Targeting Signaling Pathways in Cancer Stem Cells for Cancer Treatment

Targeted immunotherapy to cancer stem cells: A novel strategy of anticancer immunotherapy

Cancer is a major disease that endangers human health. Cancer drug resistance and relapse are the two main causes contributing to cancer treatment failure. Cancer stem cells (CSCs) are a small fraction of tumor cells that are responsible for tumorigenesis, metastasis, relapse, and resistance to conventional anticancer therapies. Therefore, CSCs are considered to be the root of cancer recurrence, metastasis, and drug resistance. Novel anticancer strategies need to face this new challenge and explore their efficacy against CSCs. Recently, immunotherapy has made rapid advances in cancer treatment, and its potential against CSCs is also an interesting area of research. Meanwhile, immunotherapy strategies are novel therapeutic modalities with promising results in targeting CSCs. In this review, we summarize the targeting of CSCs by various immunotherapy strategies such as monoclonal antibodies(mAb), tumor vaccines, immune checkpoint inhibitors, and chimeric antigen receptor-T cells(CAR-T) in pre-clinical and clinical studies. This review provides new insights into the application of these immunotherapeutic approaches to potential anti-tumor therapies in the future.

Molecular Changes in Breast Cancer Induced by Radiation Therapy

PURPOSE

Breast cancer treatments are based on prognostic clinicopathologic features that form the basis for therapeutic guidelines. Although the utilization of these guidelines has decreased breast cancer-associated mortality rates over the past three decades, they are not adequate for individualized therapy. Radiation therapy (RT) is the backbone of breast cancer treatment. Although a highly successful therapeutic modality clinically, from a biological perspective, preclinical studies have shown RT to have the potential to alter tumor cell phenotype, immunogenicity, and the surrounding microenvironment, potentially changing the behavior of cancer cells and resulting in a significant variation in RT response. This review presents the recent advances in revealing the complex molecular changes induced by RT in the treatment of breast cancer and highlights the complexities of translating this information into clinically relevant tools for improved prognostic insights and the revelation of novel approaches for optimizing RT.

METHODS AND MATERIALS

Current literature was reviewed with a focus on recent advances made in the elucidation of tumor-associated radiation-induced molecular changes across molecular, genetic, and proteomic bases. This review was structured with the aim of providing an up-to-date overview over the very broad and complex subject matter of radiation-induced molecular changes and radioresistance, familiarizing the reader with the broader issue at hand.

RESULTS

The subject of radiation-induced molecular changes in breast cancer has been broached from various physiological focal points including that of the immune system, immunogenicity and the abscopal effect, tumor hypoxia, breast cancer classification and subtyping, molecular heterogeneity, and molecular plasticity. It is becoming increasingly apparent that breast cancer clinical subtyping alone does not adequately account for variation in RT response or radioresistance. Multiple components of the tumor microenvironment and immune system, delivered RT dose and fractionation schedules, radiation-induced bystander effects, and intrinsic tumor physiology and heterogeneity all contribute to the resultant RT outcome.

CONCLUSIONS

Despite recent advances and improvements in anticancer therapies, tumor resistance remains a significant challenge. As new analytical techniques and technologies continue to provide crucial insight into the complex molecular mechanisms of breast cancer and its treatment responses, it is becoming more evident that personalized anticancer treatment regimens may be vital in overcoming radioresistance.

Targeting signaling pathways in cancer stem cells: A potential approach for developing novel anti-cancer therapeutics

Cancer stem cells (CSCs) have emerged as prime players in the intricate landscape of cancer development, progression, and resistance to traditional treatments. These unique cellular subpopulations own the remarkable capability of self-renewal and differentiation, giving rise to the diverse cellular makeup of tumors and fostering their recurrence following conventional therapies. In the quest for developing more effective cancer therapeutics, the focus has now shifted toward targeting the signaling pathways that govern CSCs behavior. This chapter underscores the significance of these signaling pathways in CSC biology and their potential as pivotal targets for the development of novel chemotherapy approaches. We delve into several key signaling pathways essential for maintaining the defining characteristics of CSCs, including the Wnt, Hedgehog, Notch, JAK-STAT, NF-κB pathways, among others, shedding light on their potential crosstalk. Furthermore, we highlight the latest advancements in CSC-targeted therapies, spanning from promising preclinical models to ongoing clinical trials. A comprehensive understanding of the intricate molecular aspects of CSC signaling pathways and their manipulation holds the prospective to revolutionize cancer treatment paradigms. This, in turn, could lead to more efficacious and personalized therapies with the ultimate goal of eradicating CSCs and enhancing overall patient outcomes. The exploration of CSC signaling pathways represents a key step towards a brighter future in the battle against cancer.

Natural products derived from medicinal plants and microbes might act as a game-changer in breast cancer: a comprehensive review of preclinical and clinical studies

Breast cancer (BC) is the most prevalent neoplasm among women. Genetic and environmental factors lead to BC development and on this basis, several preventive - screening and therapeutic interventions have been developed. Hormones, both in the form of endogenous hormonal signaling or hormonal contraceptives, play an important role in BC pathogenesis and progression. On top of these, breast microbiota includes both species with an immunomodulatory activity enhancing the host's response against cancer cells and species producing proinflammatory cytokines associated with BC development. Identification of novel multitargeted therapeutic agents with poly-pharmacological potential is a dire need to combat advanced and metastatic BC. A growing body of research has emphasized the potential of natural compounds derived from medicinal plants and microbial species as complementary BC treatment regimens, including dietary supplements and probiotics. In particular, extracts from plants such as Artemisia monosperma Delile, Origanum dayi Post, Urtica membranacea Poir. ex Savigny, Krameria lappacea (Dombey) Burdet & B.B. Simpson and metabolites extracted from microbes such as Deinococcus radiodurans and Streptomycetes strains as well as probiotics like Bacillus coagulans and Lactobacillus brevis MK05 have exhibited antitumor effects in the form of antiproliferative and cytotoxic activity, increase in tumors' chemosensitivity, antioxidant activity and modulation of BC - associated molecular pathways. Further, bioactive compounds like 3,3'-diindolylmethane, epigallocatechin gallate, genistein, rutin, resveratrol, lycopene, sulforaphane, silibinin, rosmarinic acid, and shikonin are of special interest for the researchers and clinicians because these natural agents have multimodal action and act via multiple ways in managing the BC and most of these agents are regularly available in our food and fruit diets. Evidence from clinical trials suggests that such products had major potential in enhancing the effectiveness of conventional antitumor agents and decreasing their side effects. We here provide a comprehensive review of the therapeutic effects and mechanistic underpinnings of medicinal plants and microbial metabolites in BC management. The future perspectives on the translation of these findings to the personalized treatment of BC are provided and discussed.

Spatial Transcriptomics Identifies Expression Signatures Specific to Lacrimal Gland Adenoid Cystic Carcinoma Cells

Although primary tumors of the lacrimal gland are rare, adenoid cystic carcinoma (ACC) is the most common and lethal epithelial lacrimal gland malignancy. Traditional management of lacrimal gland adenoid cystic carcinoma (LGACC) involves the removal of the eye and surrounding socket contents, followed by chemoradiation. Even with this radical treatment, the 10-year survival rate for LGACC is 20% given the propensity for recurrence and metastasis. Due to the rarity of LGACC, its pathobiology is not well-understood, leading to difficulties in diagnosis, treatment, and effective management. Here, we integrate bulk RNA sequencing (RNA-seq) and spatial transcriptomics to identify a specific LGACC gene signature that can inform novel targeted therapies. Of the 3499 differentially expressed genes identified by bulk RNA-seq, the results of our spatial transcriptomic analysis reveal 15 upregulated and 12 downregulated genes that specifically arise from LGACC cells, whereas fibroblasts, reactive fibrotic tissue, and nervous and skeletal muscle account for the remaining bulk RNA-seq signature. In light of the analysis, we identified a transitional state cell or stem cell cluster. The results of the pathway analysis identified the upregulation of PI3K-Akt signaling, IL-17 signaling, and multiple other cancer pathways. This study provides insights into the molecular and cellular landscape of LGACC, which can inform new, targeted therapies to improve patient outcomes.

Profiling and targeting cancer stem cell signaling pathways for cancer therapeutics

Tumorigenic cancer stem cells (CSCs) represent a subpopulation of cells within the tumor that express genetic and phenotypic profiles and signaling pathways distinct from the other tumor cells. CSCs have eluded many conventional anti-oncogenic treatments, resulting in metastases and relapses of cancers. Effectively targeting CSCs' unique self-renewal and differentiation properties would be a breakthrough in cancer therapy. A better characterization of the CSCs' unique signaling mechanisms will improve our understanding of the pathology and treatment of cancer. In this paper, we will discuss CSC origin, followed by an in-depth review of CSC-associated signaling pathways. Particular emphasis is given on CSC signaling pathways' ligand-receptor engagement, upstream and downstream mechanisms, and associated genes, and molecules. Signaling pathways associated with regulation of CSC development stand as potential targets of CSC therapy, which include Wnt, TGFβ (transforming growth factor-β)/SMAD, Notch, JAK-STAT (Janus kinase-signal transducers and activators of transcription), Hedgehog (Hh), and vascular endothelial growth factor (VEGF). Lastly, we will also discuss milestone discoveries in CSC-based therapies, including pre-clinical and clinical studies featuring novel CSC signaling pathway cancer therapeutics. This review aims at generating innovative views on CSCs toward a better understanding of cancer pathology and treatment.

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.

Spice-Derived Bioactive Compounds Confer Colorectal Cancer Prevention via Modulation of Gut Microbiota

Colorectal cancer (CRC) is the second most frequent cause of cancer-related mortality among all types of malignancies. Sedentary lifestyles, obesity, smoking, red and processed meat, low-fiber diets, inflammatory bowel disease, and gut dysbiosis are the most important risk factors associated with CRC pathogenesis. Alterations in gut microbiota are positively correlated with colorectal carcinogenesis, as these can dysregulate the immune response, alter the gut's metabolic profile, modify the molecular processes in colonocytes, and initiate mutagenesis. Changes in the daily diet, and the addition of plant-based nutraceuticals, have the ability to modulate the composition and functionality of the gut microbiota, maintaining gut homeostasis and regulating host immune and inflammatory responses. Spices are one of the fundamental components of the human diet that are used for their bioactive properties (i.e., antimicrobial, antioxidant, and anti-inflammatory effects) and these exert beneficial effects on health, improving digestion and showing anti-inflammatory, immunomodulatory, and glucose- and cholesterol-lowering activities, as well as possessing properties that affect cognition and mood. The anti-inflammatory and immunomodulatory properties of spices could be useful in the prevention of various types of cancers that affect the digestive system. This review is designed to summarize the reciprocal interactions between dietary spices and the gut microbiota, and highlight the impact of dietary spices and their bioactive compounds on colorectal carcinogenesis by targeting the gut microbiota.

The Molecular and Cellular Strategies of Glioblastoma and Non-Small-Cell Lung Cancer Cells Conferring Radioresistance

Ionizing radiation (IR) has been shown to play a crucial role in the treatment of glioblastoma (GBM; grade IV) and non-small-cell lung cancer (NSCLC). Nevertheless, recent studies have indicated that radiotherapy can offer only palliation owing to the radioresistance of GBM and NSCLC. Therefore, delineating the major radioresistance mechanisms may provide novel therapeutic approaches to sensitize these diseases to IR and improve patient outcomes. This review provides insights into the molecular and cellular mechanisms underlying GBM and NSCLC radioresistance, where it sheds light on the role played by cancer stem cells (CSCs), as well as discusses comprehensively how the cellular dormancy/non-proliferating state and polyploidy impact on their survival and relapse post-IR exposure.

Signaling pathways in the regulation of cancer stem cells and associated targeted therapy

Cancer stem cells (CSCs) are defined as a subpopulation of malignant tumor cells with selective capacities for tumor initiation, self-renewal, metastasis, and unlimited growth into bulks, which are believed as a major cause of progressive tumor phenotypes, including recurrence, metastasis, and treatment failure. A number of signaling pathways are involved in the maintenance of stem cell properties and survival of CSCs, including well-established intrinsic pathways, such as the Notch, Wnt, and Hedgehog signaling, and extrinsic pathways, such as the vascular microenvironment and tumor-associated immune cells. There is also intricate crosstalk between these signal cascades and other oncogenic pathways. Thus, targeting pathway molecules that regulate CSCs provides a new option for the treatment of therapy-resistant or -refractory tumors. These treatments include small molecule inhibitors, monoclonal antibodies that target key signaling in CSCs, as well as CSC-directed immunotherapies that harness the immune systems to target CSCs. This review aims to provide an overview of the regulating networks and their immune interactions involved in CSC development. We also address the update on the development of CSC-directed therapeutics, with a special focus on those with application approval or under clinical evaluation.

Critical Role of Aquaporins in Cancer: Focus on Hematological Malignancies

Simple Summary

Aquaporins are proteins able to regulate the transfer of water and other small substances such as ions, glycerol, urea, and hydrogen peroxide across cellular membranes. AQPs provide for a huge variety of physiological phenomena; their alteration provokes several types of pathologies including cancer and hematological malignancies. Our review presents data revealing the possibility of employing aquaporins as biomarkers in patients with hematological malignancies and evaluates the possibility that interfering with the expression of aquaporins could represent an effective treatment for hematological malignancies.

Abstract

Aquaporins are transmembrane molecules regulating the transfer of water and other compounds such as ions, glycerol, urea, and hydrogen peroxide. Their alteration has been reported in several conditions such as cancer. Tumor progression might be enhanced by aquaporins in modifying tumor angiogenesis, cell volume adaptation, proteases activity, cell–matrix adhesions, actin cytoskeleton, epithelial–mesenchymal transitions, and acting on several signaling pathways facilitating cancer progression. Close connections have also been identified between the aquaporins and hematological malignancies. However, it is difficult to identify a unique action exerted by aquaporins in different hemopathies, and each aquaporin has specific effects that vary according to the class of aquaporin examined and to the different neoplastic cells. However, the expression of aquaporins is altered in cell cultures and in patients with acute and chronic myeloid leukemia, in lymphoproliferative diseases and in multiple myeloma, and the different expression of aquaporins seems to be able to influence the efficacy of treatment and could have a prognostic significance, as greater expression of aquaporins is correlated to improved overall survival in leukemia patients. Finally, we assessed the possibility that modifying the aquaporin expression using aquaporin-targeting regulators, specific monoclonal antibodies, and even aquaporin gene transfer could represent an effective therapy of hematological malignancies.

Stem Cell Models for Breast and Colon Cancer: Experimental Approach for Drug Discovery

The progression of the early stages of female breast and colon cancer to metastatic disease represents a major cause of mortality in women. Multi-drug chemotherapy and/or pathway selective targeted therapy are notable for their off-target effects and are associated with spontaneous and/or acquired chemotherapy resistance and the emergence of premalignant chemo-resistant cancer-initiating stem cells. The stem cell populations are responsible for the evolution of therapy-resistant metastatic disease. These limitations emphasize an unmet need to develop reliable drug-resistant cancer stem cell models as novel experimental approaches for therapeutic alternatives in drug discovery platforms. Drug-resistant stem cell models for breast and colon cancer subtypes exhibit progressive growth in the presence of cytotoxic chemo-endocrine therapeutics. The resistant cells exhibit upregulated expressions of stem cell-selective cellular and molecular markers. Dietary phytochemicals, nutritional herbs and their constituent bioactive compounds have documented growth inhibitory efficacy for cancer stem cells. The mechanistic leads for the stem cell-targeted efficacy of naturally occurring agents validates the present experimental approaches for new drug discovery as therapeutic alternatives for therapy-resistant breast and colon cancer. The present review provides a systematic discussion of published evidence on (i) conventional/targeted therapy for breast and colon cancer, (ii) cellular and molecular characterization of stem cell models and (iii) validation of the stem cell models as an experimental approach for novel drug discovery of therapeutic alternatives for therapy-resistant cancers.

Hedgehog/GLI signaling in hematopoietic development and acute myeloid leukemia—From bench to bedside

While the underlying genetic alterations and biology of acute myeloid leukemia (AML), an aggressive hematologic malignancy characterized by clonal expansion of undifferentiated myeloid cells, have been gradually unraveled in the last decades, translation into clinical treatment approaches has only just begun. High relapse rates remain a major challenge in AML therapy and are to a large extent attributed to the persistence of treatment-resistant leukemic stem cells (LSCs). The Hedgehog (HH) signaling pathway is crucial for the development and progression of multiple cancer stem cell driven tumors, including AML, and has therefore gained interest as a therapeutic target. In this review, we give an overview of the major components of the HH signaling pathway, dissect HH functions in normal and malignant hematopoiesis, and specifically elaborate on the role of HH signaling in AML pathogenesis and resistance. Furthermore, we summarize preclinical and clinical HH inhibitor studies, leading to the approval of the HH pathway inhibitor glasdegib, in combination with low-dose cytarabine, for AML treatment.

Cancer stem cells and tumor heterogeneity: Deciphering the role in tumor progression and metastasis

Tumor heterogeneity, in principle, reflects the variation among different cancer cell populations. It can be termed inter- or intra-tumoral heterogeneity, respectively, based on its occurrence in various tissues from diverse patients or within a single tumor. The intra-tumoral heterogeneity is one of the leading causes of cancer progression and treatment failure, with the cancer stem cells (CSCs) contributing immensely to the same. These niche cells, similar to normal stem cells, possess the characteristics of self-renewal and differentiation into multiple cell types. Moreover, CSCs contribute to tumor growth and surveillance by promoting recurrence, metastasis, and therapeutic resistance. Diverse factors, including intracellular signalling pathways and tumor microenvironment (TME), play a vital role in regulating these CSCs. Although a panel of markers is considered to identify the CSC pool in various cancers, further research is needed to discriminate cancer-specific CSC markers in those. CSCs have also been found to be promising therapeutic targets for cancer therapy. Several small molecules, natural compounds, antibodies, chimeric antigen receptor T (CAR-T) cells, and CAR-natural killer (CAR-NK) cells have emerged as therapeutic tools for specific targeting of CSCs. Interestingly, many of these are in clinical trials too. Despite being a much-explored avenue of research for years, and we have come to understand its nitty-gritty, there is still a tremendous gap in our knowledge concerning its precise genesis and regulation. Hence, a concrete understanding is needed to assess the CSC-TME link and how to target different cancer-specific CSCs by designing newer tools. In this review, we have summarized CSC, its causative, different pathways and factors regulating its growth, association with tumor heterogeneity, and last but not least, discussed many of the promising CSC-targeted therapies for combating cancer metastasis.

Drug-Resistant Stem Cells: Novel Approach for Colon Cancer Therapy

Metastatic progression of female breast and colon cancer represents a major cause of mortality in women. Spontaneous/acquired resistance to conventional and targeted chemo-endocrine therapy is associated with the emergence of drug-resistant tumor-initiating cancer stem cell populations. The cancer-initiating premalignant stem cells exhibit activation of select cancer cell signaling pathways and undergo epithelial–mesenchymal transition, leading to the evolution of a metastatic phenotype. The development of reliable cancer stem cell models provides valuable experimental approaches to identify novel testable therapeutic alternatives for therapy-resistant cancer. Drug-resistant stem cell models for molecular subtypes of clinical breast cancer and for genetically predisposed colon cancer are developed by selecting epithelial cells that survive in the presence of cytostatic concentrations of relevant therapeutic agents. These putative stem cells are characterized by the expression status of select cellular and molecular stem cell markers. The stem cell models are utilized as experimental approaches to examine the stem-cell-targeted growth inhibitory efficacy of naturally occurring dietary phytochemicals. The present review provides a systematic discussion on (i) conceptual and experimental aspects relevant to the chemo-endocrine therapy of breast and colon cancer, (ii) molecular/cellular aspects of cancer stem cells and (iii) potential stem-cell-targeting lead compounds as testable alternatives against the progression of therapy-resistant breast and colon cancer.

Anti-tumor effects of cryptotanshinone (C19H20O3) in human osteosarcoma cell lines

Osteosarcoma is the most prevalent malignant bone tumor and occurs most commonly in the adolescent and young adult population. Despite the recent advances in surgeries and chemotherapy, the overall survival in patients with resectable metastases is around 20%. This challenge in osteosarcoma is often attributed to the drastic differences in the tumorigenic profiles and mutations among patients. With diverse mutations and multiple oncogenes, it is necessary to identify the therapies that can attack various mutations and simultaneously have minor side-effects. In this paper, we constructed the osteosarcoma pathway from literature and modeled it using ordinary differential equations. We then simulated this network for every possible gene mutation and their combinations and ranked different drug combinations based on their efficacy to drive a mutated osteosarcoma network towards cell death. Our theoretical results predict that drug combinations with Cryptotanshinone (C₁₉H₂₀O₃), a traditional Chinese herb derivative, have the best overall performance. Specifically, Cryptotanshinone in combination with Temsirolimus inhibit the JAK/STAT, MAPK/ERK, and PI3K/Akt/mTOR pathways and induce cell death in tumor cells. We corroborated our theoretical predictions using wet-lab experiments on SaOS2, 143B, G292, and HU03N1 human osteosarcoma cell lines, thereby demonstrating the potency of Cryptotanshinone in fighting osteosarcoma.

Gene Mutations Associated With Clinical Characteristics in the Tumors of Patients With Breast Cancer

Background

Clinical characteristics including estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2) are important biomarkers in the treatment of breast cancer, but how genomic mutations affect their status is rarely studied. This study aimed at finding genomic mutations associated with these clinical characteristics.

Methods

There were 160 patients with breast cancer enrolled in this study. Samples from those patients were used for next-generation sequencing, targeting a panel of 624 pan-cancer genes. Short nucleotide mutations, copy number variations, and gene fusions were identified for each sample. Fisher’s exact test compared each pair of genes. A similarity score was constructed with the resulting P-values. Genes were clustered with the similarity scores. The identified gene clusters were compared to the status of clinical characteristics including ER, PR, HER2, and a family history of cancer (FH) in terms of the mutations in patients.

Results

Gene-by-gene analysis found that CCND1 mutations were positively correlated with ER status while ERBB2 and CDK12 mutations were positively correlated with HER2 status. Mutation-based clustering identified four gene clusters. Gene cluster 1 (ADGRA2, ZNF703, FGFR1, KAT6A, and POLB) was significantly associated with PR status; gene cluster 2 (COL1A1, AXIN2, ZNF217, GNAS, and BRIP1) and gene cluster 3 (FGF3, FGF4, FGF19, and CCND1) were significantly associated with ER status; gene cluster 2 was also negatively associated with a family history of cancer; and gene cluster 4 was significantly negatively associated with age. Patients were classified into four corresponding groups. Patient groups 1, 2, 3, and 4 had 24.1%, 36.5%, 38.7%, and 41.3% of patients with an FDA-recognized biomarker predictive of response to an FDA-approved drug, respectively.

Conclusion

This study identified genomic mutations positively associated with ER and PR status. These findings not only revealed candidate genes in ER and PR status maintenance but also provided potential treatment targets for patients with endocrine therapy resistance.

Molecular Mechanisms Involving the Sonic Hedgehog Pathway in Lung Cancer Therapy: Recent Advances

According to the latest statistics from the International Agency for Research on Cancer (IARC), lung cancer is one of the most lethal malignancies in the world, accounting for approximately 18% of all cancer-associated deaths. Yet, even with aggressive interventions for advanced lung cancer, the five-year survival rate remains low, at around 15%. The hedgehog signaling pathway is highly conserved during embryonic development and is involved in tissue homeostasis as well as organ development. However, studies have documented an increasing prevalence of aberrant activation of HH signaling in lung cancer patients, promoting malignant lung cancer progression with poor prognostic outcomes. Inhibitors targeting the HH pathway have been widely used in tumor therapy, however, they still cannot avoid the occurrence of drug resistance. Interestingly, natural products, either alone or in combination with chemotherapy, have greatly improved overall survival outcomes for lung cancer patients by acting on the HH signaling pathway because of its unique and excellent pharmacological properties. In this review, we elucidate on the underlying molecular mechanisms through which the HH pathway promotes malignant biological behaviors in lung cancer, as well as the potential of inhibitors or natural compounds in targeting HH signaling for clinical applications in lung cancer therapy.

Metastasis and MAPK Pathways

Cancer is a leading cause of death worldwide. In many cases, the treatment of the disease is limited due to the metastasis of cells to distant locations of the body through the blood and lymphatic drainage. Most of the anticancer therapeutic options focus mainly on the inhibition of tumor cell growth or the induction of cell death, and do not consider the molecular basis of metastasis. The aim of this work is to provide a comprehensive review focusing on cancer metastasis and the mitogen-activated protein kinase (MAPK) pathway (ERK/JNK/P38 signaling) as a crucial modulator of this process.

Effect of aberrant DNA methylation on cancer stem cell properties

DNA methylation, as an epigenetic mechanism, occurs by adding a methyl group of cytosines in position 5 by DNA methyltransferases and has essential roles in cellular function, especially in the transcriptional regulation of embryonic and adult stem cells. Hypomethylation and hypermethylation cause either the expression or inhibition of genes, and there is a tight balance between regulating the activation or repression of genes in normal cellular activity. Abnormal methylation is well-known hallmark of cancer development and progression and can switch normal stem cells into cancer stem cells. Cancer Stem Cells (CSCs) are minor populations of tumor cells that exhibit unique properties such as self-regeneration, resistance to chemotherapy, and high ability of metastasis. The purpose of this paper is to show how aberrant DNA methylation accumulation affects self-renewal, differentiation, multidrug-resistant, and metastasis processes in cancer stem cells.

Molecular Docking as a Therapeutic Approach for Targeting Cancer Stem Cell Metabolic Processes

Cancer stem cells (CSCs) are subpopulation of cells which have been demonstrated in a variety of cancer models and involved in cancer initiation, progression, and development. Indeed, CSCs which seem to form a small percentage of tumor cells, display resembling characteristics to natural stem cells such as self-renewal, survival, differentiation, proliferation, and quiescence. Moreover, they have some characteristics that eventually can demonstrate the heterogeneity of cancer cells and tumor progression. On the other hand, another aspect of CSCs that has been recognized as a central concern facing cancer patients is resistance to mainstays of cancer treatment such as chemotherapy and radiation. Owing to these details and the stated stemness capabilities, these immature progenitors of cancerous cells can constantly persist after different therapies and cause tumor regrowth or metastasis. Further, in both normal development and malignancy, cellular metabolism and stemness are intricately linked and CSCs dominant metabolic phenotype changes across tumor entities, patients, and tumor subclones. Hence, CSCs can be determined as one of the factors that correlate to the failure of common therapeutic approaches in cancer treatment. In this context, researchers are searching out new alternative or complementary therapies such as targeted methods to fight against cancer. Molecular docking is one of the computational modeling methods that has a new promise in cancer cell targeting through drug designing and discovering programs. In a simple definition, molecular docking methods are used to determine the metabolic interaction between two molecules and find the best orientation of a ligand to its molecular target with minimal free energy in the formation of a stable complex. As a comprehensive approach, this computational drug design method can be thought more cost-effective and time-saving compare to other conventional methods in cancer treatment. In addition, increasing productivity and quality in pharmaceutical research can be another advantage of this molecular modeling method. Therefore, in recent years, it can be concluded that molecular docking can be considered as one of the novel strategies at the forefront of the cancer battle via targeting cancer stem cell metabolic processes.

Intrinsic and Extrinsic Factors Impacting Cancer Stemness and Tumor Progression

Tumor heterogeneity represents an important limitation to the development of effective cancer therapies. The presence of cancer stem cells (CSCs) and their differentiation hierarchies contribute to cancer complexity and confer tumors the ability to grow, resist treatment, survive unfavorable conditions, and invade neighboring and distant tissues. A large body of research is currently focusing on understanding the properties of CSCs, including their cellular and molecular origin, as well as their biological behavior in different tumor types. In turn, this knowledge informs strategies for targeting these tumor initiating cells and related cancer stemness. Cancer stemness is modulated by the tumor microenvironment, which influences CSC function and survival. Several advanced in vitro models are currently being developed to study cancer stemness in order to advance new knowledge of the key molecular pathways involved in CSC self-renewal and dormancy, as well as to mimic the complexity of patients' tumors in pre-clinical drug testing. In this review, we discuss CSCs and the modulation of cancer stemness by the tumor microenvironment, stemness factors and signaling pathways. In addition, we introduce current models that allow the study of CSCs for the development of new targeted therapies.

Ellagitannins, promising pharmacological agents for the treatment of cancer stem cells

Human tumors comprise subpopulations of cells called cancer stem cells (CSCs) that possess stemness properties. CSCs can initiate tumors and cause recurrence, metastasis and are also responsible for chemo- and radio-resistance. CSCs may use signaling pathways similar to normal stem cells, including Notch, JAK/STAT, Wnt and Hedgehog pathways. Ellagitannins (ETs) are a broad group of substances with chemopreventive and anticancer activities. The antitumor activity of ETs and their derivatives are mainly related to their antiinflammatory capacity. They are therefore able to modulate secretory growth factors and pro-inflammatory mediators such as IL-6, TGF-β, TNF-α, IL-1β and IFN-γ. Evidence suggests that ETs display their anticancer effect by targeting CSCs and disrupting stem cell signaling. However, there are still few studies in this field. Therefore, high-quality studies are needed to firmly establish the clinical efficacy of the ETs on CSCs. This paper reviews the structures, sources and pharmacokinetics of ETs. It also focuses on the function of ETs and their effects on CSCs-related cytokines and the relationship between ETs and signaling pathways in CSCs.

The Wnt/β-catenin signaling pathway in the tumor microenvironment of hepatocellular carcinoma

The Wnt/β-catenin signaling pathway regulates many aspects of tumor biology, and many studies have focused on the role of this signaling pathway in tumor cells. However, it is now clear that tumor development and metastasis depend on the two-way interaction between cancer cells and their environment, thereby forming a tumor microenvironment (TME). In this review, we discuss how Wnt/β-catenin signaling regulates cross-interactions among different components of the TME, including immune cells, stem cells, tumor vasculature, and noncellular components of the TME in hepatocellular carcinoma. We also investigate their preclinical and clinical insights for primary liver cancer intervention, and explore the significance of using Wnt/β-catenin mutations as a biomarker to predict resistance in immunotherapy.

The high expression of miR-31 in lung adenocarcinoma inhibits the malignancy of lung adenocarcinoma tumor stem cells

Therapies for lung adenocarcinoma (LUAD) are mainly limited by drug resistance, metastasis or recurrence related to cancer stem cells (CSCs) with high proliferation and self-renewing. This research validated that miR-31 was over-expressed in LUAD by the analysis of generous clinical samples data. And the results of clinical data analysis showed that high expression of miR-31 was more common in patients with worse prognosis. The genes differentially expressed in LUAD tissues compared with normal tissues and A549CD133⁺ cells (LUAD CSCs) compared with A549 cells were separately screened from Gene Expression Profiling Interactive Analysis and GEO datasets. The target genes that may play a role in the regulation of lung adenocarcinoma was screened by comparison between the differential genes and the target genes of miR-31. The functional enrichment analysis of GO Biological Processes showed that the expression of target genes related to cell proliferation was increased, while the expression of target genes related to cell invasion and metastasis was decreased in LUAD tissues and A549CD133⁺ cells. The results suggested that miR-31 may have a significant inhibitory effect on the differentiation, invasion, metastasis and adhesion of LUAD CSCs, which was verified in vivo and in vitro experiments. Knock down of miR-31 accelerated xenograft tumor growth and liver metastasis in vivo. Likewise, the carcinogenicity, invasion and metastasis of A549CD133⁺ CSCs were promoted after miR-31 knockdown. The study validated that miR-31 was up regulated in LUAD and its expression may affect the survival time of patients with lung adenocarcinoma, which indicated that miR-31 may have potential value for diagnosis and prognosis of LUAD. However, the inhibitory effect of miR-31 on tumorigenesis, invasion and metastasis of lung adenocarcinoma CSCs suggested its complexity in the regulation of lung adenocarcinoma, which may be related to its extensive regulation of various target genes.

The plasticity of pancreatic cancer stem cells: implications in therapeutic resistance

The ever-growing perception of cancer stem cells (CSCs) as a plastic state rather than a hardwired defined entity has evolved our understanding of the functional and biological plasticity of these elusive components in malignancies. Pancreatic cancer (PC), based on its biological features and clinical evolution, is a prototypical example of a CSC-driven disease. Since the discovery of pancreatic CSCs (PCSCs) in 2007, evidence has unraveled their control over many facets of the natural history of PC, including primary tumor growth, metastatic progression, disease recurrence, and acquired drug resistance. Consequently, the current near-ubiquitous treatment regimens for PC using aggressive cytotoxic agents, aimed at ‘‘tumor debulking’’ rather than eradication of CSCs, have proven ineffective in providing clinically convincing improvements in patients with this dreadful disease. Herein, we review the key hallmarks as well as the intrinsic and extrinsic resistance mechanisms of CSCs that mediate treatment failure in PC and enlist the potential CSC-targeting ‘natural agents’ that are gaining popularity in recent years. A better understanding of the molecular and functional landscape of PCSC-intrinsic evasion of chemotherapeutic drugs offers a facile opportunity for treating PC, an intractable cancer with a grim prognosis and in dire need of effective therapeutic advances.

Wnt/β-Catenin Inhibition Disrupts Carboplatin Resistance in Isogenic Models of Triple-Negative Breast Cancer

Triple-Negative Breast Cancer (TNBC) is the most aggressive breast cancer subtype, characterized by limited treatment options and higher relapse rates than hormone-receptor-positive breast cancers. Chemotherapy remains the mainstay treatment for TNBC, and platinum salts have been explored as a therapeutic alternative in neo-adjuvant and metastatic settings. However, primary and acquired resistance to chemotherapy in general and platinum-based regimens specifically strongly hampers TNBC management. In this study, we used carboplatin-resistant in vivo patient-derived xenograft and isogenic TNBC cell-line models and detected enhanced Wnt/β-catenin activity correlating with an induced expression of stem cell markers in both resistant models. In accordance, the activation of canonical Wnt signaling in parental TNBC cell lines increases stem cell markers' expression, formation of tumorspheres and promotes carboplatin resistance. Finally, we prove that Wnt signaling inhibition resensitizes resistant models to carboplatin both in vitro and in vivo, suggesting the synergistic use of Wnt inhibitors and carboplatin as a therapeutic option in TNBC. Here we provide evidence for a prominent role of Wnt signaling in mediating resistance to carboplatin, and we establish that combinatorial targeting of Wnt signaling overcomes carboplatin resistance enhancing chemotherapeutic drug efficacy.

The many facets of Notch signaling in breast cancer: toward overcoming therapeutic resistance

In this review, Nandi et al. revisit the mechanisms by which Notch receptors and ligands contribute to normal mammary gland development and breast tumor progression. The authors also discuss combinatorial approaches aimed at disrupting Notch- and TME-mediated resistance that may improve prognosis in breast cancer patients.

Breast cancer is the second leading cause of cancer-related death in women and is a complex disease with high intratumoral and intertumoral heterogeneity. Such heterogeneity is a major driving force behind failure of current therapies and development of resistance. Due to the limitations of conventional therapies and inevitable emergence of acquired drug resistance (chemo and endocrine) as well as radio resistance, it is essential to design novel therapeutic strategies to improve the prognosis for breast cancer patients. Deregulated Notch signaling within the breast tumor and its tumor microenvironment (TME) is linked to poor clinical outcomes in treatment of resistant breast cancer. Notch receptors and ligands are also important for normal mammary development, suggesting the potential for conserved signaling pathways between normal mammary gland development and breast cancer. In this review, we focus on mechanisms by which Notch receptors and ligands contribute to normal mammary gland development and breast tumor progression. We also discuss how complex interactions between cancer cells and the TME may reduce treatment efficacy and ultimately lead to acquired drug or radio resistance. Potential combinatorial approaches aimed at disrupting Notch- and TME-mediated resistance that may aid in achieving in an improved patient prognosis are also highlighted.

RAD51AP1 Loss Attenuates Colorectal Cancer Stem Cell Renewal and Sensitizes to Chemotherapy

DNA damage, induced by either chemical carcinogens or environmental pollutants, plays an important role in the initiation of colorectal cancer. DNA repair processes, however, are involved in both protecting against cancer formation, and also contributing to cancer development, by ensuring genomic integrity and promoting the efficient DNA repair in tumor cells, respectively. Although DNA repair pathways have been well exploited in the treatment of breast and ovarian cancers, the role of DNA repair processes and their therapeutic efficacy in colorectal cancer is yet to be appreciably explored. To understand the role of DNA repair, especially homologous recombination (HR), in chemical carcinogen-induced colorectal cancer growth, we unraveled the role of RAD51AP1 (RAD51-associated protein 1), a protein involved in HR, in genotoxic carcinogen (azoxymethane, AOM)-induced colorectal cancer. Although AOM treatment alone significantly increased RAD51AP1 expression, the combination of AOM and dextran sulfate sodium (DSS) treatment dramatically increased by several folds. RAD51AP1 expression is found in mouse colonic crypt and proliferating cells. RAD51AP1 expression is significantly increased in majority of human colorectal cancer tissues, including BRAF/KRAS mutant colorectal cancer, and associated with reduced treatment response and poor prognosis. Rad51ap1-deficient mice were protected against AOM/DSS-induced colorectal cancer. These observations were recapitulated in a genetically engineered mouse model of colorectal cancer (Apc^{Min /+} ). Furthermore, chemotherapy-resistant colorectal cancer is associated with increased RAD51AP1 expression. This phenomenon is associated with reduced cell proliferation and colorectal cancer stem cell (CRCSC) self-renewal. Overall, our studies provide evidence that RAD51AP1 could be a novel diagnostic marker for colorectal cancer and a potential therapeutic target for colorectal cancer prevention and treatment. IMPLICATIONS: This study provides first in vivo evidence that RAD51AP1 plays a critical role in colorectal cancer growth and drug resistance by regulating CRCSC self-renewal.

Treatment of basal cell carcinoma with vismodegib: future or present?

BACKGROUND

Since the introduction of Vismodegib as treatment of recurrent locally advanced basal cell carcinoma (laBCC), clinicians are faced with new dilemmas: 'Can Vismodegib replace complex reconstructions?', 'What is the role of neoadjuvant use of Vismodegib?' and 'What is the best approach in case of complete clinical remission after Vismodegib in a neoadjuvant setting?'

METHODS

Case report and literature review.

RESULTS

Case report Complete dermoscopic remission after eight months Vismodegib was obtained in a patient with recurrent laBCC. Follow-up was 12 months. Literature review: Vismodegib shows histologic clearance in 42% of patients with operable basal cell carcinoma. Recurrence after neoadjuvant use of Vismodegib in laBCC was described. Moreover, histology revealed residual tumour cells in cases of complete clinical remission after 6 months Vismodegib.

CONCLUSIONS

Vismodegib cannot replace complex reconstructions. However, in unresectable laBCC, Vismodegib can provide a bridge to surgery. Due to the possibility of persistent tumour cells, we recommend imaging-assisted surgery and an imaging-based follow-up. In case of complete clinical remission after Vismodegib in a neoadjuvant setting, we recommend that Vismodegib be continued as long as the adverse effects are tolerated and an imaging-based follow-up is advised.

Signaling pathways governing breast cancer stem cells behavior

Breast cancer is the second common cancer and the leading cause of malignancy among females overall. Breast cancer stem cells (BCSCs) are a small population of breast cancer cells that play a critical role in the metastasis of breast cancer to other organs in the body. BCSCs have both self-renewal and differentiation capacities, which are thought to contribute to the aggressiveness of metastatic lesions. Therefore, targeting BCSCs can be a suitable approach for the treatment and metastasis of breast cancer. Growing evidence has indicated that the Wnt, NFκB, Notch, BMP2, STAT3, and hedgehog (Hh) signaling pathways govern epithelial-to-mesenchymal transition (EMT) activation, growth, and tumorigenesis of BCSCs in the primary regions. miRNAs as the central regulatory molecules also play critical roles in BCSC self-renewal, metastasis, and drug resistance. Hence, targeting these pathways might be a novel therapeutic approach for breast cancer diagnosis and therapy. This review discusses known signaling mechanisms involved in the stimulation or prevention of BCSC self-renewal, metastasis, and tumorigenesis.

Cancer stem cells targets and combined therapies to prevent cancer recurrence

Cancer stem cells (CSCs) control the dynamics of tumorigenesis by self-renewal ability and differentiation potential. These properties contribute towards tumor malignancy, metastasis, cellular heterogeneity, and immune escape, which are regulated by multiple signaling pathways. The CSCs are chemoresistant and cause cancer recurrence, generally recognized as a small side-population that eventually leads to tumor relapse. Despite many treatment options available, none can be considered entirely efficient due to a lack of specificity and dose limitation. This review primarily highlights the processes involved in CSCs development and maintenance. Secondly, the current effective therapies based on stem cells, cell-free therapies that involve exosomes and miRNAs, and photodynamic therapy have been discussed. Also, the inhibitors that specifically target various signaling pathways, which can be used in combination to control CSCs kinetics have been highlighted. Conclusively, this comprehensive review is a detailed study of recently developed novel treatment strategies that will facilitate in coming up with better-targeted approaches against CSCs.

Profiling of microRNAs in actinic keratosis and cutaneous squamous cell carcinoma patients

Actinic keratosis (AK) is a common skin lesion often defined as premalignant with more evidence indicating it as early stage of cutaneous squamous cell carcinoma (cSCC). The AK may remain stable, transform towards incisive cSCC or in some cases revert spontaneously. Several different underlying conditions can increase risk of cSCC, however, advanced age represents major risk of AK and its progression towards cSCC indicating increased risk during chronological aging. Importantly, AK and cSCC are characterized by similar genetic profile, which lead researchers to search for novel biomarkers allowing early detection. As skin sampling is often invasive and causes scaring, in the current study, we investigated a novel approach to establish potential blood circulating genetic markers in patients diagnosed with AK and cSCC. Based on clinical diagnosis and dermoscopy, we recruited 13 patients with AK (divided into two groups: the first included patients with no more than three lesions, the second group included patients with at least ten lesions) and two additional individuals diagnosed with cSCC. Deep sequencing analysis of serum circulating miRNAs detected a total of 68 expressed miRNAs. Further analysis indicated 2 regulated miRNAs for AK cohort and 12 miRNAs for cSCC patients, while there were 26 miRNAs differentially regulated between cSCC and AK patients. There was also one commonly regulated miRNA between AK and cSCC patients and ten miRNAs that were regulated in cSCC when compared with both control and AK patients. We did not observe any differences between the AK groups. In conclusion, our analysis detected in circulation some miRNA that were previously recognized as important in AK, cSCC, and other type of skin cancer supporting this approach as potential non-invasive diagnosis of AK and cSCC.

Comprehending the crosstalk between Notch, Wnt and Hedgehog signaling pathways in oral squamous cell carcinoma - clinical implications

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a malignant oral cavity neoplasm that affects many people, especially in developing countries. Despite several advances that have been made in diagnosis and treatment, the morbidity and mortality rates due to OSCC remain high. Accumulating evidence indicates that aberrant activation of cellular signaling pathways, such as the Notch, Wnt and Hedgehog pathways, occurs during the development and metastasis of OSCC. In this review, we have articulated the roles of the Notch, Wnt and Hedgehog signaling pathways in OSCC and their crosstalk during tumor development and progression. We have also examined possible interactions and associations between these pathways and treatment regimens that could be employed to effectively tackle OSCC and/or prevent its recurrence.

CONCLUSIONS

Activation of the Notch signaling pathway upregulates the expression of several genes, including c-Myc, β-catenin, NF-κB and Shh. Associations between the Notch signaling pathway and other pathways have been shown to enhance OSCC tumor aggressiveness. Crosstalk between these pathways supports the maintenance of cancer stem cells (CSCs) and regulates OSCC cell motility. Thus, application of compounds that block these pathways may be a valid strategy to treat OSCC. Such compounds have already been employed in other types of cancer and could be repurposed for OSCC.

Dietary Phytochemicals as a Potential Source for Targeting Cancer Stem Cells

The tumor microenvironment is composed of various types of cells that lead to tumor heterogeneity. In the middle of these populations, cancer stem cells play a vital role in the initiation and progression of cancer cells and are capable of self-renewal and differentiation processes. These cancer stem cells are resistant to conventional therapy such as chemotherapy and radiotherapy. To eradicate the cancer stem cells in the tumor environment, various natural product has been found in recent years. In this review, we have selected some of the natural products based on anticancer potential including targeting cancer cells and cancer stem cells. Further, this review explains the molecular mechanism of action of these natural products in various cancer stem cells. Therefore, targeting a multi-drug resistant cancer stem cell by natural products is a novel method to reduce drug resistance and adverse effect during conventional therapy.

LncRNAs and microRNAs as Essential Regulators of Stemness in Breast Cancer Stem Cells

Breast cancer is an aggressive disease with a high incidence in women worldwide. Two decades ago, a controversial hypothesis was proposed that cancer arises from a subpopulation of “tumor initiating cells” or “cancer stem cells-like” (CSC). Today, CSC are defined as small subset of somatic cancer cells within a tumor with self-renewal properties driven by the aberrant expression of genes involved in the maintenance of a stemness-like phenotype. The understanding of the underlying cellular and molecular mechanisms involved in the maintenance of CSC subpopulation are fundamental in the development and persistence of breast cancer. Nowadays, the hypothesis suggests that genetic and epigenetic alterations give rise to breast cancer stem cells (bCSC), which are responsible for self-renewal, tumor growth, chemoresistance, poor prognosis and low survival in patients. However, the prominence of bCSC, as well as the molecular mechanisms that regulates and promotes the malignant phenotypes, are still poorly understood. The role of non-coding RNAs (ncRNAs), such as long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) acting as oncogenes or tumor suppressor genes has been recently highlighted by a plethora of studies in breast cancer. These ncRNAs positively or negatively impact on different signaling pathways that govern the cancer hallmarks associated with bCSC, making them attractive targets for therapy. In this review, we present a current summary of the studies on the pivotal roles of lncRNAs and microRNAs in the regulation of genes associated to stemness of bCSC.

Systems Pharmacology-Based Strategy to Explore the Pharmacological Mechanisms of Citrus Peel (Chenpi) for Treating Complicated Diseases

Citri Reticulatae Pericarpium (CRP), also known as Chenpi in Chinese, is the dry mature peel of Citrus reticulata Blanco or its cultivated varieties. CRP as the health-care food and dietary supplement has been widely used in various diseases. However, the potential pharmacological mechanisms of CRP to predict and treat various diseases have not yet been fully elucidated. A systems pharmacology-based approach is developed by integrating absorption, distribution, metabolism, and excretion screening, multiple target fishing, network pharmacology, as well as pathway analysis to comprehensively dissect the potential mechanism of CRP for therapy of various diseases. The results showed that 39 bioactive components and 121 potential protein targets were identified from CRP. The 121 targets are closely related to various diseases of the cardiovascular system, respiratory system, gastrointestinal system, etc. These targets are further mapped to compound-target, target-disease, and target-pathway networks to clarify the therapeutic mechanism of CRP at the system level. The current study sheds light on a promising way for promoting the discovery of new botanical drugs.

The importance of Ras in drug resistance in cancer

In this review, we analyse the impact of oncogenic Ras mutations in mediating cancer drug resistance and the progress made in the abrogation of this resistance, through pharmacological targeting. At a physiological level, Ras is implicated in many cellular proliferation and survival pathways. However, mutations within this small GTPase can be responsible for the initiation of cancer, therapeutic resistance and failure, and ultimately disease relapse. Often termed "undruggable," Ras is notoriously difficult to target directly, due to its structure and intrinsic activity. Thus, Ras-mediated drug resistance remains a considerable pharmacological problem. However, with advances in both analytical techniques and novel drug classes, the therapeutic landscape against Ras is changing. Allele-specific, direct Ras-targeting agents have reached clinical trials for the first time, indicating there may, at last, be hope of targeting such an elusive but significant protein for better more effective cancer therapy.

The Breast Cancer Stem Cells Traits and Drug Resistance

Drug resistance is a major challenge in breast cancer (BC) treatment at present. Accumulating studies indicate that breast cancer stem cells (BCSCs) are responsible for the BC drugs resistance, causing relapse and metastasis in BC patients. Thus, BCSCs elimination could reverse drug resistance and improve drug efficacy to benefit BC patients. Consequently, mastering the knowledge on the proliferation, resistance mechanisms, and separation of BCSCs in BC therapy is extremely helpful for BCSCs-targeted therapeutic strategies. Herein, we summarize the principal BCSCs surface markers and signaling pathways, and list the BCSCs-related drug resistance mechanisms in chemotherapy (CT), endocrine therapy (ET), and targeted therapy (TT), and display therapeutic strategies for targeting BCSCs to reverse drug resistance in BC. Even more importantly, more attention should be paid to studies on BCSC-targeted strategies to overcome the drug resistant dilemma of clinical therapies in the future.

Pathophysiological relationship between hypoxia associated oxidative stress, Epithelial-mesenchymal transition, stemness acquisition and alteration of Shh/ Gli-1 axis during oral sub-mucous fibrosis and oral squamous cell carcinoma

Oral sub-mucous fibrosis (OSF) is a pathophysiological state of oral cavity or oropharynx having a high chance of conversion to oral squamous cell carcinoma (OSCC). It involves fibrotic transformation of sub-epithelial matrix along with epithelial abnormalities. The present work aims to unveil the mechanistic domain regarding OSF to OSCC conversion exploring the scenario of hypoxia associated oxidative stress, epithelial-mesenchymal transition (EMT), metastasis and stemness acquisition. The study involves histopathological analysis of the diseased condition along with the exploration of oxidative stress status, assessment of mitochondrial condition, immunohistochemical analysis of HIF-1α, E-cadherin, vimentin, ERK, ALDH-1, CD133, Shh, Gli-1 and survivin expressions in the oral epithelial region together with the quantitative approach towards collagen deposition in the sub-epithelial matrix. Oxidative stress was found to be associated with type-II EMT in case of OSF attributing the development of sub-epithelial fibrosis and type-III EMT in case of OSCC favoring malignancy associated metastasis. Moreover, the acquisition of stemness during OSCC can also be correlated with EMT. Alteration of Shh and Gli-1 expression pattern revealed the mechanistic association of hypoxia with the phenotypic plasticity and disease manifestation in case of OSF as well as OSCC. Shh/ Gli-1 signaling can also be correlated with survivin mediated cytoprotective phenomenon under oxidative stress. Overall, the study established the correlative network of hypoxia associated oxidative stress, EMT and manifestation of oral pre-cancerous and cancerous condition in a holistic approach that may throw rays of hope in the therapeutic domain of the concerned diseases.

Targeting the Wnt/β-catenin signaling pathway in cancer

The aberrant Wnt/β-catenin signaling pathway facilitates cancer stem cell renewal, cell proliferation and differentiation, thus exerting crucial roles in tumorigenesis and therapy response. Accumulated investigations highlight the therapeutic potential of agents targeting Wnt/β-catenin signaling in cancer. Wnt ligand/ receptor interface, β-catenin destruction complex and TCF/β-catenin transcription complex are key components of the cascade and have been targeted with interventions in preclinical and clinical evaluations. This scoping review aims at outlining the latest progress on the current approaches and perspectives of Wnt/β-catenin signaling pathway targeted therapy in various cancer types. Better understanding of the updates on the inhibitors, antagonists and activators of Wnt/β-catenin pathway rationalizes innovative strategies for personalized cancer treatment. Further investigations are warranted to confirm precise and secure targeted agents and achieve optimal use with clinical benefits in malignant diseases.

Characteristics of TGFBR1-EGFR-CTNNB1-CDH1 Signaling Axis in Wnt-Regulated Invasion and Migration in Lung Cancer

This study aimed to explore the characteristics of TGFBR1-epidermal growth factor receptor (EGFR)-CTNNB1-CDH1 axis in regulating the invasion and migration in lung cancer. Using the small interfering RNA technology, EGFR was silenced in H2170 and H1299 cells. Then, the colony formation, migration, and invasion abilities were detected using colony-forming assay and transwell assay. Moreover, the mRNA expression of smad2, smad3, CTNNB1, and CDH1, and the protein expression of TGFBR1, CDH1, and TCF were determined using the real-time polymerase chain reaction and western blotting. The results showed that silencing EGFR could significantly decrease the colony-forming ability in H2170 and H1299. Knocking down EGFR could significantly inhibit the invasion and migration ability of H2179 and H1299. Inhibiting the expression of EGFR could significantly decrease the expression of smad2, smad3, CDH1, and CTNNB1, with all P-values <0.05. In addition, silencing EGFR could markedly decrease the expression of TGFBR1 and CDH1 in H1299 and H2170, with all P-values <0.05. In conclusion, silencing EGFR could significantly regulate the progression of lung cancer via TGFBR1-EGFR-CTNNB1-CDH1 axis in Wnt signaling pathway.

Increasing the colon cancer cells sensitivity toward radiation therapy via application of Oct4-Sox2 complex decoy oligodeoxynucleotides

Low sensitivity of cancer stem cells toward regular cancer therapy strategies is an important issue in the field of cancer remedy. The concept of cancer stem cell elimination has been a topic of interest in the field of molecular medicine for a long time. At the current study, it was aimed to elevate the sensitivity of cancer stem-like cells toward radiotherapy by treating with Oct4-Sox2 complex decoy oligodeoxynucleotides (ODNs). After treating HT29 and HT29-ShE cells with Oct4-Sox2 complex decoy ODNs, and analyzing the cellular uptake and localization of decoys, treated cells and control groups were subjected to irradiation by fractionated 6MV X-ray with a final dose of 2 Gy. Thereafter, the influence of radiotherapy on ODNs treated groups and control group was investigated on cell viability, cell cycle, apoptosis, colonosphere formation and scratch assay. Cellular uptake and localization assays demonstrated that decoy ODNs can efficiently be transfected to the cells and reside in subcellular compartment, where they pose their action on gene regulation. Post radiotherapy analysis indicated statistical significance in decoy ODNs treated cells by means of lower cell viability, cell cycle arrest in G2/M phase, increased cellular apoptosis, and reduced cell motility. Also, formed colonospheres were smaller in size and fewer in numbers. Considering the role of Oct4, and Sox2 transcription factors in signaling pathways of preserving stemness and inducing reverse EMT, application of decoy strategy could increase the sensitivity of cancer cells toward irradiation, which has a potential to eliminate the cancerous cells from tumors and support cancer treatment.

Epigenetic Regulation of Cancer Stem Cells by the Aryl Hydrocarbon Receptor Pathway

Compelling evidence has demonstrated that tumor bulk comprises distinctive subset of cells generally referred as cancer stem cells (CSCs) that have been proposed as a strong sustainer and promoter of tumorigenesis and therapeutic resistance. These distinguished properties of CSCs have raised interest in understanding the molecular mechanisms that govern the maintenance of these cells. Numerous experimental and epidemiological studies have demonstrated that exposure to environmental toxins such as the polycyclic aromatic hydrocarbons (PAHs) is strongly involved in cancer initiation and progression. The PAH-induced carcinogenesis is shown to be mediated through the activation of a cytosolic receptor, aryl hydrocarbon receptor (AhR)/Cytochrome P4501A pathway, suggesting a possible direct link between AhR and CSCs. Several recent studies have investigated the role of AhR in CSCs self-renewal and maintenance, however the molecular mechanisms and particularly the epigenetic regulations of CSCs by the AhR/CYP1A pathway have not been reviewed before. In this review, we first summarize the crosstalk between AhR and cancer genetics, with a particular emphasis on the mechanisms relevant to CSCs such as Wnt/β-catenin, Notch, NF-κB, and PTEN-PI3K/Akt signaling pathways. The second part of this review discusses the recent advances and studies highlighting the epigenetic mechanisms mediated by the AhR/CYP1A pathway that control CSC gene expression, self-renewal, and chemoresistance in various human cancers. Furthermore, the review also sheds light on the importance of targeting the epigenetic pathways as a novel therapeutic approach against CSCs.

Colorectal Cancer Stem Cells in the Progression to Liver Metastasis

Colorectal carcinoma (CRC) is a leading cause of cancer mortality. Tumorigenesis is a dynamic process wherein cancer stem cells (CSCs) and their microenvironment promote initiation, progression, and metastasis. Metastatic colonization is an inefficient process that is very complex and is poorly understood; however, in most cases, metastatic disease is not curable, and resistance mechanisms tend to develop against conventional treatments. An understanding of the underlying mechanisms and factors that contribute to the development of metastasis in CRC can aid in the search for specific therapeutic targets for improving standard treatments. In this review, we summarize current knowledge regarding tumor biology and the use of stroma cells as prognostic factors and inflammatory inducers associated with the use of tumor microenvironments as a promoter of cancer metastasis. Moreover, we look into the importance of CSC, pericytes, and circulating tumor cells as mechanisms that lead to liver metastasis, and we also focus on the cellular and molecular pathways that modulate and regulate epithelial–mesenchymal transition. Finally, we discuss a novel therapeutic target that can potentially eliminate CSCs as a CRC treatment.

Novel strategies to target chemoresistant triple-negative breast cancer

Previous studies from our group and others have shown that current drug treatment(s) strategies eliminate bulk of tumor cells (non-CSCs) but it had a minimal effect on cancer stem cells (CSCs) leading to resistance and tumor recurrence. We studied the effects of CFM-4.16 (CARP-1 functional mimetic) and/or cisplatin on four Triple-negative breast cancer (TNBC) MDA-MB-468, MDA-MB-231, CRL-2335 and BR-1126, two cisplatin resistant CisR/MDA-231 and CisR/MDA-468 and cancer stem cells (CSCs) from resistant cell lines. TNBC cells treated with CFM-4.16 plus cisplatin inhibited the expression of FZD8, LRP6 and c-Myc and significantly enhanced cell death in all the cell lines by ~70%-80% compared with the control(s). When Cisplatin resistant CisR/MDA-231 and CisR/MDA-468 were treated with CFM-4.16 plus cisplatin, they also showed a reduction in FZD8 and LRP6 and increased apoptosis compared to control group. Similarly, CFM-4.16 plus cisplatin treatment reduced mammospheres formation abilities of CSCs by 80-90% compared to control group, increased PARP cleavage and apoptosis. Data shows CFM-4.16 plus cisplatin treatment significantly increased apoptosis/cell death in parental, cisplatin resistant and CSCs. Taken together the data suggests that FZD8-mediated Wnt-signaling plays a major role in mediating CSCs growth and resistance to chemotherapy and its inhibition enhances the chemotherapeutic response in TNBC.