Cancer stem cells and oral cancer: insights into molecular mechanisms and therapeutic approaches

Tumor relapse and treatment failure are unfortunately common events for cancer patients, thus often rendering cancer an uncurable disease. Cancer stem cells (CSCs) are a subset of cancer cells endowed with tumor-initiating and self-renewal capacity, as well as with high adaptive abilities. Altogether, these features contribute to CSC survival after one or multiple therapeutic approaches, thus leading to treatment failure and tumor progression/relapse. Thus, elucidating the molecular mechanisms associated with stemness-driven resistance is crucial for the development of more effective drugs and durable responses. This review will highlight the mechanisms exploited by CSCs to overcome different therapeutic strategies, from chemo- and radiotherapies to targeted therapies and immunotherapies, shedding light on their plasticity as an insidious trait responsible for their adaptation/escape. Finally, novel CSC-specific approaches will be described, providing evidence of their preclinical and clinical applications.

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Oral Cancer Stem Cells: Therapeutic Implications and Challenges

Frontiers in Oral Health ◽

10.3389/froh.2021.685236 ◽

2021 ◽

Vol 2 ◽

Author(s):

Linah A. Shahoumi

Keyword(s):

Stem Cells ◽

Squamous Cell Carcinoma ◽

Oral Cancer ◽

Cancer Stem Cells ◽

Cell Carcinoma ◽

Head And Neck ◽

Squamous Cell ◽

Molecular Mechanisms ◽

Current Evidence ◽

Cancer Management

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.

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Molecular Mechanisms Underlying the Functions of Cellular Markers Associated with the Phenotype of Cancer Stem Cells

Current Stem Cell Research & Therapy ◽

10.2174/1574888x13666180821154752 ◽

2019 ◽

Vol 14 (5) ◽

pp. 405-420 ◽

Cited By ~ 2

Author(s):

Eduardo Alvarado-Ortiz ◽

Miguel Á. Sarabia-Sánchez ◽

Alejandro García-Carrancá

Keyword(s):

Stem Cells ◽

Cancer Stem Cells ◽

Molecular Mechanisms ◽

Tumor Biology ◽

Molecular Tools ◽

Recent Past ◽

Functional Roles ◽

Cellular Population ◽

Cellular Markers ◽

A Minor

Cancer Stem Cells (CSC) generally constitute a minor cellular population within tumors that exhibits some capacities of normal Stem Cells (SC). The existence of CSC, able to self-renew and differentiate, influences central aspects of tumor biology, in part because they can continue tumor growth, give rise to metastasis, and acquire drug and radioresistance, which open new avenues for therapeutics. It is well known that SC constantly interacts with their niche, which includes mesenchymal cells, extracellular ligands, and the Extra Cellular Matrix (ECM). These interactions regularly lead to homeostasis and maintenance of SC characteristics. However, the exact participation of each of these components for CSC maintenance is not clear, as they appear to be context- or cell-specific. In the recent past, surface cellular markers have been fundamental molecular tools for identifying CSC and distinguishing them from other tumor cells. Importantly, some of these cellular markers have been shown to possess functional roles that affect central aspects of CSC. Likewise, some of these markers can participate in regulating the interaction of CSC with their niche, particularly the ECM. We focused this review on the molecular mechanisms of surface cellular markers commonly employed to identify CSC, highlighting the signaling pathways and mechanisms involved in CSC-ECM interactions, through each of the cellular markers commonly used in the study of CSC, such as CD44, CD133, CD49f, CD24, CXCR4, and LGR5. Their presence does not necessarily implicate them in CSC biology.

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The molecular mechanisms of curcumin’s inhibitory effects on cancer stem cells

Journal of Cellular Biochemistry ◽

10.1002/jcb.27757 ◽

2018 ◽

Vol 120 (4) ◽

pp. 4739-4747 ◽

Cited By ~ 12

Author(s):

Elham Zendehdel ◽

Elham Abdollahi ◽

Amir Abbas Momtazi‐Borojeni ◽

Mitra Korani ◽

Seyedeh Hoda Alavizadeh ◽

...

Keyword(s):

Stem Cells ◽

Cancer Stem Cells ◽

Molecular Mechanisms ◽

Inhibitory Effects

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Current Strategies for Identification of Glioma Stem Cells: Adequate or Unsatisfactory?

Journal of Oncology ◽

10.1155/2012/376894 ◽

2012 ◽

Vol 2012 ◽

pp. 1-10 ◽

Cited By ~ 44

Author(s):

Paola Brescia ◽

Cristina Richichi ◽

Giuliana Pelicci

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Cancer Stem Cells ◽

Large Scale ◽

Molecular Mechanisms ◽

Cell Phenotype ◽

Multiple Tumor ◽

Early Results ◽

Tumorigenic Potential ◽

Tumor Types

Cancer stem cells (CSCs) were isolated in multiple tumor types, including human glioblastomas, and although the presence of surface markers selectively expressed on CSCs can be used to isolate them, no marker/pattern of markers are sufficiently robust to definitively identify stem cells in tumors. Several markers were evaluated for their prognostic value with promising early results, however none of them was proven to be clinically useful in large-scale studies, leading to outstanding efforts to identify new markers. Given the heterogeneity of human glioblastomas further investigations are necessary to identify both cancer stem cell-specific markers and the molecular mechanisms sustaining the tumorigenic potential of these cells to develop tailored treatments. Markers for glioblastoma stem cells such as CD133, CD15, integrin-α6, L1CAM might be informative to identify these cells but cannot be conclusively linked to a stem cell phenotype. Overlap of expression, functional state and morphology of different subpopulations lead to carefully consider the techniques employed so far to isolate these cells. Due to a dearth of methods and markers reliably identifying the candidate cancer stem cells, the isolation/enrichment of cancer stem cells to be therapeutically targeted remains a major challenge.

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Hepatic Cancer Stem Cells: Molecular Mechanisms, Therapeutic Implications, and Circulating Biomarkers

Cancers ◽

10.3390/cancers13184550 ◽

2021 ◽

Vol 13 (18) ◽

pp. 4550

Author(s):

Laura Gramantieri ◽

Catia Giovannini ◽

Fabrizia Suzzi ◽

Ilaria Leoni ◽

Francesca Fornari

Keyword(s):

Stem Cells ◽

Cancer Stem Cells ◽

Anticancer Agents ◽

Tumor Heterogeneity ◽

Molecular Mechanisms ◽

Driving Forces ◽

Predictive Biomarkers ◽

Molecular Classification ◽

Circulating Biomarkers ◽

Therapeutic Implications

Hepatocellular carcinoma (HCC) is one of the deadliest cancers. HCC is associated with multiple risk factors and is characterized by a marked tumor heterogeneity that makes its molecular classification difficult to apply in the clinics. The lack of circulating biomarkers for the diagnosis, prognosis, and prediction of response to treatments further undermines the possibility of developing personalized therapies. Accumulating evidence affirms the involvement of cancer stem cells (CSCs) in tumor heterogeneity, recurrence, and drug resistance. Owing to the contribution of CSCs to treatment failure, there is an urgent need to develop novel therapeutic strategies targeting, not only the tumor bulk, but also the CSC subpopulation. Clarification of the molecular mechanisms influencing CSC properties, and the identification of their functional roles in tumor progression, may facilitate the discovery of novel CSC-based therapeutic targets to be used alone, or in combination with current anticancer agents, for the treatment of HCC. Here, we review the driving forces behind the regulation of liver CSCs and their therapeutic implications. Additionally, we provide data on their possible exploitation as prognostic and predictive biomarkers in patients with HCC.

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Stem Cell Concept in Thyroid Cancer

Integrative Journal of Medical Sciences ◽

10.15342/ijms.7.199 ◽

2020 ◽

Vol 7 ◽

Author(s):

Cihan Zamur ◽

Uğur Topal ◽

Harun Özdemir ◽

Serdar Altınay

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Thyroid Cancer ◽

Thyroid Gland ◽

Cancer Stem Cells ◽

Molecular Mechanisms ◽

Clinical Results ◽

Cell Populations ◽

Cellular Origin ◽

Rare Cells

The most frequently diagnosed endocrine cancer, which causes more deaths than any other endocrine cancer, is thyroid cancer. Cancer stem cells are rare cells found in tumors that can regenerate themselves, phenotypically leads to various tumor cell populations and trigger tumorigenesis. Cancer stem cells have been identified in many cancers, including thyroid cancer. Having an understanding of the molecular mechanisms which control the biology of cancer stem cells and the disease processes will help us in designing more rational targeted therapies for aggressive thyroid cancers. In this review, we aimed to present the current accepted knowledge about thyroid stem cells, information regarding the cellular origin of thyroid cancer stem cells, and the clinical results of cancer stem cells present in the thyroid gland.

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Characterization of CD133+/CD44+ human prostate cancer stem cells with ATR-FTIR spectroscopy

The Analyst ◽

10.1039/c9an00093c ◽

2019 ◽

Vol 144 (6) ◽

pp. 2138-2149 ◽

Cited By ~ 4

Author(s):

Günnur Güler ◽

Ummu Guven ◽

Gulperi Oktem

Keyword(s):

Prostate Cancer ◽

Stem Cells ◽

Cancer Stem Cells ◽

Ftir Spectroscopy ◽

Molecular Mechanisms ◽

Human Prostate ◽

Human Prostate Cancer ◽

Prostate Cancer Stem Cells

Molecular mechanisms and features of prostate cancer stem cells, which are crucial for improving target specific therapies, were elucidated with ATR-FTIR spectroscopy.

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Counteracting Chemoresistance with Metformin in Breast Cancers: Targeting Cancer Stem Cells

Cancers ◽

10.3390/cancers12092482 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2482

Author(s):

Samson Mathews Samuel ◽

Elizabeth Varghese ◽

Lenka Koklesová ◽

Alena Líšková ◽

Peter Kubatka ◽

...

Keyword(s):

Breast Cancer ◽

Stem Cells ◽

Cancer Stem Cells ◽

Molecular Mechanisms ◽

Epithelial Mesenchymal Transition ◽

Acquired Resistance ◽

Breast Cancers ◽

Intrinsic Resistance ◽

Mesenchymal Transition ◽

Cancer Breast

Despite the leaps and bounds in achieving success in the management and treatment of breast cancers through surgery, chemotherapy, and radiotherapy, breast cancer remains the most frequently occurring cancer in women and the most common cause of cancer-related deaths among women. Systemic therapeutic approaches, such as chemotherapy, although beneficial in treating and curing breast cancer subjects with localized breast tumors, tend to fail in metastatic cases of the disease due to (a) an acquired resistance to the chemotherapeutic drug and (b) the development of intrinsic resistance to therapy. The existence of cancer stem cells (CSCs) plays a crucial role in both acquired and intrinsic chemoresistance. CSCs are less abundant than terminally differentiated cancer cells and confer chemoresistance through a unique altered metabolism and capability to evade the immune response system. Furthermore, CSCs possess active DNA repair systems, transporters that support multidrug resistance (MDR), advanced detoxification processes, and the ability to self-renew and differentiate into tumor progenitor cells, thereby supporting cancer invasion, metastasis, and recurrence/relapse. Hence, current research is focusing on targeting CSCs to overcome resistance and improve the efficacy of the treatment and management of breast cancer. Studies revealed that metformin (1, 1-dimethylbiguanide), a widely used anti-hyperglycemic agent, sensitizes tumor response to various chemotherapeutic drugs. Metformin selectively targets CSCs and improves the hypoxic microenvironment, suppresses the tumor metastasis and inflammation, as well as regulates the metabolic programming, induces apoptosis, and reverses epithelial–mesenchymal transition and MDR. Here, we discuss cancer (breast cancer) and chemoresistance, the molecular mechanisms of chemoresistance in breast cancers, and metformin as a chemo-sensitizing/re-sensitizing agent, with a particular focus on breast CSCs as a critical contributing factor to acquired and intrinsic chemoresistance. The review outlines the prospects and directions for a better understanding and re-purposing of metformin as an anti-cancer/chemo-sensitizing drug in the treatment of breast cancer. It intends to provide a rationale for the use of metformin as a combinatory therapy in a clinical setting.

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