Differential modulation of the cytokine-induced MMP-9/TIMP-1 protease-antiprotease system by the mTOR inhibitor rapamycin

Tocotrienol isoforms: The molecular mechanisms underlying their effects in cancer therapy and their implementation in clinical trials

Tocotrienols are found in a variety of natural sources, like rice bran, annatto seeds and palm oil, and have been shown to have several health-promoting properties, particularly against chronic diseases such as cancer. The incidence of cancer is rapidly increasing around the world, not only a result of continued aging and population growth, but also due to the adoption of aspects of the Western lifestyle, such as high-fat diets and low-physical activity. The literature provides strong evidence that tocotrienols are able to inhibit the growth of various cancers, including breast, lung, ovarian, prostate, liver, brain, colon, myeloma and pancreatic cancers. These findings, along with the reported safety profile of tocotrienols in healthy human volunteers, encourage further research into these compounds' potential use in cancer prevention and treatment. The current review provided detailed information about the molecular mechanisms of action of different tocotrienol isoforms in various cancer models and evaluated the potential therapeutic effects of different vitamin E analogues on important cancer hallmarks, such as cellular proliferation, apoptosis, angiogenesis and metastasis. MEDLINE/PubMed and Scopus databases were used to identify recently published articles that investigated the anticancer effects of vitamin E derivatives in various types of cancer in vitro and in vivo along with clinical evidence of adjuvant chemopreventive benefits. Following an overview of pre-clinical studies, we describe several completed and ongoing clinical trials that are paving the way for the successful implementation of tocotrienols in cancer chemotherapy.

hUMSCs Restore Uterine Function by Inhibiting Endometrial Fibrosis via Regulation of the MMP-9/TIMP-1 Ratio in CDDP-Induced Injury Rats

The fertility of females of childbearing age who are cured of cancer by chemotherapy is gradually declining globally. As a broad-spectrum chemotherapy drug in clinic, the damage of cisplatin (CDDP) to female reproductive function cannot be ignored. At present, the study of CDDP damage to the uterus is not sufficient, and the exact mechanism needs to be further explored. Therefore, we conducted this research to determine whether uterine injury in CDDP-induced injury rats might be improved by human umbilical cord mesenchymal stem cells (hUMSCs) and to further explore the precise mechanism. The rat model of CDDP-induced injury was established by intraperitoneal injection of CDDP, and hUMSCs were injected into the tail vein 7 days later. In vivo, uterine function in CDDP-induced injury rats was affected after hUMSC transplantation. In vitro, the specific mechanism was further explored from the cell and protein levels. Overall, the specific reason of CDDP-induced uterine dysfunction in rats was endometrial fibrosis, which was significantly improved after hUMSC transplantation. Further investigation of the mechanism found that hUMSCs could regulate the ratio of matrix metalloproteinase-9 (MMP-9)/tissue inhibitor of metalloproteinase-1 (TIMP-1) in endometrial stromal cells (EnSCs) after CDDP injury.

Short-term rapamycin treatment increases life span and attenuates aortic aneurysm in a murine model of Marfan-Syndrome

BACKGROUND

Marfan syndrome (MFS) is a genetic disorder leading to medial aortic degeneration and life-limiting dissections. To date, there is no causal prevention or therapy. Rapamycin is a potent and selective inhibitor of the mechanistic target of rapamycin (mTOR) protein kinase, regulating cell growth and metabolism. The mgR/mgR mice represent an accepted MFS model for studying aortic pathologies to understand the underlying molecular pathomechanisms. This study investigated whether rapamycin inhibits the development of thoracic aortic aneurysms and dissections in mgR/mgR mice.

METHODS

Isolated primary aortic smooth muscle cells (mAoSMCs) from mgR/mgR mice were used for in vitro studies. Two mg kg/BW rapamycin was injected intraperitoneally daily for two weeks, beginning at 7-8 weeks of age. Mice were sacrificed 30 days post-treatment. Histopathological and immunofluorescence analyses were performed using adequate tissue specimens and techniques. Animal survival was evaluated accompanied by periodic echocardiographic examinations of the aorta.

RESULTS

The protein level of the phosphorylated ribosomal protein S6 (p-RPS6), a downstream target of mTOR, was significantly increased in the aortic tissue of mgR/mgR mice. In mAoSMCs isolated from these animals, expression of mTOR, p-RPS6, tumour necrosis factor α, matrix metalloproteinase-2 and -9 was significantly suppressed by rapamycin, demonstrating its anti-inflammatory capacity. Short-term rapamycin treatment of Marfan mice was associated with delayed aneurysm formation, medial aortic elastolysis and improved survival.

CONCLUSIONS

Short-term rapamycin-mediated mTOR inhibition significantly reduces aortic aneurysm formation and thus increases survival in mgR/mgR mice. Our results may offer the first causal treatment option to prevent aortic complications in MFS patients.

The Effect of Chronic Immunosuppressive Regimens Treatment on Aortal Media Morphology and the Balance between Matrix Metalloproteinases (mmp-2 and mmp-9) and Their Inhibitors in the Abdominal Aorta of Rats

Immunosuppressive drugs are widely and chronically used to avoid graft rejection in transplant recipients. However, they are also known to have organotoxic effects and can exert numerous side effects. The aim of this study was to assess whether the chronic treatment of rats with the most commonly used clinical immunosuppressive regimens in organ recipients had an effect on the morphology and function of the aorta. The rats were divided into five groups and each group was chronically treated with different sets of three immunosuppressive drugs (TRG, CRG, MRG, CMG, TMG) for 6 months. The changes were most profound in calcineurin inhibitor-based protocols. TMG protocol treatment was characterized by the most numerous alterations such as morphological changes, changes in the thickness of the tunic media, wider distances between elastic lamellae, an increase in the number of vSMCs and changes in collagen deposition. We concluded that the morphological changes were connected with MMP-2 and MMP-9/TIMP-2 and TIMP-1 imbalances, which was also determined and noticed.

Everolimus Inhibits the Progression of Ductal Carcinoma In Situ to Invasive Breast Cancer Via Downregulation of MMP9 Expression

PURPOSE

We evaluated the role of everolimus in the prevention of ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) progression.

EXPERIMENTAL DESIGN

The effects of everolimus on breast cancer cell invasion, DCIS formation, and DCIS progression to IDC were investigated in a 3D cell culturing model, intraductal DCIS xenograft model, and spontaneous MMTV-Her2/neu mouse model. The effect of everolimus on matrix metalloproteinase 9 (MMP9) expression was determined with Western blotting and IHC in these models and in patients with DCIS before and after a window trial with rapamycin. Whether MMP9 mediates the inhibition of DCIS progression to IDC by everolimus was investigated with knockdown or overexpression of MMP9 in breast cancer cells.

RESULTS

Everolimus significantly inhibited the invasion of human breast cancer cells in vitro. Daily intragastric treatment with everolimus for 7 days significantly reduced the number of invasive lesions from intraductal DCIS foci and inhibited DCIS progression to IDC in the MMTV-Her2/neu mouse mammary tumor model. Mechanistically, everolimus treatment decreased the expression of MMP9 in the in vitro and in vivo models, and in breast tissues from patients with DCIS treated with rapamycin for 1 week. Moreover, overexpression of MMP9 stimulated the invasion, whereas knockdown of MMP9 inhibited the invasion of breast cancer cell-formed spheroids in vitro and DCIS in vivo. Knockdown of MMP9 also nullified the invasion inhibition by everolimus in vitro and in vivo.

CONCLUSIONS

Targeting mTORC1 can inhibit DCIS progression to IDC via MMP9 and may be a potential strategy for DCIS or early-stage IDC therapy.

Delta-tocotrienol inhibits non-small-cell lung cancer cell invasion via the inhibition of NF-κB, uPA activator, and MMP-9

Background

Delta-tocotrienol (δT), an isomer of vitamin E, exhibits anticancer properties in different cancer types including non-small-cell lung cancer (NSCLC). Yet, anti-invasive effects of δT and its underlying cellular mechanism in NSCLC have not been fully explored. Matrix metalloproteinase 9 (MMP-9)-based cell migration and invasion are critical cellular mechanisms in cancer development. The current evidence indicates that MMP-9 is upregulated in most patients, and the inhibition of MMPs is involved in decreasing invasion and metastasis in NSCLC. Therefore, its suppression is a promising strategy for attenuating cell invasion and metastasis processes in NSCLC.

Purpose

The aim of this study was to evaluate the possibility of MMP-9 inhibition as the underlying mechanism behind the antimetastatic properties of δT on NSCLC cells.

Methods

The effects of δT on cell proliferation, migration, invasion, adhesion, and aggregation capabilities were investigated using different cell-based assays. An inhibitory effect of MMP-9 enzyme activity with δT was also identified using gel zymography. Using real-time PCR and Western blot analysis, a number of cellular proteins, regulatory genes, and miRNA involved in the Notch-1 and urokinase-type plasminogen activator (uPA)-mediated MMP-9 pathways were examined.

Results

The study found that δT inhibited cell proliferation, cell migration, invasion, aggregation, and adhesion in a concentration-dependent manner and reduced MMP-9 activities. Real-time PCR and Western blot analysis data revealed that δT increased miR-451 expressions and downregulated Notch-1-mediated nuclear factor-κB (NF-κB), which led to the repressed expression of MMP-9 and uPA proteins.

Conclusion

δT attenuated tumor invasion and metastasis by the repression of MMP-9/uPA via downregulation of Notch-1 and NF-κB pathways and upregulation of miR-451. The data suggest that δT may have potential therapeutic benefit against NSCLC metastasis.

Epithelial-mesenchymal transition in Crohn's disease

Crohn's disease (CD) is often accompanied by the complications of intestinal strictures and fistulas. These complications remain obstacles in CD treatment. In recent years, the importance of epithelial-mesenchymal transition in the pathogenesis of CD-associated fistulas and intestinal fibrosis has become apparent. Epithelial-mesenchymal transition refers to a dynamic change, wherein epithelial cells lose their polarity and adherence and acquire migratory function and fibroblast features. During formation of CD-associated fistulas, intestinal epithelial cells dislocate from the basement membrane and migrate to the lining of the fistula tracts, where they convert into transitional cells as a compensatory response under the insufficient wound healing condition. In CD-associated intestinal fibrosis, epithelial-mesenchymal transition may serve as a source of new fibroblasts and consequently lead to overproduction of extracellular matrix. In this review, we present current knowledge of epithelial-mesenchymal transition and its role in the pathogenesis of CD in order to highlight new therapy targets for the associated complications.

Loss of the Protein Cystathionine β-Synthase During Kidney Injury Promotes Renal Tubulointerstitial Fibrosis

BACKGROUND/AIMS

Renal tubulointerstitial fibrosis (TIF) is the common pathway of progressive chronic kidney disease. Inflammation has been widely accepted as the major driving force of TIF. Cystathionine β-synthase (CBS) is the first and rate-limiting enzyme in the transsulfuration pathway. CBS is considered to play protective role in liver and pulmonary fibrosis, but its role in TIF remains unknown. The purpose of this study was to investigate the potential role and mechanism of CBS in renal inflammation and TIF.

METHODS

Renal function, tubulointerstitium damage index score, extracellular matrix (ECM) deposition, and the expressions of collagen I, collagen III, fibronectin, CD3, CD68, IL-1β, TNF-α were measured in sham operation and unilateral ureteral obstruction (UUO) rats. Proteomics and gene array analysis were performed to screen differentially expressed molecules in the development of renal inflammation and TIF in UUO rats. The expression of CBS was detected in patients with obstructive nephropathy and UUO rats. We confirmed the expression of CBS using western blot and real-time PCR in HK-2 cells. Overexpression plasmid and siRNA were transfected specifically to study the possible function of CBS in HK-2 cells.

RESULTS

Abundant expression of CBS, localized in renal tubular epithelial cells, was revealed in human and rat renal tissue, which correlated negatively with the progression of fibrotic disease. Expression of CBS was dramatically decreased in the obstructed kidney from UUO rats as compared with the sham group (SHM). In addition, knocking down CBS exacerbated extracellular matrix (ECM) deposition, whereas CBS overexpression attenuated TGF-β1-induced ECM deposition in vitro. Inflammatory and chemotactic factors were also increased in CBS knockdown HK-2 cells stimulated by IL-1β.

CONCLUSIONS

These findings establish CBS as a novel inhibitor in renal fibrosis and as a new therapeutic target in patients with chronic kidney disease.

Matrine inhibits the metastatic properties of human cervical cancer cells via downregulating the p38 signaling pathway

Matrine is a traditional Chinese herbal medicine that shows antitumor efficacy for many types of cancer. The present study evaluated the antitumor efficacy of matrine on cervical cancer and to investigate the underlying mechanisms. We performed MTT assays, and in vitro invasion and migration assays, and P1 L6 found that matrine significantly inhibited cervical cancer cell growth by inducing apoptosis, and suppressed the invasion and migration ability of cervical cancer cells in vitro in a concentration-dependent manner. Mechanistically, we found that matrine decreased the expression and activity of the extracellular matrix factors, matrix metalloproteinases-2 (MMP-2) and MMP-9 via the suppression of p38 signaling pathway. In addition, when cervical cancer cells were grown as xenografts in nude mice, intraperitoneal (i.p.) injection of matrine induced a significant dose-dependent decrease in tumor growth. Taken together, these findings suggest that a potential mechanism by which matrine inhibits the growth and metastasis of cervical cancer through downregulating the p38 signaling pathway.

Expression of pro-fibrotic and anti-fibrotic molecules in dimethylnitrosamine-induced hepatic fibrosis

BACKGROUND

Hepatic fibrosis is characterized by a progressive accumulation of fibrillar extracellular matrix (ECM) proteins, produced by activated myofibroblasts which are modulated by both profibrotic and antifibrotic factors.

OBJECTIVE

To evaluate in vivo the expression of pro-fibrotic molecules like avβ6 integrin, transforming growth factor-β (TGF-β), Smad3, connective tissue growth factor (CTGF) and mammalian target of Rapamycin (mTOR), as well as anti-fibrotic peroxisome proliferator-activated receptor-γ (PPARγ) in an experimental model of chronic hepatitis-associated fibrosis induced by intraperitoneal administration of dimethylnitrosamine (DMN) in mice.

METHODS

Chronic hepatitis was induced in 12 Smad3 wild-type (WT) and 12 knock-out (KO) mice by intraperitoneal DMN administration. Histological, morphometric and immunohistochemical analyses using α-smooth muscle actin (α-SMA), collagen types I-III, TGF-β1, Smad3, avβ6 integrin, CTGF, mTOR and PPARγ antibodies were performed.

RESULTS

The liver of DMN-treated Smad3 WT mice showed a higher degree of hepatic accumulation of connective tissue compared to KO mice. The expression of α-SMA, collagen I-III and CTGF was increased in Smad3 WT compared to KO mice treated with DMN, associated with a concomitant up-regulation of avβ6, TGFβ, Smad3, and mTOR and a reduction in PPARγ expression.

CONCLUSIONS

These results suggest a possible interaction between pro-fibrotic and anti-fibrotic molecules in the development of hepatic fibrosis.

MMP2 and MMP7 at the invasive front of gastric cancer are not associated with mTOR expression

Background

Regulation of MMP expression by activation of mTOR signalling has been demonstrated for several tumor types, but has thus far not been confirmed in gastric cancer.

Findings

The study compromised 128 patients who underwent gastric resection for cancer (66.4 % male; 86 intestinal, 42 diffuse type). Immunohistochemical staining of MMPs was performed to analyse the topographical pattern of MMP expression at the tumor center and the invasive front, respectively. MMP2 showed higher expression at the invasive front compared to the tumor center, whereas MMP7 staining scores were higher in the tumor center, and there was no difference for MMP9. The expression of p-mTOR was higher in the tumor center than at the invasive front, with a similar trend for mTOR. For intestinal type gastric cancer there was a weak correlation of MMP9 with expression of mTOR in the tumor center. Otherwise, there was no correlation of the MMPs with mTOR. By treatment of MKN45 gastric cancer cells with rapamycin, a reduction of p-mTOR in the Western blot was achieved; however, expression of MMPs remained unaffected.

Conclusions

Expression of MMP2 and MMP7 in gastric cancer is not associated with mTOR, MMP9 expression might be related to mTOR signalling in a subset of tumors.

Electronic supplementary material

The online version of this article (doi:10.1186/s13000-015-0449-z) contains supplementary material, which is available to authorized users.

Medical Therapy of Fibrostenotic Crohn's Disease

Introduction

The present review serves to provide a concise overview of the current knowledge on therapeutic strategies with regard to fibrostenotic lesions in Crohn's disease.

Methods

A literature search was performed focusing on the last 5 years, and current concepts of pathophysiology, epidemiology, and treatment have been summarized.

Results

Fibrostenotic lesions in Crohn's disease are currently considered to be a consequence of the chronic inflammatory nature of the disease. Hence, therapeutic strategies are limited to the concept that early treatment of the inflammatory lesions can prevent structural changes, and to various endoscopic and surgical approaches. Direct targeting of the fibrostenotic lesion itself has not been the focus until now. This review will provide an overview of the pathophysiology and epidemiology of fibrostenotic lesions including current therapeutic approaches. Since research with regard to other organ systems and fibrosis is far more advanced, current strategies from available studies in these areas will be discussed. The results and the potential impact for Crohn's disease will be considered.

Conclusion

The vision of these approaches is to reverse structural changes and restore normal function.

Tubulin-binding agents down-regulate matrix metalloproteinase-2 and -9 in human hormone-refractory prostate cancer cells – a critical role of Cdk1 in mitotic entry

Tubulin is an important target for anticancer therapy. Taxanes and vinca alkaloids are two groups of tubulin-binding agents in cancer chemotherapy. Besides tubulin binding, these groups of agents can also down-regulate protein levels of matrix metalloproteinase (MMP)-2 and -9, two important cancer-associated zinc-dependent endopeptidases in invasion and metastasis. However, the mechanism of action waits to be explored. In this study, protein levels but not mRNA expressions of MMP-2 and -9 were down-regulated by paclitaxel (a microtubule-stabilization agent), vincristine and evodiamine (two tubulin-depolymerization agents). These agents induced an increase of protein expression of cyclin B1, MPM2 (mitosis-specific phosphoprotein) and polo-like kinase (PLK) 1 phosphorylation. The data showed a negative relationship between the levels of mitotic proteins and MMP-2 and -9 expressions. MG132 (a specific cell-permeable proteasome inhibitor) blocked mitotic entry and arrested cell cycle at G2 phase, preventing down-regulation of MMP-2 and -9. Cell cycle synchronization experiments by thymidine block or nocodazole treatment showed that mitotic exit inhibited the down-regulation of MMP-2 and -9, confirming negative relationship between cell mitosis and protein levels of MMP-2 and -9 expressions. Cyclin-dependent kinase (Cdk) 1 is a key kinase in mitotic entry. Knockdown of Cdk1 almost completely inhibited the down-regulation of MMP-2 and -9 induced by tubulin-binding agents. In conclusion, the data suggest that mitotic entry and Cdk1 plays a central role in down-regulation of MMP-2 and -9 protein expressions. Tubulin-binding agents cause mitotic arrest and Cdk1 activation, which may contribute largely to the down-regulation of both MMP-2 and -9 expressions.

Vertical inhibition of PI3K/Akt/mTOR signaling demonstrates in vitro and in vivo anti-fibrotic activity

BACKGROUND

The mammalian target of rapamycin (mTOR) regulates cellular activity in many diseases, but the complex interplay with PI3K/Akt pathway may hampers its function.

OBJECTIVE

This study was undertaken to determine the activity of PI3K/Akt/mTOR signaling in the fibroblasts from systemic sclerosis (SSc) patients, and compare the effects of vertical inhibiting PI3K/Akt/mTOR by BEZ235 and inhibiting mTOR alone by rapamycin in fibroblast activation and in two complementary established mouse model of SSc.

METHODS

Pharmaceutical specific inhibitors BEZ235 and rapamycin were used to vertical inhibit PI3K/Akt/mTOR signaling and mTOR signaling alone in cultured fibroblasts and in mice. SSc mouse model was established by daily injecting bleomycin subcutaneously or by overexpression of constitutively active type I TGF-β receptor (TβRI(ca)). To delineate the mechanisms underlying the antifibrotic effects of BEZ235 and rapamycin, activity of PI3K/Akt/mTOR signaling was analyzed by determining the expressions of phosphorylated Akt, GSK-3β, mTOR and S6 ribosomal protein (S6).

RESULTS

Primary dermal fibroblasts demonstrated hyperactivity of PI3K/Akt and mTOR signaling. mTOR inhibitor rapamycin failed to inhibit dermal fibrosis in an established SSc mouse model. However, administration of a dual inhibitor for PI3K/Akt and mTOR signaling BEZ235 attenuated dermal fibrosis by reversing increased dermal thickness and collagen deposition in two SSc mouse models. Furthermore, BEZ235 showed superior inhibitory effect on fibroblast activation relative to rapamycin in vitro. Also both BEZ235 and rapamycin could prevent the phosphorylation of mTOR and S6 completely. BEZ235 also blocked the activation of Akt and GSK-3β dramatically, whereas rapamycin has been shown to increase further upregulation of phosphorylated Akt on Ser473 both in vitro and in vivo.

CONCLUSION

These data show that blocking PI3K/Akt/mTOR with BEZ235 leads to superior inhibitory effect for dermal fibrosis, suggesting that vertical inhibition of PI3K/Akt/mTOR signaling may have therapeutic potential for SSc.

Medical therapy of stricturing Crohn's disease: what the gut can learn from other organs - a systematic review

Crohn’s disease (CD) is a chronic remitting and relapsing disease. Fibrostenosing complications such as intestinal strictures, stenosis and ultimately obstruction are some of its most common long-term complications. Despite recent advances in the pathophysiological understanding of CD and a significant improvement of anti-inflammatory therapeutics, medical therapy for stricturing CD is still inadequate. No specific anti-fibrotic therapy exists and the incidence rate of strictures has essentially remained unchanged. Therefore, the current therapy of established fibrotic strictures comprises mainly endoscopic dilation as well as surgical approaches. However, these treatment options are associated with major complications as well as high recurrence rates. Thus, a specific anti-fibrotic therapy for CD is urgently needed. Importantly, there is now a growing body of evidence for prevention as well as effective medical treatment of fibrotic diseases of other organs such as the skin, lung, kidney and liver. In face of the similarity of molecular mechanisms of fibrogenesis across these organs, translation of therapeutic approaches from other fibrotic diseases to the intestine appears to be a promising treatment strategy. In particular transforming growth factor beta (TGF-β) neutralization, selective tyrosine kinase inhibitors, blockade of components of the renin-angiotensin system, IL-13 inhibitors and mammalian target of rapamycin (mTOR) inhibitors have emerged as potential drug candidates for anti-fibrotic therapy and may retard progression or even reverse established intestinal fibrosis. However, major challenges have to be overcome in the translation of novel anti-fibrotics into intestinal fibrosis therapy, such as the development of appropriate biomarkers that predict the development and accurately monitor therapeutic responses. Future clinical studies are a prerequisite to evaluate the optimal timing for anti-fibrotic treatment approaches, to elucidate the best routes of application, and to evaluate the potential of drug candidates to reach the ultimate goal: the prevention or reversal of established fibrosis and strictures in CD patients.

Localization of ανβ6 integrin-TGF-β1/Smad3, mTOR and PPARγ in experimental colorectal fibrosis

A simultaneous action of several pro-fibrotic mediators appears relevant in the development of fibrosis. There are evidences that transforming growth factor-β (TGF-β)/Smad3 pathway forms with αvβ6 integrin, mammalian target of Rapamycin (mTOR) and peroxisome proliferator-activated receptor-γ (PPARγ) a complex signalling network with extensive crosstalk and strong effects on fibrosis development. The present study evaluated the expression of TGFβ, Smad3, αvβ6 integrin, mTOR and PPARγ in 2, 4, 6-trinitrobenzenesulphonic acid (TNBS)-induced colorectal fibrosis in Smad3 wild-type (WT) and null mice. Smad3 WT mice treated with TNBS developed a marked colorectal fibrosis and showed a concomitant up-regulation of TGFβ, Smad3, αvβ6 and mTOR and a reduction of PPARγ expression. On the other hand, Smad3 Null mice similarly treated with TNBS did not develop fibrosis and showed a very low or even absent expression of TGFβ, Smad3, αvβ6 and mTOR and a marked over-expression of PPARγ. At the same time the expression of α-smooth muscle actin (a marker of activated myofibroblasts), collagen I-III and connective tissue growth factor (a downstream effector of TGFβ/Smad3-induced extracellular matrix proteins) were up-regulated in Smad3 WT mice treated with TNBS compared to Null TNBS-treated mice. These preliminary results suggest a possible interaction between these pro-fibrotic molecules in the development of intestinal fibrosis.

Regulation of matrix metalloproteinase-1, -3, and -9 in Mycobacterium tuberculosis-dependent respiratory networks by the rapamycin-sensitive PI3K/p70(S6K) cascade

This study was designed to investigate the role of the phosphatidyl inositol 3-kinase (PI3K)/AKT/p70(S6K) signaling path on regulation of primary normal human bronchial epithelial cell-derived matrix metalloproteinase (MMP)-1, -3, and -9 expression in tuberculosis (TB). These MMPs are key in pathological extracellular matrix degradation in TB. Normal human bronchial epithelials were stimulated with conditioned medium from monocytes infected with virulent TB (CoMTb) and components of the PI3K/AKT signaling pathway blocked using specific chemical inhibitors and siRNA. MMP gene expression was measured by RT-PCR and secretion by ELISA, luminex, or zymography. Phospho-p70 S6K was detected by Western blot analysis and activity blocked by rapamycin. Chemical blockade of the proximal catalytic PI3K p110 subunit augmented MMP-1 and MMP-9 in a dose-dependent manner (all P<0.001) but suppressed MMP-3 (P<0.01). Targeted siRNA studies identified the p110α isoform as key causing 5-fold increase in TB network-dependent MMP-1 secretion to 4900 ± 1100 pg/ml. Specific inhibition of the AKT node suppressed all 3 MMPs. Phospho-p70(S6K) was identified in the cellular model, and rapamycin, a p70(S6K) inhibitor, inhibited MMP-1 (P<0.001) and MMP-3 (P<0.01) but not MMP-9. Controls were epithelial cells that were unstimulated or exposed to conditioned medium from monocytes not exposed to TB. In summary, blockade of the proximal PI3K catalytic subunit increases MMP-1 and MMP-9, whereas rapamycin decreased both MMP-1 and MMP-3. The regulation of the PI3K path in TB is complex, MMP specific, and a potential immunotherapeutic target in diseases characterized by tissue destruction.

Rhein inhibits integrin-linked kinase expression and regulates matrix metalloproteinase-9/tissue inhibitor of metalloproteinase-1 ratio in high glucose-induced epithelial-mesenchymal transition of renal tubular cell

Studies have found overexpressed integrin-linked kinase (ILK) and disturbed matrix metalloproteinase-9/tissue inhibitor of metalloproteinase-1 (MMP-9/TIMP-1) ratio in diabetic nephropathy epithelial-mesenchymal transition (EMT). However, the underlying mechanisms of EMT and the inhibiting effect of rhein need further understanding. The aim of this study was to investigate the possible regulating effects of ILK towards MMP-9/TIMP-1 ratio in EMT and the inhibiting effect of rhein. The characteristic epithelial marker and mesenchymal marker of EMT were examined by cytoimmunostaining, real-time reverse transcription polymerase chain reaction (real-time RT-PCR) and Western blot. To observe the EMT inhibiting effects of rhein, specific ILK-small interfering RNA (ILK-siRNA) was used as a positive control. The results showed that in high glucose conditions, overexpression of ILK and an abnormal changing of MMP-9/TIMP-1 ratio occurred; ILK inhibition by siRNA could adjust MMP-9/TIMP-1 ratio to near normal. Meanwhile, rhein inhibited the overexpressing ILK and inhibits high glucose-induced EMT; the effect was similar to that of ILK-siRNA. The decreased expression of ILK regulated by rhein contributed to the adjustment of the MMP-9/TIMP-1 ratio. Our data indicates that rhein inhibits high glucose-induced-EMT partially through the inhibition of ILK expression and regulates the MMP-9/TIMP-1 ratio in HK-2 cells. This mechanism may be associated with rhein's effect of ILK suppression.

Cellular and molecular mechanisms of intestinal fibrosis

Fibrosis is a chronic and progressive process characterized by an excessive accumulation of extracellular matrix (ECM) leading to stiffening and/or scarring of the involved tissue. Intestinal fibrosis may develop in several different enteropathies, including inflammatory bowel disease. It develops through complex cell, extracellular matrix, cytokine and growth factor interactions. Distinct cell types are involved in intestinal fibrosis, such as resident mesenchymal cells (fibroblasts, myofibroblasts and smooth muscle cells) but also ECM-producing cells derived from epithelial and endothelial cells (through a process termed epithelial- and endothelial-mesenchymal transition), stellate cells, pericytes, local or bone marrow-derived stem cells. The most important soluble factors that regulate the activation of these cells include cytokines, chemokines, growth factors, components of the renin-angiotensin system, angiogenic factors, peroxisome proliferator-activated receptors, mammalian target of rapamycin, and products of oxidative stress. It soon becomes clear that although inflammation is responsible for triggering the onset of the fibrotic process, it only plays a minor role in the progression of this condition, as fibrosis may advance in a self-perpetuating fashion. Definition of the cellular and molecular mechanisms involved in intestinal fibrosis may provide the key to developing new therapeutic approaches.

Mechanical injury suppresses autophagy regulators and pharmacologic activation of autophagy results in chondroprotection

OBJECTIVE

Mechanical injury induces cell death in cartilage and triggers a remodeling process that ultimately can manifest as osteoarthritis. Autophagy is a process for turnover of intracellular organelles and macromolecules that protects cells during stress responses. This study was undertaken to determine changes in and functions of autophagy following mechanical injury to cartilage.

METHODS

Bovine and human cartilage explants were subjected to mechanical impact (40% strain for 500 msec). Cell viability, sulfated glycosaminoglycan (sGAG) release, and changes in the levels of the autophagy markers ULK1, beclin 1, and microtubule-associated protein 1 light chain 3 (LC3) were evaluated. Cartilage explants were treated with the mammalian target of rapamycin complex 1 (mTORC-1) inhibitor and the autophagy inducer rapamycin and tested for protective effects against mechanical injury. Explants were also treated with the cell death inducers nitric oxide and tumor necrosis factor α (TNFα) plus actinomycin D, and the proinflammatory cytokine interleukin-1α (IL-1α).

RESULTS

Mechanical injury induced cell death and loss of sGAG in a time-dependent manner. This was associated with significantly decreased ULK1, beclin 1, and LC3 expression in the cartilage superficial zone (P < 0.05) 48 hours after injury. The levels of LC3-II were increased 24 hours after injury but decreased at 48 and 96 hours. Rapamycin enhanced expression of autophagy regulators and prevented cell death and sGAG loss in mechanically injured explants. Rapamycin also protected against cell death induced by sodium nitroprusside and TNFα plus actinomycin D and prevented sGAG loss induced by IL-1α.

CONCLUSION

Our findings indicate that mechanical injury leads to suppression of autophagy, predominantly in the superficial zone where most of the cell death occurs. Pharmacologic inhibition of mTORC-1, at least in part by enhancement of autophagy, prevents cell and matrix damage, suggesting a novel approach for chondroprotection.