A microRNA miR-34a-regulated bimodal switch targets Notch in colon cancer stem cells

LncRNAs and asymmetric cell division: the epigenetic mechanisms

Asymmetric cell division (ACD) plays a pivotal role in development, tissue homeostasis, and stem cell maintenance. Emerging evidence suggests that long non-coding RNAs (lncRNAs) are key regulators of ACD, orchestrating the intricate molecular machinery that governs cell fate determination. This review summarizes current literature to elucidate the diverse roles of lncRNAs in modulating ACD across various biological contexts. The regulatory mechanisms of asymmetric cell division mediated by lncRNAs, including their interactions with protein effectors, epigenetic regulation, and subcellular localization are explored. Additionally, we discuss the implications of dysregulated lncRNAs in mediating ACD that lead to tumorigenesis. By integrating findings from diverse experimental models and cell types, this review provides insights into the multifaceted roles of lncRNAs in governing asymmetric cell division, shedding light on fundamental biological processes. Further research in this area may lead to the development of novel therapies targeting dysregulated lncRNAs to restore proper cell division and function. The knowledge of lncRNAs regulating ACD could potentially revolutionize the field of regenerative medicine and cancer therapy by targeting specific lncRNAs involved in ACD. By unraveling the complex interactions between lncRNAs and cellular processes, the potential novel opportunities for precision medicine approaches may be uncovered.

The epigenetic landscape in intestinal stem cells and its deregulation in colorectal cancer

Epigenetic mechanisms play a pivotal role in controlling gene expression and cellular plasticity in both normal physiology and pathophysiological conditions. These mechanisms are particularly important in the regulation of stem cell self-renewal and differentiation, both in embryonic development and within adult tissues. A prime example of this finely tuned epigenetic control is observed in the gastrointestinal lining, where the small intestine undergoes renewal approximately every 3-5 days. How various epigenetic mechanisms modulate chromatin functions in intestinal stem cells (ISCs) is currently an active area of research. In this review, we discuss the main epigenetic mechanisms that control ISC differentiation under normal homeostasis. Furthermore, we explore the dysregulation of these mechanisms in the context of colorectal cancer (CRC) development. By outlining the main epigenetic mechanisms contributing to CRC, we highlight the recent therapeutics development and future directions for colorectal cancer research.

MicroRNA-34 and gastrointestinal cancers: a player with big functions

It is commonly assumed that gastrointestinal cancer is the most common form of cancer across the globe and is the leading contributor to cancer-related death. The intricate mechanisms underlying the growth of GI cancers have been identified. It is worth mentioning that both non-coding RNAs (ncRNAs) and certain types of RNA, such as circular RNAs (circRNAs), long non-coding RNAs (lncRNAs), and microRNAs (miRNAs), can have considerable impact on the development of gastrointestinal (GI) cancers. As a tumour suppressor, in the group of short non-coding regulatory RNAs is miR-34a. miR-34a silences multiple proto-oncogenes at the post-transcriptional stage by targeting them, which inhibits all physiologically relevant cell proliferation pathways. However, it has been discovered that deregulation of miR-34a plays important roles in the growth of tumors and the development of cancer, including invasion, metastasis, and the tumor-associated epithelial-mesenchymal transition (EMT). Further understanding of miR-34a's molecular pathways in cancer is also necessary for the development of precise diagnoses and effective treatments. We outlined the most recent research on miR-34a functions in GI cancers in this review. Additionally, we emphasize the significance of exosomal miR-34 in gastrointestinal cancers.

Cancer resistance and metastasis are maintained through oxidative phosphorylation

Malignant tumors have increased energy requirements due to growth, differentiation or response to stress. A significant number of studies in recent years have described upregulation of mitochondrial genes responsible for oxidative phosphorylation (OXPHOS) in some tumors. Although OXPHOS is replaced by glycolysis in some tumors (Warburg effect), both processes can occur simultaneously during the evolution of the same malignancies. In particular, chemoresistant and/or cancer stem cells appear to find a way to activate OXPHOS and metastasize. In this paper, we discuss recent work showing upregulation of OXPHOS in chemoresistant tumors and cell models. In addition, we show an inverse correlation of OXPHOS gene expression with the survival time of cancer patients after chemotherapy and discuss combination therapies for resistant tumors.

Combinatorial Cooperativity in miR200-Zeb Feedback Network can Control Epithelial-Mesenchymal Transition

Carcinomas often utilize epithelial-mesenchymal transition (EMT) programs for cancer progression and metastasis. Numerous studies report SNAIL-induced miR200/Zeb feedback circuit as crucial in regulating EMT by placing cancer cells in at least three phenotypic states, viz. epithelial (E), hybrid (h-E/M), mesenchymal (M), along the E-M phenotypic spectrum. However, a coherent molecular-level understanding of how such a tiny circuit controls carcinoma cell entrance into and residence in various states is lacking. Here, we use molecular binding data and mathematical modeling to report that the miR200/Zeb circuit can essentially utilize combinatorial cooperativity to control E-M phenotypic plasticity. We identify minimal combinatorial cooperativities that give rise to E, h-E/M, and M phenotypes. We show that disrupting a specific number of miR200 binding sites on Zeb as well as Zeb binding sites on miR200 can have phenotypic consequences-the circuit can dynamically switch between two (E, M) and three (E, h-E/M, M) phenotypes. Further, we report that in both SNAIL-induced and SNAIL knock-out miR200/Zeb circuits, cooperative transcriptional feedback on Zeb as well as Zeb translation inhibition due to miR200 are essential for the occurrence of intermediate h-E/M phenotype. Finally, we demonstrate that SNAIL can be dispensable for EMT, and in the absence of SNAIL, the transcriptional feedback can control cell state transition from E to h-E/M, to M state. Our results thus highlight molecular-level regulation of EMT in miR200/Zeb circuit and we expect these findings to be crucial to future efforts aiming to prevent EMT-facilitated dissemination of carcinomas.

The contribution of asymmetric cell division to phenotypic heterogeneity in cancer

Cells have evolved intricate mechanisms for dividing their contents in the most symmetric way during mitosis. However, a small proportion of cell divisions results in asymmetric segregation of cellular components, which leads to differences in the characteristics of daughter cells. Although the classical function of asymmetric cell division (ACD) in the regulation of pluripotency is the generation of one differentiated daughter cell and one self-renewing stem cell, recent evidence suggests that ACD plays a role in other physiological processes. In cancer, tumor heterogeneity can result from the asymmetric segregation of genetic material and other cellular components, resulting in cell-to-cell differences in fitness and response to therapy. Defining the contribution of ACD in generating differences in key features relevant to cancer biology is crucial to advancing our understanding of the causes of tumor heterogeneity and developing strategies to mitigate or counteract it. In this Review, we delve into the occurrence of asymmetric mitosis in cancer cells and consider how ACD contributes to the variability of several phenotypes. By synthesizing the current literature, we explore the molecular mechanisms underlying ACD, the implications of phenotypic heterogeneity in cancer, and the complex interplay between these two phenomena.

Asymmetric division of stem cells and its cancer relevance

Asymmetric division is a fundamental process for generating cell diversity and maintaining the stem cell population. During asymmetric division, proteins, organelles, and even RNA are distributed unequally between the two daughter cells, determining their distinct cell fates. The mechanisms orchestrating this process are extremely complex. Dysregulation of asymmetric division can potentially trigger cancer progression. Cancer stem cells, in particular, undergo asymmetric division, leading to intra-tumoral heterogeneity, which contributes to treatment refractoriness. In this review, we delve into the cellular and molecular mechanisms that govern asymmetric division and explore its relevance to tumorigenesis.

The potential relevance of long non-coding RNAs in colorectal cancer pathogenesis and treatment: A review focus on signaling pathways

Colorectal cancer (CRC) is one of the most frequent cancers in incidence and mortality. Despite advances in cancer biology, molecular genetics, and targeted treatments, CRC prognosis and survival have not kept pace. This is usually due to advanced staging and metastases at diagnosis. Thus, great importance has been placed upon understanding the molecular pathophysiology behind the development of CRC, which has highlighted the significance of non-coding RNA's role and associated intracellular signaling pathways in the pathogenesis of the disease. According to recent studies, long non-coding RNAs (lncRNA), a subtype of ncRNAs whose length exceeds 200 nucleotides, have been found to have regulatory functions on multiple levels. Their actions at the transcription, post-transcriptional, translational levels, and epigenetic regulation have made them prime modulators of gene expression. Due to their role in cellular cancer hallmarks, their dysregulation has been linked to several illnesses, including cancer. Furthermore, their clinical relevance has expanded due to their possible detection in blood which has cemented them as potential future biomarkers and thus, potential targets for new therapy. This review will highlight the importance of lncRNAs and related signaling pathways in the development of CRC and their subsequent clinical applications.

A concise review on miRNAs as regulators of colon cancer stem cells and associated signalling pathways

Despite recent therapy advances and a better understanding of colon cancer biology, it remains one of the major causes of death. The cancer stem cells, associated with the progression, metastasis, and recurrence of colon cancer, play a major role in promoting the development of tumour and are found to be chemo resistant. The stroma of the tumour, which makes up the bulk of the tumour mass, is composed of the tumour microenvironment. With the advent of theranostic and the development of personalised medicine, miRNAs are becoming increasingly important in the context of colon malignancies. A holistic understanding of the regulatory roles of miRNAs in cancer cells and cancer stem cells will allow us to design effective strategies to regulate miRNAs, which could lead to improved clinical translation and creating a potent colon cancer treatment strategy. In this review paper, we briefly discuss the history of miRNA as well as the mechanisms of miRNA and cancer stem cells that contribute to the tumour growth, apoptosis, and advancement of colon cancer. The usefulness of miRNA in colorectal cancer theranostic is further concisely reviewed. We conclude by holding a stance in addressing the prospects and possibilities for miRNA by the disclosure of recent theranostic approaches aimed at eradicating cancer stem cells and enhancing overall cancer treatment outcomes.

Extirpating the cancer stem cell hydra: Differentiation therapy and Hyperthermia therapy for targeting the cancer stem cell hierarchy

Ever since the discovery of cancer stem cells (CSCs), they have progressively attracted more attention as a therapeutic target. Like the mythical hydra, this subpopulation of cells seems to contribute to cancer immortality, spawning more cells each time that some components of the cancer cell hierarchy are destroyed. Traditional modalities focusing on cancer treatment have emphasized apoptosis as a route to eliminate the tumor burden. A major problem is that cancer cells are often in varying degrees of dedifferentiation contributing to what is known as the CSCs hierarchy and cells which are known to be resistant to conventional therapy. Differentiation therapy is an experimental therapeutic modality aimed at the conversion of malignant phenotype to a more benign one. Hyperthermia therapy (HT) is a modality exploiting the changes induced in cells by the application of heat produced to aid in cancer therapy. While differentiation therapy has been successfully employed in the treatment of acute myeloid leukemia, it has not been hugely successful for other cancer types. Mounting evidence suggests that hyperthermia therapy may greatly augment the effects of differentiation therapy while simultaneously overcoming many of the hard-to-treat facets of recurrent tumors. This review summarizes the progress made so far in integrating hyperthermia therapy with existing modules of differentiation therapy. The focus is on studies related to the successful application of both hyperthermia and differentiation therapy when used alone or in conjunction for hard-to-treat cancer cell niche with emphasis on combined approaches to target the CSCs hierarchy.

Notch receptor/ligand diversity: contribution to colorectal cancer stem cell heterogeneity

Cancer cell heterogeneity is a key contributor to therapeutic failure and post-treatment recurrence. Targeting cell subpopulations responsible for chemoresistance and recurrence seems to be an attractive approach to improve treatment outcome in cancer patients. However, this remains challenging due to the complexity and incomplete characterization of tumor cell subpopulations. The heterogeneity of cells exhibiting stemness-related features, such as self-renewal and chemoresistance, fuels this complexity. Notch signaling is a known regulator of cancer stem cell (CSC) features in colorectal cancer (CRC), though the effects of its heterogenous signaling on CRC cell stemness are only just emerging. In this review, we discuss how Notch ligand-receptor specificity contributes to regulating stemness, self-renewal, chemoresistance and cancer stem cells heterogeneity in CRC.

Recent insights into the nutritional immunomodulation of cancer-related microRNAs

Cancer is the most common cause of death worldwide, following cardiovascular diseases. Cancer is a multifactorial disease and many reasons such as physical, chemical, biological, and lifestyle-related factors. Nutrition, which is one of the various factors that play a role in the prevention, development, and treatment of many types of cancer, affects the immune system, which is characterized by disproportionate pro-inflammatory signaling in cancer. Studies investigating the molecular mechanisms of this effect have shown that foods rich in bioactive compounds, such as green tea, olive oil, turmeric, and soybean play a significant role in positively changing the expression of miRNAs involved in the regulation of genes associated with oncogenic/tumor-suppressing pathways. In addition to these foods, some diet models may change the expression of specific cancer-related miRNAs in different ways. While Mediterranean diet has been associated with anticancer effects, a high-fat diet, and a methyl-restricted diet are considered to have negative effects. This review aims to discuss the effects of specific foods called "immune foods," diet models, and bioactive components on cancer by changing the expression of miRNAs in the prevention and treatment of cancer.

Targeting intratumor heterogeneity suppresses colorectal cancer chemoresistance and metastasis

Intratumor heterogeneity (ITH) is a barrier to effective therapy. However, it is largely unknown how ITH is established at the onset of tumor progression, such as in colorectal cancer (CRC). Here, we integrate single-cell RNA-seq and functional validation to show that asymmetric division of CRC stem-like cells (CCSC) is critical for early ITH establishment. We find that CCSC-derived xenografts contain seven cell subtypes, including CCSCs, that dynamically change during CRC xenograft progression. Furthermore, three of the subtypes are generated by asymmetric division of CCSCs. They are functionally distinct and appear at the early stage of xenografts. In particular, we identify a chemoresistant and an invasive subtype, and investigate the regulators that control their generation. Finally, we show that targeting the regulators influences cell subtype composition and CRC progression. Our findings demonstrate that asymmetric division of CCSCs contributes to the early establishment of ITH. Targeting asymmetric division may alter ITH and benefit CRC therapy.

YY2-DRP1 Axis Regulates Mitochondrial Fission and Determines Cancer Stem Cell Asymmetric Division

Cancer stem cells (CSCs) are associated with tumor progression, recurrence, and therapeutic resistance. To maintain their pool while promoting tumorigenesis, CSCs divide asymmetrically, producing a CSC and a highly proliferative, more differentiated transit-amplifying cell. Exhausting the CSC pool has been proposed as an effective antitumor strategy; however, the mechanism underlying CSC division remains poorly understood, thereby largely limiting its clinical application. Here, through cross-omics analysis, yin yang 2 (YY2) is identified as a novel negative regulator of CSC maintenance. It is shown that YY2 is downregulated in stem-like tumor spheres formed by hepatocarcinoma cells and in liver cancer, in which its expression is negatively correlated with disease progression and poor prognosis. Furthermore, it is revealed that YY2 overexpression suppressed liver CSC asymmetric division, leading to depletion of the CSC pool and decreased tumor-initiating capacity. Meanwhile, YY2 knock-out in stem-like tumor spheres caused enrichment in mitochondrial functions. Mechanistically, it is revealed that YY2 impaired mitochondrial fission, and consequently, liver CSC asymmetric division, by suppressing the transcription of dynamin-related protein 1. These results unravel a novel regulatory mechanism of mitochondrial dynamic-mediated CSCs asymmetric division and highlight the role of YY2 as a tumor suppressor and a therapeutic target in antitumor treatment.

A role for partial epithelial-to-mesenchymal transition in enabling stemness in homeostasis and cancer

Stem cells have self-renewal capacities and the ability to give rise to differentiated cells thereby sustaining tissues during homeostasis and injury. This structural hierarchy extends to tumours which harbor stem-like cells deemed cancer stem cells that propagate the tumour and drive metastasis and relapse. The process of epithelial-to-mesenchymal transition (EMT), which plays an important role in development and cancer cell migration, was shown to be correlated with stemness in both homeostasis and cancer indicating that stemness can be acquired and is not necessarily an intrinsic trait. Nowadays it is experimentally proven that the activation of an EMT program does not necessarily drive cells towards a fully mesenchymal phenotype but rather to hybrid E/M states. This review offers the latest advances in connecting the EMT status and stem-cell state of both non-transformed and cancer cells. Recent literature clearly shows that hybrid EMT states have a higher probability of acquiring stem cell traits. The position of a cell along the EMT-axis which coincides with a stem cell-like state is known as the stemness window. We show how the original EMT-state of a cell dictates the EMT/MET inducing programmes required to reach stemness. Lastly we present the mechanism of stemness regulation and the regulatory feedback loops which position cells at a certain EMT state along the EMT axis.

Cancer stem cells in colorectal cancer: Signaling pathways involved in stemness and therapy resistance

Colorectal cancer (CRC) is the third cause of cancer death worldwide. Although, in some cases, treatment can increase patient survival and reduce cancer recurrence, in many cases, tumors can develop resistance to therapy leading to recurrence. One of the main reasons for recurrence and therapy resistance is the presence of cancer stem cells (CSCs). CSCs possess a self-renewal ability, and their stemness properties lead to the avoidance of apoptosis, and allow a new clone of cancer cells to emerge. Numerous investigations inidicated the involvment of cellular signaling pathways in embryonic development, and growth, repair, and maintenance of tissue homeostasis, also participate in the generation and maintenance of stemness in colorectal CSCs. This review discusses the role of Wnt, NF-κB, PI3K/AKT/mTOR, Sonic hedgehog, and Notch signaling pathways in colorectal CSCs, and the possible modulating drugs that could be used in treatment for resistant CRC.

Distinct but interchangeable subpopulations of colorectal cancer cells with different growth fates and drug sensitivity

Dynamic changes in cell properties lead to intratumor heterogeneity; however, the mechanisms of nongenetic cellular plasticity remain elusive. When the fate of each cell from colorectal cancer organoids was tracked through a clonogenic growth assay, the cells showed a wide range of growth ability even within the clonal organoids, consisting of distinct subpopulations; the cells generating large spheroids and the cells generating small spheroids. The cells from the small spheroids generated only small spheroids (S-pattern), while the cells from the large spheroids generated both small and large spheroids (D-pattern), both of which were tumorigenic. Transition from the S-pattern to the D-pattern occurred by various extrinsic triggers, in which Notch signaling and Musashi-1 played a key role. The S-pattern spheroids were resistant to chemotherapy and transited to the D-pattern upon drug treatment through Notch signaling. As the transition is linked to the drug resistance, it can be a therapeutic target.

Cancer Stem Cells: Biology and Therapeutic Implications

It is well recognized that most cancers derive and progress from transformation and clonal expansion of a single cell that possesses stem cell properties, i.e., self-renewal and multilineage differentiation capacities. Such cancer stem cells (CSCs) are usually present at very low frequencies and possess properties that make them key players in tumor development. Indeed, besides having the ability to initiate tumor growth, CSCs drive tumor progression and metastatic dissemination, are resistant to most cancer drugs, and are responsible for cancer relapse. All of these features make CSCs attractive targets for the development of more effective oncologic treatments. In the present review article, we have summarized recent advances in the biology of CSCs, including their identification through their immunophenotype, and their physiology, both in vivo and in vitro. We have also analyzed some molecular markers that might become targets for developing new therapies aiming at hampering CSCs regeneration and cancer relapse.

Cancer Stem Cells-The Insight into Non-Coding RNAs

Since their initial identification three decades ago, there has been extensive research regarding cancer stem cells (CSCs). It is important to consider the biology of cancer stem cells with a particular focus on their phenotypic and metabolic plasticity, the most important signaling pathways, and non-coding RNAs (ncRNAs) regulating these cellular entities. Furthermore, the current status of therapeutic approaches against CSCs is an important consideration regarding employing the technology to improve human health. Cancer stem cells have claimed to be one of the most important group of cells for the development of several common cancers as they dictate features, such as resistance to radio- and chemotherapy, metastasis, and secondary tumor formation. Therapies which could target these cells may develop into an effective strategy for tumor eradication and a hope for patients for whom this disease remains uncurable.

Notch-associated lncRNAs profiling circuiting epigenetic modification in colorectal cancer

Background

Colorectal cancer (CRC) is one of the most prevalent digestive cancers, ranking the 2nd cause of cancer-related fatality worldwide. The worldwide burden of CRC is predicted to rise by 60% by 2030. Environmental factors drive, first, inflammation and hence, cancer incidence increase.

Main

The Notch-signaling system is an evolutionarily conserved cascade, has role in the biological normal developmental processes as well as malignancies. Long non-coding RNAs (LncRNAs) have become major contributors in the advancement of cancer by serving as signal pathways regulators. They can control gene expression through post-translational changes, interactions with micro-RNAs or down-stream effector proteins. Recent emerging evidence has emphasized the role of lncRNAs in controlling Notch-signaling activity, regulating development of several cancers including CRC.

Conclusion

Notch-associated lncRNAs might be useful prognostic biomarkers or promising potential therapeutic targets for CRC treatment.

Therefore, here-in we will focus on the role of “Notch-associated lncRNAs in CRC” highlighting “the impact of Notch-associated lncRNAs as player for cancer induction and/or progression.”

Graphical Abstract

Concise review: Cancer cell reprogramming and therapeutic implications

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The cancer stem cell (CSC) act as tumor initiating cells.

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Reprogramming technology can convert cells into CSCs.

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Metabolic reprogramming is critical for CSCs.

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MiRNA can mediate cancer cell reprogramming as emerging alternatives.

The cancer stem cell (CSC) hypothesis postulates that cancer originates from the malignant transformation of stem cells and is considered to apply to a variety of cancers. Additionally, cancer cells alter metabolic processes to sustain their characteristic uncontrolled growth and proliferation. Further, microRNAs (miRNAs) are found to be involved in acquisition of stem cell-like properties, regulation and reprogramming of cancer cells during cancer progression through its post-transcriptional-regulatory activity. In this concise review, we aim to integrate the current knowledge and recent advances to elucidate the mechanisms involved in the regulation of cell reprogramming and highlights the potential therapeutic implications for the future.

Panoramic view of microRNAs in regulating cancer stem cells

Cancer stem cells (CSCs) are a subgroup of tumor cells, possessing the abilities of self-renewal and generation of heterogeneous tumor cell lineages. They are believed to be responsible for tumor initiation, metastasis, as well as chemoresistance in human malignancies. MicroRNAs (miRNAs) are small noncoding RNAs that play essential roles in various cellular activities including CSC initiation and CSC-related properties. Mature miRNAs with ∼22 nucleotides in length are generated from primary miRNAs via its precursors by miRNA-processing machinery. Extensive studies have demonstrated that mature miRNAs modulate CSC initiation and stemness features by regulating multiple pathways and targeting stemness-related factors. Meanwhile, both miRNA precursors and miRNA-processing machinery can also affect CSC properties, unveiling a new insight into miRNA function. The present review summarizes the roles of mature miRNAs, miRNA precursors, and miRNA-processing machinery in regulating CSC properties with a specific focus on the related molecular mechanisms, and also outlines the potential application of miRNAs in cancer diagnosis, predicting prognosis, as well as clinical therapy.

Upregulation of BMI1-suppressor miRNAs (miR-200c, miR-203) during terminal differentiation of colon epithelial cells

BACKGROUND

MicroRNAs (miRNAs) are key regulators of stem cell functions, including self-renewal and differentiation. In this study, we aimed to identify miRNAs that are upregulated during terminal differentiation in the human colon epithelium, and elucidate their role in the mechanistic control of stem cell properties.

METHODS

"Bottom-of-the-crypt" (EPCAM⁺/CD44⁺/CD66a^low) and "top-of-the-crypt" (EPCAM⁺/CD44^neg/CD66a^high) epithelial cells from 8 primary colon specimens (6 human, 2 murine) were purified by flow cytometry and analyzed for differential expression of 335 miRNAs. The miRNAs displaying the highest upregulation in "top-of-the-crypt" (terminally differentiated) epithelial cells were tested for positive correlation and association with survival outcomes in a colon cancer RNA-seq database (n = 439 patients). The two miRNAs with the strongest "top-of-the-crypt" expression profile were evaluated for capacity to downregulate self-renewal effectors and inhibit in vitro proliferation of colon cancer cells, in vitro organoid formation by normal colon epithelial cells and in vivo tumorigenicity by patient-derived xenografts (PDX).

RESULTS

Six miRNAs (miR-200a, miR-200b, miR-200c, miR-203, miR-210, miR-345) were upregulated in "top-of-the-crypt" cells and positively correlated in expression among colon carcinomas. Overexpression of the three miRNAs with the highest inter-correlation coefficients (miR-200a, miR-200b, miR-200c) associated with improved survival. The top two over-expressed miRNAs (miR-200c, miR-203) cooperated synergistically in suppressing expression of BMI1, a key regulator of self-renewal in stem cell populations, and in inhibiting proliferation, organoid-formation and tumorigenicity of colon epithelial cells.

CONCLUSION

In the colon epithelium, terminal differentiation associates with the coordinated upregulation of miR-200c and miR-203, which cooperate to suppress BMI1 and disable the expansion capacity of epithelial cells.

Bioengineered miR-34a modulates mitochondrial inner membrane protein 17 like 2 (MPV17L2) expression toward the control of cancer cell mitochondrial functions

Genome-derived microRNAs (miRNAs or miRs) control post-transcriptional gene expression critical for various cellular processes. Recently, we have invented a novel platform technology to achieve high-yield production of fully humanized, bioengineered miRNA agents (hBERAs) for research and development. This study is aimed to produce and utilize a new biologic miR-34a-5p (or miR-34a) molecule, namely, hBERA/miR-34a, to delineate the role of miR-34a-5p in the regulation of mitochondrial functions in human carcinoma cells. Bioengineered hBERA/miR-34a was produced through in vivo fermentation production and purified by anion exchange fast protein liquid chromatography. hEBRA/miR-34a was processed to target miR-34a-5p in human osteosarcoma and lung cancer cells, as determined by selective stem-loop reverse transcription quantitative polymerase chain reaction analysis. The mitochondrial inner membrane protein MPV17 like 2 (MPV17L2) was validated as a direct target for miR-34a-5p by dual luciferase reporter assay. Western blot analysis revealed that bioengineered miR-34a-5p effectively reduced MPV17L2 protein outcomes, leading to much lower levels of respiratory chain Complex I activities and intracellular ATP that were determined with specific assay kits. Moreover, Seahorse Mito Stress Test assay was conducted, and the results showed that biologic miR-34a-5p sharply reduced cancer cell mitochondrial respiration capacity, accompanied by a remarkable increase of oxidative stress and elevated apoptotic cell death, which are manifested by greater levels of reactive oxygen species and selective apoptosis biomarkers, respectively. These results demonstrate the presence and involvement of the miR-34a-5p-MPV17L2 pathway in the control of mitochondrial functions in human carcinoma cells and support the utility of novel bioengineered miRNA molecules for functional studies.

Fusobacterium nucleatum Promotes Colorectal Cancer Cell to Acquire Stem Cell-Like Features by Manipulating Lipid Droplet-Mediated Numb Degradation

Fusobacterium nucleatum is a critical microbe that contributes to colorectal cancer progression and chemoresistance. However, whether and how F. nucleatum regulates colorectal cancer stem-like cells (CCSCs) remains unknown. Here, the authors show that F. nucleatum promotes CCSC self-renewal, and non-CCSCs to acquire CCSC features by manipulating cellular lipid accumulation. F. nucleatum infection decreases lipid accumulation in CCSCs by enhancing fatty acid oxidation, thus promoting CCSC self-renewal. In contrast, F. nucleatum increases lipid accumulation in non-CCSCs by promoting fatty acid formation. Lipids are deposited as lipid droplets, which recruits Numb, a key cell fate regulator, through the AP2A/ACSL3 complex, and MDM2, an E3 ubiquitin ligase, though VCP and UBXD8. On lipid droplets, Numb is degraded by MDM2, activating Notch signaling, thus promoting gain of stem-like cell features. Their findings demonstrate that F. nucleatum directly manipulates colorectal cancer cell fate and reveal the mechanism of lipid droplet-mediated Numb degradation for activating Notch signaling.

LncRNAs, the Molecules Involved in Communications With Colorectal Cancer Stem Cells

Colorectal cancer stem cells (CRCSCs) can actively self-renew, as well as having multidirectional differentiation and tumor regeneration abilities. Because the high functional activities of CRCSCs are associated with low cure rates in patients with colorectal cancer, efforts have sought to determine the function and regulatory mechanisms of CRCSCs. To date, however, the potential regulatory mechanisms of CRCSCs remain incompletely understood. Many non-coding genes are involved in tumor invasion and spread through their regulation of CRCSCs, with long non-coding RNAs (lncRNAs) being important non-coding RNAs. LncRNAs may be involved in the colorectal cancer development and drug resistance through their regulation of CRCSCs. This review systematically evaluates the latest research on the ability of lncRNAs to regulate CRCSC signaling pathways and the involvement of these lncRNAs in colorectal cancer promotion and suppression. The regulatory network of lncRNAs in the CRCSC signaling pathway has been determined. Further analysis of the potential clinical applications of lncRNAs as novel clinical diagnostic and prognostic biomarkers and therapeutic targets for colorectal cancer may provide new ideas and protocols for the prevention and treatment of colorectal cancer.

Nanoparticle-Based RNAi Therapeutics Targeting Cancer Stem Cells: Update and Prospective

Cancer stem cells (CSCs) are characterized by intrinsic self-renewal and tumorigenic properties, and play important roles in tumor initiation, progression, and resistance to diverse forms of anticancer therapy. Accordingly, targeting signaling pathways that are critical for CSC maintenance and biofunctions, including the Wnt, Notch, Hippo, and Hedgehog signaling cascades, remains a promising therapeutic strategy in multiple cancer types. Furthermore, advances in various cancer omics approaches have largely increased our knowledge of the molecular basis of CSCs, and provided numerous novel targets for anticancer therapy. However, the majority of recently identified targets remain ‘undruggable’ through small-molecule agents, whereas the implications of exogenous RNA interference (RNAi, including siRNA and miRNA) may make it possible to translate our knowledge into therapeutics in a timely manner. With the recent advances of nanomedicine, in vivo delivery of RNAi using elaborate nanoparticles can potently overcome the intrinsic limitations of RNAi alone, as it is rapidly degraded and has unpredictable off-target side effects. Herein, we present an update on the development of RNAi-delivering nanoplatforms in CSC-targeted anticancer therapy and discuss their potential implications in clinical trials.

The role of non-coding RNAs in chemotherapy for gastrointestinal cancers

Gastrointestinal (GI) cancers, including colorectal, gastric, hepatic, esophageal, and pancreatic tumors, are responsible for large numbers of deaths around the world. Chemotherapy is the most common approach used to treat advanced GI cancer. However, chemoresistance has emerged as a critical challenge that prevents successful tumor elimination, leading to metastasis and recurrence. Chemoresistance mechanisms are complex, and many factors and pathways are involved. Among these factors, non-coding RNAs (ncRNAs) are critical regulators of GI tumor development and subsequently can induce resistance to chemotherapy. This occurs because ncRNAs can target multiple signaling pathways, affect downstream genes, and modulate proliferation, apoptosis, tumor cell migration, and autophagy. ncRNAs can also induce cancer stem cell features and affect the epithelial-mesenchymal transition. Thus, ncRNAs could possibly act as new targets in chemotherapy combinations to treat GI cancer and to predict treatment response.

Poly (ADP-ribose) polymerase (PARP) inhibition in cancer: Potential impact in cancer stem cells and therapeutic implications

Inhibitors of poly(ADP-ribose) polymerase (PARP) are used in mono- or combination therapies for several malignancies. They are also used as maintenance therapy for some cancers after initial treatment. While the focus of this therapeutic approach is on the effect of PARP inhibition on the bulk tumour cells, in this review, we discuss their effect on the cancer stem cells. We identify key mediators and pathways in cancer stem cells whose response to PARP inhibition is not necessarily the same as the rest of the tumour cells. Since the cancer stem cells are known drivers of growth of tumours and their resistance to therapy, the clinical outcome might be drastically different than what is expected, if the effect of PARP inhibition on the cancer stem cells is not taken into account.

Comprehensive Analysis of microRNA Profiles in Organoids Derived from Human Colorectal Adenoma and Cancer

INTRODUCTION

Exosomes are membrane-enclosed nanovesicles, which are increasingly being recognized as important cell communication components for their role in transmitting microRNAs (miRNAs). No previous study has addressed the exosomal miRNA profile in colorectal adenomas (CRAs) because the long-term culture of CRA is challenging. This study aimed to identify the miRNA signature in organoid exosomes derived from human CRA and colorectal cancer (CRC) samples.

METHODS

Organoid cultures were developed from resected colorectal tissues of patients with CRA or CRC undergoing surgery or endoscopic mucosal resection. Exosomes were prepared from the conditioned medium of the organoids. miRNAs were prepared from the exosomes and their source organoids. The miRNA expression profiles were compared using microarray analysis. The impact of alteration of miRNA expression on cell proliferation was examined using miRNA mimics or inhibitors in HT-29 human CRC cells.

RESULTS

We established 6 organoid lines from CRC and 8 organoid lines from CRA. Exosomal miRNA signatures were different between the organoids derived from CRA and CRC. Both exosomal and cellular miR-1246 expressions were upregulated in CRC-derived organoids compared to their expression in CRA-derived organoids. Alteration of miR-1246 expression by the miR-1246 mimic or inhibitor increased or decreased cell proliferation in HT-29 cells, respectively.

CONCLUSIONS

We report for the first time the miRNA profiles of exosomes in CRA- and CRC-derived organoids. The upregulation of miR-1246 might play a role in increased cell proliferation in the process of CRA-carcinoma transition.

Targeting Notch to Maximize Chemotherapeutic Benefits: Rationale, Advanced Strategies, and Future Perspectives

Simple Summary

The Notch signaling pathway regulates cell proliferation, apoptosis, stem cell self-renewal, and differentiation in a context-dependent fashion both during embryonic development and in adult tissue homeostasis. Consistent with its pleiotropic physiological role, unproper activation of the signaling promotes or counteracts tumor pathogenesis and therapy response in distinct tissues. In the last twenty years, a wide number of studies have highlighted the anti-cancer potential of Notch-modulating agents as single treatment and in combination with the existent therapies. However, most of these strategies have failed in the clinical exploration due to dose-limiting toxicity and low efficacy, encouraging the development of novel agents and the design of more appropriate combinations between Notch signaling inhibitors and chemotherapeutic drugs with improved safety and effectiveness for distinct types of cancer.

Abstract

Notch signaling guides cell fate decisions by affecting proliferation, apoptosis, stem cell self-renewal, and differentiation depending on cell and tissue context. Given its multifaceted function during tissue development, both overactivation and loss of Notch signaling have been linked to tumorigenesis in ways that are either oncogenic or oncosuppressive, but always context-dependent. Notch signaling is critical for several mechanisms of chemoresistance including cancer stem cell maintenance, epithelial-mesenchymal transition, tumor-stroma interaction, and malignant neovascularization that makes its targeting an appealing strategy against tumor growth and recurrence. During the last decades, numerous Notch-interfering agents have been developed, and the abundant preclinical evidence has been transformed in orphan drug approval for few rare diseases. However, the majority of Notch-dependent malignancies remain untargeted, even if the application of Notch inhibitors alone or in combination with common chemotherapeutic drugs is being evaluated in clinical trials. The modest clinical success of current Notch-targeting strategies is mostly due to their limited efficacy and severe on-target toxicity in Notch-controlled healthy tissues. Here, we review the available preclinical and clinical evidence on combinatorial treatment between different Notch signaling inhibitors and existent chemotherapeutic drugs, providing a comprehensive picture of molecular mechanisms explaining the potential or lacking success of these combinations.

Wrinkle in the plan: miR-34a-5p impacts chemokine signaling by modulating CXCL10/CXCL11/CXCR3-axis in CD4+, CD8+ T cells, and M1 macrophages

BACKGROUND

In 2016 the first-in-human phase I study of a miRNA-based cancer therapy with a liposomal mimic of microRNA-34a-5p (miR-34a-5p) was closed due to five immune related serious adverse events (SAEs) resulting in four patient deaths. For future applications of miRNA mimics in cancer therapy it is mandatory to unravel the miRNA effects both on the tumor tissue and on immune cells. Here, we set out to analyze the impact of miR-34a-5p over-expression on the CXCL10/CXCL11/CXCR3 axis, which is central for the development of an effective cancer control.

METHODS

We performed a whole genome expression analysis of miR-34a-5p transfected M1 macrophages followed by an over-representation and a protein-protein network analysis. In-silico miRNA target prediction and dual luciferase assays were used for target identification and verification. Target genes involved in chemokine signaling were functionally analyzed in M1 macrophages, CD4⁺ and CD8⁺ T cells.

RESULTS

A whole genome expression analysis of M1 macrophages with induced miR-34a-5p over-expression revealed an interaction network of downregulated target mRNAs including CXCL10 and CXCL11. In-silico target prediction in combination with dual luciferase assays identified direct binding of miR-34a-5p to the 3'UTRs of CXCL10 and CXCL11. Decreased CXCL10 and CXCL11 secretion was shown on the endogenous protein level and in the supernatant of miR-34a-5p transfected and activated M1 macrophages. To complete the analysis of the CXCL10/CXCL11/CXCR3 axis, we activated miR-34a-5p transfected CD4⁺ and CD8⁺ T cells by PMA/Ionomycin and found reduced levels of endogenous CXCR3 and CXCR3 on the cell surface.

CONCLUSIONS

MiR-34a-5p mimic administered by intravenous administration will likely not only be up-taken by the tumor cells but also by the immune cells. Our results indicate that miR-34a-5p over-expression leads in M1 macrophages to a reduced secretion of CXCL10 and CXCL11 chemokines and in CD4⁺ and CD8⁺ T cells to a reduced expression of CXCR3. As a result, less immune cells will be attracted to the tumor site. Furthermore, high levels of miR-34a-5p in naive CD4⁺ T cells can in turn hinder Th1 cell polarization through the downregulation of CXCR3 leading to a less pronounced activation of cytotoxic T lymphocytes, natural killer, and natural killer T cells and possibly contributing to lymphocytopenia.

Biochemical Mechanisms Associating Alcohol Use Disorders with Cancers

Simple Summary

Of all yearly deaths attributable to alcohol consumption globally, approximately 12% are due to cancers, representing approximately 0.4 million deceased individuals. Ethanol metabolism disturbs cell biochemistry by targeting the structure and function of essential biomolecules (proteins, nucleic acids, and lipids) and by provoking alterations in cell programming that lead to cancer development and cancer malignancy. A better understanding of the metabolic and cell signaling realm affected by ethanol is paramount to designing effective treatments and preventive actions tailored to specific neoplasias.

Abstract

The World Health Organization identifies alcohol as a cause of several neoplasias of the oropharynx cavity, esophagus, gastrointestinal tract, larynx, liver, or female breast. We review ethanol’s nonoxidative and oxidative metabolism and one-carbon metabolism that encompasses both redox and transfer reactions that influence crucial cell proliferation machinery. Ethanol favors the uncontrolled production and action of free radicals, which interfere with the maintenance of essential cellular functions. We focus on the generation of protein, DNA, and lipid adducts that interfere with the cellular processes related to growth and differentiation. Ethanol’s effects on stem cells, which are responsible for building and repairing tissues, are reviewed. Cancer stem cells (CSCs) of different origins suffer disturbances related to the expression of cell surface markers, enzymes, and transcription factors after ethanol exposure with the consequent dysregulation of mechanisms related to cancer metastasis or resistance to treatments. Our analysis aims to underline and discuss potential targets that show more sensitivity to ethanol’s action and identify specific metabolic routes and metabolic realms that may be corrected to recover metabolic homeostasis after pharmacological intervention. Specifically, research should pay attention to re-establishing metabolic fluxes by fine-tuning the functioning of specific pathways related to one-carbon metabolism and antioxidant processes.

Partial EMT in Squamous Cell Carcinoma: A Snapshot

In the process of cancer EMT, some subgroups of cancer cells simultaneously exhibit both mesenchymal and epithelial characteristics, a phenomenon termed partial EMT (pEMT). pEMT is a plastic state in which cells coexpress epithelial and mesenchymal markers. In squamous cell carcinoma (SCC), pEMT is regulated, and the phenotype is maintained via the HIPPO pathway, NOTCH pathway and TGF-β pathways and by microRNAs, lncRNAs and the cancer microenvironment (CME); thus, SCC exhibits aggressive tumorigenic properties and high stemness, which leads collective migration and therapy resistance. Few studies have reported therapeutic interventions to address cells that have undergone pEMT, and this approach may be an effective way to inhibit the plasticity, drug resistance and metastatic potential of SCC.

The Promising Effect of Peucedanum chenur Chloroformic Extract on Prevention of Human Colorectal Cancer Progression by Modulating miR-135b, miR-21, and APC Genes

PURPOSE

The therapeutic use of herbal medicines for the diseases, including cancer, is increasing due to their lower side effects. The present research evaluated the effect of Peucedanum chenur chloroformic extract (PCCE) on cell proliferation against HCT-116 human colorectal cancer cell line.

METHODS

The cytotoxic effect of PCCE was evaluated by MTT assay. The activity of the Wnt/B-catenin pathway was assayed through measuring the expression of miR-135b, miR-21, and APC genes by real-time PCR. The flow cytometry and scratch tests were used to study the cell cycle and cell migration, respectively. Also, the antioxidant activity of PCCE was measured by DPPH and iron-chelating tests.

RESULTS

The results showed the downregulation of miR-135b and miR-21 and overexpression of the APC gene. Furthermore, PCCE decreased the free radicals, cell migration, and cell proliferation. The antioxidant activity of PCCE was confirmed by standard tests.

CONCLUSION

Altogether, our findings suggest that purified compounds of PCCE could be developed as a potent chemo-preventive drug for the treatment of CRC.

Stem Cell Theory of Cancer: Implications of a Viral Etiology in Certain Malignancies

Simple Summary

We postulate that a virus is more likely to cause cancer when it infects a progenitor stem-like cell rather than a progeny differentiated cell. We propose that the virus may turn out to be a surreptitious agent and a serendipitous model in our quest to investigate the origin of cancer. When it pertains, oncology recapitulates ontogeny, although genetic makeup is king. Cellular context may be the key to elucidating a stem cell origin of cancer.

Abstract

In 1911, Peyton Rous (Nobel Prize winner in 1966) demonstrated that a virus (i.e., RSV) caused cancer in chickens. In 1976, Bishop and Varmus (Nobel Prize winners in 1989) showed that the cellular origin of retroviral oncogenes was actually normal cellular genes (i.e., proto-oncogenes). In this article, we revisit the role viruses play in the genetic origin of cancer. We review a link between viruses or cancer and autoimmunity in an alternative stem cell origin of cancer. We propose that a virus is more likely to cause cancer when it infects a progenitor stem-like cell rather than a progeny differentiated cell. We postulate that both known (e.g., HBV and HPV) and novel viruses (e.g., SARS-CoV-2) pose an imminent threat in the emergence of chronic viral diseases as well as virally induced malignancies. Knowing the origin of cancer has profound implications on our current conception and perception of cancer. It affects our conduct in cancer research and our delivery of cancer care. It would be ironic if viruses turn out to be a useful tool and an ideal means in our quest to verify a genetic versus stem cell origin of cancer. When it pertains, oncology recapitulates ontogeny; although genetic makeup is pivotal, cellular context may be paramount to elucidating a stem cell origin of cancer.

High FRMD3 expression is prognostic for worse survival in rectal cancer patients treated with CCRT

BACKGROUND

Rectal cancer patients can conceivably obtain relief from neoadjuvant concurrent chemoradiotherapy (CCRT) for downstaging before resection, but the stratification of risk and clinical outcomes remains challenging. Therefore, identifying effective predictive biomarkers offers clinicians the opportunity to individually tailor early interventions, which would help optimize therapy.

METHODS

Using a public rectal cancer transcriptome dataset (GSE35452), we focused on cytoskeletal protein binding (GO: 0008092)-related genes and identified FERM domain containing 3 (FRMD3) as the most significant differentially expressed gene associated with CCRT resistance. We gathered 172 tumor samples from rectal cancer patients treated with neoadjuvant CCRT accompanied by curative resection and estimated the expression level of FRMD3 using immunohistochemistry.

RESULTS

The results revealed that high FRMD3 immunoexpression was remarkably associated with advanced pre-CCRT and post-CCRT tumor status (p = 0.004 and p < 0.001), pre-CCRT and post-CCRT lymph node metastasis (both p < 0.001), more perineurial invasion (p = 0.023), and a smaller extent of tumor regression (p = 0.018). High FRMD3 immunoexpression was remarkably correlated with inferior disease-specific survival (DSS) (p = 0.0001), local recurrence-free survival (LRFS) (p = 0.0003), and metastasis-free survival (MeFS) (p = 0.0023) at the univariate level. Furthermore, in multivariate analysis, high FRMD3 immunoexpression remained independently predictive of inferior DSS (p = 0.002), LRFS (p = 0.005), and MeFS (p = 0.015).

CONCLUSION

These results suggest that high FRMD3 expression is related to advanced clinicopathological features and inferior therapeutic responses in rectal cancer patients treated with CCRT, validating the promising prognostic value of FRMD3 expression.

High Yap and Mll1 promote a persistent regenerative cell state induced by Notch signaling and loss of p53

Specified intestinal epithelial cells reprogram and contribute to the regeneration and renewal of the epithelium upon injury. Mutations that deregulate such renewal processes may contribute to tumorigenesis. Using intestinal organoids, we show that concomitant activation of Notch signaling and ablation of p53 induce a highly proliferative and regenerative cell state, which is associated with increased levels of Yap and the histone methyltransferase Mll1. The induced signaling system orchestrates high proliferation, self-renewal, and niche-factor-independent growth, and elevates the trimethylation of histone 3 at lysine 4 (H3K4me3). We demonstrate that Yap and Mll1 are also elevated in patient-derived colorectal cancer (CRC) organoids and control growth and viability. Our data suggest that Notch activation and p53 ablation induce a signaling circuitry involving Yap and the epigenetic regulator Mll1, which locks cells in a proliferative and regenerative state that renders them susceptible for tumorigenesis.

Prion Protein of Extracellular Vesicle Regulates the Progression of Colorectal Cancer

Simple Summary

Cellular prion protein (PrP^C) are overexpressed in cancers and related to cancer proliferation, invasion, metastasis, and drug resistance. The aim of our study was to investigate the role of PrP^C-expressing exosomes regulating the colorectal cancer cells (CRC) behavior and tumor progression. We confirmed the increased sphere formation, expression of cancer initiating genes, motility, and tumor growth by hypoxic exosomes. Also, PrP^C-expressing exosomes induced the microenvironment of metastasis via increase of endothelial permeability and angiogenic cytokine secretion. The treatment of anti-PrP^C and 5-fluorouracil decreased the tumor progression. Targeting PrP^C is an effective therapeutic strategy in cancer therapy.

Abstract

Colorectal cancer (CRC) is one of the leading causes of cancer-related death due to its aggressive metastasis in later stages. Although there is a growing interest in the tumorigenic role of cellular prion protein (PrP^C) in the process of metastasis, the precise mechanism behind the cellular communication involving prion proteins remains poorly understood. This study found that hypoxic tumor microenvironment increased the PrP^C-expressing exosomes from CRC, and these exosomes regulate the CRC cell behavior and tumor progression depending on the expression of PrP^C. Hypoxic exosomes from CRC cells promoted sphere formation, the expression of tumor-inducing genes, migration, invasion, and tumor growth. Furthermore, these exosomes increased endothelial permeability, migration, invasion, and angiogenic cytokine secretion. These effects were associated with PrP^C expression. Application of anti-PrP^C antibody with 5-fluorouracil significantly suppressed the CRC progression in a murine xenograft model. Taken together, these findings indicate that PrP-expressing exosomes secreted by hypoxic CRC cells are a key factor in the tumorigenic CRC-to-CRC and CRC-to-endothelial cell communication. Significance: These findings suggest that inhibiting PrP^C in hypoxic exosomes during chemotherapy may be an effective therapeutic strategy in colorectal cancer.

The interaction between miRNAs/lncRNAs and Notch pathway in human disorders

Notch pathway is a signaling cascade with important impacts on cell proliferation, differentiation, developmental processes and tissue homeostasis. This pathway also regulates stem cell properties, thus being involved in both normal developmental processes and metastatic capacity of cancer cells. Lots of lncRNAs and miRNAs have been recognized that control Notch pathway at some levels or their expression is regulated by this pathway. FOXD2-AS1, MEG3, ANRIL, linc-OIP5, lincRNA-p21, CBR3-AS1, HOTAIR, PVT1 and GAS5 are among lncRNAs that interact with Notch signaling. miR-19, miR-21, miR-33a, miR-8/200, miR-34a, miR-146a, miR-37, miR-100, miR-107 and several other miRNAs have functional interplay with this signaling cascade. In the present review article, we have illuminated the interplay between lncRNAs/miRNAs and Notch pathway in two distinct contexts i.e. cancers and non-neoplastic conditions.

MicroRNA-34a: Potent Tumor Suppressor, Cancer Stem Cell Inhibitor, and Potential Anticancer Therapeutic

Overwhelming evidence indicates that virtually all treatment-naive tumors contain a subpopulation of cancer cells that possess some stem cell traits and properties and are operationally defined as cancer cell stem cells (CSCs). CSCs manifest inherent heterogeneity in that they may exist in an epithelial and proliferative state or a mesenchymal non-proliferative and invasive state. Spontaneous tumor progression, therapeutic treatments, and (epi)genetic mutations may also induce plasticity in non-CSCs and reprogram them into stem-like cancer cells. Intrinsic cancer cell heterogeneity and induced cancer cell plasticity, constantly and dynamically, generate a pool of CSC subpopulations with varying levels of epigenomic stability and stemness. Despite the dynamic and transient nature of CSCs, they play fundamental roles in mediating therapy resistance and tumor relapse. It is now clear that the stemness of CSCs is coordinately regulated by genetic factors and epigenetic mechanisms. Here, in this perspective, we first provide a brief updated overview of CSCs. We then focus on microRNA-34a (miR-34a), a tumor-suppressive microRNA (miRNA) devoid in many CSCs and advanced tumors. Being a member of the miR-34 family, miR-34a was identified as a p53 target in 2007. It is a bona fide tumor suppressor, and its expression is dysregulated and downregulated in various human cancers. By targeting stemness factors such as NOTCH, MYC, BCL-2, and CD44, miR-34a epigenetically and negatively regulates the functional properties of CSCs. We shall briefly discuss potential reasons behind the failure of the first-in-class clinical trial of MRX34, a liposomal miR-34a mimic. Finally, we offer several clinical settings where miR-34a can potentially be deployed to therapeutically target CSCs and advanced, therapy-resistant, and p53-mutant tumors in order to overcome therapy resistance and curb tumor relapse.

Unlocking the Secrets of Cancer Stem Cells with γ-Secretase Inhibitors: A Novel Anticancer Strategy

The dysregulation of Notch signaling is associated with a wide variety of different human cancers. Notch signaling activation mostly relies on the activity of the γ-secretase enzyme that cleaves the Notch receptors and releases the active intracellular domain. It is well-documented that γ-secretase inhibitors (GSIs) block the Notch activity, mainly by inhibiting the oncogenic activity of this pathway. To date, several GSIs have been introduced clinically for the treatment of various diseases, such as Alzheimer's disease and various cancers, and their impacts on Notch inhibition have been found to be promising. Therefore, GSIs are of great interest for cancer therapy. The objective of this review is to provide a systematic review of in vitro and in vivo studies for investigating the effect of GSIs on various cancer stem cells (CSCs), mainly by modulation of the Notch signaling pathway. Various scholarly electronic databases were searched and relevant studies published in the English language were collected up to February 2020. Herein, we conclude that GSIs can be potential candidates for CSC-targeting therapy. The outcome of our study also indicates that GSIs in combination with anticancer drugs have a greater inhibitory effect on CSCs.

A unique small cell lung carcinoma disease progression model shows progressive accumulation of cancer stem cell properties and CD44 as a potential diagnostic marker

OBJECTIVES

Cancer stem cells (CSCs) have been implicated in disease progression of aggressive cancers including small cell lung carcinoma (SCLC). Here, we have examined the possible contribution of CSCs to SCLC progression and aggressiveness.

MATERIALS AND METHODS

GLC-14, GLC-16 and GLC-19 SCLC cell lines derived from one patient, representing increasing progressive stages of disease were used. CSC marker expressions was determined by RT-qPCR and western blotting analyses, and heterogeneity was studied by CSC marker expression by immunofluorescence microscopy and flow cytometry. Colony formation assays were used to assess stem cell properties and therapy sensitivity.

RESULTS

Increasing expression of stem cell markers MYC, SOX2 and particularly CD44 were found in association with advancing disease. Single and overlapping expression of these markers indicated the presence of different CSC populations. The accumulation of more homogeneous double- and triple-positive CSC populations evolved with disease progression. Functional characterization of CSC properties affirmed higher proficiency of colony forming ability and increased resistance to γ-irradiation in GLC-16 and GLC-19 compared to GLC-14. GLC-19 colony formation was significantly inhibited by a human anti-CD44 antibody.

CONCLUSION

The progressive increase of MYC, SOX2 and particularly CD44 expression that was accompanied with enhanced colony forming capacity and resistance in the in vitro GLC disease progression model, supports the potential clinical relevance of CSC populations in malignancy and disease relapse of SCLC.

IL-6 and IL-8, secreted by myofibroblasts in the tumor microenvironment, activate HES1 to expand the cancer stem cell population in early colorectal tumor

Interaction between a tumor and its microenvironment is important for tumor initiation and progression. Cancer stem cells (CSCs) within the tumor interact with a microenvironmental niche that controls their maintenance and differentiation. We investigated the CSC-promoting effect of factors released from myofibroblasts into the microenvironment of early colorectal cancer tumors and its molecular mechanism. By messenger RNA microarray analysis, expression of HES1, a Notch signaling target, significantly increased in Caco-2 cells cocultured with 18Co cells (pericryptal myofibroblasts), compared to its expression in Caco-2 cells cultured alone. Caco-2 cells cultured in 18Co-conditioned media (CM) showed a significant increase in CD133+CD44+ cells and HES1 expression compared to that in Caco-2 cells cultured in regular media. Significant amounts of interleukin-6 (IL-6) and IL-8 were detected in 18Co-CM compared to levels in regular media. The 18Co-CM-induced increase in CD133+CD44+ cells was attenuated by IL-6- and IL-8-neutralizing antibodies. Furthermore, these neutralizing antibodies and inhibitors of STAT3 and gamma-secretase reduced the expression of HES1 induced in Caco-2 cells cultured in 18Co-CM. Immunohistochemical analysis of human tissues revealed that IL-6, IL-8, and HES1 expression increased from normal to adenoma, and from adenoma to cancer tissues. In addition, IL-6 and HES1 expression was positively correlated in early colorectal cancer tissues. In conclusion, the increase of CSCs by myofibroblasts could be mediated by IL-6/IL-8-induced HES1 activation in the tumor microenvironment. Based on these data, the IL-6/IL-8-mediated Notch/HES1 and STAT3 pathway, through which CSCs interact with their microenvironment, might be a potential target for the prevention and treatment of colorectal tumors.

Portrait of Cancer Stem Cells on Colorectal Cancer: Molecular Biomarkers, Signaling Pathways and miRNAome

Colorectal cancer (CRC) is a leading cause of cancer death worldwide, and about 20% is metastatic at diagnosis and untreatable. Increasing evidence suggests that the heterogeneous nature of CRC is related to colorectal cancer stem cells (CCSCs), a small cells population with stemness behaviors and responsible for tumor progression, recurrence, and therapy resistance. Growing knowledge of stem cells (SCs) biology has rapidly improved uncovering the molecular mechanisms and possible crosstalk/feedback loops between signaling pathways that directly influence intestinal homeostasis and tumorigenesis. The generation of CCSCs is probably connected to genetic changes in members of signaling pathways, which control self-renewal and pluripotency in SCs and then establish function and phenotype of CCSCs. Particularly, various deregulated CCSC-related miRNAs have been reported to modulate stemness features, controlling CCSCs functions such as regulation of cell cycle genes expression, epithelial-mesenchymal transition, metastasization, and drug-resistance mechanisms. Primarily, CCSC-related miRNAs work by regulating mainly signal pathways known to be involved in CCSCs biology. This review intends to summarize the epigenetic findings linked to miRNAome in the maintenance and regulation of CCSCs, including their relationships with different signaling pathways, which should help to identify specific diagnostic, prognostic, and predictive biomarkers for CRC, but also develop innovative CCSCs-targeted therapies.

Nanoceria, alone or in combination with cigarette-smoke condensate, induce transforming and epigenetic cancer-like features in vitro

Aim: To detect cell transformation effects of nanoceria after long-term exposure (up to 6 weeks) and to determine their potential interactions with cigarette smoke condensate, as a model of environmental carcinogenic pollutant. Materials & methods: Human bronchial epithelial BEAS-2 cells were used to determine transformation effects (invasion and tumorspheres induction), as well as changes in the expression of a battery of miRNAs related to the carcinogenesis process. Results: Nanoceria- and co-exposed cells exhibit cell transforming potential, with significantly increased invasion and tumorsphere formation abilities. Likewise, these exposures produced a high impact on the battery of miRNAs used. Conclusion: Nanoceria exposure induces cell-transformation and shows a positive interaction with the cell-transforming effects of cigarette smoke condensate. Besides, cerium dioxide nanoparticles and the co-exposure produced potential toxicity at the transcriptome level, which is related to tumorigenesis.

Regulation of Hedgehog Signaling by miRNAs and Nanoformulations: A Possible Therapeutic Solution for Colorectal Cancer

Hedgehog (Hh) signaling aberrations trigger differentiation and proliferation in colorectal cancer (CRC). However, the current approaches which inhibit this vital cellular pathway provoke some side effects. Therefore, it is necessary to look for new therapeutic options. MicroRNAs are small molecules that modulate expression of the target genes and can be utilized as a potential therapeutic option for CRC. On the other hand, nanoformulations have been implemented in the treatment of plethora of diseases. Owing to their excessive bioavailability, limited cytotoxicity and high specificity, nanoparticles may be considered as an alternative drug delivery platform for the Hh signaling mediated CRC. This article reviews the Hh signaling and its involvement in CRC with focus on miRNAs, nanoformulations as potential diagnostic/prognostic and therapeutics for CRC.

Non-coding RNAs and potential therapeutic targeting in cancer

Recent advances have begun to clarify the physiological and pathological roles of non-coding RNAs (ncRNAs) in various diseases, including cancer. Among these, microRNAs (miRNAs) have been the most studied and have emerged as key players that are involved in the regulation of important growth regulatory pathways in cancer pathogenesis. The ability of a single ncRNA to modulate the expression of multiple downstream gene targets and associated pathways, have provided a rationale to pursue them for therapeutic drug development in cancer. In this context, early data from pre-clinical studies have demonstrated that synthetic miRNA-based therapeutic molecules, along with various protective coating approaches, has allowed for their efficient delivery and anti-tumor activity. In fact, some of the miRNA-based cancer therapeutic strategies have shown promising results even in early-phase human clinical trials. While the enthusiasm for ncRNA-based cancer therapeutics continue to evolve, the field is still in the midst of unraveling a more precise understanding of the molecular mechanisms and specific downstream therapeutic targets of other lesser studied ncRNAs such as the long-non-coding RNAs, transfer RNAs, circular RNAs, small nucleolar RNAs, and piwi-interacting RNAs. This review article provides the current state of knowledge and the evolving principles for ncRNA-based therapeutic approaches in cancer, and specifically highlights the importance of data to date and the approaches that are being developed to overcome the challenges associated with their delivery and mitigating the off-target effects in human cancers.