A proximal activator of transcription in epithelial-mesenchymal transition

miR-200 promotes the mesenchymal to epithelial transition by suppressing multiple members of the Zeb2 and Snail1 transcriptional repressor complexes

The miR-200 family promotes the epithelial state by suppressing the Zeb1/Zeb2 epithelial gene transcriptional repressors. To identify other miR-200-regulated genes, we isolated mRNAs bound to transfected biotinylated miR-200c in mouse breast cancer cells. In all, 520 mRNAs were significantly enriched in miR-200c binding at least twofold. Putative miR-200-regulated genes included Zeb2, enriched 3.5-fold in the pull down. However, Zeb2 knockdown does not fully recapitulate miR-200c overexpression, suggesting that regulating other miR-200 targets contributes to miR-200's enhancement of epithelial gene expression. Candidate genes were highly enriched for miR-200c seed pairing in their 3'UTR and coding sequence and for genes that were downregulated by miR-200c overexpression. Epidermal growth factor receptor and downstream MAPK signaling pathways were the most enriched pathways. Genes whose products mediate transforming growth factor (TGF)-β signaling were also significantly overrepresented, and miR-200 counteracted the suppressive effects of TGF-β and bone morphogenic protein 2 (BMP-2) on epithelial gene expression. miR-200c regulated the 3'UTRs of 12 of 14 putative miR-200c-binding mRNAs tested. The extent of mRNA binding to miR-200c strongly correlated with gene suppression. Twelve targets of miR-200c (Crtap, Fhod1, Smad2, Map3k1, Tob1, Ywhag/14-3-3γ, Ywhab/14-3-3β, Smad5, Zfp36, Xbp1, Mapk12, Snail1) were experimentally validated by identifying their 3'UTR miR-200 recognition elements. Smad2 and Smad5 form a complex with Zeb2 and Ywhab/14-3-3β and Ywhag/14-3-3γ form a complex with Snail1. These complexes that repress transcription assemble on epithelial gene promoters. miR-200 overexpression induced RNA polymerase II localization and reduced Zeb2 and Snail1 binding to epithelial gene promoters. Expression of miR-200-resistant Smad5 modestly, but significantly, reduced epithelial gene induction by miR-200. miR-200 expression and Zeb2 knockdown are known to inhibit cell invasion in in vitro assays. Knockdown of each of three novel miR-200 target genes identified here, Smad5, Ywhag and Crtap, also profoundly suppressed cell invasion. Thus, miR-200 suppresses TGF-β/BMP signaling, promotes epithelial gene expression and suppresses cell invasion by regulating a network of genes.

Regulation of breast cancer stem cell features

Cancer stem cells (CSCs) are rare, tumour-initiating cells that exhibit stem cell properties: capacity of self-renewal, pluripotency, highly tumorigenic potential, and resistance to therapy. Cancer stem cells have been characterised and isolated from many cancers, including breast cancer. Developmental pathways, such as the Wnt/β-catenin, Notch/γ-secretase/Jagged, Shh (sonic hedgehog), and BMP signalling pathways, which direct proliferation and differentiation of normal stem cells, have emerged as major signalling pathways that contribute to the self-renewal of stem and/or progenitor cells in a variety of organs and cancers. Deregulation of these signalling pathways is frequently linked to an epithelial-mesenchymal transition (EMT), and breast CSCs often possess properties of cells that have undergone the EMT process. Signalling networks mediated by microRNAs and EMT-inducing transcription factors tie the EMT process to regulatory networks that maintain "stemness". Recent studies have elucidated epigenetic mechanisms that control pluripotency and stemness, which allows an assessment on how embryonic and normal tissue stem cells are deregulated during cancerogenesis to give rise to CSCs. Epigenetic-based mechanisms are reversible, and the possibility of "resetting" the abnormal cancer epigenome by applying pharmacological compounds targeting epigenetic enzymes is a promising new therapeutic strategy. Chemoresistance of CSCs is frequently driven by various mechanisms, including aberrant expression/activity of ABC transporters, aldehyde dehydrogenase and anti-oncogenic proteins (i.e. BCL2, B-cell lymphoma-2), enhanced DNA damage response, activation of pro-survival signalling pathways, and epigenetic deregulations. Despite controversy surrounding the CSC hypothesis, there is substantial evidence for their role in cancer, and a number of drugs intended to specifically target CSCs have entered clinical trials.

[The epithelial-mesenchymal transition and fibrosis of the renal transplant]

Epithelial-mesenchymal transition (EMT) is a process by which differentiated epithelial cells undergo a phenotypic conversion and acquire a mesenchymal phenotype, including elongated morphology, enhanced migratory and invasion capacity, and greatly increased production of extracellular matrix (ECM) components. This phenomenon plays a pivotal role in embryonic development, wound healing and tissue regeneration. It has also been involved in organ fibrosis. Some studies suggest that following injury, renal tubular epithelial cells undergo reprograming in mesenchymal cells, and thus constitute an important source of de novo myofibroblasts invading the renal interstitium and contributing to fibrosis. However, an increasing number of studies raise doubts about the existence of this process in vivo. The role of EMT in the development of renal fibrosis remains a matter of intense debate and may depend on the model studied. In this review, we describe the role of EMT in the development of fibrosis of renal graft, and then we propose approaches for detecting and treating renal fibrogenesis by targeting TEM.

High levels of KAP1 expression are associated with aggressive clinical features in ovarian cancer

KAP1 is an universal corepressor for Kruppel-associated box zinc finger proteins in both normal and tumor cells. In this study, the biological function and clinical significance of KAP1 expression in ovarian cancer were investigated. Immunohistological staining of KAP1 was evaluated in 111 patients with ovarian epithelial cancer, 15 with ovarian borderline tumor, and 20 normal ovarian tissue. The correlations of KAP1 expression with clinicopathological features were studied. Kaplan-Meier analysis and Cox proportional hazard modeling were used to assess overall survival to analyze the effect of KAP1 expression on the prognosis of ovarian cancer. The positive rates of KAP1 were significantly higher in ovarian epithelial cancer (55.7%) and borderline tumor (20.0%) than in normal ovarian tissue (5.0%) (all p < 0.01). KAP1 expression correlated significantly with clinical stage (χ2 = 14.57, p < 0.0001), pathological grade (χ2 = 6.06, p = 0.048) and metastases (χ2 =10.38, p = 0.001). Patients with high KAP 1 levels showed poor survival (p < 0.0001). Multivariate analysis showed that KAP1 high expression was an independent predictor for ovarian cancer patients (hazard ratio = 0.463; 95% confidence interval = 0.230-0.9318, p = 0.031). Functionally, depletion of KAP1 by siRNA inhibited ovarian cancer cell proliferation, cell migration. KAP1 expression correlated with aggressive clinical features in ovarian cancer. High KAP1 expression was a prognostic factor of ovarian cancer.

KAP-1 is overexpressed and correlates with increased metastatic ability and tumorigenicity in pancreatic cancer

This study aimed to investigate the role in metastasis and prognostic value of KAP-1 in pancreatic cancer (PC). The expression of KAP-1 was analyzed by quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemical staining in 91 human PC tissue samples. Capan-2 cells were transfected with a lentiviral vector expressing KAP-1 (Capan-2/KAP-1) or the empty vector (Capan-2/vector); cell migration and invasion were assayed in vitro using Transwell migration and wound-healing assays, and in vivo using a xenograft model in nude mice. KAP-1 was found to be overexpressed in human PC, and the expression of KAP-1 correlated with clinical stage. Overexpression of KAP-1 increased the invasion and migration of Capan-2 cells in vitro. Furthermore, overexpression of KAP-1 promoted the growth and metastatic ability of PC cells in a xenograft model in nude mice. Moreover, overexpression of KAP-1 induced the epithelial-mesenchymal transition (EMT) in PC cells both in vitro and in vivo, as indicated by increased expression of mesenchymal markers such as vimentin and decreased expression of E-cadherin. This study indicates that KAP-1 may promote metastasis in PC by regulating the EMT and suggests that KAP-1 may have potential as a predictor of metastasis in patients with pancreatic cancer.

Trim28 contributes to EMT via regulation of E-cadherin and N-cadherin in lung cancer cell lines

In previous work, we demonstrated that transcription factor Trim28 (Tripartite motif containing 28) plays a tumor-suppressor role in early-staged adenocarcinoma of the lung due to its ability to restrain transcription of cell cycle-regulating genes. Herein we examine Trim28's role in the epithelial-to-mesenchymal transition (EMT) which is strongly implicated in cancer metastasis. We found that Trim28 plays a role in TGF-β-induced EMT in non-small cell lung cancer cells. Silencing Trim28 with inhibitory RNAs alters the expression of numerous EMT markers, such as E-cadherin and N-cadherin, whereas overexpression of Trim28 has an opposite effect. Trim28 expression is induced following TGF-β treatment at both protein and mRNA levels. Trim28 deficiency impairs TGF-β-induced EMT and decreases cell migration and invasion. Finally, we demonstrate that the expression of Trim28 affects the acetylation and methylation of histones on E-cadherin and N-cadherin promoters. These results suggest that Trim28 contributes to EMT and might be important for tumor metastasis in lung cancer. Taken together with our previous work these results suggest a model in which Trim28 is a tumor suppressor early in the transformation process in lung cancer, but in later stages it functions as an oncogene.

Molecular mechanisms of epithelial-mesenchymal transition

The transdifferentiation of epithelial cells into motile mesenchymal cells, a process known as epithelial-mesenchymal transition (EMT), is integral in development, wound healing and stem cell behaviour, and contributes pathologically to fibrosis and cancer progression. This switch in cell differentiation and behaviour is mediated by key transcription factors, including SNAIL, zinc-finger E-box-binding (ZEB) and basic helix-loop-helix transcription factors, the functions of which are finely regulated at the transcriptional, translational and post-translational levels. The reprogramming of gene expression during EMT, as well as non-transcriptional changes, are initiated and controlled by signalling pathways that respond to extracellular cues. Among these, transforming growth factor-β (TGFβ) family signalling has a predominant role; however, the convergence of signalling pathways is essential for EMT.

MAGEC2, an epithelial-mesenchymal transition inducer, is associated with breast cancer metastasis

MAGEC2 is a member of melanoma antigen (MAGE) family of cancer-testis antigens and associated with tumor relapse and metastasis. Here, we investigated the expression of MAGEC2 in patients with breast cancer and its clinical effects with underlying mechanisms. The expression levels of MAGEC2 were compared between 420 invasive ductal carcinoma (IDC) and 120 ductal carcinoma in situ of the breast. Correlations between MAGEC2 expression and clinico-pathologic factors or survival of patients with IDC were analyzed. In addition, MAGEC2 expression levels in tumor tissues dissected from the primary focus and matched tumor-invaded axillary lymph nodes were analyzed in 8 breast cancer patients. The functional effects of MAGEC2 overexpression were assessed in vitro using scratch assay and transwell chamber assay. MAGEC2 expression was increased in metastatic breast cancer in comparison to the non-metastatic. MAGEC2 expression was significantly associated with ER negative expression (P = 0.037), high tumor grade (P = 0.014) and stage (P = 0.002), high incidence of axillary lymph node metastasis (P = 0.013), and distant metastasis (P = 0.004). Patients with tumor with MAGEC2 positive expression have a worse prognosis and a shorter metastasis free interval. Multivariate analyses showed that MAGEC2 expression was an independent risk factor for patient overall survival and metastasis-free survival. Breast cancer cells that overexpressed MAGEC2 had stronger migratory and invasive potential than control-treated cells. Epithelial markers (E-cadherin and cytokeratin) were down-regulated in MAGEC2-overexpressing cells compared to controls, whereas mesenchymal markers (vimentin and fibronectin) were upregulated. Our results indicate that MAGEC2 has a role in breast cancer metastasis through inducing epithelial-mesenchymal transition. In addition, MAGEC2 is a novel independent poor prognostic factor in patients with IDC. Thus, targeting MAGEC2 may provide a novel therapeutic strategy for breast cancer treatment.

Mechanisms of cellular fibrosis associated with cancer regimen-related toxicities

Fibrosis is a common, persistent and potentially debilitating complication of chemotherapy and radiation regimens used for the treatment of cancer. The molecular mechanisms underlying fibrosis have been well studied and reveal overall processes that are largely ubiquitous. However, it is important to note that although the processes are similar, they result in cellular phenotypes that are highly tissue specific. These tissue specific differences may present opportunities for therapeutic interventions to prevent or treat this often irreversible condition. Data generated from animal models of cancer therapy-related tissue toxicities have revealed that the signaling pathways involved in fibrosis are the same as those involved in the normal injury response and include the transforming growth factor β superfamily and a range of pro-inflammatory cytokines. The critical difference between normal wound healing and fibrosis development appears to be, that in fibrosis, these signaling pathways escape normal cellular regulation. As a result, an injury state is maintained and processes involved in normal healing are usurped. There are a few, if any, therapeutics that effectively prevent or treat fibrosis in patients. Consequently, cancer survivors may be chronically plagued with a variety of life-altering fibrosis-related symptoms. Uncovering the signaling pathways that drive cellular fibrosis is paramount to the development of specific therapeutics that will mitigate this potentially devastating condition.

HNRNPAB induces epithelial-mesenchymal transition and promotes metastasis of hepatocellular carcinoma by transcriptionally activating SNAIL

Expression of heterogeneous nuclear ribonucleoprotein AB (HNRNPAB) has been reported to be dysregulated in tumors, but its specific contributions to tumor formation and progression are not fully understood. Here, we demonstrate that HNRNPAB is overexpressed in highly metastatic cells and tumor tissues from patients with hepatocellular carcinoma (HCC) with recurrence. We found that HNRNPAB overexpression promoted epithelial-mesenchymal transition (EMT) in a manner associated with HCC metastasis in vitro and in vivo. RNA interference-mediated silencing of the EMT factor SNAIL attenuated HNRNPAB-enhanced cell invasion in vitro and lung metastasis in vivo. Mechanistically, HNRNPAB acted to transactivate SNAIL1 transcription, which in turn inhibited transcription of the pivotal SNAIL target gene E-cadherin. Overexpression of HNRNPAB in HCC samples correlated with higher SNAIL levels, shorter overall survival, and higher tumor recurrence. HNRNPAB overexpression, alone or in combination with SNAIL, was found to be a significant independent risk factor for recurrence and survival after curative resection. In conclusion, our findings define HNRNPAB as an activator of EMT and metastasis in HCC that predicts poor clinical outcomes.

Correlation between the overexpression of epidermal growth factor receptor and mesenchymal makers in endometrial carcinoma

Objective

The objective of this study was to evaluate the effect of overexpression of epidermal growth factor receptor (EGFR) on the expression of epithelial cell markers (E-cadherin and α-catenin) and mesenchymal cell markers (N-cadherin and vimentin) in endometrial carcinoma.

Methods

The expression of all 4 markers was evaluated in EGFR overexpressing Ishikawa cells, control Ishikawa cells, and KLE cells using reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. The expression of these 4 markers was also determined in cancerous tissues of patients with endometrial carcinoma using immunohistochemical staining.

Results

Ishikawa cells transfected with EGFR showed decreased expression of E-cadherin and α-catenin and increased expression of N-cadherin and vimentin compared with control Ishikawa cells (p<0.01 for all). The expression of N-cadherin and vimentin was higher and the expression of E-cadherin and α-catenin was lower in stage II-III than stage I and in grade II-III than grade I endometrial carcinoma tissue (p<0.01 for all).

Conclusion

Decreased expression of epithelial markers (E-cadherin and α-catenin) and increased expression of mesenchymal markers (N-cadherin and vimentin) were observed in human endometrial carcinoma tissue. These findings correlate with high EGFR expression in cultured endometrial carcinoma cells.

Identification of key regulators for the migration and invasion of rheumatoid synoviocytes through a systems approach

Rheumatoid synoviocytes, which consist of fibroblast-like synoviocytes (FLSs) and synovial macrophages (SMs), are crucial for the progression of rheumatoid arthritis (RA). Particularly, FLSs of RA patients (RA-FLSs) exhibit invasive characteristics reminiscent of cancer cells, destroying cartilage and bone. RA-FLSs and SMs originate differently from mesenchymal and myeloid cells, respectively, but share many pathologic functions. However, the molecular signatures and biological networks representing the distinct and shared features of the two cell types are unknown. We performed global transcriptome profiling of FLSs and SMs obtained from RA and osteoarthritis patients. By comparing the transcriptomes, we identified distinct molecular signatures and cellular processes defining invasiveness of RA-FLSs and proinflammatory properties of RA-SMs, respectively. Interestingly, under the interleukin-1β (IL-1β)-stimulated condition, the RA-FLSs newly acquired proinflammatory signature dominant in RA-SMs without losing invasive properties. We next reconstructed a network model that delineates the shared, RA-FLS-dominant (invasive), and RA-SM-dominant (inflammatory) processes. From the network model, we selected 13 genes, including periostin, osteoblast-specific factor (POSTN) and twist basic helix-loop-helix transcription factor 1 (TWIST1), as key regulator candidates responsible for FLS invasiveness. Of note, POSTN and TWIST1 expressions were elevated in independent RA-FLSs and further instigated by IL-1β. Functional assays demonstrated the requirement of POSTN and TWIST1 for migration and invasion of RA-FLSs stimulated with IL-1β. Together, our systems approach to rheumatoid synovitis provides a basis for identifying key regulators responsible for pathological features of RA-FLSs and -SMs, demonstrating how a certain type of cells acquires functional redundancy under chronic inflammatory conditions.

Proteomics of differential extraction fractions enriched for chromatin-binding proteins from colon adenoma and carcinoma tissues

BACKGROUND

Altered nuclear and genomic structure and function are hallmarks of cancer cells. Research into nuclear proteins in human tissues could uncover novel molecular processes in cancer. Here, we examine biochemical tissue fractions containing chromatin-binding (CB) proteins in the context of colorectal cancer (CRC) progression.

METHODS

CB protein-containing fractions were biochemically extracted from human colorectal tissues, including carcinomas with chromosomal instability (CIN), carcinomas with microsatellite instability (MIN), and adenomas. The CB proteins were subjected to label-free LC-MS/MS and the data were analyzed by bioinformatics.

RESULTS

Over 1700 proteins were identified in the CB fraction from colonic tissues, including 938 proteins associated with nuclear annotation. Of the latter, 169 proteins were differential between adenomas and carcinomas. In this adenoma-versus-carcinoma comparison, apart from specific changes in components of the splicing and protein translational machineries, we also identified significant changes in several proteins associated with chromatin-directed functions. Furthermore, several key cell cycle proteins as well as those involved in cellular stress were increased, whereas specific components of chromosome segregation and DNA recombination/repair systems were decreased.

CONCLUSIONS

Our study identifies proteomic changes at the subnuclear level that are associated with CRC and may be further investigated. This article is part of a Special Issue entitled: Biomarkers: A Proteomic Challenge.

Claudins 1, 2, 3, 4, 5 and 7 in solar keratosis and squamocellular carcinoma of the skin

Claudins are tight junction proteins regulating the paracellular permeability of cell layers. We investigated the expression of claudins 1, 2, 3, 4, 5 and 7 in a sample set consisting of a total of 93 cases representing normal skin, actinic keratoses and squamous cell carcinomas of the skin. There were several changes found in claudin expression. Claudin 1 appeared to be progressively decreased in solar keratosis and skin squamous cell carcinomas compared to normal skin while expression of claudin 2 was increased. With claudins 3 and 5 occasional immunoreactivity was found in squamous cell carcinomas. Claudins 4 and 7 were variably expressed in skin neoplasia compared to normal skin. According to the results expression of claudins 1 and 2 change in parallel with the severity of the epidermal preneoplastic and neoplastic lesions thus probably influencing the disturbed epithelial polarity characteristic of these lesions. Claudin 1 under- and claudin 2 overexpression also lead to a leakier epithelial barrier function of the skin with a resulting damage to skin epithelial resistance. Other claudins investigated in this study did not show progressive changes even though occasional overexpression of them was found in skin squamous cell carcinoma.

Loss of ZBRK1 contributes to the increase of KAP1 and promotes KAP1-mediated metastasis and invasion in cervical cancer

ZBRK1, a zinc finger protein that interacts with breast cancer 1 (BRCA1) and KRAB-ZFP-associated protein 1 (KAP1), has been suggested to serve as a tumor suppressor via repression of tumor metastasis/invasion. To date, the detailed molecular mechanisms for how BRCA1 and KAP1 participate in ZBRK1-mediated transcriptional repression, metastasis and invasion as well as the associated clinical relevance remain unclear. In this study, we demonstrated that both the N- and C-terminal domains of ZBRK1 are important for inhibiting cell proliferation and anchorage-independent growth in cervical cancer. Specifically, the N-terminal KRAB domain of ZBRK1 displayed a more crucial role in inhibiting metastasis and invasion through modulation of KAP1 function in a transcriptionally dependent manner. The loss of ZBRK1 results in an increase of KAP1 expression, which enhanced migration and invasion of cervical cancer cells both the in vitro and in vivo. Moreover, an inverse correlation of expression levels was observed between ZBRK1 and KAP1 following tumor progression from in situ carcinoma to invasive/metastatic cervical cancer specimens. Taken together, the current results indicate that a loss of ZBRK1 contributes to the increased expression of KAP1, potentiating its role to enhance metastasis and invasion.

Human umbilical cord mesenchymal stem cells attenuate cisplatin-induced acute and chronic renal injury

Mesenchymal stem cell is becoming a promising candidate in acute kidney injury (AKI). We first reported that human umbilical cord mesenchymal stem cells (hucMSCs) could ameliorate renal function in ischemic/reperfusion AKI rats, but the role of hucMSCs in cisplatin-induced acute and chronic injury has been demonstrated. More specifically, it is still unknown whether hucMSCs halt renal interstitial fibrosis. In this study, we investigated the effect of hucMSCs in cisplatin-induced kidney injury and explored the mechanism of action. Blood urea nitrogen (BUN) and creatinine (Cr) analyses showed amelioration of functional parameters in hucMSC-treated rats at early damage. Transplantation with hucMSCs promoted renal cell regeneration, inhibited cell apoptosis, abrogated inflammatory responses and protected mitochondria. Moreover, Masson's trichrome staining demonstrated reduced levels of fibrosis in kidney tissues of hucMSC-treated rats at six and eight weeks after cisplatin injection. These results were corroborated by reduced collagen deposit, the ratio of Bax to Bcl-2 and transforming growth factor β mRNA expression. Furthermore, hucMSCs prevented the epithelial-mesenchymal transition (EMT) in injury renal tissues, leading to the attenuation of chronic renal interstitial fibrosis. Taken together, our findings suggested that hucMSCs could decrease the kidney from development of later renal interstitial fibrosis by amelioration of early AKI.

SiRNA-mediated silencing of KAP-1 expression inhibits invasion of human pancreatic cancer PANC-1 cells

AIM: To investigate the impact of small interfering RNA (siRNA)-mediated KAP-1 gene silencing on invasion of human pancreatic cancer PANC-1 cells, and to explore the feasibility of human KAP-1 gene as a therapeutic target for pancreatic cancer.

METHODS: Five KAP-1-specific siRNAs were designed using online software to construct pGC-LV-siRNA-KAP-1 plasmid. Western blot was used to screen the efficient plasmid in 293T cells, and the most efficient one was packed into the recombinant lentivirus Lv-siRNA-KAP-1 in 293T cells. The titer of lentivirus was determined by hole-by-dilution titer assay. The silencing effect of Lv-siRNA-KAP-1 in PANC-1 cells was validated by real-time PCR. After PANC-1 cells were infected with Lv-siRNA-KAP-1, cell invasion was detected by Transwell chamber assay. Vimentin expression in cells was detected by Western blot.

RESULTS: Four KAP-1-specific siRNAs could silence the expression of KAP-1 at the protein level 48 h after transfection. The most efficient pGC-siRNA-3 plasmid was used to construct Lv-VIM-shRNA. The titer of lentivirus was 2 × 10⁹ TU/mL. KAP-1 knockdown significantly inhibited invasion of human pancreatic cancer PANC-1 cells compared to blank control and negative control cells (97.3 ± 25.6 vs 253.3 ± 20.6, 213.2 ± 19.4, both P < 0.05). The expression of vimentin was down-regulated in PANC-1 cells infected with Lv-siRNA-KAP-1.

CONCLUSION: Lv-siRNA-KAP-1 could effectively inhibit the expression of KAP-1 gene in PANC-1 cells in vitro, cell invasion and Vimentin expression. KAP-1 might serve as a new target for gene therapy of pancreatic cancer.

Honokiol thwarts gastric tumor growth and peritoneal dissemination by inhibiting Tpl2 in an orthotopic model

Honokiol is known to suppress the growth of cancer cells; however, to date, its antiperitoneal dissemination effects have not been studied in an orthotopic mouse model. In the present study, we evaluated the antiperitoneal dissemination potential of Honokiol in an orthotopic mouse model and assessed associations with tumor growth factor-β1 (TGFβ1) and cells stimulated by a carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Our results demonstrate that tumor growth, peritoneal dissemination and peritoneum or organ metastasis of orthotopically implanted MKN45 cells were significantly decreased in Honokiol-treated mice and that endoplasmic reticulum (ER) stress was induced. Honokiol-treated tumors showed increased epithelial signatures such as E-cadherin, cytokeratin-18 and ER stress marker. In contrast, decreased expression of vimentin, Snail and tumor progression locus 2 (Tpl2) was also noted. TGFβ1 and MNNG-induced downregulation of E-cadherin and upregulation of Tpl2 were abrogated by Honokiol treatment. The effect of Tpl2 inhibition in cancer cells or endothelial cells was associated with inactivation of CCAAT/enhancer binding protein B, nuclear factor kappa-light-chain-enhancer of activated B cell and activator protein-1 and suppression of vascular endothelial growth factor. Inhibition of Tpl2 in gastric cancer cells by small interfering RNA or pharmacological inhibitor was found to effectively reduce growth ability and vessel density in vivo. Honokiol-induced reversal of epithelial-to-mesenchymal transition (EMT) and ER stress-induced apoptosis via Tp12 may involve the paralleling processes. Taken together, our results suggest that the therapeutic inhibition of Tpl2 by Honokiol thwarts both gastric tumor growth and peritoneal dissemination by inducing ER stress and inhibiting EMT.

Relationship between epithelial and stromal TRIM28 expression predicts survival in colorectal cancer patients

BACKGROUND AND AIM

TRIM28 is a multi-domain nuclear protein with pleotropic effects in both normal and tumor cells. In this study, TRIM28 expression in epithelial and stromal tumor microenvironment and its prognostic role in colorectal cancer were investigated.

METHODS

Immunohistological staining of TRIM28 was evaluated in tissue microarrays constructed from 137 colorectal cancer patients. The correlations of TRIM28 expression with clinicopathological features and p53 expression were studied. Kaplan-Meier analysis and Cox proportional hazard modeling were used to assess overall survival (OS) and recurrence-free survival (RFS).

RESULTS

Strong epithelial TRIM28 expression was found in 42% of colorectal cancer tissues. TRIM28 expression correlated significantly with p53 expression in matched cases (P=0.0168, Spearman rank test). A high epithelial to stromal TRIM28 expression ratio was associated with shorter OS (P=0.033; log-rank test) and RFS (P=0.043; log-rank test). Multivariate analysis showed that the epithelial to stromal TRIM28 expression ratio was an independent predictor of OS (hazard ratio=2.136; 95% confidence interval 1.015-4.498, P=0.046) and RFS (hazard ratio=2.100; confidence interval 1.052-4.191, P=0.035).

CONCLUSION

A high TRIM28 expression ratio between stromal and epithelial compartments in colorectal cancer tissue is an independent predictor of poor prognosis. The pathophysiological role of TRIM28 in carcinogenesis may be dependent on expression levels and cell type within the tumor microenvironment.

Paricalcitol attenuates 4-hydroxy-2-hexenal-induced inflammation and epithelial-mesenchymal transition in human renal proximal tubular epithelial cells

4-Hydroxy-2-hexenal (HHE), the aldehyde product of lipid peroxidation, may be responsible for the pathogenesis of progressive renal disease. Recently, paricalcitol (19-nor-1,25-dihydroxyvitamin D2) was shown to be renoprotective through its anti-inflammatory and antifibrotic effects in various experimental nephropathy models. In this study, we investigated the effects of paricalcitol on inflammation and epithelial-mesenchymal transition (EMT) after HHE-induced renal tubular epithelial cell injury. To investigate the molecular mechanisms underlying HHE-induced renal tubular cell injury, the human proximal tubular epithelial (HK-2) cells cultured with 10 µM HHE in the presence or absence of paricalcitol. In HK-2 cells, paricalcitol attenuated the HHE-induced expression of extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase, and prevented nuclear factor-κB (NF-κB) activation. The expression of the inflammatory proteins inducible nitric oxide synthase and cyclooxygenase-2 was attenuated by paricalcitol pretreatment. In addition, HHE increased the expression of the transforming growth factor (TGF)-β/Smad signaling proteins and fibrotic proteins, such as α-smooth muscle actin and connective tissue growth factor; this inducible expression was suppressed by pretreatment with paricalcitol. Treatment with HHE resulted in the activation of the β-catenin signaling pathway, and paricalcitol pretreatment reduced the expression of β-catenin in HHE-treated HK-2 cells. Coimmunoprecipitation shows that paricalcitol induced vitamin D receptor (VDR)/β-catenin complex formation in HK-2 cells. Also immunofluorescence staining revealed that co-localization of VDR and β-catenin in the nuclei. ICG-001, an inhibitor of β-catenin, decreased the expression of TGF-β1 and attenuated HHE-induced tubular EMT. These results show that paricalcitol attenuated HHE-induced renal tubular cell injury by suppressing inflammation and EMT process through inhibition of the NF-κB, TGF-β/Smad, and β-catenin signaling pathways.

Clinical significance of expression of KAP-1 in pancreatic carcinoma

AIM: To investigate the expression of KAP-1 in pancreatic carcinoma.

METHODS: The expression of KAP-1 protein in 46 pancreatic cancer specimens (including 15 cases of highly differentiated cancer, 17 cases of moderately differentiated cancer, and 14 cases of poorly differentiated cancer) and 9 normal pancreas specimens was detected by immunohistochemistry. The mRNA and protein expression of KAP-1 in 8 cases of pancreatic cancer and matched tumor-adjacent pancreatic tissue and in pancreatic carcinoma cell lines (BxPC3, CAPAN-1, PANC-1, AsPC-1, SW1990, MiaPaCa-2 and CFPAC-1) was also detected by RT-qPCR and Western blot.

RESULTS: The positive rate of KAP-1 expression was 45.6% (21/46) in pancreatic cancer and 11.1% (1/9) in normal pancreatic tissue, and was 78.6% (11/14) in poorly differentiated pancreatic cancer, 47.1% (8/17) in moderately differentiated pancreatic cancer, and 13.3% (2/15) in highly differentiated pancreatic cancer. The mRNA and protein expression of KAP-1 was higher in pancreatic cancer than in matched tumor-adjacent pancreatic tissue. The mRNA expression of KAP-1 was highest in poorly differentiated pancreatic cancer line Panc-1, higher in BXPC-3 and CFPAC-1, lower in SW1990, Capan-1 and MIAPaCa-2, and lowest in AsPC-1 and Capan-2. The protein expression of KAP-1 was highest in poorly differentiated pancreatic cancer line MIAPaCa-2 and Panc-1, higher in CFPAC-1 which is derived from liver metastases of pancreatic cancer cell, and was undetectable in other cell lines.

CONCLUSION: The expression of KAP-1 in human pancreatic cancer tissue is significantly higher than that in normal pancreatic tissue, and KAP-1 expression is involved in pancreatic cancer cell differentiation. KAP-1 may play an important role in the development of pancreatic cancer.

GLIPR-2 overexpression in HK-2 cells promotes cell EMT and migration through ERK1/2 activation

The epithelial-to-mesenchymal transition (EMT) of tubular epithelial cells in the adult kidney is one of the key events in renal interstitial fibrosis. Glioma pathogenesis related-2 (GLIPR-2) has been shown to be up-regulated in proximal tubular cells (PTCs) in the fibrotic kidney. However, the biological function of GLIPR-2 remains unknown. In this study, we found that GLIPR-2 expression is elevated in the kidney tissue samples of patients with diabetic nephropathy (DN). Human proximal renal tubular epithelial cells (HK-2 cells) were transfected with pcDNA3.0-GLIPR-2 and selected with G418. To identify the biological function of GLIPR-2, an epithelial-to-mesenchymal transition (EMT) PCR array analysis was performed, and genes that had statistically significantly altered expression levels with more than a two-fold difference compared with the pcDNA3.0-transfected HK-2 cells were considered. Key elements of the EMT process, such as E-cadherin and vimentin, were transcriptionally activated in the pcDNA3.0-GLIPR-2-transfected sublines. In addition, α-SMA gene expression, which is a marker of myofibroblasts, increased in the pcDNA3.0-GLIPR-2-transfected HK-2 cells. The cell migration assay demonstrated that the transfection of HK-2 with GLIPR-2 promoted cell migration following an EMT. Additionally, consistent with the effects of increased EGFR expression levels, we found that the activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) was highly elevated in the pcDNA3.0-GLIPR-2-transfected group. Our study demonstrates that GLIPR-2 overexpression in HK-2 cells can potentiate EMT-like processes in this cell type through the ERK1/2 signaling pathway. GLIPR-2 may be responsible for the development of renal fibrosis by increasing the accumulation of interstitial fibroblasts.

Quantitative proteomic analysis of differentially expressed proteins in pancreatic cancer stem cells

AIM: To screen and identify differentially expressed proteins in pancreatic cancer stem cells.

METHODS: MIA-PaCa2 (TIC^high) and BxPc-3 (TIC^low) were used in the study. Differentially expressed proteins between MIA-PaCa2 (TIC^high) and BxPc-3 (TI^Clow) cells were isolated and screened by 2D-DIGE analysis. Protein identification was performed by peptide mass fingerprinting with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF). Western blot was performed to verify the differential expression of TRIM28.

RESULTS: Fluorescent differential protein expression patterns were obtained between MIA-PaCa2 (TIC^high) and BxPc-3 (TIC^low) cells. Analyses with DeCyder v6.5 software showed a total of 23 differentially expressed protein spots (>1.5 folds), and these protein spots were identified by mass spectrometry as 19 proteins, which are involved in cell communication and signal transduction, immune response, transcription and cell cycle regulation, adipocyte differentiation and lipid droplet formation, cytoskeletal formation, cell adhesion, transport, and translation. Western blot analysis revealed that TRIM28 was highly expressed in MIA-PaCa2 (TIC^high) cells but not expressed in BxPc-3 (TIC^low) cells. Among the 19 identified proteins, 8 were up-regulated and 11 down-regulated in MIA-PaCa2 (TIC^high) cells.

CONCLUSION: The identified differentially expressed proteins, such as TRIM28, are associated with the genesis, development and regulation of pancreatic cancer stem cells. They may become new therapeutic targets for pancreatic cancer.

Identification of KAP-1-associated complexes negatively regulating the Ey and β-major globin genes in the β-globin locus

Deregulations of erythroid differentiation may lead to erythroleukemia and other hemoglobinopathies, yet the molecular mechanisms underlying these events are not fully understood. Here, we found that KAP-1-associated complexes contribute to the regulation of the β-globin locus, the key events of erythroid differentiation. We show that RNAi-mediated knockdown of KAP-1 in mouse erythroleukemia (MEL) cells increases expression of the Ey and β-major globin genes during hexamethylenebisacetamide (HMBA) induced differentiation process. This indicates that at least part of KAP-1-associated complexes negatively regulates β-globin gene expression during definitive erythroid differentiation. ChIP-PCR analysis revealed that one or more KAP-1-associated complexes are targeted to the promoter region of the Ey and beta-major globin genes. Since KAP-1 is only a scaffold molecule, there must be some transcriptional regulators allowing its targeted recruitment to the β-globin locus. To further discover these novel regulators, proteins interacting with KAP-1 were isolated by endogenous immunoprecipitation and identified by LC-ESI-MS/MS. Among the proteins identified, MafK and Zfp445 were studied further. We found that KAP-1 may contribute to the repression of Ey and β-major globin gene transcription through recruitment to the promoters of these two genes, mediated by the interaction of KAP-1 with either Zfp445 or MafK, respectively.

Functional vascular smooth muscle cells derived from human induced pluripotent stem cells via mesenchymal stem cell intermediates

AIMS

Smooth muscle cells (SMC) play an important role in vascular homeostasis and disease. Although adult mesenchymal stem cells (MSC) have been used as a source of contractile SMC, they suffer from limited proliferation potential and culture senescence, particularly when originating from older donors. By comparison, human induced pluripotent stem cells (hiPSC) can provide an unlimited source of functional SMC for autologous cell-based therapies and for creating models of vascular disease. Our goal was to develop an efficient strategy to derive functional, contractile SMC from hiPSC.

METHODS AND RESULTS

We developed a robust, stage-wise, feeder-free strategy for hiPSC differentiation into functional SMC through an intermediate stage of multipotent MSC, which could be coaxed to differentiate into fat, bone, cartilage, and muscle. At this stage, the cells were highly proliferative and displayed higher clonogenic potential and reduced senescence when compared with parental hair follicle mesenchymal stem cells. In addition, when exposed to differentiation medium, the myogenic proteins such as α-smooth muscle actin, calponin, and myosin heavy chain were significantly upregulated and displayed robust fibrillar organization, suggesting the development of a contractile phenotype. Indeed, tissue constructs prepared from these cells exhibited high levels of contractility in response to receptor- and non-receptor-mediated agonists.

CONCLUSION

We developed an efficient stage-wise strategy that enabled hiPSC differentiation into contractile SMC through an intermediate population of clonogenic and multipotent MSC. The high yield of MSC and SMC derivation suggests that our strategy may facilitate an acquisition of the large numbers of cells required for regenerative medicine or for studying vascular disease pathophysiology.

TRIM28, a new molecular marker predicting metastasis and survival in early-stage non-small cell lung cancer

TRIM28 is a universal corepressor for Kruppel-associated box zinc finger proteins. In this study, we demonstrated the expression of TRIM28 gene was significantly higher in cancerous tissues than in noncancerous tissues (P < 0.001). TRIM28 knockdown resulted in a decrease in cell proliferation in liquid media as well as in soft agar. The proliferation rate was impaired and the cell cycle progression was inhibited after knockdown of TRIM28 in non-small cell lung cancer cell lines PAa and SK-MES-1. We used real-time polymerase chain reaction to detect circulating cancer cells in 138 non-small cell lung cancer patients. The overall positive detection rate was 30.4% (42 of 138) in peripheral blood of NSCLC patients and was 29.9% (29 of 97) in early-stage patients. In a 70-month follow-up study, 20 of 29 patients (69.0%) in TRIM28 positive group had recurrence and/or metastasis, significantly higher (P = 0.004) than in the TRIM28 negative group (25 of 68, 36.8%). In addition, non-small cell lung cancer patients whose circulating cancer cells expressed TRIM28 suffered shorter tumor-specific survival compared with those with absent TRIM28 expression (P < 0.001). Results of our study showed that TRIM28 provides a survival advantage to lung cancer cells and may be a new marker to predict metastasis and prognosis in early-stage non-small cell lung cancer patients.

S100A4 in esophageal cancer: Is this the one to blame?

Metastasis is the main reason for cancer-related death. S100A4 is one of the key molecules involved in this event. Several studies have shown that overexpression of S100A4 in non-metastatic cancer cells can make them become metastatic, and knockdown of S100A4 in metastatic cancer cells can curtail their invasive nature. A study by Chen et al^[2] published in the World J Gastroenterol 18(9): 915-922, 2012 is a typical example. This study showed in vitro and in vivo evidence that S100A4 expression level determines the invasiveness of esophageal squamous carcinoma. Considering the fact that more than half of the cancer-related deaths are caused by malignancies derived from the digestive system and esophageal cancer is the 4th top contributor to this fraction, this study warrants more attention.

Cellular and molecular mechanisms of chronic inflammation-associated organ fibrosis

Organ fibrosis is a pathological condition associated with chronic inflammatory diseases. In fibrosis, excessive deposition of extracellular matrix (ECM) severely impairs tissue architecture and function, eventually resulting in organ failure. This process is mediated primarily by the induction of myofibroblasts, which produce large amounts of collagen I, the main component of the ECM. Accordingly, the origin, developmental pathways, and mechanisms of myofibroblast regulation are attracting increasing attention as potential therapeutic targets. The fibrotic cascade, from initial epithelial damage to eventual myofibroblast induction, is mediated by complex biological processes such as macrophage infiltration, a shift from Th1 to Th2 phenotype, and by inflammatory mediators such as transforming growth factor-β. Here, we review the current understanding of the cellular and molecular mechanisms underlying organ fibrosis.

Induction of a mesenchymal expression program in lung epithelial cells by wingless protein (Wnt)/β-catenin requires the presence of c-Jun N-terminal kinase-1 (JNK1)

Recent studies suggest the importance of the transition of airway epithelial cells (EMT) in pulmonary fibrosis, and also indicate a role for Wingless protein (Wnt)/β-catenin signaling in idiopathic pulmonary fibrosis. We investigated the possible role of the Wnt signaling pathway in inducing EMT in lung epithelial cells, and sought to unravel the role of c-Jun-N-terminal-kinase-1 (JNK1). The exposure of C10 lung epithelial cells or primary mouse tracheal epithelial cells (MTECs) to Wnt3a resulted in increases in JNK phosphorylation and nuclear β-catenin content. Because the role of β-catenin as a transcriptional coactivator is well established, we investigated T-cell factor/lymphocyte-enhancement factor (TCF/LEF) transcriptional activity in C10 lung epithelial cells after the activation of Wnt. TCF/LEF transcriptional activity was enhanced after the activation of Wnt, and this increase in TCF/LEF transcriptional activity was diminished after the small interfering (si)RNA-mediated ablation of JNK. The activation of the Wnt pathway by Wnt3a, or the expression of either wild-type or constitutively active β-catenin (S37A), led to the activation of an EMT transcriptome, manifested by the increased mRNA expression of CArG box-binding factor-A, fibroblast-specific protein (FSP)-1, α-smooth muscle actin (α-SMA), and vimentin, increases in the content of α-SMA and FSP1, and the concomitant loss of zona occludens-1. The siRNA-mediated ablation of β-catenin substantially decreased Wnt3a-induced EMT. The siRNA ablation of JNK1 largely abolished Wnt3a, β-catenin, and β-catenin S37a-induced EMT. In MTECs lacking Jnk1, Wnt3a-induced increases in nuclear β-catenin, EMT transcriptome, and the content of α-SMA or FSP1 were substantially diminished. These data show that the activation of the Wnt signaling pathway is capable of inducing an EMT program in lung epithelial cells through β-catenin, and that this process is controlled by JNK1.

[Epithelial-mesenchymal transition and tumor metastasis]

Metastasis is the transfer of malignant tumors from one organ to a distant organ. It is the most common cause of death in cancer patients. Different molecular mechanisms enable tumor cells to infiltrate the surrounding tissue, invade blood vessels and leave the blood stream at a different site. Epithelial-mesenchymal transition (EMT) is critical for appropriate embryonic development, and this process is re-engaged in adults during wound healing, tissue regeneration, organ fibrosis, and cancer progression. EMT is the first step in tumor invasion and metastasis. A detailed knowledge of the molecular requirements for EMT in human cancer will help us to better understand tumor progression and to delineate more effective strategies for future therapeutic intervention.

Effect of 5/6 nephrectomized rat serum on epithelial-to-mesenchymal transition in vitro

Objective: To investigate whether the 5/6 nephrectomized (5/6Nx) rats’ 12-week serum could lead to tubular epithelial-to-mesenchymal transition (EMT) and its molecular mechanism, so as to probe the potential stimulation from circulation in chronic progressive kidney disease. Methods: A total of 24 Sprague Dawley (SD) rats were randomly divided into two groups: sham operation group (sham group) and 5/6Nx group. Rats were killed 12 weeks after surgery to obtain 5/6Nx rats’ 12-week serum. Then we detected the expression of E-cadherin in renal tubular epithelial cells of the remaining kidney and we investigated whether the 12th week serum of 5/6Nx rats could cause HK-2 (human kidney proximal tubular cell line) cells to transdifferentiate into fibroblasts. Results: Our data confirmed that E-cadherin expression decreased significantly in the remaining kidney at 12 weeks, and the 5/6Nx rats’ 12-week serum could suppress E-cadherin protein and mRNA expression (p < 0.05). We also found that the 5/6Nx rats’ 12-week serum could upreg-ulate ZEB1, β-catenin, and wnt3 protein expression (p < 0.05). Conclusions: Our results demonstrated that the 5/6Nx rats’ 12-week serum could suppress the expression of E-cadherin in HK-2 cells. It was partially through modulating the increase of ZEB1. The loss of E-cadherin could lead β-catenin to localize to the cytoplasm and nucleus, and feed into the Wnt signaling pathway. It means that the pathogenic serum in chronic kidney disease (CKD) plays an important role in the loss of renal function and turns to be a new avenue of research with potential clinical implications.

EGFR signaling promotes TGFβ-dependent renal fibrosis

The mechanisms by which angiotensin II (Ang II) promotes renal fibrosis remain incompletely understood. Ang II both stimulates TGFβ signaling and activates the EGF receptor (EGFR), but the relative contribution of these pathways to renal fibrogenesis is unknown. Using a murine model with EGFR-deficient proximal tubules, we demonstrate that upstream activation of EGFR-dependent ERK signaling is critical for mediating sustained TGFβ expression in renal fibrosis. Persistent activation of the Ang II receptor stimulated ROS-dependent phosphorylation of Src, leading to sustained EGFR-dependent signaling for TGFβ expression. Either genetic or pharmacologic inhibition of EGFR significantly decreased TGFβ-mediated fibrogenesis. We conclude that TGFβ-mediated tissue fibrosis relies on a persistent feed-forward mechanism of EGFR/ERK activation through an unexpected signaling pathway, highlighting EGFR as a potential therapeutic target for modulating tissue fibrogenesis.

Transcriptional networks in epithelial-mesenchymal transition

Backround

Epithelial-mesenchymal transition (EMT) changes polarized epithelial cells into migratory phenotypes associated with loss of cell-cell adhesion molecules and cytoskeletal rearrangements. This form of plasticity is seen in mesodermal development, fibroblast formation, and cancer metastasis.

Methods and Findings

Here we identify prominent transcriptional networks active during three time points of this transitional process, as epithelial cells become fibroblasts. DNA microarray in cultured epithelia undergoing EMT, validated in vivo, were used to detect various patterns of gene expression. In particular, the promoter sequences of differentially expressed genes and their transcription factors were analyzed to identify potential binding sites and partners. The four most frequent cis-regulatory elements (CREs) in up-regulated genes were SRY, FTS-1, Evi-1, and GC-Box, and RNA inhibition of the four transcription factors, Atf2, Klf10, Sox11, and SP1, most frequently binding these CREs, establish their importance in the initiation and propagation of EMT. Oligonucleotides that block the most frequent CREs restrain EMT at early and intermediate stages through apoptosis of the cells.

Conclusions

Our results identify new transcriptional interactions with high frequency CREs that modulate the stability of cellular plasticity, and may serve as targets for modulating these transitional states in fibroblasts.

The role of EMT in renal fibrosis

It is clear that the well-described phenomenon of epithelial-mesenchymal transition (EMT) plays a pivotal role in embryonic development, wound healing, tissue regeneration, organ fibrosis and cancer progression. EMTs have been classified into three subtypes based on the functional consequences and biomarker context in which they are encountered. This review will highlight findings on type II EMT as a direct contributor to the kidney myofibroblast population in the development of renal fibrosis, specifically in diabetic nephropathy, the signalling molecules and the pathways involved in type II EMT and changes in the expression of specific miRNA with the EMT process. These findings have provided new insights into the activation and development of EMT during disease processes and may lead to possible therapeutic interventions to suppress EMTs and potentially reverse organ fibrosis.

Epithelial-mesenchymal transition (EMT) in kidney fibrosis: fact or fantasy?

Epithelial-mesenchymal transition (EMT) has become widely accepted as a mechanism by which injured renal tubular cells transform into mesenchymal cells that contribute to the development of fibrosis in chronic renal failure. However, an increasing number of studies raise doubts about the existence of this process in vivo. Herein, we review and summarize both sides of this debate, but it is our view that unequivocal evidence supporting EMT as an in vivo process in kidney fibrosis is lacking.

Scar wars: mapping the fate of epithelial-mesenchymal-myofibroblast transition

The hypothesis that epithelial-mesenchymal transition (EMT) might be a contributor to the accumulation of fibroblasts and myofibroblasts (MFs) in the kidney during fibrogenesis was postulated 15 years ago. This paradigm offered an elegant explanation of how the loss of epithelial functions is coupled to the gain of deleterious mesenchymal functions; for example, excessive matrix deposition. Moreover, it interpreted chronic kidney disease in a developmental context: because the tubular epithelium originates from the metanephric mesenchyme, EMT can be viewed as a dedifferentiation process in response to injury, which might serve healing or--if dysregulated--might facilitate fibrosis. Several observations support the role of EMT in renal fibrosis: (1) Tubular cells can transform to fibroblasts and MFs in vitro. (2) Histological 'snapshots' reveal the coexistence of epithelial and mesenchymal markers in transitioning tubular cells in fibrosis models and human kidney diseases. (3) Early lineage-tracing experiments detected mesenchymal markers in the genetically tagged epithelium. However, the paradigm has been recently challenged; new fate-mapping studies found no evidence for the expression of (myo)fibroblast markers in the epithelium during fibrogenesis. This review summarizes the key findings and caveats, aiming at a balanced view, which neither overestimates the role of the epithelium in MF generation nor denies the importance of epithelial plasticity in fibrogenesis.

The sensors and regulators of cell-matrix surveillance in anoikis resistance of tumors

Normal cells continuously monitor the nature of their respective cellular microenvironment. They are equipped with an inherent molecular defense to detect changes that can precipitate and trigger an oncogenic cascade in the internal and external environment of cells. The process called anoikis unleashes many a characteristic molecular change in the cells which eventually program to cell death in response to cell detachment and inappropriate cellular attachment, both of which can otherwise potentiate the ability of cells to preferentially pursue a malignant course due to the release of molecular discipline which conforms them to a benign structural and functional spectrum. The initiation and propagation of signaling that serves as a switch to cell survival or cell death mediated by surveillance of cell microenvironment is comprised of many heterogeneous sets of molecules interacting mainly at the interface of cell-extracellular matrix. Transforming cells continuously reprogram their signaling characteristics in sensing and modulating the stimuli from cell surface molecules like integrins, cadherins and immunoglobulin family of cell adhesion molecules at adhesion complexes, which enables them to resist anoikis and metastasize to different organs. Actin cytoskeleton binds BIM and Bcl2 modifying factor (BMF), which are regulated by the adhesion status and consequent conformation of cytoskeleton in the cells. This review aims at an integrated synopsis of fundamental mechanisms of the critical interactions of cell surface molecules to facilitate a focused analysis of the differential regulation of signaling processes at cell-ECM junctions that collectively rein the anoikis resistance, which in turn impacts metastatic aggressiveness and drug resistance of tumors originating from respective organs.

Epithelial-mesenchymal interactions in biliary diseases

In most cholangiopathies, liver diseases of different etiologies in which the biliary epithelium is the primary target in the pathogenic sequence, the central mechanism involves inflammation. Inflammation, characterized by pleomorphic peribiliary infiltrate containing fibroblasts, macrophages, lymphocytes, as well as endothelial cells and pericytes, is associated to the emergence of "reactive cholangiocytes." These biliary cells do not possess bile secretory functions, are in contiguity with terminal cholangioles, and are of a less-differentiated phenotype. They have acquired several mesenchymal properties, including motility and ability to secrete a vast number of proinflammatory chemo/cytokines and growth factors along with de novo expression of a rich receptor machinery. These functional properties enable reactive cholangiocytes to establish intimate contacts and to mutually exchange a variety of paracrine signals with the different mesenchymal cell types populating the portal infiltrate. The extensive crosstalk between the epithelial and mesenchymal compartments is the driver of liver repair mechanisms in cholangiopathies, ultimately evolving toward portal fibrosis. Herein, the authors first review the properties of the different cell types involved in their interaction, and then analyze the underlying molecular mechanisms as they relate to liver repair in cholangiopathies.

Tumor initiation and progression in hepatocellular carcinoma: risk factors, classification, and therapeutic targets

Hepatocellular carcinoma (HCC) is a major health problem worldwide responsible for 500 000 deaths annually. A number of risk factors are associated with either the induction of the disease or its progression; these include infection with hepatitis B or C virus, alcohol consumption, non-alcoholic steatohepatitis and certain congenital disorders. In around 80% of the cases, HCC is associated with cirrhosis or advanced fibrosis and with inflammation and oxidative stress. In this review we focus firstly on the different risk factors for HCC and summarize the mechanisms by which each is considered to contribute to HCC. In the second part we look at the molecular processes involved in cancer progression. HCC development is recognized as a multistep process that normally develops over many years. Over this period several mutations accumulate in the cell and that stimulate malign transformation, growth, and metastatic behavior. Over the recent years it has become evident that not only the tumor cell itself but also the tumor microenviroment plays a major role in the development of a tumor. There is a direct link between the role of inflammation and cirrhosis with this microenviroment. Both in vitro and in vivo it has been shown that tumor formation and metastatic properties are linked to epithelial-mesenchymal transition (EMT), a process by which facillitates the tumor cell's attempts to migrate to a more favourable microenviroment. Several groups have analyzed the gene expression in HCC and its surrounding tissue by microarray and this has resulted in the molecular classification into a distinct number of classes. Here we also found a role for hypoxia induced gene expression leading to a clinically more aggressive gene expression in HCC. Molecular analysis also helped to identify important cellular pathways and possible therapeutic targets. The first molecule that in this way has shown clinical application for liver cancer is the multikinase inhibitor sorafenib, others are currently in different stages of clinical studies like the mTOR inhibitor everolimus.

Mammalian Su(var) genes in chromatin control

Genetic screens in Drosophila have been instrumental in distinguishing approximately 390 loci involved in position effect variegation and heterochromatin stabilization. Most of the identified genes [so-called Su(var) and E(var) genes] are also conserved in mammals, where more than 50 of their gene products are known to localize to constitutive heterochromatin. From these proteins, approximately 12 core heterochromatin components can be inferred. In addition, there are approximately 30 additional Su(var) and 10 E(var) factors that can, under distinct developmental options, interchange with constitutive heterochromatin and participate in the partitioning of the genome into repressed and active chromatin domains. A significant fraction of the Su(var) and E(var) factors are enzymes that respond to environmental and metabolic signals, thereby allowing both the variation and propagation of epigenetic states to a dynamic chromatin template. Moreover, the misregulation of human SU(VAR) and E(VAR) function can advance cancer and many other human diseases including more complex disorders. As such, mammalian Su(var) and E(var) genes and their products provide a rich source of novel targets for diagnosis of and pharmaceutical intervention in many human diseases.

Deciphering calcineurin inhibitor nephrotoxicity: a pharmacological approach

The calcineurin inhibitors ciclosporin and tacrolimus are used to prevent acute rejection of solid organs after transplantation. Their use can lead to chronic renal damage characterized by progressive and irreversible deterioration of renal function associated with interstitial fibrosis, tubular atrophy, arteriolar hyalinosis and glomerulosclerosis. Many approaches to better understand the mechanisms of this toxicity are in use. The aim of these approaches is to find biomarkers of early kidney injury and potential therapeutic targets. Despite these efforts, the biological processes leading to calcineurin inhibitor nephrotoxicity remain poorly understood. Furthermore, the diagnosis of chronic renal damage remains inaccurate without definitive diagnostic tools, no effective prevention exists and a therapy to treat the damage has yet to be developed. In this article, theories of pharmacodynamics, pharmacokinetics, therapeutic drug monitoring and pharmacogenetics are synthesized in ways that may improve the understanding of mechanisms leading to calcineurin inhibitor toxicity. The importance of global approaches such as toxicogenomics is emphasized to characterize early cellular responses implicated in calcineurin inhibitor nephrotoxicity.

Junctional music that the nucleus hears: cell-cell contact signaling and the modulation of gene activity

Cell-cell junctions continue to capture the interest of cell and developmental biologists, with an emerging area being the molecular means by which junctional signals relate to gene activity in the nucleus. Although complexities often arise in determining the direct versus indirect nature of such signal transduction, it is clear that such pathways are essential for the function of tissues and that alterations may contribute to many pathological outcomes. This review assesses a variety of cell-cell junction-to-nuclear signaling pathways, and outlines interesting areas for further study.

Mechanisms of tubulointerstitial fibrosis

The pathologic paradigm for renal progression is advancing tubulointerstitial fibrosis. Whereas mechanisms underlying fibrogenesis have grown in scope and understanding in recent decades, effective human treatment to directly halt or even reverse fibrosis remains elusive. Here, we examine key features mediating the molecular and cellular basis of tubulointerstitial fibrosis and highlight new insights that may lead to novel therapies. How to prevent chronic kidney disease from progressing to renal failure awaits even deeper biochemical understanding.

Fibroblast expression of an IκB dominant-negative transgene attenuates renal fibrosis

It is not clear whether interstitial fibroblasts or tubular epithelial cells are primarily responsible for the profibrotic effects of NF-κB activation during renal fibrogenesis. Here, we crossed mice carrying a conditional IκB dominant-negative transgene (IκBdN) with mice transgenic for cell-specific FSP1.Cre (FSP1(+) fibroblasts) or γGT.Cre (proximal tubular epithelia) and challenged all progeny with unilateral ureteral obstruction. We determined NF-κB activation by nuclear localization of phosphorylated p65 ((p)p65) in renal tissues after 7 days. We observed inhibition of NF-κB activation in interstitial cells and tubular epithelia in obstructed kidneys of FSP1.Cre;IκBdN and γGT.Cre;IκBdN mice, respectively, compared with IκBdN controls (P < 0.05). Deposition of extracellular matrix, however, was significantly lower in the obstructed kidneys of FSP1.Cre;IκBdN mice but not in γGT.Cre;IκBdN mice (P < 0.05). In addition, levels of mRNA encoding the profibrotic PAI-1, fibronectin-EIIIA, and type I (α1) procollagen were significantly lower in obstructed kidneys of FSP1.Cre;IκBdN mice compared with γGT.Cre;IκBdN mice (P < 0.05). Taken together, these data support a profibrotic role for fibroblasts, but not proximal tubular epithelial cells, in modulating NF-κB activation during renal fibrogenesis.

Histone deacetylase inhibition suppresses the transforming growth factor beta1-induced epithelial-to-mesenchymal transition in hepatocytes

Transforming growth factor beta1 (TGFbeta1) plays a crucial role in the induction of the epithelial-to-mesenchymal transition (EMT) in hepatocytes, which contributes to the pathogenesis of liver fibrosis. The inhibition of the TGFbeta1 cascade suppresses EMT and the resultant fibrosis. In this study, we focus on EMT-induced fibrosis in hepatocytes and the epigenetic regulation of the type I collagen gene. Histone acetylation is an important, major epigenetic mechanism that modulates gene transcription. We evaluated the epigenetic regulation of type I collagen in alpha mouse liver 12 hepatocytes (an untransformed mouse cell line) that had undergone EMT after treatment with TGFbeta1. The histone deacetylase inhibitor trichostatin A (TSA) inhibited EMT; this was reflected by the preservation of epithelial markers and function (E-cadherin and albumin). Fibrosis, the ultimate outcome of EMT, was abolished by TSA; this was indicated by the inhibition of type I collagen deposition. TSA exerted its anti-EMT effects by deactivating the mothers against decapentaplegic homolog 3 (Smad3)/Smad4 transcription complex and by interfering with p300, a coactivator of the type I collagen promoter, and preventing its binding to Smad3. TSA also restored Friend leukemia virus integration 1, an inhibitor of the type I collagen gene. TGFbeta1-induced EMT and its inhibition by TSA were replicated in human primary hepatocytes.

CONCLUSION

Histone deacetylase inhibition abrogates TGFbeta1-induced EMT in hepatocytes and reverses EMT-induced fibrosis by epigenetic modulation of type I collagen.

Resolved: EMT produces fibroblasts in the kidney

Epithelial-mesenchymal transition (EMT) is a mechanism for generating primitive mesenchymal cells during gastrulation or mobile tumor cells during cancer metastasis. For 15 years, EMT has also been viewed as a principal source of fibroblasts in tissue fibrosis. Because several recent studies question its role in fibrogenesis, it seems like a good time for debate.