CTGF drives autophagy, glycolysis and senescence in cancer-associated fibroblasts via HIF1 activation, metabolically promoting tumor growth

Cellular senescence and metabolic reprogramming: Unraveling the intricate crosstalk in the immunosuppressive tumor microenvironment

The intrinsic oncogenic mechanisms and properties of the tumor microenvironment (TME) have been extensively investigated. Primary features of the TME include metabolic reprogramming, hypoxia, chronic inflammation, and tumor immunosuppression. Previous studies suggest that senescence-associated secretory phenotypes that mediate intercellular information exchange play a role in the dynamic evolution of the TME. Specifically, hypoxic adaptation, metabolic dysregulation, and phenotypic shifts in immune cells regulated by cellular senescence synergistically contribute to the development of an immunosuppressive microenvironment and chronic inflammation, thereby promoting the progression of tumor events. This review provides a comprehensive summary of the processes by which cellular senescence regulates the dynamic evolution of the tumor-adapted TME, with focus on the complex mechanisms underlying the relationship between senescence and changes in the biological functions of tumor cells. The available findings suggest that components of the TME collectively contribute to the progression of tumor events. The potential applications and challenges of targeted cellular senescence-based and combination therapies in clinical settings are further discussed within the context of advancing cellular senescence-related research.

Multifaceted TGF-β signaling, a master regulator: From bench-to-bedside, intricacies, and complexities

Physiological embryogenesis and adult tissue homeostasis are regulated by transforming growth factor-β (TGF-β), an evolutionarily conserved family of secreted polypeptide factors, acting in an autocrine and paracrine manner. The role of TGF-β in inflammation, fibrosis, and cancer is complex and sometimes even contradictory, exhibiting either inhibitory or promoting effects depending on the stage of the disease. Under pathological conditions, especially fibrosis and cancer, overexpressed TGF-β causes extracellular matrix deposition, epithelial-mesenchymal transition, cancer-associated fibroblast formation, and/or angiogenesis. In this review article, we have tried to dive deep into the mechanism of action of TGF-β in inflammation, fibrosis, and carcinogenesis. As TGF-β and its downstream signaling mechanism are implicated in fibrosis and carcinogenesis blocking this signaling mechanism appears to be a promising avenue. However, targeting TGF-β carries substantial risk as this pathway is implicated in multiple homeostatic processes and is also known to have tumor-suppressor functions. There is a need for careful dosing of TGF-β drugs for therapeutic use and patient selection.

Role of autophagy in cancer-associated fibroblast activation, signaling and metabolic reprograming

Tumors not only consist of cancerous cells, but they also harbor several normal-like cell types and non-cellular components. cancer-associated fibroblasts (CAFs) are one of these cellular components that are found predominantly in the tumor stroma. Autophagy is an intracellular degradation and quality control mechanism, and recent studies provided evidence that autophagy played a critical role in CAF formation, metabolic reprograming and tumor-stroma crosstalk. Therefore, shedding light on the autophagy and its role in CAF biology might help us better understand the roles of CAFs and the TME in cancer progression and may facilitate the exploitation of more efficient cancer diagnosis and treatment. Here, we provide an overview about the involvement of autophagy in CAF-related pathways, including transdifferentiation and activation of CAFs, and further discuss the implications of targeting tumor stroma as a treatment option.

The "Self-eating" of cancer-associated fibroblast: A potential target for cancer

Autophagy helps maintain energy homeostasis and protect cells from stress effects by selectively removing misfolded/polyubiquitylated proteins, lipids, and damaged mitochondria. Cancer-associated fibroblasts (CAFs) are cellular components of tumor microenvironment (TME). Autophagy in CAFs inhibits tumor development in the early stages; however, it has a tumor-promoting effect in advanced stages. In this review, we aimed to summarize the modulators responsible for the induction of autophagy in CAFs, such as hypoxia, nutrient deprivation, mitochondrial stress, and endoplasmic reticulum stress. In addition, we aimed to present autophagy-related signaling pathways in CAFs, and role of autophagy in CAF activation, tumor progression, tumor immune microenvironment. Autophagy in CAFs may be an emerging target for tumor therapy. In summary, autophagy in CAFs is regulated by a variety of modulators and can reshape tumor immune microenvironment, affecting tumor progression and treatment.

Towards dual function of autophagy in breast cancer: A potent regulator of tumor progression and therapy response

As a devastating disease, breast cancer has been responsible for decrease in life expectancy of females and its morbidity and mortality are high. Breast cancer is the most common tumor in females and its treatment has been based on employment of surgical resection, chemotherapy and radiotherapy. The changes in biological behavior of breast tumor relies on genomic and epigenetic mutations and depletions as well as dysregulation of molecular mechanisms that autophagy is among them. Autophagy function can be oncogenic in increasing tumorigenesis, and when it has pro-death function, it causes reduction in viability of tumor cells. The carcinogenic function of autophagy in breast tumor is an impediment towards effective therapy of patients, as it can cause drug resistance and radio-resistance. The important hallmarks of breast tumor such as glucose metabolism, proliferation, apoptosis and metastasis can be regulated by autophagy. Oncogenic autophagy can inhibit apoptosis, while it promotes stemness of breast tumor. Moreover, autophagy demonstrates interaction with tumor microenvironment components such as macrophages and its level can be regulated by anti-tumor compounds in breast tumor therapy. The reasons of considering autophagy in breast cancer therapy is its pleiotropic function, dual role (pro-survival and pro-death) and crosstalk with important molecular mechanisms such as apoptosis. Moreover, current review provides a pre-clinical and clinical evaluation of autophagy in breast tumor.

Pancreatic cancer and fibrosis: Targeting metabolic reprogramming and crosstalk of cancer-associated fibroblasts in the tumor microenvironment

Pancreatic cancer is one of the most dangerous types of cancer today, notable for its low survival rate and fibrosis. Deciphering the cellular composition and intercellular interactions in the tumor microenvironment (TME) is a necessary prerequisite to combat pancreatic cancer with precision. Cancer-associated fibroblasts (CAFs), as major producers of extracellular matrix (ECM), play a key role in tumor progression. CAFs display significant heterogeneity and perform different roles in tumor progression. Tumor cells turn CAFs into their slaves by inducing their metabolic dysregulation, exacerbating fibrosis to acquire drug resistance and immune evasion. This article reviews the impact of metabolic reprogramming, effect of obesity and cellular crosstalk of CAFs and tumor cells on fibrosis and describes relevant therapies targeting the metabolic reprogramming.

Cellular communication network 2 (connective tissue growth factor) aggravates acute DNA damage and subsequent DNA damage response-senescence-fibrosis following kidney ischemia reperfusion injury

Chronic allograft dysfunction with progressive fibrosis of unknown cause remains a major issue after kidney transplantation, characterized by ischemia-reperfusion injury (IRI). One hypothesis to account for this is that spontaneous progressive tubulointerstitial fibrosis following IRI is driven by cellular senescence evolving from a prolonged, unresolved DNA damage response (DDR). Since cellular communication network factor 2 ((CCN2), formerly called connective tissue growth factor), an established mediator of kidney fibrosis, is also involved in senescence-associated pathways, we investigated the relation between CCN2 and cellular senescence following kidney transplantation. Tubular CCN2 overexpression was found to be associated with DDR, loss of kidney function and tubulointerstitial fibrosis in both the early and the late phase in human kidney allograft biopsies. Consistently, CCN2 deficient mice developed reduced senescence and tubulointerstitial fibrosis in the late phase; six weeks after experimental IRI. Moreover, tubular DDR markers and plasma urea were less elevated in CCN2 knockout than in wild-type mice. Finally, CCN2 administration or overexpression in epithelial cells induced upregulation of tubular senescence-associated genes including p21, while silencing of CCN2 alleviated DDR induced by anoxia-reoxygenation injury in cultured proximal tubule epithelial cells. Thus, our observations indicate that inhibition of CCN2 can mitigate IRI-induced acute kidney injury, DNA damage, and the subsequent DDR-senescence-fibrosis sequence. Hence, targeting CCN2 might help to protect the kidney from transplantation-associated post-IRI chronic kidney dysfunction.

Emerging role of microtubule-associated proteins on cancer metastasis

The major cause of death in cancer patients is strongly associated with metastasis. While much remains to be understood, microtubule-associated proteins (MAPs) have shed light on metastatic progression’s molecular mechanisms. In this review article, we focus on the role of MAPs in cancer aggressiveness, particularly cancer metastasis activity. Increasing evidence has shown that a growing number of MAP member proteins might be fundamental regulators involved in altering microtubule dynamics, contributing to cancer migration, invasion, and epithelial-to-mesenchymal transition. MAP types have been established according to their microtubule-binding site and function in microtubule-dependent activities. We highlight that altered MAP expression was commonly found in many cancer types and related to cancer progression based on available evidence. Furthermore, we discuss and integrate the relevance of MAPs and related molecular signaling pathways in cancer metastasis. Our review provides a comprehensive understanding of MAP function on microtubules. It elucidates how MAPs regulate cancer progression, preferentially in metastasis, providing substantial scientific information on MAPs as potential therapeutic targets and prognostic markers for cancer management.

Metabolic reprogramming and crosstalk of cancer-related fibroblasts and immune cells in the tumor microenvironment

It is notorious that cancer cells alter their metabolism to adjust to harsh environments of hypoxia and nutritional starvation. Metabolic reprogramming most often occurs in the tumor microenvironment (TME). TME is defined as the cellular environment in which the tumor resides. This includes surrounding blood vessels, fibroblasts, immune cells, signaling molecules and the extracellular matrix (ECM). It is increasingly recognized that cancer cells, fibroblasts and immune cells within TME can regulate tumor progression through metabolic reprogramming. As the most significant proportion of cells among all the stromal cells that constitute TME, cancer-associated fibroblasts (CAFs) are closely associated with tumorigenesis and progression. Multitudinous studies have shown that CAFs participate in and promote tumor metabolic reprogramming and exert regulatory effects via the dysregulation of metabolic pathways. Previous studies have demonstrated that curbing the substance exchange between CAFs and tumor cells can dramatically restrain tumor growth. Emerging studies suggest that CAFs within the TME have emerged as important determinants of metabolic reprogramming. Metabolic reprogramming also occurs in the metabolic pattern of immune cells. In the meanwhile, immune cell phenotype and functions are metabolically regulated. Notably, immune cell functions influenced by metabolic programs may ultimately lead to alterations in tumor immunity. Despite the fact that multiple previous researches have been devoted to studying the interplays between different cells in the tumor microenvironment, the complicated relationship between CAFs and immune cells and implications of metabolic reprogramming remains unknown and requires further investigation. In this review, we discuss our current comprehension of metabolic reprogramming of CAFs and immune cells (mainly glucose, amino acid, and lipid metabolism) and crosstalk between them that induces immune responses, and we also highlight their contributions to tumorigenesis and progression. Furthermore, we underscore potential therapeutic opportunities arising from metabolism dysregulation and metabolic crosstalk, focusing on strategies targeting CAFs and immune cell metabolic crosstalk in cancer immunotherapy.

Cancer-Associated Fibroblasts in the Hypoxic Tumor Microenvironment

Simple Summary

Cancers have regions of low oxygen concentration where hypoxia-related signaling pathways are activated. The hypoxic tumor microenvironment has been widely accepted as a hallmark of cancer and shown to be a critical factor in the crosstalk between cancer and stromal cells. Fibroblasts are one of the most abundant cellular components in the tumor stroma and are also significantly affected by oxygen deprivation. In this case, we discuss the molecular and cellular mechanisms that regulate fibroblasts under hypoxic conditions and their effect on cancer development and progression. Unraveling these regulatory mechanisms could be exploited in developing potential fibroblast-specific therapeutics for cancer.

Abstract

Solid cancers are composed of malignant cells and their surrounding matrix components. Hypoxia plays a critical role in shaping the tumor microenvironment that contributes to cancer progression and treatment failure. Cancer-associated fibroblasts (CAFs) are one of the most prominent components of the tumor microenvironment. CAFs are highly sensitive to hypoxia and participates in the crosstalk with cancer cells. Hypoxic CAFs modulate several mechanisms that induce cancer malignancy, such as extracellular matrix (ECM) remodeling, immune evasion, metabolic reprogramming, angiogenesis, metastasis, and drug resistance. Key signaling molecules regulating CAFs in hypoxia include transforming growth factor (TGF-β) and hypoxia-inducible factors (HIFs). In this article, we summarize the mechanisms underlying the hypoxic regulation of CAFs and how hypoxic CAFs affect cancer development and progression. We also discuss the potential therapeutic strategies focused on targeting CAFs in the hypoxic tumor microenvironment.

Connective Tissue Growth Factor in Idiopathic Pulmonary Fibrosis: Breaking the Bridge

CTGF is upregulated in patients with idiopathic pulmonary fibrosis (IPF), characterized by the deposition of a pathological extracellular matrix (ECM). Additionally, many omics studies confirmed that aberrant cellular senescence-associated mitochondria dysfunction and metabolic reprogramming had been identified in different IPF lung cells (alveolar epithelial cells, alveolar endothelial cells, fibroblasts, and macrophages). Here, we reviewed the role of the CTGF in IPF lung cells to mediate anomalous senescence-related metabolic mechanisms that support the fibrotic environment in IPF.

Biliary Epithelial Senescence in Liver Disease: There Will Be SASP

Cellular senescence is a pathophysiological phenomenon in which proliferative cells enter cell cycle arrest following DNA damage and other stress signals. Natural, permanent DNA damage can occur after repetitive cell division; however, acute stress or other injuries can push cells into premature senescence and eventually a senescence-associated secretory phenotype (SASP). In recent years, there has been increased evidence for the role of premature senescence in disease progression including diabetes, cardiac diseases, and end-stage liver diseases including cholestasis. Liver size and function change with aging, and presumably with increasing cellular senescence, so it is important to understand the mechanisms by which cellular senescence affects the functional nature of the liver in health and disease. As well, cells in a SASP state secrete a multitude of inflammatory and pro-fibrogenic factors that modulate the microenvironment. Cellular SASP and the associated, secreted factors have been implicated in the progression of liver diseases, such as cholestatic injury that target the biliary epithelial cells (i.e., cholangiocytes) lining the bile ducts. Indeed, cholangiocyte senescence/SASP is proposed to be a driver of disease phenotypes in a variety of liver injuries. Within this review, we will discuss the impact of cholangiocyte senescence and SASP in the pathogenesis of cholestatic disorders.

Autophagy and ncRNAs: Dangerous Liaisons in the Crosstalk between the Tumor and Its Microenvironment

Simple Summary

Tumor cells communicate with the stromal cells within the tumor microenvironment (TME) to create a conducive environment for tumor growth. One major avenue for mediating crosstalk between various cell types in the TME involves exchanges of molecular payloads in the form of extracellular vesicles/exosomes. Autophagy is a fundamental mechanism to maintain intracellular homeostasis but recent reports suggest that secretory autophagy plays an important role in promoting secretion of exosomes that are packaged with non-coding RNAs (ncRNAs) and other biomolecules from the donor cell. Uptake of exosomal autophagy-modulating ncRNAs by recipient cells may further perpetuate tumor progression.

Abstract

Autophagy is a fundamental cellular homeostasis mechanism known to play multifaceted roles in the natural history of cancers over time. It has recently been shown that autophagy also mediates the crosstalk between the tumor and its microenvironment by promoting the export of molecular payloads such as non-coding RNA (ncRNAs) via LC3-dependent Extracellular Vesicle loading and secretion (LDELS). In turn, the dynamic exchange of exosomal ncRNAs regulate autophagic responses in the recipient cells within the tumor microenvironment (TME), for both tumor and stromal cells. Autophagy-dependent phenotypic changes in the recipient cells further enhance tumor growth and metastasis, through diverse biological processes, including nutrient supplementation, immune evasion, angiogenesis, and therapeutic resistance. In this review, we discuss how the feedforward autophagy-ncRNA axis orchestrates vital communications between various cell types within the TME ecosystem to promote cancer progression.

CCN2 Aggravates the Immediate Oxidative Stress-DNA Damage Response following Renal Ischemia-Reperfusion Injury

AKI, due to the fact of altered oxygen supply after kidney transplantation, is characterized by renal ischemia–reperfusion injury (IRI). Recent data suggest that AKI to CKD progression may be driven by cellular senescence evolving from prolonged DNA damage response (DDR) following oxidative stress. Cellular communication factor 2 (CCN2, formerly called CTGF) is a major contributor to CKD development and was found to aggravate DNA damage and the subsequent DDR–cellular senescence–fibrosis sequence following renal IRI. We therefore investigated the impact of CCN2 inhibition on oxidative stress and DDR in vivo and in vitro. Four hours after reperfusion, full transcriptome RNA sequencing of mouse IRI kidneys revealed CCN2-dependent enrichment of several signaling pathways, reflecting a different immediate stress response to IRI. Furthermore, decreased staining for γH2AX and p-p53 indicated reduced DNA damage and DDR in tubular epithelial cells of CCN2 knockout (KO) mice. Three days after IRI, DNA damage and DDR were still reduced in CCN2 KO, and this was associated with reduced oxidative stress, marked by lower lipid peroxidation, protein nitrosylation, and kidney expression levels of Nrf2 target genes (i.e., HMOX1 and NQO1). Finally, silencing of CCN2 alleviated DDR and lipid peroxidation induced by anoxia-reoxygenation injury in cultured PTECs. Together, our observations suggest that CCN2 inhibition might mitigate AKI by reducing oxidative stress-induced DNA damage and the subsequent DDR. Thus, targeting CCN2 might help to limit post-IRI AKI.

Arl4c promotes the growth and drug resistance of pancreatic cancer by regulating tumor-stromal interactions

Emerging evidence suggests that ADP-ribosylation factor like-4c (Arl4c) may be a potential choice for cancer treatment. However, its role in pancreatic cancer, especially in tumor-stroma interactions and drug resistance, is still unknown. In the current study, we examined the proliferation and drug resistance effect of Arl4c on pancreatic cancer cells. Furthermore, we explored the contribution of Arl4c high expression in pancreatic stellate cell (PSC) activation. We found that high Arl4c expression is associated with cell proliferation, drug resistance, and PSC activation. In detail, Arl4c regulates connective tissue growth factor (CTGF) paracrine, further induces autophagic flux in PSCs, resulting in PSC activation. TGFβ1 secreted by activated PSCs enhances cancer cell stem cell properties via smad2 signaling, further increasing cell drug resistance. YAP is an important mediator of the Arl4c-CTGF loop. Taken together, these results suggest that Arl4c is essential for pancreatic cancer progression and may be an effective therapeutic choice.

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High Arl4c expression is correlated with PSCs activation and drug resistance

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Yap-CTGF-mediated autophagy is required for Arl4c-related PSCs activation

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Paracrine TGFβ1 of PSCs plays pivotal role in drug resistance of pancreatic cancer cells

Unfolding the role of autophagy in the cancer metabolism

Autophagy is considered an indispensable process that scavenges toxins, recycles complex macromolecules, and sustains the essential cellular functions. In addition to its housekeeping role, autophagy plays a substantial role in many pathophysiological processes such as cancer. Certainly, it adapts cancer cells to thrive in the stress conditions such as hypoxia and starvation. Cancer cells indeed have also evolved by exploiting the autophagy process to fulfill energy requirements through the production of metabolic fuel sources and fundamentally altered metabolic pathways. Occasionally autophagy as a foe impedes tumorigenesis and promotes cell death. The complex role of autophagy in cancer makes it a potent therapeutic target and has been actively tested in clinical trials. Moreover, the versatility of autophagy has opened new avenues of effective combinatorial therapeutic strategies. Thereby, it is imperative to comprehend the specificity of autophagy in cancer-metabolism. This review summarizes the recent research and conceptual framework on the regulation of autophagy by various metabolic pathways, enzymes, and their cross-talk in the cancer milieu, including the implementation of altered metabolism and autophagy in clinically approved and experimental therapeutics.

Atractylenolide-I Sensitizes Triple-Negative Breast Cancer Cells to Paclitaxel by Blocking CTGF Expression and Fibroblast Activation

This investigation was conducted to elucidate whether atractylenolide-I (ATL-1), which is the main component of Atractylodes macrocephala Koidz, can sensitize triple-negative breast cancer (TNBC) cells to paclitaxel and investigate the possible mechanism involved. We discovered that ATL-1 could inhibit tumor cell migration and increase the sensitivity of tumor cells to paclitaxel. ATL-1 downregulated the expression and secretion of CTGF in TNBC cells. Apart from inhibiting TNBC cell migration via CTGF, ATL-1 downregulated the expression of CTGF in fibroblasts and decreased the ability of breast cancer cells to transform fibroblasts into cancer-associated fibroblasts (CAFs), which in turn increased the sensitivity of TNBC cells to paclitaxel. In a mouse model, we found that ATL-1 treatments could enhance the chemotherapeutic effect of paclitaxel on tumors and reduce tumor metastasis to the lungs and liver. Primary cultured fibroblasts derived from inoculated tumors in mice treated with ATL-1 combined with paclitaxel expressed relatively low levels of CAF markers. Collectively, our data indicate that ATL-1 can sensitize TNBC cells to paclitaxel by blocking CTGF expression and fibroblast activation and could be helpful in future research to determine the value of ATL-1 in the clinical setting.

Autophagy and cancer metabolism-The two-way interplay

Autophagy is an intracellular catabolic process that degrades cytoplasmic components for recycling in response to stressed conditions, such as nutrient deprivation. Dysregulation of autophagy is associated with various diseases, including cancer. Although autophagy plays dichotomous and context-dependent roles in cancer, evidence has emerged that cancer cells exploit autophagy for metabolic adaptation. Autophagy is upregulated in many cancer types through tumor cell-intrinsic proliferation demands and the hypoxic and nutrient-limited tumor microenvironment (TME). Autophagy-induced breakdown products then fuel into various metabolic pathways to supply tumor cells with energy and building blocks for biosynthesis and survival. This bidirectional regulation between autophagy and tumor constitutes a vicious cycle to potentiate tumor growth and therapy resistance. In addition, the pro-tumor functions of autophagy are expanded to host, including cells in TME and distant organs. Thus, inhibition of autophagy or autophagy-mediated metabolic reprogramming may be a promising strategy for anticancer therapy. Better understanding the metabolic rewiring mechanisms of autophagy for its pro-tumor effects will provide insights into patient treatment.

The Role of the BH4 Cofactor in Nitric Oxide Synthase Activity and Cancer Progression: Two Sides of the Same Coin

Cancer development is associated with abnormal proliferation, genetic instability, cell death resistance, metabolic reprogramming, immunity evasion, and metastasis. These alterations are triggered by genetic and epigenetic alterations in genes that control cell homeostasis. Increased reactive oxygen and nitrogen species (ROS, RNS) induced by different enzymes and reactions with distinct molecules contribute to malignant transformation and tumor progression by modifying DNA, proteins, and lipids, altering their activities. Nitric oxide synthase plays a central role in oncogenic signaling modulation and redox landscape. Overexpression of the three NOS isoforms has been found in innumerous types of cancer contributing to tumor growth and development. Although the main function of NOS is the production of nitric oxide (NO), it can be a source of ROS in some pathological conditions. Decreased tetrahydrobiopterin (BH4) cofactor availability is involved in NOS dysfunction, leading to ROS production and reduced levels of NO. The regulation of NOSs by BH4 in cancer is controversial since BH4 has been reported as a pro-tumoral or an antitumoral molecule. Therefore, in this review, the role of BH4 in the control of NOS activity and its involvement in the capabilities acquired along tumor progression of different cancers was described.

The transformation of cancer-associated fibroblasts: Current perspectives on the role of TGF-β in CAF mediated tumor progression and therapeutic resistance

Over the last few years, the Transforming growth factor- β (TGF-β) has been significantly considered as an effective and ubiquitous mediator of cell growth. The cytokine, TGF-β is being increasingly recognized as the most potent inducer of cancer cell initiation, differentiation, migration as well as progression through both the SMAD-dependent and independent pathways. There is growing evidence that supports the role of secretory cytokine TGF-β as a crucial mediator of tumor-stroma crosstalk. Contextually, the CAFs are the prominent component of tumor stroma that helps in tumor progression and onset of chemoresistance. The interplay between the CAFs and the tumor cells through the paracrine signals is facilitated by cytokine TGF-β to induce the malignant progression. Here in this review, we have dissected the most recent advancements in understanding the mechanisms of TGF-β induced CAF activation, their multiple origins, and most importantly their role in conferring chemoresistance. Considering the pivotal role of TGF-β in tumor perogression and associated stemness, it is one the proven clinical targets We have also included the clinical trials going on, targeting the TGF-β and CAFs crosstalk with the tumor cells. Ultimately, we have underscored some of the outstanding issues that must be deciphered with utmost importance to unravel the successful strategies of anti-cancer therapies.

Breast cancer fibroblasts and cross-talk

The breast tumor microenvironment is one of the crucial elements supporting breast cancer tumor progression and metastasis. The fibroblasts are the chief cellular component of the stromal microenvironment and are pathologically activated and differentiated into breast cancer-associated fibroblasts (CAFs). The catabolic phenotype of breast CAFs arises due to metabolic reprogramming of these fibroblasts under pseudo-hypoxic conditions. The metabolic intermediates and ATP produced by the breast CAFs are exploited by the neighboring cancer cells for energy generation. The growth factors, cytokines, and chemokines secreted by the CAFs help fuel tumor growth, invasion, and dissemination. Moreover, the interplay between breast CAFs and cancer cells, mediated by the growth factors, ROS, metabolic intermediates, exosomes, and catabolite transporters, aids in building a favorable microenvironment that promotes cancer cell proliferation, tumor progression, and metastasis. Therefore, identifying effective means to target the reprogrammed metabolism of the breast CAFs and the cross-communication between CAFs and cancer cells serve as promising strategies to develop anti-cancer therapeutics. Henceforth, the scope of the present review ranges from discussing the underlying characteristics of breast CAFs, mechanisms of metabolic reprogramming in breast CAFs, and the nature of interactions between breast CAFs and cancer cells to studying the intricacies of reprogrammed metabolism targeted cancer therapy.

Regulation of Cellular Senescence Is Independent from Profibrotic Fibroblast-Deposited ECM

Idiopathic pulmonary fibrosis (IPF) is a devastating lung disease with poor survival. Age is a major risk factor, and both alveolar epithelial cells and lung fibroblasts in this disease exhibit features of cellular senescence, a hallmark of ageing. Accumulation of fibrotic extracellular matrix (ECM) is a core feature of IPF and is likely to affect cell function. We hypothesize that aberrant ECM deposition augments fibroblast senescence, creating a perpetuating cycle favouring disease progression. In this study, primary lung fibroblasts were cultured on control and IPF-derived ECM from fibroblasts pretreated with or without profibrotic and prosenescent stimuli, and markers of senescence, fibrosis-associated gene expression and secretion of cytokines were measured. Untreated ECM derived from control or IPF fibroblasts had no effect on the main marker of senescence p16^Ink4a and p21^Waf1/Cip1. However, the expression of alpha smooth muscle actin (ACTA2) and proteoglycan decorin (DCN) increased in response to IPF-derived ECM. Production of the proinflammatory cytokines C-X-C Motif Chemokine Ligand 8 (CXCL8) by lung fibroblasts was upregulated in response to senescent and profibrotic-derived ECM. Finally, the profibrotic cytokines transforming growth factor β1 (TGF-β1) and connective tissue growth factor (CTGF) were upregulated in response to both senescent- and profibrotic-derived ECM. In summary, ECM deposited by IPF fibroblasts does not induce cellular senescence, while there is upregulation of proinflammatory and profibrotic cytokines and differentiation into a myofibroblast phenotype in response to senescent- and profibrotic-derived ECM, which may contribute to progression of fibrosis in IPF.

Emerging role of autophagy in anti-tumor immunity: Implications for the modulation of immunotherapy resistance

Immunotherapies such as CAR-T cell transfer and antibody-targeted therapy have produced promising clinical outcomes in patients with advanced and metastatic cancer that are resistant to conventional therapies. However, with increasing use of cancer immunotherapy in clinical treatment, multiple therapy-resistance mechanisms have gradually emerged. The tumor microenvironment (TME), an integral component of cancer, can significantly influence the therapeutic response. Thus, it is worth exploring the potential of TME in modulating therapy resistance, in the hope to devise novel strategies to reinforcing anti-cancer treatments such as immunotherapy. As a crucial recycling process in the complex TME, the role of autophagy in tumor immunity has been increasingly appreciated. Firstly, autophagy in tumor cells can affect their immune response through modulating MHC-I-antigen complexes, thus modulating immunogenic tumor cell death, changing functions of immune cells via secretory autophagy, reducing the NK- and CTL-mediated cell lysis and degradation of immune checkpoint proteins. Secondly, autophagy is critical for the differentiation, maturation and survival of immune cells in the TME and can significantly affect the immune function of these cells, thereby regulating the anti-tumor immune response. Thirdly, alteration of autophagic activity in stromal cells, especially in fibroblasts, can reconstruct the three-dimensional stromal environment and metabolic reprogramming in the TME. A number of studies have demonstrated that optimal induction or inhibition of autophagy may lead to effective therapeutic regimens when combined with immunotherapy. This review discusses the important roles of autophagy in tumor cells, immune cells and stromal cells in the context of tumor immunity, and the potential of combining the autophagy-based therapy with immunotherapy as novel therapeutic approaches against cancer.

Possibility for Transcriptional Targeting of Cancer-Associated Fibroblasts-Limitations and Opportunities

Cancer-associated fibroblasts (CAF) are attractive therapeutic targets in the tumor microenvironment. The possibility of using CAFs as a source of therapeutic molecules is a challenging approach in gene therapy. This requires transcriptional targeting of transgene expression by cis-regulatory elements (CRE). Little is known about which CREs can provide selective transgene expression in CAFs. We hypothesized that the promoters of FAP, CXCL12, IGFBP2, CTGF, JAG1, SNAI1, and SPARC genes, the expression of whose is increased in CAFs, could be used for transcriptional targeting. Analysis of the transcription of the corresponding genes revealed that unique transcription in model CAFs was characteristic for the CXCL12 and FAP genes. However, none of the promoters in luciferase reporter constructs show selective activity in these fibroblasts. The CTGF, IGFBP2, JAG1, and SPARC promoters can provide higher transgene expression in fibroblasts than in cancer cells, but the nonspecific viral promoters CMV, SV40, and the recently studied universal PCNA promoter have the same features. The patterns of changes in activity of various promoters relative to each other observed for human cell lines were similar to the patterns of activity for the same promoters both in vivo and in vitro in mouse models. Our results reveal restrictions and features for CAF transcriptional targeting.

Alpha-enolase (ENO1), identified as an antigen to monoclonal antibody 12C7, promotes the self-renewal and malignant phenotype of lung cancer stem cells by AMPK/mTOR pathway

BACKGROUND

Tumor-associated antigens (TAAs) can be targeted in cancer therapy. We previously identified a monoclonal antibody (mAb) 12C7, which presented anti-tumor activity in lung cancer stem cells (LCSCs). Here, we aimed to identify the target antigen for 12C7 and confirm its role in LCSCs.

METHODS

Immunofluorescence was used for antigen localization. After targeted antigen purification by electrophoresis and immunoblot, the antigen was identified by LC-MALDI-TOF/TOF mass spectrometry, immunofluorescence, and immunoprecipitation. The overexpression or silence of ENO1 was induced by lentiviral transduction. Self-renewal, growth, and invasion of LCSCs were evaluated by sphere formation, colony formation, and invasion assay, respectively. High-throughput transcriptome sequencing (RNA-seq) and bioinformatics analysis were performed to analyze downstream targets and pathways of targeted antigen.

RESULTS

Targeted antigen showed a surface antigen expression pattern, and the 43-55 kDa protein band was identified as α-enolase (ENO1). Self-renewal, growth, and invasion abilities of LCSCs were remarkably inhibited by ENO1 downregulation, while enhanced by ENO1 upregulation. RNA-seq and bioinformatics analysis eventually screened 4 self-renewal-related and 6 invasion-related differentially expressed genes. GSEA analysis and qRT-PCR verified that ENO1 regulated self-renewal, invasion-related genes, and pathways. KEGG pathway analysis and immunoblot demonstrated that ENO1 inactivated AMPK pathway and activated mTOR pathway in LCSCs.

CONCLUSIONS

ENO1 is identified as a targeted antigen of mAb 12C7 and plays a pivotal role in facilitating self-renewal, growth, and invasion of LCSCs. These findings provide a potent therapeutic target for the stem cell therapy for lung cancer and have potential to improve the anti-tumor activity of 12C7.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

Targeting CTGF in Cancer: An Emerging Therapeutic Opportunity

Despite the dramatic advances in cancer research over the decades, effective therapeutic strategies are still urgently needed. Increasing evidence indicates that connective tissue growth factor (CTGF), a multifunctional signaling modulator, promotes cancer initiation, progression, and metastasis by regulating cell proliferation, migration, invasion, drug resistance, and epithelial-mesenchymal transition (EMT). CTGF is also involved in the tumor microenvironment in most of the nodes, including angiogenesis, inflammation, and cancer-associated fibroblast (CAF) activation. In this review, we comprehensively discuss the expression of CTGF and its regulation, oncogenic role, clinical relevance, targeting strategies, and therapeutic agents. Herein, we propose that CTGF is a promising cancer therapeutic target that could potentially improve the clinical outcomes of cancer patients.

DNA damage response and breast cancer development: Possible therapeutic applications of ATR, ATM, PARP, BRCA1 inhibition

Breast cancer is the most common and significant cancers in females regarding the loss of life quality. Similar to other cancers, one of the etiologic factors in breast cancer is DNA damage. A plethora of molecules are responsible for sensing DNA damage and mediating actions which lead to DNA repair, senescence, cell cycle arrest and if damage is unbearable to apoptosis. In each of these, aberrations leading to unrepaired damage was resulted in uncontrolled proliferation and cancer. Another cellular function is autophagy defined as a process eliminating of unnecessary proteins in stress cases involved in pathogenesis of cancer. Knowing their role in cancer, scholars have tried to develop strategies in order to target DDR and autophagy. Further, the interactions of DDR and autophagy plus their regulatory role on each other have been focused simultaneously. The present review study has aimed to illustrate the importance of DDR and autophagy in breast cancer according to the related studies and uncover the relation between DDR and autophagy and its significance in breast cancer therapy.

Emerging Autophagy Functions Shape the Tumor Microenvironment and Play a Role in Cancer Progression - Implications for Cancer Therapy

The tumor microenvironment (TME) is a complex environment where cancer cells reside and interact with different types of cells, secreted factors, and the extracellular matrix. Additionally, TME is shaped by several processes, such as autophagy. Autophagy has emerged as a conserved intracellular degradation pathway for clearance of damaged organelles or aberrant proteins. With its central role, autophagy maintains the cellular homeostasis and orchestrates stress responses, playing opposite roles in tumorigenesis. During tumor development, autophagy also mediates autophagy-independent functions associated with several hallmarks of cancer, and therefore exerting several effects on tumor suppression and/or tumor promotion mechanisms. Beyond the concept of degradation, new different forms of autophagy have been described as modulators of cancer progression, such as secretory autophagy enabling intercellular communication in the TME by cargo release. In this context, the synthesis of senescence-associated secretory proteins by autophagy lead to a senescent phenotype. Besides disturbing tumor treatment responses, autophagy also participates in innate and adaptive immune signaling. Furthermore, recent studies have indicated intricate crosstalk between autophagy and the epithelial-mesenchymal transition (EMT), by which cancer cells obtain an invasive phenotype and metastatic potential. Thus, autophagy in the cancer context is far broader and complex than just a cell energy sensing mechanism. In this scenario, we will discuss the key roles of autophagy in the TME and surrounding cells, contributing to cancer development and progression/EMT. Finally, the potential intervention in autophagy processes as a strategy for cancer therapy will be addressed.

MicroRNA-223 decreases cell proliferation, migration, invasion, and enhances cell apoptosis in childhood acute lymphoblastic leukemia via targeting Forkhead box O 1

OBJECTIVE

Acute lymphoblastic leukemia (ALL) is a frequent malignancy in childhood. The present study was aimed to investigate the effect of miR-223 in ALL and its underlying molecular mechanisms.

METHODS

The mRNA expression of miR-223 and FOXO1 was detected by qRT-RCR in ALL children. The correlation between miR-223 and clinical indexes of ALL was determined. CCRF-CEM and NALM-6 cells were transfected with miR-223 mimic and miR-223 inhibitor, respectively. The proliferation, apoptosis, invasion and migration of CCRF-CEM and NALM-6 cells were measured by MTT, flow cytometry and transwell assay. The protein expression of FOXO1 was detected by Western blot. Additionally, dual-luciferase reporter and RNA pull-down assay were performed to investigate the target gene of miR-223 and validate their targeting relationship.

RESULTS

The mRNA expression of miR-223 was markedly down-regulated in ALL, but FOXO1 was up-regulated. The protein expression of FOXO1 was highly expressed in CCRF-CEM and NALM-6 cells. The expression of miR-223 was related to WBC, PLT, RBC and risk stratification. Overexpression of miR-223 not only inhibited cell proliferation, migration and invasion, but also induced cell apoptosis. Importantly, FOXO1 was a target gene of miR-223 in ALL cells. Silencing of FOXO1 reversed the effects of miR-223 inhibitor on cell proliferation, migration, invasion and apoptosis in ALL.

CONCLUSIONS

miR-223 could inhibit cell proliferation, migration and invasion, and promote apoptosis by targeting FOXO1 in ALL.

The updated landscape of tumor microenvironment and drug repurposing

Accumulating evidence shows that cellular and acellular components in tumor microenvironment (TME) can reprogram tumor initiation, growth, invasion, metastasis, and response to therapies. Cancer research and treatment have switched from a cancer-centric model to a TME-centric one, considering the increasing significance of TME in cancer biology. Nonetheless, the clinical efficacy of therapeutic strategies targeting TME, especially the specific cells or pathways of TME, remains unsatisfactory. Classifying the chemopathological characteristics of TME and crosstalk among one another can greatly benefit further studies exploring effective treating methods. Herein, we present an updated image of TME with emphasis on hypoxic niche, immune microenvironment, metabolism microenvironment, acidic niche, innervated niche, and mechanical microenvironment. We then summarize conventional drugs including aspirin, celecoxib, β-adrenergic antagonist, metformin, and statin in new antitumor application. These drugs are considered as viable candidates for combination therapy due to their antitumor activity and extensive use in clinical practice. We also provide our outlook on directions and potential applications of TME theory. This review depicts a comprehensive and vivid landscape of TME from biology to treatment.

The Double-Faced Role of Nitric Oxide and Reactive Oxygen Species in Solid Tumors

Disturbed redox homeostasis represents a hallmark of cancer phenotypes, affecting cellular metabolism and redox signaling. Since reactive oxygen and nitrogen species (ROS/RNS) are involved in regulation of proliferation and apoptosis, they may play a double-faced role in cancer, entailing protumorigenic and tumor-suppressing effects in early and later stages, respectively. In addition, ROS and RNS impact the activity and communication of all tumor constituents, mediating their reprogramming from anti- to protumorigenic phenotypes, and vice versa. An important role in this dichotomic action is played by the variable amounts of O₂ in the tumor microenvironment, which dictates the ultimate outcome of the influence of ROS/RNS on carcinogenesis. Moreover, ROS/RNS levels remarkably influence the cancer response to therapy. The relevance of ROS/RNS signaling in solid tumors is witnessed by the emergence of novel targeted treatments of solid tumors with compounds that target ROS/RNS action and production, such as tyrosine kinase inhibitors and monoclonal antibodies, which might contribute to the complexity of redox regulation in cancer. Prospectively, the dual role of ROS/RNS in the different stages of tumorigenesis through different impact on oxidation and nitrosylation may also allow development of tailored diagnostic and therapeutic approaches.

Cachexia Anorexia Syndrome and Associated Metabolic Dysfunction in Peritoneal Metastasis

Patients with peritoneal metastasis (PM) of gastrointestinal and gynecological origin present with a nutritional deficit characterized by increased resting energy expenditure (REE), loss of muscle mass, and protein catabolism. Progression of peritoneal metastasis, as with other advanced malignancies, is associated with cancer cachexia anorexia syndrome (CAS), involving poor appetite (anorexia), involuntary weight loss, and chronic inflammation. Eventual causes of mortality include dysfunctional metabolism and energy store exhaustion. Etiology of CAS in PM patients is multifactorial including tumor growth, host response, cytokine release, systemic inflammation, proteolysis, lipolysis, malignant small bowel obstruction, ascites, and gastrointestinal side effects of drug therapy (chemotherapy, opioids). Metabolic changes of CAS in PM relate more to a systemic inflammatory response than an adaptation to starvation. Metabolic reprogramming is required for cancer cells shed into the peritoneal cavity to resist anoikis (i.e., programmed cell death). Profound changes in hexokinase metabolism are needed to compensate ineffective oxidative phosphorylation in mitochondria. During the development of PM, hypoxia inducible factor-1α (HIF-1α) plays a key role in activating both aerobic and anaerobic glycolysis, increasing the uptake of glucose, lipid, and glutamine into cancer cells. HIF-1α upregulates hexokinase II, phosphoglycerate kinase 1 (PGK1), pyruvate dehydrogenase kinase (PDK), pyruvate kinase muscle isoenzyme 2 (PKM2), lactate dehydrogenase (LDH) and glucose transporters (GLUT) and promotes cytoplasmic glycolysis. HIF-1α also stimulates the utilization of glutamine and fatty acids as alternative energy substrates. Cancer cells in the peritoneal cavity interact with cancer-associated fibroblasts and adipocytes to meet metabolic demands and incorporate autophagy products for growth. Therapy of CAS in PM is challenging. Optimal nutritional intake alone including total parenteral nutrition is unable to reverse CAS. Pressurized intraperitoneal aerosol chemotherapy (PIPAC) stabilized nutritional status in a significant proportion of PM patients. Agents targeting the mechanisms of CAS are under development.

Antitumor and antiviral activities of 4-substituted 1,2,3-triazolyl-2,3-dibenzyl-L-ascorbic acid derivatives

Two series of 6-(1,2,3-triazolyl)-2,3-dibenzyl-l-ascorbic acid derivatives with the hydroxyethylene (8a−8u) and ethylidene linkers (10c−10p) were synthesized and evaluated for their antiproliferative activity against seven malignant tumor cell lines and antiviral activity against a broad range of viruses. Conformationally unrestricted spacer between the lactone and 1,2,3-triazole units in 8a−8u series had a profound effect on antitumor activity. Besides, the introduction of a long side chain at C-4 of 1,2,3-triazole that led to the synthesis of decyl-substituted 2,3-dibenzyl-l-ascorbic acid 8m accounted for a selective and potent antiproliferative activity on breast cancer MCF-7 cells cells in the nM range. Further analysis showed that compound 8m strongly enhanced expression of hypoxia inducible transcription factor 1 α (HIF-1α) and to some extent decreased expression of nitric oxide synthase 2 (NOS2) suggesting its role in regulating HIF-1α signalling pathway. The p-methoxyphenyl-substituted derivative 10g displayed specific anti-cytomegalovirus (CMV) potential, whereas aliphatic-substituted derivatives 8l and 8m had the most potent, yet relatively non-specific, anti-varicella-zoster (VZV) activity.

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Two series of 1,2,3-triazolyl 2,3-dibenzyl-l-ascorbic acid conjugates were synthesized.

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Conformationally unrestricted spacer had a major effect on antitumor activities.

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Decyl-substituted l-ascorbic acid 8m caused inhibition of breast cancer MCF-7 cells in the nM range.

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8m increased the expression of hypoxia inducible transcription factor HIF-1α.

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p-Methoxyphenyl-substituted derivative 10g had specific anti-CMV activity.

Reactive Oxygen Species in the Tumor Microenvironment: An Overview

Reactive oxygen species (ROS) are important signaling molecules in cancer. The level of ROS will determine physiological effects. While high levels of ROS can cause damage to tissues and cell death, low levels of ROS can have a proliferative effect. ROS are produced by tumor cells but also cellular components that make up the tumor microenvironment (TME). In this review, we discuss the mechanisms by which ROS can affect the TME with particular emphasis on tumor-infiltrating leukocytes. Greater insight into ROS biology in this setting may allow for therapeutic manipulation of ROS levels in order to remodel the tumor microenvironment and increase anti-tumor activity.

MicroRNA-212-3p inhibits the Proliferation and Invasion of Human Hepatocellular Carcinoma Cells by Suppressing CTGF expression

MicroRNA-212-3p inhibits several human cancers but its effects on hepatocellular carcinoma (HCC) remain unclear. In this study, we show that miR-212-3p is down-regulated in HCC cell lines and tissues, and correlates with vascular invasion (p = 0.001), and the absence of capsule formation (p = 0.009). We found that miR-212-3p influenced the epithelial to mesenchymal transition (EMT) of HCCLM3 and Huh7 cells. Mechanistically, miR-212-3p repressed cell invasion through the suppression of connective tissue growth factor (CTGF). We therefore validate the anti-HCC effects of miR-212-3p through its ability to suppress CTGF and subsequent EMT.

Pharmacologic treatment with CPI-613 and PS48 decreases mitochondrial membrane potential and increases quantity of autolysosomes in porcine fibroblasts

A metabolic phenomenon known as the Warburg effect has been characterized in certain cancerous cells, embryonic stem cells, and other rapidly proliferative cell types. Previously, our attempts to induce a Warburg-like state pharmaceutically via CPI-613 and PS48 treatment did augment metabolite production and gene expression; however, this treatment demonstrated a Reverse Warburg effect phenotype observed in cancer-associated stroma. In the current study, we inquired whether the mitochondria were affected by the aforementioned pharmaceutical treatment as observed in cancerous stromal fibroblasts. While the pharmaceutical agents decreased mitochondrial membrane potential in porcine fetal fibroblasts, the number and size of mitochondria were similar, as was the overall cell size. Moreover, the fibroblasts that were treated with CPI-613 and PS48 for a week had increased numbers of large autolysosome vesicles. This coincided with increased intensity of LysoTracker staining in treated cells as observed by flow cytometry. Treated fibroblasts thus may utilize changes in metabolism and autophagy to mitigate the damage of treatment with pharmaceutical agents. These findings shed light on how these pharmaceutical agents interact and how treated cells augment metabolism to sustain viability.

Autophagy and senescence: A new insight in selected human diseases

Senescence and autophagy play important roles in homeostasis. Cellular senescence and autophagy commonly cause several degenerative processes, including oxidative stress, DNA damage, telomere shortening, and oncogenic stress; hence, both events are known to be interrelated. Autophagy is well known for its disruptive effect on human diseases, and it is currently proposed to have a direct effect on triggering senescence and quiescence. However, it is yet to be proven whether autophagy has a positive or negative impact on senescence. It is known that elevated levels of autophagy induce cell death, whereas inadequate autophagy can trigger cellular senescence. Both have important roles in human diseases such as aging, renal degeneration, neurodegenerative disorders, and cancer. Therefore, this review aims to highlight the relevance of senescence and autophagy in selected human ailments through a summary of recent findings on the connection and effects of autophagy and senescence in these diseases.

The effects and the mechanisms of autophagy on the cancer-associated fibroblasts in cancer

Cancer-associated fibroblasts (CAFs) plays an essential role in cancer cell growth, metabolism and immunoreaction. Autophagy is an intracellular self-degradative process that balances cell energy source and regulates tissue homeostasis. Targeting autophagy has gained interest with multiple preclinical and clinical trials, such as the pharmacological inhibitor chloroquine or the inducer rapamycin, especially in exploiting its ability to modulate the secretory capability of CAFs to enhance drug delivery or inhibit it to prevent its influence on cancer cell chemoresistance. In this review, we summarize the reports on autophagy in cancer-associated fibroblasts by detailing the mechanism and role of autophagy in CAFs, including the hypoxic-autophagy positive feedback cycle, the metabolic cross-talk between CAFs and tumors induced by autophagy, CAFs secreted cytokines promote cancer survival by secretory autophagy, CAFs autophagy-induced EMT, stemness, senescence and treatment sensitivity, as well as the research of antitumor chemicals, miRNAs and lncRNAs. Additionally, we discuss the evidence of molecules in CAFs that are relevant to autophagy and the contribution to sensitive treatments as a potential target for cancer treatment.

The multifaceted role of autophagy in cancer and the microenvironment

Autophagy is a crucial recycling process that is increasingly being recognized as an important factor in cancer initiation, cancer (stem) cell maintenance as well as the development of resistance to cancer therapy in both solid and hematological malignancies. Furthermore, it is being recognized that autophagy also plays a crucial and sometimes opposing role in the complex cancer microenvironment. For instance, autophagy in stromal cells such as fibroblasts contributes to tumorigenesis by generating and supplying nutrients to cancerous cells. Reversely, autophagy in immune cells appears to contribute to tumor‐localized immune responses and among others regulates antigen presentation to and by immune cells. Autophagy also directly regulates T and natural killer cell activity and is required for mounting T‐cell memory responses. Thus, within the tumor microenvironment autophagy has a multifaceted role that, depending on the context, may help drive tumorigenesis or may help to support anticancer immune responses. This multifaceted role should be taken into account when designing autophagy‐based cancer therapeutics. In this review, we provide an overview of the diverse facets of autophagy in cancer cells and nonmalignant cells in the cancer microenvironment. Second, we will attempt to integrate and provide a unified view of how these various aspects can be therapeutically exploited for cancer therapy.

Paracrine HGF/c-MET enhances the stem cell-like potential and glycolysis of pancreatic cancer cells via activation of YAP/HIF-1α

Pancreatic stellate cells (PSCs), a pivotal component of the tumor microenvironment, contribute to tumor growth and metastasis. PSC-derived factors are essential for triggering the generation and maintenance of cancer stem cells (CSCs). However, the mechanisms by which paracrine signals regulate CSC-like properties such as glycolytic metabolism have not been fully elucidated. Here, we report that two pancreatic cancer cell lines, Panc-1 and MiaPaCa-2, reacted differently when treated with hepatocyte growth factor (HGF) secreted from PSCs. MiaPaCa-2 cells showed little response with regard to CSC-like properties after HGF treatment. We have shown that in Panc-1 cells by activating its cognate receptor c-MET, paracrine HGF resulted in YAP nuclear translocation and HIF-1α stabilization, thereby promoting the expression of CSC pluripotency markers NANOG, OCT-4 and SOX-2 and tumor sphere formation ability. Furthermore, HGF/c-MET/YAP/HIF-1α signaling enhanced the expression of Hexokinase 2 (HK2) and promoted glycolytic metabolism, which may facilitate CSC-like properties. Collectively, our study demonstrated that HGF/c-MET modulates tumor metabostemness by regulating YAP/HIF-1α and may hold promise as a potential therapeutic target against pancreatic cancer.

MiR-218 regulates epithelial-mesenchymal transition and angiogenesis in colorectal cancer via targeting CTGF

Background

Endothelial-to-mesenchymal transition (EMT) and angiogenesis play important roles in colorectal cancer (CRC) development. Connective tissue growth factor (CTGF) has been reported to promote several kinds of cancer progression and miR-218 has been identified as a tumor suppressor miRNA. However, little is known about the function of miR-218 in CRC. Here we investigated the effects of miR-218 on EMT and angiogenesis process in CRC cells. As well, the relation between miR-218 and CTGF was identified. The mechanism of miR-218’s function was illustrated.

Methods

CRC cell lines were transfected with miR-218 mimics. Proliferation, migration and angiogenesis were identified by MTT assay, Transwell assay, colony formation assay and tube formation assay. Protein and mRNA expression levels of associated genes were measured by Western blotting and RT-PCR. Dual luciferase assay was used to determine the relation of miR-218 and CTGF.

Results

miR-218 was down-regulated in CRC cell lines and over expression of miR-218 could significantly inhibit EMT and angiogenesis. CTGF was a direct target of miR-218. Up regulation of CTGF level after miR-218 transfection could sufficiently rescue the suppression effects on EMT and angiogenesis.

Conclusion

miR-218 directly targets CTGF and inhibits its expression, leading to suppression on EMT and angiogenesis of CRC cells. miR-218 might be used as potential therapeutic strategy for CRC treatment.

Metabolic Reprogramming of Cancer Associated Fibroblasts: The Slavery of Stromal Fibroblasts

Cancer associated fibroblasts (CAFs) are the main stromal cell type of solid tumour microenvironment and undergo an activation process associated with secretion of growth factors, cytokines, and paracrine interactions. One of the important features of solid tumours is the metabolic reprogramming that leads to changes of bioenergetics and biosynthesis in both tumour cells and CAFs. In particular, CAFs follow the evolution of tumour disease and acquire a catabolic phenotype: in tumour tissues, cancer cells and tumour microenvironment form a network where the crosstalk between cancer cells and CAFs is associated with cell metabolic reprogramming that contributes to CAFs activation, cancer growth, and progression and evasion from cancer therapies. In this regard, the study of CAFs metabolic reprogramming could contribute to better understand their activation process, the interaction between stroma, and cancer cells and could offer innovative tools for the development of new therapeutic strategies able to eradicate the protumorigenic activity of CAFs. Therefore, this review focuses on CAFs metabolic reprogramming associated with both differentiation process and cancer and stromal cells crosstalk. Finally, therapeutic responses and potential anticancer strategies targeting CAFs metabolic reprogramming are reviewed.

Mechanisms and context underlying the role of autophagy in cancer metastasis

Macroautophagy/autophagy is a fundamental cellular degradation mechanism that maintains cell homeostasis, regulates cell signaling, and promotes cell survival. Its role in promoting tumor cell survival in stress conditions is well characterized, and makes autophagy an attractive target for cancer therapy. Emerging research indicates that autophagy also influences cancer metastasis, which is the primary cause of cancer-associated mortality. However, data demonstrate that the regulatory role of autophagy in metastasis is multifaceted, and includes both metastasis-suppressing and -promoting functions. The metastasis-suppressing functions of autophagy, in particular, have important implications for autophagy-based treatments, as inhibition of autophagy may increase the risk of metastasis. In this review, we discuss the mechanisms and context underlying the role of autophagy in metastasis, which include autophagy-mediated regulation of focal adhesion dynamics, integrin signaling and trafficking, Rho GTPase-mediated cytoskeleton remodeling, anoikis resistance, extracellular matrix remodeling, epithelial-to-mesenchymal transition signaling, and tumor-stromal cell interactions. Through this, we aim to clarify the context-dependent nature of autophagy-mediated metastasis and provide direction for further research investigating the role of autophagy in cancer metastasis.

Reverse of non-small cell lung cancer drug resistance induced by cancer-associated fibroblasts via a paracrine pathway

The tumor microenvironment orchestrates the sustained growth, metastasis and recurrence of cancer. As an indispensable component of the tumor microenvironment, cancer-associated fibroblasts (CAF) are considered as an essential synthetic machine producing various tumor components, leading to cancer sustained stemness, drug resistance and tumor recurrence. Here, we developed a sustainable primary culture of lung cancer cells fed with lung cancer-associated fibroblasts, resulting in enrichment and acquisition of drug resistance in cancer cells. Moreover, IGF2/AKT/Sox2/ABCB1 signaling activation in cancer cells was observed in the presence of CAF, which induces upregulation of P-glycoprotein expression and the drug resistance of non-small cell lung cancer cells. Our results demonstrated that CAF cells constitute a mechanism for cancer drug resistance. Thus, traditional chemotherapy combined with insulin-like growth factor 2 (IGF2) signaling inhibitor may present an innovative therapeutic strategy for non-small cell lung cancer therapy.

HIF1α deletion facilitates adipose stem cells to repair renal fibrosis in diabetic mice

Adipose stem cell (ASC) transplantation is a promising therapeutic strategy for diabetic renal fibrosis. Hypoxia-inducible factor 1α (HIF1α) is a negative regulatory factor of mitochondrial function. In the current study, we aimed to explore if HIF1α deletion protects against hyperglycemia-induced ASC damage and enhances the therapeutic efficiency of ASCs in diabetic renal fibrosis. Our data indicated that HIF1α was upregulated in ASCs in response to high glucose stimulation. Higher HIF1α expression was associated with ASC apoptosis and proliferation arrest. Loss of HIF1α activated mitophagy protecting ASCs against high glucose-induced apoptosis via preserving mitochondrial function. Transplanting HIF1α-deleted ASCs in db/db mice improved the abnormalities in glucose metabolic parameters, including the levels of glucose, insulin, C-peptide, HbA1c, and inflammatory markers. In addition, the engraftment of HIF1α-modified ASCs also reversed renal function, decreased renal hypertrophy, and ameliorated renal histological changes in db/db mice. Functional studies confirmed that HIF1α-modified ASCs reduced renal fibrosis. Collectively, our results demonstrate that ASCs may be a promising therapeutic treatment for ameliorating diabetes and the development of renal fibrosis and that the loss of HIF1α in ASCs may further increase the efficiency of stem cell-based therapy. These findings provide a new understanding about the protective effects of HIF1α silencing on ASCs and offer a new strategy for promoting the therapeutic efficacy of ASCs in diabetic renal fibrosis.

miR-31 affects colorectal cancer cells by inhibiting autophagy in cancer-associated fibroblasts

Autophagy is a double-edged sword in tumor development. Recent studies have found that miRNAs have an inhibitory effect on the regulation of autophagy. It has been reported that miR-31 plays an important role in the development of colorectal cancer. However, what role miR-31 plays in colorectal cancer-associated fibroblasts (CAFs) has not been determined. In this study, we confirmed that the expression of miR-31 in CAFs was higher than in normal colorectal fibroblasts (NFs). We also found that treatment of CAFs with miR-31 mimic inhibited the expression of the autophagy-related genes Beclin-1, ATG, DRAM and LC3. In addition, we found up-regulation of miR-31 significantly affected colorectal cancer cell behaviors, including proliferation, invasion and apoptosis. Also, up-regulation of miR-31 in CAF could increase the radiosensitivity of colorectal cancer cells co-cultured with CAF. In summary, miR-31 can inhibit autophagy in colorectal CAFs, affect colorectal cancer development, and increase the radiosensitivity of colorectal cancer cells co-cultured with CAF. We hypothesize that miR-31 may become a new target of treatments for colorectal cancer.

Monocyte-derived factors including PLA2G7 induced by macrophage-nasopharyngeal carcinoma cell interaction promote tumor cell invasiveness

The non-keratinizing undifferentiated subtype of nasopharyngeal carcinoma (NPC) is a malignancy characterized by an intimate relationship between neoplastic cells and a non-neoplastic lymphoid component. Tumor-associated macrophages (TAMs) foster tumor progression through production of soluble mediators that support proliferation, angiogenesis, survival and invasion of malignant cells. However, the role of macrophages in the progression of NPC remains poorly understood. This study aims to investigate the functional and phenotypic changes that occur to macrophages in macrophage-NPC cell co-culture systems, and how these changes influence tumor cells. We found that monocytes, including THP-1 cells and primary human monocytes, co-cultured with C666-1 NPC cells upregulate expression of pro-inflammatory cytokines at the early stages, followed by the induction of metastasis-related genes and interferon-stimulated genes at the later stage of coculture, indicating that TAMs are “educated” by NPC cells for cancer progression. Importantly, the induction of these factors from the TAMs was also found to enhance the migratory capabilities of the NPC cells. We have also identified one of these macrophage-derived factor, phospholipase A2 Group 7 (PLA2G7), to be important in regulating tumor cell migration and a novel tumor-promoting factor in NPC. Further studies to characterize the role of PLA2G7 in tumor metastasis may help determine its potential as a therapeutic target in NPC.

The peritoneal "soil" for a cancerous "seed": a comprehensive review of the pathogenesis of intraperitoneal cancer metastases

Various types of tumors, particularly those originating from the ovary and gastrointestinal tract, display a strong predilection for the peritoneal cavity as the site of metastasis. The intraperitoneal spread of a malignancy is orchestrated by a reciprocal interplay between invading cancer cells and resident normal peritoneal cells. In this review, we address the current state-of-art regarding colonization of the peritoneal cavity by ovarian, colorectal, pancreatic, and gastric tumors. Particular attention is paid to the pro-tumoral role of various kinds of peritoneal cells, including mesothelial cells, fibroblasts, adipocytes, macrophages, the vascular endothelium, and hospicells. Anatomo-histological considerations on the pro-metastatic environment of the peritoneal cavity are presented in the broader context of organ-specific development of distal metastases in accordance with Paget's "seed and soil" theory of tumorigenesis. The activity of normal peritoneal cells during pivotal elements of cancer progression, i.e., adhesion, migration, invasion, proliferation, EMT, and angiogenesis, is discussed from the perspective of well-defined general knowledge on a hospitable tumor microenvironment created by the cellular elements of reactive stroma, such as cancer-associated fibroblasts and macrophages. Finally, the paper addresses the unique features of the peritoneal cavity that predispose this body compartment to be a niche for cancer metastases, presents issues that are topics of an ongoing debate, and points to areas that still require further in-depth investigations.

Phosphoglyceric acid mutase-1 contributes to oncogenic mTOR-mediated tumor growth and confers non-small cell lung cancer patients with poor prognosis

As a hallmark of cancer, the Warburg effect (aerobic glycolysis) confers a selective advantage for the survival and proliferation of cancer cells. Due to frequent aberration of upstream proto-oncogenes and tumor suppressors, hyperactive mammalian/mechanistic target of rapamycin (mTOR) is a potent inducer of the Warburg effect. Here, we report that overexpression of a glycolytic enzyme, phosphoglyceric acid mutase-1 (PGAM1), is critical to oncogenic mTOR-mediated Warburg effect. mTOR stimulated PGAM1 expression through hypoxia-inducible factor 1α-mediated transcriptional activation. Blockage of PGAM1 suppressed mTOR-dependent glycolysis, cell proliferation, and tumorigenesis. PGAM1 expression and mTOR activity were positively correlated in non-small cell lung cancer (NSCLC) tissues and PGAM1 abundance was an adverse predictor for patient survival. PGAM1 is thus a downstream effector of mTOR signaling pathway and mTOR-PGAM1 signaling cascade may contribute to the development of Warburg effect observed in cancer. We consider PGAM1 as a novel prognostic biomarker for NSCLC and a therapeutic target for cancer.