-ligand 1 (PD-L1) expression in tumor biopsies was assessed with immunohistochemistry. Whole-exome sequencing was used to evaluate treatment efficacy based on PD-L1 expression and gene mutation.

Results

At a median follow-up of 9.6 months, median overall survival was 10.1 months, and median progression-free survival was 4.0 months. Overall response rate was 40%, with 6/15 patients achieving partial response. Eight patients exhibited nine adverse events, eight out of nine being grade 2 and the remaining being grade 3. Whole-exome sequencing showed that DYNC1I2, THSD7A, and FAT1 mutations were associated with patient prognosis.

Conclusion

Combination therapy involving tislelizumab plus nimotuzumab is a promising, low-toxicity treatment for recurrent or metastatic OSCC in patients with a PS score ≥ 2.

Protumorigenic role of the atypical cadherin FAT1 by the suppression of PDCD10 via RelA/miR221-3p/222-3p axis in glioblastoma

The atypical cadherin FAT1 function either as a pro or antitumorigenic in tumors of different tissue origins. Our group previously demonstrated the protumorigenic nature of FAT1 signaling in glioblastoma (GBM). In this study, we investigated how FAT1 influences the expression of clustered oncomiRs (miR-221-3p/miR-222-3p) and their downstream effects in GBM. Through several experiments involving the measurement of specific gene/microRNA expression, gene knockdowns, protein and cellular assays, we have demonstrated a novel oncogenic signaling pathway mediated by FAT1 in glioma. These results have been verified using antimiRs and miR-mimic assays. Initially, in glioma-derived cell lines (U87MG and LN229), we observed FAT1 as a novel up-regulator of the transcription factor NFκB-RelA. RelA then promotes the expression of the clustered-oncomiRs, miR-221-3p/miR-222-3p, which in turn suppresses the expression of the tumor suppressor gene (TSG), PDCD10 (Programmed cell death protein10). The suppression of PDCD10, and other known TSG targets (PTEN/PUMA), by miR-221-3p/miR-222-3p, leads to increased clonogenicity, migration, and invasion of glioma cells. Consistent with our in-vitro findings, we observed a positive expression correlation of FAT1 and miR-221-3p, and an inverse correlation of FAT1 and the miR-targets (PDCD10/PTEN/PUMA), in GBM tissue-samples. These findings were also supported by publicly available GBM databases (The Cancer Genome Atlas [TCGA] and The Repository of Molecular Brain Neoplasia Data [Rembrandt]). Patients with tumors displaying high levels of FAT1 and miR-221-3p expression (50% and 65% respectively) experienced shorter overall survival. Similar results were observed in the TCGA-GBM database. Thus, our findings show a novel FAT1/RelA/miR-221/miR-222 oncogenic-effector pathway that downregulates the TSG, PDCD10, in GBM, which could be targeted therapeutically in a specific manner.

Predictive capacity of FAT1 transcriptional expression in patients with head and neck squamous cell carcinomas treated with radiotherapy

OBJECTIVE

To analyze the predictive capacity at the primary location of the tumor of the FAT1 transcriptional expression in patients with head and neck squamous cell carcinoma treated with radiotherapy.

MATERIAL AND METHODS

We conducted a retrospective study from biopsies of the primary location of the tumor in 82 patients with head and neck squamous cell carcinoma treated with radiotherapy. The transcriptional expression of FAT1 was determined by RT-PCR. The level of FAT1 transcriptional expression was categorized according to the local control after radiotherapy using a recursive partitioning analysis.

RESULTS

Elevated FAT1 transcriptional expression was associated with an increased risk of local recurrence after radiotherapy. Patients with a high expression level of FAT1 (n=18; 22.0%) had a 5-year local recurrence-free survival of 42.1% (95% CI: 18.6%-65.6%), whereas for patients with a low expression (n=64; 78.0%) it was 72.4% (95% CI: 61.5%-83.3%) (p=0.002). According to the result of a multivariate analysis, patients with a high FAT1 expression category had a 2.3-fold increased risk of local recurrence (95% CI: 1.0-5.2; p=0.043).

CONCLUSIONS

Elevated FAT1 transcriptional expression was associated with a significantly increased risk of local recurrence in patients with head and neck squamous cell carcinoma treated with radiotherapy.

The FAT1 Cadherin Drives Vascular Smooth Muscle Cell Migration

Vascular smooth muscle cells (VSMCs) are normally quiescent and non-migratory, regulating the contraction and relaxation of blood vessels to control the vascular tone. In response to arterial injury, these cells become active; they proliferate, secrete matrix proteins, and migrate, and thereby contribute importantly to the progression of several cardiovascular diseases. VSMC migration specifically supports atherosclerosis, restenosis after catheter-based intervention, transplant vasculopathy, and vascular remodeling during the formation of aneurysms. The atypical cadherin FAT1 is expressed robustly in activated VSMCs and promotes their migration. A positive role of FAT1 in the migration of other cell types, including neurons, fibroblasts, podocytes, and astrocyte progenitors, has also been described. In cancer biology, however, the effect of FAT1 on migration depends on the cancer type or context, as FAT1 either suppresses or enhances cancer cell migration and invasion. With this review, we describe what is known about FAT1's effects on cell migration as well as the factors that influence FAT1-dependent migration. In VSMCs, these factors include angiotensin II, which activates FAT1 expression and cell migration, and proteins of the Atrophin family: Atrophin-1 and the short isoform of Atrophin-2, which promote VSMC migration, and the long isoform of Atrophin-2, which exerts negative effects on FAT1-dependent VSMC migration.

Genome-wide DNA methylation profiling of HPV-negative leukoplakia and gingivobuccal complex cancers

BACKGROUND

Gingivobuccal complex oral squamous cell carcinoma (GBC-OSCC) is an aggressive malignancy with high mortality often preceded by premalignant lesions, including leukoplakia. Previous studies have reported genomic drivers in OSCC, but much remains to be elucidated about DNA methylation patterns across different stages of oral carcinogenesis.

RESULTS

There is a serious lack of biomarkers and clinical application of biomarkers for early detection and prognosis of gingivobuccal complex cancers. Hence, in search of novel biomarkers, we measured genome-wide DNA methylation in 22 normal oral tissues, 22 leukoplakia, and 74 GBC-OSCC tissue samples. Both leukoplakia and GBC-OSCC had distinct methylation profiles as compared to normal oral tissue samples. Aberrant DNA methylation increases during the different stages of oral carcinogenesis, from premalignant lesions to carcinoma. We identified 846 and 5111 differentially methylated promoters in leukoplakia and GBC-OSCC, respectively, with a sizable fraction shared between the two sets. Further, we identified potential biomarkers from integrative analysis in gingivobuccal complex cancers and validated them in an independent cohort. Integration of genome, epigenome, and transcriptome data revealed candidate genes with gene expression synergistically regulated by copy number and DNA methylation changes. Regularised Cox regression identified 32 genes associated with patient survival. In an independent set of samples, we validated eight genes (FAT1, GLDC, HOXB13, CST7, CYB5A, MLLT11, GHR, LY75) from the integrative analysis and 30 genes from previously published reports. Bisulfite pyrosequencing validated GLDC (P = 0.036), HOXB13 (P < 0.0001) promoter hypermethylation, and FAT1 (P < 0.0001) hypomethylation in GBC-OSCC compared to normal controls.

CONCLUSIONS

Our findings identified methylation signatures associated with leukoplakia and gingivobuccal complex cancers. The integrative analysis in GBC-OSCC identified putative biomarkers that enhance existing knowledge of oral carcinogenesis and may potentially help in risk stratification and prognosis of GBC-OSCC.

The Potential of Liquid Biopsy in Detection of Endometrial Cancer Biomarkers: A Pilot Study

Endometrial cancer belongs to the most common gynecologic cancer types globally, with increasing incidence. There are numerous ways of classifying different cases. The most recent decade has brought advances in molecular classification, which show more accurate prognostic factors and the possibility of personalised adjuvant treatment. In addition, diagnostic approaches lag behind these advances, with methods causing patients discomfort while lacking the reproducibility of tissue sampling for biopsy. Minimally invasive liquid biopsies could therefore represent an alternative screening and diagnostic approach in patients with endometrial cancer. The method could potentially detect molecular changes in this cancer type and identify patients at early stages. In this pilot study, we tested such a detection method based on circulating tumour DNA isolated from the peripheral blood plasma of 21 Slovak endometrial cancer patients. We successfully detected oncomutations in the circulating DNA of every single patient, although the prognostic value of the detected mutations failed to offer certainty. Furthermore, we detected changes associated with clonal hematopoiesis, including DNMT3A mutations, which were present in the majority of circulating tumour DNA samples.

Somatic mutations in FAT cadherin family members constitute an underrecognized subtype of colorectal adenocarcinoma with unique clinicopathologic features

BACKGROUND

The FAT cadherin family members (FAT1, FAT2, FAT3 and FAT4) are conserved tumor suppressors that are recurrently mutated in several types of human cancers, including colorectal carcinoma (CRC).

AIM

To characterize the clinicopathologic features of CRC patients with somatic mutations in FAT cadherin family members.

METHODS

We analyzed 526 CRC cases from The Cancer Genome Atlas PanCancer Atlas dataset. CRC samples were subclassified into 2 groups based on the presence or absence of somatic mutations in FAT1, FAT2, FAT3 and FAT4. Individual clinicopathological data were collected after digital slide review. Statistical analysis was performed using t tests and chi-square tests.

RESULTS

This CRC study cohort had frequent mutations in the FAT1 (10.5%), FAT2 (11.2%), FAT3 (15.4%) and FAT4 (23.4%) genes. Two hundred CRC patients (38.0%) harbored somatic mutations in one or more of the FAT family genes and were grouped into the FAT mutated CRC subtype. The FAT-mutated CRC subtype was more commonly located on the right side of the colon (51.0%) than in the rest of the cohort (30.1%, P < 0.001). It showed favorable clinicopathologic features, including a lower rate of positive lymph nodes (pN1-2: 33.5% vs 46.4%, P = 0.005), a lower rate of metastasis to another site or organ (pM1: 7.5% vs 16.3%, P = 0.006), and a trend toward an early tumor stage (pT1-2: 25.0% vs 18.7%, P = 0.093). FAT somatic mutations were significantly enriched in microsatellite instability CRC (28.0% vs 2.1%, P < 0.001). However, FAT somatic mutations in microsatellite stable CRC demonstrated similar clinicopathologic behaviors, as well as a trend of a better disease-free survival rate (hazard ratio = 0.539; 95% confidence interval: 0.301-0.967; log-rank P = 0.073).

CONCLUSION

FAT cadherin family genes are frequently mutated in CRC, and their mutation profile defines a subtype of CRC with favorable clinicopathologic characteristics.

Potential predictive value of comutant LRP1B and FAT for immune response in non-small cell lung cancer: LRP1B and FAT comutation enhance immune response

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Patients with co-occurring mutations in LRP1B and FAT1/2/3/4 revealed a relatively higher TMB level compared with single LRP1B and FAT mutation groups.

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Patients with EGFR mutation were prone to produce a weaker TMB level and less co-occurring mutation in LRP1B and FAT1/2/3/4, which might be correlated with immunosuppressive tumor microenvironment.

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LRP1B and FAT members showed specifically enriched T cell-inflamed genes and the co-occurring mutant TP53 status in NSCLC patients who harbor LRP1B/FAT comutations.

Background

Preliminary investigation revealed that Low-density lipoprotein receptor-related protein 1b (LRP1B) and FAT atypical cadherin (FAT) family mutation might serve as immune regulators under certain tumor microenvironment.

Experimental design

We curated a total of 70 non-small cell lung cancer (NSCLC) patients who harbored alterations in LRP1B and/or FAT family (FAT1/2/3/4) based on next-generation sequencing (NGS) to analyze multiple-dimensional data types, including comutant status, tumor mutation burden (TMB), programmed death receptor ligand 1 (PD-L1) expression, T cell-inflamed gene expression profiling (GEP) and therapy response.

Results

20 patients with co-occurring mutations in LRP1B and FAT1/2/3/4 revealed a relatively higher TMB level of 17.05 mut/Mb compared with 7.60 mut/Mb and 8.80 mut/Mb in single LRP1B and FAT mutation groups, respectively. LRP1B and FAT members showed specifically enriched T cell-inflamed genes and the co-occurring mutant TP53 status in NSCLC patients who harbor LRP1B/FAT comutations.

Conclusions

This work provides evidence that co-occurring mutations of LRP1B and FAT in NSCLC may serve as a group of potential predictive factors in guiding immunotherapy on the basis of their association with TMB status.

FAT1 Upregulates in Oral Squamous Cell Carcinoma and Promotes Cell Proliferation via Cell Cycle and DNA Repair

Objective

Previous studies have revealed that FAT atypical cadherin 1 (FAT1) plays a tumor-suppressive or oncogenic role in a context-dependent manner in various cancers. However, the functions of FAT1 are ambiguous in tumorigenesis owing to inconsistent research in oral squamous cell carcinoma (OSCC). The present study aimed at gaining an insight into the role of FAT1 in the tumor genesis and development.

Methods

The expression, mutant, and survival data analyses were done using data from The Cancer Genome Atlas (TCGA), the Gene Expression Omnibus (GEO), and the Clinical Proteomic Tumor Analysis Consortium (CPTAC) database, verified with clinical samples via real-time polymerase chain reaction (qRT-PCR), Western blot (WB), and immunohistochemical (IHC) staining. OSCC cells transfected with siRNA were employed for in vitro assessment in cell proliferation, apoptosis, and migration ability in appropriate ways. The underlying mechanism was explored by RNA sequencing after FAT1 silencing.

Results

Overall, FAT1 significantly increased in OSCC with a poor prognosis outcome. The in vitro experiment showed the promoting effect of FAT1 in the proliferation and migration of OSCC cells. FAT1 can also inhibit both the early and late apoptosis of OSCC cells. RNA-sequencing analysis of FAT1 silencing revealed that the cell cycle, DNA replication, and some core genes (MCM2, MCM5, CCNE1 SPC24, MYBL2, KIF2C) may be the potential mechanism in OSCC.

Conclusions

FAT1 may act as an oncogene in OSCC with potential mechanism influencing the cell cycle and DNA repair.

Analysis of senescence in gingival tissues and gingival fibroblast cultures

Objective

To determine senescence‐associated changes in the gingival tissues of aged mice and gingival fibroblast cultures.

Materials and Methods

The production of senescence‐associated β‐galactosidase (SA‐β‐gal) and mRNA expression of p16, p21, interleukin (IL)‐1β, and tumor necrosis factor α (TNF‐α) were evaluated in gingival tissues, gingival fibroblasts of 10‐ and 20‐month‐old C57BL/6NCrl mice, and multiple‐passaged and hydrogen peroxide‐stimulated human gingival fibroblasts (HGFs). Changes in molecular expression in HGF cultures due to senescent cell elimination by the senolytic drug ABT‐263 (Navitoclax) were analyzed.

Results

Compared to 10‐week‐old mice, the 20‐month‐old mice had higher numbers of M1 macrophages. The proportion of cells expressing SA‐β‐gal were also higher in 20‐ month‐old mice than in 10‐week‐old‐mice. Gingival fibroblasts in 20‐month‐old mice expressed less collagen 1a1, collagen 4a1, and collagen 4a2 mRNA than those in 10‐week‐old mice. Compared to control cells, H2O2 treated HGF cells expressed higher levels of SA‐β‐gal and p16, p21, IL‐1β, and TNF‐α. Furthermore, ABT‐263 suppressed HGF cell expression of cytokines after senescence induction.

Conclusions

Senescence‐associated changes were observed in the gingival tissues of aged mice and HGF cultures. In addition, the potential of senolytic drugs to modify aging‐related changes in the gingiva was shown.

Clinical significance of FAT1 gene mutation and mRNA expression in patients with head and neck squamous cell carcinoma

The FAT1 gene functions as a tumor suppressor or promoter and remains incompletely understood. We examined the clinical significance of FAT1 in head and neck squamous cell carcinoma (HNSCC) using four publicly available HNSCC cohorts and one HNSCC cohort enrolled at a tertiary medical center. We developed FAT1 signatures reflecting FAT1 mutations and mRNA expression using one cohort. Patients with HNSCC were classified into FAT1-associated low risk (FAT1-LR; n = 195) and FAT1-associated high risk (FAT1-HR; n = 371) subgroups. The five-year overall survival and recurrence-free survival rates were significantly lower in the FAT1-HR subgroup than in the FAT1-LR subgroup (P = 0.01 and 0.003, respectively). The clinical significance of FAT1 was validated using four independent cohorts. Cox proportional hazards models showed that the FAT1 signature was an independent prognostic factor for HNSCC patients. In addition, FAT1 signature was associated with the response to radiotherapy, advanced stage, and human papilloma virus (HPV) status in HNSCC patients. In conclusion, the FAT1 gene signature was associated with prognosis of HNSCC and may help to provide personalized treatments for HNSCC patients.

Genetic Alteration and Their Significance on Clinical Events in Small Cell Lung Cancer

Introduction

Small cell lung cancer (SCLC), an aggressive subtype of lung cancer characterized by the development of neuroendocrine tumors, is prone to distant metastasis, resistant to platinum-based drugs and has a poor prognosis. The development of next-generation sequencing technology (NGS) has led to the identification of many genetic alterations in SCLC. Few druggable targeted molecules can be used in clinical practice. Currently, NGS is widely employed in routine clinical practice of non-small cell lung cancer to assist in therapeutic options and prognosis evaluation. This study aims to investigate genes involved in small cell lung cancer (SCLC), their occurrence and their significance in clinical events.

Methods

Tumor tissue specimens from 18 Chinese SCLC patients were collected through a 520 cancer‐related genes panel for next-generation sequencing. First, the association between sequence results and clinical outcomes was examined. Subsequently, data on clinical pathology and sequencing results were analyzed.

Results

The Kaplan–Meier curve displayed a significant reduction in PFS for SCLC patients with LRP1B or MAP3K13 mutations. Overall survival (OS) of SCLC patients with MSH6 mutation was significantly higher than those with SPEN mutation.

Conclusion

Next-generation sequencing demonstrates that the genetic landscape of SCLC. Mutation status of LRP1B, MAP3K13, MSH6 and SPEN has prognostic significance, which might be potential therapeutic targets. We found possible genes and related signaling pathways that affect metastasis. These results can improve our understanding of the mutation characteristics of SCLC and identify potential biomarkers to guide targeted therapies.

Modulation of RNA splicing associated with Wnt signaling pathway using FD-895 and pladienolide B

Alterations in RNA splicing are associated with different malignancies, including leukemia, lymphoma, and solid tumors. The RNA splicing modulators such as FD-895 and pladienolide B have been investigated in different malignancies to target/modulate spliceosome for therapeutic purpose. Different cell lines were screened using an RNA splicing modulator to test in vitro cytotoxicity and the ability to modulate RNA splicing capability via induction of intron retention (using RT-PCR and qPCR). The Cignal Finder Reporter Array evaluated [pathways affected by the splice modulators in HeLa cells. Further, the candidates associated with the pathways were validated at protein level using western blot assay, and gene-gene interaction studies were carried out using GeneMANIA. We show that FD-895 and pladienolide B induces higher apoptosis levels than conventional chemotherapy in different solid tumors. In addition, both agents modulate Wnt signaling pathways and mRNA splicing. Specifically, FD-895 and pladienolide B significantly downregulates Wnt signaling pathway-associated transcripts (GSK3β and LRP5) and both transcript and proteins including LEF1, CCND1, LRP6, and pLRP6 at the transcript, total protein, and protein phosphorylation's levels. These results indicate FD-895 and pladienolide B inhibit Wnt signaling by decreasing LRP6 phosphorylation and modulating mRNA splicing through induction of intron retention in solid tumors.

Identification of causative gene mutation in an Iranian family with coloboma and nephropathy using whole exome sequencing

Pathogenic variants in FAT1 gene have recently been described in association with coloboma, nephropathy, and facial dismorphism. Here we describe a 5-year-old Iranian boy with iris coloboma and nephropathy, born to an Iranian family. Extracted genomic DNA from blood sample was used to perform whole exome sequencing in the patient. The mutational screening revealed a homozygote Fat1 gene mutation c.5320A > G (p.17747Val), not previously reported in homozygote state in Iran. Our findings establish FAT1 as a gene with pleiotropic effects in human, emphasizing it as one of the causative genes in syndromic nephropathies.

At the Crossroads of Molecular Biology and Immunology: Molecular Pathways for Immunological Targeting of Head and Neck Squamous Cell Carcinoma

Background: Recent advances in immunotherapy for head and neck squamous cell carcinoma (HNSCC) have led to implementation of anti-programmed death receptor 1 (PD-1) immunotherapy to standard of care for recurrent/metastatic HNSCC. However, the majority of tumors do not respond to these therapies, indicating that these tumors are not immunogenic or other immunosuppressive mechanisms might be at play. Aim: Given their role in carcinogenesis as well as in immune modulation, we discuss the relation between the STAT3, PI3K/AKT/mTOR and Wnt signaling pathways to identify potential targets to empower the immune response against HNSCC. Results: We focused on three pathways. First, STAT3 is often overactivated in HNSCC and induces the secretion of immunosuppressive cytokines, thereby promoting recruitment of immune suppressive regulatory T cells and myeloid-derived suppressor cells to the tumor microenvironment (TME) while hampering the development of dendritic cells. Second, PI3K/AKT/mTOR mutational activation results in increased tumor proliferation but could also be important in HNSCC immune evasion due to the downregulation of components in the antigen-processing machinery. Third, canonical Wnt signaling is overactivated in >20% of HNSCC and could be an interesting pleotropic target since it is related to increased tumor cell proliferation and the development of an immunosuppressive HNSCC TME. Conclusion: The molecular pathology of HNSCC is complex and heterogeneous, varying between sites and disease etiology (i.e., HPV). The in HNSCC widely affected signaling pathways STAT3, PI3K/AKT/mTOR and Wnt are implicated in some of the very mechanisms underlying immune evasion of HNSCC, thereby representing promising targets to possibly facilitate immunotherapy response.

Comprehensive Analysis of the Effects of Genetic Ancestry and Genetic Characteristics on the Clinical Evolution of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC), a kind of malignant cancer, is associated with increasing morbidity and mortality. Patients with different genetic ancestries may respond differently to clinical treatment. The limited understanding of the influence of genetic ancestry and genetic characteristics on OSCC impedes the development of precision medicine. To provide a reference for clinical treatment, this study comprehensively analyzed multigenomic differences in OSCC patients with different genetic ancestries and their impact on prognosis. An analysis of data from OSCC patients with different genetic ancestries in The Cancer Genome Atlas (TCGA) showed that the overall survival (OS) of African (AFR) patients was lower than that of primarily European (EUR) patients, and differences were also observed in the tumor-stroma ratio (TSR) and tumor-infiltrating lymphocytes (TILs), which are associated with prognosis. FAT1 is a key mutant gene in OSCC, and it has inconsistent effects on clinical evolution for patients with diverse genetic characteristics. PIKfyve and CAPN9 showed a significant difference in mutation frequency between EUR and AFR; PIKfyve was related to Ki-67 expression, suggesting that it could promote tumor proliferation, and CAPN9 was related to the expression of Bcl-2, promoting tumor cell apoptosis. A variant methylation locus, cg20469139, was correlated with the levels of PD-L1 and Caspase-7 and modulated tumor cell apoptosis. A novel ceRNA model was constructed based on genetic ancestries, and it could accurately evaluate patient prognosis. More importantly, although T cell dysfunction scores could determine the potential of tumor immune escape, the efficacy was obviously affected by patients' genetic ancestries. To provide patients with more precise, personalized therapy and to further improve their quality of life and 5-year survival rate, the influence of genetic ancestry should be fully considered when selecting treatments.

The Molecular Basis and Therapeutic Aspects of Cisplatin Resistance in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a kind of malignant tumors with low survival rate and prone to have early metastasis and recurrence. Cisplatin is an alkylating agent which induces DNA damage through the formation of cisplatin-DNA adducts, leading to cell cycle arrest and apoptosis. In the management of advanced OSCC, cisplatin-based chemotherapy or chemoradiotherapy has been considered as the first-line treatment. Unfortunately, only a portion of OSCC patients can benefit from cisplatin treatment, both inherent resistance and acquired resistance greatly limit the efficacy of cisplatin and even cause treatment failure. Herein, this review outline the underlying mechanisms of cisplatin resistance in OSCC from the aspects of DNA damage and repair, epigenetic regulation, transport processes, programmed cell death and tumor microenvironment. In addition, this review summarizes the strategies applicable to overcome cisplatin resistance, which can provide new ideas to improve the clinical therapeutic outcome of OSCC.

Fat1 suppresses the tumor-initiating ability of nonsmall cell lung cancer cells by promoting Yes-associated protein 1 nuclear-cytoplasmic translocation

The suppressive roles of Fat1 have been widely revealed in various tumors. However, its effects on the tumor-initiating ability of nonsmall cell lung cancer (NSCLC) cells have never been elucidated. Currently, we identified that a higher level of Fat1 mRNA expression predicted a longer overall survival and first-progression survival of lung cancer patients, especially in adenocarcinoma patients. In addition, Fat1 mRNA exhibited a lower level in lung cancer tissues relative to that in normal tissues. Functionally, we focused on the effects of Fat1 on the tumor-initiating ability of NSCLC cells and we found that Fat1 overexpression decreased the expression of tumor-initiating markers. Furthermore, overexpression of Fat1 reduced ALDH1 activity and sphere-formation ability of NSCLC cells. Mechanistically, we revealed that Fat1 promoted the nuclear-cytoplasmic transportation of YAP1 (Yes-associated protein 1), a critical executor of Hippo signaling, and a mutant form of YAP (YAP-5SA), which can escape from LATS1/2-mediated phosphorylation, rescued the Fat1-mediated inhibition on the tumor-initiating ability of NSCLC cells. This work prompts that Fat1 suppresses the tumor-initiating ability of NSCLC cells by activating Hippo signaling.

Drug resistance against 5-fluorouracil and cisplatin in the treatment of head and neck squamous cell carcinoma: A systematic review

Head and neck cancers are highly prevalent worldwide. Most of these lesions are diagnosed in the advanced stages of the disease. Thus, they do not often have a good long-term prognosis. Like other cancer types, head and neck cancers are managed by surgery, radiotherapy, and chemotherapy. Despite significant advances in the treatment of oral squamous cell carcinoma (OSCC), physicians encounter several challenges in the course of treatment. Various mechanisms mediate the clinical responses of a certain cancer to medications. Thus, efficient treatment planning requires adequate knowledge about the genes involved in drug resistance and the evaluation of the frequency percentage of resistance. Several studies have evaluated the causes and frequency percentages of 5-fluorouracil (5-FU) and cisplatin resistance. In this systematic review, all the relevant articles published until November 30, 2019, were retrieved from the Scopus, Embase, Medline, ISI, Web of Science, and Cochrane databases using certain MeSH and EMTTree keywords. A total of 2164 articles were retrieved of which, 18 were included in the review since they had reported the frequency percentages of drug resistance. Of all, 10 articles had evaluated cisplatin (1317 samples). A meta-analysis of the results revealed a frequency of 33% for cisplatin resistance. Eight studies had evaluated 5-FU (476 samples). A meta-analysis of the results revealed a frequency of 40.2 % for 5-FU resistance. Overcoming cisplatin resistance or 5-FU resistance can significantly enhance recovery in advanced HNSCC. Attempts should be made to eliminate the cause and use multi-drug regimens to increase the success rate of treatment.

Exploring the Mechanism of Scutellaria baicalensis Georgi Efficacy against Oral Squamous Cell Carcinoma Based on Network Pharmacology and Molecular Docking Analysis

BACKGROUND

Scutellaria baicalensis Georgi (SBG) has been widely shown to induce apoptosis and inhibit invasion and migration of various cancer cells. Increased evidence shows that SBG may be useful to treat oral squamous cell carcinoma (OSCC). However, the biological activity and possible mechanisms of SBG in the treatment of OSCC have not been fully elucidated. This study aimed to clarify the bioactive component and multitarget mechanisms of SBG against OSCC using network pharmacology and molecular docking.

METHODS

Traditional Chinese Medicine Systems Pharmacology (TCMSP) database was used to predict the active components in SBG, and putative molecular targets of SBG were identified using the Swiss Target Prediction database. OSCC-related targets were screened by GeneCards, Online Mendelian Inheritance in Man (OMIM), and Therapeutic Target Database (TTD). Then, we established protein-protein interaction (PPI), compound-target-disease (C-T-D), and compound-target-pathway (C-T-P) networks by Cytoscape to identify the main components, core targets, and pharmacological pathways of SBG against OSCC via applying data mining techniques and topological parameters. Metascape database was utilized for Gene Ontology (GO) and pathway enrichment analysis. The potential interaction of the main components with core targets was revealed by molecular docking simulation, and for the correlation between core targets and OSCC prognosis analysis, the Kaplan-Meier Plotter online database was used.

RESULTS

There were 25 active compounds in SBG and 86 genes targeted by OSCC. A total of 141 signaling pathways were identified, and it was found that the PI3K-Akt signaling pathway may occupy core status in the anti-OSCC system. GO analysis revealed that the primary biological processes were related to apoptosis, proliferation, and migration. Molecular docking results confirmed that core targets of OSCC had a high affinity with the main compounds of SBG.

CONCLUSION

Our study demonstrated multicomponent, multitarget, and multipathway characteristics of SBG in the treatment of OSCC and provided a foundation for further drug development research.

Major Molecular Signaling Pathways in Oral Cancer Associated With Therapeutic Resistance

Oral cancer is a sub-category of head and neck cancers that primarily initiates in the oral cavity. The primary treatment option for oral cancer remains surgery but it is associated with massive disfigurement, inability to carry out normal oral functions, psycho-social stress and exhaustive rehabilitation. Other treatment options such as chemotherapy and radiotherapy have their own limitations in terms of toxicity, intolerance and therapeutic resistance. Immunological treatments to enhance the body's ability to recognize cancer tissue as a foreign entity are also being used but they are new and underdeveloped. Although substantial progress has been made in the treatment of oral cancer, its complex heterogeneous nature still needs to be explored, to elucidate the molecular basis for developing resistance to therapeutic agents and how to overcome it, with the aim of improving the chances of patients' survival and their quality of life. This review provides an overview of up-to-date information on the complex role of the major molecules and associated signaling, epigenetic changes, DNA damage repair systems, cancer stem cells and micro RNAs in the development of therapeutic resistance and treatment failure in oral cancer. We have also summarized the current strategies being developed to overcome these therapeutic challenges. This review will help not only researchers but also oral oncologists in the management of the disease and in developing new therapeutic modalities.

Identification of the atypical cadherin FAT1 as a novel glypican-3 interacting protein in liver cancer cells

Glypican-3 (GPC3) is a cell surface heparan sulfate proteoglycan that is being evaluated as an emerging therapeutic target in hepatocellular carcinoma (HCC). GPC3 has been shown to interact with several extracellular signaling molecules, including Wnt, HGF, and Hedgehog. Here, we reported a cell surface transmembrane protein (FAT1) as a new GPC3 interacting protein. The GPC3 binding region on FAT1 was initially mapped to the C-terminal region (Q14517, residues 3662-4181), which covered a putative receptor tyrosine phosphatase (RTP)-like domain, a Laminin G-like domain, and five EGF-like domains. Fine mapping by ELISA and flow cytometry showed that the last four EGF-like domains (residues 4013-4181) contained a specific GPC3 binding site, whereas the RTP domain (residues 3662-3788) and the downstream Laminin G-2nd EGF-like region (residues 3829-4050) had non-specific GPC3 binding. In support of their interaction, GPC3 and FAT1 behaved concomitantly or at a similar pattern, e.g. having elevated expression in HCC cells, being up-regulated under hypoxia conditions, and being able to regulate the expression of EMT-related genes Snail, Vimentin, and E-Cadherin and promoting HCC cell migration. Taken together, our study provides the initial evidence for the novel mechanism of GPC3 and FAT1 in promoting HCC cell migration.

A Metabolic Gene Signature to Predict Overall Survival in Head and Neck Squamous Cell Carcinoma

Background

Head and neck squamous cell carcinoma (HNSCC) is a common malignancy that emanates from the lips, mouth, paranasal sinuses, oropharynx, larynx, nasopharynx, and from other pharyngeal cancers. The availability of high-throughput expression data has made it possible to use global gene expression data to analyze the relationship between metabolic-related gene expression and clinical outcomes in HNSCC patients.

Method

In this study, we used RNA sequencing (RNA-seq) data from the cancer genome atlas (TCGA), with validation in the GEO dataset to profile the metabolic microenvironment and define potential biomarkers for metabolic therapy.

Results

We extracted data for 529 patients and 327 metabolic genes (198 upregulated and 129 downregulated genes) in the TCGA database. Carbonic anhydrase 9 (CA9) and CA6 had the largest logFCs in the upregulated and downregulated genes, respectively. Our Cox regression model data showed 51 prognostic-related genes with lysocardiolipin acyltransferase 1 (LCLAT1) and choline dehydrogenase (CHDH) being associated with the highest risk (HR = 1.144, 95% CI = 1.044 ~ 1.251) and the lowest risk (HR = 0.580, 95% CI = 0.400 ~ 0.839) in HNSCC, respectively. We next used the ROC curve to evaluate whether the differentially expressed metabolic-related genes could serve as early predictors of HNSCC. The findings showed an AUC of 0.745 and 0.618 in the TCGA and GEO analysis, respectively. Besides, the ability for the genes to predict clinicopathological HNSCC status was analyzed and the data showed that the AUC for age, gender, grade, stage, T, M, and N was 0.520, 0.495, 0.568, 0.606, 0.577, 0.476, and 0.673, respectively, in the TCGA dataset. On the other hand, the AUC for age, gender, stage, T, M, N, smoking, and HPV16-pos was 0.599, 0.531, 0.622, 0.606, 0.616, 0.550, 0.614, 0.519, and 0.397, respectively, in the GEO dataset.

Conclusion

Taken together, our study unearths a novel metabolic gene signature for the prediction of HNSCC prognosis based on the TCGA dataset. Our signature might point out the metabolic microenvironment disorders and provides potential treatment targets and prognostic biomarkers.

Single-cell transcriptomics of human islet ontogeny defines the molecular basis of β-cell dedifferentiation in T2D

OBJECTIVE

Dedifferentiation of pancreatic β-cells may reduce islet function in type 2 diabetes (T2D). However, the prevalence, plasticity and functional consequences of this cellular state remain unknown.

METHODS

We employed single-cell RNAseq to detail the maturation program of α- and β-cells during human ontogeny. We also compared islets from non-diabetic and T2D individuals.

RESULTS

Both α- and β-cells mature in part by repressing non-endocrine genes; however, α-cells retain hallmarks of an immature state, while β-cells attain a full β-cell specific gene expression program. In islets from T2D donors, both α- and β-cells have a less mature expression profile, de-repressing the juvenile genetic program and exocrine genes and increasing expression of exocytosis, inflammation and stress response signalling pathways. These changes are consistent with the increased proportion of β-cells displaying suboptimal function observed in T2D islets.

CONCLUSIONS

These findings provide new insights into the molecular program underlying islet cell maturation during human ontogeny and the loss of transcriptomic maturity that occurs in islets of type 2 diabetics.

WNT7A Promotes EGF-Induced Migration of Oral Squamous Cell Carcinoma Cells by Activating β-Catenin/MMP9-Mediated Signaling

Aims and hypothesis

Epidermal growth factor (EGF) has been shown to induce the migration of various cancer cells. However, the underlying signaling mechanisms for EGF-induced migration of oral squamous cell carcinoma (OSCC) remain to be elucidated. WNT7A, a member of the family of 19 Wnt secreted glycoproteins, is commonly associated with tumor development. It is mostly unknown whether and, if so, how EGF modulates WNT7A in OSCC cells. The role of WNT7A in OSCC was thus investigated to explore the underlying signaling mechanisms for EGF-induced migration of OSCC.

Methods

Cell migration was measured by Wound healing assay and Transwell assay. Western blotting was carried out to detect the expression of WNT7A, MMP9, β-catenin, p-AKT, and p-ERK. The cells were transfected with plasmids or siRNA to upregulate or downregulate the expression of WNT7A. The location of β-catenin was displayed by immunofluorescence microscopy. Immunohistochemistry was carried out to confirm the relation between WNT7A expression and OSCC progression.

Results

The present study showed that the levels of WNT7A mRNA and protein were increased by EGF stimulation in OSCC cells. Besides, it was proved that p-AKT, but not p-ERK, mediated the expression of WNT7A protein induced by EGF. Furthermore, the inhibition of AKT activation prevented the EGF-induced increase of WNT7A and matrix metallopeptidase 9 (MMP9) expression and translocation of β-catenin from the cytoplasm to the nucleus. Moreover, histological analysis of OSCC specimens revealed an association between WNT7A expression and poor clinical prognosis of the disease.

Conclusions

The data in this paper indicated that WNT7A could be a potential oncogene in OSCC and identified a novel PI3K/AKT/WNT7A/β-catenin/MMP9 signaling for EGF-induced migration of OSCC cells.