High content drug screening for Fanconi anemia therapeutics.

BACKGROUND: Fanconi anemia is a rare disease clinically characterized by malformations, bone marrow failure and an increased risk of solid tumors and hematologic malignancies. The only therapies available are hematopoietic stem cell transplantation for bone marrow failure or leukemia, and surgical resection for solid tumors. Therefore, there is still an urgent need for new therapeutic options. With this aim, we developed a novel high-content cell-based screening assay to identify drugs with therapeutic potential in FA. RESULTS: A TALEN-mediated FANCA-deficient U2OS cell line was stably transfected with YFP-FANCD2 fusion protein. These cells were unable to form fluorescent foci or to monoubiquitinate endogenous or exogenous FANCD2 upon DNA damage and were more sensitive to mitomycin C when compared to the parental wild type counterpart. FANCA correction by retroviral infection restored the cell line's ability to form FANCD2 foci and ubiquitinate FANCD2. The feasibility of this cell-based system was interrogated in a high content screening of 3802 compounds, including a Prestwick library of 1200 FDA-approved drugs. The potential hits identified were then individually tested for their ability to rescue FANCD2 foci and monoubiquitination, and chromosomal stability in the absence of FANCA. CONCLUSIONS: While, unfortunately, none of the compounds tested were able to restore cellular FANCA-deficiency, our study shows the potential capacity to screen large compound libraries in the context of Fanconi anemia therapeutics in an optimized and cost-effective platform.

Cytokines, inducers and inhibitors modulate MMP-2 and MMP­9 secretion by human Fanconi anemia immortalized fibroblasts.

Acute myeloid leukemia and head and neck squamous cell carcinomas are the major causes of mortality and morbidity in Fanconi anemia (FA) patients. Matrix metalloproteinases (MMPs), particularly MMP-2 and MMP-9, have been implicated in tumor invasion and metastasis. Various cytokines, mitogens, growth factors, inducers and inhibitors control MMP activities. We investigated the roles of these in the regulation of MMP-2 and MMP-9 in human immortalized fibroblasts from FA. Human FA immortalized fibroblast cell lines FA-A:PD220 and FA-D2:PD20 were grown in minimum essential medium (MEM) supplemented with 15% fetal bovine serum (FBS) and antibiotics in 24-well tissue culture plates. At near confluence, the cells were washed with phosphate­buffered saline (PBS) and incubated in serum-free media with the following: phorbol 12-myristate 13-acetate (PMA) at 10-100 ng/ml; tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) at 0.1-25 ng/ml; lipopolysaccharide (LPS) at 10-100 µg/ml; epigallocatechin gallate (EGCG) and doxycycline (Dox) at 10-100 µM without and with PMA; a nutrient mixture (NM) without and with PMA at 10-1,000 µg/ml; actinomycin-D and cyclohexamide at 2 and 4 µM; retinoic acid and dexamethasone at 50 µM. After 24 h, media were removed and analyzed for MMP-2 and MMP-9 by zymography. Both FA cell lines expressed only MMP-2 and responded similarly to cytokines, mitogens, inducers and inhibitors. PMA potently stimulated MMP-9 and had a moderate effect on MMP-2. TNF-α showed variable effects on MMP-2 and significantly enhanced MMP-9. IL-1ß enhanced MMP-2 slightly and MMP-9 significantly. LPS had a moderate stimulatory effect on MMP-2 and no effect on MMP-9. EGCG, Dox and NM, without and with PMA, downregulated MMP-2 and MMP-9 expression. Actinomycin-D, retinoic acid and dexamethasone also had inhibitory effects on MMP-2. Our results showed that cytokines, mitogens and inhibitors modulated FA fibroblast MMP-2 and MMP-9 expression, suggesting the clinical use of MMP inhibitors, particularly such potent and non-toxic ones as the NM and its component EGCG in the management of FA cancers.

In vitro inhibition of matrix metalloproteinases, invasion and growth of Fanconi anemia human FANCA and FANCC lymphoblasts by nutrient mixture.

AIM: Fanconi anemia is a rare genetic disorder with high propensity for development of cancers, such as aplastic anemia, leukemia and head and neck cancers. Collagen digesting matrix metalloproteinase (MMP) enzymes have been implicated in for their role in various malignancies and to promote metastasis. Biological agents that prevent extracellular matrix digestion by the MMPs have been shown to be promising therapeutic approaches to cancer. In this study, we investigated effects of a nutrient mixture (NM) containing, ascorbic acid, lysine, proline and green tea extract, on human FANCA and FANCC lymphoblasts for viability, MMP secretion and invasion. METHODS: Human FANCA lymphoblasts GM13022 and HCS536 were challenged with NM at concentration range within 10-1000 µg/ml. Cell toxicity was assessed by Trypan blue dye exclusion test. Invasion was evaluated through Matrigel and gelatinase zymography for MMP activity. RESULTS: NM was toxic in dose dependent mode to HCS536 cells but not to GM13022 cells. GM13022 cells but not HCS536 cells exhibited MMP-9 secretion, which was inhibited by NM. Matrigel invasion was inhibited in HCS536 cells at 100 and 500 µg/ml by 27% and 93%, respectively. In GM13022 cells, the NM showed completely blocked Matrigel invasion at 500 µg/ml. CONCLUSION: NM inhibited MMP secretion and Matrigel invasion in FANCA and inhibited invasion and induced toxicity in FANCC lymphoblasts. These results suggest that the NM may have therapeutic potential in Fanconi anemia associated neoplasia.

Treatment of FANCA cells with resveratrol and N-acetylcysteine: a comparative study.

Fanconi anemia (FA) is a genetic disorder characterised by chromosome instability, cytokine ipersensibility, bone marrow failure and abnormal haematopoiesis associated with acute myelogenous leukemia. Recent reports are contributing to characterize the peculiar FA metabolism. Central to these considerations appears that cells from complementation group A (FANCA) display an altered red-ox metabolism. Consequently the possibility to improve FA phenotypical conditions with antioxidants is considered. We have characterized from the structural and biochemical point of view the response of FANCA lymphocytes to N-acetyl-cysteine (NAC) and resveratrol (RV). Surprisingly both NAC and RV failed to revert all the characteristic of FA phenotype and moreover their effects are not super imposable. Our data suggest that we must be aware of the biological effects coming from antioxidant treatment.

Modelling Fanconi anemia pathogenesis and therapeutics using integration-free patient-derived iPSCs.

Fanconi anaemia (FA) is a recessive disorder characterized by genomic instability, congenital abnormalities, cancer predisposition and bone marrow (BM) failure. However, the pathogenesis of FA is not fully understood partly due to the limitations of current disease models. Here, we derive integration free-induced pluripotent stem cells (iPSCs) from an FA patient without genetic complementation and report in situ gene correction in FA-iPSCs as well as the generation of isogenic FANCA-deficient human embryonic stem cell (ESC) lines. FA cellular phenotypes are recapitulated in iPSCs/ESCs and their adult stem/progenitor cell derivatives. By using isogenic pathogenic mutation-free controls as well as cellular and genomic tools, our model serves to facilitate the discovery of novel disease features. We validate our model as a drug-screening platform by identifying several compounds that improve hematopoietic differentiation of FA-iPSCs. These compounds are also able to rescue the hematopoietic phenotype of FA patient BM cells.

Repression of matrix metalloproteinases and inhibition of cell invasion by a nutrient mixture, containing ascorbic acid, lysine, proline, and green tea extract on human Fanconi anemia fibroblast cell lines.

AIM: Fanconi Anemia, an autosomal recessive disorder, is characterized by chromosomal abnormality leading to birth defects, progressive bone marrow failure, and a high probability of developing malignancy at an early age. Head and neck squamous cell carcinoma and myeloid leukemia are the major causes of cancer related morbidity and mortality in Fanconi anemia patients. METHODS: We investigated the effect of a nutrient mixture on Fanconi Anemia human fibroblast cell lines FA-A:PD20 and FA-A:PD220 on matrix metalloproteinase expression, invasion, cell proliferation, morphology and apoptosis. The cell lines were grown in a modified Dulbecco's Eagle medium and at near confluence were treated with the nutrient mixture at increasing doses: 0; 10; 50; 100; 500; 1000 µg/ml. The cells were also treated with PMA to induce MMP-9 expression. RESULTS: Zymography demonstrated MMP-2 and PMA-induced MMP-9 activity. The nutrient mixture inhibited expression of both, MMP-2 and MMP-9, in a dose dependent manner with virtually total inhibition observed at 500 µg/ml. Matrigel invasion was inhibited in both cells lines; with 100% inhibition for FA-A:PD20 at 500 µg/ml and 100% inhibition of FA-A:P220 cells at 100 µg/ml. H&E staining did not indicate any change in cell morphology and causes apoptosis at higher doses. CONCLUSION: Our data demonstrated that the nutrient mixture inhibited matrix metalloproteinase expression, invasion and induced apoptosis, the important parameters for cancer prevention. The results suggest that the nutrient mixture may have therapeutic potential in Fanconi Anemia associated neoplasia.

Introduction of sodium pentosan polysulfate and avoidance of urethral catheterisation: improved outcomes in children with haemorrhagic cystitis post stem cell transplant/chemotherapy.

PURPOSE: Haemorrhagic cystitis (HC) is an uncommon but potentially devastating complication of chemotherapy and bone marrow transplantation in children. We aimed to test the hypothesis that early recognition, sodium pentosan polysulfate (SPP), and avoidance of urethral catheterisation improve outcomes in children with HC. METHODS: A retrospective case note review was performed of all patients treated for HC in our hospital from 2002 to 2010. A protocol for the management of HC was introduced in 2007 advocating early detection, use of SPP, and avoidance of urethral catheterisation. Data collected on each patient included primary condition, medications at onset, blood transfusions, duration of symptoms, catheter usage, and outcome. Statistical analysis was performed using the Mann-Whitney U test, and Fisher's Exact test as appropriate, P < .05 being significant. RESULTS: Five patients were treated using protocol with 5 historical controls. There was no significant difference between the ages of the group, diagnosis, and treatment at onset of HC. In the historical group, 4 of 5 died with HC, but all recovered in the protocol group (P < .05). Blood transfusion requirements were also significantly reduced after protocol introduction (P < .05). CONCLUSION: Early identification, avoidance of urethral catheterisation, and use of SPP significantly reduces blood transfusion requirements and mortality from HC.

A novel cell-free screen identifies a potent inhibitor of the Fanconi anemia pathway.

The Fanconi Anemia (FA) DNA damage response pathway is involved in the processing of DNA interstrand crosslinks (ICLs). As such, inhibition of the FA pathway could chemosensitize FA-competent tumor cells to commonly used ICL agents like cisplatin. Moreover, suppression of the FA pathway is synthetic lethal with deficiencies in several other DNA repair pathways, suggesting that FA pathway inhibitors could be used in targeted therapies against specific tumors. To identify such inhibitors, we designed a novel in vitro screening assay utilizing Xenopus egg extracts. Using the DNA-stimulated monoubiquitylation of Xenopus FANCD2 (xFANCD2-L) as readout, a chemical library screen identified DDN (2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone) as a novel and potent FA pathway inhibitor. DDN inhibited xFANCD2-L formation in a dose-dependent manner in both extracts and human cells without disruption of the upstream FA core complex. DDN also inhibited the characteristic subnuclear FANCD2 foci formation following DNA damage. Moreover, DDN displayed a greater synergistic effect with cisplatin in a FA-proficient cancer cell line compared to its FA-deficient isogenic counterpart, suggesting that DDN might be a good lead candidate as cisplatin chemosensitizer in both FA-deficient and FA-competent tumors. This system constitutes the first cell-free screening assay for identifying compounds that inhibit the FA pathway and provides a new biochemical platform for mapping the functions of its various components with specific chemical inhibitors.

Psoralen photoinactivation of herpes simplex virus: monoadduct and cross-link repair by xeroderma pigmentosum and Fanconi's anemia cells.

Furocoumarins (psoralen and its derivatives) are used to photoinactivate a variety of viruses and cell types. In the presence of long-wavelength ultraviolet light (UVA), furocoumarins bind covalently with pyrimidine residues via a cyclobutane ring. A second photoevent allows pyrimidines located on the opposite DNA strand in an adjacent base pair to react, forming a cross-link. In the experiments in this report, psoralen photoinactivation is employed to investigate human DNA repair pathways by analyzing the ability of xeroderma pigmentosum (XP) and Fanconi's anemia (FA) cells to rescue psoraleninactivated herpes simplex virus (HSV). Comparison of several XP complementation groups and one XP variant with normal human fibroblasts demonstrates that the ability of all cells to repair damage by 4,5',8-trimethylpsoralen (TMP), a derivative that forms cross-links efficiently, is similar. However, HSV photochemically reacted with 5-methylangelicin (5-MA), an isopsoralen that forms only monoadducts, is repaired at significantly lower levels in several XP complementation groups than in control fibroblast cells, which indicates that the XP repair deficiency resides in the removal of monoadducts and not of cross-links in these cell lines. Surprisingly, the FA cells rescue both TMP- and 5-MA-treated virus with slightly greater efficiency than that observed in normal human fibroblasts.