Biology and immunology of cancer stem(-like) cells in head and neck cancer

VAV2 orchestrates the interplay between regenerative proliferation and ribogenesis in both keratinocytes and oral squamous cell carcinoma

VAV2 is an activator of RHO GTPases that promotes and maintains regenerative proliferation-like states in normal keratinocytes and oral squamous cell carcinoma (OSCC) cells. Here, we demonstrate that VAV2 also regulates ribosome biogenesis in those cells, a program associated with poor prognosis of human papilloma virus-negative (HPV-) OSCC patients. Mechanistically, VAV2 regulates this process in a catalysis-dependent manner using a conserved pathway comprising the RAC1 and RHOA GTPases, the PAK and ROCK family kinases, and the c-MYC and YAP/TAZ transcription factors. This pathway directly promotes RNA polymerase I activity and synthesis of 47S pre-rRNA precursors. This process is further consolidated by the upregulation of ribosome biogenesis factors and the acquisition of the YAP/TAZ-dependent undifferentiated cell state. Finally, we show that RNA polymerase I is a therapeutic Achilles' heel for both keratinocytes and OSCC patient-derived cells endowed with high VAV2 catalytic activity. Collectively, these findings highlight the therapeutic potential of modulating VAV2 and the ribosome biogenesis pathways in both preneoplastic and late progression stages of OSCC.

The Significance of Cancer Stem Cells and Epithelial-Mesenchymal Transition in Metastasis and Anti-Cancer Therapy

Cancer stem cells (CSCs) have been identified and characterized in both hematopoietic and solid tumors. Their existence was first predicted by Virchow and Cohnheim in the 1870s. Later, many studies showed that CSCs can be identified and isolated by their expression of specific cell markers. The significance of CSCs with respect to tumor biology and anti-cancer treatment lies in their ability to maintain quiescence with very slow proliferation, indefinite self-renewal, differentiation, and trans-differentiation such as epithelial-mesenchymal transition (EMT) and its reverse process mesenchymal-epithelial transition (MET). The ability for detachment, migration, extra- and intravasation, invasion and thereby of completing all necessary steps of the metastatic cascade highlights their significance for metastasis. CSCs comprise the cancer cell populations responsible for tumor growth, resistance to therapies and cancer metastasis. In this review, the history of the CSC theory, their identification and characterization and their biology are described. The contribution of the CSC ability to undergo EMT for cancer metastasis is discussed. Recently, novel strategies for drug development have focused on the elimination of the CSCs specifically. The unique functional and molecular properties of CSCs are discussed as possible therapeutic vulnerabilities for the development of novel anti-metastasis treatments. Prospectively, this may provide precise personalized anti-cancer treatments with improved therapeutic efficiency with fewer side effects and leading to better prognosis.

Advanced Nanomedicine for High-Risk HPV-Driven Head and Neck Cancer

The incidence of high-risk Human Papillomavirus (HR-HPV)-driven head and neck squamous cell carcinoma (HNSCC) is on the rise globally. HR-HPV-driven HNSCC displays molecular and clinical characteristics distinct from HPV-uninvolved cases. Therapeutic strategies for HR-HPV-driven HNSCC are under investigation. HR-HPVs encode the oncogenes E6 and E7, which are essential in tumorigenesis. Meanwhile, involvement of E6 and E7 provides attractive targets for developing new therapeutic regimen. Here we will review some of the recent advancements observed in preclinical studies and clinical trials on HR-HPV-driven HNSCC, focusing on nanotechnology related methods. Materials science innovation leads to great improvement for cancer therapeutics including HNSCC. This article discusses HPV-E6 or -E7- based vaccines, based on plasmid, messenger RNA or peptide, at their current stage of development and testing as well as how nanoparticles can be designed to target and access cancer cells and activate certain immunology pathways besides serving as a delivery vehicle. Nanotechnology was also used for chemotherapy and photothermal treatment. Short interference RNA targeting E6/E7 showed some potential in animal models. Gene editing by CRISPR-CAS9 combined with other treatments has also been assessed. These advancements have the potential to improve the outcome in HR-HPV-driven HNSCC, however breakthroughs are still to be awaited with nanomedicine playing an important role.

Mechanisms of immune evasion by head and neck cancer stem cells

Different mechanisms are involved in immune escape surveillance driven by Oral and Head and Neck Cancer Stem Cells (HNCSCs). The purpose of this review is to show the most current knowledge regarding the main impact of HNCSCs on tumor evasion through immunosuppression, CSCs phenotypes and environmental signals, highlighting strategies to overcome immune evasion. The main results drive the participation of cell surface receptors and secreted products and ligands, the crosstalk between cells, and genetic regulation. The reduction in CD8+ T cell recruitment and decreased effector of anti-PD-1 therapy by cells expressing BMI1 is a key event; Natural Killer cell ligands and cytokines needed for its activation and expansion are crucial to control tumor growth and to target CSCs by immunotherapy; CSCs expressing ALDH1 are related to increased expression of PD-L1, with a positive link between DNMT3b expression; CD276 expression in CSCs can act as a checkpoint inhibitor and together with Activator Protein 1 (AP-1) activation, they create continuous positive feedback that enables immune evasion by suppressing CD8+ T cells and prevent immune cell infiltration in head and neck cancer. These data demonstrate the relevance of the better understanding of the interaction between HNCSCs and immune cells in the tumor microenvironment. The ultimate clinical implication is to ground the choice of optimized targets and improve immune recognition for ongoing treatments as well as the response to approved immunotherapies.

Expression of aldehyde dehydrogenase 1A1 in oral squamous cell carcinoma and its correlation with clinicopathological parameters

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Precision Medicine Gains Momentum: Novel 3D Models and Stem Cell-Based Approaches in Head and Neck Cancer

Despite the current progress in the development of new concepts of precision medicine for head and neck squamous cell carcinoma (HNSCC), in particular targeted therapies and immune checkpoint inhibition (CPI), overall survival rates have not improved during the last decades. This is, on the one hand, caused by the fact that a significant number of patients presents with late stage disease at the time of diagnosis, on the other hand HNSCC frequently develop therapeutic resistance. Distinct intratumoral and intertumoral heterogeneity is one of the strongest features in HNSCC and has hindered both the identification of specific biomarkers and the establishment of targeted therapies for this disease so far. To date, there is a paucity of reliable preclinical models, particularly those that can predict responses to immune CPI, as these models require an intact tumor microenvironment (TME). The "ideal" preclinical cancer model is supposed to take both the TME as well as tumor heterogeneity into account. Although HNSCC patients are frequently studied in clinical trials, there is a lack of reliable prognostic biomarkers allowing a better stratification of individuals who might benefit from new concepts of targeted or immunotherapeutic strategies. Emerging evidence indicates that cancer stem cells (CSCs) are highly tumorigenic. Through the process of stemness, epithelial cells acquire an invasive phenotype contributing to metastasis and recurrence. Specific markers for CSC such as CD133 and CD44 expression and ALDH activity help to identify CSC in HNSCC. For the majority of patients, allocation of treatment regimens is simply based on histological diagnosis and on tumor location and disease staging (clinical risk assessments) rather than on specific or individual tumor biology. Hence there is an urgent need for tools to stratify HNSCC patients and pave the way for personalized therapeutic options. This work reviews the current literature on novel approaches in implementing three-dimensional (3D) HNSCC in vitro and in vivo tumor models in the clinical daily routine. Stem-cell based assays will be particularly discussed. Those models are highly anticipated to serve as a preclinical prediction platform for the evaluation of stable biomarkers and for therapeutic efficacy testing.

Molecular phenotypes of circulating tumor cells and efficacy of nivolumab treatment in patients with head and neck squamous cell carcinoma

The emergence of immune checkpoint inhibitors (ICIs) has revolutionized the treatment of recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC). Biomarkers of the therapeutic efficacy of ICIs have been extensively investigated. In this study, we aimed to analyze whether molecular phenotypes of circulating tumor cells (CTCs) are associated with treatment responses and clinical outcomes in patients with R/M HNSCC treated with nivolumab. Peripheral blood samples were collected before treatment initiation and after four infusions of nivolumab. CTCs isolated by depletion of CD45-positive cells were analyzed to determine the expression of EPCAM, MET, KRT19, and EGFR using real-time quantitative polymerase chain reaction. CTC-positive samples were analyzed to determine the expression of PIK3CA, CCND1, SNAI1, VIM, ZEB2, CD44, NANOG, ALDH1A1, CD47, CD274, and PDCD1LG2. Of 30 patients treated with nivolumab, 28 (93.3%) were positive for CTCs. In 20 CTC-positive patients, molecular alterations in CTCs before and after nivolumab treatment were investigated. Patients with MET-positive CTCs had significantly shorter overall survival than those with MET-negative CTCs (p = 0.027). The expression level of CCND1 in CTCs of disease-controlled patients was significantly higher than that of disease-progressed patients (p = 0.034). In disease-controlled patients, the expression level of CCND1 in CTCs significantly decreased after nivolumab treatment (p = 0.043). The NANOG expression in CTCs was significantly increased in disease-controlled patients after nivolumab treatment (p = 0.036). Our findings suggest that the molecular profiling of CTCs is a promising tool to predict the treatment efficacy of nivolumab.

Insights into Nanomedicine for Immunotherapeutics in Squamous Cell Carcinoma of the head and neck

Immunotherapies such as immune checkpoint blockade benefit only a portion of patients with head and neck squamous cell carcinoma. The multidisciplinary field of nanomedicine is emerging as a promising strategy to achieve maximal anti-tumor effect in cancer immunotherapy and to turn non-responders into responders. Various methods have been developed to deliver therapeutic agents that can overcome bio-barriers, improve therapeutic delivery into the tumor and lymphoid tissues and reduce adverse effects in normal tissues. Additional modification strategies also have been employed to improve targeting and boost cytotoxic T cell-based immune responses. Here, we review the state-of-the-art use of nanotechnologies in the laboratory, in advanced preclinical phases as well as those running through clinical trials assessing their advantages and challenges.

Prognostic Significance of the Pluripotency Factors NANOG, SOX2, and OCT4 in Head and Neck Squamous Cell Carcinomas

Cancer stem cells (CSCs) play major roles in tumor initiation, progression, and resistance to cancer therapy. Several CSC markers have been studied in head and neck squamous cell carcinomas (HNSCC), including the pluripotency factors NANOG, SOX2, and OCT4; however, their clinical significance is still unclear. NANOG, SOX2, and OCT4 expression was evaluated by immunochemistry in 348 surgically-treated HNSCC, and correlated with clinicopathological parameters and patient outcomes. mRNA expression was further analyzed in 530 The Cancer Genome Atlas (TCGA) HNSCC. NANOG protein expression was detected in 250 (72%) cases, more frequently in patients with lymph node metastasis (p = 0.003), and was an independent predictor of better survival in multivariate analysis. While OCT4 expression was undetectable, SOX2 expression was observed in 105 (30%) cases, and strongly correlated with NANOG expression. Combined expression of both proteins showed the highest survival rates, and double-negative cases the worst survival. Strikingly, the impact of NANOG and SOX2 on outcome varied depending on tumor site and lymph node infiltration, specifically showing prognostic significance in pharyngeal tumors. Correlation between NANOG and SOX2 at mRNA and protein was specifically observed in node positive (N+) patients, and consistently correlated with better survival rates. According to our findings, NANOG protein expression is frequent in HNSCC, thereby emerging as an independent predictor of better prognosis in pharyngeal tumors. Moreover, this study uncovers a differential impact of NANOG and SOX2 expression on HNSCC prognosis, depending on tumor site and lymph node infiltration, which could facilitate high-risk patient stratification.

Immunoregulatory Potential of Exosomes Derived from Cancer Stem Cells

Head and neck squamous cell carcinomas (HNSCCs) are malignancies that originate in the mucosal lining of the upper aerodigestive tract. Despite advances in therapeutic interventions, survival rates among HNSCC patients have remained static for years. Cancer stem cells (CSCs) are tumor-initiating cells that are highly resistant to treatment, and are hypothesized to contribute to a significant fraction of tumor recurrences. Consequently, further investigations of how CSCs mediate recurrence may provide insights into novel druggable targets. A key element of recurrence involves the tumor's ability to evade immunosurveillance. Recent published reports suggest that CSCs possess immunosuppressive properties, however, the underlying mechanism have yet to be fully elucidated. To date, most groups have focused on the role of CSC-derived secretory proteins, such as cytokines and growth factors. Here, we review the established immunoregulatory role of exosomes derived from mixed tumor cell populations, and propose further study of CSC-derived exosomes may be warranted. Such studies may yield novel insights into new druggable targets, or lay the foundation for future exosome-based diagnostics.

Immunotherapeutics for head and neck squamous cell carcinoma stem cells

Cancer stem cell (CSC)-related therapy resistance has become a new obstacle to the successful application of cancer treatment and head and neck squamous cell carcinoma (HNSCC) is no exception to this finding. Head and neck squamous cell carcinoma is highly immune-suppressive, and recently the immune suppression and invasion of HNSCC-CSCs have been characterized. These characteristics have received research and clinical attention because they would enable the stratification of patients into specific cancer subtypes and, consequently, the establishment of new therapeutic approaches with improved efficacy. This review discusses the feasibility of CSC-targeted strategies and their incorporation with nanotechnology to improve the efficacy of cancer immunotherapy.

Immunomethylomics: A Novel Cancer Risk Prediction Tool

There is emerging evidence that the immune biology associated with lung and other solid tumors, as well as patient immune genetic traits, contributes to individual survival. At this time, dramatic advances in immunologic approaches to the study and management of human cancers are taking place, including lung and head and neck squamous cell carcinoma. However, major obstacles for therapies are the profound immune alterations in blood and in the tumor microenvironment that arise in tandem with the cancer. Although there is a significant current effort underway across the cancer research community to probe the tumor environment to uncover the dynamics of the immune response, little similar work is being done to understand the dynamics of immune alterations in peripheral blood, despite evidence showing the prognostic relevance of the neutrophil/lymphocyte ratio for these cancers. A prominent feature of cancer-associated inflammation is the generation of myeloid-derived suppressor cells, which arise centrally in bone marrow myelopoiesis and peripherally in response to tumor factors. Two classes of myeloid-derived suppressor cells are recognized: granulocytic and monocytic. To date, such immune factors have not been integrated into molecular classification or prognostication. Here, we advocate for a more complete characterization of patient immune profiles, using DNA from archival peripheral blood after application of methylation profiling (immunomethylomics). At the heart of this technology are cell libraries of differentially methylated regions that provide the "fingerprints" of immune cell subtypes. Going forward, opportunities exist to explore aberrant immune profiles in the context of cancer-associated inflammation, potentially adding significantly to prognostic and mechanistic information for solid tumors.

LIN28: A cancer stem cell promoter for immunotherapy in head and neck squamous cell carcinoma

Lin28, a highly conserved RNA-binding protein, plays an important role in differentiation, metabolism, proliferation, pluripotency, and tumourigenicity. Lin28 overexpression promotes tumour-cell proliferation and metastasis in various human cancers, including head and neck cancer. Multiple studies demonstrate that Lin28 critically contributes to anti-tumour immunity and production of cancer stem cells in head and neck squamous cell carcinoma (HNSCC). Thus, Lin28 has potential application in HNSCC treatment.

Tumor-derived exosomes (TDEs): How to avoid the sting in the tail

Exosomes are abundantly secreted extracellular vesicles that accumulate in the circulation and are of great interest for disease diagnosis and evaluation since their contents reflects the phenotype of their cell of origin. Tumor‐derived exosomes (TDEs) are of particular interest for cancer diagnosis and therapy, since most tumor demonstrate highly elevated exosome secretion rates and provide specific information about the genotype of a tumor and its response to treatment. TDEs also contain regulatory factors that can alter the phenotypes of local and distant tissue sites and alter immune cell functions to promote tumor progression. The abundance, information content, regulatory potential, in vivo half‐life, and physical durability of exosomes suggest that TDEs may represent a superior source of diagnostic biomarkers and treatment targets than other materials currently under investigation. This review will summarize current information on mechanisms that may differentially regulate TDE biogenesis, TDE effects on the immune system that promote tumor survival, growth, and metastasis, and new approaches understudy to counteract or utilize TDE properties in cancer therapies.

The Head and Neck Squamous Cell Carcinoma Microenvironment as a Potential Target for Cancer Therapy

Similarly to other types of malignant tumours, the incidence of head and neck cancer is increasing globally. It is frequently associated with smoking and alcohol abuse, and in a broader sense also with prolonged exposure to these factors during ageing. A higher incidence of tumours observed in younger populations without a history of alcohol and tobacco abuse may be due to HPV infection. Malignant tumours form an intricate ecosystem of cancer cells, fibroblasts, blood/lymphatic capillaries and infiltrating immune cells. This dynamic system, the tumour microenvironment, has a significant impact on the biological properties of cancer cells. The microenvironment participates in the control of local aggressiveness of cancer cells, their growth, and their consequent migration to lymph nodes and distant organs during metastatic spread. In cancers originating from squamous epithelium, a similarity was demonstrated between the cancer microenvironment and healing wounds. In this review, we focus on the specificity of the microenvironment of head and neck cancer with emphasis on the mechanism of intercellular crosstalk manipulation for potential therapeutic application.

Heterogeneity of Head and Neck Squamous Cell Carcinoma Stem Cells

Current systemic cancer treatment in head and neck squamous cell carcinoma (HNSCC) is moving toward more personalized approaches such as de-escalation protocols human-papilloma-virus dependent HNSCC or application of checkpoint inhibitors. However, these treatments have been challenged by cancer stem cells (CSC), a small population within the bulk tumor, which are leading to treatment failure, tumor recurrence, or metastases. This review will give an overview of the characteristics of HNSCC-CSC. Specifically, the mechanisms by which HNSCC-CSC induce tumor initiation, progression, recurrence, or metastasis will be discussed. Although evidence-based treatment options targeting HNSCC-CSC specifically are still being sought for, they warrant a promise for additional and sustainable treatment options where for HNSCC patients where others have failed.

Phenotype of p53 wild-type epitope-specific T cells in the circulation of patients with head and neck cancer

CD8⁺ cytotoxic T-cell (CTL) specific for non-mutated, wild type (wt) sequence p53 peptides derived from wt or mutant p53 molecules expressed in head and neck squamous cell carcinomas (HNSCC) have been detected in the circulation of patients with this disease. The frequency and differentiation/maturation phenotypes of these anti-tumor specific CTL can reflect the host’s immunologic response. Therefore, we investigated the frequency and phenotypes of wt sequence p53 peptide-specific CTL in patients with HNSCC (n = 33) by flow cytometric analysis using HLA-A*0201 tetrameric peptides (tet) complexed with the wt sequence p53_264–272 or p53_149–157 peptide and co-staining with phenotypic markers. One main finding was that increasing frequencies of tet⁺ CD8⁺ T cells in patients’ circulation correlated with increased frequencies of inactive naïve tet⁺ cells, while those with effector memory and terminally differentiated phenotypes, which are associated with positive anti-tumor immune responses, decreased. We also found that the frequency of circulating tet⁺ CD8⁺ T cells negatively correlated with p53 expression in tumor tissues and tumor stage. Our findings support further clinical-based investigations to define the frequencies and phenotypes of wt sequence p53 peptide-specific CD8⁺ T cells to predict disease severity, enhance selection of patients for inclusion in vaccination trials and highlight prerequisites to enhance immune susceptibility by activation of inactive naïve tet⁺ T cells and/or enhancing circulating effector T cell activity by checkpoint blockage.

DSPP-MMP20 gene silencing downregulates cancer stem cell markers in human oral cancer cells

BACKGROUND

Recent findings indicate that dentin sialophosphoprotein (DSPP) and matrix metalloproteinase (MMP) 20 interact in oral squamous cell carcinoma (OSCC). The objective of this study was to determine the effects of DSPP/MMP20 gene silencing on oral cancer stem cell (OCSC) markers.

METHODS

The expression of well-established OCSC markers: ABCG2; ALDH1; CD133; CD44; BMI1; LGR4, and Podoplanin in DSPP/MMP20-silenced OSCC cell line, OSC2, and controls were assayed by western blot (WB), and flow cytometry techniques. The sensitivity of OSC2 cells to cisplatin following DSPP/MMP20 silencing was also determined.

RESULTS

DSPP/MMP20 silencing resulted in downregulation of OCSC markers, more profoundly ABCG2 (84%) and CD44 (81%), following double silencing. Furthermore, while treatment of parent (pre-silenced) OSC2 cells with cisplatin resulted in upregulation of OCSC markers, DSPP/MMP20-silenced OSC2 cells similarly treated resulted in profound downregulation of OCSC markers (72 to 94% at 50 μM of cisplatin), and a marked reduction in the proportion of ABCG2 and ALDH1 positive cells (~ 1%).

CONCLUSIONS

We conclude that the downregulation of OCSC markers may signal a reduction in OCSC population following MMP20/DSPP silencing in OSCC cells, while also increasing their sensitivity to cisplatin. Thus, our findings suggest a potential role for DSPP and MMP20 in sustaining OCSC population in OSCCs, possibly, through mechanism(s) that alter OCSC sensitivity to treatment with chemotherapeutic agents such as cisplatin.

Reactive oxygen species in cancer stem cells of head and neck squamous cancer

One of the greatest challenges in systemic treatment of head and neck squamous cell carcinoma (HNSCC) is a small tumor cell population, namely, cancer stem-like cells (CSC). CSC can regenerate and maintain a heterogenic tumor by their self-renewal capacity. Their potential ability to be more resistant to and survival after chemo- and radiation therapy was also identified. Further studies have shown that reactive oxygen species (ROS) contribute to this CSC-associated resistance. In this review, we focus on the current knowledge of HNSCC-CSC, with regard to ROS as a possible and novel therapeutic approach in targeting CSC.

CD44 and ALDH1 immunoexpression as prognostic indicators of invasion and metastasis in oral squamous cell carcinoma

BACKGROUND

Tumour metastasis has been associated with cancer stem cells, a small population with stem-like cells properties, higher rate of migration and metastatic potential compared to cells from the tumour bulk. Our aim was to evaluate the immunoexpression of the putative cancer stem cell biomarkers ALDH1 and CD44 in primary tumour and corresponding metastatic lymph nodes.

METHODS

Tumour tissue specimens (n = 50) and corresponding metastatic lymph nodes (n = 25) were surgically obtained from 50 patients with oral squamous cell carcinoma and submitted to immunohistochemistry. CD44 and ALDH1 were semi-quantitatively scored according to the proportion and intensity of positive cells within the invasive front and metastatic lymph nodes as a whole. A combined score was obtained by multiplying both parameters and later dichotomized into a final score classified as low (≤2) or high (>2) immunoexpression.

RESULTS

ALDH1 immunoexpression and CD44 immunoexpression were detected in both tumour sites, although the means of ALDH1 (P = .0985) and CD44 (P = .4220) cells were higher in metastasis compared to primary tumours. ALDH1^high was positively associated (P = .0184) with angiolymphatic invasion, while CD44^high was positively associated (P = .0181) with metastasis (N+). At multivariate analysis, CD44 significantly increased the odds of lymph node metastasis, regardless of T stage (OR = 8.24; 1.64-65.64, P = .0088).

CONCLUSIONS

CD44 immunoexpression was a significant predictor of lymph node metastasis, while ALDH1^high immunostaining was associated with angiolymphatic invasion. Altogether, it suggests that immunoexpression of CD44 and ALDH1 links the cancer stem cell phenotype with oral squamous cell carcinoma invasion and metastasis.

Prognostic implications of CD44, NANOG, OCT4, and BMI1 expression in tongue squamous cell carcinoma

BACKGROUND

Tongue squamous cell carcinoma (SCC) contains a cell subpopulation referred to as cancer stem cells (CSCs), which are responsible for tumor growth, metastasis, and resistance to chemotherapy and radiotherapy. The CSC markers have been used to isolate these cells and as biomarkers to predict overall survival.

METHODS

The CSC markers CD44, NANOG, OCT4, and BMI1 were investigated using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry and correlated with clinicopathological parameters.

RESULTS

The CD44 overexpression was associated with disease-related death (P = 0.02) and worst prognosis. NANOG was upregulated in nontumoral margins and associated with T1/T2 classification, lymph node metastasis, and worst prognosis. OCT4 was associated with lymph node metastasis and worst overall survival. BMI1 and CD44v3 were overexpressed in tongue SCC. Coexpression of CD44⁺⁺ /NANOG⁺⁺ was associated with worst overall survival when compared with patients with CD44^-/+ /NANOG^-/+ .

CONCLUSION

The CSC markers might play an important role not only in CSC trait acquisition but also in tongue SCC development and progression.

CD73 Regulates Stemness and Epithelial-Mesenchymal Transition in Ovarian Cancer-Initiating Cells

Cancer-initiating cells (CICs) have been implicated in tumor development and aggressiveness. In ovarian carcinoma (OC), CICs drive tumor formation, dissemination, and recurrence, as well as drug resistance, thus accounting for the high death-to-incidence ratio of this neoplasm. However, the molecular mechanisms that underlie such a pathogenic role of ovarian CICs (OCICs) remain elusive. Here, we have capitalized on primary cells either from OC or from its tissues of origin to obtain the transcriptomic profile associated with OCICs. Among the genes differentially expressed in OCICs, we focused on CD73, which encodes the membrane-associated 5′-ectonucleotidase. The genetic inactivation of CD73 in OC cells revealed that this molecule is causally involved in sphere formation and tumor initiation, thus emerging as a driver of OCIC function. Furthermore, functional inhibition of CD73 via either a chemical compound or a neutralizing antibody reduced sphere formation and tumorigenesis, highlighting the druggability of CD73 in the context of OCIC-directed therapies. The biological function of CD73 in OCICs required its enzymatic activity and involved adenosine signaling. Mechanistically, CD73 promotes the expression of stemness and epithelial-mesenchymal transition-associated genes, implying a regulation of OCIC function at the transcriptional level. CD73, therefore, is involved in OCIC biology and may represent a therapeutic target for innovative treatments aimed at OC eradication.

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CD73 is enriched in ovarian cancer-initiating cells (OCICs)

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CD73 orchestrates OCIC stemness and EMT

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OC initiation and growth require CD73 activity

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OCIC-associated CD73 is a therapeutic target useful for OC eradication

Aldehyde dehydrogenase 1 isoenzyme expression as a marker of cancer stem cells correlates to histopathological features in head and neck cancer: A meta-analysis

There is a lack of predictive biomarkers that can identify patients with head and neck squamous cell carcinoma (HNSCC) who will experience treatment failure and develop drug resistance, recurrence, and metastases. Cancer stem-like cells (CSC) were identified as a subset of cells within the tumor in a variety of solid tumors including HNSCC. CSC are considered the tumor-initiating population responsible for recurrence or metastasis and are associated with therapy resistance. This meta-analysis including fourteen studies with altogether 1258 patients updates and summarizes all relevant data on the impact of ALDH1⁺ CSC on the prognosis of HNSCC and its association with clinicopathological parameters. ALDH1 expression is highly correlated with tumor differentiation (G3 vs. G1+G2; odds ratio = 2.85. 95% CI: 1.72–4.73, P<0.0001) and decreased overall survival (relative risk = 1.77. 95% CI: 1.41–2.22, P<0.0001) if one out of seven studies was excluded because of heterogeneity. These findings provide insights into the understanding of more aggressive tumor phenotypes and also suggest that the prognostic value provided by HNSCC-subtyping by CSC frequency warrant further clinical investigation.

Prognostic Value of Cancer Stem Cell Markers in Head and Neck Squamous Cell Carcinoma: a Meta-analysis

Bmi-1, CD133, Nanog and Oct-4 have been reported as cancer stem cell (CSC) markers in head and neck squamous cell carcinoma (HNSCC). However, the prognostic value of them in HNSCC remains controversial. Hence, this meta-analysis was conducted to access the association between the four CSC markers and survival outcome of HNSCC patients. A total of 22 articles with 27 studies met the inclusion criteria and the combined hazard ratio (HR) and 95% confidence intervals (95% CI) were calculated. Data analysis showed that high expression of CSC markers was associated with poor overall survival (OS) (HR = 1.93; 95% CI: 1.46–2.55, P < 0.001) and disease free survival (DFS) (HR = 4.78; 95% CI: 2.95–7.75, P < 0.001) but not disease specific survival (DSS) (HR = 1.17; 95% CI: 0.74–1.84, P = 0.50) of HNSCC patients. Subgroup analysis indicted that high expression of CD133 (HR = 2.33, 95%CI: 1.42–3.83, P < 0.001), Oct-4(HR = 2.10, 95%CI: 1.36–3.22, P = 0.007) and Nanog (HR = 2.49, 95%CI: 1.66–3.72, P < 0.001) could predict poor OS in HNSCC patients respectively whereas overexpression of Bmi-1 was not related to the reduced OS in HNSCC patients (HR = 1.32, 95%CI: 0.66–2.65, P = 0.43). Therefore, we concluded that CSC markers, especially CD133, Nanog and Oct-4, might be predictive factors in HNSCC patients.

ACTL6A Is Co-Amplified with p63 in Squamous Cell Carcinoma to Drive YAP Activation, Regenerative Proliferation, and Poor Prognosis

Loss-of-function mutations in SWI/SNF chromatin-remodeling subunit genes are observed in many cancers, but an oncogenic role for SWI/SNF is not well established. Here, we reveal that ACTL6A, encoding an SWI/SNF subunit linked to stem cell and progenitor cell function, is frequently co-amplified and highly expressed together with the p53 family member p63 in head and neck squamous cell carcinoma (HNSCC). ACTL6A and p63 physically interact, cooperatively controlling a transcriptional program that promotes proliferation and suppresses differentiation, in part through activation of the Hippo-YAP pathway via regulators including WWC1. Ectopic ACTL6A/p63 expression promotes tumorigenesis, while ACTL6A expression and YAP activation are highly correlated in primary HNSCC and predict poor patient survival. Thus, ACTL6A and p63 collaborate as oncogenic drivers in HNSCC.

Expression of aldehyde dehydrogenase family 1 member A1 and high mobility group box 1 in oropharyngeal squamous cell carcinoma in association with survival time

Despite the development of novel multimodal treatment combinations in advanced oropharyngeal squamous cell carcinoma (OSCC), outcomes remain poor. The identification of specifically validated biomarkers is required to understand the underlying molecular mechanisms, to evaluate treatment efficiency and to develop novel therapeutic targets. The present study, therefore, examined the presence of aldehyde dehydrogenase family 1 member A1 (ALDH1A1) and high mobility group box 1 (HMGB1) expression in primary OSCC and analyzed the impact on survival time. In 59 patients with OSCC, the expression of ALDH1A1, p16 and HMGB1, and their clinicopathological data were analyzed. HMGB1 positivity was significantly increased in patients with T1-2 stage disease compared with T3-4 stage disease (P<0.001), whereas ALDH1A1 positivity was not. ALDH1A1⁺ tumors showed significantly lower differentiation than ALDH1A1^- tumors (P=0.018). Multivariate analysis showed that ALDH1A1 positivity (P=0.041) and nodal status (N2-3) (P=0.036) predicted a poor prognosis. In this patient cohort, ALDH1A1 and nodal status were identified as independent predictors of a shorter overall survival time. The study results, therefore, provide evidence of the prognostic value of ALDH1A1 as a marker for cancer stem cells and nodal status in OSCC patients.

Differential Expression of Stem Cell Markers in Ocular Surface Squamous Neoplasia

Ocular Surface Squamous Neoplasm (OSSN) is the neoplasia arising from the conjunctiva, cornea and limbus. OSSN ranges from mild, moderate, severe dysplasia, carcinoma in situ (CIS) to squamous cell carcinoma (SCC). Recent findings on cancer stem cells theory indicate that population of stem-like cell as in neoplasia determines its heterogeneity and complexity leading to varying tumor development of metastatic behavior and recurrence. Cancer stem cell markers are not much explored in the cases of OSSN. In the present study, we aim to evaluate the expression of stem cells using stem cell markers mainly p63, ABCG2, c-KIT (CD117) and CD44 in OSSN tissue, which could have prognostic significance. The present study tries for the first time to explore expression of these stem markers in the cases of OSSN. These cases are subdivided into two groups. One group comprises of carcinoma in situ (n = 6) and the second group comprises of invasive carcinoma (n = 6). The mean age at presentation was 52 years; with 53 years for CIS group and 52 years for SCC group. From each group section from the paraffin block were taken for the IHC staining of p63, c-Kit, ABCG2 and CD44. Our experiments show high expression of P63 and CD44 in the cases of CIN and SCC. Both CIS and SCC displayed positive staining with p63, with more than 80% cells staining positive. However minimal expression of c-kit in both CIN and SCC. But surprisingly we got high expression of ABCG2 in cases of carcinoma in situ as compared to that of invasive squamous cell carcinoma. More than 50% of cells showed CD44 positivity in both CIS and SCC groups. Our results show for the first time that these four stem cells especially the limbal epithelium stem cells play a vital role in the genesis of OSSN but we need to explore more cases before establishing its clinical and biological significance.

A new complementary procedure for patients affected by head and neck cancer: Chemo-predictive assay

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Cancer stem cells (CSCs) resist chemotherapy, thereby causing relapse of the disease.

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A new chemotherapy drug response assay (ChemoID), which measures the sensitivity of CSCs to a variety of chemotherapy agents has been developed.

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The ChemoID assay may assist an oncologist in making treatment decisions.

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The ChemoID procedure may lower treatment costs by eliminating ineffective chemotherapies and unnecessary toxicity.

Introduction

Administration of ineffective anticancer therapy is associated with unnecessary toxicity and development of resistant clones. Cancer stem cells (CSCs) resist chemotherapy, thereby causing relapse of the disease. Thus, development of a test that identifies the most effective chemotherapy management offers great promise for individualized anticancer treatments. We have developed an ex vivo chemotherapy drug response assay (ChemoID^®), which measures the sensitivity of CSCs as well as the bulk of tumor cells to a variety of chemotherapy agents to assist an oncologist in making treatment decisions.

Methods

Three patients affected by oral cancer were referred.

Results

Biopsy showed a well-differentiated squamous cell carcinoma (G1) in case 1, a G2 adenocarcinoma in case 2 and a G3 squamous cell carcinoma in case 3. In all of the three cases, after clinical inspection and suspicion of a diagnosis of cancer, a double biopsy was performed. One specimen was sent to the ChemoID laboratory for chemosensitivity assay and the other for histological analysis. Chemotherapy dose response curves were generated, and grouped in 3 categories: 1. No response (less than 30% cell kill), Intermediate (30–60% cell kill), and 3. Sensitive (60% cell kill or above).

Conclusions

This procedure may be useful in helping physicians choose an effective chemotherapy regimen for head and neck cancer patients and lower treatment costs by eliminating ineffective chemotherapies and unnecessary toxicity particularly in elderly patients.

HGF/Met Signaling in Head and Neck Cancer: Impact on the Tumor Microenvironment

Studies to date have revealed several major molecular alterations that contribute to head and neck squamous cell carcinoma (HNSCC) initiation, progression, metastatic spread, and therapeutic failure. The EGFR is the only FDA-approved therapeutic target, yet responses to cetuximab have been limited. Activation and cross-talk of cellular receptors and consequent activation of different signaling pathways contribute to limited activity of blockade of a single pathway. The hepatocyte growth factor (HGF) receptor, Met, has been implicated in HNSCC tumorigenesis and EGFR inhibitor resistance. HGF, the sole ligand of Met, is overexpressed in the tumor microenvironment. The role of HGF/Met signaling in proliferation, metastasis, and angiogenesis has been investigated in HNSCC, leading to clinical trials with various Met inhibitors and HGF antibodies. However, the role of the HGF/Met signaling axis in mediating the tumor microenvironment has been relatively understudied in HNSCC. In this review, we discuss the functional roles of Met and HGF in HNSCC with a focus on the tumor microenvironment and the immune system. Clin Cancer Res; 22(16); 4005-13. ©2016 AACR.

The emerging role of immunotherapy in head and neck squamous cell carcinoma (HNSCC): anti-tumor immunity and clinical applications

Head and neck squamous cell carcinoma (HNSCC) carries a poor prognosis, with low survival rates for advanced stage tumors and minimal improvement in survival trends through the past decades. It is becoming increasingly clear that HNSCC oncogenesis and evolution is characterized by profound immune defects, as cancer cells evade immunosurveillance due to accumulation of genetic mutations and tumor heterogeneity. Improved understanding of the role of the immune system in cancer has led to the identification of novel therapeutic targets, which are being investigated for their potential to provide durable responses. In this review, we will summarize the role of the immune system in HNSCC, the rationale behind immunotherapy strategies and their clinical applications.

Monitoring cancer stem cells: insights into clinical oncology

Cancer stem cells (CSCs) are a small, characteristically distinctive subset of tumor cells responsible for tumor initiation and progression. Several treatment modalities, such as surgery, glycolytic inhibition, driving CSC proliferation, immunotherapy, and hypofractionated radiotherapy, may have the potential to eradicate CSCs. We propose that monitoring CSCs is important in clinical oncology as CSC populations may reflect true treatment response and assist with managing treatment strategies, such as defining optimal chemotherapy cycles, permitting pretreatment cancer surveillance, conducting a comprehensive treatment plan, modifying radiation treatment, and deploying rechallenge chemotherapy. Then, we describe methods for monitoring CSCs.

Survivin Modulates Squamous Cell Carcinoma-Derived Stem-Like Cell Proliferation, Viability and Tumor Formation in Vivo

Squamous Cell Carcinoma-derived Stem-like Cells (SCC-SC) originate from alterations in keratinocyte stem cells (KSC) gene expression and sustain tumor development, invasion and recurrence. Since survivin, a KSC marker, is highly expressed in SCC-SC, we evaluate its role in SCC-SC cell growth and SCC models. Survivin silencing by siRNA decreases clonal growth of SCC keratinocytes and viability of total, rapidly adhering (RAD) and non-RAD (NRAD) cells from primary SCC. Similarly, survivin silencing reduces the expression of stem cell markers (OCT4, NOTCH1, CD133, β₁-integrin), while it increases the level of differentiation markers (K10, involucrin). Moreover, survivin silencing improves the malignant phenotype of SCC 3D-reconstruct, as demonstrated by reduced epidermal thickness, lower Ki-67 positive cell number, and decreased expression of MMP9 and psoriasin. Furthermore, survivin depletion by siRNA in Ras^G12V-IκBα-derived tumors leads to smaller tumor formation characterized by lower mitotic index and reduced expression of the tumor-associated marker HIF1α, VEGF and CD51. Therefore, our results indicate survivin as a key gene in regulating SCC cancer stem cell formation and cSCC development.