Chemoresistance to gemcitabine in hepatoma cells induces epithelial-mesenchymal transition and involves activation of PDGF-D pathway

The Potential for Natural Products to Overcome Cancer Drug Resistance by Modulation of Epithelial-Mesenchymal Transition

The acquisition of resistance and ultimately disease relapse after initial response to chemotherapy put obstacles in the way of cancer therapy. Epithelial-mesenchymal transition (EMT) is a biologic process that epithelial cells alter to mesenchymal cells and acquire fibroblast-like properties. EMT plays a significant role in cancer metastasis, motility, and survival. Recently, emerging evidence suggested that EMT pathways are very important in making drug-resistant involved in cancer. Natural products are gradually emerging as a valuable source of safe and effective anticancer compounds. Natural products could interfere with the different processes implicated in cancer drug resistance by reversing the EMT process. In this review, we illustrate the molecular mechanisms of EMT in the emergence of cancer metastasis. We then present the role of natural compounds in the suppression of EMT pathways in different cancers to overcome cancer cell drug resistance and improve tumor chemotherapy. HighlightsDrug-resistance is one of the obstacles to cancer treatment.EMT signaling pathways have been correlated to tumor invasion, metastasis, and drug-resistance.Various studies on the relationship between EMT and resistance to chemotherapy agents were reviewed.Different anticancer natural products with EMT inhibitory properties and drug resistance reversal effects were compared.

UDP-glucose dehydrogenase expression is upregulated following EMT and differentially affects intracellular glycerophosphocholine and acetylaspartate levels in breast mesenchymal cell lines

Metabolic rewiring is one of the indispensable drivers of epithelial-mesenchymal transition (EMT) involved in breast cancer metastasis. In this study, we explored the metabolic changes during spontaneous EMT in three separately established breast EMT cell models using a proteomics approach supported by metabolomic analysis. We identified common proteomic changes, including in the expression of CDH1, CDH2, VIM, LGALS1, SERPINE1, PKP3, ATP2A2, JUP, MTCH2, RPL26L1 and PLOD2. Consistently altered metabolic enzymes included: FDFT1, SORD, TSTA3 and UDP-glucose dehydrogenase (UGDH). Of these, UGDH was most prominently altered and has previously been associated with breast cancer patient survival. siRNA-mediated knockdown of UGDH resulted in delayed cell proliferation and dampened invasive potential of mesenchymal cells, and downregulated expression of the EMT transcription factor SNAI1. Metabolomic analysis revealed that siRNA-mediated knockdown of UGDH decreased intracellular glycerophosphocholine (GPC), whereas levels of acetylaspartate (NAA) increased. Finally, our data suggested that platelet-derived growth factor receptor beta (PDGFRB) signaling was activated in mesenchymal cells. siRNA-mediated knockdown of PDGFRB downregulated UGDH expression, potentially via NFkB-p65. Our results support an unexplored relationship between UGDH and GPC, both of which have previously been independently associated with breast cancer progression.

Platelet-Derived Growth Factor Receptor-α Subunit Targeting Suppresses Metastasis in Advanced Thyroid Cancer In Vitro and In Vivo

Thyroid cancer is the most common endocrine malignancy. Patients with well-differentiated thyroid cancers, such as papillary and follicular cancers, have a favorable prognosis. However, poorly differentiated thyroid cancers, such as medullary, squamous and anaplastic advanced thyroid cancers, are very aggressive and insensitive to radioiodine treatment. Thus, novel therapies that attenuate metastasis are urgently needed. We found that both PDGFC and PDGFRA are predominantly expressed in thyroid cancers and that the survival rate is significantly lower in patients with high PDGFRA expression. This finding indicates the important role of PDGF/PDGFR signaling in thyroid cancer development. Next, we established a SW579 squamous thyroid cancer cell line with 95.6% PDGFRA gene insertion and deletions (indels) through CRISPR/Cas9. Protein and invasion analysis showed a dramatic loss in EMT marker expression and metastatic ability. Furthermore, xenograft tumors derived from PDGFRA gene-edited SW579 cells exhibited a minor decrease in tumor growth. However, distant lung metastasis was completely abolished upon PDGFRA gene editing, implying that PDGFRA could be an effective target to inhibit distant metastasis in advanced thyroid cancers. To translate this finding to the clinic, we used the most relevant multikinase inhibitor, imatinib, to inhibit PDGFRA signaling. The results showed that imatinib significantly suppressed cell growth, induced cell cycle arrest and cell death in SW579 cells. Our developed noninvasive apoptosis detection sensor (NIADS) indicated that imatinib induced cell apoptosis through caspase-3 activation. In conclusion, we believe that developing a specific and selective targeted therapy for PDGFRA would effectively suppress PDGFRA-mediated cancer aggressiveness in advanced thyroid cancers.

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.

CENP-A overexpression promotes distinct fates in human cells, depending on p53 status

Tumour evolution is driven by both genetic and epigenetic changes. CENP-A, the centromeric histone H3 variant, is an epigenetic mark that directly perturbs genetic stability and chromatin when overexpressed. Although CENP-A overexpression is a common feature of many cancers, how this impacts cell fate and response to therapy remains unclear. Here, we established a tunable system of inducible and reversible CENP-A overexpression combined with a switch in p53 status in human cell lines. Through clonogenic survival assays, single-cell RNA-sequencing and cell trajectory analysis, we uncover the tumour suppressor p53 as a key determinant of how CENP-A impacts cell state, cell identity and therapeutic response. If p53 is functional, CENP-A overexpression promotes senescence and radiosensitivity. Surprisingly, when we inactivate p53, CENP-A overexpression instead promotes epithelial-mesenchymal transition, an essential process in mammalian development but also a precursor for tumour cell invasion and metastasis. Thus, we uncover an unanticipated function of CENP-A overexpression to promote cell fate reprogramming, with important implications for development and tumour evolution.

Overexpression of PRC1 indicates a poor prognosis in ovarian cancer

Protein regulator of cytokinesis-1 (PRC1) is a microtubule-associated factor involved in cytokinesis. Recent studies have indicated that PRC1 overexpression is involved in tumorigenesis in multiple types of human cancer. However, the expression, biological functions and the prognostic significance of PRC1 in ovarian cancer have not yet been clarified. In this study, it was confirmed that the PRC1 mRNA and protein expression levels were upregulated in high-grade serous ovarian carcinoma (HGSOC) tissues, particularly in patients without breast cancer susceptibility gene (BRCA) pathogenic mutations. PRC1 overexpression contributed to drug resistance, tumor recurrence and a poor prognosis. The findings also indicated that PRC1 knockdown decreased the proliferation, metastasis and multidrug resistance of ovarian cancer cells in vitro. It was also demonstrated that forkhead box protein M1 (FOXM1) regulated the mRNA and protein expression of PRC1. Dual-luciferase reporter assay and rescue assay confirmed that PRC1 was a direct crucial downstream target of FOXM1. On the whole, the findings of this study confirmed that PRC1 was a major prognostic factor of HGSOC and a promising therapeutic biomarker for the treatment of ovarian cancer.

Effect of Chemotherapeutic Agents on the Expression of Retinoid Receptors and Markers of Cancer Stem Cells and Epithelial-Mesenchymal Transition

A large body of evidence suggests that cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT), as well as expression and function of retinoid receptors, are pivotal features of tumor initiation, progression, and chemoresistance. This is also true for pancreatic ductal adenocarcinoma (PDAC), which represents a clinical challenge due to poor prognosis and increasing incidence. Understanding the above features of cancer cells could open new avenues for PDAC treatment strategies. The aim of this study was to investigate the relation between CSCs, EMT, and retinoid receptors in PDAC after treatment with the chemotherapeutic agents - gemcitabine and 5-fluorouracil. First, we demonstrated the difference in the expression levels of CSC and EMT markers and retinoid receptors in the untreated Mia PaCa-2 and Panc1 cells that also differed in the frequency of spontaneous apoptosis and distribution between the cell cycle phases. Chemotherapy reduced the number of cancer cells in the S phase. Gemcitabine and 5-fluorouracil modulated expression of CSC markers, E-cadherin, and RXRβ in Panc1 but not in Mia PaCa-2 cells. We suggest that these effects could be attributed to the difference in the basal levels of expression of the investigated genes. The obtained data could be interesting in the context of future preclinical research.

Sema4C mediates EMT inducing chemotherapeutic resistance of miR-31-3p in cervical cancer cells

Sema4C, the target of many miRNAs, is involved in EMT-mediated chemotherapeutic resistance of many malignant tumors. However, the underlying upstream regulatory mechanisms of Sema4C-induced EMT and Sema4C-mediated drug resistance are still unclear. The aim of this study was to explore the potential role of miR-31-3p/Sema4C in regulating EMT in cisplatin-resistant (CR) cervical cancer cells. High expression levels of Sema4C were more frequently found in cervical cancer tissues and were associated with poor prognosis, whereas miR-31-3p was significantly downregulated in cervical cancer tissues, which was associated with shorter disease-free and overall survival. Overexpression of miR-31-3p inhibited malignant behaviors and EMT of cervical cancer cells in vitro. Furthermore, miR-31-3p was identified to directly target Sema4C, and upregulation of miR-31-3p reversed EMT-mediated biological functions, including cisplatin resistance of Sema4C in cervical cancer cells. These results suggest that Sema4C promoted EMT-mediated cisplatin resistance in cervical cancer cells and that this effect was inhibited by overexpression of miR-31-3p. Thus, silencing Sema4C or overexpression of miR-31-3p could be a novel approach to treat drug resistance to chemotherapy in cervical cancers.

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.

Overexpression of P16 reversed the MDR1-mediated DDP resistance in the cervical adenocarcinoma by activating the ERK1/2 signaling pathway

BACKGROUND

To investigate the role of P16 (INK4a)-extracellular signal related kinase 1/2 (ERK1/2) signaling pathway in cisplatin (DDP) resistance induced by multidrug resistance protein 1 (MDR1), also known as P-glycoprotein (P-gp), in cervical adenocarcinoma.

METHODS

A human DDP-resistant HeLa cell line (HeLa/DDP) was constructed using the combination of incremental and intermittent administration of DDP. Cell Counting Kit-8 (CCK-8) assay was used to measure the IC50 and resistance index (RI) of cells. The morphological changes and population doubling time were observed under an inverted microscope. Plate cloning formation assay was performed to evaluate the cell proliferation and tumorigenic ability. Cell invasion and migration were determined by transwell assays. Besides, the expression of P16, phosphorylated extracellular signal related kinase 1 and 2 (pERK1/2), total ERK1/2 and MDR1 were measured using western blot analysis. The ERK-specific inhibitor U0126 and agonist TPA was used to explore the role of ERK.

RESULTS

The DDP-resistant cervical adenocarcinoma HeLa/DDP cell line was successfully established, which showed stronger cell growth, invasion, and migration. In the HeLa/DDP cells, pERK1/2 was downregulated, P-gp was upregulated and P16 was downregulated. Overexpression of P16 led to a significant decrease in the proliferation rate, migration ability, and invasion ability of the HeLa/DDP cells. Furthermore, overexpression of P16 increased and the decreased expression of pERK1/2 and P-gp in the HeLa/DDP cells, respectively. Treatment of HeLa/DDP cells transfected with P16 plasmid with ERK-specific inhibitor U0126 significantly decreased the expression of pERK1/2 and increased the expression of P-gp from 6 h to 48 h. Moreover, after 72 h, the expression of pERK1/2 was up-regulated and the expression of P-gp was inhibited.

CONCLUSION

Overexpression of P16 could partially reverse the MDR1-mediated DDP resistance in the cervical adenocarcinoma by the enhancement of phosphorylation of ERK signaling pathway, which provided a theoretical basis for the treatment of DDP resistance in cervical adenocarcinoma.

PDGF/PDGFR effects in osteosarcoma and the "add-on" strategy

New treatment options for advanced osteosarcoma have remained limited. The platelet-derived growth factor (PDGF)/platelet-derived growth factor receptor (PDGFR) pathway plays an important role in the development and metastasis of osteosarcoma, via either direct autocrine stimulation of tumor cells, or paracrine stimulation on tumor stromal cells. It promotes angiogenesis to overcome hypoxia in the tumor microenvironment, and modulates tumor interstitial fluid pressure to control the influx and efflux of other agents. Targeting the PDGF/PDGFR pathway is a promising therapeutic method to overcome drug resistance and improve patients' outcome in osteosarcoma. Further evidence is needed to define the detailed mechanism. Results from clinical trials using PDGF/PDGFR inhibitor as a single agent were disappointing, both in osteosarcoma and soft tissue sarcoma. However, when combined with other agents, named as "add-on" strategy, a synergistic antitumor effect has been confirmed in soft tissue sarcoma, and should be attempted in osteosarcoma.

How Tumor Cells Choose Between Epithelial-Mesenchymal Transition and Autophagy to Resist Stress-Therapeutic Implications

Tumor cells undergo epithelial-mesenchymal transition (EMT) or macroautophagy (hereafter autophagy) in response to stressors from the microenvironment. EMT ensues when stressors act on tumor cells in the presence of nutrient sufficiency, and mechanistic target of rapamycin (mTOR) appears to be the crucial signaling node for EMT induction. Autophagy, on the other hand, is induced in the presence of nutrient deprivation and/or stressors from the microenvironment with 5' adenosine monophosphate-activated protein kinase (AMPK) playing an important, but not exclusive role, in autophagy induction. Importantly, mTOR and EMT on one hand, and AMPK and autophagy on the other hand, negatively regulate each other. Such regulation occurs at different levels and suggests that, in many instances, these two stress responses are mutually exclusive. Nevertheless, EMT and autophagy are able to interconvert and we suggest that this may depend on spatiotemporal changes in the tumor microenvironment and/or on duration/intensity of the stressor signal(s). Eventually, we propose a three-pronged therapeutic approach aimed at targeting these three major tumor cell populations. First, cytotoxic drugs that act on differentiated and proliferating tumor cells and which, per se, may promote induction of EMT or autophagy in surviving tumor cells. Second, inhibitors of mTOR in order to prevent EMT induction. Third inducers of autophagic cell death (autosis) in order to deplete tumor cells that are constitutively in an autophagic state or are induced to enter an autophagic state in response to antitumor therapy.

PHD-finger domain protein 5A functions as a novel oncoprotein in lung adenocarcinoma

BACKGROUND

PHD-finger domain protein 5A (PHF5A) is a highly conserved small transcriptional regulator also involved in pre-mRNA splicing; however, its biological functions and molecular mechanisms in non-small cell lung cancer (NSCLC) have not yet been investigated. The purpose of this study was to determine the functional relevance and therapeutic potential of PHF5A in lung adenocarcinoma (LAC).

METHODS

The expression of PHF5A in LAC tissues and adjacent non-tumor (ANT) tissues was investigated using immunohistochemistry of a tissue microarray, qRT-PCR, western blot and bioinformatics. The function of PHF5A was determined using several in vitro assays and also in vivo assay by lentiviral vector-mediated PHF5A depletion in LAC cell lines.

RESULTS

PHF5A was highly upregulated in LAC tissues compared with the ANT counterparts, and closely associated with tumor progression and poor patient prognosis. These results were further confirmed by findings of the TCGA database. Moreover, functional studies demonstrated that PHF5A knockdown not only resulted in reduced cell proliferation, increased cell apoptosis, and cell cycle arrest, but also suppressed migration and invasion in LAC cells. PHF5A silencing was also found to inhibit LAC tumor growth in nude mice. Microarray and bioinformatics analyses revealed that PHF5A depletion led to dysregulation of multiple tumor signaling pathways; selected factors in key signaling pathways were verified in vitro.

CONCLUSIONS

The data suggest for the first time that PHF5A is an oncoprotein that contributes to LAC progression by regulating multiple signaling pathways, and may constitute a prognostic factor and potential new therapeutic target in NSCLC.

Volatile oil from Saussurea lappa exerts antitumor efficacy by inhibiting epithelial growth factor receptor tyrosine kinase-mediated signaling pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) treatment remains lack of effective chemotherapeutic drugs, therefore, discovering novel anti-HCC drugs is a very attractive and urgent task. In this study, we reported VOSL (volatile oil from Saussurea lappa root) exhibits potent therapeutic effect on SMMC-7721 xenografts without obvious side effects. In the in vitro experiments, VOSL inhibited HCC cell proliferation by arresting cell cycle at S and G2/M phases, and induced HCC cell apoptosis by activating the Caspase3 pathway. VOSL also decreased the capability of HCC cell migration and invasion through MMP-9 depression. Moreover, mechanistic study indicated that VOSL can act as an epithelial growth factor receptor (EGFR) inhibitor to suppress EGFR activation and then to suppress its downstream MEK/P38 and PI3-K/Akt pathways. These results suggested that VOSL may be a novel anti-HCC drug candidate.

MicroRNA-421 regulated by HIF-1α promotes metastasis, inhibits apoptosis, and induces cisplatin resistance by targeting E-cadherin and caspase-3 in gastric cancer

Hypoxia and dysregulation of microRNAs (miRNAs) have been identified as crucial factors in carcinogenesis. However, the potential mechanisms of HIF-1α and miR-421 in gastric cancer have not been well elucidated. In this study, we found that miR-421 was up-regulated by HIF-1α. Overexpression of miR-421 promoted metastasis, inhibited apoptosis, and induced cisplatin resistance in gastric cancer in vivo and in vitro. E-cadherin and caspase-3 were identified as targets of miR-421. Besides, relative mRNA expression of miR-421 was significantly increased in gastric cancer tumor tissues compared with non-tumor tissues in a cohort of gastric cancer specimens (n=107). The expression of miR-421 was higher in advanced gastric cancers compared with localized ones. Moreover, Kaplan–Meier analysis illustrated that those patients with low levels of miR-421 had a significant longer overall survival (p = 0.006) and time to relapse (p = 0.007). Therefore, miR-421 could serve as an important prognostic marker and a potential molecular target for therapy in gastric cancer.

Acquisition of EGFR TKI resistance and EMT phenotype is linked with activation of IGF1R/NF-κB pathway in EGFR-mutant NSCLC

Epithelial-mesenchymal transition (EMT) is clinically associated with acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) in non-small cell lung cancers (NSCLC). However, the mechanisms promoting EMT in EGFR TKI-resistant NSCLC have not been fully elucidated. Previous studies have suggested that IGF1R signaling is involved in both acquired EGFR TKI resistance in NSCLC and induction of EMT in some types of tumor. In this study, we further explored the role of the IGF1R signaling in the acquisition of EMT phenotype associated with EGFR TKI resistance in mutant-EGFR NSCLC. Compared to gefitinib-sensitive parental cells, gefitinib-resistant (GR) cells displayed an EMT phenotype associated with increased migration and invasion abilities with the concomitant activation of IGF1R and NF-κB p65 signaling. Inhibition of IGF1R or p65 using pharmacological inhibitor or specific siRNA partially restored sensitivity to gefitinib with the concomitant reversal of EMT in GR cells. Conversely, exogenous IGF1 induced both gefitinib resistance and accompanying EMT in parental cells. We also demonstrated that IGF1R could phosphorylate downstream Akt and Erk to activate NF-κB p65. Taken together, our findings indicate that activation of IGF1R/Akt/Erk/NF-κB signaling is linked to the acquisition of EGFR TKI resistance and EMT phenotype in EGFR-mutant NSCLC and could be a novel therapeutic target for advanced NSCLC.

The neuroleptic drug pimozide inhibits stem-like cell maintenance and tumorigenicity in hepatocellular carcinoma

Drug repurposing is currently an important approach for accelerating drug discovery and development for clinical use. Hepatocellular carcinoma (HCC) presents drug resistance to chemotherapy, and the prognosis is poor due to the existence of liver cancer stem-like cells. In this study, we investigated the effect of the neuroleptic agent pimozide to inhibit stem-like cell maintenance and tumorigenicity in HCC. Our results showed that pimozide functioned as an anti-cancer drug in HCC cells or stem-like cells. Pimozide inhibited cell proliferation and sphere formation capacities in HCC cells by inducing G0/G1 phase cell cycle arrest, as well as inhibited HCC cell migration. Surprisingly, pimozide inhibited the maintenance and tumorigenicity of HCC stem-like cells, particularly the side population (SP) or CD133-positive cells, as evaluated by colony formation, sphere formation and transwell migration assays. Furthermore, pimozide was found to suppress STAT3 activity in HCC cells by attenuating STAT3-dependent luciferase activity and down-regulating the transcription levels of downstream genes of STAT3 signaling. Moreover, pimozide reversed the stem-like cell tumorigenic phenotypes induced by IL-6 treatment in HCC cells. Further, the antitumor effect of pimozide was also proved in the nude mice HCC xenograft model. In short, the anti-psychotic agent pimozide may act as a novel potential anti-tumor agent in treating advanced HCC.

The molecular mechanisms of chemoresistance in cancers

Overcoming intrinsic and acquired drug resistance is a major challenge in treating cancer patients because chemoresistance causes recurrence, cancer dissemination and death. This review summarizes numerous molecular aspects of multi-resistance, including transporter pumps, oncogenes (EGFR, PI3K/Akt, Erk and NF-κB), tumor suppressor gene (p53), mitochondrial alteration, DNA repair, autophagy, epithelial-mesenchymal transition (EMT), cancer stemness, and exosome. The chemoresistance-related proteins are localized to extracellular ligand, membrane receptor, cytosolic signal messenger, and nuclear transcription factors for various events, including proliferation, apoptosis, EMT, autophagy and exosome. Their cross-talk frequently appears, such as the regulatory effects of EGFR-Akt-NF-κB signal pathway on the transcription of Bcl-2, Bcl-xL and survivin or EMT-related stemness. It is essential for the realization of the target, individualized and combine therapy to clarify these molecular mechanisms, explore the therapy target, screen chemosensitive population, and determine the efficacy of chemoreagents by cell culture and orthotopic model.

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.

N-peptide of vMIP-Ⅱ reverses paclitaxel-resistance by regulating miRNA-335 in breast cancer

Acquisition of resistance to paclitaxel is one of the most important problems in treatment of breast cancer patients, but the molecular mechanisms underlying sensitivity to paclitaxel remains elusive. Emerging evidence has demonstrated that microRNAs (miRNAs) play important roles in regulation of cell growth, migration and invasion through inhibiting the expression of its target genes. In our previous studies, we have shown that microRNA-335 (miR‑335) decreased obviously between paclitaxel-resistant (PR) and parental breast cancer cells through miRNA microarray. However, the roles of miR‑335 in breast cancer progression and metastasis are still largely unknown. NT21MP was designed and synthesized as an antagonist with CXCR4 to inhibit cellular proliferation and induce apoptosis. Therefore, the aim of this study was to explore the underlying mechanism of miR‑335 and NT21MP in reverse PR in breast cancer cells. In this study, we found that miR‑335 expression is significantly lower in PR MCF‑7 and SKBR-3 cells (MCF‑7/PR and SKBR-3/PR) compared with their parental MCF‑7 and SKBR-3 cells. Functional experiments showed that overexpression of miR‑335 and NT21MP increased the number of apoptosis cells, arrested cells in G0/G1 phase transition, and suppressed cell migration and invasion in vitro. Dual luciferase assays revealed that SETD8 is a direct target gene of miR‑335. Furthermore, miR‑335 markedly inhibited expression of SETD8 via Wnt/β‑catenin signaling and subsequently inhibited the expression of its downstream genes cyclin D1, and c‑Myc. Additionally, ectopic expression of miR‑335 or depletion of its target gene SETD8 could enhance the sensitivity of PR cells to paclitaxel. Taken together, these date elucidated that NT21MP and miR‑335 mediated PR of breast cancer cells partly through regulation of Wnt/β‑catenin signaling pathway. Activation of miR‑335 or inactivation of SETD8 could be a novel approach for the treatment of breast cancer.

Fabrication and Cytotoxicity of Gemcitabine-Functionalized Magnetite Nanoparticles

Nanotechnology has been successfully used for the fabrication of targeted anti-cancer drug carriers. This study aimed to obtain Fe₃O₄ nanoparticles functionalized with Gemcitabine to improve the cytotoxic effects of the chemotherapeutic substance on cancer cells. The (un) functionalized magnetite nanoparticles were synthesized using a modified co-precipitation method. The nanoconjugate characterization was performed by XRD, SEM, SAED and HRTEM; the functionalizing of magnetite with anti-tumor substances has been highlighted through TGA. The interaction with biologic media has been studied by means of stability and agglomeration tendency (using DLS and Zeta Potential); also, the release kinetics of the drug in culture media was evaluated. Cytotoxicity of free-Gemcitabine and the obtained nanoconjugate were evaluated on human BT 474 breast ductal carcinoma, HepG2 hepatocellular carcinoma and MG 63 osteosarcoma cells by MTS. In parallel, cellular morphology of these cells were examined through fluorescence microscopy and SEM. The localization of the nanoparticles related to the cells was studied using SEM, EDX and TEM. Hemolysis assay showed no damage of erythrocytes. Additionally, an in vivo biodistribution study was made for tracking where Fe₃O₄@Gemcitabine traveled in the body of mice. Our results showed that the transport of the drug improves the cytotoxic effects in comparison with the one produced by free Gemcitabine for the BT474 and HepG2 cells. The in vivo biodistribution test proved nanoparticle accumulation in the vital organs, with the exception of spleen, where black-brown deposits have been found. These results indicate that our Gemcitabine-functionalized nanoparticles are a promising targeted system for applications in cancer therapy.

Downregulated connexin32 promotes EMT through the Wnt/β-catenin pathway by targeting Snail expression in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the common malignances in the world and is associated with high mortality and poor prognosis, partly due to early invasion and metastasis. Cx32 has been indicated to be involved in the progression of many cancers including HCC, but its relationship with tumor invasion and metastasis is still controversial. In the present study, the downregulated Cx32 in HCC tissue was found negatively correlated with histological grade and lymph node metastasis. Cx32 regulated HCC migration and invasion in vitro and inhibited tumor metastasis in xenograft models in vivo. We subsequently identified that Cx32 mediated epithelial-mesenchymal transition (EMT) by regulating Snail expression, and the enhanced Snail was due to activation of Wnt/β-catenin signaling in response to Cx32 inhibition. Finally, decreased expression of Cx32 showed strong correlation with loss/reduction of E-cadherin, higher expression of Snail, and nuclear accumulation of β-catenin in HCC tissues. Taken together, our results suggest that Cx32 inhibits HCC invasion and metastasis through Snail-mediated EMT, Cx32 and this signaling pathway molecules may offer potential targets for HCC cancer therapy.

TAZ overexpression is associated with epithelial-mesenchymal transition in cisplatin-resistant gastric cancer cells

Gastric cancer is one of the common malignant diseases. The poor treatment outcome is mainly due to chemotherapeutic resistance. Therefore, it is important to determine the molecular mechanism of drug resistance in gastric cancer. To explore the mechanisms of cisplatin resistance in gastric cancer cells, several approaches were performed including MTT assay, real-time RT-PCR, western blot analysis, migration and invasion assays, wound healing assay, and transfection. We found that cisplatin-resistant (CR) gastric cancer cells acquired epithelial-mesenchymal transition (EMT) phenotype. The CR cells with EMT features obtained higher migratory and invasive activities. Moreover, we observed that TAZ was highly expressed in CR cells. Consistently, depletion of TAZ caused partial reversal of EMT to MET in CR cells. Our results suggest that TAZ plays a pivotal role in CR-induced EMT. Targeting TAZ could be a potential therapeutic strategy for gastric cancer.

NEDD4 is involved in acquisition of epithelial-mesenchymal transition in cisplatin-resistant nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a highly invasive head-neck cancer derived from the nasopharyngeal epithelium, mainly prevalent in southern China and Southeast Asia. Radiotherapy and adjuvant cisplatin (DDP) chemotherapy are standard administrations applied in the treatment of NPC. However, resistance to chemotherapeutic drugs has recently become more common, resulting in worse treatment outcome for NPC therapy. To elucidate the underlying molecular basis of drug resistance to DDP in NPC cells, we examined the morphocytology, cell motility and molecular changes in DDP-resistant NPC cells with respect to epithelial-mesenchymal transition (EMT) features. We found that EMT is closely associated with DDP-induced drug resistance in NPC cells, as DDP-resistant cells displayed morphological and molecular markers changes consistent with EMT. Wound healing and Transwell Boyden chamber assays revealed an enhanced migration and invasion potential in DDP-resistant NPC cells. Mechanistically, upregulation of NEDD4 was observed to relate to EMT in DDP-resistant cells. More importantly, depletion of NEDD4 in resistant cells led to a partial reversion of EMT phenotypes to MET characteristics. These data suggest that NEDD4 is largely involved in EMT features and chemoresistance of NPC cancer cells. NEDD4 could be a novel therapeutic target to overcome drug resistance in successful administrations of NPC.

Cx32 reverses epithelial-mesenchymal transition in doxorubicin-resistant hepatocellular carcinoma

Recently, epithelial-mesenchymal transition (EMT) has been reported to be an important mechanism of drug resistance in numerous types of cancer cells, including hepatocellular carcinoma (HCC). However, the underlying mechanisms remain to be fully elucidated. Connexin (Cx)32 plays a crucial role in hepatocarcinogenesis. The present study investigated the role of Cx32 in the regulation of chemotherapy-induced EMT in HCC. We found that the expression levels of Cx32 and E-cadherin were clearly decreased in HCC tissues compared with the corresponding paracancerous tissues, while the expression level of vimentin was significantly enhanced in HCC tissues. The expression of Cx32 had a strong correlation with the expression of E-cadherin and vimentin. In an in vitro study, a doxorubicin (DOX)-resistant liver cell line HepG2/DOX was established from parental HepG2 cells. The results showed that HepG2/DOX cells acquired EMT characteristics, with a decreased expression level of E-cadherin and an enhanced expression level of vimentin, and possessed high migratory abilities and invasiveness. Meanwhile, Cx32 was significantly decreased in the HepG2/DOX cells. Knockdown of Cx32 by shRNA in HepG2 cells induced EMT, while overexpression of Cx32 converted EMT to mesenchymal-epithelial transition (MET) in the HepG2/DOX cells. These results suggest that Cx32 is an important regulator of DOX-induced EMT in HCC. Cx32 could be considered as a novel target to reverse DOX resistance in HCC.

PDGF-D promotes cell growth, aggressiveness, angiogenesis and EMT transformation of colorectal cancer by activation of Notch1/Twist1 pathway

Platelet-derived growth factor-D (PDGF-D) plays a crucial role in the progression of several cancers. However, its role in colorectal cancer (CRC) remains unclear. Our study showed that PDGF-D was highly expressed in CRC tissues and was positively associated with the clinicopathological features. Down-regulation of PDGF-D inhibited the tumor growth, migration and angiogenesis of SW480 cells in vitro and in vivo. Whereas up-regulation of PDGF-D promoted the malignant behaviors of HCT116 cells. Moreover, PDGF-D up-regulated the expression of Notch1 and Twist1 in CRC cells. In addition, PDGF-D expression promoted Epithelial to mesenchymal transition (EMT), which was accompanied with decreased E-cadherin and increased Vimentin expression. Consistently, PDGF-D, Notch1, and Twist1 are obviously up-regulated in transforming growth factor-beta 1 (TGF-β1) treated HCT116 cells. Since Notch1 and Twist1 play an important role in EMT and tumor progression, we examined whether there is a correlation between Notch1 and Twist1 in EMT status. Our results showed that up-regulation of Notch1 was able to rescue the effects of PDGF-D down-regulation on Twist1 expression in SW480 cells, whereas down-regulation of Notch1 reduced Twist1 expression in HCT116 cells. Furthermore, we found that Twist1 promoted EMT and aggressiveness of CRC cells. These results suggest that PDGF-D promotes tumor growth and aggressiveness of CRC, moreover, down-regulation of PDGF-D inactivates Notch1/Twist1 axis, which could reverse EMT and prevent CRC progression.

miR-25-3p reverses epithelial-mesenchymal transition via targeting Sema4C in cisplatin-resistance cervical cancer cells

Acquisition of epithelial-mesenchymal transition (EMT) has recently been proposed as an important contributor of drug resistance in cervical cancer cells. However, the underlying mechanisms are still unclear. MicroRNAs play a crucial role in regulating EMT. The aim of this study was to explore the potential role of miR-25-3p in regulating EMT in cisplatin-resistant (CR) cervical cancer cells. To this end, we established stable CR cervical cancer cells, HeLa-CR and CaSki-CR, and investigated the function of miR-25-3p in regulating EMT. It is found that CR cervical cancer cells possessed more EMT characteristics and demonstrated higher migratory abilities and invasiveness. miR-25-3p downregulation was also seen in HeLa-CR and CaSki-CR cells. Of note, ectopic expression of miR-25-3p reversed the EMT phenotype and sensitized CR cells to cisplatin via targeting Sema4C. Furthermore, stable overexpression of miR-25-3p in HeLa-CR cells suppressed tumor growth in mice, downregulated Sema4C and Snail, and upregulated E-cadherin compared with the control group. These results suggest that miR-25-3p is an important regulator of cervical cancer EMT and chemoresistance. Thus, upregulation of miR-25-3p could be a novel approach to treat cervical cancers that are resistant to chemotherapy.

Salvianolic acid A reverses the paclitaxel resistance and inhibits the migration and invasion abilities of human breast cancer cells by inactivating transgelin 2

Multidrug resistance and tumor migration and invasion are the major obstacles to effective breast cancer chemotherapy, but the underlying molecular mechanisms remain unclear. This study investigated the potential of transgelin 2 and salvianolic acid A to modulate the resistance and the migration and invasion abilities of paclitaxel-resistant human breast cancer cells (MCF-7/PTX). MCF-7/PTX cells were found to exhibit not only a high degree of resistance to paclitaxel, but also strong migration and invasion abilities. Small interfering RNA-mediated knockdown of TAGLN2 sensitized the MCF-7/PTX cells to paclitaxel, and inhibited their migration and invasion abilities. In addition, we also observed that combined salvianolic acid A and paclitaxel treatment could reverse paclitaxel resistance, markedly inhibit tumor migration and invasion, and suppress the expression of transgelin 2 in MCF-7/PTX cells. These findings indicate that salvianolic acid A can reverse the paclitaxel resistance and inhibit the migration and invasion abilities of human breast cancer cells by down-regulating the expression of transgelin 2, and hence could be useful in breast cancer treatments.

125I-labeled anti-bFGF monoclonal antibody inhibits growth of hepatocellular carcinoma

AIM: To investigate the inhibitory efficacy of ¹²⁵I-labeled anti-basic fibroblast growth factor (bFGF) monoclonal antibody (mAb) in hepatocellular carcinoma (HCC).

METHODS: bFGF mAb was prepared by using the 1G9B9 hybridoma cell line with hybridization technology and extracted from ascites fluid through a Protein G Sepharose affinity column. After labeling with ¹²⁵I through the chloramine-T method, bFGF mAb was further purified by a Sephadex G-25 column. Gamma radiation counter GC-1200 detected radioactivity of ¹²⁵I-bFGF mAb. The murine H22 HCC xenograft model was established and randomized to interventions with control (phosphate-buffered saline), ¹²⁵I-bFGF mAb, ¹²⁵I plus bFGF mAb, bFGF mAb, or ¹²⁵I. The ratios of tumor inhibition were then calculated. Expression of bFGF, fibroblast growth factor receptor (FGFR), platelet-derived growth factor, and vascular endothelial growth factor (VEGF) mRNA was determined by quantitative reverse transcriptase real-time polymerase chain reaction.

RESULTS: The purified bFGF mAb solution was 8.145 mg/mL with a titer of 1:2560000 and was stored at -20 °C. After coupling, ¹²⁵I-bFGF mAb was used at a 1: 1280000 dilution, stored at 4 °C, and its specific radioactivity was 37 MBq/mg. The corresponding tumor weight in the control, ¹²⁵I, bFGF mAb, ¹²⁵I plus bFGF mAb, and ¹²⁵I-bFGF mAb groups was 1.88 ± 0.25, 1.625 ± 0.21, 1.5 ± 0.18, 1.41 ± 0.16, and 0.98 ± 0.11 g, respectively. The tumor inhibition ratio in the ¹²⁵I, bFGF mAb, ¹²⁵I plus bFGF mAb, and ¹²⁵I-bFGF mAb groups was 13.6%, 20.2%, 25.1%, and 47.9%, respectively. Growth of HCC xenografts was inhibited significantly more in the ¹²⁵I-bFGF mAb group than in the other groups (P < 0.05). Expression of bFGF and FGFR mRNA in the ¹²⁵I-bFGF mAb group was significantly decreased in comparison with other groups (P < 0.05). Groups under interventions revealed increased expression of VEGF mRNA (except for ¹²⁵I group) compared with the control group.

CONCLUSION: ¹²⁵I-bFGF mAb inhibits growth of HCC xenografts. The coupling effect of ¹²⁵I-bFGF mAb is more effective than the concomitant use of ¹²⁵I and bFGF mAb.

Synergistic reversal effect of epithelial-to-mesenchymal transition by miR-223 inhibitor and genistein in gemcitabine-resistant pancreatic cancer cells

Emerging studies have demonstrated that EMT phenotype is closely related with tumor progression and drug resistance in a variety of human cancers. Recently, it has been extensively demonstrated that microRNAs (miRNAs) play a pivotal role in regulating EMT. In our previously reports, we have reported that inhibition of miR-223 could reverse EMT phenotype and improve chemotherapeutic drug sensitivity. We also reported that genistein down-regulated miR-223 expression in gemcitabine-resistant (GR) pancreatic cancer cells. Here, we explored whether there was the synergistic effect between miR-223 inhibitor and genistein on cell growth, migration, invasion and reversal of EMT in GR pancreatic cancer. We found that the combination of miR-223 inhibitor and genistein synergistically reduced cell motility and invasion and enhanced gemcitabine sensitivity in GR cells. In addition, we further observed that miR-223 inhibitor and genistein reversed EMT features in GR cells. This study suggests that the combination of miR-223 inhibitor and genistein may be a potential therapeutic strategy for the treatment of pancreatic cancer.

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.

MiR-125b regulates epithelial-mesenchymal transition via targeting Sema4C in paclitaxel-resistant breast cancer cells

Emerging evidence has demonstrated that microRNAs (miRNA) play a critical role in chemotherapy-induced epithelial-mesenchymal transition (EMT) in breast cancer. However, the underlying mechanism of chemotherapy-mediated EMT has not been fully understood. To address this concern, we explored the role of miR-125b in regulation of EMT in stable paclitaxel-resistant (PR) breast cancer cells, namely MCF-7 PR and SKBR3 PR, which have displayed mesenchymal features. Our results illustrated that miR-125b was significantly downregulated in PR cells. Moreover, ectopic expression of miR-125b by its mimics reversed the phenotype of EMT in PR cells. Furthermore, we found that miR-125b governed PR-mediate EMT partly due to governing its target Sema4C. More importantly, overexpression of miR-125b or depletion of Sema4C sensitized PR cells to paclitaxel. These findings suggest that up-regulation of miR-125b or targeting Sema4C could serve as novel approaches to reverse chemotherapy resistance in breast cancers.

MiR-130a-3p regulates cell migration and invasion via inhibition of Smad4 in gemcitabine resistant hepatoma cells

Background

Emerging evidence demonstrates that microRNAs (miRNAs) play an important role in regulation of cell growth, invasion and metastasis through inhibiting the expression of their targets. It has been reported that miR-130a-3p controls cell growth, migration and invasion in a variety of cancer cells. However, it is unclear whether miR-130a-3p regulates epithelial-mesenchymal transition (EMT) in drug resistant cancer cells. Therefore, in the current study, we explore the role and molecular mechanisms of miR-130a-3p in gemcitabine resistant (GR) hepatocellular carcinoma (HCC) cells.

Methods

The real-time RT-PCR was used to measure the miR-130a-3p expression in GR HCC cells compared with their parental cells. The wound healing assay was conducted to determine the cell migratory activity in GR HCC cells treated with miR-130a-3p mimics. The migration and invasion assays were also performed to explore the role of miR-130a-3p in GR HCC cells. Western blotting analysis was used to measure the expression of Smad4, E-cadherin, Vimentin, and MMP-2 in GR HCC cells after depletion of Smad4. The luciferase assay was conducted to validate whether Smad4 is a target of miR-130a-3p. The student t-test was used to analyze our data.

Results

We found the down-regulation of miR-130a-3p in GR HCC cells. Moreover, we validate the Smad4 as a potential target of miR-130a-3p. Furthermore, overexpression of miR-130a-3p suppressed Smad4 expression, whereas inhibition of miR-130a-3p increased Smad4 expression. Consistently, overexpression of miR-130a-3p or down-regulation of Smad4 suppressed the cell detachment, attachment, migration, and invasion in GR HCC cells.

Conclusions

Our findings provide a molecular insight on understanding drug resistance in HCC cells. Therefore, activation of miR-130a-3p or inactivation of Smad4 could be a novel approach for the treatment of HCC.

The PDGF-D/miR-106a/Twist1 pathway orchestrates epithelial-mesenchymal transition in gemcitabine resistance hepatoma cells

Emerging evidence demonstrates that platelet-derived growth factor-D (PDGF-D) plays a critical role in epithelial-mesenchymal transition (EMT) and drug resistance in hepatocellular carcinoma (HCC) cells. However, the underlying mechanism has not been fully elucidated. The objective is to explore the molecular mechanism of PDGF-D-mediated EMT in drug resistance HCC cells. To achieve our goal, we used multiple approaches including Western blotting, real-time RT-PCR, wound healing assay, invasion assay, luciferase activity assay, transfection, and immunohistochemistry. We found that PDGF-D is highly expressed in gemcitabine-resistant (GR) HCC cells. Moreover, PDGF-D markedly inhibited miR-106a expression and subsequently upregulated Twist1 expression. Notably, PDGF-D expression was associated with miR-106a and Twist1 in HCC patients. Our findings provide a possible molecular mechanism for understanding GR chemoresistance in HCC cells. Therefore, inactivation of PDGF-D/Twist or activation of miR-106a could be a novel strategy for the treatment of HCC.

MiRNA-21 induces epithelial to mesenchymal transition and gemcitabine resistance via the PTEN/AKT pathway in breast cancer

Acquisition of gemcitabine resistance in breast cancer has not been fully clarified. Prior studies suggest that miRNAs are important to chemoresistance in solid tumors and we confirmed that miR-21 is involved in the development of gemcitabine resistance. Epithelial-to-mesenchymal transition (EMT) and AKT pathway activation were noted to be important to this resistance as well. PTEN, a direct target gene of miR-21, was significantly downregulated in gemcitabine-resistant breast cancer cells and restoration of PTEN expression blocked miR-21-induced EMT and gemcitabine resistance. Our data offer novel insight into gemcitabine resistance in breast cancer and suggest that miR-21 may be used to predict optimal breast cancer therapy and may be a potential therapeutic target for reversing gemcitabine resistance.

Down-regulation of miR-223 reverses epithelial-mesenchymal transition in gemcitabine-resistant pancreatic cancer cells

Recent studies have demonstrated that acquisition of epithelial-to-mesenchymal transition (EMT) is associated with drug resistance in pancreatic cancer cells; however, the underlying mechanisms are not fully elucidated. Emerging evidence suggests that microRNAs play a crucial role in controlling EMT. The aims of this study were to explore the potential role of miR-223 in governing EMT in gemcitabine-resistant (GR) pancreatic cancer cells. To achieve this goal, real-time reverse transcription-PCR and western blot analysis were used to validate whether GR cells acquired EMT in AsPC-1 and PANC-1 cells. Invasion, migration, and detachment assays were performed to further identify the EMT characteristics in GR cells. The miR-223 inhibitor was used to determine its role in GR-induced EMT. We found that GR cells acquired EMT features, which obtained elongated fibroblastoid morphology, decreased expression of epithelial marker E-cadherin, and up-regulation of mesenchymal markers. Furthermore, we observed that GR cells are associated with high expression of miR-223. Notably, inhibition of miR-223 led to the reversal of EMT phenotype. More importantly, miR-223 governs GR-induced EMT in part due to down-regulation of its target Fbw7 and subsequent upregulation of Notch-1 in pancreatic cancer. Our study implied that down-regulation of miR-223 could be a novel therapy for pancreatic cancer.

Histone deacetylase inhibitor trichostatin A resensitizes gemcitabine resistant urothelial carcinoma cells via suppression of TG-interacting factor

Gemcitabine and cisplatin (GC) has been widely used for advanced and metastatic urothelial carcinoma (UC). However, resistance to this remedy has been noticed. We have demonstrated that increase of TG-interacting factor (TGIF) in specimens is associated with worse prognosis of upper tract UC (UTUC) patients. The roles of TGIF in the gemcitabine resistance of UC were explored. Specimens of 23 locally advanced/advanced stage UTUC patients who received GC systemic chemotherapy after radical nephroureterectomy were collected to evaluate the alterations of TGIF in the resistance to the remedy by using immunohistochemistry. In vitro characterizations of mechanisms mediating TGIF in gemcitabine resistance were conducted by analyzing NTUB1 cells and their gemcitabine-resistant subline, NGR cells. Our results show that increased TGIF is significantly associated with chemo-resistance, poor progression-free survival, and higher cancer-related deaths of UTUC patients. Higher increases of TGIF, p-AKT(Ser473) and invasive ability were demonstrated in NGR cells. Overexpression of TGIF in NTUB1 cells upregulated p-AKT(Ser473) activation, enhanced migration ability, and attenuated cellular sensitivity to gemcitabine. Knockdown of TGIF in NGR cells downregulated p-AKT(Ser473) activation, declined migration ability, and enhanced cellular sensitivity to gemcitabine. In addition, histone deacetylases inhibitor trichostatin A (TSA) inhibited TGIF, p-AKT(Ser473) expression and migration ability. Synergistic effects of gemcitabine and TSA on NGR cells were also demonstrated. Collectively, TGIF contributes to the gemcitabine resistance of UC via AKT activation. Combined treatment with gemcitabine and TSA might be a promising therapeutic remedy to improve the gemcitabine resistance of UC.

A synthetic lethal screen identifies the Vitamin D receptor as a novel gemcitabine sensitizer in pancreatic cancer cells

Overcoming chemoresistance of pancreatic cancer (PCa) cells should significantly extend patient survival. The current treatment modalities rely on a variety of DNA damaging agents including gemcitabine, FOLFIRINOX, and Abraxane that activate cell cycle checkpoints, which allows cells to survive these drug treaments. Indeed, these treatment regimens have only extended patient survival by a few months. The complex microenvironment of PCa tumors has been shown to complicate drug delivery thus decreasing the sensitivity of PCa tumors to chemotherapy. In this study, a genome-wide siRNA library was used to conduct a synthetic lethal screen of Panc1 cells that was treated with gemcitabine. A sublethal dose (50 nM) of the drug was used to model situations of limiting drug availability to PCa tumors in vivo. Twenty-seven validated sensitizer genes were identified from the screen including the Vitamin D receptor (VDR). Gemcitabine sensitivity was shown to be VDR dependent in multiple PCa cell lines in clonogenic survival assays. Sensitization was not achieved through checkpoint override but rather through disrupting DNA repair. VDR knockdown disrupted the cells' ability to form phospho-γH2AX and Rad51 foci in response to gemcitabine treatment. Disruption of Rad51 foci formation, which compromises homologous recombination, was consistent with increased sensitivity of PCa cells to the PARP inhibitor Rucaparib. Thus inhibition of VDR in PCa cells provides a new way to enhance the efficacy of genotoxic drugs.

Overexpression of platelet-derived growth factor receptor alpha promotes tumor progression and indicates poor prognosis in hepatocellular carcinoma

Dysregulation of platelet-derived growth factor receptor alpha (PDGFRα) has been documented in various cancers. However, its role in hepatocellular carcinoma (HCC) remains unknown. We and others have examined that upregulation of PDGFRα might be involved in hepatocarcinogenesis. Here, we report that PDGFRα plays a critical role in HCC progression and prognosis. The expression of PDGFRα was markedly higher in human HCC compared to adjacent liver tissues. Although PDGFRA mRNA was decreased in HCC, PDGF-A mRNA was dramatically increased in HCC. Overexpression of PDGFRα was strongly correlated with microvessel density (MVD) of HCC (p<0.05), as well as macroscopic vascular invasion of the tumors (p<0.05). HCC patients with high PDGFRα expression displayed a shorter overall survival and a higher recurrence rate than those with low PDGFRα expression (p<0.05, respectively). Additionally, stable overexpression of PDGFRα in hepatoma cells promoted cell proliferation, migration, invasion and epithelial-mesenchymal transition in vitro. Similarly, an in vivo assay showed that PDGFRα overexpression in hepatoma cells exhibited remarkably tumorigenic potential in tumor size and weight in vivo, which displayed markedly elevated MVD than controls. Thus, our study provided the evidence that PDGFRα may serve as a candidate prognostic marker and a novel therapeutic target for HCC.

Platelet-derived growth factor (PDGF) signalling in cancer: rapidly emerging signalling landscape

Platelet-derived growth factor (PDGF)-mediated signalling has emerged as one of the most extensively and deeply studied biological mechanism reported to be involved in regulation of growth and survival of different cell types. However, overwhelmingly increasing scientific evidence is also emphasizing on dysregulation of spatio-temporally controlled PDGF-induced signalling as a basis for cancer development. We partition this multi-component review into recently developing understanding of dysregulation PDGF signalling in different cancers, how PDGF receptors are quantitatively controlled by microRNAs. Moreover, we also summarize most recent advancements in therapeutic targeting of PDGFR as evidenced by preclinical studies. Better understanding of the PDGF-induced intracellular signalling in different cancers will be helpful in catalysing the transition from a segmented view of cancer biology to a conceptual continuum.

The iron chelator Dp44mT inhibits hepatocellular carcinoma metastasis via N-Myc downstream-regulated gene 2 (NDRG2)/gp130/STAT3 pathway

Here we showed that hepatocellular carcinoma (HCC) cell lines with high metastatic potential had low levels of NDRG2. The iron chelator Dp44mT up-regulated NDRG2, suppressed epithelial-mesenchymal transition (EMT) and inhibited tumor metastasis in HCC having high metastatic potential. Also Dp44mT attenuated the TGF-β1-induced EMT in HCC having low metastatic potential. In agreement, silencing endogenous NDRG2 with shNDRG2 in HCC cells attenuated the effect of Dp44mT. We showed that the NDRG2/gp130/STAT3 pathway can mediate Dp44mT effects. In agreement, we found that a combination of NDRG2 expression and p-STAT3 levels is a strong predictor of prognosis in HCC patients. We suggest that up-regulation of NDRG2 by Dp44mT is a promising therapeutic approach in HCC.

Republished: Importance of carcinoma-associated fibroblast-derived proteins in clinical oncology

Carcinoma-associated fibroblast (CAF) as prominent cell type of the tumour microenvironment has complex interaction with both the cancer cells and other non-neoplastic surrounding cells. The CAF-derived regulators and extracellular matrix proteins can support cancer progression by providing a protective microenvironment for the cancer cells via reduction of chemotherapy sensitivity. On the other hand, these proteins may act as powerful prognostic markers as well as potential targets of anticancer therapy. In this review, we summarise the clinical importance of the major CAF-derived signals influencing tumour behaviour and determining the outcome of chemotherapy.

Importance of carcinoma-associated fibroblast-derived proteins in clinical oncology

Carcinoma-associated fibroblast (CAF) as prominent cell type of the tumour microenvironment has complex interaction with both the cancer cells and other non-neoplastic surrounding cells. The CAF-derived regulators and extracellular matrix proteins can support cancer progression by providing a protective microenvironment for the cancer cells via reduction of chemotherapy sensitivity. On the other hand, these proteins may act as powerful prognostic markers as well as potential targets of anticancer therapy. In this review, we summarise the clinical importance of the major CAF-derived signals influencing tumour behaviour and determining the outcome of chemotherapy.

Curcumin inhibits cell growth and invasion through up-regulation of miR-7 in pancreatic cancer cells

Accumulating evidence has revealed that a natural compound curcumin exerts its anti-tumor activity in pancreatic cancer. However, the underlying molecular mechanism remains elusive. Recently, miRNAs have been demonstrated to play a crucial role in tumorigenesis, suggesting that targeting miRNAs could be a promising approach for the treatment of human cancers. In this study, we explored whether curcumin regulates miR-7, leading to the inhibition of cell growth, migration and invasion in pancreatic cancer cells. We observed that curcumin suppressed cell growth, migration and invasion, and induced cell apoptosis, which is associated with increased expression of miR-7 and subsequently decreased expression of SET8, one of the miR-7 targets. These findings demonstrated that targeting miR-7 by curcumin could be a novel strategy for the treatment of pancreatic cancer.

Cx43 reverses the resistance of A549 lung adenocarcinoma cells to cisplatin by inhibiting EMT

Cisplatin (CDDP) is one of the standard first-line chemotherapeutic agents for advanced non-small cell lung cancer (NSCLC). Unfortunately, prolonged exposure to CDDP results in acquired resistance which prevents the successful treatment of lung cancer patients. Thus, it is necessary to explore the mechanism underlying the resistance of NSCLC to CDDP. In the present study, a CDDP-resistant human lung cancer cell line A549/CDDP was established from the parental cell line A549. The results demonstrated that A549/CDDP cells acquired an epithelial-mesenchymal transition (EMT) phenotype, with morphological changes including acquisition of a spindle-like fibroblastic phenotype, downregulation of E-cadherin, upregulation of mesenchymal markers (vimentin, Snail and Slug), and increased capability of invasion and migration. Compared with A549 cells, the A549/CDDP cells showed decreased connexin43 (Cx43) expression. Overexpression of Cx43 reversed EMT and CDDP resistance in the A549/CDDP cells. Conversely, knockdown of Cx43 expression by siRNA-Cx43 initiated EMT and induced CDDP insensitivity in A549 cells. In summary, Cx43 reverses CDDP resistance in A549 CDDP-resistant cells by preventing EMT, making Cx43 a possible therapeutic target for lung cancer.

The therapeutic potential of targeting the epithelial-mesenchymal transition in cancer

INTRODUCTION

The process of epithelial-to-mesenchymal transition (EMT) has long been advocated as a process during tumor progression and the acquisition of metastatic potential of human cancers. EMT has also been linked with resistance to cancer therapies.

AREAS COVERED

Basic research has provided evidence connecting EMT to increased invasion, angiogenesis and metastasis of cancer cells. A number of signaling pathways such as notch, wnt, hedgehog and PI3K-AKT, and various other individual factors therein, have been intricately connected to the onset of EMT. Here, we provide latest updates on the evidences that further highlight an association between various signaling pathways and EMT, with a focus on therapeutic targets that may have the potential to reverse EMT.

EXPERT OPINION

Our understanding of EMT and its underlying causes is rapidly evolving and a number of putative targets have been identified. It is crucial, now than ever before, to design novel translational and clinical studies for the benefit of advanced stage cancer patients with metastatic disease.