Participation of CCL1 in Snail-Positive Fibroblasts in Colorectal Cancer Contribute to 5-Fluorouracil/Paclitaxel Chemoresistance

Drug resistance and tumor immune microenvironment: An overview of current understandings (Review)

The use of antitumor drugs represents a reliable strategy for cancer therapy. Unfortunately, drug resistance has become increasingly common and contributes to tumor metastasis and local recurrence. The tumor immune microenvironment (TME) consists of immune cells, cytokines and immunomodulators, and collectively they influence the response to treatment. Epigenetic changes including DNA methylation and histone modification, as well as increased drug exportation have been reported to contribute to the development of drug resistance in cancers. In the past few years, the majority of studies on tumors have only focused on the development and progression of a tumor from a mechanistic standpoint; few studies have examined whether the changes in the TME can also affect tumor growth and drug resistance. Recently, emerging evidence have raised more concerns regarding the role of TME in the development of drug resistance. In the present review, it was discussed how the suppressive TME adapts to drug resistance characterized by the cooperation of immune cells, cytokines, immunomodulators, stromal cells and extracellular matrix. Furthermore, it was reviewed how these immunological or metabolic changes alter immuno‑surveillance and thus facilitate tumor drug resistance. In addition, potential targets present in the TME for developing novel therapeutic strategies to improve individualized therapy for cancer treatment were revealed.

Advances in targeting cancer-associated fibroblasts through single-cell spatial transcriptomic sequencing

Cancer-associated fibroblasts (CAFs) are the major components of the tumor microenvironment and are related to tumor proliferation, metastasis, relapse, and drug resistance. With the development of sequencing technologies, single-cell RNA sequencing has become a popular method for identifying CAFs in the tumor microenvironment. Whereas the drawbacks of CAFs, such as the lack of a spatial landscape, still exist, recent research has utilized spatial transcriptomics combined with single-cell RNA sequencing to address this issue. These multiomics analyses can resolve the single-cell resolution problem in spatial transcriptomics. In this review, we summarized the recent literature regarding the targeting of CAFs to address drug resistance, angiogenesis, metabolic reprogramming and metastasis in tumor tissue.

Sensing antibody functions with a novel CCR8-responsive engineered cell

Human chemokine receptor 8 (CCR8) is a promising drug target for immunotherapy of cancer and autoimmune diseases. Monoclonal antibody-based CCR8 targeted treatment shows significant inhibition in tumor growth. The inhibition of CCR8 results in the improvement of antitumor immunity and patient survival rates by regulating tumor-resident regulatory T cells. Recently monoclonal antibody drug development targeting CCR8 has become a research hotspot, which also promotes the advancement of antibody evaluation methods. Therefore, we constructed a novel engineered customized cell line HEK293-cAMP-biosensor-CCR8 combined with CCR8 and a cAMP-biosensor reporter. It can be used for the detection of anti-CCR8 antibody functions like specificity and biological activity, in addition to the detection of antibody-dependent cell-mediated cytotoxicity and antibody-dependent-cellular-phagocytosis. We obtained a new CCR8 mAb 22H9 and successfully verified its biological activities with HEK293-cAMP-biosensor-CCR8. Our reporter cell line has high sensitivity and specificity, and also offers a rapid kinetic detection platform for evaluating anti-CCR8 antibody functions.

Reduced chemokine C-C motif ligand 1 expression may negatively regulate colorectal cancer progression at liver metastatic sites

Colorectal cancer (CRC) liver metastasis, albeit a stage-IV disease, is completely curable by surgical resection in selected patients. In addressing the molecular basics of this phenomenon, differentially expressed genes at primary and liver metastatic sites were screened by RNA sequencing with the use of paraffin-embedded surgical specimens. Chemokine C-C motif ligand 1 (CCL1), a chemotactic factor for a ligand of the chemokine C-C motif receptor 8 (CCR8), was isolated as one of the differentially expressed genes. Histological analysis revealed that the number of CCL1-positive cells, mainly tumour associated macrophages (TAMs) located in the stroma of CRC, decreased significantly at liver metastatic sites, while the expression level of CCR8 on CRC remained unchanged. To explore the biological significance of the CCL1-CCR8 axis in CRC, CCR8-positive CRC cell line Colo320DM was used to assess the effect of the CCL1-CCR8 axis on major signalling pathways, epithelial mesenchymal transition induction and cell motility. Upon stimulation of recombinant CCL1 (rCCL1), phosphorylation of AKT was observed in Colo320DM cells; on the other hand, the corresponding significant increase in MMP-2 levels demonstrated by RT-qPCR was nullified by siRNA (siCCR8). In the scratch test, rCCL1 treatment significantly increased the motility of Colo320DM cells, which was similarly nullified by siCCR8. Thus, the activation of the CCL1-CCR8 axis is a positive regulator of CRC tumour progression. Reduced CCL1 expression of TAMs at liver metastatic sites may partly explain the unique slow tumour progression of CRC, thus providing for a grace period for radical resection of metastatic lesions.

Heterotypic signaling of cancer-associated fibroblasts in shaping the cancer cell drug resistance

The context-dependent reciprocal interaction between the cancer cells and surrounding fibroblasts is imperative for regulating malignant potential, metabolic reprogramming, immunosuppression, and ECM deposition. However, recent evidence also suggests that cancer-associated fibroblasts induce chemoresistance in cancer cells to various anticancer regimens. Because of the protumorigenic function of cancer-associated fibroblasts, these stromal cell types have emerged as fascinating therapeutic targets for cancer. However, this notion was recently challenged by studies that targeted cancer-associated fibroblasts and highlighted the underlying heterogeneity by identifying a subset of these cells with tumor-restricting functions. Hence, it is imperative to understand the heterogeneity and heterotypic signaling of cancer-associated fibroblasts to target tumor-promoting signaling processes by sparing tumor-restricting ones. In this review, we discuss the heterogeneity and heterotypic signaling of cancer-associated fibroblasts in shaping drug resistance and also list the cancer-associated fibroblast-targeting therapeutics.

Signaling pathways in cancer-associated fibroblasts: recent advances and future perspectives

As a critical component of the tumor microenvironment (TME), cancer-associated fibroblasts (CAFs) play important roles in cancer initiation and progression. Well-known signaling pathways, including the transforming growth factor-β (TGF-β), Hedgehog (Hh), Notch, Wnt, Hippo, nuclear factor kappa-B (NF-κB), Janus kinase (JAK)/signal transducer and activator of transcription (STAT), mitogen-activated protein kinase (MAPK), and phosphoinositide 3-kinase (PI3K)/AKT pathways, as well as transcription factors, including hypoxia-inducible factor (HIF), heat shock transcription factor 1 (HSF1), P53, Snail, and Twist, constitute complex regulatory networks in the TME to modulate the formation, activation, heterogeneity, metabolic characteristics and malignant phenotype of CAFs. Activated CAFs remodel the TME and influence the malignant biological processes of cancer cells by altering the transcriptional and secretory characteristics, and this modulation partially depends on the regulation of signaling cascades. The results of preclinical and clinical trials indicated that therapies targeting signaling pathways in CAFs demonstrated promising efficacy but were also accompanied by some failures (e.g., NCT01130142 and NCT01064622). Hence, a comprehensive understanding of the signaling cascades in CAFs might help us better understand the roles of CAFs and the TME in cancer progression and may facilitate the development of more efficient and safer stroma-targeted cancer therapies. Here, we review recent advances in studies of signaling pathways in CAFs and briefly discuss some future perspectives on CAF research.

Marine-Inspired Drugs and Biomaterials in the Perspective of Pancreatic Cancer Therapies

Despite its low prevalence, pancreatic cancer (PC) is one of the deadliest, typically characterised as silent in early stages and with a dramatically poor prognosis when in its advanced stages, commonly associated with a high degree of metastasis. Many efforts have been made in pursuing innovative therapeutical approaches, from the search for new cytotoxic drugs and other bioactive compounds, to the development of more targeted approaches, including improved drug delivery devices. Marine biotechnology has been contributing to this quest by providing new chemical leads and materials originating from different organisms. In this review, marine biodiscovery for PC is addressed, particularly regarding marine invertebrates (namely sponges, molluscs, and bryozoans), seaweeds, fungi, and bacteria. In addition, the development of biomaterials based on marine-originating compounds, particularly chitosan, fucoidan, and alginate, for the production of advanced cancer therapies, is also discussed. The key role that drug delivery can play in new cancer treatments is highlighted, as therapeutical outcomes need to be improved to give further hope to patients.

Cancer-Associated Fibroblasts: The Origin, Biological Characteristics and Role in Cancer-A Glance on Colorectal Cancer

Simple Summary

Tumor microenvironment is a major contributor to tumor growth, metastasis and resistance to therapy. It consists of many cancer-associated fibroblasts (CAFs), which derive from different types of cells. CAFs detected in different tumor types are linked to poor prognosis, as in the case of colorectal cancer. Although their functions differ according to their subtype, their detection is not easy, and there are no established markers for such detection. They are possible targets for therapeutic treatment. Many trials are ongoing for their use as a prognostic factor and as a treatment target. More research remains to be carried out to establish their role in prognosis and treatment.

Abstract

The therapeutic approaches to cancer remain a considerable target for all scientists around the world. Although new cancer treatments are an everyday phenomenon, cancer still remains one of the leading mortality causes. Colorectal cancer (CRC) remains in this category, although patients with CRC may have better survival compared with other malignancies. Not only the tumor but also its environment, what we call the tumor microenvironment (TME), seem to contribute to cancer progression and resistance to therapy. TME consists of different molecules and cells. Cancer-associated fibroblasts are a major component. They arise from normal fibroblasts and other normal cells through various pathways. Their role seems to contribute to cancer promotion, participating in tumorigenesis, proliferation, growth, invasion, metastasis and resistance to treatment. Different markers, such as a-SMA, FAP, PDGFR-β, periostin, have been used for the detection of cancer-associated fibroblasts (CAFs). Their detection is important for two main reasons; research has shown that their existence is correlated with prognosis, and they are already under evaluation as a possible target for treatment. However, extensive research is warranted.

Chemokines in progression, chemoresistance, diagnosis, and prognosis of colorectal cancer

Plenty of factors affect the oncogenesis and progression of colorectal cancer in the tumor microenvironment, including various immune cells, stromal cells, cytokines, and other factors. Chemokine is a member of the cytokine superfamily. It is an indispensable component in the tumor microenvironment. Chemokines play an antitumor or pro-tumor role by recruitment or polarization of recruiting immune cells. Meanwhile, chemokines, as signal molecules, participate in the formation of a cross talk among signaling pathways and non-coding RNAs, which may be involved in promoting tumor progression. In addition, they also function in immune escape. Chemokines are related to drug resistance of tumor cells and may even provide reference for the diagnosis, therapy, and prognosis of patients with colorectal cancer.

Colorectal Cancer-Infiltrating Regulatory T Cells: Functional Heterogeneity, Metabolic Adaptation, and Therapeutic Targeting

Colorectal cancer (CRC) is a heterogeneous disease with one of the highest rates of incidence and mortality among cancers worldwide. Understanding the CRC tumor microenvironment (TME) is essential to improve diagnosis and treatment. Within the CRC TME, tumor-infiltrating lymphocytes (TILs) consist of a heterogeneous mixture of adaptive immune cells composed of mainly anti-tumor effector T cells (CD4+ and CD8+ subpopulations), and suppressive regulatory CD4+ T (Treg) cells. The balance between these two populations is critical in anti-tumor immunity. In general, while tumor antigen-specific T cell responses are observed, tumor clearance frequently does not occur. Treg cells are considered to play an important role in tumor immune escape by hampering effective anti-tumor immune responses. Therefore, CRC-tumors with increased numbers of Treg cells have been associated with promoting tumor development, immunotherapy failure, and a poorer prognosis. Enrichment of Treg cells in CRC can have multiple causes including their differentiation, recruitment, and preferential transcriptional and metabolic adaptation to the TME. Targeting tumor-associated Treg cell may be an effective addition to current immunotherapy approaches. Strategies for depleting Treg cells, such as low-dose cyclophosphamide treatment, or targeting one or more checkpoint receptors such as CTLA-4 with PD-1 with monoclonal antibodies, have been explored. These have resulted in activation of anti-tumor immune responses in CRC-patients. Overall, it seems likely that CRC-associated Treg cells play an important role in determining the success of such therapeutic approaches. Here, we review our understanding of the role of Treg cells in CRC, the possible mechanisms that support their homeostasis in the tumor microenvironment, and current approaches for manipulating Treg cells function in cancer.

Drug Resistance in Colorectal Cancer: From Mechanism to Clinic

Colorectal cancer (CRC) is one of the leading causes of death worldwide. The 5-year survival rate is 90% for patients with early CRC, 70% for patients with locally advanced CRC, and 15% for patients with metastatic CRC (mCRC). In fact, most CRC patients are at an advanced stage at the time of diagnosis. Although chemotherapy, molecularly targeted therapy and immunotherapy have significantly improved patient survival, some patients are initially insensitive to these drugs or initially sensitive but quickly become insensitive, and the emergence of such primary and secondary drug resistance is a significant clinical challenge. The most direct cause of resistance is the aberrant anti-tumor drug metabolism, transportation or target. With more in-depth research, it is found that cell death pathways, carcinogenic signals, compensation feedback loop signal pathways and tumor immune microenvironment also play essential roles in the drug resistance mechanism. Here, we assess the current major mechanisms of CRC resistance and describe potential therapeutic interventions.

Chemokines and chemokine receptors in colorectal cancer; multifarious roles and clinical impact

Colorectal cancer (CRC) is considered the second cause of cancer death worldwide. The early diagnosis plays a key role in patient prognosis and subsequently overall survival. Similar to several types of cancer, colorectal cancer is also characterised by drug resistance and heterogeneity that contribute to its complexity -especially at advanced stages. However, despite the extensive research related to the identification of biomarkers associated to early diagnosis, accurate prognosis and the management of CRC patients, little progress has been made thus far. Therefore, the mortality rates, especially at advanced stages, remain high. A large family of chemoattractant cytokines called chemokines are known for their significant role in inflammation and immunity. Chemokines released by the different tumorous cells play a key role in increasing the complexity of the tumour's microenvironment. The current review investigates the role of chemokines and chemokine receptors in colorectal cancer and their potential as clinical molecular signatures that could be effectively used as a personalised therapeutic approach. We discussed how chemokine and chemokine receptors regulate the microenvironment and lead to heterogeneity in CRC. An important aspect of chemokines is their role in drug resistance which has been extensively discussed. This review also provides an overview of the current advances in the search for chemokines and chemokine receptors in CRC.

Regulatory role of the transforming growth factor-β signaling pathway in the drug resistance of gastrointestinal cancers

Gastrointestinal (GI) cancer, including esophageal, gastric, and colorectal cancer, is one of the most prevalent types of malignant carcinoma and the leading cause of cancer-related deaths. Despite significant advances in therapeutic strategies for GI cancers in recent decades, drug resistance with various mechanisms remains the prevailing cause of therapy failure in GI cancers. Accumulating evidence has demonstrated that the transforming growth factor (TGF)-β signaling pathway has crucial, complex roles in many cellular functions related to drug resistance. This review summarizes current knowledge regarding the role of the TGF-β signaling pathway in the resistance of GI cancers to conventional chemotherapy, targeted therapy, immunotherapy, and traditional medicine. Various processes, including epithelial-mesenchymal transition, cancer stem cell development, tumor microenvironment alteration, and microRNA biogenesis, are proposed as the main mechanisms of TGF-β-mediated drug resistance in GI cancers. Several studies have already indicated the benefit of combining antitumor drugs with agents that suppress the TGF-β signaling pathway, but this approach needs to be verified in additional clinical studies. Moreover, the identification of potential biological markers that can be used to predict the response to TGF-β signaling pathway inhibitors during anticancer treatments will have important clinical implications in the future.

The Versatile Roles of Cancer-Associated Fibroblasts in Colorectal Cancer and Therapeutic Implications

The tumor microenvironment (TME) is populated by abundant cancer-associated fibroblasts (CAFs) that radically influence the disease progression across many cancers, including the colorectal cancer (CRC). In theory, targeting CAFs holds great potential in optimizing CRC treatment. However, attempts to translate the therapeutic benefit of CAFs into clinic practice face many obstacles, largely due to our limited understanding of the heterogeneity in their origins, functions, and mechanisms. In recent years, accumulating evidence has uncovered some cellular precursors and molecular markers of CAFs and also revealed their versatility in impacting various hallmarks of CRC, together helping us to better define the population of CAFs and also paving the way toward their future therapeutic targeting for CRC treatment. In this review, we outline the emerging concept of CAFs in CRC, with an emphasis on their origins, biomarkers, prognostic significance, as well as their functional roles and underlying mechanisms in CRC biology. At last, we discuss the prospect of harnessing CAFs as promising therapeutic targets for the treatment of patients with CRC.

The Role of Tumor-Stroma Interactions in Drug Resistance Within Tumor Microenvironment

Cancer cells resistance to various therapies remains to be a key challenge nowadays. For a long time, scientists focused on tumor cells themselves for the mechanisms of acquired drug resistance. However, recent evidence showed that tumor microenvironment (TME) is essential for regulating immune escape, drug resistance, progression and metastasis of malignant cells. Reciprocal interactions between cancer cells and non-malignant cells within this milieu often reshape the TME and promote drug resistance. Therefore, advanced knowledge about these sophisticated interactions is significant for the design of effective therapeutic approaches. In this review, we highlight cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), T-regulatory lymphocytes (Tregs), mesenchymal stem cells (MSCs), cancer-associated adipocytes (CAAs), and tumor endothelial cells (TECs) existing in TME, as well as their multiple cross-talk with tumor cells, which eventually endows tumor cells with therapeutic resistance.

Development of Anti-Mouse CC Chemokine Receptor 8 Monoclonal Antibodies for Flow Cytometry

CC chemokine receptor 8 (CCR8) belongs to the class A of G protein-coupled receptor. It is highly expressed on Treg and T helper 2 (T_H2) cells recruited to the inflammation site and is implicated in allergy and asthma. Recently, CCR8+Treg cells have been suggested to be a master regulator in the immunosuppressive tumor microenvironment; therefore, developing sensitive monoclonal antibodies (mAbs) for CCR8 has been desired. This study established a specific and sensitive mAb for mouse CCR8 (mCCR8), which is useful for flow cytometry by using the Cell-Based Immunization and Screening (CBIS) method. The established anti-mCCR8 mAb, C₈Mab-2 (rat IgG_2b, kappa), reacted with mCCR8-overexpressed Chinese hamster ovary-K1 (CHO/mCCR8) cells and P388 (mouse lymphoid neoplasma) or J774-1 (mouse macrophage-like) cells, which express endogenous mCCR8 by flow cytometry. C₈Mab-2, which was established by the CBIS method, could be useful for elucidating the mCCR8-related biological response by flow cytometry.

Research advances of secretory proteins in malignant tumors

Secretory proteins in tumor tissues are important components of the tumor microenvironment. Secretory proteins act on tumor cells or stromal cells or mediate interactions between tumor cells and stromal cells, thereby affecting tumor progression and clinical treatment efficacy. In this paper, recent research advances in secretory proteins in malignant tumors are reviewed.

Chemokine (C-C Motif) Ligand 1 Derived from Tumor-Associated Macrophages Contributes to Esophageal Squamous Cell Carcinoma Progression via CCR8-Mediated Akt/Proline-Rich Akt Substrate of 40 kDa/Mammalian Target of Rapamycin Pathway

Tumor-associated macrophages (TAMs) promote tumor progression. The number of infiltrating TAMs is associated with poor prognosis in esophageal squamous cell carcinoma (ESCC) patients; however, the mechanism underlying this phenomenon is unclear. cDNA microarray analysis indicates that the expression of chemokine (C-C motif) ligand 1 (CCL1) is up-regulated in peripheral blood monocyte-derived macrophages stimulated using conditioned media from ESCC cells (TAM-like macrophages). Here, we evaluated the role of CCL1 in ESCC progression. CCL1 was overexpressed in TAM-like macrophages, and CCR8, a CCL1 receptor, was expressed on ESCC cell surface. TAM-like macrophages significantly enhanced the motility of ESCC cells, and neutralizing antibodies against CCL1 or CCR8 suppressed this increased motility. Recombinant human CCL1 promoted ESCC cell motility via the Akt/proline-rich Akt substrate of 40 kDa/mammalian target of rapamycin pathway. Phosphatidylinositol 3-kinase or Akt inhibitors, CCR8 silencing, and neutralizing antibody against CCR8 could significantly suppress these effects. The overexpression of CCL1 in stromal cells or CCR8 in ESCC cells was significantly associated with poor overall survival (P = 0.002 or P = 0.009, respectively) and disease-free survival (P = 0.009 or P = 0.047, respectively) in patients with ESCC. These results indicate that the interaction between stromal CCL1 and CCR8 on cancer cells promotes ESCC progression via the Akt/proline-rich Akt substrate of 40 kDa/mammalian target of rapamycin pathway, thereby providing novel therapeutic targets.

Taxanes in cancer treatment: Activity, chemoresistance and its overcoming

Since 1984, when paclitaxel was approved by the FDA for the treatment of advanced ovarian carcinoma, taxanes have been widely used as microtubule-targeting antitumor agents. However, their historic classification as antimitotics does not describe all their functions. Indeed, taxanes act in a complex manner, altering multiple cellular oncogenic processes including mitosis, angiogenesis, apoptosis, inflammatory response, and ROS production. On the one hand, identification of the diverse effects of taxanes on oncogenic signaling pathways provides opportunities to apply these cytotoxic drugs in a more rational manner. On the other hand, this may facilitate the development of novel treatment modalities to surmount anticancer drug resistance. In the latter respect, chemoresistance remains a major impediment which limits the efficacy of antitumor chemotherapy. Taxanes have shown impact on key molecular mechanisms including disruption of mitotic spindle, mitosis slippage and inhibition of angiogenesis. Furthermore, there is an emerging contribution of cellular processes including autophagy, oxidative stress, epigenetic alterations and microRNAs deregulation to the acquisition of taxane resistance. Hence, these two lines of findings are currently promoting a more rational and efficacious taxane application as well as development of novel molecular strategies to enhance the efficacy of taxane-based cancer treatment while overcoming drug resistance. This review provides a general and comprehensive picture on the use of taxanes in cancer treatment. In particular, we describe the history of application of taxanes in anticancer therapeutics, the synthesis of the different drugs belonging to this class of cytotoxic compounds, their features and the differences between them. We further dissect the molecular mechanisms of action of taxanes and the molecular basis underlying the onset of taxane resistance. We further delineate the possible modalities to overcome chemoresistance to taxanes, such as increasing drug solubility, delivery and pharmacokinetics, overcoming microtubule alterations or mitotic slippage, inhibiting drug efflux pumps or drug metabolism, targeting redox metabolism, immune response, and other cellular functions.

Human Adipose-Derived Mesenchymal Stem Cells-Derived Exosomal microRNA-19b Promotes the Healing of Skin Wounds Through Modulation of the CCL1/TGF-β Signaling Axis

Introduction

Human adipose-derived mesenchymal stem cells (ADMSCs) with their secretory factors are able to induce collagen synthesis and fibroblast migration in the wound healing process. This study is launched to figure out the effect of human ADMSCs-derived exosomes on skin wound healing.

Methods

ADMSCs were extracted and ADMSCs-derived exosomes were identified. Skin damage models were established by treating HaCaT cells and human skin fibroblasts with H₂O₂. Next, the roles of ADMSCs and their derived exosomes were investigated. The exosomal miRNA then was analyzed, and the function of miRNA on the H₂O₂-induced cells was studied by miRNA suppression. Bioinformatics analysis, luciferase activity and RIP assays were implemented to find the target genes ofthe miRNA and the modulated pathways. A mouse skin damage model was induced to elucidate the effects of exosomes in vivo by injecting exosomes.

Results

H₂O₂ treatment significantly reduced the viability of HaCaT cells and increased their apoptosis rate. Co-culture with ADMSCs or their derived exosomes could improve the cell damage caused by H₂O₂. Meanwhile, H₂O₂ treatment promoted the internalization of exosomes. ADMSCs and their derived exosomes significantly increased miR-19b expression in the recipient cells, while inhibiting miR-19b resulted in a reduction in the therapeutic effect of ADMSCs-derived exosomes. Besides, miR-19b regulated the TGF-β pathway by targeting CCL1. The therapeutic effect of exosomes was further confirmed by a mouse model of skin damage.

Conclusion

Our study indicates that exosomal miR-19b derived from ADMSCs regulates the TGF-β pathway by targeting CCL1, thereby promoting the healing of skin wounds.

CC Chemokines in a Tumor: A Review of Pro-Cancer and Anti-Cancer Properties of Receptors CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10 Ligands

CC chemokines (or β-chemokines) are 28 chemotactic cytokines with an N-terminal CC domain that play an important role in immune system cells, such as CD4⁺ and CD8⁺ lymphocytes, dendritic cells, eosinophils, macrophages, monocytes, and NK cells, as well in neoplasia. In this review, we discuss human CC motif chemokine ligands: CCL1, CCL3, CCL4, CCL5, CCL18, CCL19, CCL20, CCL21, CCL25, CCL27, and CCL28 (CC motif chemokine receptor CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10 ligands). We present their functioning in human physiology and in neoplasia, including their role in the proliferation, apoptosis resistance, drug resistance, migration, and invasion of cancer cells. We discuss the significance of chemokine receptors in organ-specific metastasis, as well as the influence of each chemokine on the recruitment of various cells to the tumor niche, such as cancer-associated fibroblasts (CAF), Kupffer cells, myeloid-derived suppressor cells (MDSC), osteoclasts, tumor-associated macrophages (TAM), tumor-infiltrating lymphocytes (TIL), and regulatory T cells (T_reg). Finally, we show how the effect of the chemokines on vascular endothelial cells and lymphatic endothelial cells leads to angiogenesis and lymphangiogenesis.

Cellular Mechanisms Accounting for the Refractoriness of Colorectal Carcinoma to Pharmacological Treatment

Simple Summary

Colorectal cancer (CRC) causes a high number (more than 800,000) of deaths worldwide each year. Better methods for early diagnosis and the development of strategies to enhance the efficacy of the therapeutic approaches used to complement or substitute surgical removal of the tumor are urgently needed. Currently available pharmacological armamentarium provides very moderate benefits to patients due to the high resistance of tumor cells to respond to anticancer drugs. The present review summarizes and classifies into seven groups the cellular and molecular mechanisms of chemoresistance (MOC) accounting for the failure of CRC response to the pharmacological treatment.

Abstract

The unsatisfactory response of colorectal cancer (CRC) to pharmacological treatment contributes to the substantial global health burden caused by this disease. Over the last few decades, CRC has become the cause of more than 800,000 deaths per year. The reason is a combination of two factors: (i) the late cancer detection, which is being partially solved by the implementation of mass screening of adults over age 50, permitting earlier diagnosis and treatment; (ii) the inadequate response of advanced unresectable tumors (i.e., stages III and IV) to pharmacological therapy. The latter is due to the existence of complex mechanisms of chemoresistance (MOCs) that interact and synergize with each other, rendering CRC cells strongly refractory to the available pharmacological regimens based on conventional chemotherapy, such as pyrimidine analogs (5-fluorouracil, capecitabine, trifluridine, and tipiracil), oxaliplatin, and irinotecan, as well as drugs targeted toward tyrosine kinase receptors (regorafenib, aflibercept, bevacizumab, cetuximab, panitumumab, and ramucirumab), and, more recently, immune checkpoint inhibitors (nivolumab, ipilimumab, and pembrolizumab). In the present review, we have inventoried the genes involved in the lack of CRC response to pharmacological treatment, classifying them into seven groups (from MOC-1 to MOC-7) according to functional criteria to identify cancer cell weaknesses. This classification will be useful to pave the way for developing sensitizing tools consisting of (i) new agents to be co-administered with the active drug; (ii) pharmacological approaches, such as drug encapsulation (e.g., into labeled liposomes or exosomes); (iii) gene therapy interventions aimed at restoring the impaired function of some proteins (e.g., uptake transporters and tumor suppressors) or abolishing that of others (such as export pumps and oncogenes).

5-Fluorouracil resistance mechanisms in colorectal cancer: From classical pathways to promising processes

Colorectal cancer (CRC) is a public health problem. It is the third most common cancer in the world, with nearly 1.8 million new cases diagnosed in 2018. The only curative treatment is surgery, especially for early tumor stages. When there is locoregional or distant invasion, chemotherapy can be introduced, in particular 5-fluorouracil (5-FU). However, the disease can become tolerant to these pharmaceutical treatments: resistance emerges, leading to early tumor recurrence. Different mechanisms can explain this 5-FU resistance. Some are disease-specific, whereas others, such as drug efflux, are evolutionarily conserved. These mechanisms are numerous and complex and can occur simultaneously in cells exposed to 5-FU. In this review, we construct a global outline of different mechanisms from disruption of 5-FU-metabolic enzymes and classic cellular processes (apoptosis, autophagy, glucose metabolism, oxidative stress, respiration, and cell cycle perturbation) to drug transporters and epithelial-mesenchymal transition induction. Particular interest is directed to tumor microenvironment function as well as epigenetic alterations and miRNA dysregulation, which are the more promising processes that will be the subject of much research in the future.

Hypoxia Alters the Expression of CC Chemokines and CC Chemokine Receptors in a Tumor-A Literature Review

Hypoxia, i.e., oxygen deficiency condition, is one of the most important factors promoting the growth of tumors. Since its effect on the chemokine system is crucial in understanding the changes in the recruitment of cells to a tumor niche, in this review we have gathered all the available data about the impact of hypoxia on β chemokines. In the introduction, we present the chronic (continuous, non-interrupted) and cycling (intermittent, transient) hypoxia together with the mechanisms of activation of hypoxia inducible factors (HIF-1 and HIF-2) and NF-κB. Then we describe the effect of hypoxia on the expression of chemokines with the CC motif: CCL1, CCL2, CCL3, CCL4, CCL5, CCL7, CCL8, CCL11, CCL13, CCL15, CCL16, CCL17, CCL18, CCL19, CCL20, CCL21, CCL22, CCL24, CCL25, CCL26, CCL27, CCL28 together with CC chemokine receptors: CCR1, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10. To better understand the effect of hypoxia on neoplastic processes and changes in the expression of the described proteins, we summarize the available data in a table which shows the effect of individual chemokines on angiogenesis, lymphangiogenesis, and recruitment of eosinophils, myeloid-derived suppressor cells (MDSC), regulatory T cells (T_reg), and tumor-associated macrophages (TAM) to a tumor niche.

Tumor microenvironment and epithelial mesenchymal transition as targets to overcome tumor multidrug resistance

It is well established that multifactorial drug resistance hinders successful cancer treatment. Tumor cell interactions with the tumor microenvironment (TME) are crucial in epithelial-mesenchymal transition (EMT) and multidrug resistance (MDR). TME-induced factors secreted by cancer cells and cancer-associated fibroblasts (CAFs) create an inflammatory microenvironment by recruiting immune cells. CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSCs) and inflammatory tumor associated macrophages (TAMs) are main immune cell types which further enhance chronic inflammation. Chronic inflammation nurtures tumor-initiating/cancer stem-like cells (CSCs), induces both EMT and MDR leading to tumor relapses. Pro-thrombotic microenvironment created by inflammatory cytokines and chemokines from TAMs, MDSCs and CAFs is also involved in EMT and MDR. MDSCs are the most common mediators of immunosuppression and are also involved in resistance to targeted therapies, e.g. BRAF inhibitors and oncolytic viruses-based therapies. Expansion of both cancer and stroma cells causes hypoxia by hypoxia-inducible transcription factors (e.g. HIF-1α) resulting in drug resistance. TME factors induce the expression of transcriptional EMT factors, MDR and metabolic adaptation of cancer cells. Promoters of several ATP-binding cassette (ABC) transporter genes contain binding sites for canonical EMT transcription factors, e.g. ZEB, TWIST and SNAIL. Changes in glycolysis, oxidative phosphorylation and autophagy during EMT also promote MDR. Conclusively, EMT signaling simultaneously increases MDR. Owing to the multifactorial nature of MDR, targeting one mechanism seems to be non-sufficient to overcome resistance. Targeting inflammatory processes by immune modulatory compounds such as mTOR inhibitors, demethylating agents, low-dosed histone deacetylase inhibitors may decrease MDR. Targeting EMT and metabolic adaptation by small molecular inhibitors might also reverse MDR. In this review, we summarize evidence for TME components as causative factors of EMT and anticancer drug resistance.

The Gastrointestinal Tumor Microenvironment: An Updated Biological and Clinical Perspective

Gastrointestinal cancers are still responsible for high numbers of cancer-related deaths despite advances in therapy. Tumor-associated cells play a key role in tumor biology, by supporting or halting tumor development through the production of extracellular matrix, growth factors, cytokines, and extracellular vesicles. Here, we review the roles of these tumor-associated cells in the initiation, angiogenesis, immune modulation, and resistance to therapy of gastrointestinal cancers. We also discuss novel diagnostic and therapeutic strategies directed at tumor-associated cells and their potential benefits for the survival of these patients.

Guanylate-binding protein-2 inhibits colorectal cancer cell growth and increases the sensitivity to paclitaxel of paclitaxel-resistant colorectal cancer cells by interfering Wnt signaling

Among the GTPase family members, guanylate-binding protein-1 (GBP-1) is the most thoroughly studied member in a plethora of human cancers. GBP-2, on the other hand, remains limitedly studied. We wonder how GBP-2 participates in colorectal carcinoma (CRC) as well as the paclitaxel (PTX)-resistance of CRC. In this study, the authors are determined to dig into the role that GBP-2 plays in the sensitivity of CRC to PTX, therefore, possibly indicating a promising gene therapy target for CRC. Forced expression of GBP-2 gene was done by plasmid transfection. Reverse transcriptase-polymerase chain reaction and immunoblot were conducted to detect the expression of GBP-2 messenger RNA (mRNA) and protein, respectively. Colony foci formation assay, transwell invasion assay, and flow cytofluorometry were done to determine the proliferation, invasion, and apoptosis of PTX-resistant and PTX-sensitive CRC cell lines, respectively. The level of GBP-2 mRNA and protein in PTX-resistant CRC cell lines was significantly lower than in nonresistant cell lines. Forced exogenous expression of GBP-2 in PTX-resistant CRC cell lines resulted in more sensitivity to PTX because of the demonstration of less cell proliferation, invasion, and more apoptosis. Wnt signaling was suppressed when GBP-2 was upregulated by transfection of GBP-2 overexpression plasmids, and Wnt signaling did not affect GBP-2 expression. GBP-2 upregulation could enhance the killing effect of PTX in both PTX-sensitive CRC cells and PTX-resistant CRC cells by suppressing Wnt signaling.

Nodal Facilitates Differentiation of Fibroblasts to Cancer-Associated Fibroblasts that Support Tumor Growth in Melanoma and Colorectal Cancer

Fibroblasts become cancer-associated fibroblasts (CAFs) in the tumor microenvironment after activation by transforming growth factor-β (TGF-β) and are critically involved in cancer progression. However, it is unknown whether the TGF superfamily member Nodal, which is expressed in various tumors but not expressed in normal adult tissue, influences the fibroblast to CAF conversion. Here, we report that Nodal has a positive correlation with α-smooth muscle actin (α-SMA) in clinical melanoma and colorectal cancer (CRC) tissues. We show the Nodal converts normal fibroblasts to CAFs, together with Snail and TGF-β signaling pathway activation in fibroblasts. Activated CAFs promote cancer growth in vitro and tumor-bearing mouse models in vivo. These results demonstrate that intercellular crosstalk between cancer cells and fibroblasts is mediated by Nodal, which controls tumor growth, providing potential targets for the prevention and treatment of tumors.

Cancer-associated fibroblasts promote PD-L1 expression in mice cancer cells via secreting CXCL5

Cancer-associated fibroblasts (CAFs) play a key role in orchestrating the tumor malignant biological properties within tumor microenvironment and evidences demonstrate that CAFs are a critical regulator of tumoral immunosuppression of the T cell response. However, the functions and regulation of CAFs in the expression of programmed death-ligand 1 (PD-L1) in melanoma and colorectal carcinoma (CRC) are not completely understood. Herein, by scrutinizing the expression of α-SMA and PD-L1 in melanoma and CRC tissues, we found that CAFs was positive correlated with PD-L1 expression. Further analyses showed that CAFs promoted PD-L1 expression in mice tumor cells. By detecting a majority of cytokines expression in normal mice fibroblasts and CAFs, we determined that CXCL5 was abnormal high expression in CAFs and the immunohistochemistry and in situ hybridization confirmed that were CAFs which were expressing CXCL5. In addition, CXCL5 promoted PD-L1 expression in B16, CT26, A375 and HCT116. The silencing of CXCR2, the receptor of CXCL5, inhibited the PD-L1 expression induced by CAFs in turn. Functionally, CXCL5 derived by CAFs promoted PD-L1 expression in mice tumor cells through activating PI3K/AKT signaling. LY294002, the inhibitor of PI3K, confirmed that CXCL5 forested an immunosuppression microenvironment by promoting PD-L1 expression via PI3K/AKT signaling. Meanwhile, the B16/CT26 xenograft tumor models were used and both CXCR2 and p-AKT were found to be positively correlated with PD-L1 in the xenograft tumor tissues. The immunosuppressive action of CAFs on tumor cells is probably reflective of them being a potential therapeutic biomarker for melanoma and CRC.

High expression of Snail1 is associated with EMAST and poor prognosis in CRC patients

AIM

This study aimed to determine the link between Snail1 expression and CRC patients' survival as well as its significant association with EMAST status.

BACKGROUND

Snail1 is an evolutionary preserved zinc-finger transcription protein which contributes to Epithelial-to-mesenchymal transition (EMT). EMT initiates invasion and proliferation in many tumors. Elevated microsatellite alteration at selected tetranucleotide repeats (EMAST) is a marker of poor prognosis in patients with colorectal cancer (CRC). We hypothesized that Snail1 overexpression is an important mediator of metastasis and decreased survival in CRCs that characteristically have EMAST phenotype.

METHODS

Quantitative real-time polymerase chain reactions were carried out to analyze the expression levels of Snail1 in both normal and tumor specimens from a total of 122 paraffin-embedded tissues (FFPE) of CRC sample with known EMAST status. The correlation between Snail1 expression and clinicopathological characteristics, survival, and EMAST status were examined.

RESULTS

Snail1 overexpression was detected in tumor tissues in 32% of all examined patients and its positive expression was related to metastasis (p=0.001) and EMAST+ phenotype (P=0.017). Further, positive Snail1 expression correlates with poor overall survival in CRC patients (P=0.01).

CONCLUSION

Our findings suggest that Snail1 overexpression is not only associated with EMAST but also with clinicopathological variables of poor prognosis. These results indicate that Snail1 expression levels may be useful for establishing novel therapeutic strategies and could help survival improvement in CRC patients.

Chemoresistance of Cancer Cells: Requirements of Tumor Microenvironment-mimicking In Vitro Models in Anti-Cancer Drug Development

For decades, scientists have been using two-dimensional cell culture platforms for high-throughput drug screening of anticancer drugs. Growing evidence indicates that the results of anti-cancer drug screening vary with the cell culture microenvironment, and this variation has been proposed as a reason for the high failure rate of clinical trials. Since the culture condition-dependent drug sensitivity of anti-cancer drugs may negatively impact the identification of clinically effective drug candidates, more reliable in vitro cancer platforms are urgently needed. In this review article, we provide an overview of how cell culture conditions can alter drug efficacy and highlight the importance of developing more reliable cancer drug testing platforms for use in the drug discovery process. The environmental factors that can alter drug delivery and efficacy are reviewed. Based on these observations of chemoresistant tumor physiology, we summarize the recent advances in the fabrication of in vitro cancer models and the model-dependent cytotoxicity of anti-cancer drugs, with a particular focus on engineered environmental factors in these platforms. It is believed that more physiologically relevant cancer models can revolutionize the drug discovery process.