[show abstract][hide abstract] ABSTRACT: Musashi-1 (Msi-1) is a well-established stem cell marker in both normal and malignant colon cells and it acts by positively regulating the Notch pathway through inactivation of Numb, a Notch signalling repressor. To date, the mechanisms of regulation of Msi-1 levels remain largely unknown. Here we investigated the regulation of Msi-1 by Notch signalling in the colorectal cancer cell lines MICOL-14tum and LoVo and in primary cultures of colorectal cancer (CRC) metastases. Stimulation by the Notch ligand DLL4 was associated with an increase of Msi-1 mRNA and protein levels, and this phenomenon was prevented by the addition of antibody neutralizing Notch2/3 but not Notch1. Moreover, forced expression of activated Notch3 increased Msi-1 levels, whereas silencing of Notch3 by shRNA reduced Msi-1 levels in both CRC cells and tumor xenografts. Consistent with these findings, forced Notch3 expression or stimulation by DLL4 increased levels of activated Notch1 in MICOL-14tum and LoVo cells. Finally, treatment of CRC cells with anti-Notch2/3 antibody increased Numb protein while significantly reducing formation of spheroids in both MICOL-14tum cells and primary tumor cultures. This novel feed-forward circuit involving DLL4, Notch3, Msi-1, Numb and Notch1 may be relevant for regulation of Notch signalling in physiological processes as well as in tumor development. With regard to therapeutic implications, Notch3-specific drugs could represent a valuable strategy to limit Notch signaling in the context of colorectal cancers overexpressing this receptor.
[show abstract][hide abstract] ABSTRACT: Temozolomide (TMZ) administered daily with radiation therapy (RT) for 6 weeks, followed by adjuvant TMZ for 6 cycles, is the standard therapy for newly diagnosed glioblastoma (GBM) patients. Although TMZ is considered to be a safe drug, it has been demonstrated to cause severe myelotoxicity; in particular, some case reports and small series studies have reported severe myelotoxicity developing during TMZ and concomitant RT. We performed a prospective study to analyze the incidence of early severe myelotoxicity and its possible clinical and genetic factors.
From November 2010 to July 2012, newly diagnosed GBM patients were enrolled. They were eligible for the study if they met the following criteria: pathologically proven GBM, age 18 years and older, an Eastern Cooperative Oncology Group performance status of 0 to 2, adequate renal and hepatic function, and adequate blood cell counts before starting TMZ plus RT. Grading of hematologic toxicity developing during radiation and TMZ was based on the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. Clinical factors from all patients were recorded. The methylation status and polymorphic variants of O-methylguanine-DNAmethyl-transferase gene in peripheral blood mononuclear cells, and polymorphic genetic variants of genes involved in the pharmacokinetics and pharmacodynamics of TMZ, were analyzed. For genetic analyses, patients with toxicity were matched (1:2) for age, performance status, anticonvulsants, and proton pump inhibitors with patients without myelotoxicity.
We enrolled 87 consecutive GBM patients: 32 women and 55 men; the average age was 60 years. During TMZ and RT, 4 patients (5%) showed grade 3-4 myelotoxicity, and its median duration was 255 days. Predictor factors of severe myelotoxicity were female sex, pretreatment platelet count of ≤3,00,000/mm, methylated O-methylguanine-DNA methyltransferase promoter in the hematopoietic cell system, and specific polymorphic variants of the cytochrome P450 oxidoreductase and methionine adenosyltransferase 1A genes.
Although we studied a small population, we suggest that both clinical and genetic factors might simultaneously be associated with severe myelosuppression developed during TMZ plus RT. However, our results deserve validation in larger prospective studies and, if the factors associated with severe myelotoxicity are validated, dose adjustments of TMZ for those patients may reduce the risk of severe myelotoxicity during the concomitant treatment.
American journal of clinical oncology 09/2013; · 2.21 Impact Factor
[show abstract][hide abstract] ABSTRACT: At present, no consensus exists on the beneficial effect of preoperative cisplatin/5-fluorouracil (5-FU)-based chemotherapy versus primary surgery in the management of patients with esophageal cancer. The aim of this study was to evaluate the impact of some relevant genetic polymorphisms, within drug-related and DNA repair genes, on the clinical outcome of esophageal cancer patients subjected to cisplatin/5-FU-based neoadjuvant treatment.
DNA from 143 esophageal cancer patients, 63 receiving neoadjuvant therapy and 80 receiving primary surgery, was analyzed for the following polymorphisms: the GSTM1 null, GSTT1 null, and GSTP1 Ile105Val (rs16953) in glutathione S-transferase (GST) family, 2 in thymidylate synthase (TS) gene, and the ERCC1 Asn118Asn (rs11615), ERCC1 C8092A (rs3212986), XPD/ERCC2 Asp312Asn (rs1799793), and XPD/ERCC2 Lys751Gln (rs13181) of the nucleotide excision repair pathway.
We found that the ERCC1 rs3212986, although not associated with therapeutic response, is an independent predictive marker of better outcome in a cisplatin/5-FU-based neoadjuvant setting (hazard ratio: 0.38, 95% confidence interval: 0.2-0.73, P=0.008). In contrast, no association with clinical outcome was observed for this polymorphism in the primary surgery group.
Our study indicates the ERCC1 rs3212986 as a predictive marker in the cisplatin/5-FU-based neoadjuvant setting, and also suggests its use as a marker to select the appropriate therapeutic approach in esophageal cancer patients.
Pharmacogenetics and Genomics 08/2013; · 3.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: T acute lymphoblastic leukemia (T-ALL) is characterized by several genetic alterations and poor prognosis in about 20-25% of patients. Notably, about 60% of T-ALL shows increased Notch1 activity, due to activating NOTCH1 mutations, or alterations in the FBW7 gene, which confer to the cell a strong growth advantage. Therapeutic targeting of Notch signaling could be clinically relevant, especially for chemotherapy refractory patients. This study investigated the therapeutic efficacy of a novel anti-Notch1 monoclonal antibody by taking advantage of a collection of pediatric T-ALL engrafted systemically in NOD/SCID mice and genetically characterized with respect to NOTCH1/FBW7 mutations. Anti-Notch1 treatment greatly delayed engraftment of T-ALL cells bearing Notch1 mutations, including samples derived from poor responders or relapsed patients. Notably, the therapeutic efficacy of anti-Notch1 therapy was significantly enhanced in combination with dexamethasone. Anti-Notch1 treatment increased T-ALL cell apoptosis, decreased proliferation and caused strong inhibitory effects on Notch target genes expression along with complex modulations of gene expression profiles involving cell metabolism. Serial transplantation experiments suggested that anti-Notch1 therapy could compromise leukemia initiating cell functions. These results show therapeutic efficacy of Notch1 blockade for T-ALL, highlight the potential of combination with dexamethasone and identify surrogate biomarkers of the therapeutic response.Leukemia accepted article preview online, 18 June 2013; doi:10.1038/leu.2013.183.
Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 06/2013; · 10.16 Impact Factor
[show abstract][hide abstract] ABSTRACT: PURPOSE: 5-fluorouracil (5-FU) has been widely used since the 1980s, and it remains the backbone of many chemotherapeutic combination regimens. However, its use is often limited by the occurrence of severe toxicity. Although several reports have shown the detrimental effect of some dihydropyrimidine dehydrogenase (DPYD) and thymidylate synthase (TYMS) gene polymorphisms in patients undergoing 5-FU-based treatment, they account for only a minority of toxicities. METHODS: Looking for new candidate genetic variants associated with 5-FU-induced toxicity, we used the innovative genotyping microarray Affymetrix Drug-Metabolizing Enzymes and Transporters (DMET)™ Plus GeneChip that interrogates 1,936 genetic variants distributed in 231 genes involved in drug metabolism, excretion, and transport. To reduce variability, we analyzed samples from colorectal cancer patients who underwent fairly homogenous treatments (i.e., Machover or Folfox) and experienced G3 or G4 toxicity; control patients were matched for therapy and selected from those who did not disclose toxicity (G0-G1). RESULTS: Pharmacogenetic genotyping showed no significant difference in DPYD and TYMS genetic variants distribution between cases and controls. However, other polymorphisms could account for 5-FU-induced toxicity, with the CHST1 rs9787901 and GSTM3 rs1799735 having the strongest association. CONCLUSIONS: Although exploratory, this study suggests that genetic polymorphisms not directly related to 5-FU pharmacokinetics and pharmacodynamics are involved in 5-FU-induced toxicity. Our data also indicates DMET™ microarray as a valid approach to discover new genetic determinants influencing chemotherapy-induced toxicity.
Cancer Chemotherapy and Pharmacology 06/2013; · 2.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background:Recently, we developed an apoptotic assay for expanding the monitoring capabilities of the circulating tumour cells (CTC) test during therapy. An automated platform for computing CTCs was integrated with a mAb (M30) targeting a neoepitope disclosed by caspase cleavage at cytokeratin 18 in early apoptosis; we showed that live CTCs were associated with progression, consistent with enhanced cell migration and invasion. The test was first applied here to mRCC.Methods:Live/apoptotic CTCs changes were measured in mRCC patients receiving first-line Sunitinib and compared with circulating endothelial cell (CEC) levels.Results:The presence of EpCAM-positive, live CTCs predicts progression in individual mRCC patient, being associated with distant metastasis under first-line Sunitinib. Synchronous detection of CTCs and CEC levels discloses for the first time an association between their dynamic changes and outcome: a rapid increase of the CEC number as early as the first cycle of therapy is associated with CTC decrease in non-progressed patients, whereas a delayed response of CECs is related to higher CTC values in the progressed group indicating treatment failure.Conclusion:We demonstrated that a delayed response to antiangiogenic treatment indicated by persistent detection of CECs correlates with persistent live CTCs and more aggressive disease.
British Journal of Cancer 09/2012; 107(8):1286-94. · 5.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: BACKGROUND AND AIM: Colon crypts are characterized by a hierarchy of cells distributed along the crypt axis. Aim of this paper was to develop an in vitro system for separation of epithelial cell subsets in different maturation stages from normal human colon. METHODOLOGY AND MAJOR FINDINGS: Dissociated colonic epithelial cells were stained with PKH26, which allows identification of distinct populations based on their proliferation rate, and cultured in vitro in the absence of serum. The cytofluorimetric expression of CK20, Msi-1 and Lgr5 was studied. The mRNA levels of several stemness-associated genes were also compared in cultured cell populations and in three colon crypt populations isolated by microdissection. A PKH(pos) population survived in culture and formed spheroids; this population included subsets with slow (PKH(high)) and rapid (PKH(low)) replicative rates. Molecular analysis revealed higher mRNA levels of both Msi-1 and Lgr-5 in PKH(high) cells; by cytofluorimetric analysis, Msi-1(+)/Lgr5(+) cells were only found within PKH(high) cells, whereas Msi-1(+)/Lgr5(-) cells were also observed in the PKH(low) population. As judged by qRT-PCR analysis, the expression of several stemness-associated markers (Bmi-1, EphB2, EpCAM, ALDH1) was highly enriched in Msi-1(+)/Lgr5(+) cells. While CK20 expression was mainly found in PKH(low) and PKH(neg) cells, a small PKH(high) subset co-expressed both CK20 and Msi-1, but not Lgr5; cells with these properties also expressed Mucin, and could be identified in vivo in colon crypts. These results mirrored those found in cells isolated from different crypt portions by microdissection, and based on proliferation rates and marker expression they allowed to define several subsets at different maturation stages: PKH(high)/Lgr5(+)/Msi-1(+)/CK20(-), PKH(high)/Lgr5(-)/Msi-1(+)/CK20(+), PKH(low)/Lgr5(-)/Msi-1(+)/Ck20(-), and PKH(low)/Lgr5(-)/Msi-1(-)/CK20(+) cells. CONCLUSIONS: Our data show the possibility of deriving in vitro, without any selection strategy, several distinct cell subsets of human colon epithelial cells, which recapitulate the phenotypic and molecular profile of cells in a discrete crypt location.
PLoS ONE 01/2012; 7(8):e43379. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: We report multiplex ligation-dependent probe amplification analysis (MLPA) of DNA copy number alterations in 59 esophageal cancer samples, stratified by histotype. Results showed that squamous cell carcinoma (SCC) samples present clustered abnormalities with several genes altered at high frequency. Instead, esophageal adenocarcinoma (ADC) samples are characterized by a more widespread genomic instability, and in these patients total DNA copy number alterations resulted to be an independent prognostic factor. The detection of characteristic molecular changes represents a step towards a better understanding of the molecular basis of esophageal tumorigenesis, and might offer the potential for the discovery of tumor-specific biomarkers.
Cancer letters 11/2011; 310(1):84-93. · 4.86 Impact Factor
[show abstract][hide abstract] ABSTRACT: VEGF antagonists are now widely used cancer therapeutics, but predictive biomarkers of response or toxicity remain unavailable. In this study, we analyzed the effects of anti-VEGF therapy on tumor metabolism and therapeutic response by using an integrated set of imaging techniques, including bioluminescence metabolic imaging, 18-fluorodeoxyglucose positron emission tomography, and MRI imaging and spectroscopy. Our results revealed that anti-VEGF therapy caused a dramatic depletion of glucose and an exhaustion of ATP levels in tumors, although glucose uptake was maintained. These metabolic changes selectively accompanied the presence of large necrotic areas and partial tumor regression in highly glycolytic tumors. In addition, we found that the central metabolic protein kinase AMP-activated protein kinase (AMPK)-a cellular sensor of ATP levels that supports cell viability in response to energy stress-was activated by anti-VEGF therapy in experimental tumors. AMPK-α2 attenuation increased glucose consumption, tumor cell sensitivity to glucose starvation, and tumor necrosis following anti-VEGF therapy. Taken together, our findings reveal functional links between the Warburg effect and the AMPK pathway with therapeutic responses to VEGF neutralization in tumor xenograft models.
Cancer Research 06/2011; 71(12):4214-25. · 8.65 Impact Factor
[show abstract][hide abstract] ABSTRACT: Ontogenesis of T cells in the thymus is a complex process whose molecular control is poorly understood. The present study investigated microRNAs involved in human thymocyte differentiation by comparing the microRNA expression profiles of thymocytes at the double-positive, single-positive CD4(+) and single-positive CD8(+) maturation stages. Microarray analysis showed that each thymocyte population displays a distinct microRNA expression profile that reflects their developmental relationships. Moreover, analysis of small-RNA libraries generated from human unsorted and double-positive thymocytes and from mature peripheral CD4(+) and CD8(+) T lymphocytes, together with the microarray data, indicated a trend toward up-regulation of microRNA expression during T-cell maturation after the double-positive stage and revealed a group of microRNAs regulated during normal T-cell development, including miR-150, which is strongly up-regulated as maturation progresses. We showed that miR-150 targets NOTCH3, a member of the Notch receptor family that plays important roles both in T-cell differentiation and leukemogenesis. Forced expression of miR-150 reduces NOTCH3 levels in T-cell lines and has adverse effects on their proliferation and survival. Overall, these findings suggest that control of the Notch pathway through miR-150 may have an important impact on T-cell development and physiology.
[show abstract][hide abstract] ABSTRACT: Increased Notch1 activity has been observed in intestinal tumours, partially accomplished by β-catenin-mediated up-regulation of the Notch ligand Jagged-1. Whether further mechanisms of Notch activation exist and other Notch receptors might be involved is unclear. Microarray data indicated that Notch3 transcript levels are significantly up-regulated in primary and metastatic CRC samples compared to normal mucosa. Moreover, Notch3 protein was expressed at strong/moderate levels by 19.7% of 158 CRC samples analysed, and at weak levels by 51.2% of the samples. Intrigued by these findings, we sought to investigate whether Notch3 modulates oncogenic features of CRC cells. By exploiting xenografts of CRC cells with different tumourigenic properties in mice, we found that the aggressive phenotype was associated with altered expression of components of the Notch pathway, including Notch3, Delta-like 4 (DLL4), and Jagged-1 ligands. Stimulation with immobilized recombinant DLL4 or transduction with DLL4-expressing vectors dramatically increased Notch3 expression in CRC cells, associated with accelerated tumour growth. Forced expression of an active form of Notch3 mirrored the effects of DLL4 stimulation and increased tumour formation. Conversely, attenuation of Notch3 levels by shRNA resulted in perturbation of the cell cycle followed by reduction in cell proliferation, clonogenic capacity, and inhibition of tumour growth. Altogether, these findings indicate that Notch3 can modulate the tumourigenic properties of CRC cells and contributes to sustained Notch activity in DLL4-expressing tumours.
The Journal of Pathology 03/2011; 224(4):448-60. · 7.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: Targeting the tumor vasculature by vascular disrupting agents (VDAs) has shown therapeutic activity in mouse models. In most cases, however, VDA efficacy is substantially compromised by the inability of these drugs to completely kill tumor cells located at the periphery of the tumor mass. In this study, we investigated anti-tumor effects of L19mTNFα, a fusion protein composed of L19 (scFv), specific for the angiogenesis-associated ED-B containing fibronectin isoform, and murine TNFα, in xenograft models of esophageal cancer.
We evaluated ED-B expression in esophageal cancer samples. Subsequently, we generated subcutaneous xenografts from primary tumors, treated them with the L19mTNFα scFv, and determined effects on tumor vasculature, viability and proliferation, and VEGF expression and infiltration by hematopoietic cells. To overcome tumor resistance, L19mTNFα scFv was combined with vandetanib, a tyrosine kinase inhibitor of VEGF receptor, epidermal growth factor receptor, and RET signaling.
ED-B was broadly expressed by esophageal cancer cell lines, as well as xenografts and primary surgical samples of esophageal cancer. Administration of L19mTNFα acutely damaged tumor vasculature and increased necrosis, indicating a VDA-like activity of this immunoconjugate. This event was followed, however, by rapid tumor growth recovery associated with increased expression of VEGF and recruitment of CD11b+Gr1+ myeloid cells into tumors. Combination of L19mTNFα with vandetanib severely impaired vascular functions in tumors, leading to a reduction of cell proliferation and increased necrosis, without apparent signs of toxicity.
These findings indicate that a combination of vascular damaging agents with anti-angiogenic drugs could represent a promising therapeutic strategy for esophageal cancer.
Clinical Cancer Research 02/2011; 17(3):447-58. · 7.84 Impact Factor
[show abstract][hide abstract] ABSTRACT: Activation of the Notch pathway occurs commonly in T acute lymphoblastic leukemia (T-ALL) because of mutations in Notch1 or Fbw7 and is involved in the regulation of cell proliferation and survival. Deregulated Notch3 signalling has also been shown to promote leukemogenesis in transgenic mice, but the targets of Notch3 in human T-ALL cells remain poorly characterized. Here, we show that Notch3 controls levels of mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1). In a model of T-ALL cell dormancy, both Notch3 activation and MKP-1 expression were upregulated in aggressive compared with dormant tumors, and this inversely correlated with the levels of phosphorylated p38 and extracellular signal-regulated kinase1/2 (ERK1/2) MAPKs, two canonical MKP-1 targets. We demonstrate that MKP-1 protein levels are regulated by Notch3 in T-ALL cell lines because its silencing by RNA interference or treatment with γ-secretase inhibitors induced strong MKP-1 reduction whereas activation of Notch3 signalling had the opposite effect. Furthermore, MKP-1 has an important role in T-ALL cell survival because its attenuation by short hairpin RNA significantly increased cell death under stress conditions. This protective function has a key role in vivo, as MKP-1-deficient cells showed impaired tumorigenicity. These results elucidate a novel mechanism downstream of Notch3 that controls the survival of T-ALL cells.
Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 01/2011; 25(4):588-98. · 10.16 Impact Factor
[show abstract][hide abstract] ABSTRACT: Human T-cell leukemia virus type 1 (HTLV-1), a retrovirus that infects more than 20 million people worldwide, is the etiological agent of ATLL (adult T-cell leukemia/lymphoma), an aggressive leukemia of CD4+ T lymphocytes which arises in a small percentage of infected individuals after a long clinical latency. Tumor emergence is attributed primarily to the oncogenic activity of the viral protein Tax, which drives the expression of viral transcripts and controls the expression and function of a broad variety of host-cell genes involved in proliferation, genetic stability and apoptosis. Nevertheless, many aspects of HTLV-1 replication, persistence and pathogenesis remain to be understood. The emerging role of microRNAs in tumor development and viral infection has prompted investigations on the interactions between HTLV-1 and the microRNA regulatory network. In the present review we discuss recent data demonstrating changes in cellular microRNA expression in HTLV-1-infected cell lines and ATLL cells, and the functional impact of a subset microRNAs deregulated by HTLV-1 on cellular gene expression and signal transduction pathways. Mechanisms through which the viral proteins may influence microRNA expression are discussed. Results of searches for potential cellular microRNAs that target viral transcripts and for microRNAs produced by HTLV-1 are described. Observations along with regarding the expression of tRNA-derived small regulatory RNAs in HTLV-1-infected cells are presented.
Molecular Aspects of Medicine 10/2010; 31(5):367-82. · 10.38 Impact Factor
[show abstract][hide abstract] ABSTRACT: This study aimed to detect the M30 neoepitope on circulating tumor cells (CTC) as a tool for quantifying apoptotic CTC throughout disease course and treatment.
An automated sample preparation and analysis platform for computing CTC (CellSearch) was integrated with a monoclonal antibody (M30) targeting a neoepitope disclosed by caspase cleavage at cytokeratin 18 (CK18) in early apoptosis. The assay was validated using cell lines and blood samples from healthy volunteers and patients with epithelial cancer.
M30-positive CTC could be detected in >70% of CTC-positive carcinoma patients, which were free for both chemotherapy and radiologic treatments. The fraction of M30-positive CTC varied from 50% to 80%, depending on the histotype. To investigate the potential application of the M30 CTC assay for the evaluation of response in early phase trials, CTC and M30-positive CTC were enumerated in a small case series of breast cancer patients during treatment. Results indicate that changes in the balance of M30-negative/positive CTC may be used as a dynamic parameter indicating an active disease, as documented by consistent radiologic findings.
M30 expression on CTC is detectable by immunofluorescence. The M30-integrated test has potential for monitoring dynamic changes in the quote of apoptotic CTC (in addition to CTC count) to evaluate response in clinical trials of molecularly targeted anticancer therapeutics as well as for translational research, in which there is a pressing need for informative circulating biomarkers.
Clinical Cancer Research 10/2010; 16(21):5233-43. · 7.84 Impact Factor
[show abstract][hide abstract] ABSTRACT: Although adoptive immunotherapy with CD8(+) CTL is providing clinically relevant results against EBV-driven malignancies, the effector role of CD4(+) T cells has been poorly investigated. We addressed this issue in a lymphoblastoid cell line-induced mouse model of posttransplant lymphoproliferative disease (PTLD) by comparing the therapeutic efficacy of EBV-specific CD4(+) and CD8(+) T cell lines upon adoptive transfer. CD4(+) T cells disclosed a long-lasting and stronger proliferative potential than CD8(+) T cells, had a similar activation and differentiation marker profile, efficiently killed their targets in a MHC class II-restricted manner, and displayed a lytic machinery comparable to that of cognate CD8(+) T cells. A detailed analysis of Ag specificity revealed that CD4(+) T cells potentially target EBV early lytic cycle proteins. Nonetheless, when assessed for the relative therapeutic impact after in vivo transfer, CD4(+) T cells showed a reduced activity compared with the CD8(+) CTL counterpart. This feature was apparently due to a strong and selective downmodulation of MHC class II expression on the tumor cells surface, a phenomenon that could be reverted by the demethylating agent 5-aza-2'-deoxycytidine, thus leading to restoration of lymphoblastoid cell line recognition and killing by CD4(+) T cells, as well as to a more pronounced therapeutic activity. Conversely, immunohistochemical analysis disclosed that HLA-II expression is fully retained in human PTLD samples. Our data indicate that EBV-specific cytotoxic CD4(+) T cells are therapeutic in mice bearing PTLD-like tumors, even in the absence of CD8(+) T cells. These findings pave the way to use cultures of pure CD4(+) T cells in immunotherapeutic approaches for EBV-related malignancies.
The Journal of Immunology 04/2010; 184(10):5895-902. · 5.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: The Notch pathway is an evolutionally conserved cell-cell interaction signalling system involved in several key aspects of cell life, ranging from differentiation and proliferation to apoptosis. As such, it plays an important role in development, homeostasis, angiogenesis and various diseases. Over-activation of the Notch pathway has often been reported in cancer, leading to a variety of effects including increased proliferation, protection from apoptosis and maintenance of cancer initiating cells. Additionally, this signalling pathway has also been involved in tumor angiogenesis. The clearest example of oncogenic Notch signalling is observed in T acute lymphoblastic leukemia (T-ALL), an aggressive neoplasm of immature T-cells, due to genetic alterations leading to ligand-independent increased Notch1 receptor signalling. In solid tumors, however, extrinsic regulation through canonical cell-cell interactions appears to drive activation of the pathway. We recently found that triggering of Notch3 signalling by DLL4 expressed on angiogenic endothelial cells promotes escape of T-ALL cells from tumor dormancy in a xenograft model. This observation discloses un unsuspected role for ligand-dependent regulation of Notch receptors in T-ALL cells, suggesting that blocking extrinsic Notch activation by anti-DLL4 or other ligand-targeted drugs could represent a novel therapeutic approach for this aggressive malignancy.
[show abstract][hide abstract] ABSTRACT: Angiogenesis plays an established role in the growth promotion of dormant micrometastasis, because blood vessels deliver oxygen and nutrients into the tumor microenvironment. A discrete event termed "the angiogenic switch" has been recognized as key in promoting the transition towards a clinically aggressive tumor. This concept generally describes a permanent change in the angiogenic capacity of the tumor sustained by genetic events occurring in cancer cells. Recent evidence, however, indicates that a transient angiogenic switch delivered by components of the tumor microenvironment can also convey tumorigenic properties to tumor cells. Why is the angiogenic switch so fundamental in the promotion of tumor growth? In addition to the recognized feeding function of blood vessels, there is accumulating evidence suggesting that endothelial cells - and perhaps other cellular components of the microenvironment - communicate both positive and negative signals to tumor cells. This cross-talk between heterogeneous cell types could turn out to be important in the regulation of cancer cells' behaviour. In this review, we discuss the possible implications of the angiogenic switch on our understanding of the regulation of tumor dormancy.
Current Molecular Medicine 11/2009; 9(8):935-41. · 4.20 Impact Factor
[show abstract][hide abstract] ABSTRACT: New studies indicate that the side population (SP) and cancer stem cells (CSC) drive and maintain many types of human malignancies. SP and CSC appear to be highly resistant to chemo- and radio-therapy and this knowledge is now reshaping our therapeutic approach to cancer. Several studies have pioneered the possibility of specifically targeting CSC and SP cells by exploiting pathways involved in drug resistance, or forcing these cells to proliferate and differentiate thus converting them into a target of conventional therapies. Moreover, certain cytokines - such as IFN-alpha - appear to modulate SP and stem cell functions, and this associates with remarkable therapeutic activity in animal models. These recent findings underscore the need of a more comprehensive view of the interactions between cytokines and key regulatory pathways in SP and CSC.
Cancer letters 07/2009; 288(1):1-9. · 4.86 Impact Factor
[show abstract][hide abstract] ABSTRACT: Interferon (IFN)-alpha is a cytokine with marked therapeutic activity in transplantable tumor models, that is in part due to angiogenesis inhibition. Aim of this study was to investigate the effects of IFN-alpha during the early phases of tumor development in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model. To provide sustained IFN-alpha production, TRAMP mice were injected intraperitoneally with lentiviral vectors. IFN-alpha administration resulted in rapid and protracted upregulation of IFN-alpha-regulated genes associated with antiangiogenic and antiproliferative functions in the prostate of TRAMP mice, including guanylate-binding protein 1 (GBP-1), IFI204 and CXCL10-11. These transcriptional changes were accompanied by effects on the tumor vasculature, including significant reduction of intraductal microvessel density and increased pericyte coverage, and marked reduction of tumor cell proliferation, without induction of tumor necrosis. Intriguingly, GBP-1 and myxovirus resistance A, two IFN-regulated proteins, were found expressed in approximately 40% of human prostate cancer samples analyzed, suggesting expression of endogenous IFN-alpha. Overall, these findings demonstrate that IFN-alpha is able to counteract the angiogenic switch and impairs tumor cell proliferation in preinvasive lesions. Since the angiogenic switch also marks progression of human prostatic cancer, these results highlight the potential of angiogenesis inhibitors for the development of chemoprevention strategies in high-risk individuals.