Identification of a subpopulation of cells with cancer stem cell properties in head and neck squamous cell carcinoma

Update on immune-based therapy strategies targeting cancer stem cells

Accumulating data reveals that tumors possess a specialized subset of cancer cells named cancer stem cells (CSCs), responsible for metastasis and recurrence of malignancies, with various properties such as self-renewal, heterogenicity, and capacity for drug resistance. Some signaling pathways or processes like Notch, epithelial to mesenchymal transition (EMT), Hedgehog (Hh), and Wnt, as well as CSCs' surface markers such as CD44, CD123, CD133, and epithelial cell adhesion molecule (EpCAM) have pivotal roles in acquiring CSCs properties. Therefore, targeting CSC-related signaling pathways and surface markers might effectively eradicate tumors and pave the way for cancer survival. Since current treatments such as chemotherapy and radiation therapy cannot eradicate all of the CSCs and tumor relapse may happen following temporary recovery, improving novel and more efficient therapeutic options to combine with current treatments is required. Immunotherapy strategies are the new therapeutic modalities with promising results in targeting CSCs. Here, we review the targeting of CSCs by immunotherapy strategies such as dendritic cell (DC) vaccines, chimeric antigen receptors (CAR)-engineered immune cells, natural killer-cell (NK-cell) therapy, monoclonal antibodies (mAbs), checkpoint inhibitors, and the use of oncolytic viruses (OVs) in pre-clinical and clinical studies. This review will mainly focus on blood malignancies but also describe solid cancers.

Cancer stem cell-derived exosome-induced metastatic cancer: An orchestra within the tumor microenvironment

Although the mechanisms as well as pathways associated with cancer stem cell (CSC) maintenance, expansion, and tumorigenicity have been extensively studied and the role of tumor cell (TC)-derived exosomes in this process is well understood, there is a paucity of research focusing specifically on the functional mechanisms of CSC-derived exosomes (CSC-Exo)/-exosomal-ncRNAs and their impact on malignancy. This shortcoming needs to be addressed, given that these vesicular and molecular components of CSCs could have a great impact on the cancer initiation, progression, and recurrence through their interaction with other key tumor microenvironment (TME) components, such as MSCs/MSC-Exo and CAFs/CAF-Exo. In particular, understanding CSCs/CSC-Exo and its crosstalk with MSCs/MSC-Exo or CAFs/CAF-Exo that are associated with the proliferation, migration, differentiation, angiogenesis, and metastasis through an enhanced process of self-renewal, chemotherapy as well as radiotherapy resistance may aid cancer treatment. This review contributes to this endeavor by summarizing the characteristic features and functional mechanisms of CSC-Exo/MSC-Exo/CAF-Exo and their mutual impact on cancer progression and therapy resistance.

Linked CD4+/CD8+ T cell neoantigen vaccination overcomes immune checkpoint blockade resistance and enables tumor regression

Therapeutic benefit to immune checkpoint blockade (ICB) is currently limited to the subset of cancers thought to possess a sufficient tumor mutational burden (TMB) to allow for the spontaneous recognition of neoantigens (NeoAg) by autologous T cells. We explored whether the response to ICB of an aggressive low-TMB squamous cell tumor could be improved through combination immunotherapy using functionally defined NeoAg as targets for endogenous CD4+ and CD8+ T cells. We found that, whereas vaccination with CD4+ or CD8+ NeoAg alone did not offer prophylactic or therapeutic immunity, vaccines containing NeoAg recognized by both subsets overcame ICB resistance and led to the eradication of large established tumors that contained a subset of PD-L1+ tumor-initiating cancer stem cells (tCSC), provided the relevant epitopes were physically linked. Therapeutic CD4+/CD8+ T cell NeoAg vaccination produced a modified tumor microenvironment (TME) with increased numbers of NeoAg-specific CD8+ T cells existing in progenitor and intermediate exhausted states enabled by combination ICB-mediated intermolecular epitope spreading. We believe that the concepts explored herein should be exploited for the development of more potent personalized cancer vaccines that can expand the range of tumors treatable with ICB.

Transglutaminase 2 Binds to the CD44v6 Cytoplasmic Domain to Stimulate CD44v6/ERK1/2 Signaling and Maintain an Aggressive Cancer Phenotype

Transglutaminase 2 (TG2) is a key cancer cell survival protein in many cancer types. As such, efforts are underway to characterize the mechanism of TG2 action. In this study, we report that TG2 stimulates CD44v6 activity to enhance cancer cell survival via a mechanism that involves formation of a TG2/CD44v6/ERK1/2 complex that activates ERK1/2 signaling to drive an aggressive cancer phenotype. TG2 and ERK1/2 bind to the CD44v6 C-terminal intracellular cytoplasmic domain to activate ERK1/2 and stimulate cell proliferation and invasion. This is the same region that binds to ERM proteins and ankyrin to activate CD44v6-dependent cell proliferation, invasion, and migration. We further show that treatment with hyaluronan (HA), the physiologic CD44v6 ligand, stimulates CD44v6 activity, as measured by ERK1/2 activation, but that this response is severely attenuated in TG2 or CD44v6 knockdown or knockout cells. Moreover, treatment with TG2 inhibitor reduces tumor growth and that is associated with reduced CD44v6 level and ERK1/2 activity, and reduced stemness and epithelial-mesenchymal transition (EMT). These changes are replicated in CD44v6 knockout cells. These findings suggest that a unique TG2/CD44v6/ERK1/2 complex leads to increased ERK1/2 activity to stimulate an aggressive cancer phenotype and stimulate tumor growth. These findings have important implications for cancer stem cell maintenance and suggest that cotargeting of TG2 and CD44v6 with specific inhibitors may be an effective anticancer treatment strategy.

IMPLICATIONS

TG2 and CD44v6 are important procancer proteins. TG2 and ERK1/2 bind to the CD44v6 C-terminal domain to form a TG2/CD44v6/ERK1/2 complex that activates ERK1/2 to stimulate the cancer phenotype.

The Role of Hedgehog Signaling Pathway in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth leading malignancy worldwide, with a poor prognosis and limited treatment options. Molecularly targeted therapies for HNSCC are still lacking. However, recent reports provide novel insights about many molecular alterations in HNSCC that may be useful in future therapies. Therefore, it is necessary to identify new biomarkers that may provide a better prediction of the disease and promising targets for personalized therapy. The poor response of HNSCC to therapy is attributed to a small population of tumor cells called cancer stem cells (CSCs). Growing evidence indicates that the Hedgehog (HH) signaling pathway plays a crucial role in the development and maintenance of head and neck tissues. The HH pathway is normally involved in embryogenesis, stem cell renewal, and tissue regeneration. However, abnormal activation of the HH pathway is also associated with carcinogenesis and CSC regulation. Overactivation of the HH pathway was observed in several tumors, including basal cell carcinoma, that are successfully treated with HH inhibitors. However, clinical studies about HH pathways in HNSCC are still rare. In this review, we summarize the current knowledge and recent advances regarding the HH pathway in HNSCC and discuss its possible implications for prognosis and future therapy.

MicroRNAs as the pivotal regulators of cisplatin resistance in head and neck cancers

Although, there is a high rate of good prognosis in early stage head and neck tumors, about half of these tumors are detected in advanced stages with poor prognosis. A combination of chemotherapy, radiotherapy, and surgery is the treatment option in head and neck cancer (HNC) patients. Although, cisplatin (CDDP) as the first-line drug has a significant role in the treatment of HNC patients, CDDP resistance can be observed in a large number of these patients. Therefore, identification of the molecular mechanisms involved in CDDP resistance can help to reduce the side effects and also provides a better therapeutic management. MicroRNAs (miRNAs) as the post-transcriptional regulators play an important role in drug resistance. Therefore, in the present review we investigated the role of miRNAs in CDDP response of head and neck tumors. It has been reported that the miRNAs exerted their roles in CDDP response by regulation of signaling pathways such as WNT, NOTCH, PI3K/AKT, TGF-β, and NF-kB as well as apoptosis, autophagy, and EMT process. The present review paves the way to suggest a non-invasive miRNA based panel marker for the prediction of CDDP response among HNC patients. Therefore, such diagnostic miRNA based panel marker reduces the CDDP side effects and improves the clinical outcomes of these patients following an efficient therapeutic management.

CLU (clusterin) promotes mitophagic degradation of MSX2 through an AKT-DNM1L/Drp1 axis to maintain SOX2-mediated stemness in oral cancer stem cells

Mitophagy regulates cancer stem cell (CSC) populations affecting tumorigenicity and malignancy in various cancer types. Here, we report that cisplatin treatment led to the activation of higher mitophagy through regulating CLU (clusterin) levels in oral CSCs. Moreover, both the gain-of-function and loss-of-function of CLU indicated its mitophagy-specific role in clearing damaged mitochondria. CLU also regulates mitochondrial fission by activating the Ser/Thr kinase AKT, which triggered phosphorylation of DNM1L/Drp1 at the serine 616 residue initiating mitochondrial fission. More importantly, we also demonstrated that CLU-mediated mitophagy positively regulates oral CSCs through mitophagic degradation of MSX2 (msh homeobox 2), preventing its nuclear translocation from suppressing SOX2 activity and subsequent inhibition of cancer stemness and self-renewal ability. However, CLU knockdown disturbed mitochondrial metabolism generating excessive mitochondrial superoxide, which improves the sensitivity to cisplatin in oral CSCs. Notably, our results showed that CLU-mediated cytoprotection relies on SOX2 expression. SOX2 inhibition through genetic (shSOX2) and pharmacological (KRX-0401) strategies reverses CLU-mediated cytoprotection, sensitizing oral CSCs toward cisplatin-mediated cell death.

Vienna Cancer Stem Cell Club (VCSCC): 20 year jubilee and future perspectives

INTRODUCTION

The Vienna Cancer Stem Cell Club (VCSCC) was launched by a group of scientists in Vienna in 2002.

AREAS COVERED

Major aims of the VCSCC are to support research on cancer stem cells (CSC) in hematopoietic malignancies and to translate CSC-related markers and targets into clinical application. A primary focus of research in the VCSCC is the leukemic stem cell (LSC). Between 2013 and 2021, members of the VCSCC established a special research program on myeloproliferative neoplasms and since 2008, members of the VCSCC run the Ludwig Boltzmann Institute for Hematology and Oncology. In all these years, the VCSCC provided a robust intellectual platform for translational hematology and LSC research in Vienna. Furthermore, the VCSCC interacts with several national and international study groups and societies in the field. Representatives of the VCSCC also organized a number of international meetings and conferences on neoplastic stem cells, including LSC, in the past 15 years, and contributed to the definition and classification of CSC/LSC and related pre-malignant and malignant conditions.

EXPERT OPINION

The VCSCC will continue to advance the field and to develop LSC-detecting and LSC-eradicating concepts through which diagnosis, prognostication, and therapy of blood cancer patients should improve.

Establishment of a Novel Anti-CD44 Variant 10 Monoclonal Antibody C44Mab-18 for Immunohistochemical Analysis against Oral Squamous Cell Carcinomas

Head and neck squamous cell carcinoma (HNSCC) is the most common type of head and neck cancer, and has been revealed as the second-highest expression of CD44 in cancers. CD44 has been investigated as a cancer stem cell marker of HNSCC and plays a critical role in tumor malignant progression. Especially, splicing variant isoforms of CD44 (CD44v) are overexpressed in cancers and considered a promising target for cancer diagnosis and therapy. We developed monoclonal antibodies (mAbs) against CD44 by immunizing mice with CD44v3-10-overexpressed PANC-1 cells. Among the established clones, C₄₄Mab-18 (IgM, kappa) reacted with CHO/CD44v3-10, but not with CHO/CD44s and parental CHO-K1 using flow cytometry. The epitope mapping using peptides that cover variant exon-encoded regions revealed that C₄₄Mab-18 recognized the border sequence between variant 10 and the constant exon 16-encoded sequence. These results suggest that C₄₄Mab-18 recognizes variant 10-containing CD44v, but not CD44s. Furthermore, C₄₄Mab-18 could recognize the human oral squamous cell carcinoma (OSCC) cell line, HSC-3, in flow cytometry. The apparent dissociation constant (K_D) of C₄₄Mab-18 for CHO/CD44v3-10 and HSC-3 was 1.6 × 10^-7 M and 1.7 × 10^-7 M, respectively. Furthermore, C₄₄Mab-18 detected CD44v3-10 but not CHO/CD44s in Western blotting, and endogenous CD44v10 in immunohistochemistry using OSCC tissues. These results indicate that C₄₄Mab-18 is useful for detecting CD44v10 in flow cytometry and immunohistochemistry.

A novel stemness classification in acute myeloid leukemia by the stemness index and the identification of cancer stem cell-related biomarkers

Background

Stem cells play an important role in acute myeloid leukemia (AML). However, their precise effect on AML tumorigenesis and progression remains unclear.

Methods

The present study aimed to characterize stem cell-related gene expression and identify stemness biomarker genes in AML. We calculated the stemness index (mRNAsi) based on transcription data using the one-class logistic regression (OCLR) algorithm for patients in the training set. According to the mRNAsi score, we performed consensus clustering and identified two stemness subgroups. Eight stemness-related genes were identified as stemness biomarkers through gene selection by three machine learning methods.

Results

We found that patients in stemness subgroup I had a poor prognosis and benefited from nilotinib, MK-2206 and axitinib treatment. In addition, the mutation profiles of these two stemness subgroups were different, which suggested that patients in different subgroups had different biological processes. There was a strong significant negative correlation between mRNAsi and the immune score (r= -0.43, p<0.001). Furthermore, we identified eight stemness-related genes that have potential to be biomarkers, including SLC43A2, CYBB, CFP, GRN, CST3, TIMP1, CFD and IGLL1. These genes, except IGLL1, had a negative correlation with mRNAsi. SLC43A2 is expected to be a potential stemness-related biomarker in AML.

Conclusion

Overall, we established a novel stemness classification using the mRNAsi score and eight stemness-related genes that may be biomarkers. Clinical decision-making should be guided by this new signature in prospective studies.

Tissue-specific cancer stem/progenitor cells: Therapeutic implications

Surgical resection, chemotherapy, and radiation are the standard therapeutic modalities for treating cancer. These approaches are intended to target the more mature and rapidly dividing cancer cells. However, they spare the relatively quiescent and intrinsically resistant cancer stem cells (CSCs) subpopulation residing within the tumor tissue. Thus, a temporary eradication is achieved and the tumor bulk tends to revert supported by CSCs' resistant features. Based on their unique expression profile, the identification, isolation, and selective targeting of CSCs hold great promise for challenging treatment failure and reducing the risk of cancer recurrence. Yet, targeting CSCs is limited mainly by the irrelevance of the utilized cancer models. A new era of targeted and personalized anti-cancer therapies has been developed with cancer patient-derived organoids (PDOs) as a tool for establishing pre-clinical tumor models. Herein, we discuss the updated and presently available tissue-specific CSC markers in five highly occurring solid tumors. Additionally, we highlight the advantage and relevance of the three-dimensional PDOs culture model as a platform for modeling cancer, evaluating the efficacy of CSC-based therapeutics, and predicting drug response in cancer patients.

Molecular signaling in cancer stem cells of tongue squamous cell carcinoma: Therapeutic implications and challenges

Head and neck squamous cell carcinoma is the seventh most common cancer worldwide with high mortality rates. Amongst oral cavity cancers, tongue carcinoma is a very common and aggressive oral cavity carcinoma. Despite the implementation of a multimodality treatment regime including surgical intervention, chemo-radiation as well as targeted therapy, tongue carcinoma shows a poor overall 5-year survival pattern, which is attributed to therapy resistance and recurrence of the disease. The presence of a rare population, i.e., cancer stem cells (CSCs) within the tumor, are involved in therapy resistance, recurrence, and distant metastasis that results in poor survival patterns. Therapeutic agents targeting CSCs have been in clinical trials, although they are unable to reach into therapy stage which is due to their failure in trials. A more detailed understanding of the CSCs is essential for identifying efficient targets. Molecular signaling pathways, which are differentially regulated in the CSCs, are one of the promising targets to manipulate the CSCs that would provide an improved outcome. In this review, we summarize the current understanding of molecular signaling associated with the maintenance and regulation of CSCs in tongue squamous cell carcinoma in order to emphasize the need of the hour to get a deeper understanding to unravel novel targets.

A Novel Anti-CD44 Variant 3 Monoclonal Antibody C44Mab-6 Was Established for Multiple Applications

Cluster of differentiation 44 (CD44) promotes tumor progression through the recruitment of growth factors and the acquisition of stemness, invasiveness, and drug resistance. CD44 has multiple isoforms including CD44 standard (CD44s) and CD44 variants (CD44v), which have common and unique functions in tumor development. Therefore, elucidating the function of each CD44 isoform in a tumor is essential for the establishment of CD44-targeting tumor therapy. We have established various anti-CD44s and anti-CD44v monoclonal antibodies (mAbs) through the immunization of CD44v3-10-overexpressed cells. In this study, we established C44Mab-6 (IgG1, kappa), which recognized the CD44 variant 3-encoded region (CD44v3), as determined via an enzyme-linked immunosorbent assay. C44Mab-6 reacted with CD44v3-10-overexpressed Chinese hamster ovary (CHO)-K1 cells (CHO/CD44v3-10) or some cancer cell lines (COLO205 and HSC-3) via flow cytometry. The apparent KD of C44Mab-6 for CHO/CD44v3-10, COLO205, and HSC-3 was 1.5 × 10-9 M, 6.3 × 10-9 M, and 1.9 × 10-9 M, respectively. C44Mab-6 could detect the CD44v3-10 in Western blotting and stained the formalin-fixed paraffin-embedded tumor sections in immunohistochemistry. These results indicate that C44Mab-6 is useful for detecting CD44v3 in various experiments and is expected for the application of tumor diagnosis and therapy.

Linked CD4 + /CD8 + T cell neoantigen vaccination overcomes immune checkpoint blockade resistance and enables tumor regression

Therapeutic benefit to immune checkpoint blockade (ICB) is currently limited to the subset of cancers thought to possess a sufficient tumor mutational burden (TMB) to allow for the spontaneous recognition of neoantigens (NeoAg) by autologous T cells. We explored whether the response of an aggressive low TMB squamous cell tumor to ICB could be improved through combination immunotherapy using functionally defined NeoAg as targets for endogenous CD4 + and CD8 + T cells. We found that, whereas vaccination with CD4 + or CD8 + NeoAg alone did not offer prophylactic or therapeutic immunity, vaccines containing NeoAg recognized by both subsets overcame ICB resistance and led to the eradication of large established tumors that contained a subset of PD-L1 + tumor-initiating cancer stem cells (tCSC), provided the relevant epitopes were physically linked. Therapeutic CD4 + /CD8 + T cell NeoAg vaccination produced a modified tumor microenvironment (TME) with increased numbers of NeoAg-specific CD8 + T cells existing in progenitor and intermediate exhausted states enabled by combination ICB-mediated intermolecular epitope spreading. The concepts explored herein should be exploited for the development of more potent personalized cancer vaccines that can expand the range of tumors treatable with ICB.

Protocol for tumor dissociation and fluorescence-activated cell sorting of human head and neck cancers

Tumors originating from the head and neck represent diverse histologies and are comprised of several cell types, including malignant cells, cancer-associated fibroblasts, endothelial cells, and immune cells. In this protocol, we describe a step-by-step approach for the dissociation of fresh human head and neck tumor specimens, followed by isolation of viable single cells using fluorescence-activated cell sorting. Our protocol facilitates the effective downstream use of techniques, including single-cell RNA sequencing and generation of three-dimensional patient-derived organoids. For complete details on the use and execution of this protocol, please refer to Puram et al. (2017)1 and Parikh et al. (2022).2.

Cancer stem cells: an insight into the development of metastatic tumors and therapy resistance

The term "cancer stem cells" (CSCs) refers to cancer cells that exhibit traits parallel to normal stem cells, namely the potential to give rise to every type of cell identified in a tumor microenvironment. It has been found that CSCs usually develops from other neoplastic cells or non-cancerous somatic cells by acquiring stemness and malignant characteristics through particular genetic modifications. A trivial number of CSCs, identified in solid and liquid cancer, can give rise to an entire tumor population with aggressive anticancer drug resistance, metastasis, and invasiveness. Besides, cancer stem cells manipulate their intrinsic and extrinsic features, regulate the metabolic pattern of the cell, adjust efflux-influx efficiency, modulate different signaling pathways, block apoptotic signals, and cause genetic and epigenetic alterations to retain their pluripotency and ability of self-renewal. Notably, to keep the cancer stem cells' ability to become malignant cells, mesenchymal stem cells, tumor-associated fibroblasts, immune cells, etc., interact with one another. Furthermore, CSCs are characterized by the expression of particular molecular markers that carry significant diagnostic and prognostic significance. Because of this, scientific research on CSCs is becoming increasingly imperative, intending to understand the traits and behavior of cancer stem cells and create more potent anticancer therapeutics to fight cancer at the CSC level. In this review, we aimed to elucidate the critical role of CSCs in the onset and spread of cancer and the characteristics of CSCs that promote severe resistance to targeted therapy.

Clonal selection parallels between normal and cancer tissues

Clonal selection and drift drive both normal tissue and cancer development. However, the biological mechanisms and environmental conditions underpinning these processes remain to be elucidated. Clonal selection models are centered in Darwinian evolutionary theory, where some clones with the fittest features are selected and populate the tissue or tumor. We suggest that different subclasses of stem cells, each of which is responsible for a distinct feature of the selection process, share common features between normal and cancer conditions. While active stem cells populate the tissue, dormant cells account for tissue replenishment/regeneration in both normal and cancerous tissues. We also discuss potential mechanisms that drive clonal drift, their interactions with clonal selection, and their similarities during normal and cancer tissue development.

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.

Development of a Novel Anti-CD44 Variant 7/8 Monoclonal Antibody, C44Mab-34, for Multiple Applications against Oral Carcinomas

Cluster of differentiation 44 (CD44) has been investigated as a cancer stem cell (CSC) marker as it plays critical roles in tumor malignant progression. The splicing variants are overexpressed in many carcinomas, especially squamous cell carcinomas, and play critical roles in the promotion of tumor metastasis, the acquisition of CSC properties, and resistance to treatments. Therefore, each CD44 variant (CD44v) function and distribution in carcinomas should be clarified for the establishment of novel tumor diagnosis and therapy. In this study, we immunized mouse with a CD44 variant (CD44v3–10) ectodomain and established various anti-CD44 monoclonal antibodies (mAbs). One of the established clones (C44Mab-34; IgG1, kappa) recognized a peptide that covers both variant 7- and variant 8-encoded regions, indicating that C44Mab-34 is a specific mAb for CD44v7/8. Moreover, C44Mab-34 reacted with CD44v3–10-overexpressed Chinese hamster ovary-K1 (CHO) cells or the oral squamous cell carcinoma (OSCC) cell line (HSC-3) by flow cytometry. The apparent KD of C44Mab-34 for CHO/CD44v3–10 and HSC-3 was 1.4 × 10−9 and 3.2 × 10−9 M, respectively. C44Mab-34 could detect CD44v3–10 in Western blotting and stained the formalin-fixed paraffin-embedded OSCC in immunohistochemistry. These results indicate that C44Mab-34 is useful for detecting CD44v7/8 in various applications and is expected to be useful in the application of OSCC diagnosis and therapy.

Epithelial-mesenchymal transition in cancer stem cells: Therapeutic implications

Cancer stem cells (CSCs) are cancer cells that possess characteristics associated with normal stem cells, specifically the ability to give rise to all cell types found in a particular cancer sample. CSCs may generate tumors through the processes of self-renewal and differentiation into multiple cell types. CSCs present in tumors are normally resistant to conventional therapy and may contribute to tumor recurrence. Tumor residuals present after therapy, with CSCs enrichment, have all the hallmarks of epithelial-mesenchymal transition (EMT). In this review, we discuss the relationship between EMT and CSCs in cancer progression and its therapeutic implications in oral squamous cell carcinoma.

Role of hypoxia and epithelial-mesenchymal transition in the formation and maintenance of oral cancer stem cells in oral squamous cell carcinomas and metastatic lymph node: An immunohistochemical analysis

Background

Inspite of having advanced treatment modalities the overall survival rate in oral squamous cell carcinoma (OSCC) remains poor. This is considered to be mainly due to local recurrence and distant metastasis. Various studies have concentrated on the role of oral cancer stem cells (OCSCs) in the progression and metastasis of OSCC. However, the role of tumor microenvironment components has been less delved into. Hence clarity on cell biology and metastatic potential OCSCs is essential for the development of more effective anti-cancer treatment.

Aim

To establish the role of OCSCs in different grades of OSCC and metastatic lymph nodes through the expression of cluster of differentiation 44 (CD44). To demonstrate and correlate the role of hypoxia and Epithelial mesenchymal transition (EMT) in the various grades and metastatic lymph nodes in the formation and maintenance of OCSCs by employing Hypoxia-inducible factor-1 Alpha (HIF 1α) and Snail respectively.

Method and Material

A total of 36 cases of OSCC, 12 from each grade and 12 normal oral mucosal tissues were included in the study. Immunohistochemical staining was performed for the demonstration of CD44, HIF1α, and Snail.

Statistics

Descriptive analysis, Chi-square, and Spearman's rank correlation were used to analyze frequency and proportion, to compare expression and correlate between lesion proper and lymph node in each group respectively.

Results

Significant expression of CD44, HIF1 α, and Snail among advancing grades of OSCC and their metastatic lymph node were observed. A positive correlation was seen between them.

Conclusions

The prognosis of OSCC can be improved by better understanding and targeting the molecules involved in the formation and maintenance of OCSCs.

Enrichment and nLC-MS/MS Analysis of Head and Neck Cancer Mucinome Glycoproteins

Mucin-domain glycoproteins expressed on cancer cell surfaces play central roles in cell adhesion, cancer progression, stem cell renewal, and immune evasion. Despite abundant evidence that mucin-domain glycoproteins are critical to the pathobiology of head and neck squamous cell carcinoma (HNSCC), our knowledge of the composition of that mucinome is grossly incomplete. Here, we utilized a catalytically inactive point mutant of the enzyme StcE (StcE^E447D) to capture mucin-domain glycoproteins in head and neck cancer cell line lysates followed by their characterization using sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE), in-gel digestion, nano-liquid chromatography-tandem mass spectrometry (nLC-MS/MS), and enrichment analyses. We demonstrate the feasibility of this workflow for the study of mucin-domain glycoproteins in HNSCC, identify a set of mucin-domain glycoproteins common to multiple HNSCC cell lines, and report a subset of mucin-domain glycoproteins that are uniquely expressed in HSC-3 cells, a cell line derived from a highly aggressive metastatic tongue squamous cell carcinoma. This effort represents the first attempt to identify mucin-domain glycoproteins in HNSCC in an untargeted, unbiased analysis, paving the way for a more comprehensive characterization of the mucinome components that mediate aggressive tumor cell phenotypes. Data associated with this study have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the data set identifier PXD029420.

Effect of ZEB1 Associated with microRNAs on Tumor Stem Cells in Head and Neck Cancer

Cancer biologists have focused on studying cancer stem cells (CSCs) because of their ability to self-renew and recapitulate tumor heterogeneity, which increases their resistance to chemotherapy and is associated with cancer relapse. Here, we used two approaches to isolate CSCs: the first involved the metabolic enzyme aldehyde dehydrogenase ALDH, and the second involved the three cell surface markers CD44, CD117, and CD133. ALDH cells showed a higher zinc finger E-box binding homeobox 1 (ZEB1) microRNA (miRNA) expression than CD44/CD117/133 triple-positive cells, which overexpressed miRNA 200c-3p: a well-known microRNA ZEB1 inhibitor. We found that ZEB1 inhibition was driven by miR-101-3p, miR-139-5p, miR-144-3p, miR-199b-5p, and miR-200c-3p and that the FaDu Cell Line inhibition occurred at the mRNA level, whereas HN13 did not affect mRNA expression but decreased protein levels. Furthermore, we demonstrated the ability of the ZEB1 inhibitor miRNAs to modulate CSC-related genes, such as TrkB, ALDH, NANOG, and HIF1A, using transfection technology. We showed that ALDH was upregulated upon ZEB1-suppressed miRNA transfection (Mann-Whitney ** p₁₀₁ = 0.009, t-test ** p₁₃₉ = 0.009, t-test ** p₁₄₄ = 0.002, and t-test *** p₁₉₉ = 0.0006). Overall, our study enabled an improved understanding of the role of ZEB1-suppressed miRNAs in CSC biology.

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.

Identity matters: cancer stem cells and tumour plasticity in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) represents frequent yet aggressive tumours that encompass complex ecosystems of stromal and neoplastic components including a dynamic population of cancer stem cells (CSCs). Recently, research in the field of CSCs has gained increased momentum owing in part to their role in tumourigenicity, metastasis, therapy resistance and relapse. We provide herein a comprehensive assessment of the latest progress in comprehending CSC plasticity, including newly discovered influencing factors and their possible application in HNSCC. We further discuss the dynamic interplay of CSCs within tumour microenvironment considering our evolving appreciation of the contribution of oral microbiota and the pressing need for relevant models depicting their features. In sum, CSCs and tumour plasticity represent an exciting and expanding battleground with great implications for cancer therapy that are only beginning to be appreciated in head and neck oncology.

Bmi-1: A master regulator of head and neck cancer stemness

Head and neck cancers are composed of a diverse group of malignancies, many of which exhibit an unacceptably low patient survival, high morbidity and poor treatment outcomes. The cancer stem cell (CSC) hypothesis provides an explanation for the substantial patient morbidity associated with treatment resistance and the high frequency of tumor recurrence/metastasis. Stem cells are a unique population of cells capable of recapitulating a heterogenous organ from a single cell, due to their capacity to self-renew and differentiate into progenitor cells. CSCs share these attributes, in addition to playing a pivotal role in cancer initiation and progression by means of their high tumorigenic potential. CSCs constitute only a small fraction of tumor cells but play a major role in tumor initiation and therapeutic evasion. The shift towards stem-like phenotype fuels many malignant features of a cancer cell and mediates resistance to conventional chemotherapy. Bmi-1 is a master regulator of stem cell self-renewal as part of the polycomb repressive complex 1 (PRC1) and has emerged as a prominent player in cancer stem cell biology. Bmi-1 expression is upregulated in CSCs, which is augmented by tumor-promoting factors and various conventional chemotherapies. Bmi-1⁺ CSCs mediate chemoresistance and metastasis. On the other hand, inhibiting Bmi-1 rescinds CSC function and re-sensitizes cancer cells to chemotherapy. Therefore, elucidating the functional role of Bmi-1 in CSC-mediated cancer progression may unveil an attractive target for mechanism-based, developmental therapeutics. In this review, we discuss the parallels in the role of Bmi-1 in stem cell biology of health and disease and explore how this can be leveraged to advance clinical treatment strategies for head and neck cancer.

Crosstalk between cancer stem cells and the tumor microenvironment drives progression of premalignant oral epithelium

Cancer stem cells (CSC) are a subpopulation of cancer cells that exhibit properties of self-renewal and differentiation and have been implicated in metastasis and treatment failures. There is mounting evidence that carcinogen-initiated mucosal epithelial stem cells acquire the CSC phenotype following exposure to environmental or infectious mutagens and are responsible for promoting the malignant transformation of premalignant (dysplastic) epithelium. CSC further contribute to the progression of dysplasia by activating signaling pathways through crosstalk with various cell populations in the tumor microenvironment. Two cell types, tumor-associated macrophages (TAM) and vascular endothelial cells (EC) nurture CSC development, support CSC stemness, and contribute to tumor progression. Despite mounting evidence implicating CSC in the initiation and progression of dysplastic oral epithelium to squamous cell carcinoma (SCC), the molecular mechanisms underlying these synergistic biological processes remain unclear. This review will examine the mechanisms that underlie the transformation of normal epithelial stem cells into CSC and the mechanistic link between CSC, TAM, and EC in the growth and the malignant conversation of dysplastic oral epithelium.

Biological effects of cancer stem cells irradiated by charged particle: a systematic review of in vitro studies

PURPOSE

The existence of cancer stem cells (CSCs) is closely related to tumor recurrence, metastasis, and resistance to chemoradiotherapy. In addition, given the unique physical and biological advantages of charged particle, we hypothesized that charged particle irradiation would produce strong killing effects on CSCs. The purpose of our systematic review is to evaluate the biological effects of CSCs irradiated by charged particle, including proliferation, invasion, migration, and changes in the molecular level.

METHODS

We searched PubMed, EMBASE, and Web of Science until 17 march 2022 according to the key words. Included studies have to be vitro studies of CSCs irradiated by charged particle. Outcomes included one or more of radiation sensitivity, proliferation, metastasis, invasion, and molecular level changes, like DNA damage after been irradiated.

RESULTS

Eighteen studies were included in the final analysis. The 18 articles include 12-carbon ion irradiation, 4-proton irradiation, 1 α-particle irradiation, 1-carbon ion combine proton irradiation.

CONCLUSION

Through the extraction and analysis of data, we came to this conclusion: CSCs have obvious radio-resistance compared with non-CSCs, and charged particle irradiation or in combination with drugs could overcome this resistance, specifically manifested in inhibiting CSCs' proliferation, invasion, migration, and causing more and harder to repair DNA double-stranded breaks (DSB) of CSCs.

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.

The glycocalyx and immune evasion in cancer

In order to establish malignant lesions, tumors must first evade their detection by immune cells. Tumors achieve this by embellishing and tailoring their glycocalyx, a network of polysaccharides and glycosylated proteins that refracts the phagocytic efforts of myeloid cells, shrouds neoantigens and other ligands from cells of the acquired immune system, and skews immune responses. The barriers imposed by the glycocalyx are biophysical and also linked to the inhibitory receptor signaling pathways of immune cells that engage tumor sialic acids as markers of healthy "self". This would explain the pressure for cancers to upregulate the synthases, transmembrane mucins, and other heavily sialylated glycoproteins involved in establishing a repulsive glycocalyx. Accordingly, individual tumor cells that are best capable of constructing a shielding glycocalyx on their surface show higher metastatic potential in immunocompetent mice. Reciprocally, therapeutics have recently been devised to edit and dismantle the glycocalyx barrier in an effort to invigorate an immune response aimed at tumor destruction. We discuss the features of the tumor-associated glycocalyx that afford immune evasion of cancers and how strategies that target this barrier may potentiate antitumor immunity.

SOX2 Promotes Radioresistance in Non-small Cell Lung Cancer by Regulating Tumor Cells Dedifferentiation

Background: Radiation therapy plays an important role in the treatment of patients with non-small cell lung cancer (NSCLC). However, the radiocurability is greatly limited because of radioresistance which leads to treatment failure, tumor recurrence, and metastasis. Cancer stem cell (CSC) has been identified as the main factor that contributes to radiation resistance. SOX2, one of the transcription factors specifically expressed in CSC, is involved in tumorigenesis, progression, and maintenance of cell stemness. But the association between SOX2 and NSCLC radioresistance is not clear now. Methods: We constructed the radiotherapy-resistant cell line of NSCLC by multiple radiotherapy treatments. Colony formation assay, western blot, and immunofluorescence were performed to detect the radiosensitivity of cells. Western blot, qRT-PCR, and sphere formation assay were used to detect CSC characteristics of cells. Wound healing assay and Transwell assay were used to determine cell migration motility. The SOX2-upregulated model and SOX2-downregulated model was constructed by lentivirus transduction. Finally, the expression and clinical relevance of SOX2 in NSCLC were investigated by bioinformatics analysis based on TCGA and GEO datasets. Results: The expression of SOX2 was increased in radioresistant cells and a trend of dedifferentiation were observed. The results of wound healing assay and Transwell assay showed that SOX2 overexpression significantly promote the migration and invasion of NSCLC cells. Mechanistically, overexpression of SOX2 enhanced radioresistance and DNA damage repair capability of parental cells, while down-regulation of SOX2 led to decreased radioresistance and DNA repair ability in radioresistant cells, all of which were related to cells dedifferentiation regulated by SOX2. In addition, bioinformatics analysis show that high expression of SOX2 was strongly associated with the progression and poor prognosis of patients with NSCLC. Conclusions: Our study revealed that SOX2 regulates radiotherapy resistance in NSCLC via promoting cell dedifferentiation. Therefore, SOX2 may be a promising therapeutic target for overcoming radioresistance in NSCLC, providing a new perspective to improve the curative effect.

Response to primary chemoradiotherapy of locally advanced oropharyngeal carcinoma is determined by the degree of cytotoxic T cell infiltration within tumor cell aggregates

Background

Effective anti-tumor immune responses are mediated by T cells and require organized, spatially coordinated interactions within the tumor microenvironment (TME). Understanding coordinated T-cell-behavior and deciphering mechanisms of radiotherapy resistance mediated by tumor stem cells will advance risk stratification of oropharyngeal cancer (OPSCC) patients treated with primary chemoradiotherapy (RCTx).

Methods

To determine the role of CD8 T cells (CTL) and tumor stem cells for response to RCTx, we employed multiplex immunofluorescence stains on pre-treatment biopsy specimens from 86 advanced OPSCC patients and correlated these quantitative data with clinical parameters. Multiplex stains were analyzed at the single-cell level using QuPath and spatial coordination of immune cells within the TME was explored using the R-package Spatstat.

Results

Our observations demonstrate that a strong CTL-infiltration into the epithelial tumor compartment (HR for overall survival, OS: 0.35; p<0.001) and the expression of PD-L1 on CTL (HR: 0.36; p<0.001) were both associated with a significantly better response and survival upon RCTx. As expected, p16 expression was a strong predictor of improved OS (HR: 0.38; p=0.002) and correlated with overall CTL infiltration (r: 0.358, p<0.001). By contrast, tumor cell proliferative activity, expression of the tumor stem cell marker CD271 and overall CTL infiltration, regardless of the affected compartment, were not associated with response or survival.

Conclusion

In this study, we could demonstrate the clinical relevance of the spatial organization and the phenotype of CD8 T cells within the TME. In particular, we found that the infiltration of CD8 T cells specifically into the tumor cell compartment was an independent predictive marker for response to chemoradiotherapy, which was strongly associated with p16 expression. Meanwhile, tumor cell proliferation and the expression of stem cell markers showed no independent prognostic effect for patients with primary RCTx and thus requires further study.

LINC01296 promotes cancer stemness traits in oral carcinomas by sponging miR-143

Background/purpose

Emerging evidence has shown that various failures in cancer therapy, such as drug resistance, metastasis, and cancer relapse are attributed to cancer stem cells (CSCs). Also, growing attention has been paid to the regulation of non-coding RNAs in cancer stemness. Here, we aimed to investigate the contribution of LINC01296 in the modulation of oral CSCs.

Materials and methods

The phenotypic assays including migration, invasion, and colony-forming abilities were carried out in CSCs of two types of oral cancer cells (SAS and GNM) following the knockdown of LINC01296. In addition, the percentage of cells expressing stemness marker, ALDH1, and drug resistance marker, ABCG2, was examined as well as the self-renewal capacity after silencing of LINC01296. Moreover, a luciferase reporter was used to validate the direct interaction between LINC01296 and miR-143.

Results

Our results showed that LINC01296 was significantly overexpressed in oral cancer tissues and positively correlated with stemness markers. The phenotypic and flow cytometry assays demonstrated that suppression of LINC01296 reduced the aggressiveness, cancer stemness features, and colony-forming and self-renewal abilities in oral CSCs. Furthermore, we demonstrated that LINC01296 may enhance cancer stemness features through suppression of the effect of miR-143.

Conclusion

Silencing of LINC01296 may be a promising direction for oral cancer therapy by reducing cancer stemness via regulation of miR-143.

Cancer Stem Cells and Their Therapeutic Usage

Cancer stem cells (CSC) have unique characteristics which include self-renewal, multi-directional differentiation capacity, quiescence/dormancy, and tumor-forming capability. These characteristics are referred to as the "stemness" properties. Tumor microenvironment contributes to CSC survival, function, and remaining them in an undifferentiated state. CSCs can form malignant tumors with heterogeneous phenotypes mediated by the tumor microenvironment. Therefore, the crosstalk between CSCs and tumor microenvironment can modulate tumor heterogeneity. CSCs play a crucial role in several biological processes, epithelial-mesenchymal transition (EMT), autophagy, and cellular stress response. In this chapter, we focused characteristics of cancer stem cells, reprogramming strategies cells into CSCs, and then we highlighted the contribution of CSCs to therapy resistance and cancer relapse and their potential of therapeutic targeting of CSCs.

Loss of Epidermal Homeostasis Underlies the Development of Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) is one of the most common skin cancers. To develop targeted therapies for SCC, a comprehensive understanding of the disease through a systems approach is required. Here, we have collated and analyzed the literature on SCC and pathways that maintain skin homeostasis. Since, the loss of the Notch and the overactivation of the Wnt pathways in the epidermis cause SCC, we focused on these two pathways. We found that the two pathways are critical in maintaining epidermal homeostasis. Further, we found that the cancer stem cell (CSC) marker CD44 causes the transcription of SOX2, another CSC marker of SCC, activates the Wnt pathway, and blocks the Notch pathway. Similarly, the Wnt pathway causes the transcription of CD44 and SOX2 and blocks the Notch pathway. In this paper, we have discussed how the notch and the Wnt pathways affect epidermal homeostasis and the three CSCs (CD44, SOX2, and LGR6) affect the two pathways, linking the CSCs with epidermal homeostasis.

Cancer cell targeting by CAR-T cells: A matter of stemness

Chimeric antigen receptor (CAR)-T cell therapy represents one of the most innovative immunotherapy approaches. The encouraging results achieved by CAR-T cell therapy in hematological disorders paved the way for the employment of CAR engineered T cells in different types of solid tumors. This adoptive cell therapy represents a selective and efficacious approach to eradicate tumors through the recognition of tumor-associated antigens (TAAs). Binding of engineered CAR-T cells to TAAs provokes the release of several cytokines, granzyme, and perforin that ultimately lead to cancer cells elimination and patient's immune system boosting. Within the tumor mass a subpopulation of cancer cells, known as cancer stem cells (CSCs), plays a crucial role in drug resistance, tumor progression, and metastasis. CAR-T cell therapy has indeed been exploited to target CSCs specific antigens as an effective strategy for tumor heterogeneity disruption. Nevertheless, a barrier to the efficacy of CAR-T cell-based therapy is represented by the poor persistence of CAR-T cells into the hostile milieu of the CSCs niche, the development of resistance to single targeting antigen, changes in tumor and T cell metabolism, and the onset of severe adverse effects. CSCs resistance is corroborated by the presence of an immunosuppressive tumor microenvironment (TME), which includes stromal cells, cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), and immune cells. The relationship between TME components and CSCs dampens the efficacy of CAR-T cell therapy. To overcome this challenge, the double strategy based on the use of CAR-T cell therapy in combination with chemotherapy could be crucial to evade immunosuppressive TME. Here, we summarize challenges and limitations of CAR-T cell therapy targeting CSCs, with particular emphasis on the role of TME and T cell metabolic demands.

Reciprocal interplays between MicroRNAs and pluripotency transcription factors in dictating stemness features in human cancers

The interplay between microRNAs (miRNAs) and pluripotency transcription factors (TFs) orchestrates the acquisition of cancer stem cell (CSC) features during the course of malignant transformation, rendering them essential cancer cell dependencies and therapeutic vulnerabilities. In this review, we discuss emerging themes in tumor heterogeneity, including the clonal evolution and the CSC models and their implications in resistance to cancer therapies, and then provide thorough coverage on the roles played by key TFs in maintaining normal and malignant stem cell pluripotency and plasticity. In addition, we discuss the reciprocal interactions between miRNAs and MYC, OCT4, NANOG, SOX2, and KLF4 pluripotency TFs and their contributions to tumorigenesis. We provide our view on the potential to interfere with key miRNA-TF networks through the use of RNA-based therapeutics as single agents or in combination with other therapeutic strategies, to abrogate the CSC state and render tumor cells more responsive to standard and targeted therapies.

Cancer Metastasis and Treatment Resistance: Mechanistic Insights and Therapeutic Targeting of Cancer Stem Cells and the Tumor Microenvironment

Cancer metastasis and treatment resistance are the main causes of treatment failure and cancer-related deaths. Their underlying mechanisms remain to be fully elucidated and have been attributed to the presence of cancer stem cells (CSCs)-a small population of highly tumorigenic cancer cells with pluripotency and self-renewal properties, at the apex of a cellular hierarchy. CSCs drive metastasis and treatment resistance and are sustained by a dynamic tumor microenvironment (TME). Numerous pathways mediate communication between CSCs and/or the surrounding TME. These include a paracrine renin-angiotensin system and its convergent signaling pathways, the immune system, and other signaling pathways including the Notch, Wnt/β-catenin, and Sonic Hedgehog pathways. Appreciation of the mechanisms underlying metastasis and treatment resistance, and the pathways that regulate CSCs and the TME, is essential for developing a durable treatment for cancer. Pre-clinical and clinical studies exploring single-point modulation of the pathways regulating CSCs and the surrounding TME, have yielded partial and sometimes negative results. This may be explained by the presence of uninhibited alternative signaling pathways. An effective treatment of cancer may require a multi-target strategy with multi-step inhibition of signaling pathways that regulate CSCs and the TME, in lieu of the long-standing pursuit of a 'silver-bullet' single-target approach.

Squamous–columnar junction of Von Ebner’s glands may be a significant origin of squamous cell carcinomas in the base of the tongue

Objectives

The histological origin of base of the tongue (BOT) carcinomas is still elusive, and most studies have been focusing on the lingual tonsil. In this study, we sought to identify the existence of the squamous–columnar junction (SCJ) in the human Von Ebner’s glandular duct and explored the potential of that in forming squamous cell carcinomas in BOT.

Materials and methods

The specific genomes of BOT carcinoma were acquired and screened out by The Cancer Genome Atlas (TCGA) database analysis. The 4-nitroquinoline-1-oxide (4-NQO)-treated mouse model was used to explore the transformation of SCJ during cancerization. We used immunohistochemistry to confirm the characteristics of SCJ in human Von Ebner’s gland, which were further compared with those in the anus and cervix.

Results

The SCJ in the human Von Ebner’s glandular duct was found to be similar to that of the cervix and anus. The transformation zone in the 4-NQO-treated mouse model had a multilayered epithelium structure similar to that of HPV16-transgenic mice. In human, the transformation zone of Von Ebner’s gland is also similar to that of the cervix and anus.

Conclusion

It is the first time that the existence of SCJ in the opening of the human Von Ebner’s glandular duct was confirmed. The SCJ of Von Ebner’s glands may be a significant origin of squamous cell carcinomas in BOT.

Hematopoietic and Chronic Myeloid Leukemia Stem Cells: Multi-Stability versus Lineage Restriction

There is compelling evidence to support the view that the cell-of-origin for chronic myeloid leukemia is a hematopoietic stem cell. Unlike normal hematopoietic stem cells, the progeny of the leukemia stem cells are predominantly neutrophils during the disease chronic phase and there is a mild anemia. The hallmark oncogene for chronic myeloid leukemia is the BCR-ABLp210 fusion gene. Various studies have excluded a role for BCR-ABLp210 expression in maintaining the population of leukemia stem cells. Studies of BCR-ABLp210 expression in embryonal stem cells that were differentiated into hematopoietic stem cells and of the expression in transgenic mice have revealed that BCR-ABLp210 is able to veer hematopoietic stem and progenitor cells towards a myeloid fate. For the transgenic mice, global changes to the epigenetic landscape were observed. In chronic myeloid leukemia, the ability of the leukemia stem cells to choose from the many fates that are available to normal hematopoietic stem cells appears to be deregulated by BCR-ABLp210 and changes to the epigenome are also important. Even so, we still do not have a precise picture as to why neutrophils are abundantly produced in chronic myeloid leukemia.

[Metabolic Tumor Imaging in Head and Neck Oncology]

Metabolic Tumor Imaging in Head and Neck Oncology Abstract. Fluorodeoxyglucose with position emission tomography combined with CT or MRI (FDG-PET) has become an important diagnostic and staging method in head and neck squamous cell carcinoma. Some regard FDG-PET merely as a tool able of displaying cancer cells as bright spots on imaging. However, quantification of FDG uptake can be used as a surrogate marker for tumor aggressiveness and predict tumor response before (chemo)-radiation. The FDG uptake of the primary tumor can also predict surgical outcome measures such as depth of invasion, occult nodal metastasis, or bone invasion for oral cancer and/or organ preservation in hypopharyngeal cancer.

Involvement of the p53-p16/RB pathway control mechanism in early-stage carcinogenesis in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma develops through a heterogeneous process involving human papillomavirus infection, smoking, and alcohol consumption. A comprehensive genomic analysis of head and neck squamous cell carcinomas to date has identified a few single driver gene mutations, the most frequent of which involve TP53 and CDKN2A/p16. To investigate the involvement of the tumorigenesis mechanism in early-stage carcinogenesis, HPV-derived genomes E6 and E7, which are carcinogens, and stem/progenitor-associated, polycomb (PcG) genes Bmi1 and TERT were induced into human stromal cells and immortalized as the head and neck squamous cell carcinoma model. We found that Bmi1 suppressed both the p16INK4a and p16/Rb-p53 pathway cross-talks. The E7 group showed that endogenous p53 is highly expressed and eludes chromosome number aberration, even on long-term observation. Bmi1 was predominantly expressed in early head and neck squamous cell carcinoma, and PcG was essential in early cancer development. Additionally, TP53 whole exon analysis revealed categories useful for estimating malignant potential, such as poor prognosis and high recurrence at the transection site. Therefore, understanding the p53-p16/RB pathway in head and neck squamous cell carcinoma is an essential factor to elucidate the early carcinogenesis of head and neck squamous cell carcinoma.

Global research trends and hotspots on glioma stem cells

Background

Glioma stem cells (GSCs) are a sub-population of cancer stem cells with capacity of self-renewal and differentiation. Accumulated evidence has revealed that GSCs were shown to contribute to gliomagenesis, distant metastasis as well as the resistance to radiotherapy and chemotherapy. As a result, GSCs were regarded as a promising therapeutic target in human glioma. The purpose of our study is to identify current state and hotspots of GSCs research by analyzing scientific publications through bibliometric methods.

Methods

All relevant publications on GSCs during 2003-2021 were extracted from the Science Citation Index Expanded of Web of Science Core Collection (WoSCC), and related information was collected and analyzed using Microsoft Excel 2016, GraphPad Prism 8 and VOSviewer software.

Results

A total of 4990 papers were included. The United States accounted for the largest number of publications (1852), the second average citations per item (ACI) value (67.54) as well as the highest H-index (157). Cancer Research was the most influential journal in this field. The most contributive institution was League of European Research Universities. RICH JN was the author with the most publications (109) and the highest H-index (59). All studies were clustered into 3 groups: “glioma stem cell properties”, “cell biological properties” and “oncology therapy”. The keywords “identification”, “CD133” and “side population” appeared earlier with the smaller average appearing years (AAY), and the keywords”radiotherapy” and “chemotherapy” had the latest AAY. The analysis of top cited articles showed that “temozolomide”, “epithelial-mesenchymal transition”, and “immunotherapy” emerged as new focused issues.

Conclusion

There has been a growing number of researches on GSCs. The United States has always been a leading player in this domain. In general, the research focus has gradually shifted from basic cellular biology to the solutions of clinical concerns. “Temozolomide resistance”, “epithelial-mesenchymal transition”, and “immunotherapy” should be given more attention in the future.

Aqueous synthesis and self-assembly of bioactive and thermo-responsive HA-b-ELP bioconjugates

The design of synthetic (bio)macromolecules that combine biocompatibility, self-assembly and bioactivity properties at the molecular level is an intense field of research for biomedical applications such as (nano)medicine. In this contribution, we have designed and synthesized a library of bioactive and thermo-responsive bioconjugates from elastin-like polypeptides (ELPs) and hyaluronic acid (HA) in order to access bioactive self-assembled nanoparticles. These were prepared by a simple synthetic and purification strategy, compatible with the requirements for biological applications and industrial scale-up. A series of 9 HA-b-ELP bioconjugates with different compositions and block lengths was synthesized under aqueous conditions by strain-promoted azide-alkyne cycloaddition (SPAAC), avoiding the use of catalysts, co-reactants and organic solvents, and isolated by a simple centrifugation step. An extensive physico-chemical study was then performed on the whole library of bioconjugates in an attempt to establish structure-property relationships. In particular, the determination of the critical conditions for thermally driven self-assembly was carried out upon temperature (CMT) and concentration (CMC) gradients, leading to a phase diagram for each of these bioconjugates. These parameters and the size of nanoparticles were found to depend on the chemical composition of the bioconjugates, namely on the respective size of individual blocks. Understanding the mechanism underlying this dependency is a real asset for designing more effective experiments: with key criteria defined (e.g. concentration, temperature, salinity, and biological target), the composition of the best candidates can be rationalized. In particular, four of the bioconjugates (HA_4.6k-ELPn80 or n100 and HA_24k-ELPn80 or n100) were found to self-assemble into well-defined spherical core-shell nanoparticles, with a negative surface charge due to the HA block exposed at the surface, a hydrodynamic diameter between 40 and 200 nm under physiological conditions and a good stability over time at 37 °C. We therefore propose here a versatile and simple design of smart, controllable, and bioactive nanoparticles that present different behaviors depending on the diblocks' composition.

Lessons to cancer from studies of leukemia and hematopoiesis

The starting point to describing the origin and nature of any cancer must be knowledge about how the normal counterpart tissue develops. New principles to the nature of hematopoietic stem cells have arisen in recent years. In particular, hematopoietic stem cells can “choose” a cell lineage directly from a spectrum of the end-cell options, and are, therefore, a heterogeneous population of lineage affiliated/biased cells. These cells remain versatile because the developmental trajectories of hematopoietic stem and progenitor cells are broad. From studies of human acute myeloid leukemia, leukemia is also a hierarchy of maturing or partially maturing cells that are sustained by leukemia stem cells at the apex. This cellular hierarchy model has been extended to a wide variety of human solid tumors, by the identification of cancer stem cells, and is termed the cancer stem cell model. At least, two genomic insults are needed for cancer, as seen from studies of human childhood acute lymphoblastic leukemia. There are signature mutations for some leukemia’s and some relate to a transcription factor that guides the cell lineage of developing hematopoietic stem/progenitor cells. Similarly, some oncogenes restrict the fate of leukemia stem cells and their offspring to a single maturation pathway. In this case, a loss of intrinsic stem cell versatility seems to be a property of leukemia stem cells. To provide more effective cures for leukemia, there is the need to find ways to eliminate leukemia stem cells.

The lipid rafts in cancer stem cell: a target to eradicate cancer

Cancer stem cells (CSCs) are a subpopulation of cancer cells with stem cell properties that sustain cancers, which may be responsible for cancer metastasis or recurrence. Lipid rafts are cholesterol- and sphingolipid-enriched microdomains in the plasma membrane that mediate various intracellular signaling. The occurrence and progression of cancer are closely related to lipid rafts. Emerging evidence indicates that lipid raft levels are significantly enriched in CSCs compared to cancer cells and that most CSC markers such as CD24, CD44, and CD133 are located in lipid rafts. Furthermore, lipid rafts play an essential role in CSCs, specifically in CSC self-renewal, epithelial-mesenchymal transition, drug resistance, and CSC niche. Therefore, lipid rafts are critical regulatory platforms for CSCs and promising therapeutic targets for cancer therapy.