Tissue inhibitor of metalloproteinase-1 protects MCF-7 breast cancer cells from paclitaxel-induced apoptosis by decreasing the stability of cyclin B1

Accurate prediction and key protein sequence feature identification of cyclins

Cyclin proteins are a group of proteins that activate the cell cycle by forming complexes with cyclin-dependent kinases. Identifying cyclins correctly can provide key clues to understanding the function of cyclins. However, due to the low similarity between cyclin protein sequences, the advancement of a machine learning-based approach to identify cycles is urgently needed. In this study, cyclin protein sequence features were extracted using the profile-based auto-cross covariance method. Then the features were ranked and selected with maximum relevance-maximum distance (MRMD) 1.0 and MRMD2.0. Finally, the prediction model was assessed through 10-fold cross-validation. The computational experiments showed that the best protein sequence features generated by MRMD1.0 could correctly predict 98.2% of cyclins using the random forest (RF) classifier, whereas seven-dimensional key protein sequence features identified with MRMD2.0 could correctly predict 96.1% of cyclins, which was superior to previous studies on the same dataset both in terms of dimensionality and performance comparisons. Therefore, our work provided a valuable tool for identifying cyclins. The model data can be downloaded from https://github.com/YUshunL/cyclin.

Integrated Transcriptomic Analysis Revealed Hub Genes and Pathways Involved in Sorafenib Resistance in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), a high mortality malignancy, has become a worldwide public health concern. Acquired resistance to the multikinase inhibitor sorafenib challenges its clinical efficacy and the survival benefits it provides to patients with advanced HCC. This study aimed to identify critical genes and pathways associated with sorafenib resistance in HCC using integrated bioinformatics analysis. Differentially expressed genes (DEGs) were identified using four HCC gene expression profiles (including 34 sorafenib-resistant and 29 sorafenib-sensitive samples) based on the robust rank aggregation method and R software. Gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID) online tool. A protein–protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING), and small molecules reversing sorafenib resistance were searched for using the connectivity map (CMAP) database. Pearson correlation and survival analyses of hub genes were performed using cBioPortal and Gene Expression Profiling and Interactive Analysis (GEPIA). Finally, the expression levels of hub genes in sorafenib-resistant HCC cells were verified using quantitative polymerase chain reaction (q-PCR). A total of 165 integrated DEGs (66 upregulated and 99 downregulated in sorafenib resistant samples compared sorafenib sensitive ones) primarily enriched in negative regulation of endopeptidase activity, extracellular exosome, and protease binding were identified. Some pathways were commonly shared between the integrated DEGs. Seven promising therapeutic agents and 13 hub genes were identified. These findings provide a strategy and theoretical basis for overcoming sorafenib resistance in HCC patients.

Implications of microgravity-induced cell signaling alterations upon cancer cell growth, invasiveness, metastatic potential, and control by host immunity

The human endeavor to venture beyond the orbit of Earth is challenged by both continuous space radiation and microgravity-induced immune dysfunction. If cancers were to develop in astronauts, it is unclear how these abnormal cells would grow and progress in the microgravity environment. It is unknown if the astronaut's immune response would be able to control or eradicate cancer. A better molecular understanding of how the mechanical force of gravity affects the cell as well as the aggressiveness of cancers and the functionality of host immunity is needed. This review will summarize findings related to microgravity-mediated alterations in the cell cytoskeleton, cell-cell, and cell-extracellular matrix interactions including cadherins, immunoglobulin superfamily of adhesion molecules, selectins, and integrins and related cell signaling. The effects of spaceflight and simulated microgravity on cell viability, cancer cell growth, invasiveness, angiogenesis, metastasis as well as immune cell functions and the subsequent signaling pathways involved will be discussed. Microgravity-induced alterations in function and signaling of the major anti-cancer immune populations will be examined including natural killer cells, dendritic cells, CD4⁺ T cells, and CD8⁺ T cells. Further studies regarding the molecular events impacted by microgravity in both cancer and immune cells will greatly increase the development of therapies to restrict tumor growth and enhance cancer-specific responses for both astronauts and patients on Earth.

Identification of Cultivable Bacteria in Amniotic Fluid Using Cervicovaginal Fluid Protein Microarray in Preterm Premature Rupture of Membranes

We aimed to identify cervicovaginal fluid (CVF) protein biomarkers of microbial invasion of the amniotic cavity (MIAC) in women with preterm premature rupture of membranes (PPROM), using an antibody microarray. This retrospective cohort study included 99 consecutive women with singleton pregnancies and PPROM (23-33 weeks) who underwent amniocentesis and who gave CVF samples. CVF proteomes from the MIAC (n = 20) versus non-MIAC groups (n = 20) were comparatively profiled by an antibody microarray using a nested case-control study design. The seven candidate biomarkers of interest were validated in the total cohort (n = 99) by enzyme-linked immunosorbent assays (ELISA). For comparison with candidate markers, amniotic fluid (AF) white blood cell (WBC) count was also measured. The primary outcome measure was MIAC (defined as positive AF culture). Thirty of the proteins studied exhibited significant intergroup differences. Measurements of the total cohort with ELISA confirmed a significant increase in the levels of CVF IL-8, lipocalin-2, MIP-1α, MMP-9, and TIMP-1 in women with MIAC, independent of gestational age at sampling. A combined, non-invasive model was developed by using a stepwise regression procedure, which included CVF IL-8 and CVF MMP-9 (area under the curve [AUC] = 0.763), and this AUC was comparable with the AUC of AF WBC. Using protein-antibody microarray technology, we found several novel, independent, non-invasive biomarkers to identify MIAC in women with PPROM: IL-8, lipocalin-2, MIP-1α, MMP-9, and TIMP-1. Furthermore, the combined non-invasive model (IL-8 and MMP-9) was a useful independent predictor for MIAC with good discriminatory power, similar to AF WBC count.

Human tissue inhibitor of metalloproteinases-1 improved wound healing in diabetes through its anti-apoptotic effect

Impaired wound healing accompanies severe cell apoptosis in diabetic patients. Tissue inhibitor of metalloproteinases-1 (TIMP-1) was known to have effects on promoting growth and anti-apoptosis for cells. We aimed to determine the actual levels of TIMP-1 and cell apoptosis in: (i) the biopsies of diabetic and non-diabetic foot tissue and (ii) the human fibroblasts with or without treatments of advanced glycation end-products (AGEs). Next, we aimed to determine the improved levels of cell apoptosis and wound healing after the treatments of either active protein of TIMP-1 or in vivo expression of gene therapy vector-mediated TIMP-1 in both the human fibroblasts and the animal model of diabetic rats. The levels of TIMP-1 were significantly reduced in diabetic skin tissues and in AGEs-treated fibroblasts. Both AGEs-treated cells were effectively protected from apoptosis by active protein of TIMP-1 at appropriate dose level. So did the induced in vivo TIMP-1 expression after gene delivery. Similar effects were also found on the significant improvement of impaired wound healing in diabetic rats. We concluded that TIMP-1 improved wound healing through its anti-apoptotic effect. Treatments with either active protein TIMP-1 or TIMP-1 gene therapy delivered in local wound sites may be used as a strategy for accelerating diabetic wound healing.

TIMP-1 downregulation modulates miR-125a-5p expression and triggers the apoptotic pathway

Matrix metalloproteinases and their natural inhibitors (TIMPs) are important elements in a wide range of oncology settings. Elevated levels of tissue inhibitor of metalloproteinase-1 (TIMP-1) have often been associated with increased tumorigenesis. This has been demonstrated in a number of clinical and experimental models which include breast, gastric, colorectal and non-small cell lung carcinoma (NSCLC). Our earlier studies have identified increased angiogenic activity and aggressive tumor kinetics in TIMP-1 overexpressing H2009 lung adenocarcinoma cells. TIMP-1 overexpression has also been implicated in antiapoptotic responses, inducing a significant upregulation of Bcl-2. These TIMP-1 functions have been shown to be MMP-independent and provide insight into its pleiotropic activities. The current study examines microRNA (miRNA) interactions with this molecule. We have sought to define the relationship between TIMP-1 and miRNA by knocking down TIMP-1 in high TIMP-1 expressing lung adenocarcinoma cell lines. TIMP-1 knockdown resulted in increased expression of miR-125a-5p with a concomitant increase in apoptosis and attenuation of the tumorigenic features of these cells. We have identified TIMP-1 as a bona fide target of miR-125a-5p, and their interaction resulted in an increase in p53 expression. We further corroborated our in vitro data with patient samples, which exhibited an inverse correlation between TIMP-1 and miR-125a-5p expression. Our study lends support to the notion that elevated TIMP-1 levels, which are frequently associated with poor prognosis, cause aberrant modulation of miRNAs.

Overexpression of TIMP-1 and Sensitivity to Topoisomerase Inhibitors in Glioblastoma Cell Lines

The multifunctional protein - tissue inhibitor of metalloproteinases-1 (TIMP-1) - has been associated with a poor prognosis in several types of cancers including glioblastomas. In addition, TIMP-1 has been associated with decreased response to chemotherapy, and especially the efficacy of the family of topoisomerase (TOP) inhibitors has been related to TIMP-1. As a second line treatment of glioblastomas, the vascular endothelial growth factor (VEGF) antibody bevacizumab is administered in combination with the TOP1 inhibitor irinotecan and glioblastoma cell levels of TIMP-1 could therefore potentially influence the efficacy of such treatment. In the present study, we aimed to investigate whether a high TIMP-1 expression in glioblastoma cell lines would affect the sensitivity to TOP inhibitors, and whether TIMP-1 overexpressing cells would have alterered growth and invasion. We established TIMP-1 overexpressing subclones from two human glioblastoma cell lines. TIMP-1 overexpressing U87MG cells were significantly more resistant than low TIMP-1 expressing clones and parental cells when exposed to SN-38 (TOP1 inhibitor) or epirubicin (TOP2 inhibitor). No significant differences were observed for the TIMP-1 transfected A172 cells. Implantation of both U87MG and A172 spheroids into organotypic brain slice cultures revealed a reduced growth of TIMP-1 overexpressing U87MG spheroids, however, no significant differences in invasion were observed. The present study suggests that TIMP-1 overexpression reduces the effect of TOP inhibitors in glioblastoma. TIMP-1 also appeared to reduce spheroid growth, but did not influence invasion. Whether TIMP-1 plays a role in irinotecan resistance and has a predictive potential in glioblastoma patients remains to be elucidated.

The Cdc2/Cdk1 inhibitor, purvalanol A, enhances the cytotoxic effects of taxol through Op18/stathmin in non-small cell lung cancer cells in vitro

Purvalanol A is a highly selective inhibitor of Cdc2 [also known as cyclin-dependent kinase 1 (CDK1)]. Taxol is an anti-tumor chemotherapeutic drug which is widely used clinically. In this study, the CDK1 inhibitor, purvalanol A was applied to explore the relevance of Cdc2 signaling and taxol sensitivity through analyses, such as cellular proliferation and apoptosis assays, ELISA, western blot analysis and immunoprecipitation. We demonstrated that purvalanol A effectively enhanced the taxol-induced apoptosis of NCI-H1299 cells, as well as its inhibitory effects on cellular proliferation and colony formation. In combination, purvalanol A and taxol mainly decreased the expression of oncoprotein 18 (Op18)/stathmin and phosphorylation at Ser16 and Ser38, while purvalanol A alone inhibited the phosphorylation of Op18/stathmin at all 4 serine sites. Co-treatment with purvalanol A and taxol weakened the expression of Bcl-2 and activated the extrinsic cell death pathway through the activation of caspase-3 and caspase-8. Further experiments indicated that Cdc2 kinase activities, including the expression of Cdc2 and the level of phospho-Cdc2 (Thr161) were significantly higher in taxol-resistant NCI-H1299 cells compared with the relatively sensitive CNE1 cells before and following treatment with taxol. These findings suggest that Cdc2 is positively associatd with the development of taxol resistance. The Cdc2 inhibitor, purvalanol A, enhanced the cytotoxic effects of taxol through Op18/stathmin. Our findings may prove to be useful in clinical practice, as they may provide a treatment strategy with which to to reduce the doses of taxol applied clinically, thus alleviating the side-effects.

BPIQ, a novel synthetic quinoline derivative, inhibits growth and induces mitochondrial apoptosis of lung cancer cells in vitro and in zebrafish xenograft model

Background

2,9-Bis[2-(pyrrolidin-1-yl)ethoxy]-6-{4-[2-(pyrrolidin-1-yl)ethoxy] phenyl}-11H-indeno[1,2-c]quinolin-11-one (BPIQ) is a derivative from 6-arylindeno[1,2-c]quinoline. Our previous study showed the anti-cancer potential of BPIQ compared to its two analogues topotecan and irinotecan. In the study, the aim is to investigate the potency and the mechanism of BPIQ against lung cancer cells.

Methods

Both in vitro and zebrafish xenograft model were performed to examine the anti-lung cancer effect of BPIQ. Flow cytometer-based assays were performed for detecting apoptosis and cell cycle distribution. Western blot assay was used for detecting the changes of apoptotic and cell cycle-associated proteins. siRNA knockdown assay was performed for confirming the apoptotic role of Bim.

Results

Both in vitro and zebrafish xenograft model demonstrated the anti-lung cancer effect of BPIQ. BPIQ-induced proliferative inhibition of H1299 cells was achieved through the induction of G₂/M-phase arrest and apoptosis. The results of Western blot showed that BPIQ-induced G₂/M-phase arrest was associated with a marked decrease in the protein levels of cyclin B and cyclin-dependent kinase 1 (CDK1). The up-regulation of pro-apoptotic Bad, Bim and down-regulation of pro-survival XIAP and survivin was observed following BPIQ treatment.

Conclusions

BPIQ-induced anti-lung cancer is involved in mitochondrial apoptosis. BPIQ could be a promising anti-lung cancer drug for further applications.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1970-x) contains supplementary material, which is available to authorized users.

The telomere/telomerase binding factor PinX1 regulates paclitaxel sensitivity depending on spindle assembly checkpoint in human cervical squamous cell carcinomas

Paclitaxel is a main ingredient in the combination chemotherapy treatment of advanced human cervical squamous cell carcinomas. We investigated the roles and underlying molecular mechanisms of PinX1 in cervical squamous cell carcinomas (CSCC) cells response to paclitaxel and its clinical significances. The expression dynamics of PinX1 was first examined by immunohistochemistry in 122 advanced CSCC patients treated with cisplatin/paclitaxel chemotherapy. The expression of PinX1 was significantly associated with the effects of cisplatin/paclitaxel chemotherapy in advanced CSCCs (P<0.05). High expression of PinX1 correlated with CSCC's response to cisplatin/paclitaxel chemotherapy, and was an independent predictor of shortened survival (P<0.05). A series of in vivo and in vitro assays were performed to elucidate the function of PinX1 on CSCC cells chemosensitivity to paclitaxel and underlying mechanisms. In CSCC cells, the levels of PinX1 were only associated with the cytotoxicity and sensitivity of paclitaxel, in which knockdown of PinX1 dramatically enhanced paclitaxel cytotoxicity, whereas the reestablishment of PinX1 levels substantially reduced the paclitaxel-induced killing effect. In addition, we identified that the ability of PinX1 to stabilize the tension between sister kinetochores and maintain the spindle assembly checkpoint was the main reason CSCC cells undergo apoptosis when treated with paclitaxel, and further studies demonstrated that shortened distance between sisters kinetochores by nocodazole confers upon PinX1-replenished cells a sensitivity to the death inducing paclitaxel effects. Furthermore, our study of CSCC cells xenografts in nude mice confirmed the role of PinX1 in paclitaxel sensitivity in vivo. Our data reveal that PinX1 could be used as a novel predictor for CSCC patient response to paclitaxel, and the role of PinX1-mediated paclitaxel sensitivity might represent a new direction for the development of a new generation of microtubule drugs.

Cytokine functions of TIMP-1

The tissue inhibitors of metalloproteinases (TIMPs) are well recognized for their role in extracellular matrix remodeling by controlling the activity of matrix metalloproteinases (MMPs). Independent of MMP inhibition, TIMPs act as signaling molecules with cytokine-like activities thereby influencing various biological processes including cell growth, apoptosis, differentiation, angiogenesis, and oncogenesis. Recent studies on TIMP-1's cytokine functions have identified complex regulatory networks involving a specific surface receptor and subsequent signaling pathways including miRNA-mediated posttranscriptional regulation of gene expression that ultimately control the fate and behavior of the cells. The present review summarizes the current knowledge on TIMP-1 as a cytokine modulator of cell functions, outlines recent progress in defining molecular pathways that transmit TIMP-1 signals from the cell periphery into the nucleus, and discusses TIMP-1's role as a cytokine in the pathophysiology of cancer and other human diseases.

TIMP-1 increases expression and phosphorylation of proteins associated with drug resistance in breast cancer cells

Tissue inhibitor of metalloproteinase 1 (TIMP-1) is a protein with a potential biological role in drug resistance. To elucidate the unknown molecular mechanisms underlying the association between high TIMP-1 levels and increased chemotherapy resistance, we employed SILAC-based quantitative mass spectrometry to analyze global proteome and phosphoproteome differences of MCF-7 breast cancer cells expressing high or low levels of TIMP-1. In TIMP-1 high expressing cells, 312 proteins and 452 phosphorylation sites were up-regulated. Among these were the cancer drug targets topoisomerase 1, 2A, and 2B, which may explain the resistance phenotype to topoisomerase inhibitors that was observed in cells with high TIMP-1 levels. Pathway analysis showed an enrichment of proteins from functional categories such as apoptosis, cell cycle, DNA repair, transcription factors, drug targets and proteins associated with drug resistance or sensitivity, and drug transportation. The NetworKIN algorithm predicted the protein kinases CK2a, CDK1, PLK1, and ATM as likely candidates involved in the hyperphosphorylation of the topoisomerases. Up-regulation of protein and/or phosphorylation levels of topoisomerases in TIMP-1 high expressing cells may be part of the mechanisms by which TIMP-1 confers resistance to treatment with the widely used topoisomerase inhibitors in breast and colorectal cancer.

Overexpression of cyclin B1 antagonizes chemotherapeutic-induced apoptosis through PTEN/Akt pathway in human esophageal squamous cell carcinoma cells

The role of cyclin B1 in the clinical therapeutic sensitivity of human esophageal squamous cell carcinoma (ESCC) remains to be defined. In this study, we found that elevated cyclin B1 expression attenuated the apoptosis induced by cisplatin or paclitaxel, while knockdown of cyclin B1 enhanced cisplatin or paclitaxel sensitivity in ESCC cells. Cyclin B1-mediated apoptosis may rely on the Bcl-2-dependent mitochondria-regulated intrinsic death pathway, and the antagonizing effect of cyclin B1 on chemotherapeutic agent-induced apoptosis was through PTEN/Akt pathway. Therefore, cyclin B1 might be a therapeutic target for the development of specific and efficient approaches in the treatment of ESCC.

Microcystin-LR promotes melanoma cell invasion and enhances matrix metalloproteinase-2/-9 expression mediated by NF-κB activation

This study aimed to explore the molecular mechanisms behind the stimulation effects of microcystin-LR (a well-known cyanobacterial toxin produced in eutrophic lakes or reservoirs) on cancer cell invasion and matrix metalloproteinases (MMPs) expression. Boyden chamber assay showed that microcystin-LR exposure (>12.5 nM) evidently enhanced the invasion ability of the melanoma cells (MDA-MB-435). Tumor Metastasis PCR Array demonstrated that 24 h microcystin-LR treatment (25 nM) caused overexpression of eight genes involved in tumor metastasis, including MMP-2, MMP-9, and MMP-13. Quantitative real-time PCR, Western blotting and gelatin zymography consistently demonstrated that mRNA and protein levels of MMP-2/-9 were increased in the cells after microcystin-LR exposure (P < 0.05 each). Immunofluorescence assay and electrophoretic mobility shift assay revealed that microcystin-LR could activate nuclear factor kappaB (NF-κB) by accelerating NF-κB translocation into the nucleus and enhancing NF-κB binding ability. Furthermore, addition of NF-κB inhibitor in culture medium could suppress the invasiveness enhancement and MMP-2/-9 overexpression. This study indicates that microcystin-LR can act as a NF-κB activator to promote MMP-2/-9 expression and melanoma cell invasion, which deserves more environmental health concerns.

Predictive biomarkers with potential of converting conventional chemotherapy to targeted therapy in patients with metastatic colorectal cancer

The availability of systemic chemotherapy regimens for the treatment of patients with metastatic colorectal cancer (mCRC) is based on the results from large prospective, randomized studies. The main chemotherapeutic drugs used in treatment of mCRC are the fluoropyrimidines (5-fluorouracil (5-FU); capecitabine) in combination with either oxaliplatin (FOLFOX) or irinotecan (FOLFIRI). The objective response rate to either combination is approximately 50%, where no significant differences with regard to progression free survival or overall survival have been observed. Interestingly, a number of preclinical and clinical studies have indicated lack of full cross resistance between oxaliplatin based and irinotecan based treatment. Therefore, it is possible that certain mCRC patient subpopulations would benefit more from one drug combination rather than the other. To address this clinical problem there has been much focus on development and validation of predictive biomarkers for these three drugs. Here, we present a thorough review on the current status of predictive biomarkers for 5-FU, oxaliplatin and irinotecan treatment of mCRC patients. The overall conclusions were as follows: Several promising biomarker candidates were identified, notably thymidylate synthase for 5-FU, topoisomerase I for irinotecan and ERCC1 for oxaliplatin. However, these candidates warrant further analysis, where assay performance and clinical trial design should be in focus.

Low MAD2 expression levels associate with reduced progression-free survival in patients with high-grade serous epithelial ovarian cancer

Epithelial ovarian cancer (EOC) has an innate susceptibility to become chemoresistant. Up to 30% of patients do not respond to conventional chemotherapy [paclitaxel (Taxol®) in combination with carboplatin] and, of those who have an initial response, many patients relapse. Therefore, an understanding of the molecular mechanisms that regulate cellular chemotherapeutic responses in EOC cells has the potential to impact significantly on patient outcome. The mitotic arrest deficiency protein 2 (MAD2), is a centrally important mediator of the cellular response to paclitaxel. MAD2 immunohistochemical analysis was performed on 82 high-grade serous EOC samples. A multivariate Cox regression analysis of nuclear MAD2 IHC intensity adjusting for stage, tumour grade and optimum surgical debulking revealed that low MAD2 IHC staining intensity was significantly associated with reduced progression-free survival (PFS) (p = 0.0003), with a hazard ratio of 4.689. The in vitro analyses of five ovarian cancer cell lines demonstrated that cells with low MAD2 expression were less sensitive to paclitaxel. Furthermore, paclitaxel-induced activation of the spindle assembly checkpoint (SAC) and apoptotic cell death was abrogated in cells transfected with MAD2 siRNA. In silico analysis identified a miR-433 binding domain in the MAD2 3′ UTR, which was verified in a series of experiments. Firstly, MAD2 protein expression levels were down-regulated in pre-miR-433 transfected A2780 cells. Secondly, pre-miR-433 suppressed the activity of a reporter construct containing the 3′-UTR of MAD2. Thirdly, blocking miR-433 binding to the MAD2 3′ UTR protected MAD2 from miR-433 induced protein down-regulation. Importantly, reduced MAD2 protein expression in pre-miR-433-transfected A2780 cells rendered these cells less sensitive to paclitaxel. In conclusion, loss of MAD2 protein expression results in increased resistance to paclitaxel in EOC cells. Measuring MAD2 IHC staining intensity may predict paclitaxel responses in women presenting with high-grade serous EOC. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Hypoxia decreased chemosensitivity of breast cancer cell line MCF-7 to paclitaxel through cyclin B1

Hypoxia, frequently found in the center of solid tumors, may lead to enhance the production of key factor in cell survival, invasion, angiogenesis and loss of apoptosis. The low oxygen tension in hypoxic tumors is also known to interfere with the efficacy of chemotherapy, but the underlying mechanisms are not very clear. Paclitaxel (PTX) is an active agent used in breast cancer chemotherapy, which disturbs microtubule dynamics and impairs the transition of cells from metaphase to anaphase in mitosis, leading to cell death by apoptosis. In the present study, we try to determine whether hypoxia can decrease the chemosensitivity of human breast carcinoma cells to PTX and elucidate the underlying mechanism. We found that hypoxia could decrease PTX-induced cell death and G(2)/M arrest. Furthermore, our results showed that hypoxia inhibit PTX-induced soluble tubulin polymerized. In addition, we also found hypoxia could suppress PTX-induced cell cycle protein-cyclin B1 expression in MCF-7 cells. To further investigate whether the inhibitory effect of hypoxia on PTX-induced cell death is mediated by decreasing levels of cyclin B1, cyclin B1-transfected MCF-7 cells were used under hypoxic condition. The data showed that the hypoxia-based decreasing chemosensitivity of breast cancer cells to PTX was reversed by cyclin B1. We also found that overexpression of cyclin B1 could significantly increase the sensitivity of MCF-7 cells to PTX by stimulating soluble polymerized tubulin. Overall, hypoxia decreases cyclin B1, which could in turn reverse hypoxia-induced decreasing chemosensitivity to PTX in breast cancer cell line MCF-7.

An alternate perspective on the roles of TIMPs and MMPs in pathology

Tissue inhibitors of metalloproteinases (TIMPs) are pleiotropic extracellular proteins. TIMPs are recognized as endogenous regulators of matrix metalloproteinases (MMPs), a large family of extracellular enzymes with proteolytic activities that participate in cellular homeostasis, adaptation, and tissue remodeling. In addition to their roles as endogenous potent MMP inhibitors, accumulating evidence indicates important physiological roles for TIMPs that are independent of their ability to block MMP activities. For instance, MMP-independent actions of TIMP-1 in the central nervous system have been implicated in synaptic plasticity, neuroprotection, oncogenesis, and oligodendrocyte differentiation. Expression of TIMP-1 is dramatically increased in response to a variety of injurious and inflammatory insults. In the context of disease pathogenesis, MMP and TIMP expression are interpreted with respect to the proteolytic consequences of increased MMP/TIMP ratios. Here, we provide an alternative perspective on the homeostatic balance of TIMP and MMP proteins, whereby consideration is given to the possible role of MMPs as cognate inhibitors of the signaling functions of TIMPs. Thus, MMPs may regulate the receptor-mediated actions of TIMPs, inasmuch as TIMPs are themselves inhibitors of MMP-mediated proteolytic activities. This broader view reflects our emerging understanding that TIMP signaling and MMP inhibition represent two important functions of TIMPs that have the potential to affect tissue pathology.

Invading basement membrane matrix is sufficient for MDA-MB-231 breast cancer cells to develop a stable in vivo metastatic phenotype

INTRODUCTION

The poor efficacy of various anti-cancer treatments against metastatic cells has focused attention on the role of tumor microenvironment in cancer progression. To understand the contribution of the extracellular matrix (ECM) environment to this phenomenon, we isolated ECM surrogate invading cell populations from MDA-MB-231 breast cancer cells and studied their genotype and malignant phenotype.

METHODS

We isolated invasive subpopulations (INV) from non invasive populations (REF) using a 2D-Matrigel assay, a surrogate of basal membrane passage. INV and REF populations were investigated by microarray assay and for their capacities to adhere, invade and transmigrate in vitro, and to form metastases in nude mice.

RESULTS

REF and INV subpopulations were stable in culture and present different transcriptome profiles. INV cells were characterized by reduced expression of cell adhesion and cell-cell junction genes (44% of down regulated genes) and by a gain in expression of anti-apoptotic and pro-angiogenic gene sets. In line with this observation, in vitro INV cells showed reduced adhesion and increased motility through endothelial monolayers and fibronectin. When injected into the circulation, INV cells induced metastases formation, and reduced injected mice survival by up to 80% as compared to REF cells. In nude mice, INV xenografts grew rapidly inducing vessel formation and displaying resistance to apoptosis.

CONCLUSION

Our findings reveal that the in vitro ECM microenvironment per se was sufficient to select for tumor cells with a stable metastatic phenotype in vivo characterized by loss of adhesion molecules expression and induction of pro-angiogenic and survival factors.

Prospective evaluation of serum tissue inhibitor of metalloproteinase 1 and carbonic anhydrase IX in correlation to circulating tumor cells in patients with metastatic breast cancer

INTRODUCTION

Circulating tumor cells (CTCs) reflect aggressive tumor behavior by hematogenous tumor cell dissemination. The tissue inhibitor of metalloproteinase 1 (TIMP-1) plays a role in tissue invasion and is also involved in angiogenesis, abrogation of apoptosis and in chemoresistance. Carbonic anhydrase IX (CAIX) is a metalloenzyme involved in cell adhesion, growth and survival of tumor cells. The aim of the study was to investigate whether serum concentrations of TIMP-1 and CAIX are associated with the detection of CTC in metastatic breast cancer.

METHODS

Blood was obtained in a prospective multicenter setting from 253 patients with metastatic breast cancer at the time of disease progression. Serum TIMP-1 and CAIX were determined using commercial ELISA-kits (Oncogene Science). CTC were detected with the CellSearch system (Veridex).

RESULTS

Five or more CTCs were detected in 122 patients out of 245 evaluable patients (49.8%). Out of 253 metastatic patients 70 (28%) had serum TIMP-1 levels above 454 ng/mL. Serum CAIX was elevated above 506 ng/mL in 90 (35%) patients. Both serum markers had prognostic significance. Median progression free survival (PFS) was 7.2 months with elevated TIMP-1 vs. 11.4 months with non-elevated levels (p < 0.01). OS was 11.5 vs. 19.1 months (p < 0.01). Median PFS was 7.5 months with elevated CAIX vs. 11.7 months with non-elevated levels (p < 0.01), overall survival (OS) was 13.4 months vs. 19.1 months (p < 0.01). In patients with five or more CTCs, serum levels were above the cut-off for CAIX in 47% vs. 25% in those with less than five CTCs (p = 0.01). For TIMP-1, 37% patients with five or more CTCs had elevated serum levels and 17% of patients with less than five CTCs (p = 0.01). Including TIMP-1, CAIX, CTC and established prognostic factors in the multivariate analysis, the presence of CTCs, the therapy line and elevated CAIX remained independent predictors of OS.

CONCLUSIONS

Elevated serum levels of the invasion markers TIMP-1 and CAIX in metastatic breast cancer are prognostic markers and are associated with the presence of CTCs. Whether increased secretion of TIMP-1 and/or CAIX might directly contribute to tumor cell dissemination remains to be elucidated in further investigations.

TRIAL REGISTRATION

Current Controlled Trials: ISRCTN59722891.

TIMP-1 deficiency subverts cell-cycle dynamics in murine long-term HSCs

In addition to the well-recognized role in extracellular matrix remodeling, the tissue inhibitor of metalloproteinases-1 (TIMP-1) has been suggested to be involved in the regulation of numerous biologic functions, including cell proliferation and survival. We therefore hypothesized that TIMP-1 might be involved in the homeostatic regulation of HSCs, whose biologic behavior is the synthesis of both microenvironmental and intrinsic cues. We found that TIMP-1(-/-) mice have decreased BM cellularity and, consistent with this finding, TIMP-1(-/-) HSCs display reduced capability of long-term repopulation. Interestingly, the cell cycle distribution of TIMP-1(-/-) stem cells appears distorted, with a dysregulation at the level of the G(1) phase. TIMP-1(-/-) HSCs also display increased levels of p57, p21, and p53, suggesting that TIMP-1 could be intrinsically involved in the regulation of HSC cycling dynamics. Of note, TIMP-1(-/-) HSCs present decreased levels of CD44 glycoprotein, whose expression has been proven to be controlled by p53, the master regulator of the G(1)/S transition. Our findings establish a role for TIMP-1 in regulating HSC function, suggesting a novel mechanism presiding over stem cell quiescence in the framework of the BM milieu.