Cancer stem cells accountability in progression of head and neck squamous cell carcinoma: the most recent trends!

Onco-Ontogeny of Squamous Cell Cancer of the First Pharyngeal Arch Derivatives

Head and neck squamous cell carcinoma (H&NSCC) is an anatomic, biological, and genetic complex disease. It involves more than 1000 genes implied in its oncogenesis; for this review, we limit our search and description to the genes implied in the onco-ontogeny of the derivates from the first pharyngeal arch during embryo development. They can be grouped as transcription factors and signaling molecules (that act as growth factors that bind to receptors). Finally, we propose the term embryo-oncogenesis to refer to the activation, reactivation, and use of the genes involved in the embryo's development during the oncogenesis or malignant tumor invasion and metastasis events as part of an onco-ontogenic inverse process.

Can Immunoexpression of Cancer Stem Cell Markers Prognosticate Tongue Squamous Cell Carcinoma? A Systematic Review and Meta-Analysis

The objective was to evaluate the association of the immunoexpression of cancer stem cell (CSC) markers with clinicopathological and survival outcomes in tongue squamous cell carcinoma (TSCC) patients. This systematic review and meta-analysis [PROSPERO (CRD42021226791)] included observational studies that compared the association of clinicopathological and survival outcomes with CSC immunoexpression in TSCC patients. Pooled odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (CI) were used as outcome measures. Six studies identified the association with three surface markers (c-MET, STAT3, CD44) and four transcription markers (NANOG, OCT4, BMI, SOX2). The odds of early-stage presentation were 41% (OR = 0.59, 95% CI 0.42-0.83) and 75% (OR = 0.25; 95% CI 0.14-0.45) lower in CSC and SOX2 immuno-positive cases than immuno-negative cases, respectively. The odds of well-differentiated tumors in transcription marker immuno-positive cases were 45% lower compared to immuno-negative cases (OR = 0.55, 95% CI 0.32-0.96). The odds of positive lymph nodes were 2.01 times higher in CSC immuno-positive cases compared to immuno-negative cases (OR = 2.01, 95% CI 1.11-3.65). Mortality in immuno-positive cases was 121% higher than that in immuno-negative cases (HR = 2.21; 95% CI 1.16-4.21). Advanced tumor staging and grading, lymph node metastasis, and mortality were significantly associated with positive immunoexpression of CSC markers.

Circulating Tumor Cell Detection during Neoadjuvant Chemotherapy to Predict Early Response in Locally Advanced Oropharyngeal Cancers: A Prospective Pilot Study

Patients with locally advanced oropharyngeal carcinoma treated with neoadjuvant chemotherapy are reassessed both radiologically and clinically to adapt their treatment after the first cycle. However, some responders show early tumor progression after adjuvant radiotherapy. This cohort study evaluated circulating tumor cells (CTCs) from a population of locally advanced oropharyngeal carcinoma patients treated with docetaxel, cisplatin, and 5-fluorouracil (DCF) induction chemotherapy or DCF with a modified dose and fractioned administration. The counts and phenotypes of CTCs were assessed at baseline and at day 21 of treatment, after isolation using the RosetteSep^TM technique based on negative enrichment. At baseline, 6 out of 21 patients had CTCs (28.6%). On day 21, 5 out of 11 patients had CTCs (41.6%). There was no significant difference in the overall and progression-free survival between patients with or without CTCs at baseline (p = 0.44 and 0.78) or day 21 (p = 0.88 and 0.5). Out of the 11 patients tested at day 21, 4 had a positive variation of CTCs (33%). Patients with a positive variation of CTCs display a lower overall survival. Our findings suggest that the variation in the number of CTCs would be a better guide to the management of treatment, with possible early changes in treatment strategy.

Role of cancer stem cells in head-and-neck squamous cell carcinoma - A systematic review

Targeting cancer stem cell (CSC) subpopulation within the tumor remains an obstacle for specific therapy in head-and-neck squamous cell carcinoma (HNSCC). Few studies in the literature describe a panel of stem cell makers, however a distinct panel has not been put forth. This systematic review aims to enhance the knowledge of additional markers to accurately relate their expression to tumorigenesis, metastasis, and therapy resistance. Databases, including PubMed, Google Scholar, Ebsco, and Science Direct, were searched from 2010 to 2017 using various combinations of the following keywords: “Stem cell markers in HNSCC” and “chemoresistance and radioresistence in HNSCC.” Original experimental studies (both in vitro and in vivo) published in English considering stem cell markers in HNSCC, were considered and included. We excluded articles on tumors other than HNSCC, reviews, editorial letters, book chapters, opinions, and abstracts from the analyses. Forty-two articles were included, in which 13 types of stem cell markers were identified. The most commonly expressed CSC markers were CD44, aldehyde dehydrogenase, and CD133, which were responsible for tumorigenesis, self-renewal, and therapy resistance, whereas NANOG, SOX-2, and OCT-4 were involved in metastasis and invasion. Identification of an accurate panel of CSC markers is the need of the hour as nonspecificity of the current markers poses a problem. Further studies with a large sample size would help validate the role of these CSC markers in HNSCC. These CSC proteins can be developed as therapeutic targets for HNSCC therapy, making future treatment modality more specific and effective.

Synthesis and Characterization of Salinomycin-Loaded High-Density Lipoprotein and Its Effects on Cervical Cancer Cells and Cervical Cancer Stem Cells

Background

Cervical cancer stem cells (CCSCs), a small part of tumor population, are one of the important reasons for metastasis and recurrence of cervical cancer. Targeting CCSCs may be an effective way to eliminate tumors. Salinomycin (Sal) has been proved to be an effective anticancer drug in many studies, especially for cancer stem cells (CSCs). However, the cytotoxicity of salinomycin limits its further research as an anticancer drug. High-density lipoprotein (HDL) nanoparticles are an excellent drug carrier, which can reduce the toxicity of Sal, have a certain targeting effect and improve the clinical benefit of Sal.

Methods

Salinomycin-loaded high-density lipoprotein (S-HDL) was synthesized and characterized by various analytical techniques. CD44^highCD24^low CCSCs were isolated from HeLa cells by magnetic separation. The uptake of HDL nanoparticles was observed by laser confocal microscopy, and the effect of S-HDL on the proliferation of CCCs and CCSCs was detected by cell viability analysis. Genome-wide analysis was used to analyze the effects of S-HDL on the biological processes of CCCs and then cell apoptosis, cell cycle and cell migration were selected for verification.

Results

S-HDL had a particle size of 38.98 ± 1.78 nm and an encapsulation efficiency of 50.73 ± 4.29%. Cell uptake analysis showed that HDL nanoparticles could enhance the drug uptake of CCCs and CCSCs and may target CCCs and CCSCs. In cell viability analysis, CCCs and CCSCs showed high sensitivity to S-HDL. S-HDL can more efficiently prevent CCSCs from developing tumorspheres than Sal in tumorsphere formation study. S-HDL had stronger ability to induce cell cycle arrest, promote cell apoptosis and inhibit cell migration compared with free Sal, which was consistent with the results of Genome Wide analysis.

Conclusion

S-HDL can effectively target and eliminate CCCs and CCSCs, which is a potential drug for the treatment of cervical cancer.

Wnt Signaling: A Potential Therapeutic Target in Head and Neck Squamous Cell Carcinoma

Cellular maintenance and development are two fundamental mechanisms regulated by the canonical Wnt signaling pathway. Wnt/beta-catenin signaling pathway controls a myriad of cellular processes that are essential for normal cell functioning. Cell cycle progression, differentiation, fate determination, and migration are generally orchestrated by canonical Wnt signaling. Altered Wnt/beta-catenin signaling has been considered a promoting event for different types of cancers and the oncogenic potential of Wnt signaling have been discussed in many cancer types, including breast, colon, pancreatic as well as head and neck. Furthermore, Wnt signaling is critical for the maintenance and stemness of both the normal as well as cancer stem cells. This review sheds new light on Wnt signaling and explains how it can regulate normal physiological processes and curtail the development of cancer. It depicts the vital functions of Wnt signaling in the stem cell growth and differentiation by focusing on current druggable targets that have been ascribed by recent studies. Thus, Wnt signaling pathway retains a tremendous potential in eradicating head and neck squamous cell carcinoma.

Therapy resistance mediated by cancer stem cells

Cancer stem cells (CSC) possess abilities generally associated with embryonic or adult stem cells, especially self-renewal and differentiation. The CSC model assumes that this subpopulation of cells sustains malignant growth, which suggests a hierarchical organization of tumors in which CSCs are on top and responsible for the generation of intratumoral heterogeneity. Effective tumor therapy requires the eradication of CSC as they can support regrowth of the tumor resulting in recurrence. However, eradication of CSC is difficult because they frequently are therapy resistant. Therapy resistance is mediated by the acquisition of dormancy, increased DNA repair and drug efflux capacity, decreased apoptosis as well as the interaction between CSC and their supporting microenvironment, the CSC niche. This review highlights the role of CSC in chemo- and radiotherapy resistance as well as possible ways to overcome CSC mediated therapy resistance.

Immunolocalization of Cancer Stem Cells Marker ALDH1 and its Association with Tumor Budding in Oral Squamous Cell Carcinoma

Tumor budding is a prognostic marker for oral squamous cell carcinoma (OSCC) characterized by the presence of isolated or small clusters of neoplastic cells at the tumor invasive front. Aldehyde dehydrogenase-1 (ALDH1) is associated with tumorigenesis, linked to treatment resistance and shown to identify cancer stem cells (CSC)-like cells. This study aimed to evaluate the expression of ALDH1 and its association with tumor budding in OSCC. Immunohistochemistry was employed in 163 OSCC samples to identify pancytokeratin (AE1/AE3) and ALDH1. While pancytokeratin (AE1/AE3) identified squamous tumor buds, the CSC-like cells were identified using ALDH1. A Chi square test was used to evaluate association between ALDH1 expression and tumor budding, while McNemar's test was used to identify differences in ALDH1 expression between the budding area and the area outside the budding. A positive expression of ALDH1 was observed in 47.24% of the samples and in 70% of anatomic locations affected. No association was observed between ALDH1 expression and tumor budding (p > 0.05). In tumors with high-intensity tumor budding, ALDH1 expression was higher in the budding area than in the area outside the budding (p < 0.05). The finding that tumor bud cells in OSCC show phenotypic characteristics of CSC-like cells reinforces the relevance of tumor budding in determining the biological behavior of this malignant neoplasm. Moreover, the presence of CSC-like cells in nearly half of evaluated samples of OSCC and in most of the affected anatomic locations is in accordance with the CSC model of oral carcinogenesis.

Preferential targeting of cancer stem cells in the radiosensitizing effect of ABT-737 on HNSCC

Head and neck squamous cell carcinomas (HNSCC) are common human malignancies with poor clinical outcomes. The 5-year survival rates for patients with advanced stage HNSCC have not changed appreciably in the past few decades, underscoring a dire need for improved therapeutic options. HNSCC is frequently characterized by overexpression of anti-apoptotic Bcl-2 family members. Increased levels of these anti-apoptotic proteins have been associated with radio- and chemoresistance and poor clinical outcome. The aim of this study was to evaluate combined effects of radiation and ABT-737, a BH3-mimetic molecule, in HNSCC. Although ABT-737, as a single agent, was largely ineffective at promoting HNSCC cell death, we found that combining ABT-737 and radiation induced strong synergistic apoptosis in HNSCC cell lines and delayed tumoral growth in vivo. Moreover, we demonstrated for the first time that ABT-737, alone or in combination with radiation, can efficiently eliminate cancer stem cells (CSCs). Altogether, our results indicate that therapy targeting anti-apoptotic Bcl-2 family members could be a highly effective potential adjuvant to radiotherapy capable of targeting CSCs in HNSCC and therefore overcoming cancer recurrence and metastasis.

Cancer stem cells: An insight

Cancer stem cells (CSCs) have the ability to self-renew and are present in most tissues including breast, brain, lung, head and neck, prostates, testis, ovary, esophagus, colon and liver. Their origin is yet to be discovered though a series of hypotheses have been proposed in this regard. CSCs play a role in not only the creation of cancer but also its evolution, metastasis and recurrence. CSCs have an important role in cancer therapy and the resistance toward chemotherapeutic agents. This article reviews the characteristics of CSCs in terms of origin, methods of isolation and cancer therapy.

Expression of stem cell markers in oral cavity and oropharynx squamous cell carcinoma

OBJECTIVES

The aim of this study was to analyze the expression of CD24, CD44, CD133, ALDH1, CD29 (integrin-β1), and Ki-67 in squamous cell carcinoma of the oral cavity and oropharynx.

STUDY DESIGN

Fifty-two tumors and 21 metastatic lymph nodes were evaluated by using immunohistochemistry.

RESULTS

Seven of 52 cases (13.5%) showed positive cytoplasmic staining of aldehyde dehydrogenase 1; integrin-β1 was expressed in 45 of 50 cases (90%); 30 of 52 cases (57.7%) had positive membranous staining of CD44; CD24 was expressed in 44 of 50 cases (88%); and three of 52 cases (5.8%) stained positively for membranous CD133. Median proliferation rate, measured by Ki-67, was 37.1% for tumors. Five-year cancer-specific survival rates for the CD44-negative and CD44-positive groups were 74% and 38%, respectively, although this difference did not reach statistical significance (P = .052).

CONCLUSIONS

Our study demonstrated the expression of putative stem cell markers in squamous cell carcinoma of the oral cavity and oropharynx, with participation of CD44-positive cells in association with poor survival outcome.

Downregulated expression of miRNA-149 promotes apoptosis in side population cells sorted from the TSU prostate cancer cell line

The objective of the present study was to identify prostate cancer stem cells and determine the effects of modulating specific miRNAs on prostate CSC proliferation and apoptosis. We applied flow cytometry sorting of side population cells to cultures of prostate cancer cell lines (TSU, DU145, PC-3 and LNCaP). The proportion of SP cells in the TSU line was 1.60±0.40% (mean ± SD), while that of the DU145, PC-3 and LNCaP lines was 0.60±0.05, 0.80±0.05 and 0.60±0.20%, respectively. Because the proportion of SP cells derived from TSU cells is greater, these cells were selected to sort side population cells and non-side population cells. The stem-like properties of SP cells had been identified by in vivo and in vitro experiments, and the related study was published. RNA was extracted from the SP cells and non-SP cells and analyzed using miRNA microarray technology. Fifty-three miRNAs with significant differences in their expression were detected in total. Furthermore, 20 of these miRNAs were validated by qPCR. We found that hsa-miR‑149 expression in SP cells and non-SP cells was significantly different; hsa-miR-149 was significantly upregulated in SP cells. By constructing a vector for lentiviral infection, we found that the downregulation of hsa-miR-149 leads to a reduction in proliferation, an increase in apoptosis, and a significant reduction in the colony formation potential, thus, inhibiting tumor growth in vivo of SP cells from the TSU cell line. The present study will provide new avenues toward understanding the function of prostate cancer stem cells (PCSCs) in tumorigenicity and metastasis.

Promising Druggable Target in Head and Neck Squamous Cell Carcinoma: Wnt Signaling

Canonical Wnt signaling pathway, also known as Wnt/β-catenin signaling pathway, is a crucial mechanism for cellular maintenance and development. It regulates cell cycle progression, apoptosis, proliferation, migration, and differentiation. Dysregulation of this pathway correlates with oncogenesis in various tissues including breast, colon, pancreatic as well as head and neck cancers. Furthermore, the canonical Wnt signaling pathway has also been described as one of the critical signaling pathways for regulation of normal stem cells as well as cancer cells with stem cell-like features, termed cancer stem cells (CSC). In this review, we will briefly describe the basic mechanisms of Wnt signaling pathway and its crucial roles in the normal regulation of cellular processes as well as in the development of cancer. Next, we will highlight the roles of canonical Wnt signaling pathway in the regulation of CSC properties namely self-renewal, differentiation, metastasis, and drug resistance abilities, particularly in head and neck squamous cell carcinoma. Finally, we will examine the findings of several recent studies which explore druggable targets in the canonical Wnt signaling pathway which could be valuable to improve the treatment outcome for head and neck cancer.

Stem cell therapy: A novel treatment approach for oral mucosal lesions

Stem cells have enormous potential to alleviate sufferings of many diseases that currently have no effective therapy. The research in this field is growing at an exponential rate. Stem cells are master cells that have specialized capability for self-renewal, potency and capability to differentiate to many cell types. At present, the adult mesenchymal stem cells are being used in the head and neck region for orofacial regeneration (including enamel, dentin, pulp and alveolar bone) in lieu of their proliferative and regenerative properties, their use in the treatment of oral mucosal lesions is still in budding stages. Moreover, there is scanty literature available regarding role of stem cell therapy in the treatment of commonly seen oral mucosal lesions like oral submucous fibrosis, oral lichen planus, oral ulcers and oral mucositis. The present review will focus on the current knowledge about the role of stem cell therapies in oral mucosal lesions and could facilitate new advancements in this area (articles were obtained from electronic media like PubMed, EBSCO, Cochrane and Medline etc., from year 2000 to 2014 to review the role of stem cell therapy in oral mucosal lesions).

Hypoxia-shaped vascular niche for cancer stem cells

The tumour microenvironment, long considered as determining cancer development, still offers research fields to define hallmarks of cancer. An early key-step, the “angiogenic switch”, allows tumour growth. Pathologic angiogenesis is a cancer hallmark as it features results of tumour-specific properties that can be summarised as a response to hypoxia. The hypoxic state occurs when the tumour mass reaches a volume sufficient not to permit oxygen diffusion inside the tumour centre. Thus tumour cells turn on adaptation mechanisms to the low pO₂ level, inducing biochemical responses in terms of cytokines/chemokines/receptors and consequently recruitment of specific cell types, as well as cell-selection inside the tumour. Moreover, these changes are orchestrated by the microRNA balance strongly reflecting the hypoxic milieu and mediating the cross-talk between endothelial and tumour cells. MicroRNAs control of the endothelial precursor-vascular settings shapes the niche for selection of cancer stem cells.

Immunologically augmented skin flap as a novel dendritic cell vaccine against head and neck cancer in a rat model

Local recurrence is a major clinical issue following surgical resection in head and neck cancer, and the dissemination and lymph node metastasis of minimal residual disease is relatively difficult to treat due to the lack of suitable therapeutic approaches. In the present study, we developed and evaluated a novel immunotherapy using a skin flap transfer treated with sensitized dendritic cells (DC), termed the “immuno-flap,” in a rat tumor model. After the local round area of skin was resected, SCC-158 cells (a rat head and neck cancer cell line) were inoculated into the muscle surface; lastly, the groin skin flap injected with mature DC was overlaid. Two weeks after the second DC injection, systemic immunological reactions and tumor size were measured. The DC-treated group showed a significant reduction in tumor size compared with the control. Although the induction of CTL activity in spleen cells was marginal, Th1 cytokines such as interleukin-2 and interferon-γ were elevated in the DC-treated group. These results suggest that a novel immunotherapy based on the immuno-flap method has the potential for clinical application to prevent the local recurrence of head and neck cancer patients.