Therapeutic Targeting of Cancer Stem Cells in Lung, Head and Neck, and Bladder Cancers

Resistance to cancer therapy remains a significant obstacle in treating patients with various solid malignancies. Exposure to current chemotherapeutics and targeted agents invariably leads to therapy resistance, heralding the need for novel agents. Cancer stem cells (CSCs)—a subpopulation of tumor cells with capacities for self-renewal and multi-lineage differentiation—represent a pool of therapeutically resistant cells. CSCs often share physical and molecular characteristics with the stem cell population of the human body. It remains challenging to selectively target CSCs in therapeutically resistant tumors. The generation of CSCs and induction of therapeutic resistance can be attributed to several deregulated critical growth regulatory signaling pathways such as WNT/β-catenin, Notch, Hippo, and Hedgehog. Beyond growth regulatory pathways, CSCs also change the tumor microenvironment and resist endogenous immune attack. Thus, CSCs can interfere with each stage of carcinogenesis from malignant transformation to the onset of metastasis to tumor recurrence. A thorough review of novel targeted agents to act against CSCs is fundamental for advancing cancer treatment in the setting of both intrinsic and acquired resistance.

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PIK3C3 Inhibition Promotes Sensitivity to Colon Cancer Therapy by Inhibiting Cancer Stem Cells

Cancers ◽

10.3390/cancers13092168 ◽

2021 ◽

Vol 13 (9) ◽

pp. 2168

Author(s):

Balawant Kumar ◽

Rizwan Ahmad ◽

Swagat Sharma ◽

Saiprasad Gowrikumar ◽

Mark Primeaux ◽

...

Keyword(s):

Stem Cells ◽

Colon Cancer ◽

Cancer Therapy ◽

Cancer Stem Cells ◽

Side Population ◽

Therapy Resistance ◽

Fluorescent Reporter ◽

Combination Treatments ◽

Gsk 3Β ◽

Resistance To Chemotherapy

Background: Despite recent advances in therapies, resistance to chemotherapy remains a critical problem in the clinical management of colorectal cancer (CRC). Cancer stem cells (CSCs) play a central role in therapy resistance. Thus, elimination of CSCs is crucial for effective CRC therapy; however, such strategies are limited. Autophagy promotes resistance to cancer therapy; however, whether autophagy protects CSCs to promote resistance to CRC-therapy is not well understood. Moreover, specific and potent autophagy inhibitors are warranted as clinical trials with hydroxychloroquine have not been successful. Methods: Colon cancer cells and tumoroids were used. Fluorescent reporter-based analysis of autophagy flux, spheroid and side population (SP) culture, and qPCR were done. We synthesized 36-077, a potent inhibitor of PIK3C3/VPS34 kinase, to inhibit autophagy. Combination treatments were done using 5-fluorouracil (5-FU) and 36-077. Results: The 5-FU treatment induced autophagy only in a subset of the treated colon cancer. These autophagy-enriched cells also showed increased expression of CSC markers. Co-treatment with 36-077 significantly improved efficacy of the 5-FU treatment. Mechanistic studies revealed that combination therapy inhibited GSK-3β/Wnt/β-catenin signaling to inhibit CSC population. Conclusion: Autophagy promotes resistance to CRC-therapy by specifically promoting GSK-3β/Wnt/β-catenin signaling to promote CSC survival, and 36-077, a PIK3C3/VPS34 inhibitor, helps promote efficacy of CRC therapy.

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Genome-wide CRISPR-Cas9 screen identified KLF11 as a druggable suppressor for sarcoma cancer stem cells

Science Advances ◽

10.1126/sciadv.abe3445 ◽

2021 ◽

Vol 7 (5) ◽

pp. eabe3445

Author(s):

Yicun Wang ◽

Jinhui Wu ◽

Hui Chen ◽

Yang Yang ◽

Chengwu Xiao ◽

...

Keyword(s):

Stem Cells ◽

Cancer Stem Cells ◽

Negative Feedback ◽

Direct Interaction ◽

Therapy Resistance ◽

Negative Regulator ◽

Chemotherapy Response ◽

Genome Wide

Cancer stem cells (CSCs) are involved in tumorigenesis, recurrence, and therapy resistance. To identify critical regulators of sarcoma CSCs, we performed a reporter-based genome-wide CRISPR-Cas9 screen and uncovered Kruppel-like factor 11 (KLF11) as top candidate. In vitro and in vivo functional annotation defined a negative role of KLF11 in CSCs. Mechanistically, KLF11 and YAP/TEAD bound to adjacent DNA sites along with direct interaction. KLF11 recruited SIN3A/HDAC to suppress the transcriptional output of YAP/TEAD, which, in turn, promoted KLF11 transcription, forming a negative feedback loop. However, in CSCs, this negative feedback was lost because of epigenetic silence of KLF11, causing sustained YAP activation. Low KLF11 was associated with poor prognosis and chemotherapy response in patients with sarcoma. Pharmacological activation of KLF11 by thiazolidinedione effectively restored chemotherapy response. Collectively, our study identifies KLF11 as a negative regulator in sarcoma CSCs and potential therapeutic target.

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The molecular mechanism and regulatory pathways of cancer stem cells

Cancer Translational Medicine ◽

10.4103/2395-3977.192932 ◽

2016 ◽

Vol 2 (5) ◽

pp. 147 ◽

Cited By ~ 2

Author(s):

Yanyang Tu ◽

Zhen Wang ◽

Hongwei Yang ◽

Xin Wang ◽

Liang Wang ◽

...

Keyword(s):

Stem Cells ◽

Cancer Stem Cells ◽

Molecular Mechanism ◽

Regulatory Pathways

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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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Cancer stem cells - important players in tumor therapy resistance

FEBS Journal ◽

10.1111/febs.13023 ◽

2014 ◽

Vol 281 (21) ◽

pp. 4779-4791 ◽

Cited By ~ 145

Author(s):

Selcuk Colak ◽

Jan P. Medema

Keyword(s):

Stem Cells ◽

Cancer Stem Cells ◽

Tumor Therapy ◽

Therapy Resistance

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Proteomic Analysis of Breast Cancer Resistance to the Anticancer Drug RH1 Reveals the Importance of Cancer Stem Cells

Cancers ◽

10.3390/cancers11070972 ◽

2019 ◽

Vol 11 (7) ◽

pp. 972

Author(s):

Dalius Kuciauskas ◽

Nadezda Dreize ◽

Marija Ger ◽

Algirdas Kaupinis ◽

Kristijonas Zemaitis ◽

...

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Stem Cells ◽

Stem Cell ◽

Cancer Stem Cells ◽

Cancer Cells ◽

Proteomic Analysis ◽

Acquired Resistance ◽

Cancer Resistance ◽

Resistant Cells

Antitumor drug resistance remains a major challenge in cancer chemotherapy. Here we investigated the mechanism of acquired resistance to a novel anticancer agent RH1 designed to be activated in cancer cells by the NQO1 enzyme. Data show that in some cancer cells RH1 may act in an NQO1-independent way. Differential proteomic analysis of breast cancer cells with acquired resistance to RH1 revealed changes in cell energy, amino acid metabolism and G2/M cell cycle transition regulation. Analysis of phosphoproteomics and protein kinase activity by multiplexed kinase inhibitor beads showed an increase in the activity of protein kinases involved in the cell cycle and stemness regulation and downregulation of proapoptotic kinases such as JNK in RH1-resistant cells. Suppression of JNK leads to the increase of cancer cell resistance to RH1. Moreover, resistant cells have enhanced expression of stem cell factor (SCF) and stem cell markers. Inhibition of SCF receptor c-KIT resulted in the attenuation of cancer stem cell enrichment and decreased amounts of tumor-initiating cells. RH1-resistant cells also acquire resistance to conventional therapeutics while remaining susceptible to c-KIT-targeted therapy. Data show that RH1 can be useful to treat cancers in the NQO1-independent way, and targeting of the cancer stem cells might be an effective approach for combating resistance to RH1 therapy.

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Liver cancer stem cells as a hierarchical society: yes or no?

Acta Biochimica et Biophysica Sinica ◽

10.1093/abbs/gmaa050 ◽

2020 ◽

Vol 52 (7) ◽

pp. 723-735 ◽

Cited By ~ 4

Author(s):

Yuanzhuo Gu ◽

Xin Zheng ◽

Junfang Ji

Keyword(s):

Stem Cells ◽

Cancer Stem Cells ◽

Recent Decade ◽

Regulatory Pathways ◽

Molecular Features ◽

The Hierarchical Structure ◽

Multiple Cell ◽

The Common ◽

Relationship Of ◽

The Relationship

Abstract Cancer stem cells (CSCs) are cells possessing abilities of self-renewal, differentiation, and tumorigenicity in NOD/SCID mice. Based on this definition, multiple cell surface markers (such as CD24, CD133, CD90, and EpCAM) as well as chemical methods are discovered to enrich liver CSCs in the recent decade. Accumulated studies have revealed molecular signatures and signaling pathways involved in regulating different liver CSCs. Among liver CSCs positive for different markers, some molecular features and regulatory pathways are commonly shared, while some are only unique in certain CSC populations. These studies imply that liver CSCs exhibit diverse heterogeneity, while a functional relationship also exists. The aim of this review is to revisit the society of liver CSCs and summarize the common or unique molecular features of known liver CSCs. We hope to call for attention of researchers on the relationship of the liver CSC subgroups and to provide clues on the hierarchical structure of the liver CSC society.

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Role of Exosomal miRNAs and the Tumor Microenvironment in Drug Resistance

Cells ◽

10.3390/cells9061450 ◽

2020 ◽

Vol 9 (6) ◽

pp. 1450 ◽

Cited By ~ 3

Author(s):

Patrick Santos ◽

Fausto Almeida

Keyword(s):

Stem Cells ◽

Drug Resistance ◽

Tumor Microenvironment ◽

Cancer Stem Cells ◽

Cancer Cells ◽

Extracellular Vesicles ◽

Therapy Resistance ◽

Chemotherapeutic Agents ◽

Exosomal Mirnas ◽

Key Factor

Tumor microenvironment (TME) is composed of different cellular populations, such as stromal, immune, endothelial, and cancer stem cells. TME represents a key factor for tumor heterogeneity maintenance, tumor progression, and drug resistance. The transport of molecules via extracellular vesicles emerged as a key messenger in intercellular communication in the TME. Exosomes are small double-layered lipid extracellular vesicles that can carry a variety of molecules, including proteins, lipids, and nucleic acids. Exosomal miRNA released by cancer cells can mediate phenotypical changes in the cells of TME to promote tumor growth and therapy resistance, for example, fibroblast- and macrophages-induced differentiation. Cancer stem cells can transfer and enhance drug resistance in neighboring sensitive cancer cells by releasing exosomal miRNAs that target antiapoptotic and immune-suppressive pathways. Exosomes induce drug resistance by carrying ABC transporters, which export chemotherapeutic agents out of the recipient cells, thereby reducing the drug concentration to suboptimal levels. Exosome biogenesis inhibitors represent a promising adjunct therapeutic approach in cancer therapy to avoid the acquisition of a resistant phenotype. In conclusion, exosomal miRNAs play a crucial role in the TME to confer drug resistance and survivability to tumor cells, and we also highlight the need for further investigations in this promising field.

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