Showing papers on "Cancer research published in 2014"

Propranolol inhibits angiogenesis via down-regulating the expression of vascular endothelial growth factor in hemangioma derived stem cell

Abstract: Background: Oral propranolol (PRN) has recently been shown to be highly effective for infantile hemangiomas (IHs), and is currently recommended as the first-line treatment of complicated IHs. However, the therapeutic mechanism(s) still remain unclear. Methods: In this study, we tested hemangioma-derived stem cells for expression of vascular endothelial growth factor (VEGF) in vitro and studied the inhibition of VEGF expression. We used PCR, Elisa, Western blotting and immunohistochemistry in vivo and in vitro trial. Results: The study demonstrated that application of PRN at a “normal” concentration equivalent to plasma concentration did not inhibit proliferation or promote apoptosis of hemangioma derived stem cells (HemSCs) isolated from IH patients. PRN suppressed expression of vascular endothelial growth factor (VEGF) and basic Fibroblast Growth Factor (bFGF) in HemSCs in vitro. Morphological, histological and immunohistological improvement were observed in vivo using murine IH model in which HemSCs pre-treated with PRN were implanted into BALB/c-nu mice. In the pre-treated HemSC grafts, mean micro-vessel density (MVD) significantly decreased and protein levels of VEGF markedly decreased, while bFGF was still detectable. Conclusions: The results suggested PRN inhibited angiogenesis via down-regulating the expression of vascular endothelial growth factor in hemangioma derived stem cell. These findings provide critical insight into the potential mechanisms of PRN action on IH.

JG6, a novel marine-derived oligosaccharide, suppresses breast cancer metastasis via binding to cofilin

Abstract: Cofilin, an actin-binding protein which disassembles actin filaments, plays an important role in invasion and metastasis. Here, we discover that JG6, an oligomannurarate sulfate, binds to cofilin, suppresses the migration of human breast cancer cells and cancer metastasis in breast cancer xenograft model. Mechanistically, JG6 occupies actin-binding sites of cofilin, thereby disrupting cofilin modulated actin turnover. Our results highlight the significance of cofilin in cancer and suggest JG6, a cofilin inhibitor, to treat metastatic cancer.

Extracellular vesicles as mediators of intercellular communication in human breast cancer progression

Abstract: The establishment of a permissive tumor microenvironment is a key step for tumor progression and metastasis formation. Tumor cells are known for their ability to create such a favorable tumor niche by influencing the surrounding benign stroma cells through the secretion of cytokines or growth factors. Recently, there is increasing evidence that also extracellular vesicles (EV) released by the tumor cells are important means of intercellular communication. Therefore, we aimed to investigate their role in tumor-tumor and tumor-stroma crosstalk in human breast cancer. Human breast cancer cells were found to release tumor microvesicles (T-MV) as well as tumor exosomes (T-Exo). Both significantly enhanced invasiveness of the tumor cells in an auto- and heterologous feedback loop, whereas benign MV or the particle-free supernatant had no such effect. In case of T-MV, their pro-invasive function was dependent on a dynamin-dependent uptake into their recipient cells. Moreover, all pro-invasive T-MV carried a highly-glycosylated isoform of the Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) with N-glycosylation at N160 and N268. Anti-EMMPRIN strategies such as knockdown or deglycosylation antagonized the pro-invasive function of T-MV on tumor invasion. Interestingly, EMMPRIN-carrying T-MV increased tumor invasiveness in a matrix metalloproteinase-independent mechanism by activating p38/MAPK signaling. EMMPRIN is not only involved in MV-mediated pro-invasive tumor-tumor crosstalk in vitro, but can also be used as a novel marker to detect T-MV which are circulating at high numbers in peripheral blood of breast cancer patients in vivo. Apart from their autologous influence on tumor invasion, we identified tumor-EV (T-EV) as mediators of a reciprocal tumor-macrophage communication loop. They were able to reprogram macrophages by inducing Wnt5a expression which was not observed for benign MV. Wnt5a induction was mediated by p38/MAPK signaling which could be antagonized by the Wnt-inhibitor DKK-1. Macrophage-Wnt5a was then exported on macrophage-derived EV and transported back to the tumor cells where it increased their invasive potential. Wnt5a expression on EV was shown to depend on the seven-pass transmembrane protein Evenness interrupted (Evi) which had been demonstrated so far only for exosomes and not for non-canonical Wnt ligands like Wnt5a. In conclusion, breast cancer cells were demonstrated to release T-EV into the local environment as well as the bloodstream, where they interact with surrounding tumor as well as stroma cells and support the establishment of a favorable tumor niche.

Attenuated apoptosis as consequence of Epithelial Mesenchymal Transition

Abstract: The developmental program of Epithelial Mesenchymal Transition (EMT) is assumed to be involved in tumor progression, enabling cancer cells to spread from the primary tumor and form metastasis in distant tissues. At least in some cases, disseminated tumor cells display tumor-initiating properties similar to stem cells. In addition, these cells tend to resist chemo-therapy. However, it is unclear how cells gain the competency to escape chemotherapeutic treatment upon EMT. In order to investigate the role of EMT in chemotherapeutic resistance and the underlying mechanisms, we used a HMLE RAS (Human Mammary Large T-Antigen immortalized Epi-thelial HaRas expressing cell) model system. This EMT system is composed of two different cell lines. On the one hand, the so called 24+ RAS cells display an epithelial morphology and lack efficient migration. On the other hand, the MSP RAS cells (mesenchymal subpopulation) that originate from the 24+ RAS cells have undergone EMT, accompanied by a mesenchymal cell shape and high invasivity. In this study, we applied several chemotherapeutic treatments to both cell lines to assess their response to chemotherapy. We found that, in contrast to 24+ RAS cells, MSP RAS cells are resistant to the chemothera-peutics Cisplatin, Doxorubicin and Neocarzinostain, but also to the death ligands Trail and TNFα, as seen by reduced PARP and Caspase 3 cleavage upon treatment. Beyond that, we showed that the anti-apoptotic Bcl-2 family member Bcl-xL is overexpressed in MSP RAS cells, in comparison to 24+ RAS, which enables former cells to survive chemotherapy and to continue proliferation after treatment. We have demonstrated that retrovirus-mediated Bcl-xL overexpression in 24+HMLE renders these cells chemoresistant, as well. Conversely, knocking down Bcl-xL in MSP RAS cells rendered them sensitive to death stimuli. Strikingly, we found Bcl-xL overexpressed in human breast cancer cells at the tumor-stroma-interface, suggesting a general role of Bcl-xL in mi-grating cancer cells. We found that inhibition of Bcl-xL with the BH3 mimic Gossypol results in chemosensitivity of MSP RAS cells. The same observation was obtained upon Bcl-xL de-stabilization, mediated by the inhibition of the chaperone HSP90 in vitro and in vivo, demon-strating that we found an option to overcome chemoresistance of cells that have undergone EMT. In conclusion, our data reveal Bcl-xL as a key mediator of apoptosis-resistance in cells upon EMT. We propose a causal relation between EMT, Bcl-xL overexpression and chemo-resistance, and we suggest Bcl-xL as a promising target in cancer therapies.

Молекулярно-биологические характеристики злокачественных новообразований

Abstract: The review presents the main and additional features that distinguish tumor cells from normal tissue cells. They include sustained proliferative signaling, evasion from growth suppressors, resisting cell death, enabling replicative immortality, angiogenesis induction, and invasion and metastasis activation. Basis for the formation of these features is provided by tumor genome instability. Tumors are complex tissues that consist of different cell types interacting with each other as well as with normal cells. An important characteristic of tumor cells is the ability to interact with the tumor microenvironment and the formation of tumor stroma.

Insulin-like growth factor 2 promotes ovarian cancer growth and resistance to traditional chemotherapy.

Abstract: Tesis (Doctor en Ciencias Biologicas, mencion en Ciencias Fisiologicas)--Pontificia Universidad Catolica de Chile, 2014.

Drug Metabolism Determines Resistance of Colorectal Cancer to Resorcinol-Based HSP90 Inhibitors

Abstract: Tumor cells are characterized by intrinsic proteotoxic stress and the accumulation of mutated proteins. Therefore, malignant cells depend on the activity of heat shock protein 90 (HSP90) much more than normal cells to maintain a functionally intact proteome. Thus, the inhibition of HSP90 by small molecules is currently being evaluated as a new approach to cancer therapy. One of the most promising drugs of this class is ganetespib, which is currently in intensive clinical trials. We analyzed the susceptibility of colorectal cancer (CRC) cell lines to ganetespib and recorded large differences in the cell line-specific drug concentrations required for 50% growth inhibition (IC50). Two groups of cancer cells became apparent; ganetespib-sensitive and -resistant cell lines with a difference in IC50 values up to 70–fold (36 – 2,500 nM). Therefore, the aim of this study was to elucidate the molecular determinants that govern the response of CRC cells to ganetespib treatment. A statistical correlation of the IC50 values of CRC cell lines with their transcriptomes revealed that the expression of UDP-glucuronosyltransferase 1A (UGT1A) correlates strongly with resistance to ganetespib. UGT1A is involved in the metabolism of a variety of drugs, and it has been previously reported that high expression levels of this enzyme in cancer cells are responsible for the resistance to some established chemotherapeutic drugs. Knockdown of UGT1A in ganetespib-resistant cells and overexpression of UGT1A in ganetespib-sensitive cells confirmed the causal connection of increased ganetespib tolerance to the expression of UGT1A. The protective effect of UGT1A was also observed by immunoblot analysis of HSP90 clients, as they were not degraded in sensitive cell lines despite the presence of ganetespib when UGT1A was overexpressed. A similar resistance in cells with increased UGT1A expression was also observed for another, structurally related HSP90 inhibitor, NVP-AUY922. However, HSP90 inhibitors from other classes do not seem to be subject to glucuronidation-induced resistance mechanisms. We hypothesize that glucuronidation by UGT1A takes place at the resorcinol moiety of ganetespib and NVP-AUY922. The metabolites of this glucuronidation process, the glucuronides of ganetespib and NVP-AUY922, were detected by mass spectrometry in a collaborating laboratory to support this hypothesis. In summary, we show that the biological activities of ganetespib and NVP-AUY922, two resorcinolic HSP90 inhibitors, are impaired by UGT1A-catalyzed glucuronidation in CRC cell lines. Notably, the UGT1A expression levels of primary CRC tumor samples have been found to be in the same range as in the CRC cell lines. Therefore, the occurrence of resistance to ganetespib and NVP-AUY922 in clinical applications is a conceivable scenario. We suggest that the expression of UGT1A can be used as a drug-related biomarker in cancer to ensure the activity of resorcinolic HSP90 inhibitors. These findings are of pivotal importance for the clinical application of these drugs in cancers which have the potential to express UGT1A.

Cooperation of p300 and iASPP in apoptosis and tumour suppression

Abstract: Mutation or functional inactivation of tumour suppressors represents a key event in the transformation of cells and contributes to the development of cancer. P300 and CBP constitute two histone acetyltransferases with tumour suppressor functions that are frequently mutated or functional inactivated in cancer. Accordingly, after chemotherapy-induced DNA damage, for example, p300 and CBP can co-activate the key tumour suppressor proteins p53 and TAp73, thereby contributing to tumour cell apoptosis. Here we investigated the impact of the co-factor protein iASPP on p300 and TAp73 function, after treatment of tumourigenic cell lines with the chemotherapeutic drug cisplatin. iASPP belongs to the ASPP-family, another class of co-factors that contribute to p53-family-mediated apoptosis induction. Direct interaction of iASPP with p300 and TAp73 has been revealed before; functional consequences of these interactions remain elusive though and are therefore subject of our analyses. By investigating the consequences of stable iASPP knockdown in tumourigenic cell lines, we found that direct interaction of iASPP and p300 in cisplatin-treated cells led to enhanced protein stability of p300 and TAp73. Correspondingly, iASPP depletion resulted in decreased protein amounts of p300, reduced induction of pro-apoptotic p73 target genes and impaired apoptosis. BRMS1 represents a recently discovered E3 ubiquitin ligase for p300. Hence, we observed that BRMS1 depletion rescued the degradation of p300 and CBP in cisplatin-treated, iASPP-depleted cells. Therefore, we hypothesize that BRMS1 inhibition constitutes the molecular mechanism underlying the increased protein stability of p300 in the presence of iASPP. Furthermore, we discovered, that malignant melanoma are characterized by down-regulated iASPP expression level. Follow-up studies on melanoma cell lines revealed that low iASPP expression correlated with decreased protein levels of p300 in cisplatin-treated cells. BRMS1 knockdown in some of these cell lines could up-regulate p300 protein level, suggesting that down-regulation of iASPP expression leads to functional inactivation of p300 in melanoma, by allowing BRMS1 activity on p300. Treatment of the cells with the MKP-1 inhibitor BCI, could re-establish p300 level and induce p300-dependent apoptosis by yet unknown mechanisms. Summing up, iASPP represents a regulator for p300 function. It contributes to p300-dependent apoptosis induction by enhancing its protein stability after DNA damage. Re-establishment of p300 levels in low iASPP-expressing melanoma might represent a novel strategy to overcome chemoresistance.