Deciphering the cells of origin of squamous cell carcinomas

Preclinical Models for the Study of Lung Cancer Pathogenesis and Therapy Development

Experimental preclinical models have been a cornerstone of lung cancer translational research. Work in these model systems has provided insights into the biology of lung cancer subtypes and their origins, contributed to our understanding of the mechanisms that underlie tumor progression, and revealed new therapeutic vulnerabilities. Initially patient-derived lung cancer cell lines were the main preclinical models available. The landscape is very different now with numerous preclinical models for research each with unique characteristics. These include genetically engineered mouse models (GEMMs), patient-derived xenografts (PDXs) and three-dimensional culture systems ("organoid" cultures). Here we review the development and applications of these models and describe their contributions to lung cancer research.

Deregulation of AKT-mTOR Signaling Contributes to Chemoradiation Resistance in Lung Squamous Cell Carcinoma

Lung squamous cell carcinoma (LUSC) accounts for one of three of non-small cell lung carcinoma (NSCLC) and 30% of LUSC patients present with locally advanced, unresectable/medically inoperable disease, who are commonly treated with definitive chemoradiation. However, disease relapse in the radiation fields occurs in one of three cases. We aim to explore the underlying molecular mechanisms of chemoradiation resistance of LUSC. Patient-derived xenograft (PDX) models of LUSC were established in immunodeficient mice, followed by treatment with cisplatin in combination with clinically relevant courses of ionizing radiation (20, 30, and 40 Gy). The recurrent tumors were extracted for functional proteomics using reverse phase protein analysis (RPPA). We found that phospho-AKT-S473, phospho-AKT-T308, phospho-S6-S235/6, and phospho-GSK3β-S9 were upregulated in the chemoradiation-resistant 20 Gy + cisplatin and 40 Gy + cisplatin tumors compared with those in the control tumors. Ingenuity pathway analysis of the RPPA data revealed that AKT-mTOR signaling was the most activated signaling pathway in the chemoradiation-resistant tumors. Similarly, elevated AKT-mTOR signaling was observed in stable 40 Gy and 60 Gy resistant HARA cell lines compared with the parental cell line. Accordingly, pharmacologic inhibition of mTOR kinase by Torin2 significantly sensitized LUSC cell lines to ionizing radiation. In conclusion, using chemoradiation-resistant PDX models coupled with RPPA proteomics analysis, we revealed that deregulation of AKT-mTOR signaling may contribute to the chemoradiation resistance of LUSC. IMPLICATIONS: Clonal selection of subpopulations with high AKT-mTOR signaling in heterogeneous tumors may contribute to relapse of LUSC after chemoradiation. mTOR kinase inhibitors may be promising radiosensitizing agents in upfront treatment to prevent acquired resistance.

Biological and clinical implications of metastasis-associated circular RNAs in oesophageal squamous cell carcinoma

Oesophageal squamous cell carcinoma (OSCC) is a prevalent malignancy with high morbidity and mortality as a result of early metastasis and poor prognosis. Metastasis is a multistep process, involving various signalling pathways. Circular RNAs (circRNAs) are a class of covalently closed noncoding RNAs, the aberrant expression of which is reported to be involved in several biological events, including cell transformation, proliferation, migration, invasion, apoptosis and metastasis. Several studies have reported interactions between circRNAs and metastasis-associated signalling pathways. The abundance, stability and highly specific expression of candidate circRNAs make them potential biomarkers and therapeutic targets in OSCC. In this review article, we comprehensively describe metastasis-related circRNAs and their interactions with epithelial-mesenchymal transition-associated molecules. We also describe the molecular mechanisms and clinical relevance of circRNAs in OSCC progression and metastasis.

NR2F2 controls malignant squamous cell carcinoma state by promoting stemness and invasion and repressing differentiation

The nongenetic mechanisms required to sustain malignant tumor state are poorly understood. During the transition from benign tumors to malignant carcinoma, tumor cells need to repress differentiation and acquire invasive features. Using transcriptional profiling of cancer stem cells from benign tumors and malignant skin squamous cell carcinoma (SCC), we identified the nuclear receptor NR2F2 as uniquely expressed in malignant SCC. Using genetic gain of function and loss of function in vivo, we show that NR2F2 is essential for promoting the malignant tumor state by controlling tumor stemness and maintenance in mouse and human SCC. We demonstrate that NR2F2 promotes tumor cell proliferation, epithelial-mesenchymal transition and invasive features, while repressing tumor differentiation and immune cell infiltration by regulating a common transcriptional program in mouse and human SCCs. Altogether, we identify NR2F2 as a key regulator of malignant cancer stem cell functions that promotes tumor renewal and restricts differentiation to sustain a malignant tumor state.

Carcinoma of unknown primary origin with isolated adrenal metastasis: a report of two cases

The adrenal glands are one of the most common sites of malignant tumor metastasis. However, metastatic adrenal carcinoma of unknown primary origin with localized adrenal gland involvement is an extremely rare condition. Herein, we reported two cases of carcinoma of unknown primary origin with isolated adrenal metastasis. In the first case, back pain was the trigger; while in the second case, the triggers were low fever and weight loss. Metabolic abnormalities such as hypertension and obesity were not detected in either case. Neither patient had relevant previous medical histories, including malignancy. However, both had a long-term history of smoking. Systemic imaging studies revealed only adrenal tumors and surrounding lesions. Primary adrenocortical carcinoma was initially suspected, and chemotherapy including mitotane was considered. However, due to difficulty in complete resection of the tumor, core needle tumor biopsies were performed. Histopathological examination of biopsy specimens led to the diagnosis of carcinoma of unknown primary origin with isolated adrenal metastasis. In both cases, additional laboratory testing showed high levels of serum squamous cell carcinoma-related antigen and serum cytokeratin fragment. Malignant lesions confined to the adrenal glands are rare. As in our cases, it could be occasionally difficult to differentiate non-functioning primary adrenocortical carcinoma from metastatic adrenal carcinoma of unknown primary origin localized to the adrenal gland. If the lesion is unresectable and there are elevated levels of several tumor markers with no apparent hormonal excess, core needle tumor biopsy should be considered to differentiate the primary tumor from the metastatic tumor.

Transcriptomic Correlates of Immunologic Activation in Head and Neck and Cervical Cancer

Targeting the immune system has emerged as an effective therapeutic strategy for the treatment of various tumor types, including Head and Neck Squamous Cell Carcinoma (HNSCC) and Non-small-Cell Lung Cancer (NSCLC), and checkpoint inhibitors have shown to improve patient survival in these tumor types. Unfortunately, not all cancers respond to these agents, making it necessary to identify responsive tumors. Several biomarkers of response have been described and clinically tested. As of yet what seems to be clear is that a pre-activation state of the immune system is necessary for these agents to be efficient. In this study, using established transcriptomic signatures, we identified a group of gene combination associated with favorable outcome in HNSCC linked to a higher presence of immune effector cells. CD2, CD3D, CD3E, and CXCR6 combined gene expression is associated with improved outcome of HNSCC patients and an increase of infiltrating immune effector cells. This new signature also identifies a subset of cervical squamous cell carcinoma (CSCC) patients with favorable prognosis, who show an increased presence of immune effector cells in the tumor, which outcome shows similarities with the HP-positive HNSCC cohort of patients. In addition, CD2, CD3D, CD3E, and CXCR6 signature is able to predict the best favorable prognosis in terms of overall survival of CSSC patients. Of note, these findings were not reproduced in other squamous cell carcinomas like esophageal SCC or lung SCC. Prospective confirmatory studies should be employed to validate these findings.

BRD4 REGULATES TRANSCRIPTION FACTOR ∆Np63αTO DRIVE A CANCER STEM CELL PHENOTYPE IN SQUAMOUS CELL CARCINOMAS

Bromodomain containing protein 4 (BRD4) plays a critical role in controlling the expression of genes involved in development and cancer. Inactivation of BRD4 inhibits cancer growth, making it a promising anticancer drug target. The cancer stem cell population is a key driver of recurrence and metastasis in cancer patients. Here we show that cancer stem-like cells can be enriched from squamous cell carcinomas, and that these cells display an aggressive phenotype with enhanced stem cell marker expression, migration, invasion, and tumor growth. BRD4 was highly elevated in this aggressive subpopulation of cells, and its function is critical for these cancer stem cell-like properties. Moreover, BRD4 regulated ∆Np63α, a key transcription factor that is essential for epithelial stem cell function that is often overexpressed in cancers. BRD4 regulated an EZH2/STAT3 complex that led to increased ∆Np63α-mediated transcription. Targeting BRD4 in human squamous cell carcinoma reduces ∆Np63α, leading to inhibition of spheroid formation, migration, invasion and tumor growth. These studies identify a novel BRD4-regulated signaling network in a subpopulation of cancer stem-like cells elucidating a possible avenue for effective therapeutic intervention.

Diagnostic and Prognostic Value of MicroRNAs in Metastasis and Recurrence of Head and Neck Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

MicroRNAs have been proven to make remarkable differences in the clinical behaviors of head and neck squamous cell carcinoma (HNSCC). This study aims to systematically analyze whether differential expression levels of microRNAs are related to recurrence or metastasis in patients with HNSCC. A comprehensive search of the PubMed, EMBASE, and CENTRAL was conducted up to July 24^th, 2021. Data were collected and combined from studies reporting recurrence-free survival (RFS) of HNSCC patients with high microRNA expression compared to those with low expression. Besides, studies providing necessary data for evaluating the diagnostic value of microRNAs for detecting recurrence and metastasis based on their expression levels were also included and combined. The pooled hazard ratio (HR) value for the outcomes of RFS in 1,093 HNSCC samples from 10 studies was 2.51 (95%CI: 2.13–2.96). A sensitivity of 0.79 (95% CI: 0.72–0.85) and specificity of 0.77 (95%CI: 0.68–0.83) were observed in three studies, of which 93 patients with recurrence and 82 nonrecurrence controls were included, and the area under the curve (AUC) was 0.85 (95% CI: 0.81–0.88). Additionally, high diagnostic accuracy of microRNAs in detecting lymph node metastasis (LNM) was also reported. In conclusion, two panels of microRNAs showed the potential to predict recurrence or diagnose recurrence in HNSCC patients, respectively, which could facilitate prognosis prediction and diagnosis of clinical behaviors in HNSCC patients.

MicroRNA31 and MMP-1 contribute to the differentiated pathway of invasion -with enhanced epithelial-to-mesenchymal transition- in squamous cell carcinoma of the skin

Epithelial to mesenchymal transition (EMT) is an important mechanism of invasion in cutaneous squamous cell carcinomas (cSCCs) and has been found to be enhanced in tumors originated from actinic keratosis with transformation limited to the basal epithelial layer -differentiated pathway-, compared to cases with invasion subsequent to complete epidermal transformation -classical pathway-. Several microRNAs and proteins can contribute to EMT modulation in cSCCs. MicroRNA21 and microRNA31 are involved in posttranscriptional regulation of protein expression and could play a relevant role in EMT and cSCC progression. Throughout the EMT process upregulation of matrix metalloproteinases (MMPs) enhances invasiveness and MMP-1 and MMP-3 contribute to local invasion, angiogenesis and metastasis in cSCCs. Additionally, cSCC development is associated with PTEN loss and NF-κB, NOTCH-1 and p63 activation. The aim of this work is to identify differences in the expression of those molecules between both pathways of cSCCs development. Eight tissue microarrays from 80 consecutive cSCCs were analyzed using LNA-based miRNA in situ hybridization for miRNA21 and miRNA31 evaluation, and immunohistochemistry for MMP-1, MMP-3, PTEN, NOTCH-1, NF-κB, p63 and CD31. Significantly higher expression of miRNA31 (p < 0.0001) and MMP-1 (p = 0.0072) and angiogenesis (p = 0.0199) were found in the differentiated pathway, whereas PTEN loss (p = 0.0430) was more marked in the classical pathway. No significant differences were found for the other markers. Our findings support a contribution of miRNA31 and MMP-1 in the differentiated pathway, associated to EMT and increased microvascularization. The greater PTEN loss in the classical pathway indicate that its relevance in cSCC is not EMT-related.

USP28: Oncogene or Tumor Suppressor? A Unifying Paradigm for Squamous Cell Carcinoma

Squamous cell carcinomas are therapeutically challenging tumor entities. Low response rates to radiotherapy and chemotherapy are commonly observed in squamous patients and, accordingly, the mortality rate is relatively high compared to other tumor entities. Recently, targeting USP28 has been emerged as a potential alternative to improve the therapeutic response and clinical outcomes of squamous patients. USP28 is a catalytically active deubiquitinase that governs a plethora of biological processes, including cellular proliferation, DNA damage repair, apoptosis and oncogenesis. In squamous cell carcinoma, USP28 is strongly expressed and stabilizes the essential squamous transcription factor ΔNp63, together with important oncogenic factors, such as NOTCH1, c-MYC and c-JUN. It is presumed that USP28 is an oncoprotein; however, recent data suggest that the deubiquitinase also has an antineoplastic effect regulating important tumor suppressor proteins, such as p53 and CHK2. In this review, we discuss: (1) The emerging role of USP28 in cancer. (2) The complexity and mutational landscape of squamous tumors. (3) The genetic alterations and cellular pathways that determine the function of USP28 in squamous cancer. (4) The development and current state of novel USP28 inhibitors.

Supervised Autonomous Electrosurgery for Soft Tissue Resection

Surgical resection is the current clinical standard of care for treating squamous cell carcinoma. Maintaining an adequate tumor resection margin is the key to a good surgical outcome, but tumor edge delineation errors are inevitable with manual surgery due to difficulty in visualization and hand-eye coordination. Surgical automation is a growing field of robotics to relieve surgeon burdens and to achieve a consistent and potentially better surgical outcome. This paper reports a novel robotic supervised autonomous electrosurgery technique for soft tissue resection achieving millimeter accuracy. The tumor resection procedure is decomposed to the subtask level for a more direct understanding and automation. A 4-DOF suction system is developed, and integrated with a 6-DOF electrocautery robot to perform resection experiments. A novel near-infrared fluorescent marker is manually dispensed on cadaver samples to define a pseudotumor, and intraoperatively tracked using a dual-camera system. The autonomous dual-robot resection cooperation workflow is proposed and evaluated in this study. The integrated system achieves autonomous localization of the pseudotumor by tracking the near-infrared marker, and performs supervised autonomous resection in cadaver porcine tongues (N=3). The three pseudotumors were successfully removed from porcine samples. The evaluated average surface and depth resection errors are 1.19 and 1.83mm, respectively. This work is an essential step towards autonomous tumor resections.

PHLDA3 is an important downstream mediator of p53 in squamous cell carcinogenesis

Squamous cell carcinomas (SCCs) are one of the most frequent solid cancer types in humans and are derived from stratified epithelial cells found in various organs. SCCs derived from various organs share common important properties including genomic abnormalities in the tumor suppressor gene p53. There is a carcinogen-induced mouse model of SCC which produces benign papilloma, some of which progress to advanced carcinoma and metastatic SCCs. These SCCs undergo key genetic alterations that are conserved between human and mice, including alterations in the genomic p53 sequence, and is therefore an ideal system to study the mechanisms of SCC tumorigenesis. Using this SCC model, we show that the PHLDA3 gene, a p53 target gene encoding an Akt repressor, is involved in the suppression of benign and metastatic tumor development. Loss of PHLDA3 induces an epithelial-mesenchymal transition (EMT) and can complement p53 loss in the formation of metastatic tumors. We also show that in human SCC patients, low PHLDA3 expression is associated with poorer prognosis. Collectively, this study identifies PHLDA3 as an important downstream molecule of p53 involved in SCC development and progression.

Regulation of tissue architecture and stem cell dynamics to sustain homeostasis and repair in the skin epidermis

Stratified epithelia are made up of several layers of cells, which act as a protective barrier for the organ they cover. To ensure their shielding effect, epithelia are naturally able to cope with constant environmental insults. This ability is enabled by their morphology and architecture, as well as the continuous turnover of stem and progenitor cells that constitute their building blocks. Stem cell fate decisions and dynamics are fundamental key biological processes that allow epithelia to exert their functions. By focusing on the skin epidermis, this review discusses how tissue architecture is generated during development, maintained through adult life, and re-established during regeneration.

Cystatin-B Negatively Regulates the Malignant Characteristics of Oral Squamous Cell Carcinoma Possibly Via the Epithelium Proliferation/Differentiation Program

Disturbance in the proteolytic process is one of the malignant signs of tumors. Proteolysis is highly orchestrated by cysteine cathepsin and its inhibitors. Cystatin-B (CSTB) is a general cysteine cathepsin inhibitor that prevents cysteine cathepsin from leaking from lysosomes and causing inappropriate proteolysis. Our study found that CSTB was downregulated in both oral squamous cell carcinoma (OSCC) tissues and cells compared with normal controls. Immunohistochemical analysis showed that CSTB was mainly distributed in the epithelial structure of OSCC tissues, and its expression intensity was related to the grade classification. A correlation analysis between CSTB and clinical prognosis was performed using gene expression data and clinical information acquired from The Cancer Genome Atlas (TCGA) database. Patients with lower expression levels of CSTB had shorter disease-free survival times and poorer clinicopathological features (e.g., lymph node metastases, perineural invasion, low degree of differentiation, and advanced tumor stage). OSCC cell models overexpressing CSTB were constructed to assess the effects of CSTB on malignant biological behaviors and upregulation of CSTB inhibited cell proliferation, migration, and invasion in vitro. Weighted gene correlation network analysis (WGCNA) and gene set enrichment analysis (GSEA) were performed based on the TCGA data to explore potential mechanisms, and CSTB appeared to correlate with squamous epithelial proliferation-differentiation processes, such as epidermal cell differentiation and keratinization. Moreover, in WGCNA, the gene module most associated with CSTB expression (i.e., the brown module) was also the one most associated with grade classification. Upregulation of CSTB promoted the expression levels of markers (LOR, IVL, KRT5/14, and KRT1/10), reflecting a tendency for differentiation and keratinization in vitro. Gene expression profile data of the overexpressed CSTB cell line were obtained by RNA sequencing (RNA-seq) technology. By comparing the GSEA enrichment results of RNA-seq data (from the OSCC models overexpressing CSTB) and existing public database data, three gene sets (i.e., apical junction, G2/M checkpoint, etc.) and six pathways (e.g., NOTCH signaling pathway, glycosaminoglycan degradation, mismatch repair, etc.) were enriched in the data from both sources. Overall, our study shows that CSTB is downregulated in OSCC and might regulate the malignant characteristics of OSCC via the epithelial proliferation/differentiation program.

Skin Cancers and the Contribution of Rho GTPase Signaling Networks to Their Progression

Skin cancers are the most common cancers worldwide. Among them, melanoma, basal cell carcinoma of the skin and cutaneous squamous cell carcinoma are the three major subtypes. These cancers are characterized by different genetic perturbations even though they are similarly caused by a lifelong exposure to the sun. The main oncogenic drivers of skin cancer initiation have been known for a while, yet it remains unclear what are the molecular events that mediate their oncogenic functions and that contribute to their progression. Moreover, patients with aggressive skin cancers have been known to develop resistance to currently available treatment, which is urging us to identify new therapeutic opportunities based on a better understanding of skin cancer biology. More recently, the contribution of cytoskeletal dynamics and Rho GTPase signaling networks to the progression of skin cancers has been highlighted by several studies. In this review, we underline the various perturbations in the activity and regulation of Rho GTPase network components that contribute to skin cancer development, and we explore the emerging therapeutic opportunities that are surfacing from these studies.

Activation of bivalent factor DLX5 cooperates with master regulator TP63 to promote squamous cell carcinoma

To reconstruct systematically hyperactive transcription factor (TF)-dependent transcription networks in squamous cell carcinomas (SCCs), a computational method (ELMER) was applied to 1293 pan-SCC patient samples, and 44 hyperactive SCC TFs were identified. As a top candidate, DLX5 exhibits a notable bifurcate re-configuration of its bivalent promoter in cancer. Specifically, DLX5 maintains a bivalent state in normal tissues; its promoter is hypermethylation, leading to DLX5 transcriptional silencing in esophageal adenocarcinoma (EAC). In stark contrast, DLX5 promoter gains active histone marks and becomes transcriptionally activated in ESCC, which is directly mediated by SOX2. Functionally, silencing of DLX5 substantially inhibits SCC viability both in vitro and in vivo. Mechanistically, DLX5 cooperates with TP63 in regulating ∼2000 enhancers and promoters, which converge on activating cancer-promoting pathways. Together, our data establish a novel and strong SCC-promoting factor and elucidate a new epigenomic mechanism - bifurcate chromatin re-configuration - during cancer development.

MCL1 inhibition enhances the efficacy of docetaxel against airway-derived squamous cell carcinoma cells

MCL1 is an anti-apoptotic BCL2 family member that is often overexpressed in various malignant tumors. However, few reports have described the role of MCL1 in squamous cell carcinoma (SqCC) derived from airways including the lung. In this study, we examined whether MCL1 could be a novel druggable target for airway-derived SqCC, for which effective molecular targeted drugs are unavailable. We searched the Kaplan-Meier Plotter database and found that high MCL1 mRNA expression was significantly associated with shorter survival in patients with lower airway (lung) or upper airway (head and neck) derived SqCC. We also explored the Expression Atlas database and learned that authentic lung SqCC cell lines expressing both TP63 and KRT5 mRNA were extremely sparse among the publicly available "lung SqCC cell lines", with an exception being HARA cells. HARA cells were highly dependent on MCL1 for survival, and MCL1-depleted cells were not able to grow, and even declined in number, upon docetaxel (DTX) exposure in vitro and in vivo. Similar in vitro experimental findings, including those in a 3D culture model, were also obtained using Detroit 562 pharyngeal SqCC cells. These findings suggested that combined treatment with MCL1 silencing plus DTX appears highly effective against airway-derived SqCC.

Beta-adrenergic pathway activation enhances aggressiveness and inhibits stemness in head and neck cancer

Chronic stress leads to the activation of the beta-adrenergic pathway. Its activation has been implicated in the progression of different types of cancer but its role on head and neck squamous cell carcinomas (HNSCCs) remains undefined. The aim of this study was to investigate the influence of the beta-adrenergic pathway activation in the progression of HNSCCs and offer a panel of potential treatments for patients with the active beta-adrenergic pathway. Five hundred and twenty TCGA patients with primary HNSCCs were divided in two groups: ADRB2low / SLC6A2low and ADRB2high / SLC6A2high. Differentially expressed genes (DEGs) were identified through differential expression analysis. The association of clinicopathological and genomic features between the groups was analyzed using a bioinformatic approach. Potential drugs for treatment of HNSCC were identified based on the DEGs. There was association between ADRB2 and SLC6A2 expressions with age, race, tumor site, histologic grade, perineural invasion, and HPV p16 status. It was identified 898 DEGs between the groups. High ADRB2/SLC6A2 expression stimulated HNSCC proliferation, adhesion, invasion, and angiogenesis. On the other hand, genes related to cell stemness were downregulated in patients with activation of the beta- adrenergic pathway. Finally, 56 FDA-approved antineoplastic and immunotherapeutic drugs were identified as potential targets for the personalized treatment.

The regional distribution of melanosomes in the epidermis affords a localized intensive photoprotection for basal keratinocyte stem cells

Human skin is a highly efficient self-renewing barrier that is critical to withstanding environmental insults. Undifferentiated keratinocyte stem cells reside in the basal layer of the epidermis and in hair follicles that continuously give rise to progenies ensuring epidermal turnover and renewal. Ultraviolet (UV) radiation is a proven cause of skin keratinocyte cancers, which preferentially occur at sun-exposed areas of the skin. Fortunately, melanocytes produce melanin that is packaged in specific organelles (termed melanosomes) that are then delivered to nearby keratinocytes, endowing the recipient cells with photoprotection. It has long been thought that melanosome transfer takes place stochastically from melanocytes to keratinocytes via an as-yet-unrecognized manner. However, recent studies have indicated that melanosomes are distributed regionally in the basal layer of the skin, affording localized intensive photoprotection for progenitor keratinocytes and stem cells that reside in the microenvironment of the basal epidermis. In this review, we summarize current knowledge about molecular and cellular mechanisms that are responsible for the selective transfer and exclusive degradation of melanosomes in the epidermis, emphasizing implications for skin carcinogenesis.

Cellular heterogeneity and microenvironmental control of skin cancer

Healthy tissues harbour a surprisingly high number of cells that carry well-known cancer-causing mutations without impacting their physiological function. In recent years, strong evidence accumulated that the immediate environment of mutant cells profoundly impact their prospect of malignant progression. In this review, focusing on the skin, we investigate potential key mechanisms that ensure tissue homeostasis despite the presence of mutant cells, as well as critical factors that may nudge the balance from homeostasis to tumour formation. Functional in vivo studies and single-cell transcriptome analyses have revealed a tremendous cellular heterogeneity and plasticity within epidermal (stem) cells and their respective niches, revealing for example wild-type epithelial cells, fibroblasts or immune-cell subsets as critical in preventing cancer formation and malignant progression. It's the same cells, however, that can drive carcinogenesis. Therefore, understanding the abundance and molecular variation of cell types in health and disease, and how they interact and modulate the local signalling environment will thus be key for new therapeutic avenues in our battle against cancer.

Comprehensive analysis of DNA damage repair in squamous cell carcinoma subtypes

AIMS

Defective components resulting from DNA damage and repair mechanisms have been found to be underlying causes that affect the development and progression of different types of cancers, including squamous cell carcinoma (SCC). A more detailed classification of SCC is necessary for better application of DNA damage repair therapies.

MATERIALS AND METHODS

We aimed to characterize the molecular profile of SCC by developing a classification system based on DNA damage repair gene expression profiles. An integrative analysis was performed using a metadata set of 1374 SCC human samples from the UCSC Genome Browser. We then analyzed genomic alterations and mutations, and genes-TF-microRNA regulatory relationships and conducted enrichment, survival, and immune infiltration analyses.

KEY FINDINGS

This study was conducted on a total of 1374 SCC patients and 402 DNA damage repair genes. Two subtypes were established using consensus clustering, with 1143 patients being of the Non DDR subtype and 231 patients being of the DDR subtype. MATH, mutation burden, and heterogeneity were significantly higher in Non-DDR subtype than in DDR subtype. Next, a total of 1081 differentially expressed genes and 21 microRNAs were identified between the two subtypes and a genes-TF-microRNA regulatory network was constructed. In addition, stromal score, immune score and ESTIMATE score were significantly lower for the Non-DDR subtype, while tumor purity was significantly lower for the DDR subtype. In addition, five pathways associated with DNA damage repair were all enriched in the DDR subtype.

SIGNIFICANCE

Our study established two subtypes of SCC based on DNA damage repair, which may help to predict prognosis and determine the most suitable treatment for SCC patients.

Neoantigen: A New Breakthrough in Tumor Immunotherapy

Cancer immunotherapy works by stimulating and strengthening the body’s anti-tumor immune response to eliminate cancer cells. Over the past few decades, immunotherapy has shown remarkable efficacy in the treatment of cancer, particularly the success of immune checkpoint blockade targeting CTLA-4, PD-1 and PDL1, which has led to a breakthrough in tumor immunotherapy. Tumor neoantigens, a new approach to tumor immunotherapy, include antigens produced by tumor viruses integrated into the genome and antigens produced by mutant proteins, which are abundantly expressed only in tumor cells and have strong immunogenicity and tumor heterogeneity. A growing number of studies have highlighted the relationship between neoantigens and T cells’ recognition of cancer cells. Vaccines developed against neoantigens are now being used in clinical trials in various solid tumors. In this review, we summarized the latest advances in the classification of immunotherapy and the process of classification, identification and synthesis of tumor-specific neoantigens, as well as their role in current cancer immunotherapy. Finally, the application prospects and existing problems of neoantigens were discussed.

Deiodinases and Cancer

Hormones are key drivers of cancer development, and alteration of the intratumoral concentration of thyroid hormone (TH) is a common feature of many human neoplasias. Besides the systemic control of TH levels, the expression and activity of deiodinases constitute a major mechanism for the cell-autonomous, prereceptoral control of TH action. The action of deiodinases ensures tight control of TH availability at intracellular level in a time- and tissue-specific manner, and alterations in deiodinase expression are frequent in tumors. Research over the past decades has shown that in cancer cells, a complex and dynamic expression of deiodinases is orchestrated by a network of growth factors, oncogenic proteins, and miRNA. It has become increasingly evident that this fine regulation exposes cancer cells to a dynamic concentration of TH that is functional to stimulate or inhibit various cellular functions. This review summarizes recent advances in the identification of the complex interplay between deiodinases and cancer and how this family of enzymes is relevant in cancer progression. We also discuss whether deiodinase expression could represent a diagnostic tool with which to define tumor staging in cancer treatment or even a therapeutic tool against cancer.

Recent advances in preclinical models for lung squamous cell carcinoma

Lung squamous cell carcinoma (LUSC) represents a major subtype of non-small cell lung cancer with limited treatment options. Previous studies have elucidated the complex genetic landscape of LUSC and revealed multiple altered genes and pathways. However, in stark contrast to lung adenocarcinoma, few targetable driver mutations have been established so far and targeted therapies for LUSC remain unsuccessful. Immunotherapy has revolutionized LUSC treatment and is currently approved as the new standard of care. To gain a better understanding of the LUSC biology, improved modeling systems are urgently needed. Preclinical models, particularly those mimicking human disease with an intact tumor immune microenvironment, are an invaluable tool to study cancer development and evaluate new therapeutic targets. Here, we discuss recent advances in LUSC preclinical models, with a focus on genetically engineered mouse models (GEMMs) and organoids, in the context of evolving precision medicine and immunotherapy.

Oxidative Stress and the Intersection of Oncogenic Signaling and Metabolism in Squamous Cell Carcinomas

Squamous cell carcinomas (SCCs) arise from both stratified squamous and non-squamous epithelium of diverse anatomical sites and collectively represent one of the most frequent solid tumors, accounting for more than one million cancer deaths annually. Despite this prevalence, SCC patients have not fully benefited from recent advances in molecularly targeted therapy or immunotherapy. Rather, decades old platinum-based or radiation regimens retaining limited specificity to the unique characteristics of SCC remain first-line treatment options. Historically, a lack of a consolidated perspective on genetic aberrations driving oncogenic transformation and other such factors essential for SCC pathogenesis and intrinsic confounding cellular heterogeneity in SCC have contributed to a critical dearth in effective and specific therapies. However, emerging evidence characterizing the distinct genomic, epigenetic, and metabolic landscapes of SCC may be elucidating unifying features in a seemingly heterogeneous disease. In this review, by describing distinct metabolic alterations and genetic drivers of SCC revealed by recent studies, we aim to establish a conceptual framework for a previously unappreciated network of oncogenic signaling, redox perturbation, and metabolic reprogramming that may reveal targetable vulnerabilities at their intersection.

Primary nonkeratinizing squamous cell carcinoma of the scapular bone: A case report

BACKGROUND

Squamous cell carcinoma (SCC) of bone is usually caused by metastasis from the lungs, bladder, or other sites. Primary SCC of bone most frequently involves the skull bones, and primary involvement of other sites in the skeletal system is extremely rare. To date, only three such cases have been reported, which makes the diagnosis, treatment, and prognosis of this disease a challenge.

CASE SUMMARY

A 76-year-old Chinese man presented to our hospital with nonspecific pain and limited mobility in the right shoulder for 4 mo. He underwent three-dimensional computed tomography reconstruction and magnetic resonance imaging of the right shoulder, which revealed an osteolytic destructive lesion in the right scapula with invasion into the surrounding muscles and soft tissues. Ultrasound-guided core needle biopsy detected a malignant tumor, and immunohistochemical analysis revealed a poorly differentiated SCC. Wide excision of the right scapular bone was performed, and pathological examination of the surgical specimen confirmed the diagnosis. At the last follow-up examination within 2 years, the patient was doing well with the pain significantly relieved in the right shoulder.

CONCLUSION

Primary SCC of bone is extremely rare at sites other than the skull. Clinicians must exhaust all available means for the diagnosis of primary SCC of the bone, so greater attention can be paid to its timely and effective management. Regular and adequate follow-up is essential to help rule out metastasis and judge the prognosis.

Anlotinib enhances the antitumor activity of radiofrequency ablation on lung squamous cell carcinoma

Anlotinib is a novel molecular targeted drug that has been approved for the treatment of lung adenocarcinoma. Currently these agents are rarely used in the treatment of lung squamous cell carcinoma (LSCC). Bronchoscope-guided radiofrequency ablation (RFA) is a new strategy proposed for the treatment of LSCC that is able to alleviate the obstruction of the respiratory tract caused by LSCC by direct destruction of the tumor tissues. The presence work aims to reveal whether Anlotinib could enhance the antitumor activity of RFA on LSCC cells. The results from real-time PCR (qPCR) confirmed overexpression of targets of anlotinib activity, including receptor tyrosine kinase or the MPAK/PI3K-AKT pathway kinases, in LSCC tissues. Treatment with anlotinib inhibited the survival, in vitro invasion, and migration of LSCC cells. Moreover, the antitumor effects of RFA were investigated using a rodent model of LSCC. The combination of RFA and anlotinib treatment enhanced the antitumor effect of RFA treatment. We propose a combinative strategy of RFA and anlotinib as a novel approach for successful management of LSCC.

Optical diagnosis of oral cavity lesions by label-free Raman spectroscopy

Oral squamous cell carcinoma (OSCC) is one of the most prevalent cancers and frequently preceded by non-malignant lesions. Using Shifted-Excitation Raman Difference Spectroscopy (SERDS), principal component and linear discriminant analysis in native tissue specimens, 9500 raw Raman spectra of OSCC, 4300 of non-malignant lesions and 4200 of physiological mucosa were evaluated. Non-malignant lesions were distinguished from physiological mucosa with a classification accuracy of 95.3% (95.4% sensitivity, 95.2% specificity, area under the curve (AUC) 0.99). Discriminating OSCC from non-malignant lesions showed an accuracy of 88.4% (93.7% sensitivity, 76.7% specificity, AUC 0.93). OSCC was identified against physiological mucosa with an accuracy of 89.8% (93.7% sensitivity, 81.0% specificity, AUC 0.90). These findings underline the potential of SERDS for the diagnosis of oral cavity lesions.

TRIM32/USP11 Balances ARID1A Stability and the Oncogenic/Tumor-Suppressive Status of Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) is an aggressive epithelial malignancy, yet the molecular mechanisms underlying SCC development are elusive. ARID1A is frequently mutated in various cancer types, but both mutation rates and expression levels of ARID1A are ubiquitously low in SCCs. Here, we reveal that excessive protein degradation mediated by the ubiquitin-proteasome system (UPS) contributes to the loss of ARID1A expression in SCC. We identify that the E3 ligase TRIM32 and the deubiquitinase USP11 play key roles in controlling ARID1A stability. TRIM32 depletion inhibits SCC cell proliferation, metastasis, and chemoresistance by stabilizing ARID1A, while USP11 depletion promotes SCC development by promoting ARID1A degradation. We show that syndecan-2 (SDC2) is the downstream target of both ARID1A and USP11 and that SDC2 depletion abolishes the oncogenic function of ARID1A loss. In summary, our data reveal UPS-mediated protein degradation as a mechanism underlying ARID1A loss and propose an important role for the TRIM32/USP11-ARID1A-SDC2 axis in SCC.

Fat1 deletion promotes hybrid EMT state, tumour stemness and metastasis

FAT1, which encodes a protocadherin, is one of the most frequently mutated genes in human cancers^1-5. However, the role and the molecular mechanisms by which FAT1 mutations control tumour initiation and progression are poorly understood. Here, using mouse models of skin squamous cell carcinoma and lung tumours, we found that deletion of Fat1 accelerates tumour initiation and malignant progression and promotes a hybrid epithelial-to-mesenchymal transition (EMT) phenotype. We also found this hybrid EMT state in FAT1-mutated human squamous cell carcinomas. Skin squamous cell carcinomas in which Fat1 was deleted presented increased tumour stemness and spontaneous metastasis. We performed transcriptional and chromatin profiling combined with proteomic analyses and mechanistic studies, which revealed that loss of function of FAT1 activates a CAMK2-CD44-SRC axis that promotes YAP1 nuclear translocation and ZEB1 expression that stimulates the mesenchymal state. This loss of function also inactivates EZH2, promoting SOX2 expression, which sustains the epithelial state. Our comprehensive analysis identified drug resistance and vulnerabilities in FAT1-deficient tumours, which have important implications for cancer therapy. Our studies reveal that, in mouse and human squamous cell carcinoma, loss of function of FAT1 promotes tumour initiation, progression, invasiveness, stemness and metastasis through the induction of a hybrid EMT state.

Identification of CHRNB4 as a Diagnostic/Prognostic Indicator and Therapeutic Target in Human Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive malignant tumors and there is a lack of biomarkers for ESCC diagnosis and prognosis. Family subunits of cholinergic nicotinic receptor genes (CHRNs) are involved in smoking behavior and tumor cell proliferation. Previous researches have shown similar molecular features and pathogenic mechanisms among ESCC, head and neck squamous cell carcinoma (HNSC), and lung squamous cell carcinoma (LUSC). Using edgeR, three mutual differentially expressed genes of CHRNs were found to be significantly upregulated at the mRNA level in ESCC, LUSC, and HNSC compared to matched normal tissues. Kaplan–Meier survival analysis showed that high expression of CHRNB4 was associated with unfavorable prognosis in ESCC and HNSC. The specific expression analysis revealed that CHRNB4 is highly expressed selectively in squamous cell carcinomas compared to adenocarcinoma. Cox proportional hazards regression analysis was performed to find that just the single gene CHRNB4 has enough independent prognostic ability, with the area under curve surpassing the tumor-node-metastasis (TNM) staging-based model, the most commonly used model in clinical application in ESCC. In addition, an effective prognostic nomogram was established combining the TNM stage, gender of patients, and expression of CHRNB4 for ESCC patients, revealing an excellent prognostic ability when compared to the model of CHRNB4 alone or TNM. Gene Set Enrichment Analysis results suggested that the expression of CHRNB4 was associated with cancer-related pathways, such as the mTOR pathway. Cell Counting Kit-8, cloning formation assay, and western blot proved that CHRNB4 knockdown can inhibit the proliferation of ESCC cells via the Akt/mTOR and ERK1/2/mTOR pathways, which might facilitate the prolonged survival of patients. Furthermore, we conducted structure-based molecular docking, and potential modulators against CHRNB4 were screened from FDA approved drugs. These findings suggested that CHRNB4 specifically expressed in SCCs, and may serve as a promising biomarker for diagnosis and prognosis prediction, and it can even become a therapeutic target of ESCC patients.

Immune Checkpoint Blockade in Advanced Cutaneous Squamous Cell Carcinoma: What Do We Currently Know in 2020?

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer that predominantly arises in chronically sun-damaged skin. Immunosuppression, genetic disorders such as xeroderma pigmentosum (XP), exposure to certain drugs and environmental noxae have been identified as major risk factors. Surgical removal of cSCC is the therapy of choice and mostly curative in early stages. However, a minority of patients develop locally advanced tumors or distant metastases that are still challenging to treat. Immune checkpoint blockade (ICB) targeting CTLA-4, PD-L1 and PD-1 has tremendously changed the field of oncological therapy and especially the treatment of skin cancers as tumors with a high mutational burden. In this review, we focus on the differences between cSCC and cutaneous melanoma (CM) and their implications on therapy, summarize the current evidence on ICB for the treatment of advanced cSCC and discuss the chances and pitfalls of this therapy option for this cancer entity. Furthermore, we focus on special subgroups of interest such as organ transplant recipients, patients with hematologic malignancies, XP and field cancerization.

Title- Genomic landscape of squamous cell carcinoma- Different genetic pathways culminating in a common phenotype

INTRODUCTION

Squamous cell carcinomas (SqCCs) are the most common solid tumors in humans and are found across multiple organ systems. Although, integrated analysis of genetic alterations divulge similarities between SqCCs from various body sites, certain genes appear to be more frequently mutated in a given SqCC. These subtle differences may hold the key to determining the differentiation characteristics and predicting aggressiveness of tumors.

MATERIALS AND METHOD

Fifty-four cases of SqCCs, in which the primary location of the tumor could be ascertained by clinical and radiological findings, were included in this study. Next generation sequencing data was analyzed for recurrent genetic abnormalities.

RESULTS

Genetic alterations were found in 219 genes in the 54 cases studied. TP53 mutations were found to be more frequent in pulmonary SqCCs (86.5%) as compared to non-pulmonary SqCCs (58.8%) (p<0.05). NOTCH gene family mutations and CREBBP mutations were limited to non-pulmonary SqCC (p<0.005) and were mutated in 41.2% and 17.6% cases.

CONCLUSION

A detailed comparative analysis of the genetic alterations identified by sequencing identified higher frequency of TP53 mutations in lung SqCCs as compared to non-pulmonary SqCCs. NOTCH and CREBPP mutations were found to be absent in lung and head and neck SqCCs and more frequent in SqCCs from other locations.

TP63 links chromatin remodeling and enhancer reprogramming to epidermal differentiation and squamous cell carcinoma development

Squamous cell carcinoma (SCC) is an aggressive malignancy that can originate from various organs. TP63 is a master regulator that plays an essential role in epidermal differentiation. It is also a lineage-dependent oncogene in SCC. ΔNp63α is the prominent isoform of TP63 expressed in epidermal cells and SCC, and overexpression promotes SCC development through a variety of mechanisms. Recently, ΔNp63α was highlighted to act as an epidermal-specific pioneer factor that binds closed chromatin and enhances chromatin accessibility at epidermal enhancers. ΔNp63α coordinates chromatin-remodeling enzymes to orchestrate the tissue-specific enhancer landscape and three-dimensional high-order architecture of chromatin. Moreover, ΔNp63α establishes squamous-like enhancer landscapes to drive oncogenic target expression during SCC development. Importantly, ΔNp63α acts as an upstream regulator of super enhancers to activate a number of oncogenic transcripts linked to poor prognosis in SCC. Mechanistically, ΔNp63α activates genes transcription through physically interacting with a number of epigenetic modulators to establish enhancers and enhance chromatin accessibility. In contrast, ΔNp63α also represses gene transcription via interacting with repressive epigenetic regulators. ΔNp63α expression is regulated at multiple levels, including transcriptional, post-transcriptional, and post-translational levels. In this review, we summarize recent advances of p63 in epigenomic and transcriptional control, as well as the mechanistic regulation of p63.

The cellular origins of cancer with particular reference to the gastrointestinal tract

Stem cells or their closely related committed progenitor cells are the likely founder cells of most neoplasms. In the continually renewing and hierarchically organized epithelia of the oesophagus, stomach and intestine, homeostatic stem cells are located at the beginning of the cell flux, in the basal layer of the oesophagus, the isthmic region of gastric oxyntic glands and at the bottom of gastric pyloric-antral glands and colonic crypts. The introduction of mutant oncogenes such as KrasG12D or loss of Tp53 or Apc to specific cell types expressing the likes of Lgr5 and Mist1 can be readily accomplished in genetically engineered mouse models to initiate tumorigenesis. Other origins of cancer are discussed including 'reserve' stem cells that may be activated by damage or through disruption of morphogen gradients along the crypt axis. In the liver and pancreas, with little cell turnover and no obvious stem cell markers, the importance of regenerative hyperplasia associated with chronic inflammation to tumour initiation is vividly apparent, though inflammatory conditions in the renewing populations are also permissive for tumour induction. In the liver, hepatocytes, biliary epithelial cells and hepatic progenitor cells are embryologically related, and all can give rise to hepatocellular carcinoma and cholangiocarcinoma. In the exocrine pancreas, both acinar and ductal cells can give rise to pancreatic ductal adenocarcinoma (PDAC), although the preceding preneoplastic states are quite different: acinar-ductal metaplasia gives rise to pancreatic intraepithelial neoplasia culminating in PDAC, while ducts give rise to PDAC via. mucinous cell metaplasia that may have a polyclonal origin.

Discovering New Progenitor Cell Populations through Lineage Tracing and In Vivo Imaging

Identification of progenitor cells that generate differentiated cell types during development, regeneration, and disease states is central to understanding the mechanisms governing such transitions. For more than a century, different lineage-tracing strategies have been developed, which helped disentangle the complex relationship between progenitor cells and their progenies. In this review, we discuss how lineage-tracing analyses have evolved alongside technological advances, and how this approach has contributed to the identification of progenitor cells in different contexts of cell differentiation. We also highlight a few examples in which lineage-tracing experiments have been instrumental for resolving long-standing debates and for identifying unexpected cellular origins. This discussion emphasizes how this century-old quest to delineate cellular lineage relationships is still active, and new discoveries are being made with the development of newer methodologies.

ARID1A Hypermethylation Disrupts Transcriptional Homeostasis to Promote Squamous Cell Carcinoma Progression

Switch/Sucrose Non-Fermentable (SWI/SNF) chromatin-remodeling complexes have a mutation rate of approximately 20% in human cancer, and ARID1A is the most frequently mutated component. However, some components of SWI/SNF complexes, including ARID1A, exhibit a very low mutation rate in squamous cell carcinoma (SCC), and their role in SCC remains unknown. Here, we demonstrate that the low expression of ARID1A in SCC is the result of promoter hypermethylation. Low levels of ARID1A were associated with a poor prognosis. ARID1A maintained transcriptional homeostasis through both direct and indirect chromatin-remodeling mechanisms. Depletion of ARID1A activated an oncogenic transcriptome that drove SCC progression. The anti-inflammatory natural product parthenolide was synthetically lethal to ARID1A-depleted SCC cells due to its inhibition of both HDAC1 and oncogenic signaling. These findings support the clinical application of parthenolide to treat patients with SCC with low ARID1A expression. SIGNIFICANCE: This study reveals novel inactivation mechanisms and tumor-suppressive roles of ARID1A in SCC and proposes parthenolide as an effective treatment for patients with SCC with low ARID1A expression.

Cancer Stem Cells-Origins and Biomarkers: Perspectives for Targeted Personalized Therapies

The use of biomarkers in diagnosis, therapy and prognosis has gained increasing interest over the last decades. In particular, the analysis of biomarkers in cancer patients within the pre- and post-therapeutic period is required to identify several types of cells, which carry a risk for a disease progression and subsequent post-therapeutic relapse. Cancer stem cells (CSCs) are a subpopulation of tumor cells that can drive tumor initiation and can cause relapses. At the time point of tumor initiation, CSCs originate from either differentiated cells or adult tissue resident stem cells. Due to their importance, several biomarkers that characterize CSCs have been identified and correlated to diagnosis, therapy and prognosis. However, CSCs have been shown to display a high plasticity, which changes their phenotypic and functional appearance. Such changes are induced by chemo- and radiotherapeutics as well as senescent tumor cells, which cause alterations in the tumor microenvironment. Induction of senescence causes tumor shrinkage by modulating an anti-tumorigenic environment in which tumor cells undergo growth arrest and immune cells are attracted. Besides these positive effects after therapy, senescence can also have negative effects displayed post-therapeutically. These unfavorable effects can directly promote cancer stemness by increasing CSC plasticity phenotypes, by activating stemness pathways in non-CSCs, as well as by promoting senescence escape and subsequent activation of stemness pathways. At the end, all these effects can lead to tumor relapse and metastasis. This review provides an overview of the most frequently used CSC markers and their implementation as biomarkers by focussing on deadliest solid (lung, stomach, liver, breast and colorectal cancers) and hematological (acute myeloid leukemia, chronic myeloid leukemia) cancers. Furthermore, it gives examples on how the CSC markers might be influenced by therapeutics, such as chemo- and radiotherapy, and the tumor microenvironment. It points out, that it is crucial to identify and monitor residual CSCs, senescent tumor cells, and the pro-tumorigenic senescence-associated secretory phenotype in a therapy follow-up using specific biomarkers. As a future perspective, a targeted immune-mediated strategy using chimeric antigen receptor based approaches for the removal of remaining chemotherapy-resistant cells as well as CSCs in a personalized therapeutic approach are discussed.

Integrin α3β1 in hair bulge stem cells modulates CCN2 expression and promotes skin tumorigenesis

Although hair bulge stem cells are not the cancer cells-of-origin, they contribute to two-stage DMBA/TPA skin carcinogenesis in an α3β1-dependent manner.

Epidermal-specific deletion of integrin α3β1 almost completely prevents the formation of papillomas during 7,12-Dimethylbenz[a]anthracene/12-O-tetradecanoylphorbol-13-acetate (DMBA/TPA) two-stage skin carcinogenesis. This dramatic decrease in tumorigenesis was thought to be due to an egress and premature differentiation of α3β1-depleted hair bulge (HB) stem cells (SCs), previously considered to be the cancer cells-of-origin in the DMBA/TPA model. Using a reporter mouse line with inducible deletion of α3β1 in HBs, we show that HB SCs remain confined to their niche regardless of the presence of α3β1 and are largely absent from skin tumors. However, tumor formation was significantly decreased in mice deficient for α3β1 in HB SCs. RNA sequencing of HB SCs isolated from short-term DMBA/TPA–treated skin showed α3β1-dependent expression of the matricellular protein connective tissue growth factor (CCN2), which was confirmed in vitro, where CCN2 promoted colony formation and 3D growth of transformed keratinocytes. Together, these findings show that HBs contribute to skin tumorigenesis in an α3β1-dependent manner and suggest a role of HB SCs in creating a permissive environment for tumor growth through the modulation of CCN2 secretion.

Oncogenic ALK F1174L drives tumorigenesis in cutaneous squamous cell carcinoma

Here, we show for the first time that anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase of the insulin receptor superfamily, plays a pivotal role in the pathogenesis of cSCC.

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer characterized by increased mortality. Here, we show for the first time that anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase of the insulin receptor superfamily, plays a pivotal role in the pathogenesis of cSCC. Our data demonstrate that the overexpression of the constitutively active, mutated ALK, ALK^F1174L, is sufficient to initiate the development of cSCC and is 100% penetrant. Moreover, we show that cSCC development upon ALK^F1174L overexpression is independent of the cell-of-origin. Molecularly, our data demonstrate that ALK^F1174L cooperates with oncogenic Kras^G12D and loss of p53, well-established events in the biology of cSCC. This cooperation results in a more aggressive cSCC type associated with a higher grade histological morphology. Finally, we demonstrate that Stat3 is a key downstream effector of ALK^F1174L and likely plays a role in ALK^F1174L-driven cSCC tumorigenesis. In sum, these findings reveal that ALK can exert its tumorigenic potential via cooperation with multiple pathways crucial in the pathogenesis of cSCC. Finally, we show that human cSCCs contain mutations in the ALK gene. Taken together, our data identify ALK as a new key player in the pathogenesis of cSCC, and this knowledge suggests that oncogenic ALK signaling can be a target for future clinical trials.

Lineage Decision-Making within Normal Haematopoietic and Leukemic Stem Cells

To produce the wide range of blood and immune cell types, haematopoietic stem cells can “choose” directly from the entire spectrum of blood cell fate-options. Affiliation to a single cell lineage can occur at the level of the haematopoietic stem cell and these cells are therefore a mixture of some pluripotent cells and many cells with lineage signatures. Even so, haematopoietic stem cells and their progeny that have chosen a particular fate can still “change their mind” and adopt a different developmental pathway. Many of the leukaemias arise in haematopoietic stem cells with the bulk of the often partially differentiated leukaemia cells belonging to just one cell type. We argue that the reason for this is that an oncogenic insult to the genome “hard wires” leukaemia stem cells, either through development or at some stage, to one cell lineage. Unlike normal haematopoietic stem cells, oncogene-transformed leukaemia stem cells and their progeny are unable to adopt an alternative pathway.

Enhanced DNA-repair capacity and resistance to chemically induced carcinogenesis upon deletion of the phosphatase regulator NIPP1

Nuclear Inhibitor of PP1 (NIPP1) is a conserved regulatory subunit of protein phosphatase PP1. The selective deletion of NIPP1 in mouse liver parenchymal cells or skin epidermal cells culminates in a late-onset hyperproliferation of a subset of resident progenitor cells. Although a hyperplastic phenotype is usually tumor promoting, we show here that the absence of NIPP1 conferred a strong resistance to chemically induced hepatocellular or skin carcinoma. The ablation of NIPP1 did not affect the metabolism of the administered mutagens (diethylnitrosamine or 7,12-dimethylbenz[a]anthracene), but reduced the conversion of mutagen-induced covalent DNA modifications into cancer-initiating mutations. This reduced sensitivity to mutagens correlated with an enhanced DNA-damage response and an augmented expression of rate-limiting DNA-repair proteins (MGMT in liver, XPD and XPG in skin), hinting at an increased DNA-repair capacity. Our data identify NIPP1 as a repressor of DNA repair and as a promising target for novel cancer prevention and treatment therapies.

Anlotinib is effective in patients with advanced oral cancer?

Oral cancer patients with recurrence or distant metastasis often present poor prognosis. Majority of advanced oral cancer patients suffer from treat-related adverse events and drug resistance. For those patients, the survival time and quality of life are urgent to be improved. Anlotinib, as a multi-targets tyrosine kinase inhibitor (TKI), has been demonstrated to be effective in many refractory tumors by inhibiting tumor angiogenesis and partial functions of tumor cells. In this paper, we performed CCK-8 assay, wound healing assay and transwell assay to explore the effect of anlotinib on human tongue squamous carcinoma Tca8113 cell line. Preliminary data indicated that anlotinib significantly inhibited Tca8113 cells proliferation, migration and invasion in vitro. Together, we proposed a hypothesis that anlotinib might be effective in prolonging survival time of patients with advanced oral cancer.

New models of large-cell neuroendocrine carcinoma and small-cell lung carcinoma

High-grade neuroendocrine lung carcinomas (LCNEC, SCLC) are recalcitrant cancers for which no optimal management has been achieved. We have recently described two models of LCNEC and SCLC developed upon inactivation of 4 tumor suppressors genes (Rb1 (RB transcriptional corepressor 1), Rbl1 (RB transcriptional corepressor like 1), Pten (phosphatase and tensin homolog), Trp53 (transformation-related protein 53), which provide a suitable frame for preclinical intervention. A defined model for LCNEC had not been previously reported.

Are Leukaemic Stem Cells Restricted to a Single Cell Lineage?

Cancer-stem-cell theory states that most, if not all, cancers arise from a stem/uncommitted cell. This theory revolutionised our view to reflect that cancer consists of a hierarchy of cells that mimic normal cell development. Elegant studies of twins who both developed acute lymphoblastic leukaemia in childhood revealed that at least two genomic insults are required for cancer to develop. These ‘hits’ do not appear to confer a growth advantage to cancer cells, nor do cancer cells appear to be better equipped to survive than normal cells. Cancer cells created by investigators by introducing specific genomic insults generally belong to one cell lineage. For example, transgenic mice in which the LIM-only 2 (LMO2, associated with human acute T-lymphoblastic leukaemia) and BCR-ABL^p210 (associated with human chronic myeloid leukaemia) oncogenes were active solely within the haematopoietic stem-cell compartment developed T-lymphocyte and neutrophil lineage-restricted leukaemia, respectively. This recapitulated the human form of these diseases. This ‘hardwiring’ of lineage affiliation, either throughout leukaemic stem cell development or at a particular stage, is different to the behaviour of normal haematopoietic stem cells. While normal cells directly commit to a developmental pathway, they also remain versatile and can develop into a terminally differentiated cell that is not part of the initial lineage. Many cancer stem cells do not have this versatility, and this is an essential difference between normal and cancer stem cells. In this report, we review findings that support this notion.

ARID1A prevents squamous cell carcinoma initiation and chemoresistance by antagonizing pRb/E2F1/c-Myc-mediated cancer stemness

Squamous cell carcinoma (SCC) is defined as a category of aggressive malignancies arising from the squamous epithelium of various organs. Resistance to chemotherapies is a common feature of SCCs, which leads to a poor prognosis among SCC patients. Recently, studies have illustrated the essential tumor suppressive role of ARID1A in several cancer types, but its role in SCCs remains unclear. Cancer stemness has been recognized as a main reason for tumorigenesis and is commonly correlated with chemoresistance, yet the relationship between ARID1A and cancer stemness remains unknown. In this study, we showed that Arid1a conditional knockout mice had a high incidence of SCCs occurring in the tongue and esophagus. ARID1A depletion promoted tumor initiation and cancer stemness in human SCC cells. Mechanistic studies revealed that ARID1A blocked the interaction between cyclin-dependent kinases (CDKs) and retinoblastoma protein (Rb), reducing the phosphorylation of Rb. Dephosphorylated Rb suppressed E2F1 activity and then suppressed cancer stemness by inactivating c-Myc. Furthermore, we showed that ARID1A depletion significantly increased the chemoresistance of SCC and that a CDK inhibitor exhibited a favorable effect on rescuing the chemoresistance caused by ARID1A loss. Collectively, our study showed that ARID1A inhibits the cancer stemness of SCCs by competing with CDKs to bind with Rb to inhibit the E2F1/c-Myc pathway.