Glucosinolates (GLs), natural compounds extracted from
Brassicaceae and precursors of isothiocyanates (ITCs), have been studied in the last decades mostly due to their chemopreventive activity and, ...more recently, for their potential use as novel chemotherapeutics. The aim of the present study was to investigate the
in vitro and
in vivo activity of glucomoringin (GMG), an uncommon member of the GLs family, and to compare it with glucoraphanin (GRA), one of the most studied GL. We have evaluated the potency of both compounds in inducing cell death, cell cycle perturbations, apoptosis, NF-kB inhibition and GST-π activity in human carcinoma cells with different GST-π contents as well as in human multiple myeloma and leukaemia cell lines. GMG-derived ITC (GMG-ITC) showed to be more effective compared to GRA-derived ITC (Sulforaphane), especially in inhibiting NF-kB activity and inducing apoptosis through a caspase-dependent pathway; these effects were more pronounced in myeloma cells, in which we could also observe a long lasting growth inhibitory effect, probably due to NF-kB inhibition, which is considered essential for myeloma cell survival. Both GLs were able to induce cell death in the μM range in all tested cell lines but caused cell cycle perturbations only in myeloma cells; they were also able to modulate the GST/GSH pathway by causing a 3-fold increase in GST-π activity in MCF7 cells.
In vivo study showed that pure GMG-ITC was only slightly active in a carcinoma mice model, whereas it had significant antitumoral activity in a myeloma model, causing little toxicity.
Therapy-induced senescence is a major cellular response to chemotherapy in solid tumors. Senescent tumor cells acquire a secretory phenotype, or SASP, and produce pro-inflammatory factors, whose ...expression is largely under NF-κB transcriptional control. Secreted factors play a positive role in driving antitumor immunity, but also exert negative influences on the microenvironment, and promote tumor growth and metastasis. Moreover, subsets of cancer cells can escape the senescence arrest, driving tumor recurrence after treatments. Hence, removal the senescent tumor cells, or reprogramming of the senescent secretome, have become attractive therapeutic options. The marine drug trabectedin was shown to inhibit the production of pro-inflammatory mediators by tumor-infiltrating immune cells and by myxoid liposarcoma cells. Here, we demonstrate that trabectedin inhibits the SASP, thus limiting the pro-tumoral activities of senescent tumor cells
. We show that trabectedin modulates NF-κB transcriptional activity in senescent tumor cells. This results in disruption of the balance between antiapoptotic and proapoptotic signals, and sensitization of cells to Fas-mediated apoptosis. Further, we found that trabectedin inhibits escape from therapy-induced senescence, at concentrations that do not affect the viability of bulk tumor population. Overall, our data demonstrate that trabectedin has the potential to inhibit multiple detrimental effects of therapy-induced senescence.
Trabectedin is a marine natural product, approved in Europe for the treatment of soft tissue sarcoma and relapsed ovarian cancer. Clinical and experimental evidence indicates that trabectedin is ...particularly effective against myxoid liposarcomas where response is associated to regression of capillary networks. Here, we investigated the mechanism of the antiangiogenic activity of trabectedin in myxoid liposarcomas. Trabectedin directly targeted endothelial cells, impairing functions relying on extracellular matrix remodeling (invasion and branching morphogenesis) through the upregulation of the inhibitors of matrix metalloproteinases TIMP‐1 and TIMP‐2. Increased TIMPs synthesis by the tumor microenvironment following trabectedin treatment was confirmed in xenograft models of myxoid liposarcoma. In addition, trabectedin upregulated tumor cell expression of the endogenous inhibitor thrombospondin‐1 (TSP‐1, a key regulator of angiogenesis‐dependent dormancy in sarcoma), in in vivo models of myxoid liposarcomas, in vitro cell lines and primary cell cultures from patients' myxoid liposarcomas. Chromatin Immunoprecipitation analysis showed that trabectedin displaced the master regulator of adipogenesis C/EBPβ from the TSP‐1 promoter, indicating an association between the up‐regulation of TSP‐1 and induction of adipocytic differentiation program by trabectedin. We conclude that trabectedin inhibits angiogenesis through multiple mechanisms, including directly affecting endothelial cells in the tumor microenvironment—with a potentially widespread activity—and targeting tumor cells' angiogenic activity, linked to a tumor‐specific molecular alteration.
What's New?
Trabectedin is a natural product approved in Europe for the treatment of soft tissue sarcoma and relapsed ovarian cancer. While the response of myxoid liposarcoma to trabectedin is characteristically associated with vessel regression, the underlying mechanisms remain unclear. In this study, trabectedin showed antiangiogenic activity linked to the upregulation of endogenous inhibitors of angiogenesis: endothelial cell‐derived TIMP‐1 and TIMP‐2 and tumor cell‐derived TSP‐1, the latter associated with adipocytic differentiation. Such connection between differentiation and angiogenesis in myxoid liposarcoma sets the basis for new combination therapies, and points to TIMP‐1, TIMP‐2 and TSP‐1 as potential markers of tumor response to trabectedin.
The efficacy of therapeutic regimens incorporating weekly or every‐3‐weeks paclitaxel (PTX) for ovarian cancer is debated. We investigated the addition of bevacizumab in regimens of chemotherapy with ...different PTX doses and schedules in preclinical models. Treatments were cisplatin (DDP) with weekly PTX (conventional), or dose‐dense‐equi (every other day to the conventional cumulative dose), or dose‐dense‐high (total dose 1.5 times higher), with or without bevacizumab. Treatment efficacy was evaluated analyzing tumor growth in different time‐windows in two patient‐derived ovarian cancer xenografts with different sensitivity to cisplatin. Tumor progression, metastasis and survival were studied in ovarian cancer models growing orthotopically and disseminating in the mouse peritoneal cavity. Short‐term effects on cell cycle, tumor cell proliferation/apoptosis and vasculature were evaluated by flow cytometry and immunohistochemistry. PTX dose‐dense (with/without DDP) was superior to the conventional scheme in a dose‐dependent manner; the high efficacy was confirmed by the lower ratio of tumor to normal cells. All schemes benefited from bevacizumab, which reduced tumor vessels. However, DDP/PTX dose‐dense‐high (only chemotherapy) was at least as active as DDP/PTX conventional plus bevacizumab. DDP/PTX dose‐dense‐high plus bevacizumab was the most effective in delaying tumor progression, though it did not prolong mouse survival and the continuous treatment with bevacizumab was associated with a malignant disease. These findings indicate that the effect of bevacizumab in combination with chemotherapy may depend on the schedule‐dose of the treatment and help to explain the unclear benefits after bevacizumab.
What's new?
Patients with ovarian cancer typically receive platinum‐ and taxane‐based therapies; recently, bevacizumab, the monoclonal antibody against VEGF, has been incorporated into these regimens. The benefit of bevacizumab in regimens of chemotherapy incorporating dose‐dense paclitaxel (PTX) for ovarian cancer is still debated, however. Taking together the results of four preclinical trials in ovarian cancer xenograft models, here the authors found that the advantage of bevacizumab in combination regimens depends on the schedule‐dose of chemotherapy. Furthermore, the quantitative analyses of tumor growth in different time‐windows was linked to biological end‐points and provided new insights into the different outcomes.
Triple-negative breast cancer (TNBC) is an aggressive and heterogeneous subgroup of breast tumors clinically defined by the lack of estrogen, progesterone and HER2 receptors, limiting the use of the ...targeted therapies employed in other breast malignancies. Recent evidence indicates that c-MYC is a key driver of TNBC. The BET-bromodomain inhibitor OTX015 (MK-8628) has potent antiproliferative activity accompanied by c-MYC down-regulation in several tumor types, and has demonstrated synergism with the mTOR inhibitor everolimus in different models. The aim of this study was to evaluate the anti-tumor activity of OTX015 as single agent and in combination with everolimus in TNBC models. OTX015 was assayed in three human TNBC-derived cell lines, HCC1937, MDA-MB-231 and MDA-MB-468, all showing antiproliferative activity after 72 h (GI50 = 75-650 nM). This was accompanied by cell cycle arrest and decreased expression of cancer stem cells markers. However, c-MYC protein and mRNA levels were only down-regulated in MDA-MB-468 cells. Gene set enrichment analysis showed up-regulation of genes involved in epigenetic control of transcription, chromatin and the cell cycle, and down-regulation of stemness-related genes. In vitro, combination with everolimus was additive in HCC1937 and MDA-MB-231 cells, but antagonistic in MDA-MB-468 cells. In MDA-MB-231 murine xenografts, tumor mass was significantly (p < 0.05) reduced by OTX015 with respect to vehicle-treated animals (best T/C = 40.7%). Although everolimus alone was not active, the combination was more effective than OTX015 alone (best T/C = 20.7%). This work supports current clinical trials with OTX015 in TNBC (NCT02259114).
Chk1 is a conserved protein kinase originally identified in fission yeast, required to delay entry of cells with damaged or unreplicated DNA into mitosis. The requirement of Chk1 for both S and G2/M ...checkpoints has been elucidated while only few studies have connected Chk1 to the mitotic spindle checkpoint. We used a small interference RNA strategy to investigate the role of Chk1 in unstressed conditions. Chk1 depletion in U2OS human osteosarcoma cells inhibited cell proliferation and raised the percentage of cells with a 4N DNA content, which correlated with accumulation of giant polynucleated cells morphologically distinct from apoptotic cells, while no increased number of cells in G2 or mitosis could be detected. Down‐regulation of Chk1 also caused accumulation of cells in the last step of cytokinesis, and of tetraploid cells in G1 phase, which coincided with activation of p53 and increased levels of p21. In addition, Chk1‐depleted U2OS cells failed to arrest in mitosis after spindle disruption by nocodazole and showed decreased protein levels of Mad2 and BubR1. These studies show that U2OS cells lacking Chk1 undergo abnormal mitosis and fail to activate the spindle checkpoint, suggesting a role of Chk1 in this checkpoint.
It has recently been reported that a large proportion of human malignant pleural mesothelioma (MPM) cell lines and patient tissue samples present high expression of the c‐MYC oncogene. This gene ...drives several tumorigenic processes and is overexpressed in many cancers. Although c‐MYC is a strategic target to restrain cancer processes, no drugs acting as c‐MYC inhibitors are available. The novel thienotriazolodiazepine small‐molecule bromodomain inhibitor OTX015/MK‐8628 has shown potent antiproliferative activity accompanied by c‐MYC downregulation in several tumor types. This study was designed to evaluate the growth inhibitory effect of OTX015 on patient‐derived MPM473, MPM487 and MPM60 mesothelioma cell lines and its antitumor activity in three patient‐derived xenograft models, MPM473, MPM487 and MPM484, comparing it with cisplatin, gemcitabine and pemetrexed, three agents which are currently used to treat MPM in the clinic. OTX015 caused a significant delay in cell growth both in vitro and in vivo. It was the most effective drug in MPM473 xenografts and showed a similar level of activity as the most efficient treatment in the other two MPM models (gemcitabine in MPM487 and cisplatin in MPM484). In vitro studies showed that OTX015 downregulated c‐MYC protein levels in both MPM473 and MPM487 cell lines. Our findings represent the first evidence of promising therapeutic activity of OTX015 in mesothelioma.
What's new?
A large proportion of human malignant pleural mesothelioma (MPM) cell lines and patient tissue samples present high expression of the c‐MYC oncogene. While no drugs acting as c‐MYC inhibitors are available to date, the novel BET inhibitor OTX015/MK‐8628 has shown potent antiproliferative activity accompanied by c‐MYC downregulation in several tumor types. Here, the authors present the first evidence of antitumor activity of OTX015 in three novel patient‐derived MPM xenograft models, all showing significant delays in tumor growth. Downregulated c‐MYC protein levels were observed following OTX015 in vitro exposure. OTX015 may thus represent a promising therapeutic approach for MPM.
DNA Damage Induces p53-dependent Down-regulation of hCHK1 Damia, Giovanna; Sanchez, Yolanda; Erba, Eugenio ...
Journal of biological chemistry/The Journal of biological chemistry,
04/2001, Letnik:
276, Številka:
14
Journal Article
Recenzirano
Odprti dostop
The levels of the human checkpoint gene hCHK1 were measured in human cancer cells growing in vitro after treatment with the DNA damaging agent cis-dichlorodiammine platinum(II) (DDP). Treatment of ...human cancer cell lines with DDP induced a decrease in the hCHK1 protein levels starting 6 h after treatment, with a further decline at 24 and 48 h. A similar decrease in the levels of hCHK1 was found at the mRNA level by using Northern blot analysis. By using isogenic cell systems in which p53 was disrupted either by transfection with HPV-E6 or by targeted homologous recombination, we found that the DNA damage-induced down-regulation of hCHK1 was only observable in wild type p53-expressing cells, with only a minor decline in the hCHK1 levels observable 48 h after treatment in cells with disrupted p53. Similarly, treatment of mutant p53-expressing human cancer cell lines with DDP did not result in changes in the levels of hCHK1. The p53-dependent down-regulation of hCHK1 is likely to be at transcriptional levels, as suggested by the lack of down-regulation of the hCHK1 when transfected under the control of a heterologous viral promoter. In addition, p53 is able to down-regulate the luciferase activity under the control of the 5′ flanking region of the hCHK1 gene. The data suggest a strict link between p53 and hCHK1 governing the activation and repression of the G2 checkpoint in which both proteins participate.
Yondelis (Trabectedin) is a novel antitumor agent of marine origin extracted from the tunicate Ecteinascidia turbinata. This original compound is active against several human tumors including sarcoma ...and ovarian and breast adenocarcinoma, as evidenced in phase II clinical trials in advanced multitreated patients. Yondelis is a DNA minor groove binder that blocks cell cycle and interferes with inducible gene transcription in a selective manner. In this study, we investigated the immunomodulatory properties of Yondelis on leukocytes. Human blood monocytes were highly susceptible in vitro to its cytotoxic effect and underwent apoptosis at pharmacologically relevant concentrations (5 nmol/L), whereas lymphocytes were up to 5-fold less sensitive. Macrophages differentiated in vitro with macrophage colony-stimulating factor and tumor-associated macrophages (TAM), isolated from patients with ovarian cancer, were also susceptible. At subcytotoxic concentrations, Yondelis inhibited the in vitro differentiation of monocytes to macrophages. In tumor-treated patients, drug infusion caused a selective decrease of monocyte counts and of ex vivo macrophage differentiation. The in vitro production of two proinflammatory mediators, CCL2 and IL-6, was markedly reduced by Yondelis in monocytes, macrophages, TAM, and freshly isolated ovarian tumor cells. The chemokine CCL2 is the major determinant of monocyte recruitment at tumor sites, whereas IL-6 is a growth factor for ovarian tumors. In view of the protumor activity of TAM and of the strong association between chronic inflammation and cancer progression, the inhibitory effect of Yondelis on macrophage viability, differentiation, and cytokine production is likely to contribute to the antitumor activity of this agent in inflammation-associated human tumors.
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