The PDGF-D/miR-106a/Twist1 pathway orchestrates epithelial-mesenchymal transition in gemcitabine resistance hepatoma cells. Oncotarget. 2015;6:7000-7010. [PMID: 25760076 DOI: 10.18632/oncotarget.3193]

Understanding the Role of Connexins in Hepatocellular Carcinoma: Molecular and Prognostic Implications

Connexins, a family of tetraspan membrane proteins forming intercellular channels localized in gap junctions, play a pivotal role at the different stages of tumor progression presenting both pro- and anti-tumorigenic effects. Considering the potential role of connexins as tumor suppressors through multiple channel-independent mechanisms, their loss of expression may be associated with tumorigenic activity, while it is hypothesized that connexins favor the clonal expansion of tumor cells and promote cell migration, invasion, and proliferation, affecting metastasis and chemoresistance in some cases. Hepatocellular carcinoma (HCC), characterized by unfavorable prognosis and limited responsiveness to current therapeutic strategies, has been linked to gap junction proteins as tumorigenic factors with prognostic value. Notably, several members of connexins have emerged as promising markers for assessing the progression and aggressiveness of HCC, as well as the chemosensitivity and radiosensitivity of hepatocellular tumor cells. Our review sheds light on the multifaceted role of connexins in HCC pathogenesis, offering valuable insights on recent advances in determining their prognostic and therapeutic potential.

Overview of miR-106a Regulatory Roles: from Cancer to Aging

MicroRNAs (miRNAs) comprise a class of non-coding RNA with extensive regulatory functions within cells. MiR-106a is recognized for its super-regulatory roles in vital processes. Hence, the analysis of its expression in association with diseases has attracted considerable attention for molecular diagnosis and drug development. Numerous studies have investigated miR-106 target genes and shown that this miRNA regulates the expression of some critical cell cycle and apoptosis factors, suggesting miR-106a as an ideal diagnostic and prognostic biomarker with therapeutic potential. Furthermore, the reported correlation between miR-106a expression level and cancer drug resistance has demonstrated the complexity of its functions within different tissues. In this study, we have conducted a comprehensive review on the expression levels of miR-106a in various cancers and other diseases, emphasizing its target genes. The promising findings surrounding miR-106a suggest its potential as a valuable biomolecule. However, further validation assessments and overcoming existing limitations are crucial steps before its clinical implementation can be realized.

Autophagy orchestrates resistance in hepatocellular carcinoma cells

Treatment resistance is one of the major barriers for therapeutic strategies in hepatocellular carcinoma (HCC). Many studies have indicated that chemotherapy and radiotherapy induce autophagy machinery (cell protective autophagy) in HCC cells. In addition, many experiments report a remarkable crosstalk between treatment resistance and autophagy pathways. Thus, autophagy could be one of the key factors enabling tumor cells to hinder induced cell death after medical interventions. Therefore, extensive research on the molecular pathways involved in resistance induction and autophagy have been conducted to achieve the desired therapeutic response. The key molecular pathways related to the therapy resistance are TGF-β, MAPK, NRF2, NF-κB, and non-coding RNAs. In addition, EMT, drug transports, apoptosis evasion, DNA repair, cancer stem cells, and hypoxia could have considerable impact on the hepatoma cell's response to therapies. These mechanisms protect tumor cells against various treatments and many studies have shown that each of them is connected to the molecular pathways of autophagy induction in HCC. Hence, autophagy inhibition may be an effective strategy to improve therapeutic outcome in HCC patients. In this review, we further highlight how autophagy leads to poor response during treatment through a complex molecular network and how it enhances resistance in primary liver cancer. We propose that combinational regimens of approved HCC therapeutic protocols plus autophagy inhibitors may overcome drug resistance in HCC therapy.

TWIST1 is a prognostic factor for neoadjuvant chemotherapy for patients with resectable pancreatic cancer: a preliminary study

Recent advances in the development of chemotherapies have helped improve the prognosis of pancreatic ductal adenocarcinoma (PDAC). However, predicting factors for the outcomes of chemotherapies (either gemcitabine or S-1) have not yet been established. We analyzed the expression of 4 major epithelial-to-mesenchymal transition-inducing transcription factors in 38 PDAC patients who received adjuvant chemotherapy after radical resection to examine the association with patients' prognoses. The TWIST1-positive group showed a significantly poorer prognosis than the TWIST1-negative group for both the relapse-free survival (median survival time [MST] of 8.9 vs. 18.5 months, P = 0.016) and the overall survival (MST of 15.2 vs. 33.4 months, P = 0.023). A multivariate analysis revealed that TWIST1 positivity was an independent prognostic factor for a poor response to adjuvant chemotherapies (hazard ratio 2.61; 95% confidence interval 1.10-6.79; P = 0.029). These results suggest that TWIST1 can be utilized as an important poor prognostic factor for radically resected PDAC patients with adjuvant chemotherapy, potentially including neoadjuvant therapy using these agents.

Combination therapy with chitosan/siRNA nanoplexes targeting PDGF-D and PDGFR-β reveals anticancer effect in breast cancer

BACKGROUND

Platelet derived growth factors (PDGF)-D and the expression of its receptor increase in neoplastic progression of cancer. Co-silencing of growth factor and receptor can be suggested as an important strategy for effective cancer therapy. In the present study, we hypothesized that suppression of PDGF-D signaling pathway with small interfering RNAs (siRNAs) targeting both PDGF-D and PDGF receptor (PDGFR)-β is a promising strategy for anticancer therapy.

METHODS

Chitosan nanoplexes containing dual and single siRNA were prepared at different weight ratios and controlled by gel retardation assay. Characterization, cellular uptake, gene silencing and invasion studies were performed. The effect of nanoplexes on breast tumor growth, PDGF expression and apoptosis was investigated.

RESULTS

We have shown that downregulation of PDGF-D and PDGFR-β with chitosan/siRNA nanoplex formulations reduced proliferation and invasion in breast cancer cells. In the in vivo breast tumor model, it was determined that the intratumoral administration of chitosan/siPDGF-D/siPDGFR-β nanoplexes markedly decreased the tumor volume and PDGF-D and PDGFR-β mRNA and protein expression levels and increased apoptosis.

CONCLUSIONS

According to the results obtained, we evaluated the effect of PDGF-D and PDGFR-β on breast tumor development and showed that RNAi-mediated inhibition of this pathway formulated with chitosan nanoplexes can be considered as a new breast cancer therapy strategy.

Noncoding RNA-mediated molecular bases of chemotherapy resistance in hepatocellular carcinoma

Despite the significant progress in decreasing the occurrence and mortality of hepatocellular carcinoma (HCC), it remains a public health issue worldwide on the basis of its late presentation and tumor recurrence. To date, apart from surgical interventions, such as surgical resection, liver transplantation and locoregional ablation, current standard antitumor protocols include conventional cytotoxic chemotherapy. However, due to the high chemoresistance nature, most current therapeutic agents show dismal outcomes for this refractory malignancy, leading to disease relapse. Nevertheless, the molecular mechanisms involved in chemotherapy resistance remain systematically ambiguous. Herein, HCC is hierarchically characterized by the formation of primitive cancer stem cells (CSCs), progression of epithelial-mesenchymal transition (EMT), unbalanced autophagy, delivery of extracellular vesicles (EVs), escape of immune surveillance, disruption of ferroptosis, alteration of the tumor microenvironment and multidrug resistance-related signaling pathways that mediate the multiplicity and complexity of chemoresistance. Of note, anecdotal evidence has corroborated that noncoding RNAs (ncRNAs) extensively participate in the critical physiological processes mentioned above. Therefore, understanding the detailed regulatory bases that underlie ncRNA-mediated chemoresistance is expected to yield novel insights into HCC treatment. In the present review, a comprehensive summary of the latest progress in the investigation of chemotherapy resistance concerning ncRNAs will be elucidated to promote tailored individual treatment for HCC patients.

Extracellular Vesicles and Resistance to Anticancer Drugs: A Tumor Skeleton Key for Unhinging Chemotherapies

Although surgical procedures and clinical care allow reaching high success in fighting most tumors, cancer is still a formidable foe. Recurrence and metastatization dampen the patients’ overall survival after the first diagnosis; nevertheless, the large knowledge of the molecular bases drives these aspects. Chemoresistance is tightly linked to these features and is mainly responsible for the failure of cancer eradication, leaving patients without a crucial medical strategy. Many pathways have been elucidated to trigger insensitiveness to drugs, generally associated with the promotion of tumor growth, aggressiveness, and metastatisation. The main mechanisms reported are the expression of transporter proteins, the induction or mutations of oncogenes and transcription factors, the alteration in genomic or mitochondrial DNA, the triggering of autophagy or epithelial-to-mesenchymal transition, the acquisition of a stem phenotype, and the activation of tumor microenvironment cells. Extracellular vesicles (EVs) can directly transfer or epigenetically induce to a target cell the molecular machinery responsible for the acquisition of resistance to drugs. In this review, we resume the main body of knowledge supporting the crucial role of EVs in the context of chemoresistance, with a particular emphasis on the mechanisms related to some of the main drugs used to fight cancer.

miRNAs inspirations in hepatocellular carcinoma: Detrimental and favorable aspects of key performers

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related deaths worldwide. HCC initiation, progression, and therapy failure are all influenced by various variables, including microRNAs (miRNAs). miRNAs are short non-coding RNA sequences that modulate target mRNA expression by deteriorating or repressing translation. miRNAs play an imperative role in HCC pathogenesis by triggering the induction of cancer stem cells (CSCs) and their proliferation, while also delaying apoptosis, sustaining the cell cycle, and inspiring angiogenesis, invasion, and metastasis. Additionally, miRNAs modulate crucial HCC-related molecular pathways such as the p53 pathway, the Wnt/β-catenin pathway, VEGFR2, and PTEN/PI3K/AKT pathway. Consequently, the goal of this review was to give an up-to-date overview of oncogenic and tumor suppressor (TS) miRNAs, as well as their potential significance in HCC pathogenesis and treatment responses, highlighting their underpinning molecular pathways in HCC initiation and progression. Similarly, the biological importance and clinical application of miRNAs in HCC are summarized.

Germline Variants and Genetic Interactions of Several EMT Regulatory Genes Increase the Risk of HBV-Related Hepatocellular Carcinoma

Epithelial-mesenchymal transition (EMT) plays an important role in the development of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). We hypothesized that germline variants in the major EMT regulatory genes (SNAIL1, ZEB1, ZEB2, TWIST1) may influence the development of HBV-related HCC. We included 421 cases of HBsAg-positive patients with HCC, 1371 cases of HBsAg-positive subjects without HCC [patients with chronic hepatitis B (CHB) or liver cirrhosis (LC)] and 618 cases of healthy controls in the case-control study. Genotype, allele, and haplotype associations in the major EMT regulatory genes were tested. Environment-gene and gene-gene interactions were analysed using the non-parametric model-free multifactor dimensionality reduction (MDR) method. The SNAIL1rs4647958T>C was associated with a significantly increased risk of both HCC (CT+CC vs. TT: OR=1.559; 95% confidence interval [CI], 1.073-2.264; P=0.020) and CHB+LC (CT+CC vs. TT: OR=1.509; 95% CI, 1.145-1.988; P=0.003). Carriers of the TWIST1rs2285681G>C (genotypes CT+CC) had an increased risk of HCC (CG+CC vs. GG: OR=1.407; 95% CI, 1.065-1.858; P=0.016). The ZEB2rs3806475T>C was associated with significantly increased risk of both HCC (P _recessive =0.001) and CHB+LC (P _recessive<0.001). The CG haplotype of the rs4647958/rs1543442 haplotype block was associated with significant differences between healthy subjects and HCC patients (P=0.0347). Meanwhile, the CT haplotype of the rs2285681/rs2285682 haplotype block was associated with significant differences between CHB+LC and HCC patients (P=0.0123). In MDR analysis, the combination of TWIST1rs2285681, ZEB2rs3806475, SNAIL1rs4647958 exhibited the most significant association with CHB+LC and Health control in the three-locus model. Our results suggest significant single-gene associations and environment-gene/gene-gene interactions of EMT-related genes with HBV-related HCC.

linc‑ROR facilitates hepatocellular carcinoma resistance to doxorubicin by regulating TWIST1‑mediated epithelial‑mesenchymal transition

Long non‑coding RNAs are associated with cancer progression. Long intergenic non‑protein coding RNA (linc)‑regulator of reprogramming (ROR) enhances tumor development in hepatocellular carcinoma (HCC). However, the effect of chemoresistance and its underlying mechanisms in HCC are not completely understood. The present study aimed to identify the effect of ROR on sensitivity to doxorubicin (DOX) in HCC cells. In the present study, Cell Counting Kit‑8 and EdU assays were performed to assess cell viability and proliferation, respectively. In addition, E‑cadherin and vimentin protein expression levels were assessed via western blotting and immunofluorescence.The results of the present study demonstrated that HCC cells with high linc‑ROR expression levels were more resistant to DOX, and linc‑ROR knockdown increased HCC cell DOX sensitivity compared with the control group. The results indicated that compared with the NC siRNA group, linc‑ROR knockdown notably suppressed epithelial‑mesenchymal transition by downregulating twist family bHLH transcription factor 1 (TWIST1) expression. TWIST1 knockdown displayed a similar effect on HCC cell DOX sensitivity to linc‑ROR knockdown. Moreover, linc‑ROR knockdown‑induced HCC cell DOX sensitivity was inhibited by TWIST1 overexpression. The present study provided evidence that linc‑ROR promoted HCC resistance to DOX by inducing EMT via interacting with TWIST1. Therefore, linc‑ROR might serve as a therapeutic target for reducing DOX resistance in HCC.

MicroRNAs Modulate Drug Resistance-Related Mechanisms in Hepatocellular Carcinoma

Primary liver cancer [hepatocellular carcinoma (HCC)] is one of the most common malignant tumors worldwide, causing serious health threats because of its high morbidity and mortality, rapid growth, and strong invasiveness. Patients with HCC frequently develop resistance to the current chemotherapeutic drugs, and this is largely attributed to the high-level heterogeneity of the tumor tissue. MicroRNAs (miRNAs) are a group of master regulators for multiple physiological and pathological processes and play important roles in the tumorigenesis. More recent studies have indicated that miRNAs also play a non-negligible role in the development of drug resistance in liver cancer. In this review, we summarize the data from the latest studies on the mechanisms of drug resistance in liver cancer, including autophagy, membrane transporters, epithelial-mesenchymal transitions (EMTs), tumor microenvironment, and genes and proteins that are associated with apoptosis. The data herein will provide valuable information for the development of novel approaches to tackle drug resistance in the management of liver cancer.

The Underlying Mechanisms of Noncoding RNAs in the Chemoresistance of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most lethal human malignancies. Chemotherapeutic agents, such as sorafenib and lenvatinib, can improve the outcomes of HCC patients. Nevertheless, chemoresistance has become a major hurdle in the effective treatment of HCC. Noncoding RNAs (ncRNAs), including mircoRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs), have been demonstrated to participate in the onset and progression of HCC. Moreover, multiple lines of evidence have indicated that ncRNAs also play a pivotal role in HCC drug resistance. ncRNAs can regulate drug efflux and metabolism, glucose metabolism, cellular death pathways, and malignant characteristics in HCC. A deeper understanding of the molecular mechanisms responsible for ncRNA-mediated drug resistance in HCC will provide new opportunities for improving the treatment of HCC. In this review, we summarize recent findings on the molecular mechanisms by which ncRNAs regulate HCC chemoresistance, as well as their potential clinical implications in overcoming HCC chemoresistance.

PDGFD induces ibrutinib resistance of diffuse large B‑cell lymphoma through activation of EGFR

Ibrutinib, an FDA approved, orally administered BTK inhibitor, has demonstrated high response rates to diffuse large B-cell lymphoma (DLBCL), however, complete responses are infrequent and acquired resistance to BTK inhibition can emerge. The present study investigated the role of the platelet-derived growth factor D (PDGFD) gene and the ibrutinib resistance of DLBCL in relation to epidermal growth factor receptor (EGFR). Bioinformatics was used to screen and analyze differentially expressed genes (DEGs) in complete response (CR), partial response (PR) and stable disease (SD) in DLBCL treatment with ibrutinib, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to analyze enriched the signaling pathways increasing DEGs. The Search Tool for Interactions of Chemicals database was used to analyze the target genes of ibrutinib. An interaction network of DEGs, disease-related genes and ibrutinib was constructed. The expression of PDGFD in tissues that were resistant or susceptible to DLBCL/ibrutinib was detected via immunohistochemistry (IHC), and the expression of PDGFD in DLBCL/ibrutinib-resistant strains and their parental counterparts were examined via reverse transcription-quantitative PCR and western blot analyses. Subsequently, a drug-resistant cell model of DLBCL/ibrutinib in which PDGFD was silenced was constructed. The apoptosis of the DLBCL/ibrutinib-resistant strains was examined using MTT and flow cytometry assays. EGFR gene expression was then assessed. At the same time, a PDGFD-interfering plasmid and an EGFR overexpression plasmid were transfected into the DLBCL drug-resistant cells (TMD8-ibrutinib, HBL1-ibrutinib) separately or together. MTT was used to measure cell proliferation and changes in the IC₅₀ of ibrutinib. A total of 86 DEGs that increased in the CR, PR and SD tissues were screened, and then evaluated with GO and KEGG. The interaction network diagram showed that there was a regulatory relationship between PDGFD and disease-related genes, and that PDGFD could indirectly target the ibrutinib target gene EGFR, indicating that PDGFD could regulate DLBCL via EGFR. IHC results showed high expression of PDGFD in diffuse large B-cell lymphoma tissues with ibrutinib tolerance. PDGFD expression in ibrutinib-resistant DLBCL cells was higher compared with in parental cells. Following interference with PDGFD expression in ibrutinib-resistant DLBCL cells, the IC₅₀ value of ibrutinib decreased, the rate of apoptosis increased and EGFR expression decreased. In brief, EGFR overexpression can reverse the resistance of DLBCL to ibrutinib via PDGFD interference, and PDGFD induces the resistance of DLBCL to ibrutinib via EGFR.

Diabetic nephropathy execrates epithelial-to-mesenchymal transition (EMT) via miR-2467-3p/Twist1 pathway

Although diabetic nephropathy (DN) is induced by a complicate interplay of multiple factors, the underlying mechanisms remain poorly characterized, even the treatment. Herein, we show that both of DN patients and STZ-induced type 1 diabetic rat exhibit the reduction both of urinary and circulating miR-2467-3p. We identify a negative correlation between miR-2467-3p levels and renal dysfunction. Administration of miR-2467-3p prevents diabetes-induced renal dysfunction and represses renal fibrosis in STZ-induced type 1 diabetic rats. Conversely, anti-miR-2467 overexpression exacerbates renal dysfunction and fibrosis in STZ-induced rats. In diabetic condition, the reduction of miR-2467-3p promotes expression of Twist1, inducing epithelial-to-mesenchymal transition (EMT), resulting in renal fibrosis and kidney dysfunction. Together, our study presents miR-2467/Twist1/EMT as a regulatory axis of renal dysfunction in DN.

Crosstalk between miR-215 and epithelial-mesenchymal transition specific markers (E-cadherin and N-cadherin) in different stages of chronic HCV Infection

The main causes of death among patients with hepatocellular carcinoma (HCC) are a recurrence, metastasis, and deterioration of primary tumors by the epithelial-to-mesenchymal transition (EMT) which is controlled by several molecules including E-cadherin and N-cadherin. Microribonucleic acids (miRNAs) have been identified to play a regulatory role in EMT. miR-215 is important in repressing migration/invasion of cancer cells. In this study, we aimed to evaluate the crosstalk between miR-215 and EMT specific markers (E-cadherin and N-cadherin) with a spotlight on its role in the EMT process in hepatitis C virus (HCV)-infected patients. One hundred forty-five patients were studied, 75 had HCV-induced cirrhosis classified into child A, B, and C and 25 had HCC. In parallel, 45 healthy volunteers considered as controls. Serum levels of E- and N-cadherin were measured using enzyme-linked immunosorbent assay and miR-215 expression measured by a quantitative reverse transcription-polymerase chain reaction. Insignificant change in serum levels of E-cadherin and N-cadherin in HCV-infected patients compared with normal controls was observed with a slight increase in E-cadherin and N-cadherin in the child B group. HCC patients had the lowest amount of E-cadherin and N-cadherin compared with cirrhotic and normal subjects. A maximum reduction in miR-215 was observed in HCC patients compared with cirrhotic and control ones. A positive correlation (r = .202; P < .05) was observed between miR-215 and E-cadherin. Our data stressed on the potential role of miR-215 as an important mediator in HCC progression. miRNAs participating in EMT needs further studies to provide insight into the metastasis of HCC.

Platelets and Hepatocellular Cancer: Bridging the Bench to the Clinics

Growing interest is recently being focused on the role played by the platelets in favoring hepatocellular cancer (HCC) growth and dissemination. The present review reports in detail both the experimental and clinical evidence published on this topic. Several growth factors and angiogenic molecules specifically secreted by platelets are directly connected with tumor progression and neo-angiogenesis. Among them, we can list the platelet-derived growth factor, the vascular endothelial growth factor, the endothelial growth factor, and serotonin. Platelets are also involved in tumor spread, favoring endothelium permeabilization and tumor cells’ extravasation and survival in the bloodstream. From the bench to the clinics, all of these aspects were also investigated in clinical series, showing an evident correlation between platelet count and size of HCC, tumor biological behavior, metastatic spread, and overall survival rates. Moreover, a better understanding of the mechanisms involved in the platelet–tumor axis represents a paramount aspect for optimizing both current tumor treatment and development of new therapeutic strategies against HCC.

Inhibitory effects of genistein in combination with gefitinib on the hepatocellular carcinoma Hep3B cell line

Combination therapy is an important method for treating advanced hepatocellular carcinoma (HCC). Gefitinib is an epidermal growth factor receptor (EGFR) inhibitor, which has profound effects on HCC. The purpose of the present study was to investigate the effects of genistein in combination with gefitinib on the proliferation and apoptosis of HCC cells and the associated mechanism. Cell counting kit-8 assay was performed to calculate the IC₅₀ values and cytotoxicity, whilst flow cytometry was used to assess cell apoptosis. Protein expression was detected using western blot analysis. The IC₅₀ of genistein and gefitinib on Hep3B cells were calculated to be 128.078 and 13.657 µM, respectively. Genistein in combination with gefitinib significantly inhibited cell viability, promoted apoptosis and reduced EGFR, vascular endothelial growth factor receptor and platelet-derived growth factor receptor phosphorylation. Genistein in combination with gefitinib promoted the expression of cleaved caspase-3 and cleaved poly ADP-ribose polymerase. In addition, combined treatment of genistein and gefitinib strongly inhibited the activation of the Akt/Erk/mTOR signaling pathway. In conclusion, findings from the present study suggest that genistein in combination with gefitinib inhibit HCC cell proliferation and promote apoptosis by inhibiting the Akt/Erk/mTOR pathway.

Connexin 32 downregulation is critical for chemoresistance in oxaliplatin-resistant HCC cells associated with EMT

Background: Oxaliplatin (OXA)-based chemotherapy is critical in the management of advanced hepatocellular carcinoma (HCC); however, acquired drug resistance has largely restricted its clinical efficacy. This study aims to explore the key mechanisms and regulatory factors determining chemosensitivity in HCC.

Methods: We developed OXA-resistant (OR) HCC cells and used multiple methods, including real-time RT-PCR, Western blot, immunofluorescence, transwell invasion assay, wound-healing assay, MTT assay, gene transfection, and immunohistochemistry to achieve our goals.

Results: We found that OR HCC cells showed a typical epithelial–mesenchymal transition (EMT) phenotype. Meanwhile, the expression of Cx32, a major member of the liver connexin (Cx) family, was lowly expressed in OR HCC cells. Downregulation of Cx32 in parental HCC cells led to EMT induction and thereby reduced OXA cytotoxicity, while Cx32 upregulation in OR HCC cells could reverse the EMT phenotype and partially restore chemosensitivity to OXA. Finally, in human HCC tissue samples, Cx32 was positively correlated with the expression of the EMT marker E-cadherin and negatively correlated with the expression of Vimentin.

Conclusion: Our findings demonstrated that downregulation of Cx32 may be an important determinant for HCC cells to acquire EMT-related acquired drug resistance to OXA, and targeting Cx32 could be a novel strategy to overcome OXA resistance in HCC.

Mechanism for oral tumor cell lysyl oxidase like-2 in cancer development: synergy with PDGF-AB

Extracellular lysyl oxidases (LOX and LOXL1–LOXL4) are critical for collagen biosynthesis. LOXL2 is a marker of poor survival in oral squamous cell cancer. We investigated mechanisms by which tumor cell secreted LOXL2 targets proximal mesenchymal cells to enhance tumor growth and metastasis. This study identified the first molecular mechanism for LOXL2 in the promotion of cancer via its enzymatic modification of a non-collagenous substrate in the context of paracrine signaling between tumor cells and resident fibroblasts. The role and mechanism of active LOXL2 in promoting oral cancer was evaluated and employed a novel LOXL2 small molecule inhibitor, PSX-S1C, administered to immunodeficient, and syngeneic immunocompetent orthotopic oral cancer mouse models. Tumor growth, histopathology, and metastases were monitored. In vitro mechanistic studies with conditioned tumor cell medium treatment of normal human oral fibroblasts were carried out in the presence and absence of the LOXL2 inhibitor to identify signaling mechanisms promoted by LOXL2 activity. Inhibition of LOXL2 attenuated cancer growth and lymph node metastases in the orthotopic tongue mouse models. Immunohistochemistry data indicated that LOXL2 expression in and around tumors was decreased in mice treated with the inhibitor. Inhibition of LOXL2 activity by administration of PXS-S1C to mice reduced tumor cell proliferation, accompanied by changes in morphology and in the expression of epithelial to mesenchymal transition markers. In vitro studies identified PDGFRβ as a direct substrate for LOXL2, and indicated that LOXL2 and PDGF-AB together secreted by tumor cells optimally activated PDGFRβ in fibroblasts to promote proliferation and the tendency toward fibrosis via ERK activation, but not AKT. Optimal fibroblast proliferation in vitro required LOXL2 activity, while tumor cell proliferation did not. Thus, tumor cell-derived LOXL2 in the microenvironment directly targets neighboring resident cells to promote a permissive local niche, in addition to its known role in collagen maturation.

Association between LINC00657 and miR-106a serum expression levels and susceptibility to colorectal cancer, adenomatous polyposis, and ulcerative colitis in Egyptian population

Colorectal cancer (CRC) represented the second cause of mortality among cancer patients. Long noncoding RNAs and microRNAs (miRNAs) serve as noninvasive biomarkers for CRC surveillance and introduce new therapeutic approaches. LINC00657 and miR-106a expression levels play a pivotal role in CRC. This study included 190 Egyptian subjects, and the expression levels of LINC00657 and miR-106a in serum were measured by using quantitative real-time polymerase chain reaction. We found that upregulation of LINC00657 and downregulation of miR-106a are significantly associated with the development of CRC. Also, a positive correlation was detected between their serum levels. In addition, serum LINC00657 can distinguish adenomatous polyposis (AP) patients and/or ulcerative colitis (UC) patients from controls. Also the miRNA-106a expression level discriminates AP but not UC from healthy individuals. Our study cited new diagnostic biomarkers for CRC, AP, and UC among Egyptians in addition to be noninvasive screening tools for CRC in both healthy subjects and those having precancerous lesions. © 2019 IUBMB Life, 71(9):1322-1335, 2019.

Paracrine Induction of Epithelial-Mesenchymal Transition Between Colorectal Cancer Cells and its Suppression by a p53/miR-192/215/NID1 Axis

BACKGROUND & AIMS

Intratumor heterogeneity is a common feature of colorectal cancer (CRC). Here, we analyzed whether mesenchymal-like CRC cells promote the progression of epithelial-like CRC cells via paracrine mechanisms.

METHODS

Six CRC cell lines that show an epithelial phenotype were treated with conditioned media (CM) from CRC cell lines that show a mesenchymal phenotype, and effects on epithelial-mesenchymal transition (EMT), migration, invasion, and chemoresistance were determined. Secreted factors potentially mediating these effects were identified by using cytokine arrays. Associations of these factors with tumor progression and patient survival were determined.

RESULTS

CM obtained from mesenchymal-like CRC cells induced EMT associated with increased migration, invasion, and chemoresistance in epithelial-like CRC cell lines. Notably, activation of p53 in mesenchymal-like CRC cells prevented these effects of CM. Increased concentrations of several cytokines were identified in CM from mesenchymal-like CRC cell lines and a subset of these cytokines showed repression by p53. The down-regulation of nidogen-1 (NID1) was particularly significant and was owing to p53-mediated induction of microRNA-192 and microRNA-215, which directly target the NID1 messenger RNA. NID1 was found to be required and sufficient for inducing EMT, invasion, and migration in epithelial-like CRC cells. In primary CRCs, increased NID1 expression was associated with p53 mutation and microRNA-192/215 down-regulation. Importantly, increased NID1 expression in CRCs correlated with enhanced tumor progression and poor patient survival.

CONCLUSIONS

Taken together, our results show that CRC cells promote tumor progression via secreting NID1, which induces EMT in neighboring tumor cells. Importantly, the interference of p53 with this paracrine signaling between tumor cells may critically contribute to tumor suppression.

Rottlerin inhibits cell growth and invasion via down-regulation of EZH2 in prostate cancer

Rottlerin as a natural agent, which is isolated from Mallotus philippinensis, has been identified to play a critical role in tumor inhibition. However, the molecular mechanism of rottlerin-mediated anti-tumor activity is still ambiguous. It has been reported that EZH2 exhibits oncogenic functions in a variety of human cancers. Therefore, inhibition of EZH2 could be a promising strategy for the treatment of human cancers. In this study, we aim to explore whether rottlerin could inhibit tumorigenesis via suppression of EZH2 in prostate cancer cells. Multiple approaches such as FACS, Transwell invasion assay, RT-PCR, Western blotting, and transfection were performed to determine our aim. We found that rottlerin treatment led to inhibition of cell growth, migration and invasion, but induction of apoptosis in prostate cancer cells. Importantly, we defined that rottlerin decreased the expression of EZH2 and H3K27me3 in prostate cancer cells. Moreover, overexpression of EZH2 abrogated the rottlerin-induced inhibition of cell growth, migration, and invasion in prostate cancer cells. Consistently, down-regulation of EZH2 enhanced rottlerin-triggered anti-tumor function. Collectively, our work demonstrated that rottlerin exerted its tumor suppressive function via inhibition of EZH2 expression in prostate cancer cells. Our findings indicated that rottlerin might be a potential therapeutic compound for treating patients with prostate cancer.

Non-coding RNA in drug resistance of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has been one of the most highly lethal cancers. The acquisition of drug resistance accounts for the majority of poor effects of chemotherapy in HCC. Non-coding RNAs (ncRNAs) including miRNAs, long ncRNAs (lncRNAs), and circular RNA (circRNA) have been well-documented to participate in cancer occurrence and progression. Recently, multiple studies have highlighted the key roles of ncRNAs in chemoresistance of HCC. In addition, accumulating evidence has demonstrated that they can serve as biomarkers in diagnosis, treatment, and prognosis of HCC. In this review, we first overviewed up-to-date findings regarding miRNA and lncRNA in drug resistance of HCC, then summarized specific mechanisms that they modulate chemoresistance of HCC, and finally discussed their potential clinical application in overcoming the obstacle of HCC chemoresistance in the future.

The Network of Non-coding RNAs in Cancer Drug Resistance

Non-coding RNAs (ncRNAs) have been implicated in most cellular functions. The disruption of their function through somatic mutations, genomic imprinting, transcriptional and post-transcriptional regulation, plays an ever-increasing role in cancer development. ncRNAs, including notorious microRNAs, have been thus proposed to function as tumor suppressors or oncogenes, often in a context-dependent fashion. In parallel, ncRNAs with altered expression in cancer have been reported to exert a key role in determining drug sensitivity or restoring drug responsiveness in resistant cells. Acquisition of resistance to anti-cancer drugs is a major hindrance to effective chemotherapy and is one of the most important causes of relapse and mortality in cancer patients. For these reasons, non-coding RNAs have become recent focuses as prognostic agents and modifiers of chemo-sensitivity. This review starts with a brief outline of the role of most studied non-coding RNAs in cancer and then highlights the modulation of cancer drug resistance via known ncRNAs based mechanisms. We identified from literature 388 ncRNA-drugs interactions and analyzed them using an unsupervised approach. Essentially, we performed a network analysis of the non-coding RNAs with direct relations with cancer drugs. Within such a machine-learning framework we detected the most representative ncRNAs-drug associations and groups. We finally discussed the higher integration of the drug-ncRNA clusters with the goal of disentangling effectors from downstream effects and further clarify the involvement of ncRNAs in the cellular mechanisms underlying resistance to cancer treatments.

Knockdown of TWIST enhances the cytotoxicity of chemotherapeutic drugs in doxorubicin-resistant HepG2 cells by suppressing MDR1 and EMT

The transcription factor twist family bHLH transcription factor 1 (TWIST), which is a member of the basic helix-loop-helix class of proteins, is known to induce epithelial-mesenchymal transition (EMT) and promote cancer metastasis. TWIST has previously been reported to be associated with multidrug resistance (MDR), since its depletion increases drug sensitivity. Although these previous studies have established a strong association between EMT and MDR, the molecular mechanism remains obscure. The present study demonstrated that TWIST protein expression was elevated in liver cancer, and was positively correlated with multidrug resistance protein 1 (MDR1) expression. Conversely, MDR1 was negatively correlated with E‑cadherin expression in liver cancer samples. In addition, the present study indicated that doxorubicin-resistant HepG2 (R‑HepG2) cells acquired an EMT phenotype. TWIST was also more highly expressed in R‑HepG2 cells compared with in parental HepG2 cells. Knockdown of TWIST increased the sensitivity of R‑HepG2 cells to 5-fluroracil, cisplatin and doxorubicin through a reduction in MDR1 expression and drug efflux ability. Furthermore, knockdown of TWIST in R‑HepG2 cells inhibited the migratory ability of cells and suppressed the EMT phenotype. These findings demonstrated that targeting TWIST may be considered a novel strategy to overcome drug resistance in liver cancer.

miR-106a Reduces 5-Fluorouracil (5-FU) Sensitivity of Colorectal Cancer by Targeting Dual-Specificity Phosphatases 2 (DUSP2)

BACKGROUND 5-Fluorouracil (5-FU)-based chemotherapy is a conventional therapeutic approach for the treatment of patients with colorectal cancer (CRC). However, development of 5-FU resistance frequently occurs. We explored a potential method for regulating the sensitivity to 5-FU-based chemotherapy in CRC patients. MATERIAL AND METHODS Cell viability was determined by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay. Gene expression levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Protein expression levels were evaluated by Western blot. TargetScan was used for the prediction of binding sites for miRNA in mRNAs. The interaction between mRNA 3'UTR and miRNA was verified by dual luciferase reporter assay. Tissue samples were obtained from 33 CRC patients who received surgery at Xingtai People's Hospital. RESULTS miR-106a level was associated with 5-FU sensitivity in CRC cells. Overexpression of miR-106a reduced 5-FU sensitivity of HCT116 and SW620 cells, and antagonist of miR-106a sensitized HCT116 and SW620 towards 5-FU. miR-106a overexpression decreased dual-specificity phosphatases 2 (DUSP2) expression at mRNA and protein levels in HCT116 and SW620 cells. Through downregulation of DUSP2, miR-106a elevation increased COX-2 expression and stemness-maintenance genes (SOX2 and OCT4). Furthermore, we predicted that miR-106a directly binds to 3'UTR of DUSP2 mRNA, which was confirmed by dual luciferase assay. Silencing of DUSP2 reversed elevated 5-FU sensitivity induced by miR-106a antagonist in HCT116 cells. A negative correlation was discovered between miR-106a and DUSP2 in tumor samples of CRC patients. CONCLUSIONS miR-106a plays an important role in mediating response to 5-FU-based chemotherapy in CRC and could serve as a potential target for CRC patients.

Epithelial-mesenchymal-transition-inducing transcription factors: new targets for tackling chemoresistance in cancer?

Chemoresistance remains a major complication of cancer treatments. Recent data provide strong evidence that chemoresistance is linked to epithelial-mesenchymal transition (EMT), a latent developmental process, which is re-activated during cancer progression. EMT involves transcriptional reprogramming and is driven by specific EMT transcription factors (EMT-TFs). In this review, we provide support for the idea that EMT-TFs contribute to the development of resistance against cancer therapy and discuss how EMT-TFs might be targeted to advance novel therapeutic approaches to the treatment of cancer.

Expression of miR-106 in endometrial carcinoma RL95-2 cells and effect on proliferation and invasion of cancer cells

Expression of miR-106 in endometrial carcinoma RL95-2 cell line and its effect on proliferation and invasion of cancer cells was investigated. miR-106 expression vector was constructed and transiently transfected into in vitro cultured RL95-2 cells of human endometrial carcinoma. Cells were divided into three groups including blank control cells (MOCK group), miR-106 transfection group (miR-106 group) and negative control group (siNC group). Reverse-transcription quantitative PCR (RT-qPCR) was used to detect the expression of miR-106. Proliferation and in vitro migration of RL95-2 cells were detected by MTT and scratch assay, and cell apoptosis was detected by flow cytometry. Compared with MOCK and siNC group, cell apoptosis rate was significantly decreased but cell proliferation rate was significantly increased in miR-106 group (p<0.05). In addition, cell migration and invasion ability was significantly increased in miR-106 group (p<0.05). Overexpression of miR-106 can promote proliferation and inhibit apoptosis of endometrial cancer RL95-2 cells, and miR-106 may serve as a new target for the treatment of endometrial cancer in the future.

Functional Role of Non-Coding RNAs during Epithelial-To-Mesenchymal Transition

Epithelial-to-mesenchymal transition (EMT) is a key biological process involved in a multitude of developmental and pathological events. It is characterized by the progressive loss of cell-to-cell contacts and actin cytoskeletal rearrangements, leading to filopodia formation and the progressive up-regulation of a mesenchymal gene expression pattern enabling cell migration. Epithelial-to-mesenchymal transition is already observed in early embryonic stages such as gastrulation, when the epiblast undergoes an EMT process and therefore leads to the formation of the third embryonic layer, the mesoderm. Epithelial-to-mesenchymal transition is pivotal in multiple embryonic processes, such as for example during cardiovascular system development, as valve primordia are formed and the cardiac jelly is progressively invaded by endocardium-derived mesenchyme or as the external cardiac cell layer is established, i.e., the epicardium and cells detached migrate into the embryonic myocardial to form the cardiac fibrous skeleton and the coronary vasculature. Strikingly, the most important biological event in which EMT is pivotal is cancer development and metastasis. Over the last years, understanding of the transcriptional regulatory networks involved in EMT has greatly advanced. Several transcriptional factors such as Snail, Slug, Twist, Zeb1 and Zeb2 have been reported to play fundamental roles in EMT, leading in most cases to transcriptional repression of cell⁻cell interacting proteins such as ZO-1 and cadherins and activation of cytoskeletal markers such as vimentin. In recent years, a fundamental role for non-coding RNAs, particularly microRNAs and more recently long non-coding RNAs, has been identified in normal tissue development and homeostasis as well as in several oncogenic processes. In this study, we will provide a state-of-the-art review of the functional roles of non-coding RNAs, particularly microRNAs, in epithelial-to-mesenchymal transition in both developmental and pathological EMT.

Diagnostic and prognostic value of miR-106a in colorectal cancer

We sought to systematically evaluate the diagnostic and prognostic value miR106a in patients with colorectal cancer (CRC). An original study was conducted to explore correlations between tissue miR106a levels and outcomes for 138 patients diagnosed with CRC. To explore the diagnostic performance of miR106a, eligible studies were identified from medical databases from China and abroad. Based on these results, 15 studies (including our original study) were pooled and included in a meta-analyses. The pooled sensitivity, specificity, and diagnostic odds ratios of miR106a were 0.53 (95% confidence interval (CI): 0.49–0.57), 0.85 (95% CI: 0.82–0.88), and 7.22 (95% CI: 3.17–16.44) for diagnosis of CRC, and the area under the curve (AUC) for miR106a when diagnosing CRC was 0.72. Patients with higher expression of tissue miR106a had poor overall survival (pooled hazard ratio (HR): 1.50; 95% CI: 1.02–2.20), but not disease-free survival (pooled HR: 1.03; 95% CI: 0.40–2.65). Overexpression of miR106a may predict superior metastasis-free survival (pooled HR: 0.65; 95% CI: 0.33–1.27), but the effect was not significant in this study (p = 0.21).

Rottlerin exerts its anti-tumor activity through inhibition of Skp2 in breast cancer cells

Studies have investigated the tumor suppressive role of rottlerin in carcinogenesis. However, the molecular mechanisms of rottlerin-induced anti-tumor activity are largely unclear. Skp2 (S-phase kinase associated protein 2) has been validated to play an oncogenic role in a variety of human malignancies. Therefore, inactivation of Skp2 could be helpful for the treatment of human cancers. In the current study, we explore whether rottlerin could inhibit Skp2 expression, leading to inhibition of cell growth, migration and invasion in breast cancer cells. We found that rottlerin treatment inhibited cell growth, induced apoptosis and cell cycle arrest. We also revealed that rottlerin suppressed cell migration and invasion in breast cancer cells. Mechanically, we observed that rottlerin significantly down-regulated the expression of Skp2 in breast cancer cells. Importantly, overexpression of Skp2 abrogated rottlerin-mediated tumor suppressive activity, whereas down-regulation of Skp2 enhanced rottlerin-triggered anti-tumor function. Strikingly, we identified that rottlerin exhibited its anti-tumor potential partly through inactivation of Skp2 in breast cancer. Our findings indicate that rottlerin could be a potential safe agent for the treatment of breast cancer.

Downregulation of miR-101 contributes to epithelial-mesenchymal transition in cisplatin resistance of NSCLC cells by targeting ROCK2

Chemoresistance and epithelial-mesenchymal transition (EMT) in cancer are linked phenomena. EMT contributes to chemoresistance, however, little is known about whether chemotherapy can induce EMT in cancer cells. Here, we found that miR-101 expression was downregulated in cisplatin-resistant non-small cell lung cancer (NSCLC) cells. Restoration of miR-101 expression inhibited EMT and increased the sensitivity of cisplatin-resistant NSCLC cells to cisplatin in vitro by targeting ROCK2. Furthermore, ROCK2 protein level was inversely correlated with miR-101 level in NSCLC tissue samples. Kaplan-Meier analysis revealed that low miR-101 expression in NSCLC was correlated with poor survival time. In summary, our results provide novel mechanistic insights into the role of miR-101/ROCK2 signaling in the cisplatin resistance of NSCLC cells. Targeting of miR-101 is a potential therapeutic approach for NSCLC.

Effects of Estrogen and Estrogen Receptors on Transcriptomes of HepG2 Cells: A Preliminary Study Using RNA Sequencing

Men have a much higher incidence of hepatocellular carcinoma (HCC), the predominant form of liver cancer, than women, suggesting that estrogens play a protective role in liver cancer development and progression. To begin to understand the potential mechanisms of estrogens' inhibitory effects on HCC development, RNA sequencing was used to generate comprehensive global transcriptome profiles of the human HCC-derived HepG2 cell line following treatment of vehicle (control), estradiol (E2), estrogen receptor alpha- (ERα-) specific agonist 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT), or ERβ-specific agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN) using a small set of cells. Gene ontology (GO) analysis identified increased expression of genes involved in the biological process (BP) of response to different stimuli and metabolic processes by E2 and ER agonists, which enhanced molecular function (MF) in various enzyme activities and chemical bindings. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional pathway analysis indicated enhanced pathways associated with carbohydrate metabolism, complement and coagulation cascades, and HIF-1 signaling pathway by E2 and ER agonists. GO analysis also identified decreased expression of genes by E2, PPT, and DPN involved in BP related to the cell cycle and cell division, which reduced MF in activity of multiple enzymes and microtubule activity. KEGG analysis indicated that E2, PPT, and DPN suppressed pathways associated with the cell cycle; E2 and PPT suppressed pathways associated with chemical carcinogenesis and drug metabolism, and DPN suppressed DNA replication, recombination, and repair. Collectively, these differentially expressed genes across HepG2 cell transcriptome involving cellular and metabolic processes by E2 and ER agonists provided mechanistic insight into protective effects of estrogens in HCC development.

Knockdown of CMTM3 promotes metastasis of gastric cancer via the STAT3/Twist1/EMT signaling pathway

CMTM3 (CKLF-like MARVEL transmembrane domain containing 3) possesses tumor suppressor properties in multiple types of malignancies. Restoration of CMTM3 significantly inhibits the metastasis of gastric cancer, and its expression level is correlated with prognosis. However, the physiological effects and the mechanism of CMTM3 remain unknown. Here, we suppress CMTM3 expression by shRNA to explore its endogenous effects and its mechanism of action in gastric cancer. Stable knockdown of CMTM3 promotes cell migration, invasion and tumor metastasis, increases MMP2 expression and enhances MMP2 activity. CMTM3 inhibits EMT along with the upregulation of E-cadherin and the downregulation of N-cadherin, Vimentin and Twist1. It has no obvious effects on Zeb1 and Snail. CMTM3 suppresses the phosphorylation of STAT3 but not Akt. More importantly, the EMT phenotype and cell migration induced by CMTM3 knockdown can be reversed by the Jak2/STAT3 inhibitor JSI-124 or by siRNA against STAT3 or Twist1. Overall, this study demonstrates that knockdown of CMTM3 promotes the metastasis of gastric cancer through the STAT3/Twist1/EMT pathway.

Multiple biological functions of Twist1 in various cancers

Twist1 is a well-known regulator of transcription during embryonic organogenesis in many species. In humans, Twist1 malfunction was first linked to Saethre-Chotzen syndrome and later identified to play an essential role in tumor initiation, stemness, angiogenesis, invasion, metastasis, and chemo-resistance in a variety of carcinomas, sarcomas, and hematological malignances. In this review, we will first focus on systematically elaborating the diverse pathological functions of Twist1 in various cancers, then delineating the intricate underlying network of molecular mechanisms, based on which we will summarize current therapeutic strategies in cancer treatment that target and modulate Twist1-involved signaling pathways. Most importantly, we will put special emphasis on revealing the independence and interdependency of these multiple biological functions of Twist1, piecing together the whole delicate picture of Twist1's diversified pathological roles in different cancers and providing new perspectives to guide future research.

Hippo pathway contributes to cisplatin resistant-induced EMT in nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a kind of head-neck malignant tumor derived from the nasopharyngeal epithelium and is mainly prevalent in Southern China and Southeast Asia countries. Cisplatin (DDP) provides the first-line therapeutic administration in NPC patients. However, chemoresistance has been a main barrier and caused bad treatment outcome in NPC therapy. To understand the molecular mechanism of acquired resistance to DDP, multiple methods were performed to examine the morphocytology and molecular changes in DDP-resistant NPC cells. We found that drug resistance cells displayed epithelial-mesenchymal transition (EMT) characteristics. DDP-resistant NPC cells exhibited enhanced migration and invasion potential. Moreover, overexpression of TAZ, one key gene in Hippo pathway, is closely associated with the DDP resistance of NPC cells and its EMT properties. Depletion of TAZ in DDP-resistant cells reversed EMT phenotypes to MET characteristics and restored chemosensitivity of DDP-resistant cells to DDP treatment. These results suggest that inactivation of TAZ could be a promising approach for the treatment of NPC patients.

Recent progress on the effects of microRNAs and natural products on tumor epithelial-mesenchymal transition

Epithelial–mesenchymal transition (EMT) is a biological process of phenotypic transition of epithelial cells that can promote physiological development as well as tissue healing and repair. In recent years, cancer researchers have noted that EMT is closely related to the occurrence and development of tumors. When tumor cells undergo EMT, they can develop enhanced migration and local tissue invasion abilities, which can lead to metastatic growth. Nevertheless, two researches in NATURE deny its necessity in specific tumors and that is discussed in this review. The degree of EMT and the detection of EMT-associated marker molecules can also be used to judge the risk of metastasis and to evaluate patients’ prognosis. MicroRNAs (miRNAs) are noncoding small RNAs, which can inhibit gene expression and protein translation through specific binding with the 3′ untranslated region of mRNA. In this review, we summarize the miRNAs that are reported to influence EMT through transcription factors such as ZEB, SNAIL, and TWIST, as well as some natural products that regulate EMT in tumors. Moreover, mutual inhibition occurs between some transcription factors and miRNAs, and these effects appear to occur in a complex regulatory network. Thus, understanding the role of miRNAs in EMT and tumor growth may lead to new treatments for malignancies. Natural products can also be combined with conventional chemotherapy to enhance curative effects.

miR-106a suppresses tumor cells death in colorectal cancer through targeting ATG7

Autophagy-related gene 7 (ATG7) and miR-106a play an important role in cancer cell autophagy and apoptosis, but the outcome of ATG7 and miR-106a in colorectal cancer (CRC) still remains not clear. In this study, we found that ATG7 and miR-106a expression were mutually related with cell death and prognosis in CRC patients. In addition, we also showed that ATG7 and miR-106a expression were changeable in colorectal cancer cell lines when compared with normal cell lines, but ATG7 and miR-106a mRNA level was negatively correlated. Furthermore, ATG7 protein and mRNA levels decreased after over-expression of miR-106a, whereas the suppression of ATG7 had the opposite effect. We confirmed that miR-106a down-regulated ATG7 mRNA level by binding the specific sequence of ATG7 mRNA 3'UTR region. Moreover, the over-expression of ATG7 induced CRC cells death both in vitro and in vivo. Taken together, our study data demonstrated that ATG7 aggravated the cell death of CRC, which was inhibited by miR-106a.

MiR-30b-5p acts as a tumor suppressor, repressing cell proliferation and cell cycle in human hepatocellular carcinoma

MicroRNAs have been verified to participate in various biological behaviors of different tumors, via multiple signaling pathways. Many kinds of microRNAs in hepatocellular carcinoma have been researched. However, miR-30b-5p hasn't been included. Our study aim at the impacts of miR-30b-5p on HCC and the pathway it mediating. The results showed miR-30b-5p was significant downregulated in HCC tissues and cell lines. With clinical data, we've discovered miR-30b-5p was correlated with several clinical pathological characteristics, such as survival time, tumor size, HBV infected, pathological stage, differentiation and intrahepatic metastasis. Also we illustrated miR-30b-5p repressed cell proliferation and cell cycle of HCC cell lines. For a further study, we figured out that miR-30b-5p mediated DNMT3A to repress proliferation, meanwhile it targeted USP37 for decelerating cell cycle. This discovery inferred miR-30b-5p a potential favorable biomarker and therapeutic target for HCC diagnosis and treatment.

Influence of microRNAs and Long Non-Coding RNAs in Cancer Chemoresistance

Innate and acquired chemoresistance exhibited by most tumours exposed to conventional chemotherapeutic agents account for the majority of relapse cases in cancer patients. Such chemoresistance phenotypes are of a multi-factorial nature from multiple key molecular players. The discovery of the RNA interference pathway in 1998 and the widespread gene regulatory influences exerted by microRNAs (miRNAs) and other non-coding RNAs have certainly expanded the level of intricacy present for the development of any single physiological phenotype, including cancer chemoresistance. This review article focuses on the latest research efforts in identifying and validating specific key molecular players from the two main families of non-coding RNAs, namely miRNAs and long non-coding RNAs (lncRNAs), having direct or indirect influences in the development of cancer drug resistance properties and how such knowledge can be utilised for novel theranostics in oncology.

Role of epithelial to mesenchymal transition in hepatocellular carcinoma

The epithelial to mesenchymal transition (EMT) is a multistep biological process whereby epithelial cells change in plasticity by transient de-differentiation into a mesenchymal phenotype. EMT and its reversal, mesenchymal to epithelial transition (MET), essentially occur during embryogenetic morphogenesis and have been increasingly described in fibrosis and cancer during the last decade. In carcinoma progression, EMT plays a crucial role in early steps of metastasis when cells lose cell-cell contacts due to ablation of E-cadherin and acquire increased motility to spread into surrounding or distant tissues. Epithelial plasticity has become a hot issue in hepatocellular carcinoma (HCC), as strong inducers of EMT such as transforming growth factor-β are able to orchestrate both fibrogenesis and carcinogenesis, showing rising cytokine levels in cirrhosis and late stage HCC. In this review, we consider the significance of EMT-MET in malignant hepatocytes as well as changes in the plasticity of hepatic stellate cells for cellular heterogeneity of HCC, and further aim at explaining the current limiting insights into EMT by snapshot analyses of HCC tissues. Recent advances in the identification of clinically relevant mechanisms that impinge on important EMT-transcription factors, as well as on miRNAs causing EMT signatures and HCC progression are highlighted. In addition, we draw particular attention to framing EMT in the context of potential clinical relevance for HCC patients. We conclude that some aspects of EMT are still elusive and further studies are required to better link the clinical management of HCC with biomarkers and targeted therapies related to EMT.

PDGF-D/PDGFRβ promotes tongue squamous carcinoma cell (TSCC) progression via activating p38/AKT/ERK/EMT signal pathway

Platelet-derived growth factor D (PDGF-D) signaling plays significant roles during the development and progression of human malignancies via interacting with the receptor of PDGF-D (PDGFR). Meanwhile, the majority of human tumor metastasis is closely associated with epithelial-mesenchymal transition (EMT). However, the underlying mechanism between PDGF-D/PDGFR signaling and EMT which involved in tumor metastasis remain dismal. This study aimed to investigate the role of PDGF-D signaling during EMT process of tongue squamous cell carcinoma (TSCC). In our study, the expression of PDGF-D and PDGFR were examined in primary TSCC samples and the expression of PDGF-D was also determined in TSCC cell lines. In addition, the correlation between PDGF-D expression and TSCC aggressive histopathological features was analyzed. Our results implied that upregulation of PDGFRβ in UM1 cells induced with exogenous PDGF-D can remarkably promote tumor cells invasiveness; conversely, when using small interfering RNA (siRNA), the invasiveness can be severely prohibited. Furthermore, PDGF-D downstream signal molecules p38, AKT, ERK and EMT biomarkers (E-cadherin, N-cadherin, Vimentin and snail) were measured using Western blot. Our results showed that PDGF-D can induce p38, AKT and ERK phosphorylation; downregulate epithelial markers and upregulate mesenchymal markers. On the contrary, PDGFRβ siRNA significantly prohibited p38, AKT and ERK phosphorylation; inhibited EMT process. Function analysis revealed that PDGFRβ siRNA obviously interfered with UM1 cell migration and invasion, according to transwell and wound healing assay. In conclusion, this study suggested that EMT process can be triggered by the PDGF-D/PDGFRβ axis in TSCC, and then involved in the tumor cell invasion via activation of p38/AKT/ERK/EMT pathway.

Targeting Epithelial-Mesenchymal Transition (EMT) to Overcome Drug Resistance in Cancer

Epithelial–mesenchymal transition (EMT) is known to play an important role in cancer progression, metastasis and drug resistance. Although there are controversies surrounding the causal relationship between EMT and cancer metastasis, the role of EMT in cancer drug resistance has been increasingly recognized. Numerous EMT-related signaling pathways are involved in drug resistance in cancer cells. Cells undergoing EMT show a feature similar to cancer stem cells (CSCs), such as an increase in drug efflux pumps and anti-apoptotic effects. Therefore, targeting EMT has been considered a novel opportunity to overcome cancer drug resistance. This review describes the mechanism by which EMT contributes to drug resistance in cancer cells and summarizes new advances in research in EMT-associated drug resistance.

EMMPRIN Down-regulating miR-106a/b Modifies Breast Cancer Stem-like Cell Properties via Interaction with Fibroblasts Through STAT3 and HIF-1α

Extracellular matrix metalloproteinase inducer (EMMPRIN) is a heavily glycosylated protein and expresses in cancer cells widely, which plays important roles in tumor progression. However, the role of EMMPRIN in breast cancer stem-like cell properties by interaction with fibroblasts is not known. In the present study, we investigated the effects of fibroblasts on breast cancer stem-like cells. We found that fibroblasts activated by co-cultured breast cancer cells produced higher levels of EMMPRIN, which stimulated the stem-like cell specific, self-renewal and sphere-forming phenotype in breast cancer cells. Increased EMMPRIN expression in activated fibroblasts increased the expression of STAT3 and HIF-1α and showed cancer stem-like cell features in breast cancer cells. We also found that EMMPRIN could down-regulate miR-106a and miR-106b expression in breast cancer cells, which led to activating STAT3 and enhancing HIF-1α expression. Our results illustrated that EMMPRIN has an important role in breast cancer stem-like cells by activation STAT3/HIF-1α through interaction with cancer cells and fibroblasts. The study for the first time indicated that cancer cells and fibroblasts interaction promotes breast cancer cells showing stem-like cells through up-regulation EMMPRIN, and led to inhibiting miR-106a/b expression which targets both STAT3 and HIF-1α expression.

Epithelial-mesenchymal transition and related signaling pathways in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common forms of liver cancer and the third leading cause of cancer-related mortality in the world. Although numerous therapeutic strategies have been employed to treat this fatal disease, the prognosis of HCC patients remains dismal with a low 5-year survival rate of approximately 30%. Postoperative recurrence and metastasis of HCC are the leading cause of poor prognosis. Metastasis has been thought to rely on non-motile epithelial tumor cells acquiring characteristics of mesenchymal cells, which are more migratory. This change is known as the epithelial-to-mesenchymal transition (EMT). EMT has been considered one of the main reasons for the invasion and metastasis of HCC. Notably, increasing evidence indicates that several signaling pathways participate in the regulation of EMT in HCC. In the current review, we will discuss the current progress in research of EMT and its related signaling pathways in HCC.

Twist1-related miR-26b-5p suppresses epithelial-mesenchymal transition, migration and invasion by targeting SMAD1 in hepatocellular carcinoma

Twist1 is well known to induce epithelial-mesenchymal transition (EMT) and promote tumor metastasis. MicroRNAs (miRNAs) are involved in the EMT process and are associated with metastasis in hepatocellular carcinoma (HCC). In the present study, microRNA-26b-5p (miR-26b-5p) expression was consistently and significantly downregulated in HepG2-Twist1 HCC cell lines compared with HepG2-vector cell lines using microarrays (the HepG2-Twist1 cell line can stably express Twist1). miR-26b- 5p downregulation was directly mediated by Twist1 through binding to the promoter region of miR-26b-5p in HepG2-Twist1 cells by ChIP-seq technology. Both gain- and loss-of-function studies showed that miR-26b-5p dramatically suppressed EMT and the invasion ability of HCC cells in vitro. Using mouse models, tumors derived from miR- 26b-5p-overexpressed HCC cells exhibited a significant reduction in tumorigenicity compared with the control group. Subsequent investigation revealed that miR-26b-5p directly inhibited SMAD family member 1 (SMAD1) expression. miR-26b-5p repressed BMP4/Smad1 signaling following SMAD1 inhibition. Overexpression of SMAD1 reversed the function of miR-26b-5p. In human HCC tissues and mouse xenograft tumors, miR-26b-5p levels were inversely correlated with SMAD1 expression as well as metastasis.

CONCLUSION

miR-26b-5p suppresses Twist1-induced EMT, invasion, and metastasis of HCC cells by targeting SMAD1 and BMP4/Smad1 signaling. This suggests a promising application for miR-26b-5p in anti-HCC therapy.