Comparison of two vitamin D supplementation strategies in children with sickle cell disease: a randomized controlled trial

Previously, we showed that nearly 70% of children followed in our sickle cell disease (SCD) clinic were vitamin D- deficient and had low vitamin intake with poor use of supplements. We compared the change in serum 25-hydroxyvitamin D [25(OH)D], safety and clinical impact of two vitamin D supplementation regimens in children with SCD. Children (5-17 years, all genotypes) were randomized to a single bolus of vitamin D₃ (300 000 IU; n = 18) or placebo (n = 20). All children received a prescription for daily 1 000 IU vitamin D₃ . Serum 25(OH)D and calcium, urinary calcium/creatinine ratio, musculoskeletal pain, quality of life, haematology and bone markers were assessed at baseline and three months post intervention. Bolus administration led to a greater rise in 25(OH)D levels from baseline compared to placebo (20 ± 16 nmol/l vs. 2 ± 19 nmol/l; P = 0·003) and correction of vitamin D deficiency. No hypercalcaemia nor hypercalciuria occurred during the study, but more children in the bolus group experienced gastrointestinal symptoms within the first month (P = 0·04). There were no differences between groups for other outcomes. The use of a high-dose vitamin D bolus combined with daily 1 000 IU vitamin D₃ was more efficient in raising 25(OH)D levels than daily supplementation alone in children with SCD.

Association between fat-soluble nutrient status and auditory and visual related potentials in newly diagnosed non-screened infants with cystic fibrosis: A case-control study

Nutritional deficiencies often precede the diagnosis of cystic fibrosis (CF) in infants, and occur at a stage where the rapidly developing brain is more vulnerable to insult. We aim to compare fat-soluble nutrient status of newly diagnosed non-screened infants with CF to that of healthy infants, and explore the association with neurodevelopment evaluated by electroencephalography (EEG). Our results show that CF infants had lower levels of all fat-soluble vitamins and docosahexaenoic acid (DHA) compared to controls. The auditory evoked potential responses were higher in CF compared to controls whereas the visual components did not differ between groups. DHA levels were correlated with auditory evoked potential responses. Although resting state frequency power was similar between groups, we observed a negative correlation between DHA levels and low frequencies. This study emphasizes the need for long-term neurodevelopmental follow-up of CF infants and pursuing intervention strategies in the future.

GX15-070 (Obatoclax), a Bcl-2 family proteins inhibitor engenders apoptosis and pro-survival autophagy and increases Chemosensitivity in neuroblastoma

Background

Neuroblastoma (NB) is a frequent pediatric tumor associated with poor prognosis. The disregulation of Bcl-2, an anti-apoptotic protein, is crucial for the tumoral development and chemoresistance. Autophagy is also implicated in tumor cell survival and chemoresistance. The aim of our study was to demonstrate therapeutic efficiency of GX 15–070, a pan-Bcl-2 family inhibitor, used alone and in combination with conventional drugs or with hydroxychloroquine (HCQ), an autophagy inhibitor.

Methods

Five neuroblastoma cell lines were tested for the cytotoxic activity of GX 15–070 alone or in combination with cisplatin, doxorubicin, HCQ or Z-VAD-FMK a broad-spectrum caspase inhibitor. Apoptosis and autophagy levels were studied by western-blot and FACS. Orthotopic injections were performed on NOD/LtSz-scid/IL-2Rgamma null mice that were treated with either GX 15–070 alone or in combination with HCQ.

Results

Synergistic cytotoxicity was observed for the drug combination in all of the 5 neuroblastoma cell lines tested, including MYCN amplified lines and in cancer stem cells. GX 15–070 significantly increased apoptosis and autophagy in neuroblastoma cells as evidenced by increased levels of the autophagy marker, LC3-II. Inhibition of autophagy by HCQ, further increased the cytotoxicity of this combinatorial treatment, suggesting that autophagy induced by these agent plays a cytoprotective role. In vivo, GX 15–070 combined with HCQ significantly decreased the growth of the tumor and the number of distant metastases.

Conclusions

Based on the synergistic effect of HCQ and GX 15–070 observed in this study, the combination of these two drugs may be utilized as a new therapeutic approach for neuroblastoma.

Is there a relationship between vitamin D nutritional status and metabolic syndrome in childhood acute lymphoblastic leukemia survivors? A PETALE study

BACKGROUND

Treatment of childhood acute lymphoblastic leukemia (cALL) has reached unprecedented success leading to survival rates reaching 90%. This is regrettably linked to increased risk of developing long-term health-related sequels into early adulthood.

OBJECTIVE

This study aims at assessing the relationship between the vitamin D status and metabolic biomarkers in PETALE, a well-characterized cohort of cALL survivors.

RESULTS

We demonstrate that 15.9% of the study participants exhibited 3 or more metabolic syndrome (MetS) risk factors. We also show a direct relationship between s25OHD₃ and plasma HDL-Cholesterol concentrations in female but not male participants.

CONCLUSION

Our data, from a metabolically well-described cohort, support a modest role for vitamin D in lipid metabolism in childhood leukemia survivors. The major outcome of this study is the strong association between HDL-Cholesterol concentration and s25OHD₃ only in female subjects, thereby conveying vitamin D a gender-specific cardio-protective effect. cALL survivors represent a population at higher risk for secondary diseases. For this reason thorough nutritional evaluation, including vitamin D should be part of the regular follow-up.

Autophagy is associated with chemoresistance in neuroblastoma

Background

Neuroblastoma (NB) is a frequent pediatric tumor characterized by a poor prognosis where a majority of tumors progress despite intensive multimodality treatments. Autophagy, a self-degradative process in cells, could be induced by chemotherapy and be associated with chemoresistance. The aim of this study was to determine whether: 1) autophagy is present in NB, 2) chemotherapy modified its levels, and 3) its inhibition decreased chemoresistance.

Methods

Immunohistochemical stainings were performed on samples from 184 NB patients in order to verify the expression of LC3B, a specific marker for autophagy, and Beclin 1, a positive regulator of autophagy. In addition, we performed an in vitro study with six NB cell lines and six drugs (vincristine, doxorubicin, cisplatin temozolomide, LY294002 and syrolimus). Inhibition of autophagy was performed using ATG5 knockdown cells or hydroxychloroquine (HCQ). Cell survival was measured using the MTT cell proliferation assay. Autophagy was detected by monodansylcadaverine, confocal microscopy and Western blot. In vivo study with tumor xenografts in NSG mice was performed.

Results

Our results have indicated that autophagy was present at low levels in NB and was not a prognostic factor, while Beclin 1 was highly expressed in children with poor NB prognosis. However, autophagy levels increased after chemotherapy in vitro and in vivo. Tumor progression was significantly decreased in mice treated with a combination of HCQ and vincristine.

Conclusions

Taken together, autophagy is present in NB, induced by chemotherapy and associated with chemoresistance, which is significantly reduced by its inhibition. Therefore, targeting autophagy represents a very attractive approach to develop new therapeutic strategies in NB.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2906-9) contains supplementary material, which is available to authorized users.

Targeting apoptosis and autophagy by a novel bcl-2 inhibitor, GX15-070, in neuroblastoma

10048

Background: Neuroblastoma (NB) is a frequent pediatric tumor with poor prognosis. The disregulation of the anti-apoptotic protein Bcl-2 is crucial for the tumoral development and chemoresistance. Autophagy is also implicated in tumor cell survival and chemoresistance. The aim of our study was to demonstrate the in vitro and in vivo therapeutic efficiency of GX 15-070, a Bcl-2 inhibitor, used alone and in combination with conventional drugs used in the treatment of NB and hydroxychloroquine (HCQ), a known autophagy inhibitor. Methods: Using 6 NB cell lines, cell viability (MTT) assays were done at progressively increased concentrations of GX 15-070 alone or in combination with cisplatin or with Z-VAD-FMK, a broad-spectrum caspase inhibitor. Apoptosis was tested by evaluating the cleavage of caspase 3 by western blots (WB) and the Annexin V/7-AAD staining studied by FACS. To assess if autophagy was modified by GX 15-070, the cleavage of LC3 protein was tested by WB and cell survival were tested with combination of GX 15-070 and HCQ. To verify the anti-tumor activity in vivo of GX 15-070, orthotopic injections were made on NSG mice treated with GX 15-070 alone and in combination with HCQ. Results: It was observed a high sensitivity of the NB cells to GX 15-070 with increase of cell death and a potential synergistic of this molecule when it’s combined with cisplatin or HCQ. This cell death was due to apoptosis and may also be inhibited by Z-VAD-FMK. GX 15-070 alone or associated to cisplatin increased the autophagy. The in vivo study showed that GX 15-070 treatment used alone or in combination with HCQ significantly decreased the size of the tumor. Conclusions: Our results support the interest of GX 15-070 in the treatment of NB alone or in combination with classical drugs. Our studies also support that activation of apoptosis associated with inhibition of autophagy have a synergistic potential against tumoral progression and must have to be considered in further mechanistic studies for the optimization of more efficient combined therapies in the treatment of NB.

Abstract 3774: Regulation of the pro-invasive properties of neuroblastoma-stem cells by membrane type-1 matrix metalloproteinase

Neuroblastoma (NB) is an aggressive childhood cancer that represents the leading cause of cancer deaths in children. Despite aggressive therapy, more than half of the children with advanced NB usually die because of uncontrolled metastatic disease. In order to develop new therapeutic strategies to limit NB's metastatic potential, it is crucial to identify key molecular targets governing the invasive process. The study of Cancer stem cells (CSCs) may be of interest in this regard because after chemotherapy, CSCs persist in tumors and cause relapse and metastasis. We had recently demonstrated that CD133 allowed to detect CSCs in NB. Membrane type-1 matrix metalloproteinase (MT1-MMP) is important in the metastatic process and its expression was correlated with unfavourable outcome in NBs. Our preliminary data had indicated that MT1-MMP was highly expressed in CD133high NB.

The purpose of this study is to characterize the interaction between CD133 and MT1-MMP in NB and determinate the role of MT1-MMP in pro-invasive properties of CSCs. We constructed paraffin-embedded blocks of tissue microarrays (TMA) from 235 patients. In vitro experiments were performed on four established NB cell lines (SK-N-DZ, SK-N-FI and SK-N-SH and SJNB-10). We performed immunohistochemical studies on paraffin-embedded TMA sections with two antibodies (CD133, MT1-MMP). To verify correlation of expression of MT1-MMP and CD133, we realized western blot and immunofluorescence (IF) of both proteins in non treated versus treated NB cell lines. CD133high NB cells were isolated by flow cytometry. CD133high and CD133low NB cells were grown within a 3D collagen matrix and the cell migration assay was tested in collagen-coated transwells. All experiments were performed with or without an anti-MT1-MMP neutralizing antibody or GM6001, a broad-spectrum MMP inhibitor.

To assess the interaction between CD133 and MT1-MMP, lysates were subjected to immunoprecipitation (IP) using an anti-CD133 antibody, followed by immunodetection with an anti-MT1-MMP antibody. Finally, we determined which domain of MT1-MMP is involved in its interaction with CD133. Different dominant negative mutants of MT1-MMP (catalytically inactive E240A, cytoplasmic domain-deleted CΔ20 and non-phosphorylatable Y573F) were transfected into NB cells followed by an IP.

There is a correlation between MT1-MMP and CD133 expressions in tumors of patients and in cell lines. Cells selected after chemotherapy express both CD133 and MT1-MMP. CD133high cells presented higher migration and invasion properties than CD133low which were MT1-MMP dependent. IF and IP showed a colocalization and interaction between CD133 and MT1-MMP. The cytoplasmic domain of MT1-MMP seems to be responsible for the interaction with CD133.

These results contribute to a better understanding CSCs properties in NB and may be of great interest to improve new therapeutic strategies.

Citation Format: Assila Belounis, Carine Nyalendo, Sonia Cournoyer, Sarah Hadj-Mimoune, Alexandre Benoit, Elliot Lasalle, Jonathan Girard, Mona Beaunoyer, Pierre Teira, Hervé Sartelet. Regulation of the pro-invasive properties of neuroblastoma-stem cells by membrane type-1 matrix metalloproteinase. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3774. doi:10.1158/1538-7445.AM2013-3774

Preclinical study of a PARP inhibitor in neuroblastoma

9570

Background: Neuroblastoma (NB) is the most common extracranial solid tumor of childhood. In spite of many therapeutic improvements, only 60% survive long term despite aggressive combinations of multi-agent chemotherapy. In previous studies, we have demonstrated that tumor initiating cells (TIC) expressing CD133 (CD133high) in NB are more resistant to chemotherapy. Moreover, these cells express higher levels of PARP-1, a central protein involved in DNA repair. PARP-1 expression is significantly lower in NB usually showing spontaneous regression than in standard NB, suggesting an implication of PARP-1 in NB progression. The objective of this study is to determine the efficacy in vitro of AG-014699 (AG), a PARP- inhibitor, used in monotherapy or in combination to cisplatine (CP) and doxorubicine (DR), classical chemotherapeutic agents used in NB treatment, on NB cell survival. Methods: Six NB cell lines (parental or CD133high purified by flow cytometry (FACS)) were treated with AG alone or in association to CP or DR. PARP-1 ELISA protein assay was used to determine the optimal drug concentration needed to inhibit the protein. Cell survival was measured by MTT test. Western Blots were done to evaluate any apoptotic or autophagic pathway modulations. Quantification of DNA damage in treated cell was done by immunofluorescence of H2A-X protein. Results: We showed that a 4µM concentration of AG is sufficient for PARP-1 inhibition. One third of celllines presented a sensitivity to AG when used in monotherapy with an IC50 lower than 5µM. However, AG demonstrated synergistic effects when associated to DR, decreasing the IC50 by half, although none is observed when combined to CP. Sentitivity of the TIC did not appear to be more important than the bulk cells. With increasing concentration of AG, our WB showed no increase in cleaved Caspase-3 suggesting no modulation of the apoptotic pathway. However, autophagy seemed to be upregulated confirmed by an increase in cleaved LC3 II protein. Double strand breaks increased 2.5 folds when 4µM AG is added to the IC50 of DR. Conclusions: AG used in combination at potentially therapeutic doses shows promising results in NB. These results will allow for the improvement of NB treatments by introducing a new therapeutic strategy.

Preclinical study of a Bcl-2 inhibitor in neuroblastoma

9563

Background: Neurblastoma (NB) is the most common and deadly extracranial solid tumor of childhood. This malignant tumor exhibits a broad spectrum of clinical features, including spontaneous regression or maturation without any treatment or progression to metastisis leading to death. However, in spite of many therapeutic improvements, only 60% survive long term. In fact, 40% of patients with high-risk NB still relapse and eventually die of the disease despite aggressive combinations of multi-agent chemotherapy. In those cases, new therapeutic strategies must be developed. Studies have shown that BCl-2, a central anti-apoptotic protein, is over-expressed in NB. Although Bcl-2 is not a significant prognostic factor in NB, its increased expression would contribute to chemotherapy resistance. BCl-2 is also shown to be involved in the modulation of autophagy by inhibiting Beclin-1. Therefore, BCl-2 protein represents an attractive target for new therapeutic strategies in NB.The objective of this study is to determine the efficacy in vitro of Obatoclax (OB), a BCl-2 inhibitor, used in monotherapy or in combination to cisplatine (CP), a classical chemotherapeutic agent used in NB treatment, on NB cell survival. Methods: Six NB cell lines (SK-N-DZ, SK-N-FI, SK-N-SH, N91, NB8 and NB10) were treated with OB alone or in association to CP. Cell survival was measured by MTT test. Autophagy was measured by MDC test. Western Blots (WB) were done to evaluate the modulation of apoptotic and autophagic pathways in treated cells. Results: OB used in monotherapy shows promising results on NB cell lines with an average IC50 of 0.12µM. Also, OB demonstrates synergistic effects when associated to CP. The IC50 of CP treated cells varied from 3.183µM to 6.837µM but dropped from 0.003µM to 0.008µM when combined with 0.5µM of OB. Moreover, our WB show an increase in cleaved Caspase-3 and PARP-1 expression, suggesting an upregulation of apoptosis in treated cells. Autophagy is also upregulated confirmed by an increase in autophagic vacuoles and cleaved LC3 II protein. Conclusions: OB used in monotherapy or in combination at potentially therapeutic doses shows promising results in NB. These results will allow for the improvement of NB treatments by introducing a new therapeutic strategy.

Genotype analysis of tumor-initiating cells expressing CD133 in neuroblastoma

Neuroblastoma (NB) is the most common and lethal extracranial solid tumor of childhood. Despite aggressive therapy, more than half of the children with advanced NB will die of uncontrolled metastatic disease. After chemotherapy, tumor-initiating cells (TICs) could persist, cause relapses and metastasis. The aim of this study is to demonstrate the tumor-initiating properties of CD133high NB cells and to identify new specific genetic abnormalities. Isolation of the CD133high cell population from NB cell lines was followed by neurosphere formation, soft agar assays, and orthotopic injections in NOD/SCID/IL2Rγc-null mice. A differential genotyping analysis was performed with Affymetrix SNP 6.0 arrays on CD133low and CD133high populations and the frequency of the abnormalities of 36 NB tumors was determined. Our results show that CD133high NB cells possess tumor-initiating properties, as CD133high cells formed significantly more neurospheres and produced significantly more colonies in soft agar than CD133low. Injection of 500 CD133high cells was sufficient to generate primary tumors and frequent metastases in mice. Differential genotyping analysis demonstrated two common regions with gains (16p13.3 and 19p13.3) including the gene EFNA2 in the CD133high population, and two with loss of heterozygosity (16q12.1 and 21q21.3) in the CD133low population. The gain of EFNA2 correlated with increased expression of the corresponding protein. These abnormalities were found in NB samples and some were significantly correlated with CD133 expression. Our results show that CD133high NB cells have TICs properties and present different genotyping characteristics compared to CD133low cells. Our findings reveal insights into new therapeutic targets in NB TICs.

Abstract 2477: Autophagy is correlated with chemoresistance in neuroblastoma

Neuroblastoma (NB) is a frequent pediatric tumor. After combined treatments of chemotherapy, bone marrow transplantation, surgery and/or radiotherapy, metastatic NBs still have a poor prognosis. Therefore, finding new therapeutic strategies to increase the survival rate of patients with NB is essential. Autophagy is a self-degradative process induced primarily by starvation and, with the intermediate of lysosomes, damaged macromolecules and cell organelles are degraded. This degradation insures cell survival by adapting to stress conditions. In addition, recent studies proposed that autophagy may contribute to cancer resistance to chemotherapy and radiotherapy. However, in some circumstances, autophagy can induce non-apoptotic programmed cell death. The aim of this study is to determine how autophagy is regulated and whether it is associated with chemoresistance in NB. Firstly, tissue Microarray blocks containing 184 patients NB were used for an immunohistochemistry study in order to identify the expression of LC3, a cytosolic protein required for autophagic vacuole (autophagosome) formation, and beclin 1, a positive regulator of autophagy. Secondly, in vitro and in vivo (NOD/SCID/IL2Rαc-null mice) studies were performed to determine the level of autophagy in NB cells following chemotherapy. Finally, autophagy was inhibited in NB cells with shRNA targeting Atg5 (an essential protein for autophagy) or with hydroxychloroquine (HCQ), a pharmacological inhibitor of autophagy. NB cells were further treated with conventional drugs used in NB treatments to evaluate if they retain their ability to resist to chemotherapy. Cell survival was measured using MTT cell proliferation assay. Autophagy was detected by labelling the autophagic vacuoles with monodansylcadaverine (MDC) and by Western blot analysis of LC3 cleavage and Atg5 expression. Our study demonstrated that autophagy is present at low levels in a majority of NB. LC3 expression was not correlated with any clinical pathological data. On the other hand, Beclin1 expression in NB was higher in children older than one year of age who have a poor prognosis. Also, it had a higher level in primitive tumors than in metastases. In our in vitro and in vivo studies, autophagy, which was detected by cleavage of LC3 and by MDC test, was correlated with increasing concentrations of therapeutic agents. Interestingly, inhibition of autophagy with either Atg5 shRNA or HCQ strongly increased the sensitivity of NB cells to chemotherapy.Overall, these results suggest that autophagy contributes to NB cells resistance to chemotherapy. Therefore, inhibition of autophagy in combination with current treatments may be of great interest in order to improve therapeutic strategies of NB.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2477. doi:1538-7445.AM2012-2477

Description of a new xenograft model of metastatic neuroblastoma using NOD/SCID/Il2rg null (NSG) mice

In order to develop a relevant xenogenic animal model of neuroblastoma (NB), we compared the tumorigenicity and metastatic potential of SK-N-SH and SK-N-DZ NB cell lines in nude mice and NOD/SCID Il2rg null (NSG) mice. Subcutaneous injection of cell lines induced tumor formation only in NSG mice and was accompanied by metastasis to the liver, adrenal glands, skull and bone marrow. NSG mice injected intravenously showed a profile of distant metastasis that was not observed in nude mice. In addition, tumor growth rates and organ infiltration patterns associated with injected NB cell lines correlated with the in vitro proliferation properties and genetic markers of poor prognosis in NB patients. We also showed that cisplatin chemotherapy was able to inhibit tumor growth. These results clearly demonstrate the higher tumorigenic and metastatic potential of NB cells in NSG mice. Therefore, this xenograft NB model should prove useful in testing the efficacy of new therapeutic approaches for NB.

Abstract 4344: Membrane-type 1 matrix metalloproteinase-mediated pro-invasive properties of neuroblastoma initiating cells

Introduction. Neuroblastoma is the most common and deadly extracranial solid tumour of childhood. Unlike localized neuroblastomas which have generally good prognosis, metastatic stages are associated with poor outcome. In this context, increasing evidences suggest that neuroblastoma may contain tumor-initiating cells (TICs) that cause relapse and metastasis. Our recent work indicates that CD133, a putative marker of TICs in various cancers, is associated with chemoresistance and poor outcome in neuroblastoma. In addition, we and others have demonstrated that membrane-type 1 matrix metalloproteinase (MT1-MMP) is associated with neuroblastoma progression and metastasis.

Purpose. The purpose of this study was to characterize the tumor-initiating properties of CD133high neuroblastoma cells and determinate the role of MT1-MMP in pro-invasive properties of these cells.

Methods/Results. Following CD133high cells selection from neuroblastoma cell lines (SK-N-DZ, SK-N-FI, SK-N-SH and SJ-NB10) with FACSAria cell sorter, we have examined their tumor-initiating features with neurosphere-forming assay in serum-free medium, colony-forming assay in soft agar and orthotopic transplantation into the adrenal gland (major site of primary neuroblastoma) of severe immunocompromised NOD/SCID/IL2Rγ- mice (NSG). Contrary to their counterpart CD133low, CD133high cells formed more colonies in soft agar and develop more neurospheres. Interestingly, orthotopic transplantation of as few as 500 CD133high cells into NSG mice resulted in tumor formation into the adrenal gland and dissemination to liver, lungs, brain and bone marrow, while matched control CD133low presented no tumor, suggesting that CD133high cells are TICs in neuroblastoma. Further western blot analyses of neuroblastoma cell lines revealed that CD133 expression correlated with that of MT1-MMP. In addition, CD133high cells growth within three-dimensional type I collagen matrices was markedly higher than CD133low cells and was significantly reduced by anti-MT1-MMP neutralizing antibodies. In the same vein, we performed cell migration assay in Boyden chamber and observed that CD133high cells exhibit more migratory abilities that CD133low cells, this migration being inhibited by anti-MT1-MMP neutralizing antibodies.

Conclusions. Altogether, these findings strongly suggest that CD133-expressing TICs of neuroblastoma exhibit high pro-invasive capacities, requiring the involvement of MT1-MMP. Targeting pro-invasive capacities of neuroblastoma TICs with MMPs-activaed pro-drugs in combination with conventional therapy, represents an attractive therapeutic strategy aimed at eliminating both neuroblastoma TICs and the bulk of the tumour.

Acknowledgment. Fondation Centre de cancérologie Charles-Bruneau.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4344. doi:10.1158/1538-7445.AM2011-4344

Inhibition of membrane-type 1 matrix metalloproteinase tyrosine phosphorylation blocks tumor progression in mice

We recently reported that membrane-type 1 matrix metalloproteinase (MT1-MMP) is phosphorylated on its unique cytoplasmic tyrosine residue but the contribution of this event to tumor progression remains unclear. In this work, we show that the non phosphorylizable cell-permeable peptide antennapedia-coupled cytoplasmic MMP-14 (ACM-14), consisting of the mutated (Y573F) cytoplasmic domain of MT1-MMP coupled to antennapedia, inhibits tyrosine phosphorylation of the enzyme and markedly reduces tumor cell proliferation within 3D type I collagen matrices. Interestingly, administration of ACM-14 to mice markedly delays tumor progression and increases survival, these antitumor actions being associated with the induction of extensive tumor necrosis. Overall, these findings suggest that inhibition of MT1-MMP tyrosine phosphorylation may represent an attractive strategy for the development of novel anticancer drugs.

Identification of membrane-type 1 matrix metalloproteinase tyrosine phosphorylation in association with neuroblastoma progression

Background

Neuroblastoma is a pediatric tumor of neural crest cells that is clinically characterized by its variable evolution, from spontaneous regression to malignancy. Despite many advances in neuroblastoma research, 60% of neuroblastoma, which are essentially metastatic cases, are associated with poor clinical outcome due to the lack of effectiveness of current therapeutic strategies. Membrane-type 1 matrix metalloproteinase (MT1-MMP, MMP-14), an enzyme involved in several steps in tumor progression, has previously been shown to be associated with poor clinical outcome for neuroblastoma. Based on our recent demonstration that MT1-MMP phosphorylation is involved in the growth of fibrosarcoma tumors, we examined the potential role of phosphorylated MT1-MMP in neuroblastoma progression.

Methods

Tyrosine phosphorylated MT1-MMP was immunostained on tissue microarray samples from 55 patients with neuroblastoma detected by mass screening (known to be predominantly associated with favourable outcome), and from 234 patients with standard diagnosed neuroblastoma. In addition, the effects of a non phosphorylable version of MT1-MMP on neuroblastoma cell migration and proliferation were investigated within three-dimensional collagen matrices.

Results

Although there is no correlation between the extent of tyrosine phosphorylation of MT1-MMP (pMT1-MMP) and MYCN amplification or clinical stage, we observed greater phosphorylation of pMT1-MMP in standard neuroblastoma, while it is less evident in neuroblastoma from mass screening samples (P = 0.0006) or in neuroblastoma samples from patients younger than one year (P = 0.0002). In vitro experiments showed that overexpression of a non-phosphorylable version of MT1-MMP reduced MT1-MMP-mediated neuroblastoma cell migration and proliferation within a three-dimensional type I collagen matrix, suggesting a role for the phosphorylated enzyme in the invasive properties of neuroblastoma cells.

Conclusion

Overall, these results suggest that tyrosine phosphorylated MT1-MMP plays an important role in neuroblastoma progression and that its expression is preferentially observed in tumor specimens from neuroblastoma patients showing poor clinical outcome.

Membrane-type 1 matrix metalloproteinase stimulates cell migration through epidermal growth factor receptor transactivation

Proteolysis of extracellular matrix proteins by membrane-type 1 matrix metalloproteinase (MT1-MMP) plays a pivotal role in tumor and endothelial cell migration. In addition to its proteolytic activity, several studies indicate that the proinvasive properties of MT1-MMP also involve its short cytoplasmic domain, but the specific mechanisms mediating this function have yet to be fully elucidated. Having previously shown that the serum factor sphingosine 1-phosphate stimulates MT1-MMP promigratory function through a process that involves its cytoplasmic domain, we now extend these findings to show that this cooperative interaction is permissive to cellular migration through MT1-MMP-dependent transactivation of the epidermal growth factor receptor (EGFR). In the presence of sphingosine 1-phosphate, MT1-MMP stimulates EGFR transactivation through a process that is dependent upon the cytoplasmic domain of the enzyme but not its catalytic activity. The MT1-MMP-induced EGFR transactivation also involves G(i) protein signaling and Src activities and leads to enhanced cellular migration through downstream extracellular signal-regulated kinase activation. The present study, thus, elucidates a novel role of MT1-MMP in signaling events mediating EGFR transactivation and provides the first evidence of a crucial role of this receptor activity in MT1-MMP promigratory function. Taken together, our results suggest that the inhibition of EGFR may represent a novel target to inhibit MT1-MMP-dependent processes associated with tumor cell invasion and angiogenesis.

Src-dependent phosphorylation of membrane type I matrix metalloproteinase on cytoplasmic tyrosine 573: role in endothelial and tumor cell migration

Membrane type 1 matrix metalloproteinase (MT1-MMP) is a transmembrane MMP that plays important roles in migratory processes underlying tumor invasion and angiogenesis. In addition to its matrix degrading activity, MT1-MMP also contains a short cytoplasmic domain whose involvement in cell locomotion seems important but remains poorly understood. In this study, we show that MT1-MMP is phosphorylated on the unique tyrosine residue located within this cytoplasmic sequence (Tyr(573)) and that this phosphorylation requires the kinase Src. Using phosphospecific antibodies recognizing MT1-MMP phosphorylated on Tyr(573), we observed that tyrosine phosphorylation of the enzyme is rapidly induced upon stimulation of tumor and endothelial cells with the platelet-derived chemoattractant sphingosine-1-phosphate, suggesting a role in migration triggered by this lysophospholipid. Accordingly, overexpression of a nonphosphorylable MT1-MMP mutant (Y573F) blocked sphingosine-1-phosphate-induced migration of Human umbilical vein endothelial cells and HT-1080 (human fibrosarcoma) cells and failed to stimulate migration of cells lacking the enzyme (bovine aortic endothelial cells). Altogether, these findings strongly suggest that the Src-dependent tyrosine phosphorylation of MT1-MMP plays a key role in cell migration and further emphasize the importance of the cytoplasmic domain of the enzyme in this process.

Src-mediated tyrosine phosphorylation of caveolin-1 induces its association with membrane type 1 matrix metalloproteinase

We have recently shown that stimulation of endothelial cells with vascular endothelial growth factor (VEGF) induces dissociation of caveolin-1 from the VEGFR-2 receptor, followed by Src family kinase-dependent tyrosine phosphorylation of the protein (Labrecque, L., Royal, I., Surprenant, D. S., Patterson, C., Gingras, D., and Beliveau, R. (2003) Mol. Biol. Cell 14, 334-347). In this study, we provide evidence that the VEGF-dependent tyrosine phosphorylation of caveolin-1 induces interaction of the protein with the membrane-type 1 matrix metalloproteinase (MT1-MMP). This interaction requires the phosphorylation of caveolin-1 on tyrosine 14 by members of the Src family of protein kinases, such as Src and Fyn, because it is completely abolished by expression of a catalytically inactive Src mutant or by site-directed mutagenesis of tyrosine 14 of caveolin-1. Most interestingly, the association of MT1-MMP with phosphorylated caveolin-1 induced the recruitment of Src and a concomitant inhibition of the kinase activity of the enzyme, suggesting that this complex may be involved in the negative regulation of Src activity. The association of MT1-MMP with phosphorylated caveolin-1 occurs in caveolae membranes and involves the cytoplasmic domain of MT1-MMP because it was markedly reduced by mutation of Cys574 and Val582 residues of the cytoplasmic tail of the enzyme. Most interestingly, the reduction of the interaction between MT1-MMP and caveolin-1 by using these mutants also decreases MT1-MMP-dependent cell locomotion. Overall these results indicate that MT1-MMP associates with tyrosine-phosphorylated caveolin-1 and that this complex may play an important role in MT1-MMP regulation and function.

Activation of tissue plasminogen activator gene transcription by Neovastat, a multifunctional antiangiogenic agent

We recently reported that Neovastat, an antiangiogenic drug that is currently undergoing Phase III clinical trials for the treatment of non-small cell lung cancer, may inhibit angiogenesis through an increase in tPA activity. Here, we show that Neovastat also stimulates tPA gene transcription in endothelial cells, in a TNFalpha-like manner. RT-PCR analysis and gene reporter assays using the human tPA promoter indicated that upregulation of the tPA gene transcription by both Neovastat and TNFalpha was correlated with the phosphorylation of JNK1/2 and of IkappaB and that SP600125 and BAY11-7082, inhibitors of JNK and IkappaK, respectively, inhibit the increase of tPA gene transcription induced by Neovastat and TNFalpha. These results suggest that Neovastat induces tPA gene transcription through activation of the JNK and NFkappaB signaling pathways, leading to an increase of tPA secretion by endothelial cells. This may lead to the localized destruction of the fibrin provisional matrix that is necessary for neovessel formation and thus contribute to the reported antiangiogenic properties of this compound.

Activation of tissue plasminogen activator gene transcription by Neovastat, a multifunctional antiangiogenic agent

We recently reported that Neovastat, an antiangiogenic drug that is currently undergoing Phase III clinical trials for the treatment of non-small cell lung cancer, may inhibit angiogenesis through an increase in tPA activity. Here, we show that Neovastat also stimulates tPA gene transcription in endothelial cells, in a TNFalpha-like manner. RT-PCR analysis and gene reporter assays using the human tPA promoter indicated that upregulation of the tPA gene transcription by both Neovastat and TNFalpha was correlated with the phosphorylation of JNK1/2 and of IkappaB and that SP600125 and BAY11-7082, inhibitors of JNK and IkappaK, respectively, inhibit the increase of tPA gene transcription induced by Neovastat and TNFalpha. These results suggest that Neovastat induces tPA gene transcription through activation of the JNK and NFkappaB signaling pathways, leading to an increase of tPA secretion by endothelial cells. This may lead to the localized destruction of the fibrin provisional matrix that is necessary for neovessel formation and thus contribute to the reported antiangiogenic properties of this compound.

The Antiangiogenic Agent Neovastat (Æ-941) Stimulates Tissue Plasminogen Activator Activity

The plasminogen activator/plasmin system represents a key component of the proteolytic machinery underlying angiogenesis. In this work, we investigated the effect of Neovastat (AE-941), a naturally occurring multifunctional antiangiogenic agent that is currently in Phase III clinical trials, on tissue and urokinase plasminogen activator activities. We found that in vitro, Neovastat at 100 microg/ml markedly stimulates t-PA-mediated plasmin generation, while it slightly inhibits the generation of plasmin mediated by uPA. The stimulatory effect of Neovastat on t-PA activity was markedly increased by a heat treatment, resulting in a 15-fold increase in the rate of activation of plasminogen. Neovastat did not directly stimulate the activity of t-PA or plasmin towards exogenous substrates, suggesting that its effect requires the presence of plasminogen. Accordingly, kinetic analysis showed that Neovastat increases both the k(cat) of t-PA as well as its affinity for plasminogen by 10-fold. The stimulation of t-PA activity by Neovastat was also correlated with a direct interaction of Neovastat with plasminogen as monitored by the surface plasmon resonance technology. Overall, these results identify Neovastat as a potent stimulator of t-PA-dependent activation of plasminogen, further emphasizing its pleiotropic mechanism of action on several molecular events involved in angiogenesis.