The disparate twins: a comparative study of CXCR4 and CXCR7 in SDF-1α-induced gene expression, invasion and chemosensitivity of colon cancer

AXL receptor as an emerging molecular target in colorectal cancer

AXL receptor tyrosine kinase (AXL) is a receptor tyrosine kinase whose aberrant expression has recently been associated with colorectal cancer (CRC), contributing to tumor growth, epithelial-mesenchymal transition (EMT), increased invasiveness, metastatic spreading, and the development of drug resistance. In this review we summarize preclinical data, the majority of which are limited to recent years, convincingly linking the AXL receptor to CRC. These findings support the value of targeting AXL with molecules in drug discovery, offering novel and advanced therapeutic or diagnostic tools for CRC management.

Evaluation of C-X-C chemokine receptor type 4 (CXCR4) and Peroxisome proliferator-activated receptor gamma (PPAR-γ) expression in colorectal carcinoma: Relation to the available clinicopathological parameters

Background

Colorectal carcinoma (CRC) is the most common malignancy of the gastrointestinal tract, representing an incredible health problem. It is essential to develop drugs against novel targets--involved in CRC tumorigenesis and progression--to improve the management of the disease. The aim of this study was to evaluate C-X-C chemokine receptor type 4 (CXCR4) and Peroxisome proliferator-activated receptor gamma (PPAR-γ) expression in CRC, and to associate their expression with the available clinicopathological parameters.

Materials and Methods

This study included 50 cases of primary CRC. All cases were stained by CXCR4 and PPAR-γ antibodies to assess their immunohistochemical expression. The relations between their expression and clinicopathological variables were assessed.

Results

CXCR4 expression was detected in 76% of studied cases. High CXCR4 expression showed significant associations with the depth of tumor invasion (P = 0.024), lymph node metastasis (P = 0.009), advanced tumor stage (P = 0.001) and the presence of vascular invasion (P = 0.035). PPAR-γ expression was detected in 78% of studied cases. PPAR-γ expression showed a statistically significant inverse relation with histologic types (P = 0.001), tumor grade (P = 0.005), depth of tumor invasion (P = 0.001), lymph node status (P = 0.001), TNM stage (P = 0.002), and vascular invasion (P = 0.001).

Conclusions

High CXCR4 and decreased PPAR-γ expressions are related to high tumor grade, advanced stage, and vascular invasion in colorectal carcinoma.

Reverse tracking from drug-induced transcriptomes through multilayer molecular networks reveals hidden drug targets

Identifying molecular targets of a drug is an essential process for drug discovery and development. The recent in-silico approaches are usually based on the structure information of chemicals and proteins. However, 3D structure information is hard to obtain and machine-learning methods using 2D structure suffer from data imbalance problem. Here, we present a reverse tracking method from genes to target proteins using drug-perturbed gene transcriptional profiles and multilayer molecular networks. We scored how well the protein explains gene expression changes perturbed by a drug. We validated the protein scores of our method in predicting known targets of drugs. Our method performs better than other methods using the gene transcriptional profiles and shows the ability to suggest the molecular mechanism of drugs. Furthermore, our method has the potential to predict targets for objects that do not have rigid structural information, such as coronavirus.

Recruitment mechanisms and therapeutic implications of tumor-associated macrophages in the glioma microenvironment

As one of the main components of the glioma immune microenvironment, glioma-associated macrophages (GAMs) have increasingly drawn research interest. Primarily comprised of resident microglias and peripherally derived mononuclear macrophages, GAMs are influential in a variety of activities such as tumor cell resistance to chemotherapy and radiotherapy as well as facilitation of glioma pathogenesis. In addition to in-depth research of GAM polarization, study of mechanisms relevant in tumor microenvironment recruitment has gradually increased. Suppression of GAMs at their source is likely to produce superior therapeutic outcomes. Here, we summarize the origin and recruitment mechanism of GAMs, as well as the therapeutic implications of GAM inhibition, to facilitate future glioma-related research and formulation of more effective treatment strategies.

Colorectal Cancer: The Contribution of CXCL12 and Its Receptors CXCR4 and CXCR7

Colorectal cancer is one of the most common cancers, and diagnosis at late metastatic stages is the main cause of death related to this cancer. This progression to metastasis is complex and involves different molecules such as the chemokine CXCL12 and its two receptors CXCR4 and CXCR7. The high expression of receptors in CRC is often associated with a poor prognosis and aggressiveness of the tumor. The interaction of CXCL12 and its receptors activates signaling pathways that induce chemotaxis, proliferation, migration, and cell invasion. To this end, receptor inhibitors were developed, and their use in preclinical and clinical studies is ongoing. This review provides an overview of studies involving CXCR4 and CXCR7 in CRC with an update on their targeting in anti-cancer therapies.

Anti-Axl monoclonal antibodies attenuate the migration of MDA-MB-231 breast cancer cells

The receptor tyrosine kinase, anexelekto (Axl) is involved in tumor cell growth, migration and invasion, and has been associated with chemotherapy resistance, which makes it an attractive target for cancer therapy. In total, six Axl-targeted monoclonal antibodies (mAbs) and two antibody-drug conjugates have been reported in the last 10 years, which have been shown to have bioactivity in inhibiting tumor cell proliferation and migration. The Axl external cell domain (Axl^−ECD), consisting of 426 amino acids, has always been used as an antigen in the screening process for all six of these Axl-targeted mAbs. However, the Axl functional domain, which interacts with its natural ligand, growth arrest-specific protein 6 (Gas6), is only a small part of the Axl^−ECD. Antibodies targeting the Axl functional domain may efficiently block Gas6-Axl binding and attenuate its downstream signals and activities. To the best of our knowledge, no mAbs targeting the Axl functional domain have been reported. In the present study, a major Axl functional domain interacting with Gas6 was determined using bioinformatics and structural biology methods. In MDA-MB-231 breast cancer cell assays, anti-Axl mAbs targeting this relatively specific Axl functional domain almost completely neutralized the stimulation of Gas6 in both Axl phosphorylation and cell migration assays, and showed similar activity to the positive control drug R428 (a small molecular tyrosine kinase inhibitor of Axl currently in phase II clinical trials) in the cell migration assay. Given the important role of Axl in tumor development and chemotherapy resistance, Axl-targeted mAbs could be used to inhibit tumor cells directly, as well as reduce the development of chemotherapy resistance by blocking Axl activity. The application of Axl-targeted mAbs combined with chemotherapy provides a promising treatment strategy for patients with tumors, particularly those with triple-negative breast cancer, for whom no targeted therapy is currently available.

Long Non-Coding RNA Myosin Light Chain Kinase Antisense 1 Plays an Oncogenic Role in Gallbladder Carcinoma by Promoting Chemoresistance and Proliferation

Background

Long non-coding RNAs (lncRNAs) have been reported to play critical roles in human tumours, including gallbladder carcinoma (GBC). However, their biological functions and molecular mechanisms in tumorigenesis and progression remain largely unknown.

Methods

Quantitative polymerase chain reaction (qPCR) was used to verify the expression of lncRNA myosin light chain kinase antisense RNA 1 (MYLK-AS1) in 120 pairs of GBC tissues and paired adjacent non-tumour tissues, as well as in six different GBC cell lines (NOZ, EH-GB1, OCUG-1, GBC-SD, SGC-996 and QBC-939). Cell counting kit 8 was applied to explore cell proliferation and drug sensitivity assays. The target miRNAs (miR) of MYLK-AS1 and downstream target genes were predicted using Starbase 3.0 software and confirmed by double luciferase reporting test. The expression of proteins was assessed using Western blot assay.

Results

Here, we demonstrated that MYLK-AS1 was significantly upregulated and correlated with a poor prognosis and poor clinical characteristics in GBC. Furthermore, the forced expression of MYLK-AS1 significantly promoted GBC cell proliferation and resistance to gemcitabine in vitro. Mechanistically, MYLK-AS1 functioned as an efficient miR-217 sponge, thereby releasing the inhibition of enhancer of zeste 2 polycomb repressive complex 2 (EZH2) subunit expression. MYLK-AS1 promoted GBC cell proliferation and resistance to gemcitabine by upregulating EZH2 expression, and EZH2 was confirmed as a direct target of miR-217.

Discussion

Our results confirmed that the chemoresistant driver MYLK-AS1 might be a promising candidate as a therapeutic target for the treatment of advanced GBC.

CXCL12-CXCR4/CXCR7 Axis in Colorectal Cancer: Therapeutic Target in Preclinical and Clinical Studies

Chemokines are chemotactic cytokines that promote cancer growth, metastasis, and regulate resistance to chemotherapy. Stromal cell-derived factor 1 (SDF1) also known as C-X-C motif chemokine 12 (CXCL12), a prognostic factor, is an extracellular homeostatic chemokine that is the natural ligand for chemokine receptors C-X-C chemokine receptor type 4 (CXCR4), also known as fusin or cluster of differentiation 184 (CD184) and chemokine receptor type 7 (CXCR7). CXCR4 is the most widely expressed rhodopsin-like G protein coupled chemokine receptor (GPCR). The CXCL12-CXCR4 axis is involved in tumor growth, invasion, angiogenesis, and metastasis in colorectal cancer (CRC). CXCR7, recently termed as atypical chemokine receptor 3 (ACKR3), is amongst the G protein coupled cell surface receptor family that is also commonly expressed in a large variety of cancer cells. CXCR7, like CXCR4, regulates immunity, angiogenesis, stem cell trafficking, cell growth and organ-specific metastases. CXCR4 and CXCR7 are expressed individually or together, depending on the tumor type. When expressed together, CXCR4 and CXCR7 can form homo- or hetero-dimers. Homo- and hetero-dimerization of CXCL12 and its receptors CXCR4 and CXCR7 alter their signaling activity. Only few drugs have been approved for clinical use targeting CXCL12-CXCR4/CXCR7 axis. Several CXCR4 inhibitors are in clinical trials for solid tumor treatment with limited success whereas CXCR7-specific inhibitors are still in preclinical studies for CRC. This review focuses on current knowledge of chemokine CXCL12 and its receptors CXCR4 and CXCR7, with emphasis on targeting the CXCL12-CXCR4/CXCR7 axis as a treatment strategy for CRC.

The CXCL12 Crossroads in Cancer Stem Cells and Their Niche

Simple Summary

CXCL12 and its receptors have been extensively studied in cancer, including their influence on cancer stem cells (CSCs) and their niche. This intensive research has led to a better understanding of the crosstalk between CXCL12 and CSCs, which has aided in designing several drugs that are currently being tested in clinical trials. However, a comprehensive review has not been published to date. The aim of this review is to provide an overview on how CXCL12 axes are involved in the regulation and maintenance of CSCs, their presence and influence at different cellular levels within the CSC niche, and the current state-of-the-art of therapeutic approaches aimed to target the CXCL12 crossroads.

Abstract

Cancer stem cells (CSCs) are defined as a subpopulation of “stem”-like cells within the tumor with unique characteristics that allow them to maintain tumor growth, escape standard anti-tumor therapies and drive subsequent repopulation of the tumor. This is the result of their intrinsic “stem”-like features and the strong driving influence of the CSC niche, a subcompartment within the tumor microenvironment that includes a diverse group of cells focused on maintaining and supporting the CSC. CXCL12 is a chemokine that plays a crucial role in hematopoietic stem cell support and has been extensively reported to be involved in several cancer-related processes. In this review, we will provide the latest evidence about the interactions between CSC niche-derived CXCL12 and its receptors—CXCR4 and CXCR7—present on CSC populations across different tumor entities. The interactions facilitated by CXCL12/CXCR4/CXCR7 axes seem to be strongly linked to CSC “stem”-like features, tumor progression, and metastasis promotion. Altogether, this suggests a role for CXCL12 and its receptors in the maintenance of CSCs and the components of their niche. Moreover, we will also provide an update of the therapeutic options being currently tested to disrupt the CXCL12 axes in order to target, directly or indirectly, the CSC subpopulation.

The Role of the CXCL12/CXCR4/CXCR7 Chemokine Axis in Cancer

Chemokines are a family of small, secreted cytokines which regulate a variety of cell functions. The C-X-C motif chemokine ligand 12 (CXCL12) binds to C-X-C chemokine receptor type 4 (CXCR4) and C-X-C chemokine receptor type 7 (CXCR7). The interaction of CXCL12 and its receptors subsequently induces downstream signaling pathways with broad effects on chemotaxis, cell proliferation, migration, and gene expression. Accumulating evidence suggests that the CXCL12/CXCR4/CXCR7 axis plays a pivotal role in tumor development, survival, angiogenesis, metastasis, and tumor microenvironment. In addition, this chemokine axis promotes chemoresistance in cancer therapy via complex crosstalk with other pathways. Multiple small molecules targeting CXCR4/CXCR7 have been developed and used for preclinical and clinical cancer treatment. In this review, we describe the roles of the CXCL12/CXCR4/CXCR7 axis in cancer progression and summarize strategies to develop novel targeted cancer therapies.

Functions and mechanisms of chemokine receptor 7 in tumors of the digestive system

Chemokine (C-X-C motif) receptor 7 (CXCR7), recently termed ACKR3, belongs to the G protein-coupled cell surface receptor family, binds to stromal cell-derived factor-1 [SDF-1, or chemokine (C-X-C motif) ligand 12] or chemokine (C-X-C motif) ligand 11, and is the most common chemokine receptor expressed in a variety of cancer cells. SDF-1 binds to its receptor chemokine (C-X-C motif) receptor 4 (CXCR4) and regulates cell proliferation, survival, angiogenesis and migration. In recent years, another new receptor for SDF-1, CXCR7, has been discovered, and CXCR7 has also been found to be expressed in a variety of tumor cells and tumor-related vascular endothelial cells. Many studies have shown that CXCR7 can promote the growth and metastasis of a variety of malignant tumor cells. Unlike CXCR4, CXCR7 exhibits a slight modification in the DRYLAIV motif and does not induce intracellular Ca²⁺ release following ligand binding, which is essential for recruiting and activating G proteins. CXCR7 is generally thought to work in three ways: (1) Recruiting β-arrestin 2; (2) Heterodimerizing with CXCR4; and (3) Acting as a “scavenger” of SDF-1, thus lowering the level of SDF-1 to weaken the activity of CXCR4. In the present review, the expression and role of CXCR7, as well as its prognosis in cancers of the digestive system, were investigated.

Correlation between FAK and EGF-Induced EMT in Colorectal Cancer Cells

Epithelial-mesenchymal transition (EMT) plays an important role in the invasion and metastasis of colorectal cancer, which is mediated by FAK and EGF. However, whether FAK participates in EMT in colorectal cancer cells through the EGF/EGFR signaling pathway remains unknown. The aim of this study was to investigate the effector mechanisms of FAK in the process of EGF-induced EMT in colorectal cancer cells and to determine whether miR-217 is involved in this process. Caco-2 cancer cells were routinely cultured with and without treatment with 100 ng/mL EGF, and changes in cell morphology were observed using an inverted microscope. In addition, a transwell assay was used to detect cell migration under the condition of EGF treatment. The expression of FAK, pFAK, E-cadherin, vimentin, and β actin was assessed by western blotting, and the expression of miR-217 was assessed using real-time PCR. We found that EGF induced EMT in colorectal cancer cells and enhanced cell migration and invasion ability. Moreover, FAK was involved in the EGF-induced EMT of colorectal cancer cells. EGF upregulated the expression of E-cadherin in colorectal cancer cells by activating FAK, and miR-217 was found to participate in EGF-induced EMT in colorectal cancer cells. Our findings indicate that EGF induces EMT in colorectal cancer cells by activating FAK, and miR-217 is involved in the EGF/FAK/E-cadherin signaling pathway.

The CXCL12-CXCR4/CXCR7 axis as a mechanism of immune resistance in gastrointestinal malignancies

Single agent checkpoint inhibitor therapy has not been effective for most gastrointestinal solid tumors, but combination therapy with drugs targeting additional immunosuppressive pathways is being attempted. One such pathway, the CXCL12-CXCR4/CXCR7 chemokine axis, has attracted attention due to its effects on tumor cell survival and metastasis as well as immune cell migration. CXCL12 is a small protein that functions in normal hematopoietic stem cell homing in addition to repair of damaged tissue. Binding of CXCL12 to CXCR4 leads to activation of G protein signaling kinases such as P13K/mTOR and MEK/ERK while binding to CXCR7 leads to β-arrestin mediated signaling. While some gastric and colorectal carcinoma cells have been shown to make CXCL12, the primary source in pancreatic cancer and peritoneal metastases is cancer-associated fibroblasts. Binding of CXCL12 to CXCR4 and CXCR7 on tumor cells leads to anti-apoptotic signaling through Bcl-2 and survivin upregulation, as well as promotion of the epithelial-to-mesechymal transition through the Rho-ROCK pathway and alterations in cell adhesion molecules. High levels of CXCL12 seen in the bone marrow, liver, and spleen could partially explain why these are popular sites of metastases for many tumors. CXCL12 is a chemoattractant for lymphocytes at lower levels, but becomes chemorepellant at higher levels; it is unclear exactly what gradient exists in the tumor microenvironment and how this influences tumor-infiltrating lymphocytes. AMD3100 (Plerixafor or Mozobil) is a small molecule CXCR4 antagonist and is the most frequently used drug targeting the CXCL12-CXCR4/CXCR7 axis in clinical trials for gastrointestinal solid tumors currently. Other small molecules and monoclonal antibodies against CXCR4 are being trialed. Further understanding of the CXCL12- CXCR4/CXCR7 chemokine axis in the tumor microenvironment will allow more effective targeting of this pathway in combination immunotherapy.

AXL receptor tyrosine kinase as a promising anti-cancer approach: functions, molecular mechanisms and clinical applications

Molecular targeted therapy for cancer has been a research hotspot for decades. AXL is a member of the TAM family with the high-affinity ligand growth arrest-specific protein 6 (GAS6). The Gas6/AXL signalling pathway is associated with tumour cell growth, metastasis, invasion, epithelial-mesenchymal transition (EMT), angiogenesis, drug resistance, immune regulation and stem cell maintenance. Different therapeutic agents targeting AXL have been developed, typically including small molecule inhibitors, monoclonal antibodies (mAbs), nucleotide aptamers, soluble receptors, and several natural compounds. In this review, we first provide a comprehensive discussion of the structure, function, regulation, and signalling pathways of AXL. Then, we highlight recent strategies for targeting AXL in the treatment of cancer.AXL-targeted drugs, either as single agents or in combination with conventional chemotherapy or other small molecule inhibitors, are likely to improve the survival of many patients. However, future investigations into AXL molecular signalling networks and robust predictive biomarkers are warranted to select patients who could receive clinical benefit and to avoid potential toxicities.

CXCR4 mutations affect presentation and outcomes in patients with Waldenström macroglobulinemia: A systematic review

Introduction: The genomic landscape of Waldenström macroglobulinemia (WM) is characterized by recurrent MYD88 (MYD88^L265P) and CXCR4 mutations (CXCR4^MUT), detected in 90% and 30% of cases, respectively. The role of CXCR4^MUT in clinical features and outcomes to therapy in WM patients is evolving. Areas covered: We performed a systematic review aimed at evaluating the prevalence of CXCR4^MUT in WM patients, and at assessing differences in clinical features and outcomes to therapy between WM patients with and without CXCR4^MUT. Seventeen studies were included in our analysis. The pooled prevalence of CXCR4^MUT in WM patients was 31%; 34% in MYD88^L265P and 5% in MYD88^WT patients. CXCR4^MUT were associated with higher serum IgM levels and higher risk of hyperviscosity than CXCR4^WT patients. Very good partial response (VGPR) and progression-free survival (PFS) rates to ibrutinib, with and without rituximab, appeared lower in CXCR4^MUT than in CXCR4^WT patients. Response and PFS rates were not affected by CXCR4^MUT status on patients treated with proteasome inhibitors. Expert opinion: Our systematic review shows that WM patients with CXCR4^MUT have specific clinical features and have lower response and PFS rates to BTK inhibitors. Our findings support standardization of CXCR4 testing and development of CXCR4-directed therapy.

Targeting the Post-Irradiation Tumor Microenvironment in Glioblastoma via Inhibition of CXCL12

Radiotherapy is a mainstay in glioblastoma therapy as it not only directly targets tumor cells but also depletes the tumor microvasculature. The resulting intra-tumoral hypoxia initiates a chain of events that ultimately leads to re-vascularization, immunosuppression and, ultimately, tumor-regrowth. The key component of this cascade is overexpression of the CXC-motive chemokine ligand 12 (CXCL12), formerly known as stromal-cell derived factor 1 (SDF-1). We here review the role of CXCL12 in recruitment of pro-vasculogenic and immunosuppressive cells and give an overview on future and current drugs that target this axis.

IGFBP7 Drives Resistance to Epidermal Growth Factor Receptor Tyrosine Kinase Inhibition in Lung Cancer

Patients with epidermal growth factor receptor (EGFR) mutation-positive lung cancer show a dramatic response to EGFR-tyrosine kinase inhibitors (TKIs). However, acquired drug resistance eventually develops. This study explored the novel mechanisms related to TKI resistance. To identify the genes associated with TKI resistance, an integrative approach was used to analyze public datasets. Molecular manipulations were performed to investigate the roles of insulin-like growth factor binding protein 7 (IGFBP7) in lung adenocarcinoma. Clinical specimens were collected to validate the impact of IGFBP7 on the efficacy of EGFR TKI treatment. IGFBP7 mRNA expression in cancer cells isolated from malignant pleural effusions after acquired resistance to EGFR-TKI was significantly higher than in cancer cells from treatment-naïve effusions. IGFBP7 expression was markedly increased in cells with long-term TKI-induced resistance compared to in TKI-sensitive parental cells. Reduced IGFBP7 in TKI-resistant cells reversed the resistance to EGFR-TKIs and increased EGFR-TKI-induced apoptosis by up-regulating B-cell lymphoma 2 interacting mediator of cell death (BIM) and activating caspases. Suppression of IGFBP7 attenuated the phosphorylation of insulin-like growth factor 1 receptor (IGF-IR) and downstream protein kinase B (AKT) in TKI-resistant cells. Clinically, higher serum IGFBP7 levels and tumors with positive IGFBP7-immunohistochemical staining were associated with poor TKI-treatment outcomes. IGFBP7 confers resistance to EGFR-TKIs and is a potential therapeutic target for treating EGFR-TKI-resistant cancers.

Targeted Therapy-Resistant Melanoma Cells Acquire Transcriptomic Similarities with Human Melanoblasts

The mechanisms of adaptive and acquired drug resistance in tumors are not completely understood. So far, gene amplifications or mutations, leading to the reactivation of the MAPK or PI3K pathways have been described. In this study, we used two different methods to generate human melanoblasts: (1) via differentiation from induced pluripotent stem cells (iPSCs) and (2) via dedifferentiation from melanocytes. The melanoblast transcriptomes were then compared to the transcriptome of MAPK inhibitor-resistant melanoma cells. We observed that the expression of genes associated with cell cycle control, DNA damage control, metabolism, and cancer was altered in both melanoblast populations and in both adaptive and acquired resistant melanoma samples, compared to drug-sensitive samples. However, genes involved in antigen presentation and cellular movement were only regulated in the melanoblast populations and in the acquired resistant melanoma samples, compared to the drug-sensitive samples. Moreover, melanocyte-derived melanoblasts and adaptive resistant melanoma samples were characterized by different expression levels of certain transcription factors or genes involved in the CDK5 pathway. In conclusion, we show here that in vitro models of human melanoblasts are very important tools to comprehend the expression profiles of drug-resistant melanoma.

CXC family of chemokines as prognostic or predictive biomarkers and possible drug targets in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer in men and the second most common cancer in women, worldwide. In the early stages of the disease, biomarkers predicting early relapse would improve survival rates. In metastatic patients, the use of predictive biomarkers could potentially result in more personalized treatments and better outcomes. The CXC family of chemokines (CXCL1 to 17) are small (8 to 10 kDa) secreted proteins that attract neutrophils and lymphocytes. These chemokines signal through chemokine receptors (CXCR) 1 to 8. Several studies have reported that these chemokines and receptors have a role in either the promotion or inhibition of cancer, depending on their capacity to suppress or stimulate the action of the immune system, respectively. In general terms, activation of the CXCR1/CXCR2 pathway or the CXCR4/CXCR7 pathway is associated with tumor aggressiveness and poor prognosis; therefore, the specific inhibition of these receptors is a possible therapeutic strategy. On the other hand, the lesser known CXCR3 and CXCR5 axes are generally considered to be tumor suppressor signaling pathways, and their stimulation has been suggested as a way to fight cancer. These pathways have been studied in tumor tissues (using immunohistochemistry or measuring mRNA levels) or serum [using enzyme-linked immuno sorbent assay (ELISA) or multiplexing techniques], among other sample types. Common variants in genes encoding for the CXC chemokines have also been investigated as possible biomarkers of the disease. This review summarizes the most recent findings on the role of CXC chemokines and their receptors in CRC and discusses their possible value as prognostic or predictive biomarkers as well as the possibility of targeting them as a therapeutic strategy.

Regulation of Colonic Mucosal MicroRNA Expression via Multiple Targets in Visceral Hypersensitivity Rats by Tongxieyaofang

PURPOSE

This study aimed to screen for differentially expressed microRNAs (miRNAs) in the colons of rats with visceral hypersensitivity to build the expression profiles of miRNAs therein and to determine the mechanism of Tongxieyaofang use in the treatment of irritable bowel syndrome (IBS).

MATERIALS AND METHODS

Forty Sprague-Dawley rats were divided randomly into four groups: control group, model control group (induced by rectum stimulus and evaluated by abdominal withdraw reaction), treatment control group (normal saline), and Tongxieyaofang group (treated with Tongxieyaofang). We screened for differential expression of colonic mucosal miRNAs using liquid chip technology and verified the expression thereof using reverse transcription-PCR.

RESULTS

The visceral hypersensitivity rat model was successfully established. We found the expression of let-7f, let-7i, miR-130b, miR-29a, miR-132, miR-21, and miR-375 to be up-regulated (p<0.05), while the expression of miR-24, miR-31a, miR-192, miR-221, and miR-223 was down-regulated (p<0.05) in the visceral hypersensitivity rats. After treatment with Tongxieyaofang, the expression of let-7f, let-7i, miR-130b, miR-29a, miR-132, miR-21, and miR-375 was reduced (p<0.05), whereas the expression of miR-24, miR-31a, miR-192, miR-221, miR-223 was increased, compared to the treatment control group (p<0.05).

CONCLUSION

MiRNAs play a pivotal role in visceral hypersensitivity and might be targets in the treatment of IBS by Tongxieyaofang.

Functions of the CXC ligand family in the pancreatic tumor microenvironment

Therapeutic resistance is the major contributor to the poor prognosis of and low survival from pancreatic cancer (PC). Cancer progression is a complex process reliant on interactions between the tumor and the tumor microenvironment (TME). Members of the CXCL family of chemokines are present in the pancreatic TME and seem to play a vital role in regulating PC progression. As pancreatic tumors interact with the TME and with PC stem cells (CSCs), determining the roles of specific members of the CXCL family is vital to the development of improved therapies. This review highlights the roles of selected CXCLs in the interactions between pancreatic tumor and its stroma, and in CSC phenotypes, which can be used to identify potential treatment targets.

Feedback control of the CXCR7/CXCL11 chemokine axis by estrogen receptor α in ovarian cancer

Ovarian cancer (OC) is one of the most intractable diseases, exhibiting tremendous molecular heterogeneity and lacking reliable methods for screening, resulting in late diagnosis and widespread peritoneal dissemination. Menopausal estrogen replacement therapy is a well‐recognized risk factor for OC, but little is known about how estrogen might contribute to this disease at the cellular level. This study identifies chemokine receptor CXCR7/ACKR3 as an estrogen‐responsive gene, whose expression is markedly enhanced by estrogen through direct recruitment of ERα and transcriptional active histone modifications in OC cells. The gene encoding CXCR7 chemokine ligand I‐TAC/CXCL11 was also upregulated by estrogen, resulting in Ser‐118 phosphorylation, activation, and recruitment of estrogen receptor ERα at the CXCR7 promoter locus for positive feedback regulation. Both CXCR7 and CXCL11, but not CXCR3 (also recognized to interact with CXCL11), were found to be significantly increased in stromal sections of microdissected tumors and positively correlated in mesenchymal subtype of OC. Estrogenic induction of mesenchymal markers SNAI1, SNAI2, and CDH2 expression, with a consequent increase in cancer cell migration, was shown to depend on CXCR7, indicating a key role for CXCR7 in mediating estrogen upregulation of mesenchymal markers to induce invasion of OC cells. These findings identify a feed‐forward mechanism that sustains activation of the CXCR7/CXCL11 axis under ERα control to induce the epithelial–mesenchymal transition pathway and metastatic behavior of OC cells. Such interplay underlies the complex gene profile heterogeneity of OC that promotes changes in tumor microenvironment and metastatic acquisition.

The CXL12/CXCR4/CXCR7 axis in female reproductive tract disease: Review

Initial studies on the chemokine stromal derived factor 1 (now referred to as CXCL12) were proposed to be enhanced in several diseases including those which affect the female reproductive tract. These include endometriosis, Asherman's syndrome, endometrial cancers, and ovarian cancers. Additionally, recent studies from our laboratory suggest that CXCL12 signaling is involved in leiomyomas (fibroids). These diseases present an inflammatory/hypoxic environment which further promotes pathology. At first, studies focused on signaling by CXCL12 via its well-known receptor, CXCR4. However, the discovery of CXCR7 as another receptor for CXCL12 with rather high binding affinity and recent reports about its involvement in endometrial disease and cancer progression has questioned the potential of "selective blockade"' of CXCR4 to treat these ailments. This review will focus on the signaling and effects of the potent chemokine CXCL12, and its long-known G protein-coupled receptor CXCR4, as well as the alternate receptor CXCR7 on the female reproductive tract and related diseases such as endometriosis, Asherman's syndrome, leiomyomas, endometrial cancer, and ovarian cancer. Although several other mechanisms are inherent to these diseases such as gene mutations, differential expression of miRNAs and epigenetics, for this review, we will focus on the CXCL12/CXCR4/CXCR7 axis as a novel target.

Tunicamycin inhibits colon carcinoma growth and aggressiveness via modulation of the ERK-JNK-mediated AKT/mTOR signaling pathway

Epidemiology and evidence have demonstrated that colon carcinoma is one of the most common gastrointestinal tumors in the clinic. Reports have suggested that Tunicamycin significantly inhibits aggressiveness of colon carcinoma cells by promotion of apoptosis. In the present study, the inhibitory effect of tunicamycin on colon cancer cells and the potential underlying molecular mechanism was investigated. Western blotting, immunohistochemistry, apoptotic assays and immunofluorescence were used to analyze the therapeutic effects of tunicamycin on apoptosis, growth, aggressiveness and cell cycle of colon tumor cells, by downregulation of fibronectin, vimentin and E‑cadherin expression levels. In vitro experiments demonstrated that tunicamycin significantly inhibited growth, migration and invasion of colon carcinoma cells. In addition, tunicamycin administration promoted apoptosis of colon carcinoma cells via upregulation of apoptotic protease activating factor 1 and cytochrome c expression levels, which are proteins that have a role in mitochondrial apoptosis signaling. Cell cycle assays revealed that tunicamycin suppressed proliferation and arrested S phase entry of colon carcinoma cells. Mechanistic analysis demonstrated that tunicamycin reduced expression and phosphorylation levels of extracellular signal‑regulated kinase (ERK), c‑JUN N‑terminal kinase (JNK) and protein kinase B (AKT), and inhibited mammalian target of rapamycin (mTOR) expression levels in colon carcinoma cells. Endogenous overexpression of ERK inhibited tunicamycin‑mediated downregulation of JNK, AKT and mTOR expression, which further blocked tunicamycin‑mediated inhibition of growth and aggressiveness of colon carcinoma. In vivo assays revealed that tunicamycin treatment significantly inhibited tumor growth and promoted apoptosis, which led to long‑term survival of tumor‑bearing mice compared with the control group. In conclusion, these results suggested that tunicamycin may inhibit growth and aggressiveness of colon cancer via the ERK‑JNK‑mediated AKT/mTOR signaling pathway, and suggested that tunicamycin may be a potential anti‑cancer agent for colon carcinoma therapy.

Evolving notions on immune response in colorectal cancer and their implications for biomarker development

INTRODUCTION

Colorectal cancer (CRC) still represents the third most commonly diagnosed type of cancer in men and women worldwide. CRC is acknowledged as a heterogeneous disease that develops through a multi-step sequence of events driven by clonal selections; this observation is sustained by the fact that histologically similar tumors may have completely different outcomes, including a varied response to therapy.

METHODS

In "early" and "intermediate" stage of CRC (stages II and III, respectively) there is a compelling need for new biomarkers fit to assess the metastatic potential of their disease, selecting patients with aggressive disease that might benefit from adjuvant and targeted therapies. Therefore, we review the actual notions on immune response in colorectal cancer and their implications for biomarker development.

RESULTS

The recognition of the key role of immune cells in human cancer progression has recently drawn attention on the tumor immune microenvironment, as a source of new indicators of tumor outcome and response to therapy. Thus, beside consolidated histopathological biomarkers, immune endpoints are now emerging as potential biomarkers.

CONCLUSIONS

The introduction of immune signatures and cellular and molecular components of the immune system as biomarkers is particularly important considering the increasing use of immune-based cancer therapies as therapeutic strategies for cancer patients.

ALDH1A3 affects colon cancer in vitro proliferation and invasion depending on CXCR4 status

Background:

Aldehyde dehydrogenase (ALDH) has been widely used as a marker of cancer stem cells (CSCs). However, the ALDH family includes 19 members, and the most relevant isoforms and their biological functions in cancer biology are still controversial.

Methods:

We examined ALDH enzyme activity and the mRNA expression of 19 ALDH members in 58 human cell lines. The biological effect and mechanism of knocking down ALDH1A3 with siRNA and shRNA in cell lines were explored. Finally, the relationship between ALDH1A3 and CXCR4 was analysed in a large panel of cell lines.

Results:

ALDH1A3 is the key isoform that contributed to Aldefluor positivity in cell lines. Knocking down ALDH1A3 in different cancer cells conferred opposite phenotypes due to differential effects on CXCR4 expression. There was a significant negative correlation between ALDH1A3 and CXCR4 in 58 human cell lines.

Conclusions:

ALDH1A3 was the main contributor to Aldefluor positivity in human cell lines, and its contrasting effects might arise from differences in CXCR4 expression.

Troponin through the looking-glass: emerging roles beyond regulation of striated muscle contraction

Troponin is a heterotrimeric Ca²⁺-binding protein that has a well-established role in regulating striated muscle contraction. However, mounting evidence points to novel cellular functions of troponin, with profound implications in cancer, cardiomyopathy pathogenesis and skeletal muscle aging. Here, we highlight the non-canonical roles and aberrant expression patterns of troponin beyond the sarcomeric milieu. Utilizing bioinformatics tools and online databases, we also provide pathway, subcellular localization, and protein-protein/DNA interaction analyses that support a role for troponin in multiple subcellular compartments. This emerging knowledge challenges the conventional view of troponin as a sarcomere-specific protein exclusively involved in muscle contraction and may transform the way we think about sarcomeric proteins, particularly in the context of human disease and aging.

ACKR3 expression on diffuse large B cell lymphoma is required for tumor spreading and tissue infiltration

Diffuse large B cell lymphoma (DLBCL) is the most frequent lymphoma accounting for more than the 30% of the cases. Involvement of extranodal sites, such as bone marrow and central nervous system, is associated with poor prognosis. A contribution of the chemokine system in these processes is assumed as it is known as a critical regulator of the metastatic process in cancer. The atypical chemokine receptor 3 (ACKR3), which does not couple to G-proteins and does not mediate cell migration, acts as a scavenger for CXCL11 and CXCL12, interfering with the tumor homing CXCL12/CXCR4 axis. Here, functional expression of ACKR3 in DLBCL cells was necessary for colonization of the draining lymph node in an in vivo subcutaneous lymphoma model. Moreover, in a disseminated in vivo lymphoma model, ACKR3 expression was required for bone marrow and brain invasion and local tumor growth. The present data unveil ACKR3 as potential therapeutic target for the control of tumor dissemination in DLBCL.

Galectin-1-driven upregulation of SDF-1 in pancreatic stellate cells promotes pancreatic cancer metastasis

Galectin-1, mainly expressed in activated pancreatic stellate cells (PSCs), is involved in many important cancer-related processes. However, very little is known how Galectin-1 modulates PSCs and subsequently impacts pancreatic cancer cells (PCCs). Our chemokine antibody array and in vitro studies demonstrates that Galectin-1 induces secretion of stromal cell-derived factor-1(SDF-1) in PSCs by activating NF-κB signaling. The secreted SDF-1 increases migration and invasion of PCCs. Knockdown of Galectin-1 and inhibitor-mediated blockade of SDF-1 as well as its ligand CXCR4 and NF-κB verifies the findings. In vivo experiment by knockdown of Galectin-1 in PSCs further demonstrates the conclusion. Collectively, the present studies demonstrate that Galectin-1-driven production of SDF-1 in PSCs through activation of NF-κB promotes metastasis in PDAC, offering a potential target in the treatment of pancreatic cancer.

Giving AXL the axe: targeting AXL in human malignancy

The receptor tyrosine kinase AXL, activated by a complex interaction between its ligand growth arrest-specific protein 6 and phosphatidylserine, regulates various vital cellular processes, including proliferation, survival, motility, and immunologic response. Although not implicated as an oncogenic driver itself, AXL, a member of the TYRO3, AXL, and MERTK family of receptor tyrosine kinases, is overexpressed in several haematologic and solid malignancies, including acute myeloid leukaemia, non-small cell lung cancer, gastric and colorectal adenocarcinomas, and breast and prostate cancers. In the context of malignancy, evidence suggests that AXL overexpression drives wide-ranging processes, including epithelial to mesenchymal transition, tumour angiogenesis, resistance to chemotherapeutic and targeted agents, and decreased antitumor immune response. As a result, AXL is an attractive candidate not only as a prognostic biomarker in malignancy but also as a target for anticancer therapies. Several AXL inhibitors are currently in preclinical and clinical development. This article reviews the structure, regulation, and function of AXL; the role of AXL in the tumour microenvironment; the development of AXL as a therapeutic target; and areas of ongoing and future investigation.

Downregulation of CXCR7 inhibits proliferative capacity and stem cell-like properties in breast cancer stem cells

Breast cancer stem cells (bCSCs) are considered an obstacle in breast cancer therapy because they exhibit long-term proliferative potential, phenotypic plasticity and high resistance to the current therapeutics. CXC chemokine receptor type 7 (CXCR7), which provides a growth advantage to breast cancer cells, has recently been demonstrated to play an important role in the maintenance of stem cell-like properties in the CSCs of glioblastoma and lung cancer, yet its role in bCSCs remains elusive. In this study, CD44⁺/CD24^low bCSC-enriched cells (bCSCs for short) were isolated from MCF-7 cells, and CXCR7 was stably knocked down in bCSCs via lentivirus-mediated transduction with CXCR7 short hairpin RNA (shRNA). Knockdown of CXCR7 in bCSCs decreased the proportion of CD44⁺/CD24^low cells, and markedly reduced the clonogenicity of the cells. Moreover, silencing of CXCR7 downregulated the expression of stem cell markers, such as aldehyde dehydrogenase 1 (ALDH1), Oct4, and Nanog. In addition, CXCR7 silencing in bCSCs suppressed cell proliferation and G1/S transition in vitro, and delayed tumor growth in vivo in a xenograft mouse model. In situ immunohistochemical analysis revealed a reduction in Ki-67 expression and enhanced apoptosis in the xenograft tumors as a result of CXCR7 silencing. Furthermore, combined treatment with CXCR7 silencing and epirubicin displayed an outstanding anti-tumor effect compared with either single treatment. Our study demonstrates that CXCR7 plays a critical role in the maintenance of stem cell-like properties and promotion of growth in bCSCs, and suggests that CXCR7 may be a candidate target for bCSCs in breast cancer therapy.

Paracrine SDF-1α signaling mediates the effects of PSCs on GEM chemoresistance through an IL-6 autocrine loop in pancreatic cancer cells

Pancreatic cancer exhibits the poorest prognosis among all tumors and is characterized by high resistance to the currently available chemotherapeutic agents. Our previous studies have suggested that stromal components could promote the chemoresistance of pancreatic cancer cells (PCCs). Here, we explored the roles of pancreatic stellate cells (PSCs) and the SDF-1α/CXCR4 axis in pancreatic cancer chemoresitance. Our results showed that primary PSCs typically expressed SDF-1α, whereas its receptor CXCR4 was highly expressed in PCCs. PSC-conditioned medium (PSC-CM) inhibited Gemcitabine (GEM)-induced cytotoxicity and apoptosis in the human PCC line Panc-1, which was antagonized by an SDF-1α neutralizing Ab. Recombinant human SDF-1α (rhSDF-1α) increased IL-6 expression and secretion in Panc-1 cells in a time and dose-dependent manner, and this effect was suppressed by the CXCR4 antagonist AMD3100. rhSDF-1α protected Panc-1 cells from GEM-induced apoptosis, and the protective effect was significantly reduced by blocking IL-6 using a neutralizing antibody. Moreover, rhSDF-1α increased FAK, ERK1/2, AKT and P38 phosphorylation in Panc-1 cells, and either FAK or ERK1/2 inhibition suppressed SDF-1α-upregulated IL-6 expression. SDF-1α-induced AKT activation was almost completely blocked by FAK inhibition. In conclusion, we demonstrate for the first time that PSCs promote the chemoresistance of PCCs to GEM, and this effect is mediated by paracrine SDF-1α/CXCR4 signaling-induced activation of the intracellular FAK-AKT and ERK1/2 signaling pathways and a subsequent IL-6 autocrine loop in PCCs. Our findings indicate that blocking the PSC-PCC interaction by inhibiting SDF-1α/CXCR4 signaling may be a promising therapeutic strategy for overcoming chemoresistance in pancreatic cancer.

miR-100 suppresses the proliferation and tumor growth of esophageal squamous cancer cells via targeting CXCR7

MicroRNAs are highly conserved non-coding RNAs that regulate gene expression at the post-transcriptional level, and play pivotal roles in cancer development and progression. miR-100 has been reported to be significantly downregulated in a variety of cancers, including esophageal cancer. However, the role of miR-100 in human esophageal cancer has not been fully elucidated. We demonstrated that overexpression of miR-100 in esophageal cancer cells markedly inhibited cell proliferation, migration and invasion as well as tumor growth. We subsequently showed that CXCR7 is a direct target gene of miR-100. Our results indicated that miR-100 plays a tumor-suppressor role in esophageal cancer and suggest its potential application for esophageal cancer treatment.

The relationship between prenatal exposure to BP-3 and Hirschsprung's disease

Hirschsprung's disease (HSCR) is neonatal intestinal abnormality which derived from the faliure of enteric neural crest cells migration to hindgut during embryogenesis from 5 to 12 weeks. Currenly, the knowledge of environmental factors contributing to HSCR is still scarce. Benzophenone-3 (BP-3) is one of the most widely used UV filters, and has weak estrogen and strong anti-androgenic effects. In order to examine the effect of maternal BP-3 exposure on development of offspring and explore the potential mechanism, we conducted case and control study and in vitro study. In this work, BP-3 concertrations in maternal urine was detected by ultra-high performance liquid chromatography. Besides, we investigated the cytotoxicity and receptor tyrosine kinase (RET) expression in cells exposed to BP-3. The results showed that maternal BP-3 exposure was associated with offspring's HSCR in the population as well as inhibited migration of 293T and SH-SY5Y cells. What's more, we discovered dose-response relationship between RET expression and BP-3 exposure dose, and miR-218 and some other genes involved in SLIT2/ROBO1-miR-218-RET/PLAG1 pathway were also related to BP-3 exposure. Therefore, we deduced that BP-3 influenced cell migration via SLIT2/ROBO1-miR-218-RET/PLAG1 pathway. Our study firstly revealed the relationship between maternal BP-3 exposure and HSCR as well as its potential mechanism.

C-X-C motif receptor 7 in gastrointestinal cancer

Chemokine receptors are key mediators of normal physiology and numerous pathological conditions, including inflammation and cancer. This receptor family is an emerging target for anticancer drug development. C-X-C motif receptor 7 (CXCR7) is an atypical chemokine receptor that was first cloned from a canine cDNA library as an orphan receptor and was initially named receptor dog cDNA 1 (RDC1). Shortly after demonstrating that RDC1 binds with its ligand, stromal cell-derived factor-1α and interferon-inducible T-cell α chemoattractant, RDC1 was officially deorphanized and renamed CXCR7, as the seventh receptor in the CXC class of the chemokine receptor family. Recent accumulating evidence has demonstrated that CXCR7 expression is augmented in the majority of tumor cells compared with their normal counterparts and is involved in cell proliferation, survival, migration, invasion and angiogenesis during the initiation and progression of breast, lung and prostate cancer. In the present review, the expression and role of CXCR7, as well as its clinical relevance in cancer of the gastrointestinal system, were investigated. In addition, the potential of this chemokine receptor as a therapeutic target in the treatment of gastrointestinal cancer was discussed.

Mismatch repair status and synchronous metastases in colorectal cancer: A nationwide cohort study

The causality between the metastatic potential, mismatch repair status (MMR) and survival in colorectal cancer (CRC) is complex. This study aimed to investigate the impact of MMR in CRC on the occurrence of synchronous metastases (SCCM) and survival in patients with SCCM on a national basis. A nationwide cohort study of 6,692 patients diagnosed with CRC between 2010 and 2012 was conducted. Data were prospectively entered into the Danish Colorectal Cancer Group's database and merged with data from the Danish Pathology Registry and the National Patient Registry. Multivariable and multinomial logistic- and Cox-regression and proportional excess hazards analyses were used for confounder adjustment and to adjust for the general population mortality. In total, 983 of 6,692 patients (14.7%) had dMMR and 935 (14.0%) had SCCM. dMMR was associated with a decreased risk of SCCM, adjusted Odds Ratio (aOR) = 0.54 (95% confidence interval (CI):0.40-0.70, p < 0.001). The association only applied to confined hepatic metastases (aOR = 0.30, 95%CI: 0.18-0.49, p < 0.001), whereas the presence of confined pulmonary metastases (aOR = 0.71, 95% CI: 0.39-1.29, p = 0.258) or synchronous hepatic and pulmonary metastases (aOR = 0.69, 95% CI:0.26-1.29, p = 0.436) were unaffected by MMR. MMR in patients with SCCM had no impact on survival (Cox: adjusted Hazard Ratio (aHR) = 0.76, 95% CI: 0.54-1.06, p = 0.101; Proportional excess hazards: aHR = 0.73, 95% CI: 0.50-1.07, p = 0.111) when adjusting for other prognostic factors. The metastatic pattern varied according to MMR status. MMR had no impact on survival in patients with UICC Stage IV CRC. These findings may be important for the understanding of the metastatic processes and thus for optimizing staging and treatment in CRC patients.

The critical roles of tumor-initiating cells and the lymph node stromal microenvironment in human colorectal cancer extranodal metastasis using a unique humanized orthotopic mouse model

Colorectal cancer (CRC) is the second-most common cause of cancer-related mortality. The most important prognostic factors are lymph node (LN) involvement and extranodal metastasis. Our objective is to investigate the interactions between CD133(+)CXCR4(+) (CXC receptor 4) colorectal cancer tumor-initiating cells (Co-TICs) and the LN stromal microenvironment in human CRC extranodal metastasis. We established a unique humanized orthotopic xenograft model. Luciferase-tagged CRC cell lines and human cancer cells were injected intrarectally into nonobese diabetic/SCID mice. Mesenteric LN stromal cells, stromal cell line HK, or CXCL12 knockdown HK (HK-KD-A3) cells were coinoculated with CRC cells. Tumor growth and metastasis were monitored by bioluminescent imaging and immunohistochemistry. We found that this model mimics the human CRC metastatic pattern with CRC cell lines or patient specimens. Adding LN stromal cells promotes CRC tumor growth and extranodal metastasis (P < 0.001). Knocking down CXCL12 impaired HK cell support of CRC tumor formation and extranodal metastasis. When HK cells were added, sorted CD133(+)CXCR4(+) Co-TICs showed increased tumor formation and extranodal metastasis capacities compared to unseparated and non-Co-TIC populations. In conclusion, both Co-TIC and LN stromal factors play crucial roles in CRC metastasis through the CXCL12/CXCR4 axis. Blocking Co-TIC/LN-stromal interactions may lead to effective therapy to prevent extranodal metastasis.

miR-218 inhibits the invasion and migration of colon cancer cells by targeting the PI3K/Akt/mTOR signaling pathway

Colon cancer is one of the most common and lethal malignancies worldwide. Despite major advances in the treatment of colon cancer, the prognosis remains very poor. Thus, novel and effective therapies for colon cancer are urgently needed. In the present study, the expression status of miR-218 and the role of the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway were investigated in colon cancer samples. Firstly, we observed that miR-218 expression was significantly reduced, while PI3K/Akt/mTOR pathway activity was enhanced. The overexpression of miR-218 suppressed the proliferation, migration and invasion of LoVo colon cancer cells, whereas the inhibition of miR-218 promoted these processes. Furthermore, the PI3K/Akt/mTOR signaling pathway was identified as a direct target of miR-218. The upregulation of miR-218 inhibited the activation of the PI3K/Akt/mTOR signaling pathway, as well as the expression of matrix metalloproteinase (MMP)9. The downregulation of miR-218 activated the PI3K/Akt/mTOR signaling pathway and promoted MMP9 expression. Taken together, our results demonstrate that miR-218 suppresses the proliferation, migration and invasion of LoVo colon cancer cells by targeting the PI3K/Akt/mTOR signaling pathway and MMP9. Our data indicate that miR-218 is a potential target in the treatment of colon cancer.

Axl as a mediator of cellular growth and survival

The control of cellular growth and proliferation is key to the maintenance of homeostasis. Survival, proliferation, and arrest are regulated, in part, by Growth Arrest Specific 6 (Gas6) through binding to members of the TAM receptor tyrosine kinase family. Activation of the TAM receptors leads to downstream signaling through common kinases, but the exact mechanism within each cellular context varies and remains to be completely elucidated. Deregulation of the TAM family, due to its central role in mediating cellular proliferation, has been implicated in multiple diseases. Axl was cloned as the first TAM receptor in a search for genes involved in the progression of chronic to acute-phase leukemia, and has since been established as playing a critical role in the progression of cancer. The oncogenic nature of Axl is demonstrated through its activation of signaling pathways involved in proliferation, migration, inhibition of apoptosis, and therapeutic resistance. Despite its recent discovery, significant progress has been made in the development of effective clinical therapeutics targeting Axl. In order to accurately define the role of Axl in normal and diseased processes, it must be analyzed in a cell type-specific context.

Mutational analysis of genes coding for cell surface proteins in colorectal cancer cell lines reveal novel altered pathways, druggable mutations and mutated epitopes for targeted therapy

We carried out a mutational analysis of 3,594 genes coding for cell surface proteins (Surfaceome) in 23 colorectal cancer cell lines, searching for new altered pathways, druggable mutations and mutated epitopes for targeted therapy in colorectal cancer. A total of 3,944 somatic non-synonymous substitutions and 595 InDels, occurring in 2,061 (57%) Surfaceome genes were catalogued. We identified 48 genes not previously described as mutated in colorectal tumors in the TCGA database, including genes that are mutated and expressed in >10% of the cell lines (SEMA4C, FGFRL1, PKD1, FAM38A, WDR81, TMEM136, SLC36A1, SLC26A6, IGFLR1). Analysis of these genes uncovered important roles for FGF and SEMA4 signaling in colorectal cancer with possible therapeutic implications. We also found that cell lines express on average 11 druggable mutations, including frequent mutations (>20%) in the receptor tyrosine kinases AXL and EPHA2, which have not been previously considered as potential targets for colorectal cancer. Finally, we identified 82 cell surface mutated epitopes, however expression of only 30% of these epitopes was detected in our cell lines. Notwithstanding, 92% of these epitopes were expressed in cell lines with the mutator phenotype, opening new venues for the use of "general" immune checkpoint drugs in this subset of patients.

Low expression levels of microRNA-124-5p correlated with poor prognosis in colorectal cancer via targeting of SMC4

A component of polycomb repressor complex 2, enhancer of zeste homolog 2 (EZH2), plays an important role in tumor malignancy and metastasis, while milk fat globule-epidermal growth factor-factor 8 (MFGE8) plays a key role in tumor progression and prognosis. MicroRNAs (miRs) are also critically involved in various physiological and pathological processes. We here evaluated the relationship between overall survival (OS) in colorectal cancer patients and the expression of onco-miRs and miRs, which may target EZH2 and MFGE8. Plasma and formalin-fixed paraffin-embedded (FFPE) samples were obtained from 71 colorectal cancer patients. The expression levels of miRs complementary to EZH2 and MFGE8 mRNA and cancer malignancies were evaluated. The miRs analyzed were as follows: miR-16, miR-21, miR-26a, miR-34a, miR-98, miR-101-3p, miR-101-5p, miR-124-5p (also known as miR-124*), miR-126-3p, miR-126-5p, miR-210, miR-217, and miR-630. The plasma expression levels of MFGE8 in completely resected patients were significantly lower than those in unresectable patients. Lower miR-26a expression levels were correlated with a higher probability of OS. Higher miR-124-5p expression levels in plasma and FFPE samples were correlated with a higher probability of OS. The transfection of mimic miR-124-5p into WiDr and COLO201 cells inhibited the expression of structural maintenance of chromosomes 4 (SMC4) mRNA. Our results indicate that miR-124-5p may target the tumorigenesis gene, SMC4, which suggests that expression levels of miR-124-5p in plasma and FFPE samples; therefore, the expression of MFGE8, miR-26a, and miR-124-5p in plasma may be used as biomarkers to determine the prognosis of colorectal cancer patients.