Expression and role of the embryonic protein SOX2 in head and neck squamous cell carcinoma

Combination of monensin and erlotinib synergistically inhibited the growth and cancer stem cell properties of triple-negative breast cancer by simultaneously inhibiting EGFR and PI3K signaling pathways

BACKGROUND

Cancer stem cells (CSCs) in triple-negative breast cancer (TNBC) are recognized as a highly challenging subset of cells, renowned for their heightened propensity for relapse and unfavorable prognosis. Monensin, an ionophoric antibiotic, has been reported to exhibit significant therapeutic efficacy against various cancers, especially CSCs. Erlotinib is classified as one of the EGFR-TKIs and has been previously identified as a promising therapeutic target for TNBC. Our research aims to assess the effectiveness of combination of monensin and erlotinib as a potential treatment strategy for TNBC.

METHODS

The combination of monensin and erlotinib was assessed for its potential anticancer activity through various in vitro assays, including cytotoxicity assay, colony formation assay, wound healing assay, transwell assay, mammosphere formation assay, and proportion of CSCs assay. Additionally, an in vivo study using tumor-bearing nude mice was conducted to evaluate the inhibitory effect of the monensin and erlotinib combination on tumor growth.

RESULTS

The results indicated that combination of monensin with erlotinib synergistically inhibited cell proliferation, the migration rate, the invasion ability and decreased the CSCs proportion, and CSC markers SOX2 and CD133 in vivo and in vitro. Furthermore, the primary proteins involved in the signaling pathways of the EGFR/ERK and PI3K/AKT are simultaneously inhibited by the combination treatment of monensin and erlotinib in vivo and in vitro.

CONCLUSIONS

The simultaneous inhibition of the EGFR/ERK and PI3K/AKT/mTOR signaling pathways by the combination of monensin and erlotinib exhibited a synergistic effect on suppressing tumor proliferation and cancer cell stemness in TNBC.

The molecular characteristics of recurrent/metastatic HPV-positive head and neck squamous cell carcinoma: A systematic review of the literature

OBJECTIVES

About 17% of patients with human papillomavirus (HPV)-positive head and neck squamous cell carcinoma (HNSCC), which is mainly comprised of oropharyngeal SCC (OPSCC), will experience disease recurrence, which is often considered incurable when manifested at a metastatic and/or recurrent stage. We conducted a critical qualitative systematic review. Our objectives were to provide an overview of the molecular landscape of recurrent/metastatic HPV-positive HNSCC as well as novel molecular biomarkers.

DESIGN

A literature review was conducted to identify studies reporting on the molecular characteristics of recurrent/metastatic HPV-positive HNSCC, novel molecular biomarkers and treatment options. The reviews of abstracts, full articles, and revision of the included studies, followed by data extraction and quality assessment were performed by three independent assessors. All primary literature, such as retrospective, prospective, and clinical trials as well as basic research studies were considered, and the final search was conducted at the end of February 2023. The level of evidence was rated using the guidelines published by the Oxford Centre for Evidence-based Medicine and quality was assessed using the Newcastle-Ottawa Scale criteria.

RESULTS AND CONCLUSIONS

The literature search resulted in the identification of 1991 articles. A total of 181 full articles were screened, and 66 articles were included in this analysis. Several studies reported that recurrent/metastatic HPV-positive HNSCC had higher rates of TP53 mutation and were genomically similar to HPV-negative HNSCC. The detection of circulating tumour tissue-modified HPV DNA (ctHPVDNA) as a specific biomarker has shown promising results for monitoring treatment response and recurrence in the subset of HPV-positive HNSCC. In addition, evidence for targeted therapy in recurrent/metastatic HPV-positive HNSCC has emerged, including agents that inhibit overexpressed EGFR. Studies of combination immunotherapy are also underway. Our review outlines the latest evidence on the distinct molecular profiles of recurrent/metastatic HPV-positive HNSCC as well as the clinical potential of ctHPVDNA testing in routine practice. More controlled and longitudinal studies are needed to identify additional molecular targets and to assess the performance and benefits of novel molecular biomarkers in clinical practice.

SOX2-associated signaling pathways regulate biological phenotypes of cancers

SOX2 is a transcription factor involved in multiple stages of embryonic development. In related reports, SOX2 was found to be abnormally expressed in tumor tissues and correlated with clinical features such as TNM staging, tumor grade, and prognosis in patients with various cancer types. In most cancer types, SOX2 is a tumor-promoting factor that regulates tumor progression and metastasis primarily by maintaining the stemness of cancer cells. In addition, SOX2 also regulates the proliferation, apoptosis, invasion, migration, ferroptosis and drug resistance of cancer cells. However, SOX2 acts as a tumor suppressor in some cases in certain cancer types, such as gastric and lung cancer. These key regulatory functions of SOX2 involve complex regulatory networks, including protein-protein and protein-nucleic acid interactions through signaling pathways and noncoding RNA interactions, modulating SOX2 expression may be a potential therapeutic strategy for clinical cancer patients. Therefore, we sorted out the phenotypes related to SOX2 in cancer, hoping to provide a basis for further clinical translation.

CDK5RAP2 is a Wnt target gene and promotes stemness and progression of oral squamous cell carcinoma

In oral squamous cell carcinoma (OSCC), a highly aggressive and frequently lethal malignancy, the role and action mechanism of the microtubule regulatory protein CDK5RAP2 have not been fully understood. Here, we show that CDK5RAP2 is highly expressed in OSCC and its expression correlates with clinical stage and lymph node metastasis of the disease. The expression of CDK5RAP2 is regulated by the Wnt signaling pathway. Depletion of CDK5RAP2 inhibits the tumorigenesis and migration of OSCC cells and alters the OSCC cancer stem (-like) cell (CSC) signature. Notably, suppression of CDK5RAP2 expression disrupts spindle orientation during mitosis. Collectively, these results identify CDK5RAP2 as a potential CSC marker and reveal a mechanism that controls the CSC population in OSCC.

Mechanisms involved in cancer stem cell resistance in head and neck squamous cell carcinoma

Despite scientific advances in the Oncology field, cancer remains a leading cause of death worldwide. Molecular and cellular heterogeneity of head and neck squamous cell carcinoma (HNSCC) is a significant contributor to the unpredictability of the clinical response and failure in cancer treatment. Cancer stem cells (CSCs) are recognized as a subpopulation of tumor cells that can drive and maintain tumorigenesis and metastasis, leading to poor prognosis in different types of cancer. CSCs exhibit a high level of plasticity, quickly adapting to the tumor microenvironment changes, and are intrinsically resistant to current chemo and radiotherapies. The mechanisms of CSC-mediated therapy resistance are not fully understood. However, they include different strategies used by CSCs to overcome challenges imposed by treatment, such as activation of DNA repair system, anti-apoptotic mechanisms, acquisition of quiescent state and Epithelial-mesenchymal transition, increased drug efflux capacity, hypoxic environment, protection by the CSC niche, overexpression of stemness related genes, and immune surveillance. Complete elimination of CSCs seems to be the main target for achieving tumor control and improving overall survival for cancer patients. This review will focus on the multi-factorial mechanisms by which CSCs are resistant to radiotherapy and chemotherapy in HNSCC, supporting the use of possible strategies to overcome therapy failure.

CXCR3 isoform A promotes head and neck cancer progression by enhancing stem-like property and chemoresistance

The chemokine network orchestrates the cancer stem-like property and consequently participates in cancer progression. CXCR3 contributes cancer progressive property and immunomodulation in the tumor microenvironment. The two major isoforms of CXCR3 are scrutinized and the divergence is showed that CXCR3A promotes cancer cell growth and motility while CXCR3B functions contrarily in many studies. However, rare studies illustrate the role of CXCR3 isoforms in cancer stem-like property and chemoresistance, especially in head and neck cancer (HNC). First, we used immunohistochemistry staining to evaluate expression levels of CXCR3, CXCR3B, and Sox2 cancer stem cell (CSC) marker and association with tumor progression in HNC tissues. Results showed that high levels of CXCR3 were significantly associated with advanced stage (p <0.01), regional lymph node metastasis (p <0.05), and poor differentiation (p <0.005) and further correlated with worse survival rate in oral cancer patients (p = 0.036). Higher levels of CXCR3B were found in regional lymphatic invasion of HNC and progressive stage of squamous cell carcinoma. Elevated Sox2 expression was significantly associated with the advanced stage of HNC in the oral cavity, and demonstrated a co-expression pattern with CXCR3B. Furthermore, lentivirus-mediated overexpression of CXCR3A and CXCR3B in SAS human oral cancer cells promoted cell mobility. CXCR3A overexpression enhanced sphere-forming ability and chemoresistance of CSCs by upregulating stemness-related genes. This study first provides a novel insight of CXCR3 isoform A in HNC cancer progression via regulating cancer stem-like properties and chemoresistance, suggesting that CXCR3A may be a prognostic marker and novel target for HNC therapy.

Prognostic and predictive roles of cancer stem cell markers in head and neck squamous cell carcinoma patients receiving chemoradiotherapy with or without nimotuzumab

BACKGROUND

Anti-EGFR-based therapies have limited success in HNSCC patients. Predictive biomarkers are needed to identify the patients most likely to benefit from these therapies. Here, we present predictive and prognostic associations of different cancer stem cell markers in HPV-negative locally advanced (LA) HNSCC patients.

METHODS

Pretreatment tumour tissues of 404 HPV-negative LA-HNSCCs patients, a subset of-phase 3-randomised study comparing cisplatin-radiation(CRT) and nimotuzumab plus cisplatin-radiation(NCRT) were examined. The expression levels of CD44, CD44v6, CD98hc, ALDH1A1, SOX2 and OCT4A were evaluated using immunohistochemistry. Progression-free survival(PFS), loco-regional control(LRC),- and overall survival(OS) were estimated by Kaplan-Meier method. Hazard ratios were estimated by Cox proportional hazard models.

RESULTS

NCRT showed significantly improved OS with low membrane expression of CD44 compared to CRT [HR (95% CI) = 0.63 (0.46-0.88)]. Patients with low CD44v6 also showed better outcomes with NCRT [LRC: HR (95% CI) = 0.25 (0.10-0.62); OS: HR (95% CI) = 0.38 (0.19-0.74)]. No similar benefit with NCRT observed in patients with high CD44 or CD44v6 expression. Bootstrap resampling confirmed the predictive effect of CD44 (Interaction P = 0.015) and CD44v6 (Interaction P = 0.041) for OS. Multivariable Cox analysis revealed an independent negative prognostic role of CD98hc membrane expression for LRC [HR (95% CI) = 0.63(0.39-1.0)] and OS[HR (95% CI) = 0.62 (0.40-0.95)].

CONCLUSIONS

CD44 and CD44v6 are potential predictive biomarkers for NCRT response. CD98hc emerged as an independent negative prognostic biomarker.

CLINICAL TRIAL REGISTRATION

Registered with the Clinical Trial Registry of India (Trial registration identifier-CTRI/2014/09/004980).

Oral Cancer Stem Cells: Therapeutic Implications and Challenges

Head and neck squamous cell carcinoma (HNSCC) is currently one of the 10 most common malignancies worldwide, characterized by a biologically highly diverse group of tumors with non-specific biomarkers and poor prognosis. The incidence rate of HNSCC varies widely throughout the world, with an evident prevalence in developing countries such as those in Southeast Asia and Southern Africa. Tumor relapse and metastasis following traditional treatment remain major clinical problems in oral cancer management. Current evidence suggests that therapeutic resistance and metastasis of cancer are mainly driven by a unique subpopulation of tumor cells, termed cancer stem cells (CSCs), or cancer-initiating cells (CICs), which are characterized by their capacity for self-renewal, maintenance of stemness and increased tumorigenicity. Thus, more understanding of the molecular mechanisms of CSCs and their behavior may help in developing effective therapeutic interventions that inhibit tumor growth and progression. This review provides an overview of the main signaling cascades in CSCs that drive tumor repropagation and metastasis in oral cancer, with a focus on squamous cell carcinoma. Other oral non-SCC tumors, including melanoma and malignant salivary gland tumors, will also be considered. In addition, this review discusses some of the CSC-targeted therapeutic strategies that have been employed to combat disease progression, and the challenges of targeting CSCs, with the aim of improving the clinical outcomes for patients with oral malignancies. Targeting of CSCs in head and neck cancer (HNC) represents a promising approach to improve disease outcome. Some CSC-targeted therapies have already been proven to be successful in pre-clinical studies and they are now being tested in clinical trials, mainly in combination with conventional treatment regimens. However, some studies revealed that CSCs may not be the only players that control disease relapse and progression of HNC. Further, clinical research studying a combination of therapies targeted against head and neck CSCs may provide significant advances.

SOX2 knockdown with siRNA reverses cisplatin resistance in NSCLC by regulating APE1 signaling

SOX2 is related to drug resistance in many types of cancer, including lung cancer. Herein, we investigated the role of SOX2 and its regulatory signaling in cisplatin-treated non-small-cell lung cancer (NSCLC). The effects of SOX2 on cell viability, proliferation, and apoptosis were evaluated in vitro. Western blotting, real-time quantitative PCR, immunohistochemistry, and luciferase reporter assays were used to investigate the underlying mechanism. Kaplan-Meier survival analysis and the log-rank test were used to assess the relationship between SOX2 expression and patient survival. A549/CDDP cells had marked resistance to cisplatin and stronger colony formation ability than A549 cells. The expression of SOX2 protein or mRNA in A549/CDDP was higher than that in A549. Knockdown of SOX2 in A549/CDDP-induced apoptosis by inhibiting colony formation and decreasing viability, but overexpression of SOX2 reversed these effects. Interestingly, Genomatix software predicted that the APE1 promoter has some SOX2 binding sites, while the SOX2 promoter has no APE1 binding sites. Furthermore, luciferase reporter assays proved that SOX2 could bind the promoter of APE1 in 293T cells. We further verified that SOX2 expression was not affected by shAPE1 in A549/CDDP. As expected, colony formation was obviously inhibited and apoptosis was strongly enhanced in A549/CDDP treated with SOX2 siSOX2 alone or combined with CDDP compared with control cells. Meaningfully, patients with low expression of SOX2, and even including its regulating APE1, survived longer than those with high expression of SOX2, and APE1. siSOX2 overcomes cisplatin resistance by regulating APE1 signaling, providing a new target for overcoming cisplatin resistance in NSCLC.

The Impact of Iron Chelators on the Biology of Cancer Stem Cells

Neoplastic diseases are still a major medical challenge, requiring a constant search for new therapeutic options. A serious problem of many cancers is resistance to anticancer drugs and disease progression in metastases or local recurrence. These characteristics of cancer cells may be related to the specific properties of cancer stem cells (CSC). CSCs are involved in inhibiting cells’ maturation, which is essential for maintaining their self-renewal capacity and pluripotency. They show increased expression of transcription factor proteins, which were defined as stemness-related markers. This group of proteins includes OCT4, SOX2, KLF4, Nanog, and SALL4. It has been noticed that the metabolism of cancer cells is changed, and the demand for iron is significantly increased. Iron chelators have been proven to have antitumor activity and influence the expression of stemness-related markers, thus reducing chemoresistance and the risk of tumor cell progression. This prompts further investigation of these agents as promising anticancer novel drugs. The article presents the characteristics of stemness markers and their influence on the development and course of neoplastic disease. Available iron chelators were also described, and their effects on cancer cells and expression of stemness-related markers were analyzed.

A mechanistic basis for the malignant progression of salivary gland tumors

Salivary gland tumors are diverse neoplasms, likely reflecting differences in the tissue- and cell-of-origin. 80%-90% of tumors arising in the sublingual gland (SLG) are malignant, whereas the other major glands often form benign tumors. Owing to the lack of experimental models to explore the etiology of salivary gland tumors, the cellular and molecular bases of malignancy remain unknown. Here, we generated a murine model of HRASG12V-driven salivary gland tumors amenable to examine tumor onset and malignant progression. We found that HMGA2 marks the tumor onset, and transformed-SOX2+ stem/progenitor cells expand exclusively in SLG tumors. Lineage tracing experiments showed that SLG tumor cells undergo an extensive epithelial-mesenchymal transition (EMT) and TGF-β-responding tumor cells are a source of mesenchymal tumor cells invading the surrounding stroma. This study advances our understanding of the mechanistic basis of salivary gland malignancy and may help combat this highly heterogeneous cancer.

Clinical Significance and Prognostic Value of SOX2 Protein Expression in Patients With Oral Squamous Cell Carcinoma

OBJECTIVES

Cancer stem cells are a small group of highly tumorigenic cells with the trend of self-renewal, tumor progression, metastasis, recurrence, and therapeutic resistance. SOX2 is an important cancer stem cell marker that is involved in tumorigenesis and correlated with aggressive features in various types of malignancies. The present study was aimed to investigate the expression of this biomarker in neoplastic tissues of oral squamous cell carcinoma (OSCC) to determine whether it has the potential to predict the outcomes and survival of the affected patients.

MATERIALS AND METHODS

The medical records of 73 patients diagnosed with OSCC were retrospectively studied. Clinical and pathologic features included age, sex, tumor size, histologic grade, lymph node involvement, recurrence, metastasis, and follow up. Immunohistochemical analysis for SOX2 protein expression was performed, and its correlations with clinicopathologic features were evaluated.

RESULTS

SOX2 was significantly associated with tumor size, lymph node metastasis, and patients' survival. We found no apparent correlation between SOX2 and tumor recurrence, distant metastasis, or differentiation. The multivariate analysis identifies patients' age, sex, and SOX2 expression as independent prognostic factors for overall survival.

CONCLUSION

SOX2 may worsen the prognosis and be a progressive malignant factor, which can help clinicians investigate OSCC patients' survival and plan the appropriate treatment accordingly.

Phytochemicals as Potential Chemopreventive and Chemotherapeutic Agents for Emerging Human Papillomavirus-Driven Head and Neck Cancer: Current Evidence and Future Prospects

Head and neck cancer (HNC) usually arises from squamous cells of the upper aerodigestive tract that line the mucosal surface in the head and neck region. In India, HNC is common in males, and it is the sixth most common cancer globally. Conventionally, HNC attributes to the use of alcohol or chewing tobacco. Over the past four decades, portions of human papillomavirus (HPV)-positive HNC are increasing at an alarming rate. Identification based on the etiological factors and molecular signatures demonstrates that these neoplastic lesions belong to a distinct category that differs in pathological characteristics and therapeutic response. Slow development in HNC therapeutics has resulted in a low 5-year survival rate in the last two decades. Interestingly, HPV-positive HNC has shown better outcomes following conservative treatments and immunotherapies. This raises demand to have a pre-therapy assessment of HPV status to decide the treatment strategy. Moreover, there is no HPV-specific treatment for HPV-positive HNC patients. Accumulating evidence suggests that phytochemicals are promising leads against HNC and show potential as adjuvants to chemoradiotherapy in HNC. However, only a few of these phytochemicals target HPV. The aim of the present article was to collate data on various leading phytochemicals that have shown promising results in the prevention and treatment of HNC in general and HPV-driven HNC. The review explores the possibility of using these leads against HPV-positive tumors as some of the signaling pathways are common. The review also addresses various challenges in the field that prevent their use in clinical settings.

Case Analysis of 14 Children with Malignant Rhabdoid Tumor of the Kidney

Objective

This study aims to summarize the clinical features and prognoses of the malignant rhabdoid tumor of the kidney (MRTK) in children. It further aims to analyze the high-risk factors affecting MRTK prognosis.

Methods

Clinical data from 14 children with MRTK treated in Paediatrics of Beijing Tongren Hospital from January 2010 to December 2019, along with the high-risk factors affecting prognosis, were retrospectively analyzed.

Results

There were 14 children with MRTK included in the study, with a median onset age of 13 (3–46) months. Thirteen patients had distant metastases, the most common site for metastases being inside the lung. A comprehensive treatment protocol combined with chemotherapy was mainly applied during the surgery. A surgical resection of primary tumors was performed on 13 (13/14) patients, and all 14 children received chemotherapy with ifosfamide + carboplatin + etoposide, ifosfamide + etoposide, and vincristine + pirarubicin + cyclophosphamide regimens, alternately. Three patients received radiotherapy and two received oral targeted drugs after partial response. The median follow-up was after 16.5 months (3–53 months) and the four-year overall survival (OS) was 41.8%. In children aged ≤24 months and children aged >24 months, the two-year OS was 67.2% and 100% (χ² = 108.998, P<0.05), respectively. In children with Ki 67 > 70% and children with Ki 67 < 70%, the two-year OS was 52.6% and 86.9% (χ² = 8.544, P = 0.003), respectively. In children with distant metastases and children without distant metastasis, the two-year OS was 70% and 100% (χ² = 14.239, P<0.05), respectively.

Conclusion

The most common MRTK distant metastasis site is the lung. Risk factors for poor MRTK prognoses include an age of <24 months, Ki 67 > 70%, and distant metastases.

SOX2 in cancer stemness: tumor malignancy and therapeutic potentials

Cancer stem cells (CSCs), a minor subpopulation of tumor bulks with self-renewal and seeding capacity to generate new tumors, posit a significant challenge to develop effective and long-lasting anti-cancer therapies. The emergence of drug resistance appears upon failure of chemo-/radiation therapy to eradicate the CSCs, thereby leading to CSC-mediated clinical relapse. Accumulating evidence suggests that transcription factor SOX2, a master regulator of embryonic and induced pluripotent stem cells, drives cancer stemness, fuels tumor initiation, and contributes to tumor aggressiveness through major drug resistance mechanisms like epithelial-to-mesenchymal transition, ATP-binding cassette drug transporters, anti-apoptotic and/or pro-survival signaling, lineage plasticity, and evasion of immune surveillance. Gaining a better insight and comprehensive interrogation into the mechanistic basis of SOX2-mediated generation of CSCs and treatment failure might therefore lead to new therapeutic targets involving CSC-specific anti-cancer strategies.

HPV+ve/-ve oral-tongue cancer stem cells: A potential target for relapse-free therapy

The tongue squamous cell carcinoma (TSCC) is a highly prevalent head and neck cancer often associated with tobacco and/or alcohol abuse or high-risk human papillomavirus (HR-HPV) infection. HPV positive TSCCs present a unique mechanism of tumorigenesis as compared to tobacco and alcohol-induced TSCCs and show a better prognosis when treated. The poor prognosis and/or recurrence of TSCC is due to presence of a small subpopulation of tumor-initiating tongue cancer stem cells (TCSCs) that are intrinsically resistant to conventional chemoradio-therapies enabling cancer to relapse. Therefore, targeting TCSCs may provide efficient therapeutic strategy for relapse-free survival of TSCC patients. Indeed, the development of new TCSC targeting therapeutic approaches for the successful elimination of HPV+ve/-ve TCSCs could be achieved either by targeting the self-renewal pathways, epithelial mesenchymal transition, vascular niche, nanoparticles-based therapy, induction of differentiation, chemoradio-sensitization of TCSCs or TCSC-derived exosome-based drug delivery and inhibition of HPV oncogenes or by regulating epigenetic pathways. In this review, we have discussed all these potential approaches and highlighted several important signaling pathways/networks involved in the formation and maintenance of TCSCs, which are targetable as novel therapeutic targets to sensitize/eliminate TCSCs and to improve survival of TSCC patients.

Human Papillomavirus Infection in Head and Neck Squamous Cell Carcinomas: Transcriptional Triggers and Changed Disease Patterns

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of cancers. Collectively, HNSCC ranks sixth in incidence rate worldwide. Apart from classical risk factors like tobacco and alcohol, infection of human papillomavirus (HPV) is emerging as a discrete risk factor for HNSCC. HPV-positive HNSCC represent a distinct group of diseases that differ in their clinical presentation. These lesions are well-differentiated, occur at an early age, and have better prognosis. Epidemiological studies have demonstrated a specific increase in the proportions of the HPV-positive HNSCC. HPV-positive and HPV-negative HNSCC lesions display different disease progression and clinical response. For tumorigenic-transformation, HPV essentially requires a permissive cellular environment and host cell factors for induction of viral transcription. As the spectrum of host factors is independent of HPV infection at the time of viral entry, presumably entry of HPV only selects host cells that are permissive to establishment of HPV infection. Growing evidence suggest that HPV plays a more active role in a subset of HNSCC, where they are transcriptionally-active. A variety of factors provide a favorable environment for HPV to become transcriptionally-active. The most notable are the set of transcription factors that have direct binding sites on the viral genome. As HPV does not have its own transcription machinery, it is fully dependent on host transcription factors to complete the life cycle. Here, we review and evaluate the current evidence on level of a subset of host transcription factors that influence viral genome, directly or indirectly, in HNSCC. Since many of these transcription factors can independently promote carcinogenesis, the composition of HPV permissive transcription factors in a tumor can serve as a surrogate marker of a separate molecularly-distinct class of HNSCC lesions including those cases, where HPV could not get a chance to infect but may manifest better prognosis.

Human Papillomavirus Infection in Head and Neck Squamous Cell Carcinomas: Transcriptional Triggers and Changed Disease Patterns

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of cancers. Collectively, HNSCC ranks sixth in incidence rate worldwide. Apart from classical risk factors like tobacco and alcohol, infection of human papillomavirus (HPV) is emerging as a discrete risk factor for HNSCC. HPV-positive HNSCC represent a distinct group of diseases that differ in their clinical presentation. These lesions are well-differentiated, occur at an early age, and have better prognosis. Epidemiological studies have demonstrated a specific increase in the proportions of the HPV-positive HNSCC. HPV-positive and HPV-negative HNSCC lesions display different disease progression and clinical response. For tumorigenic-transformation, HPV essentially requires a permissive cellular environment and host cell factors for induction of viral transcription. As the spectrum of host factors is independent of HPV infection at the time of viral entry, presumably entry of HPV only selects host cells that are permissive to establishment of HPV infection. Growing evidence suggest that HPV plays a more active role in a subset of HNSCC, where they are transcriptionally-active. A variety of factors provide a favorable environment for HPV to become transcriptionally-active. The most notable are the set of transcription factors that have direct binding sites on the viral genome. As HPV does not have its own transcription machinery, it is fully dependent on host transcription factors to complete the life cycle. Here, we review and evaluate the current evidence on level of a subset of host transcription factors that influence viral genome, directly or indirectly, in HNSCC. Since many of these transcription factors can independently promote carcinogenesis, the composition of HPV permissive transcription factors in a tumor can serve as a surrogate marker of a separate molecularly-distinct class of HNSCC lesions including those cases, where HPV could not get a chance to infect but may manifest better prognosis.

SOX2 and squamous cancers

SOX2 is a pleiotropic nuclear transcription factor with major roles in stem cell biology and in development. Over the last 10 years SOX2 has also been implicated as a lineage-specific oncogene, notably in squamous carcinomas but also neurological tumours, particularly glioblastoma. Squamous carcinomas (SQCs) comprise a common group of malignancies for which there are no targeted therapeutic interventions. In this article we review the molecular epidemiological and laboratory evidence linking SOX2 with squamous carcinogenesis, explore in detail the multifaceted impact of SOX2 in SQC, describe areas of uncertainty and highlight areas for potential future research.

Sox2 induces tumorigenesis and angiogenesis of early-stage esophageal squamous cell carcinoma through secretion of Suprabasin

Early stage of esophageal squamous cell carcinoma (ESCC) is known to be accompanied by angiogenesis and morphological changes of microvessels. Transcription factor Sox2 is amplified in various cancers including ESCC, but the role of Sox2 in the carcinogenesis and angiogenesis has not been determined. Hence, we aimed to investigate the role of Sox2 in the early stage of ESCC. We found that the expression of Sox2 was significantly higher in early-stage ESCC tissues than that in their adjacent normal tissues. We then established Sox2-inducible normal human esophageal squamous cell line (HetSox2) to investigate the role of Sox2 in esophageal carcinogenesis and angiogenesis in vitro. Sox2 overexpression led to increased cell proliferation and spheroid formation. The culture supernatant of Sox2-overexpressing HetSox2 induced migration and sprouting of endothelial cell line HUVEC (human umbilical vein endothelial cell). As for the mechanism, we found that the expression of secreted protein Suprabasin was directly induced by Sox2. Suprabasin enhanced proliferation of normal human esophageal squamous cells when added to the culture. Moreover, Suprabasin enhanced migration and sprouting of HUVEC cells, which were observed with the culture supernatant of Sox2-overexpressing HetSox2. This angiogenic effect of Suprabasin was abolished by inhibiting AKT phosphorylation, which suggested its dependence on AKT signaling. Finally, we showed that Suprabasin expression and the density of microvessels were significantly higher in ESCC tissues with high Sox2 expression. Our study suggested that increased Sox2 expression in esophageal squamous cells induced Suprabasin expression, and as a result initiated the carcinogenesis via increased cell proliferation and angiogenesis.

Prognostic Implication of SOX2 Expression Associated with p16 in Oropharyngeal Cancer: A Study of Consecutive Tissue Microarrays and TCGA

Simple Summary

The role of human papillomavirus (HPV) in oropharyngeal cancer (OPSCC) as a cause agent has been reported in much of the literature. As a surrogate marker, p16 immunohistochemical staining is used as the standard for classifying OPSCC, and the prognosis of p16+ OPSCC has been reported to be better than p16− OPSCC. However, it was necessary to study what is the next biomarker that could predict the prognosis after classification by p16. We assumed that SOX2 may be a potential biomarker. For each p16+ and p16− OPSCC, SOX2 was used to analyze whether the degree of expression level differed in survival and recurrence rates. The results showed that both immunohistochemical staining and mRNA expression level of SOX2 significantly affected the survival and recurrence rates of p16+ OPSCC patients in two different datasets which were constructed in differently ways. Our study presented the clinical applicability of SOX2 as a biomarker.

Abstract

For oropharyngeal squamous cell carcinoma (OPSCC), there are not enough additional robust biomarkers for subgrouping after the distinct classification using p16. As SOX2 is an emerging biomarker for cancer treatment, its clinical implication in OPSCC was evaluated using a consecutive tissue microarray (TMA) cohort consisting of 111 patients who underwent surgery as an initial treatment from May 2002 to December 2016 and 79 patients in The Cancer Genome Atlas (TCGA) dataset. In both datasets, p16+/SOX2^High (HPV+/SOX2^High in TCGA) showed the best prognosis among the four groups classified by SOX2 and p16 for 5-year overall survival (OS) and recurrence (all p < 0.05), but SOX2 did not make a significant difference in the prognosis of the p16− group. In the TMA cohort, SOX2^High was significantly correlated with response to radiotherapy and lower pathologic T classification in the p16+ group (p = 0.001). In TCGA, correlations between SOX2 and tumor stage classification or radiotherapy were not observed; however, HPV+/SOX2^High had a significantly low tumor mutation burden among the four groups (all p < 0.05). In summary, SOX2 was proven to be a potential marker to predict overall survival and recurrence in p16+ OPSCC. However, the role of SOX2 has not yet been confirmed in p16− OPSCC patients.

Advancements in Cancer Stem Cell Isolation and Characterization

Occurrence of stem cells (CSCs) in cancer is well established in last two decades. These rare cells share several properties including presence of common surface markers, stem cell markers, chemo- and radio- resistance and are highly metastatic in nature; thus, considered as valuable prognostic and therapeutic targets in cancer. However, the studies related to CSCs pave number of issues due to rare cell population and difficulties in their isolation ascribed to common stem cell marker. Various techniques including flow cytometry, laser micro-dissection, fluorescent nanodiamonds and microfluidics are used for the isolation of these rare cells. In this review, we have included the advance strategies adopted for the isolation of CSCs using above mentioned techniques. Furthermore, CSCs are primarily found in the core of the solid tumors and their microenvironment plays an important role in maintenance, self-renewal, division and tumor development. Therefore, in vivo tracking and model development become obligatory for functional studies of CSCs. Fluorescence and bioluminescence tagging has been widely used for transplantation assay and lineage tracking experiments to improve our understanding towards CSCs behaviour in their niche. Techniques such as Magnetic resonance imaging (MRI) and Positron emission tomography (PET) have proved useful for tracking of endogenous CSCs which could be helpful in their identification in clinical settings.

Functional characterization of SOX2 as an anticancer target

SOX2 is a well-characterized pluripotent factor that is essential for stem cell self-renewal, reprogramming, and homeostasis. The cellular levels of SOX2 are precisely regulated by a complicated network at the levels of transcription, post-transcription, and post-translation. In many types of human cancer, SOX2 is dysregulated due to gene amplification and protein overexpression. SOX2 overexpression is associated with poor survival of cancer patients. Mechanistically, SOX2 promotes proliferation, survival, invasion/metastasis, cancer stemness, and drug resistance. SOX2 is, therefore, an attractive anticancer target. However, little progress has been made in the efforts to discover SOX2 inhibitors, largely due to undruggable nature of SOX2 as a transcription factor. In this review, we first briefly introduced SOX2 as a transcription factor, its domain structure, normal physiological functions, and its involvement in human cancers. We next discussed its role in embryonic development and stem cell-renewal. We then mainly focused on three aspects of SOX2: (a) the regulatory mechanisms of SOX2, including how SOX2 level is regulated, and how SOX2 cross-talks with multiple signaling pathways to control growth and survival; (b) the role of SOX2 in tumorigenesis and drug resistance; and (c) current drug discovery efforts on targeting SOX2, and the future perspectives to discover specific SOX2 inhibitors for effective cancer therapy.

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.

Potential Role of DEC1 in Cervical Cancer Cells Involving Overexpression and Apoptosis

Basic helix-loop-helix (BHLH) transcription factors differentiated embryonic chondrocyte gene 1 (DEC1) and gene 2 (DEC2) regulate circadian rhythms, apoptosis, epithelial mesenchymal transition (EMT), invasions and metastases in various kinds of cancer. The stem cell markers SOX2 and c-MYC are involved in the regulation of apoptosis and poor prognosis. In cervical cancer, however, their roles are not well elucidated yet. To determine the function of these genes in human cervical cancer, we examined the expression of DEC1, DEC2, SOX2 and c-MYC in human cervical cancer tissues. In immunohistochemistry, they were strongly expressed in cancer cells compared with in non-cancerous cells. Notably, the strong rate of DEC1 and SOX2 expressions were over 80% among 20 cases. We further examined the roles of DEC1 and DEC2 in apoptosis. Human cervical cancer HeLa and SiHa cells were treated with cisplatin-HeLa cells were sensitive to apoptosis, but SiHa cells were resistant. DEC1 expression decreased in the cisplatin-treated HeLa cells, but had little effect on SiHa cells. Combination treatment of DEC1 overexpression and cisplatin inhibited apoptosis and affected SOX2 and c-MYC expressions in HeLa cells. Meanwhile, DEC2 overexpression had little effect on apoptosis and on SOX2 and c-MYC expressions. We conclude that DEC1 has anti-apoptotic effects and regulates SOX2 and c-MYC expressions on apoptosis.

Unraveling cancer lineage drivers in squamous cell carcinomas

Cancer hijacks embryonic development and adult wound repair mechanisms to fuel malignancy. Cancer frequently originates from de-regulated adult stem cells or progenitors, which are otherwise essential units for postnatal tissue remodeling and repair. Cancer genomics studies have revealed convergence of multiple cancers across organ sites, including squamous cell carcinomas (SCCs), a common group of cancers arising from the head and neck, esophagus, lung, cervix and skin. In this review, we summarize our current knowledge on the molecular drivers of SCCs, including these five major organ sites. We especially focus our discussion on lineage dependent driver genes and pathways, in the context of squamous development and stratification. We then use skin as a model to discuss the notion of field cancerization during SCC carcinogenesis, and cancer as a wound that never heals. Finally, we turn to the idea of context dependency widely observed in cancer driver genes, and outline literature support and possible explanations for their lineage specific functions. Through these discussions, we aim to provide an up-to-date summary of molecular mechanisms driving tumor plasticity in squamous cancers. Such basic knowledge will be helpful to inform the clinics for better stratifying cancer patients, revealing novel drug targets and providing effective treatment options.

SOX2 protein biochemistry in stemness, reprogramming, and cancer: the PI3K/AKT/SOX2 axis and beyond

Research of the past view years expanded our understanding of the various physiological functions the cell-fate determining transcription factor SOX2 exerts in ontogenesis, reprogramming, and cancer. However, while scientific reports featuring novel and exciting aspects of SOX2-driven biology are published in near weekly routine, investigations in the underlying protein-biochemical processes that transiently tailor SOX2 activity to situational demand are underrepresented and have not yet been comprehensively summarized. Largely unrecognizable to modern array or sequencing-based technology, various protein secondary modifications and concomitant function modulations have been reported for SOX2. The chemical modifications imposed onto SOX2 are inherently heterogeneous, comprising singular or clustered events of phosphorylation, methylation, acetylation, ubiquitination, SUMOylation, PARPylation, and O-glycosylation that reciprocally affect each other and critically impact SOX2 functionality, often in a tissue and species-specific manner. One recurring regulatory principle though is the canonical PI3K/AKT signaling axis to which SOX2 relates in various entangled, albeit not exclusive ways. Here we provide a comprehensive review of the current knowledge on SOX2 protein modifications, their proposed relationship to the PI3K/AKT pathway, and regulatory influence on SOX2 with regards to stemness, reprogramming, and cancer.

EGFR enhances the stemness and progression of oral cancer through inhibiting autophagic degradation of SOX2

Epidermal growth factor receptor (EGFR) is highly expressed in head and neck squamous cell carcinoma (HNSCC) and correlates with poor prognosis. EGFR has been demonstrated to be associated with cancer stem cell traits in HNSCC. However, the underlying molecular mechanism is far from elucidated. Here, SOX2, one of the most important stem cell markers, was identified as a binding partner and substrate of EGFR. EGFR signaling inhibition decreases SOX2 expression by promoting its autophagic degradation. Mechanistically, EGFR activation induces SOX2 phosphorylation at the Y277 site and reduces its ubiquitination, which inhibits its association with p62 and subsequent autophagic degradation. Gefitinib, an EGFR tyrosine kinase inhibitor, shows in vitro and in vivo protective effects against oral cancer cells that can be reversed through autophagy inhibition. Our study suggests that EGFR plays an important role in the development of cancer stem cells by stabilizing SOX2. Targeting EGFR in combination with conventional chemotherapy might be a promising strategy for the treatment of HNSCC through elimination of cancer stem cells.

Evaluation of the cancer stem cell marker DCLK1 in patients with lymph node metastases of head and neck cancer

BACKGROUND

Lymph node metastases are frequently detected in head and neck squamous cell carcinoma (HNSCC) patients. Little is known about biomarkers expressed in lymph node metastases or their influence on clinical outcome. Doublecortin-like kinase 1 (DCLK1) is one marker that might be associated with outcome, owing to its correlation with stem cell-like characteristics.

METHODS

We assessed the expression of DCLK1 in 74 postoperatively irradiated patients in histologically confirmed HNSCC lymph node metastases. Statistical analysis of the association with DCLK1 on clinical outcomes was performed.

RESULTS

DCLK1 was expressed in 63.5% of our patient cohort. DCLK1(+) HNSCC patients, compared with those without DCLK1 expression, showed a significantly poorer time to recurrence. Moreover, we observed a significantly poorer time to recurrence in HPV(-) HNSCC patients, and significantly shorter overall and disease-free survival rates in HPV(-) oropharyngeal cancer patients, compared with HPV(+) patients with these cancers. HPV(+) patients showed no significant differences in survival time according to DCLK1 expression. However, recurrent disease occurred in only DCLK1(+) patients. Mulitivariate analysis showed that DCLK1 expression in lymph node metastases is an independent marker for recurrence.

CONCLUSION

DCLK1 expression might be associated with poorer clinical outcomes in HNSCC patients, specifically in HPV(-) move patients. However, larger studies are required to verify our results.

Targeting cancer stem cells in squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a highly aggressive tumor and the sixth most common cancer worldwide. Current treatment strategies for HNSCC are surgery, radiotherapy, chemotherapy, immunotherapy or combinatorial therapies. However, the overall 5-year survival rate of HNSCC patients remains at about 50%. Cancer stem cells (CSCs), a small population among tumor cells, are able to self-renew and differentiate into different tumor cell types in a hierarchical manner, similar to normal tissue. In HNSCC, CSCs are proposed to be responsible for tumor initiation, progression, metastasis, drug resistance, and recurrence. In this review, we discuss the molecular and cellular characteristics of CSCs in HNSCC. We summarize current approaches used in the literature for identification of HNSCC CSCs, and mechanisms required for CSC regulation. We also highlight the role of CSCs in treatment failure and therapeutic targeting options for eliminating CSCs in HNSCC.

Physiology, Pathology and Regeneration of Salivary Glands

Salivary glands are essential structures in the oral cavity. A variety of diseases, such as cancer, autoimmune diseases, infections and physical traumas, can alter the functionality of these glands, greatly impacting the quality of life of patients. To date, no definitive therapeutic approach can compensate the impairment of salivary glands, and treatment are purely symptomatic. Understanding the cellular and molecular control of salivary glands function is, therefore, highly relevant for therapeutic purposes. In this review, we provide a starting platform for future studies in basic biology and clinical research, reporting classical ideas on salivary gland physiology and recently developed technology to guide regeneration, reconstruction and substitution of the functional organs.

The Hippo effector TAZ promotes cancer stemness by transcriptional activation of SOX2 in head neck squamous cell carcinoma

The Hippo-TAZ signaling has emerged as a fundamental regulator underlying cancer stem cells (CSCs) stemness which intricately associates with local recurrence and metastatic spreading in head neck squamous cell carcinoma (HNSCC). However, the precise downstream targets of TAZ responsible for HNSCC CSCs maintenance remain largely underexplored. Here, we identified Sex determining region Y box 2 (SOX2) as a putative downstream target of TAZ to promote CSCs maintenance and tumorigenicity in HNSCC. Both TAZ and SOX2 were significantly enriched in CSCs subpopulation (CD44+CD133+) isolated from Cal27 and Fadu cells via fluorescence-activated cell sorting. TAZ knockdown significantly reduced expression of SOX2 at both mRNA and protein levels, whereas its ectopic overexpression markedly increased its abundance in HNSCC cells. Moreover, reintroduction of ectopic SOX2 abolished, at least in part, the reduced tumorsphere formation and tumorigenicity in vivo induced by TAZ knockdown. Mechanistically, transcriptional complex formed by TAZ and TEAD4 was recruited to two binding sites in SOX2 promoter, which in turn facilitated transcription of SOX2 in HNSCC cells. In addition, the abundance of TAZ and SOX2 was positively correlated in HNSCC clinical samples, and both upregulations of TAZ and SOX2 associated with the worst survival. Taken together, our data reveal a previously unknown mechanistic linkage between TAZ and SOX2 and identify SOX2 as a direct downstream target of TAZ in modulating CSCs self-renewal and maintenance in HNSCC. These findings suggest that targeting TAZ-SOX2 axis might be a promising therapeutic strategy for HNSCC.

Practical Application of Lineage-Specific Immunohistochemistry Markers: Transcription Factors (Sometimes) Behaving Badly

CONTEXT.—

Transcription factors (TFs) are proteins that regulate gene expression and control RNA transcription from DNA. Lineage-specific TFs have increasingly been used by pathologists to determine tumor lineage, especially in the setting of metastatic tumors of unknown primary, among other uses. With experience gathered from its daily application and increasing pitfalls reported from immunohistochemical studies, these often-touted highly specific TFs are not as reliable as once thought.

OBJECTIVES.—

To summarize the established roles of many of the commonly used TFs in clinical practice and to discuss known and potential sources for error (eg, false-positivity from cross-reactivity, aberrant, and overlap "lineage-specific" expression) in their application and interpretation.

DATA SOURCES.—

Literature review and the authors' personal practice experience were used. Several examples selected from the University Health Network (Toronto, Ontario, Canada) are illustrated.

CONCLUSIONS.—

The application of TF diagnostic immunohistochemistry has enabled pathologists to better assess the lineage/origin of primary and metastatic tumors. However, the awareness of potential pitfalls is essential to avoid misdiagnosis.

Metastatic potential and prognostic significance of SOX2: A meta-analysis

BACKGROUND

SOX2 is a regulator of pluripotent cellular transcription, yet it has been recently integrated in cancer biology. The present study provides an analytic insight into the correlation of SOX2 overexpression with cancer metastasis and patient survival.

AIM

To investigate the association of SOX2 overexpression with metastasis and its implication in the prognosis of cancer patients.

METHODS

A meta-analysis was conducted including studies that compared the association of low or high SOX2 expression with lymph node metastasis (LNM) and/or distant metastasis (DM). The following data were additionally extracted: survival, including the overall survival (OS) and disease-free survival (DFS), and prevalence of high and low SOX2 expression. Odds ratios (commonly known as ORs) and their respective 95% confidence intervals (CIs) were used to investigate the association between SOX2 expression and LNM and DM, while hazard ratios (commonly known as HRs) and 95%CIs were applied to evaluate the prognostic markers.

RESULTS

In a total of 2643 patients (60.88% males), the pooled prevalence of SOX2 overexpression was 46.22% (95%CI: 39.07%-53.38%) in different types of cancer. SOX2 overexpression significantly correlated with DM (OR = 1.79, 95%CI: 1.20-3.25, P < 0.008) compared to low SOX2 expression. In subgroups analyses, a high SOX2 expression was associated with LNM in cancers of the lung, breast, and colon and associated with DM in hepatic, head and neck, and colon cancers. SOX2 overexpression was also associated with a shorter OS (HR = 1.65, 95%CI: 1.34-2.04, P < 0.001) and DFS (HR = 1.54, 95%CI: 1.14-2.08, P = 0.005).

CONCLUSION

A remarkable role of SOX2 overexpression was observed in cancer biology and metastasis. However, many questions in the regulatory pathways need to be addressed to reveal as many functional aspects as possible to tailor new targeted therapeutic strategies.

Identification of prognostic molecular biomarkers in 157 HPV-positive and HPV-negative squamous cell carcinomas of the oropharynx

The incidence of oropharyngeal squamous cell carcinoma (OPSCC) has been increasing due to high-risk HPV infection. We explored the significance of genetic alterations in HPV-positive (HPV-P) and HPV-negative (HPV-N) OPSCC patients on long-term outcome. A total of 157 cases of primary resected OPSCC diagnosed from 1978 to 2005 were subjected to a targeted exome sequencing by MSK-IMPACT™ interrogating somatic mutations in 410 cancer-related genes. Mutational profiles were correlated to recurrence and survival outcomes. OPSCC included 47% HPV-positive (HPV-P) and 53% HPV-negative (HPV-N) tumors arising in the base of tongue (BOT, 43%), palatine tonsil (30%) and soft palate (SP, 27%). HPV negative status, SP location and smoking were associated with poorer outcome. Poorer overall survival was found in NOTCH1-mutated HPV-P (p = 0.039), and in SOX2-amplified HPV-N cases (p = 0.036). Chromosomal arm gains in 8p and 8q, and 16q loss were more common in HPV-P (p = 0.005, 0.04 and 0.01, respectively), while 9p, 18q and 21q losses were more frequent in HPV-N OPSCC (p = 0.006, 0.002 and 0.01, respectively). Novel, potentially functional JAK3, MYC and EP300 intragenic deletions were found in HPV-P, and FOXP1, CDKN2A, CCND1 and RUNX1 intragenic deletions and one FGFR3 inversion were detected in HPV-N tumors. HPV-N/TP53-wild-type OPSCC harbored recurrent mutations in NOTCH1/3/4 (39%), PIK3CA, FAT1 and TERT. In comparison to their oral and laryngeal counterparts, HPV-N OPSCC were genetically distinct. In OPSCC, HPV status, tumor subsite and smoking determine outcome. Risk-stratification can be further refined based on the mutational signature, namely, NOTCH1 and SOX2 mutation status.

Combined class I histone deacetylase and mTORC1/C2 inhibition suppresses the initiation and recurrence of oral squamous cell carcinomas by repressing SOX2

Treatment of oral squamous cell carcinoma (OSCC) remains a challenge because of the lack of effective early treatment strategies and high incidence of relapse. Here, we showed that combined 4SC-202 (a novel selective class I HDAC inhibitor) and INK128 (a selective mTORC1/C2 inhibitor) treatment exhibited synergistic effects on inhibiting cell growth, sphere-forming ability, subcutaneous tumor formation and ALDH1⁺ cancer stem cells (CSCs) in OSCC. The initiation of OSCC was significantly inhibited by combined treatment in 4NQO-induced rat model. In addition, upregulated SOX2 was associated with advanced and metastatic tumors in OSCC patients and was responsible for the drug-resistance property of OSCC cells. The inhibitory effect of combined treatment on cell viability and ALDH1⁺ CSCs were attenuated by SOX2 verexpression. Furthermore, combined treatment can effectively overcome chemoresistance and inhibit the growth of recurrent OSCC in vitro and in vivo. Mechanistically, 4SC-202 and INK128 repressed SOX2 expression through miR-429/miR-1181-mediated mRNA degradation and preventing cap-dependent mRNA translation, respectively. These results suggest that combined class I histone deacetylase and mTORC1/C2 inhibition suppresses the carcinogenesis and recurrence of OSCC by repressing SOX2.

The Novel Role of SOX2 as an Early Predictor of Cancer Risk in Patients with Laryngeal Precancerous Lesions

The SOX2 gene located at 3q26 is frequently amplified and overexpressed in multiple cancers, including head and neck squamous cell carcinomas (HNSCC). The tumor-promoting activity and involvement of SOX2 in tumor progression has been extensively demonstrated, thereby emerging as a promising therapeutic target. However, the role of SOX2 in early stages of tumorigenesis and its possible contribution to malignant transformation remain unexplored. This study investigates for the first time SOX2 protein expression by immunohistochemistry and gene amplification by real-time PCR using a large series of 94 laryngeal precancerous lesions. Correlations with the histopathological classification and the risk of progression to invasive carcinoma were established. Nuclear SOX2 expression was frequently detected in 38 (40%) laryngeal dysplasias, whereas stromal cells and normal adjacent epithelia showed negative expression. SOX2 gene amplification was detected in 18 (33%) of 55 laryngeal dysplasias. Univariate Cox analysis showed that SOX2 gene amplification (p = 0.046) and protein expression (p < 0.001) but not histological grading (p = 0.432) were significantly associated with laryngeal cancer risk. In multivariate stepwise analysis including age, tobacco, histology, SOX2 gene amplification and SOX2 expression, SOX2 expression (HR = 3.531, 95% CI 1.144 to 10.904; p = 0.028) was the only significant independent predictor of laryngeal cancer development. These findings underscore the relevant role of SOX2 in early tumorigenesis and a novel clinical application of SOX2 expression as independent predictor of laryngeal cancer risk in patients with precancerous lesions beyond current WHO histological grading. Therefore, targeting SOX2 could lead to effective strategies for both cancer prevention and treatment.

AFF4 promotes tumorigenesis and tumor-initiation capacity of head and neck squamous cell carcinoma cells by regulating SOX2

Super elongation complex (SEC) controls gene transcription by releasing Pol II from pausing. Previous studies have shown that dysfunction of SEC was associated with multiple human cancers, such as leukemia and breast cancer. However, the role of SEC in head and neck squamous cell carcinoma (HNSCC) development remains largely unknown. In this study, we found expression of AF4/FMR2 family member 4 (AFF4), the core component of SEC, was upregulated dramatically in HNSCC cell lines and tumor tissues. By using siRNA-mediated depletion and overexpression of AFF4, we demonstrated AFF4 promoted proliferation, migration and invasion of HNSCC cells. Moreover, we found AFF4 enhanced the aldehyde dehydrogenase (ALDH) activity and sphere formatting activity and was required for the tumor-initiation capacity of stem-like cells in HNSCC cell lines. Mechanistically, we found the role of AFF4 in regulation of HNSCC cell behaviors was mainly mediated by sex-determining region Y box2 (SOX2), a critical regulator involved in development of several human cancers. SOX2 expression changed in parallel with AFF4 expression in response to depletion and overexpression of AFF4, respectively. More importantly, overexpression of SOX2 rescued the inhibited proliferation, migration, invasion and ALDH activity induced by knockdown of AFF4 in HNSCC cells, at least in part. Collectively, our findings indicate AFF4 may serve as a biomarker and a potential target of therapies for patients with HNSCC.

Histologic pattern of invasion and epithelial-mesenchymal phenotype predict prognosis in squamous carcinoma of the head and neck

INTRODUCTION

Disruption of E-cadherin function and increased expression of vimentin and the transcriptional oncogene, SOX2, are thought to characterize epithelial to mesenchymal transition (EMT) in HNSCC that contributes to invasive and metastatic behavior. To determine if such changes relate to prognosis or host immune response, expression of these markers and correlations with clinical characteristics, histologic worst pattern of invasion (WPOI) and tumor infiltrating lymphocytes (TIL) and survival were assessed.

METHODS

Immunohistologic expression of markers was determined in tissue microarrays from 274 previously untreated HNSCC patients. Expression was correlated with levels of TILs in microcores and WPOI in biopsy specimens. Correlations were assessed by Kruskal-Wallis testing and Spearman correlation coefficients where appropriate. Overall and relapse-free survival were analyzed with Cox proportional hazards models. Median follow up was 60.0 months.

RESULTS

Loss of E-cadherin expression was significantly associated with low or absent SOX2 expression (R = 0.433, p < 0.0001). SOX2 expression and low grade WPOI were significantly associated with favorable overall (OS) and relapse free (RFS) survival in multivariable analysis. E-cadherin expression did not correlate with TILs, however WPOI score correlated indirectly with CD4, CD8, and FoxP3 levels. When grouped by primary treatment, lower grades (1, 2) of WPOI predicted improved RFS and OS in patients treated with primary surgery but not for patients treated with chemoradiation.

CONCLUSION

The findings suggest that SOX2 expression and WPOI are significant prognostic factors and that WPOI correlates with decreased T cell infiltration. The combination of markers and TILs might be useful in selecting patients for primary surgery.

High Expression of EpCAM and Sox2 is a Positive Prognosticator of Clinical Outcome for Head and Neck Carcinoma

Locally advanced head and neck squamous cell carcinomas (HNSCC) have limited prognosis due to frequent treatment failure. Currently, TNM-classification and human papillomavirus (HPV) infection are the sole clinical prognosticators of outcome. Tumor heterogeneity and stemness based on epithelial-mesenchymal-transition reportedly associate with therapy resistance. The capacity of epithelial marker EpCAM (EpEX), stemness regulator Sox2 and mesenchymal marker vimentin to predict clinical outcome of HSNCC patients was assessed upon immunohistochemistry staining in two cohorts of HNSCC patients treated with surgery and adjuvant radio (chemo) therapy (n = 94) and primary radio (chemo) therapy (n = 94), respectively. Prognostic values with respect to overall, disease-free and disease-specific survival were assessed in uni- and multivariate cox proportional hazard models to generate integrated risk scores. EpEX, Sox2 and vimentin displayed substantial inter- and intratumoral heterogeneity. EpEX^high and Sox2^high predicted improved clinical outcome in the discovery cohort and in the HPV-negative sub-cohort. EpEX^high and Sox2^high were confirmed as prognosticators of clinical outcome in the validation cohort treated with definitive radio(chemo)therapy. Importantly, EpEX^high identified patients with improved survival within the HPV-negative subgroup of the validation cohort. Hence, Sox2^high and particularly EpEX^high have potential as tools to predict clinical performance of HNSCC patients, foremost HPV-negative cases, in the frame of molecular-guided treatment decision-making.

SOX2 Promotes Cell Proliferation and Metastasis in Triple Negative Breast Cancer

This study explored the expression, biological function and prognostic role of SOX2 in triple negative breast cancer (TNBC). Quantitative real-time PCR and immunohistochemistry were used to detect the expression of SOX2 in TNBC cell lines and clinical tissues. MTT assay, Transwell assay, flow cytometry and xenograft mouse model were used to assess the biological functions of SOX2. It was found that SOX2 was up-regulated in both TNBC cell lines and clinical tissues. High expression of SOX2 was associated with shorter overall survival and disease free survival. Moreover, inhibition of SOX2 suppressed cell proliferation and invasion, induced cell apoptosis in vitro, and suppressed tumorigenesis and metastasis in vivo. In addition, analysis of TNM stage and lymph nodes infiltration among the 237 TNBC patients by paired χ² test showed that SOX2 was inversely correlated with tumor status, our findings provided evidence that SOX2 acts as a tumor promoter in TNBC and inhibition of SOX2 could be a potential therapeutic strategy for TNBC.

SOX2 Gene Amplification and Overexpression is Linked to HPV-positive Vulvar Carcinomas

SOX2 (SRY-related HMG-box 2) belongs to the SOX gene family of high-mobility transcription factors indispensably involved in gene regulation in pluripotent stem cells and neural differentiation. SOX2 copy number increases have been frequently reported in various types of squamous cell cancer. To better understand the effect of SOX2 aberrations on vulvar cancer phenotype and patient prognosis, we analyzed SOX2 copy number changes using fluorescence in situ hybridization and SOX2 expression by immunohistochemistry in 55 squamous cell carcinomas of the vulva. SOX2 amplification was found in 20.8% of tumors; 27.3% of vulvar carcinomas showed SOX2 protein overexpression. SOX2 amplification was correlated with SOX2 overexpression in our data set (P<0.01). Amplification of the SOX2 locus was associated with high tumor grade (P<0.05) and human papillomavirus (HPV) positivity (P<0.01). SOX2-amplified tumors showed more frequently a basaloid phenotype than nonamplified carcinomas. SOX2 protein overexpression was also correlated with basaloid phenotype and positive HPV status of vulvar carcinomas (P<0.05, each). SOX2 amplification and expression were not associated with patient overall survival. In conclusion, SOX2 copy number increases are detectable in a substantial proportion of high-grade HPV-positive vulvar carcinomas with basaloid differentiation. Our study provides further evidence for different molecular alterations in HPV-positive and HPV-negative vulvar carcinomas.

Tumor microenvironment - Unknown niche with powerful therapeutic potential

Head and neck squamous cell carcinomas (HNSCC) are in a group of cancers that are the most resistant to treatment. The survival rate of HNSCC patients has been still very low since last 20 years. The existence of relationship between oncogenic and surrounding cells is probably the reason for a poor response to treatment. Fibroblasts are an important element of tumor stroma which increases tumor cells ability to proliferate. Another highly resistance, tumorigenic and metastatic cell population in tumor microenvironment are cancer initiating cells (CICs). The population of cancer initiating cells can be found regardless of differentiation status of cancer and they seem to be crucial for HNSCC development. In this review, we describe the current state of knowledge about HNSCC biological and physiological tumor microenvironment.

Salivary gland stem cells: A review of development, regeneration and cancer

Salivary glands are responsible for maintaining the health of the oral cavity and are routinely damaged by therapeutic radiation for head and neck cancer as well as by autoimmune diseases such as Sjögren's syndrome. Regenerative approaches based on the reactivation of endogenous stem cells or the transplant of exogenous stem cells hold substantial promise in restoring the structure and function of these organs to improve patient quality of life. However, these approaches have been hampered by a lack of knowledge on the identity of salivary stem cell populations and their regulators. In this review we discuss our current knowledge on salivary stem cells and their regulators during organ development, homeostasis and regeneration. As increasing evidence in other systems suggests that progenitor cells may be a source of cancer, we also review whether these same salivary stem cells may also be cancer initiating cells.

SOX2 activation predicts prognosis in patients with head and neck squamous cell carcinoma

SOX2 copy number and mRNA expression were analysed to examine the clinical significance of SOX2 activation in HNSCC. Gene expression signatures reflecting SOX2 activation were identified in an HNSCC cohort. Patients with HNSCC were classified into two subgroups according to the gene expression signature: SOX2-high and SOX2-low. The clinical significance of SOX2 activation was further validated in two independent cohorts. Moreover, clinical significance of SOX2 activation in response to radiotherapy was assessed in patients with HNSCC. The relationship between SOX2 activation and radiotherapy was validated in an in vitro experiment. Patients in the SOX2-high subgroup had a better prognosis than patients in the SOX2-low subgroup in all three patient cohorts. Results of multivariate regression analysis showed that SOX2 signature was an independent predictor of the overall survival of patients with HNSCC (hazard ratio, 1.45; 95% confidence interval, 1.09-1.92; P = 0.01). Interestingly, SOX2 activation was a predictor of therapy outcomes in patients receiving radiotherapy. Moreover, SOX2 overexpression enhanced the effect of radiotherapy in HNSCC cell lines. SOX2 activation is associated with improved prognosis of patients with HNSCC and might be used to predict which patients might benefit from radiotherapy.

Genomic and epigenetic characterization for the comparison of synchronous bilateral tongue squamous cell carcinomas-A case report

The tongue is the most common and aggressive site for tumors in the oral cavity. These tumors are usually located in the lateral border of the tongue and are often related to the use of tobacco and alcohol. Clinical management of these tumors is predominantly based on anatomic location and TNM classification. The identification of molecular signatures with ability to explain the different outcomes observed in these patients is of paramount importance to guide and help their management.

CASE PRESENTATION

we herein describe an 88-year-old woman diagnosed with synchronous bilateral tongue carcinoma. This woman did not present the traditional risk factors related to oral cancer-alcohol, tobacco, or presence of human papiloma virus (HPV). Both tumors were classified by a pathologist as pT2. This patient was submitted to surgery, 6 months later was diagnosed with cervical metastasis and in the following 2 months died. Copy number alterations and methylation status of these 2 simultaneous tumors were analyzed using array comparative genomic hybridization, multiplex ligation-dependent probe amplification, and methylation specific multiplex ligation-dependent probe amplification. In conclusion, in both tumors we identified several molecular traits usually found among oral cavity tumors and some of those have been associated with clinical outcome, reinforcing their importance to accurately establish biomarkers with clinical applicability. Specific genomic and epigenetic signatures for each of these 2 tumors were also observed allowing their molecular discrimination. The tumor of the right side of the tongue exhibited more copy number gains than the tumor of the left side. In the left side tumor less and smaller copy number alterations and more methylated genes were observed, which could be indicative of an early phase of tumor development. This case shows the molecular heterogeneity of oral cavity tumors even in the same patient and anatomic site, which could be the key to explain the different outcomes of oral tumor patients.

Modulation of SOX2 expression delineates an end-point for paclitaxel-effectiveness in breast cancer stem cells

Tumor relapse in triple negative breast cancer patients has been implicated to chemoresistant cancer stem cells (CSCs), which under favorable conditions culminate in tumor re-formation and metastasis. Hence, eradication of CSCs during systemic chemotherapy is imperative. CSCs were sorted using immuno-phenotyping and aldefluor assay. Gene expression profiling of normal breast stem cells and breast CSCs from chemo-treated patients were carried out. Silencing SOX2 was achieved by siRNA method. Mammosphere culture and wound healing assays were carried out to assess efficacy of CSCs. Microarray analysis revealed elevated expression of SOX2, ABCG2 and TWIST1, unraveling an intertwined pluripotency-chemoresistance-EMT axis. Although paclitaxel treatment led to temporary arrest of cell migration, invasiveness resumed after drug removal. The ‘twist in the tale’ was a consistently elevated expression of TWIST1, substantiating that TWIST1 can also promote stemness and chemoresistance in tumors; hence, its eradication was imperative. Silencing SOX2 increased chemo-sensitivity and diminished sphere formation, and led to TWIST1 down regulation. This study eventually established that SOX2 silencing of CSCs along with paclitaxel treatment reduced SOX2-ABCG2-TWIST1 expression, disrupted sphere forming capacity and also reduced invasiveness by retaining epithelial-like properties of the cells, thereby suggesting a more comprehensive therapy for TNBC patients in future.

Genetic and epigenetic characterization of the tumors in a patient with a tongue primary tumor, a recurrence and a pharyngoesophageal second primary tumor

Background

The choice of therapeutic modality for oral carcinoma in recurrent or second primary tumors remains controversial, as the treatment modalities available might be reduced by the treatment of the first tumor, and the overall survival is lower when compared with patients with a single or first tumor. Identifying biomarkers that predict the risk of relapse and the response to treatment is an emerging clinical issue.

Case presentation

A Caucasian 49-years-old man was treated with chemotherapy followed by chemoradiotherapy for a primary left side tongue tumor, achieving a complete response. After 49-months of follow-up, a local recurrence was diagnosed. After 3 months, a second primary tumor at the pharyngoesophageal region was detected. Genomic and epigenetic characterization of these three tumors was performed using array Comparative Genomic Hybridization, Multiplex Ligation-dependent Probe Amplification (MLPA) and Methylation Specific MLPA.

Results

The three tumors of this patient shared several imbalances in all chromosomes excluding chromosomes 9, 20 and 22, where genes related to important functional mechanisms of tumorigenesis are mapped. The shared genomic imbalances, such as losses at 1p, 2p, 3p, 4q, 5q, 6q, 7q, 8p, 10p, 11q, 12p, 12q, 13q, 15q, 16p, 16q, 17p, 17q, 18q, 19p, 19q, 21q and Xp and gains at 3q, 7q, 14q and 15q showed a common clonal origin for the diagnosed relapses.

We identified some chromosomal imbalances and genes mapped in the chromosomes 2, 3, 4, 6, 7, 11, 14, 17, 18 and 22 as putative linked to chemoradioresistance and chemoradiosensitivity. We also observed that gains in short arm of chromosomes 6, 7, 8 and 18 were acquired after treatment of the primary tumor. We identified losses of VHL gene and promoter methylation of WT1 and GATA5 genes, as predictors of relapses.

Conclusions

A common clonal origin for the diagnosed relapses was observed and we identified some putative candidate biomarkers of prognosis, relapse risk and treatment response that could guide the development of management strategies for these patients.