IL-6 enriched lung cancer stem-like cell population by inhibition of cell cycle regulators via DNMT1 upregulation

Mitochondrial fission enhances IL-6-induced metastatic potential in ovarian cancer via ERK1/2 activation

Ovarian cancer is a lethal gynecologic cancer mostly diagnosed in an advanced stage with an accumulation of ascites. Interleukin-6 (IL-6), a pro-inflammatory cytokine is highly elevated in malignant ascites and plays a pleiotropic role in cancer progression. Mitochondria are dynamic organelles that undergo fission and fusion in response to external stimuli and dysregulation in their dynamics has been implicated in cancer progression and metastasis. Here, we investigate the effect of IL-6 on mitochondrial dynamics in ovarian cancer cells (OVCs) and its impact on metastatic potential. Treatment with IL-6 on ovarian cancer cell lines (SKOV3 and PA-1) led to an elevation in the metastatic potential of OVCs. Interestingly, a positive association was observed between dynamin-related protein 1 (Drp1), a regulator of mitochondrial fission, and IL-6R in metastatic ovarian cancer tissues. Additionally, IL-6 treatment on OVCs was linked to the activation of Drp1, with a notable increase in the ratio of the inhibitory form p-Drp1(S637) to the active form p-Drp1(S616), indicating enhanced mitochondrial fission. Moreover, IL-6 treatment triggered the activation of ERK1/2, and inhibiting ERK1/2 mitigated IL-6-induced mitochondrial fission. Suppressing mitochondrial fission through siRNA transfection and a pharmacological inhibitor reduced the IL-6-induced migration and invasion of OVCs. This was further supported by 3D invasion assays using patient-derived spheroids. Altogether, our study suggests the role of mitochondrial fission in the metastatic potential of OVCs induced by IL-6. The inhibition of mitochondrial fission could be a potential therapeutic approach to suppress the metastasis of ovarian cancer.

DNMT1/miR-152-3p/SOS1 signaling axis promotes self-renewal and tumor growth of cancer stem-like cells derived from non-small cell lung cancer

BACKGROUND

CSLCs(Cancer stem cell-like cells), which are central to tumorigenesis, are intrinsically influenced by epigenetic modifications. This study aimed to elucidate the underlying mechanism involving the DNMT1/miR-152-3p/SOS1 axis in regulating the self-renewal and tumor growth of LCSLCs (lung cancer stem-like cells).

MATERIALS AND METHODS

Target genes of miR-152-3p were predicted using TargetScan Human 8.0. Self-renewal and tumor growth of LCSLC were compared in suspension-cultured non-small cell lung cancer (NSCLC) cell lines H460 and A549 cell-derived globe cells. Functional effects of the DNMT1/miR-152-3p/SOS1 axis were assessed through gain-of-function experiments in vitro and in vivo. Additionally, luciferase reporter assays were employed to analyze the interaction among DNMT1, miR-152-3p, and SOS1.

RESULTS

Our findings highlight a negative interaction between DNMT1 and miR-152-3p, resulting in reduced miR-152-3p level. This, in turn, leads to the alleviation of the inhibitory effect of miR-152-3p on the target gene SOS1, ultimately activating SOS1 and playing an essential role in self-renewal and tumor growth of LCSLC. However, the alteration of SOS1 does not affect DNMT1/miR-152-3p regulation. Therefore, it is reasonable to infer that the DNMT1/miR-152-3p negative feedback loop critically sustains self-renewal and tumor growth of LCSLC through SOS1.

CONCLUSIONS

This study reveals a novel mechanism underpinning self-renewal and tumor growth of CSLC (cancer stem cell) in NSCLC and identifies potential therapeutic targets for NSCLC treatment.

The Nexus of Inflammation-Induced Epithelial-Mesenchymal Transition and Lung Cancer Progression: A Roadmap to Pentacyclic Triterpenoid-Based Therapies

Lung cancer is the leading cause of cancer-related death worldwide. Its high mortality is partly due to chronic inflammation that accompanies the disease and stimulates cancer progression. In this review, we analyzed recent studies and highlighted the role of the epithelial-mesenchymal transition (EMT) as a link between inflammation and lung cancer. In the inflammatory tumor microenvironment (iTME), fibroblasts, macrophages, granulocytes, and lymphocytes produce inflammatory mediators, some of which can induce EMT. This leads to increased invasiveness of tumor cells and self-renewal of cancer stem cells (CSCs), which are associated with metastasis and tumor recurrence, respectively. Based on published data, we propose that inflammation-induced EMT may be a potential therapeutic target for the treatment of lung cancer. This prospect is partially realized in the development of EMT inhibitors based on pentacyclic triterpenoids (PTs), described in the second part of our study. PTs reduce the metastatic potential and stemness of tumor cells, making PTs promising candidates for lung cancer therapy. We emphasize that the high diversity of molecular mechanisms underlying inflammation-induced EMT far exceeds those that have been implicated in drug development. Therefore, analysis of information on the relationship between the iTME and EMT is of great interest and may provide ideas for novel treatment approaches for lung cancer.

The use of non-steroid anti-inflammatory drugs during radical resection correlated with the outcome in non-small cell lung cancer

AIMS

The use of non-steroid anti-inflammatory drugs (NSAIDs) is conventional in management of postoperative pain in cancer patients, and further investigations have reported that some of these drugs correlated with the outcome in cancers. However, the prognostic value of the use of NSAIDs during surgery in non-small cell lung cancer (NSCLC) patients has been less addressed.

METHODS

NSCLC patients staged I-III are retrospectively enrolled, and the data of the use of NSAIDs during surgery are collected. Patients are divided into two subgroups according to the use intensity (UI) (low or high) of the NSAIDs, which was calculated by the accumulate dosage of all the NSAIDs divided by the length of hospitalization. The differences of the clinical features among these groups were checked. And the disease-free survival (DFS) and overall survival (OS) differences in these groups were compared by Kaplan-Meier analysis; risk factors for survival were validated by using a Cox proportional hazards model.

RESULTS

The UI was significant in predicting the DFS (AUC = 0.65, 95% CI: 0.57-0.73, P = 0.001) and OS (AUC = 0.70, 95% CI: 0.59-0.81, P = 0.001). Clinical features including type of resection (P = 0.001), N stages (P < 0.001), and TNM stages (P = 0.004) were significantly different in UI low (< 74.55 mg/day) or high (≥ 74.55 mg/day) subgroups. Patients in UI-high subgroups displayed significant superior DFS (log rank = 11.46, P = 0.001) and OS (log rank = 7.63, P = 0.006) than the UI-low ones. At last, the UI was found to be an independent risk factor for DFS (HR: 0.52, 95% CI: 0.28-0.95, P = 0.034).

CONCLUSIONS

The use of NSAIDs during radical resection in NSCLC patients correlated with the outcome and patients with a relative high UI has better outcome.

Casticin Attenuates Stemness in Cervical Cancer Stem-Like Cells by Regulating Activity and Expression of DNMT1

OBJECTIVE

To explore whether casticin (CAS) suppresses stemness in cancer stem-like cells (CSLCs) obtained from human cervical cancer (CCSLCs) and the underlying mechanism.

METHODS

Spheres from HeLa and CaSki cells were used as CCSLCs. DNA methyltransferase 1 (DNMT1) activity and mRNA levels, self-renewal capability (Nanog and Sox2), and cancer stem cell markers (CD133 and CD44), were detected by a colorimetric DNMT activity/inhibition assay kit, quantitative real-time reverse transcription-polymerase chain reaction, sphere and colony formation assays, and immunoblot, respectively. Knockdown and overexpression of DNMT1 by transfection with shRNA and cDNA, respectively, were performed to explore the mechanism for action of CAS (0, 10, 30, and 100 nmol/L).

RESULTS

DNMT1 activity was increased in CCSLCs compared with HeLa and CaSki cells (P<0.05). In addition, HeLa-derived CCSLCs transfected with DNMT1 shRNA showed reduced sphere and colony formation abilities, and lower CD133, CD44, Nanog and Sox2 protein expressions (P<0.05). Conversely, overexpression of DNMT1 in HeLa cells exhibited the oppositive effects. Furthermore, CAS significantly reduced DNMT1 activity and transcription levels as well as stemness in HeLa-derived CCSLCs (P<0.05). Interestingly, DNMT1 knockdown enhanced the inhibitory effect of CAS on stemness. As expected, DNMT1 overexpression reversed the inhibitory effect of CAS on stemness in HeLa cells.

CONCLUSION

CAS effectively inhibits stemness in CCSLCs through suppression of DNMT1 activation, suggesting that CAS acts as a promising preventive and therapeutic candidate in cervical cancer.

Deciphering Potential Role of Hippo Signaling Pathway in Breast Cancer: A Comprehensive Review

Breast cancer is a heterogeneous disease and a leading malignancy around the world. It is a vital cause of untimely mortality among women. Drug resistance is the major challenge for effective cancer therapeutics. In contrast, cancer stem cells (CSCs) are one of the reasons for drug resistance, tumor progression, and metastasis. The small population of CSCs present in each tumor has the ability of self-renewal, differentiation, and tumorigenicity. CSCs are often identified and enriched using a variety of cell surface markers (CD44, CD24, CD133, ABCG2, CD49f, LGR5, SSEA-3, CD70) that exert their functions by different regulatory networks, i.e., Notch, Wnt/β-catenin, hedgehog (Hh), and Hippo signaling pathways. Particularly the Hippo signaling pathway is the emerging and very less explored cancer stem cell pathway. Here, in this review, the Hippo signaling molecules are elaborated with respect to their ability of stemness as epigenetic modulators and how these molecules can be targeted for better cancer treatment and to overcome drug resistance.

Epigenetic regulation of stem cells in lung cancer oncogenesis and therapy resistance

Epigenetics plays an important role in regulating stem cell signaling, as well as in the oncogenesis of lung cancer and therapeutic resistance. Determining how to employ these regulatory mechanisms to treat cancer is an intriguing medical challenge. Lung cancer is caused by signals that cause aberrant differentiation of stem cells or progenitor cells. The different pathological subtypes of lung cancer are determined by the cells of origin. Additionally, emerging studies have demonstrated that the occurrence of cancer treatment resistance is connected to the hijacking of normal stem cell capability by lung cancer stem cells, especially in the processes of drug transport, DNA damage repair, and niche protection. In this review, we summarize the principles of the epigenetic regulation of stem cell signaling in relation to the emergence of lung cancer and resistance to therapy. Furthermore, several investigations have shown that the tumor immune microenvironment in lung cancer affects these regulatory pathways. And ongoing experiments on epigenetics-related therapeutic strategies provide new insight for the treatment of lung cancer in the future.

The role of IL-6/JAK2/STAT3 signaling pathway in cancers

Interleukin-6 (IL-6) is a pleiotropic cytokine involved in immune regulation. It can activate janus kinase 2 (JAK2)-signal transducer and activator of transcription 3 (STAT3) signaling pathway. As one of the important signal transduction pathways in cells, JAK2/STAT3 signaling pathway plays a critical role in cell proliferation and differentiation by affecting the activation state of downstream effector molecules. The activation of JAK2/STAT3 signaling pathway is involved in tumorigenesis and development. It contributes to the formation of tumor inflammatory microenvironment and is closely related to the occurrence and development of many human tumors. This article focuses on the relationship between IL-6/JAK2/STAT3 signaling pathway and liver cancer, breast cancer, colorectal cancer, gastric cancer, lung cancer, pancreatic cancer and ovarian cancer, hoping to provide references for the research of cancer treatment targeting key molecules in IL-6/JAK2/STAT3 signaling pathway.

Chronic inflammation, cancer development and immunotherapy

Chronic inflammation plays a pivotal role in cancer development. Cancer cells interact with adjacent cellular components (pro-inflammatory cells, intrinsic immune cells, stromal cells, etc.) and non-cellular components to form the inflammatory tumor microenvironment (TME). Interleukin 6 (IL-6), macrophage migration inhibitory factor (MIF), immune checkpoint factors and other pro-inflammatory cytokines produced by intrinsic immune cells in TME are the main mediators of intercellular communication in TME, which link chronic inflammation to cancer by stimulating different oncogenic signaling pathways and improving immune escape to promote cancer development. In parallel, the ability of monocytes, T regulatory cells (Tregs) and B regulatory cells (Bregs) to perform homeostatic tolerogenic functions is hijacked by cancer cells, leading to local or systemic immunosuppression. Standard treatments for advanced malignancies such as chemotherapy and radiotherapy have improved in the last decades. However, clinical outcomes of certain malignant cancers are not satisfactory due to drug resistance and side effects. The clinical application of immune checkpoint therapy (ICT) has brought hope to cancer treatment, although therapeutic efficacy are still limited due to the immunosuppressive microenvironment. Emerging evidences reveal that ideal therapies including clearance of tumor cells, disruption of tumor-induced immunosuppression by targeting suppressive TME as well as reactivation of anti-tumor T cells by ICT. Here, we review the impacts of the major pro-inflammatory cells, mediators and their downstream signaling molecules in TME on cancer development. We also discuss the application of targeting important components in the TME in the clinical management of cancer.

The metabolic addiction of cancer stem cells

Cancer stem cells (CSC) are the minor population of cancer originating cells that have the capacity of self-renewal, differentiation, and tumorigenicity (when transplanted into an immunocompromised animal). These low-copy number cell populations are believed to be resistant to conventional chemo and radiotherapy. It was reported that metabolic adaptation of these elusive cell populations is to a large extent responsible for their survival and distant metastasis. Warburg effect is a hallmark of most cancer in which the cancer cells prefer to metabolize glucose anaerobically, even under normoxic conditions. Warburg's aerobic glycolysis produces ATP efficiently promoting cell proliferation by reprogramming metabolism to increase glucose uptake and stimulating lactate production. This metabolic adaptation also seems to contribute to chemoresistance and immune evasion, a prerequisite for cancer cell survival and proliferation. Though we know a lot about metabolic fine-tuning in cancer, what is still in shadow is the identity of upstream regulators that orchestrates this process. Epigenetic modification of key metabolic enzymes seems to play a decisive role in this. By altering the metabolic flux, cancer cells polarize the biochemical reactions to selectively generate "onco-metabolites" that provide an added advantage for cell proliferation and survival. In this review, we explored the metabolic-epigenetic circuity in relation to cancer growth and proliferation and establish the fact how cancer cells may be addicted to specific metabolic pathways to meet their needs. Interestingly, even the immune system is re-calibrated to adapt to this altered scenario. Knowing the details is crucial for selective targeting of cancer stem cells by choking the rate-limiting stems and crucial branch points, preventing the formation of onco-metabolites.

Comprehensive Analysis of Ferroptosis- and Immune-Related Signatures to Improve the Prognosis and Diagnosis of Kidney Renal Clear Cell Carcinoma

Background

Almost 40% of patients with kidney renal clear cell carcinoma (KIRC) with advanced cancers eventually develop to metastases, and their 5-year survival rates are approximately 10%. Aberrant DNA methylations are significantly associated with the development of KIRC. The aim of our present study was to identify suitable ferroptosis- and immune-related (FI) biomarkers correlated with aberrant methylations to improve the prognosis and diagnosis of KIRC.

Methods

ChAMP and DESeq2 in R (3.6.2) were used to screen the differentially expressed methylation probes and differentially expressed genes, respectively. Univariate and multivariate Cox regression were used to identify the overall survival (OS)-related biomarkers.

Results

We finally identified five FI biomarkers (CCR4, CMTM3, IFITM1, MX2, and NR3C2) that were independently correlated with the OS of KIRC. The area under the curve value of the receiver operating characteristic value of prognosis model was 0.74, 0.68, and 0.72 in the training, validation, and entire cohorts, respectively. The sensitivity and specificity of the diagnosis model were 0.8698 and 0.9722, respectively. In addition, the prognosis model was also significantly correlated with several immune cells and factors.

Conclusion

Our present study suggested that these five FI-DEGs (CCR4, CMTM3, IFITM1, MX2, and NR3C2) could be used as prognosis and diagnosis biomarkers for patients with KIRC, but further cross-validation clinical studies are still needed to confirm them.

[Lung Cancer Stem-like Cells and Drug Resistance]

Lung cancer remains the leading cause of cancer-related death world-wide. Therapy resistance and relapse are considered major reasons contributing to the poor survival rates of lung cancer. Accumulated evidences have demonstrated that a small subpopulation of stem-like cells existed within lung cancer tissues and cell lines, possessing the abilities of self-renewal, multipotent differentiation and unlimited proliferation. These lung cancer stem-like cells (LCSCs) can generate tumors with high effeciency in vivo, survive cytotoxic therapies, and eventually lead to therapy resistance and recurrence. In this review, we would like to present recent knowledges on LCSCs, including the origins where they come from, the molecular features to identify them, and key mechanisms for them to survive and develop resistance, in order to provide a better view for targeting them in future clinic.
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Biomedical Applications of Non-Small Cell Lung Cancer Spheroids

Lung malignancies accounted for 11% of cancers worldwide in 2020 and remained the leading cause of cancer deaths. About 80% of lung cancers belong to non-small cell lung cancer (NSCLC), which is characterized by extremely high clonal and morphological heterogeneity of tumors and development of multidrug resistance. The improvement of current therapeutic strategies includes several directions. First, increasing knowledge in cancer biology results in better understanding of the mechanisms underlying malignant transformation, alterations in signal transduction, and crosstalk between cancer cells and the tumor microenvironment, including immune cells. In turn, it leads to the discovery of important molecular targets in cancer development, which might be affected pharmaceutically. The second direction focuses on the screening of novel drug candidates, synthetic or from natural sources. Finally, "personalization" of a therapeutic strategy enables maximal damage to the tumor of a patient. The personalization of treatment can be based on the drug screening performed using patient-derived tumor xenografts or in vitro patient-derived cell models. 3D multicellular cancer spheroids, generated from cancer cell lines or tumor-isolated cells, seem to be a helpful tool for the improvement of current NSCLC therapies. Spheroids are used as a tumor-mimicking in vitro model for screening of novel drugs, analysis of intercellular interactions, and oncogenic cell signaling. Moreover, several studies with tumor-derived spheroids suggest this model for the choice of "personalized" therapy. Here we aim to give an overview of the different applications of NSCLC spheroids and discuss the potential contribution of the spheroid model to the development of anticancer strategies.

Long noncoding RNA Meg3 sponges miR-708 to inhibit intestinal tumorigenesis via SOCS3-repressed cancer stem cells growth

BACKGROUND

Colorectal cancer (CRC) remains the most common gastrointestinal cancer and a leading cause of cancer deaths worldwide, with most showing pathologies indicating the malignant transformation of early stage intestinal stem cells. The long non-coding RNA Meg3, which functions as a tumor suppressor, has been reported to be abnormal in multiple tumorigenesis events; however, the underlying mechanism by which Meg3 contributes to the malignant proliferation of colonic stem cells remains unclear.

METHODS

We analyzed the expression levels of Meg3, miR-708, and SOCS3 in samples from Apc loss-of-function (Apc^min) mice and patients with CRC, particularly in colonic crypt cells. Apc^min mice and AMO/DSS-induced mice model (in vivo) and organoid culture system (in vitro) were used to explore the effect of the Meg3/miR-708/SOCS3 axis on tumorigenesis in the colon. In vitro, we performed RNApull-down, RNA immunoprecipitation, and luciferase reporter assays using DLD1 and RKO cell lines.

FINDINGS

The Meg3/miR-708/SOCS3 signaling axis plays a critical role in the early stage of CRC development. Our data showed Meg3 levels negatively correlate with miR-708 levels both in clinical samples and in the Apc^min mouse model, which indicated that Meg3 acts as a competitive endogenous RNA (ceRNA) of miR-708. Then, miR-708 served as an oncogene, inducing neoplasia in both Apc^min mice and cultured colonic organoids. Put together, miR-708 appears to promote malignant proliferation of colonic stem cells by targeting SOCS3/STAT3 signaling.

INTERPRETATION

These data revealed that Meg3 sponges miR-708 to inhibit CRC development via SOCS3-mediated repression of the malignant proliferation of colonic stem cells. The Meg3/miR-708/SOCS3 signaling axis provides potential targets for the diagnosis and treatment of CRC, particularly early stage CRC.

Epigenetic Signaling of Cancer Stem Cells During Inflammation

Malignant tumors pose a great challenge to human health, which has led to many studies increasingly elucidating the tumorigenic process. Cancer Stem Cells (CSCs) have profound impacts on tumorigenesis and development of drug resistance. Recently, there has been increased interest in the relationship between inflammation and CSCs but the mechanism underlying this relationship has not been fully elucidated. Inflammatory cytokines produced during chronic inflammation activate signaling pathways that regulate the generation of CSCs through epigenetic mechanisms. In this review, we focus on the effects of inflammation on cancer stem cells, particularly the role of signaling pathways such as NF-κB pathway, STAT3 pathway and Smad pathway involved in regulating epigenetic changes. We hope to provide a novel perspective for improving strategies for tumor treatment.

A Systematic Analysis Identifies Key Regulators Involved in Cell Proliferation and Potential Drugs for the Treatment of Human Lung Adenocarcinoma

Lung adenocarcinoma (LUAD) is one of the most common and malignant cancer types. Abnormal cell proliferation, exemplified by cell cycle and cell division dysregulation, is one of the most prominent hallmarks of cancer and is responsible for recurrence, metastasis, and resistance to cancer therapy. However, LUAD-specific gene regulation and clinical significance remain obscure. Here, by using both tissues and cells from LUAD and normal lung samples, 434 increased and 828 decreased genes of biological significance were detected, including 127 cell cycle-associated genes (95 increased and 32 decreased), 66 cell division-associated genes (56 increased and 10 decreased), and 81 cell proliferation-associated genes (34 increased and 47 decreased). Among them, 12 increased genes (TPX2, CENPF, BUB1, PLK1, KIF2C, AURKB, CDKN3, BUB1B, HMGA2, CDK1, ASPM, and CKS1B) and 2 decreased genes (TACC1 and MYH10) were associated with all the three above processes. Importantly, 2 (CDKN3 and CKS1B) out of the 11 increased genes (except HMGA2) are previously uncharacterized ones in LUAD and can potentially be prognostic markers. Moreover, PLK1 could be a promising therapeutic target for LUAD. Besides, protein–protein interaction network analysis showed that CDK1 and CDC20 were the hub genes, which might play crucial roles in cell proliferation of LUAD. Furthermore, transcriptional regulatory network analysis suggested that the transcription factor E2F1 could be a key regulator in controlling cell proliferation of LUAD via expression modulation of most cell cycle-, cell division-, and cell proliferation-related DEGs. Finally, trichostatin A, hycanthone, vorinostat, and mebeverine were identified as four potential therapeutic agents for LUAD. This work revealed key regulators contributing to cell proliferation in human LUAD and identified four potential therapeutic agents for treatment strategy.

miR-29b-3p Increases Radiosensitivity in Stemness Cancer Cells via Modulating Oncogenes Axis

Radioresistance conferred by cancer stem cells (CSCs) is the principal cause of the failure of cancer radiotherapy. Eradication of CSCs is a prime therapeutic target and a requirement for effective radiotherapy. Three dimensional (3D) cell-cultured model could mimic the morphology of cells in vivo and induce CSC properties. Emerging evidence suggests that microRNAs (miRNAs) play crucial roles in the regulation of radiosensitivity in cancers. In this study, we aim to investigate the effects of miRNAs on the radiosensitivity of 3D cultured stem-like cells. Using miRNA microarray analysis in 2D and 3D cell culture models, we found that the expression of miR-29b-3p was downregulated in 3D cultured A549 and MCF7 cells compared with monolayer (2D) cells. Clinic data analysis from The Cancer Genome Atlas database exhibited that miR-29b-3p high expression showed significant advantages in lung adenocarcinoma and breast invasive carcinoma patients’ prognosis. The subsequent experiments proved that miR-29b-3p overexpression decreased the radioresistance of cells in 3D culture and tumors in vivo through interfering kinetics process of DNA damage repair and inhibiting oncogenes RBL1, PIK3R1, AKT2, and Bcl-2. In addition, miR-29b-3p knockdown enhanced cancer cells invasion and migration capability. MiR-29b-3p overexpression decreased the stemness of 3D cultured cells. In conclusion, our results demonstrate that miR-29b-3p could be a sensitizer of radiation killing in CSC-like cells via inhibiting oncogenes expression. MiR-29b-3p could be a novel therapeutic candidate target for radiotherapy.

Novel Insights into Epigenetic Regulation of IL6 Pathway: In Silico Perspective on Inflammation and Cancer Relationship

IL-6 pathway is abnormally hyperactivated in several cancers triggering tumor cell growth and immune system inhibition. Along with genomic mutation, the IL6 pathway gene expression can be affected by DNA methylation, microRNAs, and post-translational modifications. Computational analysis was performed on the Cancer Genome Atlas (TCGA) datasets to explore the role of IL6, IL6R, IL6ST, and IL6R transmembrane isoform expression and their epigenetic regulation in different cancer types. IL6 was significantly modulated in 70% of tumor types, revealing either up- or down-regulation in an approximately equal number of tumors. Furthermore, IL6R and IL6ST were downregulated in more than 10 tumors. Interestingly, the correlation analysis demonstrated that only the IL6R expression was negatively affected by the DNA methylation within the promoter region in most tumors. Meanwhile, only the IL6ST expression was extensively modulated by miRNAs including miR-182-5p, which also directly targeted all three genes. In addition, IL6 upregulated miR-181a-3p, mirR-214-3p, miR-18a-5p, and miR-938, which in turn inhibited the expression of IL6 receptors. Finally, the patients’ survival rate was significantly affected by analyzed targets in some tumors. Our results suggest the relevance of epigenetic regulation of IL6 signaling and pave the way for further studies to validate these findings and to assess the prognostic and therapeutic predictive value of these epigenetic markers on the clinical outcome and survival of cancer patients.

Selectively targeting cancer stem cells: Current and novel therapeutic strategies and approaches in the effective eradication of cancer

Cancer stem cells (CSCs) are a subgroup of cells in malignant cancers, which possess self-renewal capacity, tumor-initiating capability, and pluripotency, as well as being responsible for tumor maintenance, metastasis, relapse, and chemoresistance. The treatment modalities previously established for cancer included surgery, chemotherapy, and radiotherapy. The majority of tumor cells of non-CSCs could be eradicated using conventional chemotherapy and radiotherapy. Therefore, novel and promising therapeutic strategies that selectively target CSCs are of great importance. In this review, we described different therapeutic strategies such as immunotherapy, metabolism-based therapeutic strategies, and additional potential therapeutic approaches (targeting microRNAs [miRNAs], histone deacetylase, and DNA methyl transferase) against CSCs. Taken together, due to the inefficiency of anticancer single therapies, targeting CSCs through their metabolism and using immunotherapy and miRNAs besides classical chemo- and radiotherapy may exert better therapeutic effects.

Epigenetic regulation of cancer stem cell formation and maintenance

Cancerous tumours contain a rare subset of cells with stem-like properties that are termed cancer stem cells (CSCs). CSCs are defined by their ability to divide both symmetrically and asymmetrically, to initiate new tumour growth and to tolerate the foreign niches required for metastatic dissemination. Accumulating evidence suggests that tumours arise from cells with stem-like properties, the generation of CSCs is therefore likely to be an initiatory event in carcinogenesis. Furthermore, CSCs in established tumours exist in a dynamic and plastic state, with nonstem tumour cells thought to be capable of de-differentiation to CSCs. The regulation of the CSC state both during tumour initiation and within established tumours is a desirable therapeutic target and is mediated by epigenetic factors. In this review, we will explore the epigenetic parallels between induced pluripotency and the generation of CSCs, and discuss how the epigenetic regulation of CSCs opens up novel opportunities for therapeutic intervention.

The stabilization of yes-associated protein by TGFβ-activated kinase 1 regulates the self-renewal and oncogenesis of gastric cancer stem cells

Gastric cancer (GC) is the most frequent digestive system malignant tumour and the second most common cause of cancer death globally. Cancer stem cell (CSC) is a small percentage of cancer cells in solid tumours that have differentiation, self‐renewal and tumorigenic capabilities. They have an active participation in the initiation, development, metastasis, recurrence and resistance of tumours to chemotherapy and radiotherapy. Gastric cancer stem cells (GCSCs) have been shown to be correlated with GC initiation and metastasis. In this study, we found that TAK1 expression level in GC tissues was significantly increased compared to the adjacent non‐cancerous tissues by RT‐qPCR, Western blot and immunohistochemistry. TAK1 has been identified as a critical molecule that promoted a variety of malignant GC phenotypes both in vivo and in vitro and promoted the self‐renewal of GCSCs. Mechanistically, TAK1 was up‐regulated by IL‐6 and prevented the degradation of yes‐associated protein (YAP) in the cytoplasm by binding to YAP. Thus, TAK1 promoted the SOX2 and SOX9 transcription and the self‐renewal and oncogenesis of GCSCs. Our findings provide insights into the mechanism of self‐renewal and tumorigenesis of TAK1 in GCSCs and have broad implications for clinical therapies.

Current understanding of epigenetics mechanism as a novel target in reducing cancer stem cells resistance

At present, after extensive studies in the field of cancer, cancer stem cells (CSCs) have been proposed as a major factor in tumor initiation, progression, metastasis, and recurrence. CSCs are a subpopulation of bulk tumors, with stem cell-like properties and tumorigenic capabilities, having the abilities of self-renewal and differentiation, thereby being able to generate heterogeneous lineages of cancer cells and lead to resistance toward anti-tumor treatments. Highly resistant to conventional chemo- and radiotherapy, CSCs have heterogeneity and can migrate to different organs and metastasize. Recent studies have demonstrated that the population of CSCs and the progression of cancer are increased by the deregulation of different epigenetic pathways having effects on gene expression patterns and key pathways connected with cell proliferation and survival. Further, epigenetic modifications (DNA methylation, histone modifications, and RNA methylations) have been revealed to be key drivers in the formation and maintenance of CSCs. Hence, identifying CSCs and targeting epigenetic pathways therein can offer new insights into the treatment of cancer. In the present review, recent studies are addressed in terms of the characteristics of CSCs, the resistance thereof, and the factors influencing the development thereof, with an emphasis on different types of epigenetic changes in genes and main signaling pathways involved therein. Finally, targeted therapy for CSCs by epigenetic drugs is referred to, which is a new approach in overcoming resistance and recurrence of cancer.

Expression of B7-H4 and IDO1 is associated with drug resistance and poor prognosis in high-grade serous ovarian carcinomas

High-grade serous ovarian carcinoma (HGSC) is the most lethal gynecologic malignancy. While immune checkpoint inhibitors against PD-L1 and CTLA-4 have shown significant effects in multiple tumor types, the response rate to single-agent immune checkpoint inhibitors is low in HGSC. Alternative biomarkers and targets must be identified to guide patient selection and new therapeutic strategies in HGSC. Here, we aim to investigate the clinical significance of novel immune modulators, including B7-H4, IDO1, Tim3, IL6, and IL-8, in patients with HGSC. A total of 48 patients with HGSCs, comprising 24 cases that were sensitive and 24 that were resistant to standard paclitaxel and carboplatin chemotherapy, were selected for our initial analysis. A NanoString assay including 33 immune-related genes was used to compare the expression of different immune regulatory molecules in the sensitive and resistant groups. Differentially expressed proteins were verified using multiplex immunohistochemical staining on tissue arrays of 202 patients with HGSCs who underwent primary surgery at MDACC. We analyzed the expression levels of immune checkpoints and compared expression profiles with clinicopathologic features including response, progression-free survival, and overall survival. HGSC tumors resistant to therapy expressed higher levels of B7-H4 (69.3%), IDO1 (71.8%), Tim3 (89.1%), and inflammatory factors IL-6 and IL-8, and expressed higher Tim3 in stromal components. High expression of B7-H4 and IDO1 was associated with significantly lower overall survival and progression-free survival. B7-H4 and IDO1 were co-expressed in 49.1% of studied cases. A panel of immunomodulatory proteins including B7-H4, IDO1, Tim3, IL-6, and IL-8 are expressed at high levels in HGSCs. These modulators represent novel targets to enhance immunotherapy in patients with HGSCs.

Immune evasion by cancer stem cells

Tumor immunity represents a new avenue for cancer therapy. Immune checkpoint inhibitors have successfully improved outcomes in several tumor types. In addition, currently, immune cell-based therapy is also attracting significant attention. However, the clinical efficacy of these treatments requires further improvement. The mechanisms through which cancer cells escape the immune response must be identified and clarified. Cancer stem cells (CSCs) play a central role in multiple aspects of malignant tumors. CSCs can initiate tumors in partially immunocompromised mice, whereas non-CSCs fail to form tumors, suggesting that tumor initiation is a definitive function of CSCs. However, the fact that non-CSCs also initiate tumors in more highly immunocompromised mice suggests that the immune evasion property may be a more fundamental feature of CSCs rather than a tumor-initiating property. In this review, we summarize studies that have elucidated how CSCs evade tumor immunity and create an immunosuppressive milieu with a focus on CSC-specific characteristics and functions. These profound mechanisms provide important clues for the development of novel tumor immunotherapies.

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Cancer stem cells (CSCs) play a central role in multiple aspects of malignant tumors.

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Immune evasion is a fundamental feature of CSCs.

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Immune evasion mechanisms must be precisely clarified to improve tumor immunotherapy.

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CSCs are promising targets for tumor immunotherapy.

Biophysical and epigenetic regulation of cancer stemness, invasiveness and immune action

PURPOSE OF REVIEW

The tumor microenvironment (TME) is an amalgam of multiple dysregulated biophysical cues that can alter cellular behavior through mechanotransductive signaling and epigenetic modifications. Through this review, we seek to characterize the extent of biophysical and epigenetic regulation of cancer stemness and tumor-associated immune cells in order to identify ideal targets for cancer therapy.

RECENT FINDINGS

Recent studies have identified cancer stemness and immune action as significant contributors to neoplastic disease, due to their susceptibility to microenvironmental influences. Matrix stiffening, altered vasculature, and resultant hypoxia within the TME can influence cancer stem cell (CSC) and immune cell behavior, as well as alter the epigenetic landscapes involved in cancer development.

SUMMARY

This review highlights the importance of aberrant biophysical cues in driving cancer progression through altered behavior of CSCs and immune cells, which in turn sustains further biophysical dysregulation. We examine current and potential therapeutic approaches that break this self-sustaining cycle of disease progression by targeting the presented biophysical and epigenetic signatures of cancer. We also summarize strategies including the normalization of the TME, targeted drug delivery, and inhibition of cancer-enabling epigenetic players.

Expression profiles and function of IL6 in polymorphonuclear myeloid-derived suppressor cells

IL6 is an inflammatory cytokine with pleiotropic functions in both immune and nonimmune cells, and its expression level is inversely correlated with disease prognosis in patients with cancer. However, blocking IL6 alone has only yielded minimal efficacy in human cancer patients. We aimed at defining IL6 expression profiles under inflammatory conditions and cancer, and elucidating the mechanism underlying IL6 intrinsic signaling in colon carcinoma. We report here that colonic inflammation induces IL6 expression primarily in the CD11b+Ly6G+Ly6Clo polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) in colon. Although both tumor cells, T cells and myeloid cells all express IL6, PMN-MDSCs are the primary cell type that express IL6 in colon carcinoma, suggesting that IL6 up-regulation is a response to inflammation in colon epithelium and tumor microenvironment. Furthermore, we determined that IL6 activates STAT3 to up-regulate DNMT1 and DNMT3b expression in colon tumor cells, thereby revealing an epigenetic mechanism that mediates the IL6-STAT3 signaling pathway in colon carcinoma. Surprisingly, knocking out IL6 in colon tumor cells did not significantly alter tumor growth in WT mice. Conversely, IL6-sufficient colon and pancreatic tumor grow at similar rate in WT and IL6-deficient mice. However, overexpression of IL6 in colon tumor cells significantly increases tumor growth in vivo. Our findings determine that a high tumor local IL6 threshold is essential for IL6 function in colon tumor promotion and targeting the IL6-expressing PMN-MDSCs is potentially an effective approach to suppress colon tumor growth in vivo.

Targeting Hypoxia Sensitizes TNBC to Cisplatin and Promotes Inhibition of Both Bulk and Cancer Stem Cells

Development of targeted therapies for triple-negative breast cancer (TNBC) is an unmet medical need. Cisplatin has demonstrated its promising potential for the treatment of TNBC in clinical trials; however, cisplatin treatment is associated with hypoxia that, in turn, promotes cancer stem cell (CSC) enrichment and drug resistance. Therapeutic approaches to attenuate this may lead to increased cisplatin efficacy in the clinic for the treatment of TNBC. In this report we analyzed clinical datasets of TNBC and found that TNBC patients possessed higher levels of EGFR and hypoxia gene expression. A similar expression pattern was also observed in cisplatin-resistant ovarian cancer cells. We, thus, developed a new therapeutic approach to inhibit EGFR and hypoxia by combination treatment with metformin and gefitinib that sensitized TNBC cells to cisplatin and led to the inhibition of both CD44+/CD24− and ALDH+ CSCs. We demonstrated a similar inhibition efficacy on organotypic cultures of TNBC patient samples ex vivo. Since these drugs have already been used frequently in the clinic; this study illustrates a novel, clinically translatable therapeutic approach to treat patients with TNBC.

LncRNA DLX6-AS1 Promotes Malignant Phenotype and Lymph Node Metastasis in Prostate Cancer by Inducing LARGE Methylation

Long non-coding RNAs (lncRNAs) have recently become recognized as crucial players in cancer cellular events including proliferation, migration, and invasion. Herein, we investigated the potential role of lncRNA DLX6-AS1 in prostate cancer cell malignant behaviors and lymph node metastasis. A differentially expressed lncRNA DLX6-AS1 and its downstream regulatory gene (LARGE) were predicted by analysis in silico. RT-qPCR and western blot analysis results demonstrated that DLX6-AS1 was highly expressed, but LARGE was poorly expressed in prostate cancer tissues and cells. The online website indicated that DLX6-AS1 negatively targeted LARGE expression, which was validated by Pearson correlation analysis and MSP. ChIP, RIP, and RNA pull-down assays further suggested that DLX6-AS1 downregulated LARGE expression through recruitment of DNMT1 to its promoter. We induced DLX6-AS1/LARGE overexpression or knockdown to examine their effects through Edu and Transwell assays, which revealed that DLX6-AS1 overexpression accelerated proliferation, invasion, and migration of prostate cancer cells, and that overexpression of LARGE rescued these effects. Tumors xenografts studies confirmed that DLX6-AS1 promoted lymph node metastasis by regulating LARGE, as evidenced by enhanced expression of MMP-9, uPAR, and cathepsin B. In summary, DLX6-AS1 stimulated prostate cancer malignant progression and lymph node metastasis by inducing DNMT1-mediated LARGE methylation, highlighting a potential therapeutic target against prostate cancer.

Autocrine IL6-Mediated Activation of the STAT3-DNMT Axis Silences the TNFα-RIP1 Necroptosis Pathway to Sustain Survival and Accumulation of Myeloid-Derived Suppressor Cells

Although accumulation of myeloid-derived suppressor cells (MDSC) is a hallmark of cancer, the underlying mechanism of this accumulation within the tumor microenvironment remains incompletely understood. We report here that TNFα-RIP1-mediated necroptosis regulates accumulation of MDSCs. In tumor-bearing mice, pharmacologic inhibition of DNMT with the DNA methyltransferease inhibitor decitabine (DAC) decreased MDSC accumulation and increased activation of antigen-specific cytotoxic T lymphocytes. DAC-induced decreases in MDSC accumulation correlated with increased expression of the myeloid cell lineage-specific transcription factor IRF8 in MDSCs. However, DAC also suppressed MDSC-like cell accumulation in IRF8-deficient mice, indicating that DNA methylation may regulate MDSC survival through an IRF8-independent mechanism. Instead, DAC decreased MDSC accumulation by increasing cell death via disrupting DNA methylation of RIP1-dependent targets of necroptosis. Genome-wide DNA bisulfite sequencing revealed that the Tnf promoter was hypermethylated in tumor-induced MDSCs in vivo. DAC treatment dramatically increased TNFα levels in MDSC in vitro, and neutralizing TNFα significantly increased MDSC accumulation and tumor growth in tumor-bearing mice in vivo. Recombinant TNFα induced MDSC cell death in a dose- and RIP1-dependent manner. IL6 was abundantly expressed in MDSCs in tumor-bearing mice and patients with human colorectal cancer. In vitro, IL6 treatment of MDSC-like cells activated STAT3, increased expression of DNMT1 and DNMT3b, and enhanced survival. Overall, our findings reveal that MDSCs establish a STAT3-DNMT epigenetic axis, regulated by autocrine IL6, to silence TNFα expression. This results in decreased TNFα-induced and RIP1-dependent necroptosis to sustain survival and accumulation. SIGNIFICANCE: These findings demonstrate that targeting IL6 expression or function represent potentially effective approaches to suppress MDSC survival and accumulation in the tumor microenvironment.

Anti-Proliferative Effect of Statins Is Mediated by DNMT1 Inhibition and p21 Expression in OSCC Cells

Statins, also known as HMG-CoA reductase inhibitors, are a class of cholesterol-lowering drugs and their anti-cancer effects have been studied in different types of malignant diseases. In the present study, we investigated the anti-proliferative effects of statins, including cerivastatin and simvastatin, on oral squamous cell carcinoma (OSCC) cells. Our data showed that statins inhibited the proliferation of three OSCC cell lines in a dose-dependent manner and this growth inhibition was confirmed through G₀/G₁ cell cycle arrest. Accordingly, we found the upregulation of p21 and downregulation of cyclin-dependent kinases, including CDK2, CDK4, and CDK6, in the statin-treated cells. Importantly, we clearly showed that statins were able to inhibit the expression of DNA methyltransferase 1 (DNMT1) and further promote the expression of p21. Taken together, our data demonstrated that the anti-proliferative effect of statins is mediated by suppressing DNMT1 expression, thus promoting p21 expression and leading to G₀/G₁ cell cycle arrest in OSCC cells.

A Comprehensive Network Pharmacology-Based Strategy to Investigate Multiple Mechanisms of HeChan Tablet on Lung Cancer

Background

HeChan tablet (HCT) is a traditional Chinese medicine preparation extensively prescribed to treat lung cancer in China. However, the pharmacological mechanisms of HCT on lung cancer remain to be elucidated.

Methods

A comprehensive network pharmacology-based strategy was conducted to explore underlying mechanisms of HCT on lung cancer. Putative targets and compounds of HCT were retrieved from TCMSP and BATMAN-TCM databases; related genes of lung cancer were retrieved from OMIM and DisGeNET databases; known therapeutic target genes of lung cancer were retrieved from TTD and DrugBank databases; PPI networks among target genes were constructed to filter hub genes by STRING. Furthermore, the pathway and GO enrichment analysis of hub genes was performed by clusterProfiler, and the clinical significance of hub genes was identified by The Cancer Genome Atlas.

Result

A total of 206 compounds and 2,433 target genes of HCT were obtained. 5,317 related genes of lung cancer and 77 known therapeutic target genes of lung cancer were identified. 507 unique target genes were identified among HCT-related genes of lung cancer and 34 unique target genes were identified among HCT-known therapeutic target genes of lung cancer. By PPI networks, 11 target genes AKT1, TP53, MAPK8, JUN, EGFR, TNF, INS, IL-6, MYC, VEGFA, and MAPK1 were identified as major hub genes. IL-6, JUN, EGFR, and MYC were shown to associate with the survival of lung cancer patients. Five compounds of HCT， quercetin, luteolin, kaempferol, beta-sitosterol, and baicalein were recognized as key compounds of HCT on lung cancer. The gene enrichment analysis implied that HCT probably benefitted patients with lung cancer by modulating the MAPK and PI3K-Akt pathways.

Conclusion

This study predicted pharmacological and molecular mechanisms of HCT against lung cancer and could pave the way for further experimental research and clinical application of HCT.

The screening role of a biomarker panel in BALF among patients with cancer-suspected pulmonary nodules less than 8 mm

BACKGROUND

It is intractable to differentiate the malignancy from benignancy of cancer-suspected pulmonary nodules less than 8 mm.

METHODS

The patients with small pulmonary nodules less than 8 mm which were suspected to be primary lung cancer underwent bronchoscopy and bronchoalveolar lavage. The level of vascular endothelial growth factor (VEGF), transforming growth factor-beta (TGF-β) and hepatocyte growth factor (HGF) in bronchoalveolar lavage fluid (BALF) were assayed. Then, all patients underwent histopathological examination by means of surgical resection of nodules to determine their benignancy or malignancy. The nodules' benignancy and malignancy suggested by the biomarker panel consisted of VEGF, TGF-β and HGF in BALF were validated by the histopathological results to determine their screening efficiency.

RESULTS

Among 405 patients with pulmonary nodules less than 8 mm, 252 and 153 were predicted to be malignant and benignant, respectively, by using the biomarker panel in BALF. Finally, 180 (71.4%) of 252 and 114 (74.5%) of 153 were validated to be truly malignant and benignant, respectively, according to the histopathological results. In a receiver operating characteristic curve analysis of screening efficiency for pulmonary nodules less than 8 mm, the results demonstrated that the AUC [0.807 (0.658-0.882)] of the biomarker panel in BALF was higher compared with that [0.605 (0.433-0.738)] of the biomarker panel in blood (P = .001).

CONCLUSIONS

For patients with cancer-suspected pulmonary nodules less 8 mm, a biomarker panel of VEGF, TGF-β and HGF in BALF demonstrated more eligible screening efficiency for the preliminary differentiation of malignancy from benignancy, by contrast with their level in blood as well as PET/CT.

DNMT1 as a therapeutic target in pancreatic cancer: mechanisms and clinical implications

BACKGROUND

Pancreatic cancer or pancreatic ductal adenocarcinoma (PDAC) is one of the most devastating cancer types with a 5-year survival rate of only 9%. PDAC is one of the leading causes of cancer-related deaths in both genders. Epigenetic alterations may lead to the suppression of tumor suppressor genes, and DNA methylation is a predominant epigenetic modification. DNA methyltransferase 1 (DNMT1) is required for maintaining patterns of DNA methylation during cellular replication. Accumulating evidence has implicated the oncogenic roles of DNMT1 in various malignancies including PDACs.

CONCLUSIONS

Herein, the expression profiles, oncogenic roles, regulators and inhibitors of DNMT1 in PDACs are presented and discussed. DNMT1 is overexpressed in PDAC cases compared with non-cancerous pancreatic ducts, and its expression gradually increases from pre-neoplastic lesions to PDACs. DNMT1 plays oncogenic roles in suppressing PDAC cell differentiation and in promoting their proliferation, migration and invasion, as well as in induction of the self-renewal capacity of PDAC cancer stem cells. These effects are achieved via promoter hypermethylation of tumor suppressor genes, including cyclin-dependent kinase inhibitors (e.g., p14, p15, p16, p21 and p27), suppressors of epithelial-mesenchymal transition (e.g., E-cadherin) and tumor suppressor miRNAs (e.g., miR-148a, miR-152 and miR-17-92 cluster). Pre-clinical investigations have shown the potency of novel non-nucleoside DNMT1 inhibitors against PDAC cells. Finally, phase I/II clinical trials of DNMT1 inhibitors (azacitidine, decitabine and guadecitabine) in PDAC patients are currently underway, where these inhibitors have the potential to sensitize PDACs to chemotherapy and immune checkpoint blockade therapy.

Lipid metabolism alteration contributes to and maintains the properties of cancer stem cells

Lipids, the basic components of the cell membrane, execute fundamental roles in almost all the cell activities including cell-cell recognition, signalling transduction and energy supplies. Lipid metabolism is elementary for life sustentation that balances activity between synthesis and degradation. An accumulating amount of data has indicated abnormal lipid metabolism in cancer stem cells (CSCs), and that the alteration of lipid metabolism exerts a great impact on CSCs' properties such as the capability of self-renewal, differentiation, invasion, metastasis, and drug sensitivity and resistance. CSCs' formation and maintenance cannot do without the regulation of fatty acids and cholesterol. In normal cells and embryonic development, fatty acids and cholesterol metabolism are regulated by some important signalling pathways (such as Hedgehog, Notch, Wnt signalling pathways); these signalling pathways also play crucial roles in initiating and/or maintaining CSCs' properties, and such signalling is shown to be commonly modulated by the abnormal lipid metabolism in CSCs; on the other hand, the altered lipid metabolism in turn modifies the cell signalling and generates additional impacts on CSCs. Metabolic rewiring is considered as an ideal hallmark of CSCs, and metabolic alterations would be promising therapeutic targets of CSCs for aggressive tumors. In this review, we summarize the most updated findings of lipid metabolic abnormalities in CSCs and prospect the potential applications of targeting lipid metabolism for anticancer treatment.

Senescence-Associated Pro-inflammatory Cytokines and Tumor Cell Plasticity

The well-recognized cell phenotypic heterogeneity in tumors is a great challenge for cancer treatment. Dynamic interconversion and movement within a spectrum of different cell phenotypes (cellular plasticity) with the acquisition of specific cell functions is a fascinating biological puzzle, that represent an additional difficulty for cancer treatment and novel therapies development. The understanding of the molecular mechanisms responsible for moving or stabilizing tumor cells within this spectrum of variable states constitutes a valuable tool to overcome these challenges. In particular, cell transitions between epithelial and mesenchymal phenotypes (EMT-MET) and de-and trans-differentiation processes are relevant, since it has been shown that they confer invasiveness, drug resistance, and metastatic ability, due to the simultaneous acquisition of stem-like cell properties. Multiple drivers participate in these cell conversions events. In particular, cellular senescence and senescence-associated soluble factors have been shown to unveil stem-like cell properties and cell plasticity. By modulating gradually the composition of their secretome and the time of exposure, senescent cells may have differential effect not only on tumor cells but also on surrounding cells. Intriguingly, tumor cells that scape from senescence acquire stem-like cell properties and aggressiveness. The reinforcement of senescence and inflammation by soluble factors and the participation of immune cells may provide a dynamic milieu having varied effects on cell transitions, reprogramming, plasticity, stemness and therefore heterogeneity. This will confer different epithelial/mesenchymal traits (hybrid phenotype) and stem-like cell properties, combinations of which, in a particular cell context, could be responsible for different cellular functions during cancer progression (survival, migration, invasion, colonization or proliferation). Additionally, cooperative behavior between cell subpopulations with different phenotypes/stemness functions could also modulate their cellular plasticity. Here, we will discuss the role of senescence and senescence-associated pro-inflammatory cytokines on the induction of cellular plasticity, their effect role in establishing particular states within this spectrum of cell phenotypes and how this is accompanied by stem-like cell properties that, as the epithelial transitions, may also have a continuum of characteristics providing tumor cells with functional adaptability specifically useful in the different stages of carcinogenesis.

Epigenetics in Inflammatory Breast Cancer: Biological Features and Therapeutic Perspectives

Evidence has emerged implicating epigenetic alterations in inflammatory breast cancer (IBC) origin and progression. IBC is a rare and rapidly progressing disease, considered the most aggressive type of breast cancer (BC). At clinical presentation, IBC is characterized by diffuse erythema, skin ridging, dermal lymphatic invasion, and peau d'orange aspect. The widespread distribution of the tumor as emboli throughout the breast and intra- and intertumor heterogeneity is associated with its poor prognosis. In this review, we highlighted studies documenting the essential roles of epigenetic mechanisms in remodeling chromatin and modulating gene expression during mammary gland differentiation and the development of IBC. Compiling evidence has emerged implicating epigenetic changes as a common denominator linking the main risk factors (socioeconomic status, environmental exposure to endocrine disruptors, racial disparities, and obesity) with IBC development. DNA methylation changes and their impact on the diagnosis, prognosis, and treatment of IBC are also described. Recent studies are focusing on the use of histone deacetylase inhibitors as promising epigenetic drugs for treating IBC. All efforts must be undertaken to unravel the epigenetic marks that drive this disease and how this knowledge could impact strategies to reduce the risk of IBC development and progression.

Radiation-Induced DNMT3B Promotes Radioresistance in Nasopharyngeal Carcinoma through Methylation of p53 and p21

Radiotherapy with or without concurrent chemotherapy is the standard treatment for nasopharyngeal carcinoma (NPC) patients, whose efficacy is limited partly by intrinsic and acquired radioresistance. DNA methyltransferase 3B (DNMT3B) has been reported to participate in tumorigenesis via DNA methylation, but its role in mediating progression and radioresistance of NPC remains unclear. Therefore, we conducted the following studies to explore the relationship between DNMT3B and NPC. Here, we found that DNMT3B was elevated in NPC tissues and predicted the poor prognosis of NPC patients. We demonstrated for the first time that ionizing radiation could induce DNMT3B, which might be one of the reasons for radioresistance. Silencing of DNMT3B inhibited migration and invasion via suppressing epithelial-mesenchymal transition (EMT) in NPC cells. Furthermore, silencing DNMT3B restored and activated p53 and p21 via DNA demethylation, which led to cell cycle arrest and apoptosis, resulting in increased radiosensitivity of NPC both in vitro and in vivo. DNMT3B functions as a novel oncogene in the radioresistance of NPC through regulating EMT, cell cycle, and apoptosis. Therefore, DNMT3B could be a potential target for NPC treatment.

The DNMT1/miR-34a/FOXM1 Axis Contributes to Stemness of Liver Cancer Cells

Background

Whether DNA methyltransferase 1 (DNMT1)/miR-34a/FoxM1 signaling promotes the stemness of liver cancer stem cells (LCSCs) remains unclear. This study aimed to assess whether methylation-based silencing of miR-34a by DNMT1 contributes to stemness features via FoxM1 upregulation in LCSCs.

Methods

The CD133⁺ subgroup of MHCC97H cells sorted by MACS was used as LCSCs. DNMT1, BMI1, SOX2, and OCT4 mRNA levels, and miR-34a amounts were determined by qRT-PCR. DNMT1, CD44, and FoxM1 proteins were analyzed by immunoblot. Sphere and colony formation abilities were detected by respective assays. CD133⁺ cell percentages were assessed by flow cytometry. In vivo oncogenicity was evaluated using a tumor xenograft model in mice. The effects of DNMT1/miR-34a signaling on the stemness of LCSCs were examined by knockdown or overexpression of DNMT1 and/or transfection of miR-34a mimic or inhibitor using lentivirus-delivery systems. FoxM1 association with miR-34a was detected by a reporter assay.

Results

We here showed that LCSCs exhibited elevated DNMT1 activity and expression, lower miR-34a expression with higher promoter methylation, and stronger stemness, compared with the parental liver cancer cells. DNMT1 knockdown repressed DNMT1, increased miR-34a amounts by promoter demethylation, and reduced stemness in LCSCs, whereas DNMT1 overexpression had the opposite effects in liver cancer cells. Transfection with miR-34a mimic repressed the stemness of LCSCs, while miR-34a inhibitor significantly downregulated miR-34a and enhanced stemness, without affecting DNMT1 in liver cancer cells. MiR-34a mimic rescued the effects of DNMT1 overexpression on the stemness of LCSCs, without affecting DNMT1 expression. Finally, FOXM1 was identified as a direct target by miR-34a in LCSCs.

Conclusions

We revealed that aberrant activation of DNMT1 causes miR-34a promoter methylation and suppression, leading to FoxM1 upregulation by disinhibition and promotion of LCSC stemness. These findings suggest that blockage of DNMT1/miR-34a-mediated FOXM1 upregulation might suppress liver cancer by targeting LCSCs.

Involvement of collagen XVII in pluripotency gene expression and metabolic reprogramming of lung cancer stem cells

BACKGROUND

Recent advancements in cancer biology field suggest that glucose metabolism is a potential target for cancer treatment. However, little if anything is known about the metabolic profile of cancer stem cells (CSCs) and the related underlying mechanisms.

METHODS

The metabolic phenotype in lung CSC was first investigated. The role of collagen XVII, a putative stem cell or CSC candidate marker, in regulating metabolic reprogramming in lung CSC was subsequently studied. Through screening the genes involved in glycolysis, we identified the downstream targets of collagen XVII that were involved in metabolic reprogramming of lung CSCs. Collagen XVII and its downstream targets were then used to predict the prognosis of lung cancer patients.

RESULTS

We showed that an aberrant upregulation of glycolysis and oxidative phosphorylation in lung CSCs is associated with the maintenance of CSC-like features, since blocking glycolysis and oxidative phosphorylation reduces sphere formation, chemoresistance, and tumorigenicity. We also showed that the Oct4-hexokinase 2 (HK2) pathway activated by collagen XVII-laminin-332 through FAK-PI3K/AKT-GSB3β/β-catenin activation induced the upregulation of glycolysis and maintenance of CSC-like features. Finally, we showed that collagen XVII, Oct4, and HK2 could be valuable markers to predict the prognosis of lung cancer patients.

CONCULSIONS

These data suggest the Oct4-HK2 pathway regulated by collagen XVII plays an important role in metabolic reprogramming and maintenance of CSC-like features in lung CSCs, which may aid in the development of new strategies in cancer treatment.

DNMT3b/OCT4 expression confers sorafenib resistance and poor prognosis of hepatocellular carcinoma through IL-6/STAT3 regulation

BACKGROUND

The inflammatory cytokine interleukin-6 (IL-6) is critical for the expression of octamer-binding transcription factor 4 (OCT4), which is highly associated with early tumor recurrence and poor prognosis of hepatocellular carcinomas (HCC). DNA methyltransferase (DNMT) family is closely linked with OCT4 expression and drug resistance. However, the underlying mechanism regarding the interplay between DNMTs and IL-6-induced OCT4 expression and the sorafenib resistance of HCC remains largely unclear.

METHODS

HCC tissue samples were used to examine the association between DNMTs/OCT4 expression levels and clinical prognosis. Serum levels of IL-6 were detected using ELISA assays (n = 144). Gain- and loss-of-function experiments were performed in cell lines and mouse xenograft models to determine the underlying mechanism in vitro and in vivo.

RESULTS

We demonstrate that levels of DNA methyltransferase 3 beta (DNMT3b) are significantly correlated with the OCT4 levels in HCC tissues (n = 144), and the OCT4 expression levels are positively associated with the serum IL-6 levels. Higher levels of IL-6, DNMT3b, or OCT4 predicted early HCC recurrence and poor prognosis. We show that IL-6/STAT3 activation increases DNMT3b/1 and OCT4 in HCC. Activated phospho-STAT3 (STAT-Y640F) significantly increased DNMT3b/OCT4, while dominant negative phospho-STAT3 (STAT-Y705F) was suppressive. Inhibiting DNMT3b with RNA interference or nanaomycin A (a selective DNMT3b inhibitor) effectively suppressed the IL-6 or STAT-Y640F-induced increase of DNMT3b-OCT4 and ALDH activity in vitro and in vivo. The fact that OCT4 regulates the DNMT1 expressions were further demonstrated either by OCT4 forced expression or DNMT1 silence. Additionally, the DNMT3b silencing reduced the OCT4 expression in sorafenib-resistant Hep3B cells with or without IL-6 treatment. Notably, targeting DNMT3b with nanaomycin A significantly increased the cell sensitivity to sorafenib, with a synergistic combination index (CI) in sorafenib-resistant Hep3B cells.

CONCLUSIONS

The DNMT3b plays a critical role in the IL-6-mediated OCT4 expression and the drug sensitivity of sorafenib-resistant HCC. The p-STAT3 activation increases the DNMT3b/OCT4 which confers the tumor early recurrence and poor prognosis of HCC patients. Findings from this study highlight the significance of IL-6-DNMT3b-mediated OCT4 expressions in future therapeutic target for patients expressing cancer stemness-related properties or sorafenib resistance in HCC.

Granulocyte Colony-stimulating Factor- and Interleukin-6-producing Large-cell Carcinoma of the Lung with Sarcomatoid Changes Suggestive of Epithelial-mesenchymal Transition: An Autopsy Case Report

A rare case of lung cancer with the simultaneous production of granulocyte colony-stimulating factor (G-CSF) and interleukin-6 (IL-6) is reported. A 79-year-old man was admitted to our hospital due to cachectic symptoms and an increased inflammatory response. Laboratory tests and imaging studies suggested metastatic lung cancer with high serum levels of G-CSF and IL-6. He died of progressive disease, and an autopsy showed that the lung tumor had positive protein expression of both cytokines and a solid growth of large-cell carcinoma with sarcomatoid changes, possibly resulting from the epithelial-mesenchymal transition mediated by IL-6 and leading to widespread metastases.

The DNMT1/miR-34a Axis Is Involved in the Stemness of Human Osteosarcoma Cells and Derived Stem-Like Cells

The DNA methyltransferase 1 (DNMT1)/miR-34a axis promoted carcinogenesis of various types of cancers. However, no literature reported its contribution to the stemness of osteosarcoma cancer stem-like cells (OSLCs). We sought to determine whether the DNMT1/miR-34a axis facilitates the stemness of OSLCs. We here revealed the higher DNMT1 activity and expression, lower miR-34a expression with high methylation of its promoter, and stronger stemness of OSLCs, as manifested by elevated sphere and colony formation capacities; CD133, CD44, ABCG2, Bmi1, Sox2, and Oct4 protein amounts in vitro; and carcinogenicity in a nude mouse xenograft model, when compared to the parental U2OS cells. 5-Azacytidine (Aza-dC) repressed DNMT1 activation and upregulated miR-34a expression by promoter demethylation and suppressed the stemness of OSLCs in a dose-dependent manner. DNMT1 knockdown increased miR-34a and reduced the stemness of OSLCs. Transfection with a miR-34a mimic repressed the stemness of OSLCs but did not alter DNMT1 activity and expression. Conversely, DNMT1 overexpression declined miR-34a levels, promoting the stemness of U2OS cells. Transfection with a miR-34a inhibitor enhanced the stemness of U2OS cells, without affecting the DNMT1 activity and expression. Importantly, reexpression of miR-34a could rescue the effects of DNMT1 overexpression on miR-34a inhibition as well as the stemness promotion without affecting the activity and expression of DNMT1. Our results revealed that aberrant activation of DNMT1 caused promoter methylation of miR-34a, leading to miR-34a underexpression, and the role of the DNMT1/miR-34a axis in promoting and sustaining the stemness of OSLCs.

Alterations in IL-6/STAT3 Signaling by Korean Mistletoe Lectin Regulate the Self-Renewal Activity of Placenta-Derived Mesenchymal Stem Cells

Korean mistletoe (Viscum album L. var. coloratum) lectin (VCA) is known as an anticancer drug. However, it is not clear whether VCA affects the self-renewal activity of mesenchymal stem cells (MSCs). Therefore, the objectives of this study were to analyze the effect of VCA on the proliferation of MSCs and expression of stemness markers. We also evaluated the usefulness of placenta-derived MSCs (PD-MSCs) as a screening tool. VCA was stably administered to MSCs, and analyzed self-renewal activities. The effect of IL-6 signaling on MSC proliferation was explored by quantitative methylation-specific PCR (qMSP) and western blot analysis. Compared with the control condition, low concentrations of VCA (10 pg/mL) induced an increase in the self-renewal activity of MSCs. Interestingly, a low concentration of VCA promoted IL-6 signaling in PD-MSCs through altered IL-6/STAT3 gene methylation. Furthermore, inhibition of IL-6 expression in PD-MSCs using an anti-IL-6 antibody caused a decrease in their self-renewal activity through IL-6/STAT3 signaling by altering IL-6/STAT3 gene methylation. These findings provide helpful data for understanding the mechanism of MSC self-renewal via VCA and show that VCA may be useful as a functional natural product for developing efficient therapies using placenta-derived stem cells.

Epigenetic Regulation of Inflammatory Cytokine-Induced Epithelial-To-Mesenchymal Cell Transition and Cancer Stem Cell Generation

The neoplastic transformation of normal to metastatic cancer cells is a complex multistep process involving the progressive accumulation of interacting genetic and epigenetic changes that alter gene function and affect cell physiology and homeostasis. Epigenetic changes including DNA methylation, histone modifications and changes in noncoding RNA expression, and deregulation of epigenetic processes can alter gene expression during the multistep process of carcinogenesis. Cancer progression and metastasis through an ‘invasion–metastasis cascade’ involving an epithelial-to-mesenchymal cell transition (EMT), the generation of cancer stem cells (CSCs), invasion of adjacent tissues, and dissemination are fueled by inflammation, which is considered a hallmark of cancer. Chronic inflammation is generated by inflammatory cytokines secreted by the tumor and the tumor-associated cells within the tumor microenvironment. Inflammatory cytokine signaling initiates signaling pathways leading to the activation of master transcription factors (TFs) such as Smads, STAT3, and NF-κB. Moreover, the same inflammatory responses also activate EMT-inducing TF (EMT-TF) families such as Snail, Twist, and Zeb, and epigenetic regulators including DNA and histone modifying enzymes and micoRNAs, through complex interconnected positive and negative feedback loops to regulate EMT and CSC generation. Here, we review the molecular regulatory feedback loops and networks involved in inflammatory cytokine-induced EMT and CSC generation.

Metal carcinogen exposure induces cancer stem cell-like property through epigenetic reprograming: A novel mechanism of metal carcinogenesis

Arsenic, cadmium, nickel and hexavalent chromium are among the most common environmental pollutants and potent carcinogens. Chronic exposure to these metals causes various types of cancer in humans, representing a significant environmental health issue. Although under active investigation, the mechanisms of metal carcinogenesis have not been clearly defined. One common feature of these metal carcinogens is that they are all able to cause various epigenetic dysregulations, which are believed to play important roles in their carcinogenicity. However, how metal carcinogen-caused epigenetic dysregulation contributes to metal carcinogenesis remains largely unknown. The evolution of cancer stem cell (CSC) theory has opened exciting new avenues for studying the mechanism of metal carcinogenesis. Increasing evidence indicates that chronic metal carcinogen exposure produces CSC-like cells through dysregulated epigenetic mechanisms. This review will first provide some brief introductions about CSC, epigenetics and epigenetic regulation of CSCs; then summarize progresses in recent studies on metal carcinogen-induced CSC-like property through epigenetic reprograming as a novel mechanism of metal carcinogenesis. Some perspectives for future studies in this field are also presented.

Sulforaphane Inhibits the Acquisition of Tobacco Smoke-Induced Lung Cancer Stem Cell-Like Properties via the IL-6/ΔNp63α/Notch Axis

Background: Tobacco smoke (TS) critically contributes to the development of lung cancer; however, the underlying molecular mechanisms remain unclear. The induction of cancer stem cells (CSCs) by TS represents an early event in tumor initiation. The lung cancer-related gene ΔNp63α is highly expressed in epithelial tissues and drives tumor formation and cancer stem cell properties. This study investigated the role of ΔNp63α in the long-term acquisition of TS-induced lung CSC-like properties. Methods: The expression levels of ΔNp63α, lung CSC markers, and interleukin (IL)-6 in lung carcinoma specimens were determined by western blotting and enzyme linked immunosorbent assays. Human bronchial epithelial (HBE) cells were chronically exposed to 2 % cigarette smoke extract for 55 passages, following which colony formation capacity, expression of proteins associated with malignant transformation, lung CSC markers, and tumor incidence were investigated. The effects of ΔNp63α on long-term TS exposure-induced lung CSC-like properties and Notch activation were analyzed using tumorsphere formation ability, immunofluorescence assays, luciferase reporter assays, and western blotting. The roles of IL-6 on chronic TS exposure-induced lung CSC-like properties and ΔNp63α expression were also examined. Moreover, the effects of sulforaphane (SFN) on TS-transformed lung CSC-like properties, IL-6 and ΔNp63α expression, and Notch signaling were investigated in vitro and in vivo. Results: Higher levels of ΔNp63α were observed in the lung cancer tissues of smokers than in those of non-smokers, whereas ΔNp63α was positively correlated with CD133 and Oct4 expression in lung cancer tissues. Data from the in vivo and in vitro experiments demonstrated that long-term TS exposure-transformed HBE (THBE) cells acquired lung CSC-like properties. Furthermore, ΔNp63α transcriptionally activated the Notch signaling pathway to promote the acquisition of CSC-like properties by the THBE cells. TS upregulated IL-6, which increased ΔNp63α expression in THBE sphere-forming cells. Finally, SFN inhibited the TS-induced CSC-like properties of THBE cells via the IL-6/ΔNp63α/Notch axis. Conclusion: Our data suggest that the IL-6/ΔNp63α/Notch axis plays an important role in the long-term TS exposure-induced acquisition of lung CSC-like properties and SFN intervention.

Key actors in cancer therapy: epigenetic modifiers

Epigenetic reprogramming plays a crucial role in the tumorigenicity and maintenance of tumor-specific gene expression that especially occurs through DNA methylation and/or histone modifications. It has well-defined mechanisms. It is known that alterations in the DNA methylation pattern and/or the loss of specific histone acetylation/methylation markers are related to several hallmarks of cancer, such as drug resistance, stemness, epithelial-mesenchymal transition, and metastasis. It has also recently been highlighted that epigenetic alterations are critical for the regulation of the stemlike properties of cancer cells (tumor-initiating cells; cancer stem cells). Cancer stem cells are thought to be responsible for the recurrence of cancer which makes the patient return to the clinic with metastatic tumor tissue. Hence, the dysregulation of epigenetic machinery represents potential new therapeutic targets. Therefore, compounds with epigenetic activities have become crucial for developing new therapy regimens (e.g., antimetastatic agents) in the fight against cancer. Here, we review the epigenetic modifiers that have already been used in the clinic and/or in clinical trials, related preclinical studies in cancer therapy, and the smart combination strategies that target cancer stem cells along with the other cancer cells. The emerging role of epitranscriptome (RNA epigenetic) in cancer therapy has also been included in this review as a new avenue and potential target for the better management of cancer-beneficial epigenetic machinery.

Interaction of estrogen receptor β5 and interleukin 6 receptor in the progression of non-small cell lung cancer

Numerous studies have shown that the estrogen receptor beta (ERβ) and interleukin 6 receptor (IL-6R) had interaction in many tumors, including lung cancer. Previous studies found that ERβ5 exhibits a different biological function compared with the other subtypes of ERβ. Therefore, this study mainly explores the interaction between ERβ5 and IL-6R in the progression of lung cancer. We found that the expression of ERβ5, IL-6 and glycoprotein 130 (GP130) were significantly increased (P < 0.001) and the 5-year survival rate with the co-expression of ERβ5 and GP130 is significantly lower (P = 0.0315) in non-small cell lung cancer (NSCLC) patients. The cell proliferation, invasion, and cell cycle were markedly increased, and the cell apoptotic was markedly inhibited with the concurrent action of ERβ5 and IL-6 in A549 cells (P < 0.05). In addition, the expression of ERβ5, GP130, p-AKT, and p-44/42 MAPK was also significantly increased in A549 cells (P < 0.05). These results indicate that ERβ5 and GP130 can synergistically promote the progression of NSCLC and maybe combined as an independent prognostic factor in patients. In addition, these results also provide a theoretical basis for the combined targeting therapy of ERβ5 and GP130 in NSCLC.