Antitumor efficacy of the heparanase inhibitor SST0001 alone and in combination with antiangiogenic agents in the treatment of human pediatric sarcoma models.

The activity of heparanase is responsible for heparan sulfate cleavage, thus resulting in the release of heparan sulfate-bound growth factors. Since heparanase activity is upregulated in several tumor types and is implicated in the malignant behavior, the enzyme is regarded as a promising target for antitumor therapy. Based on previous evidence that the heparanase inhibitor SST0001, a non-anticoagulant N-acetylated glycol split heparin, is effective against an Ewing's sarcoma model, the present study was performed to extend the preclinical evaluation of SST0001 to a panel of pediatric sarcoma models, representative of various tumor histotypes (soft tissue and bone sarcomas) and to further elucidate its mode of action. SST0001 treatment downregulated several angiogenic factors in the conditioned media of sarcoma cells, inhibited the pro-invasive effect of heparin-binding factors (VEGF, bFGF, HGF, PDGF), and abrogated PDGF receptor tyrosine phosphorylation. Subcutaneous administration of SST0001 was very effective, resulting in a significant growth inhibition (range, 64-95%) of all tested tumor xenografts. The efficacy of SST0001 was enhanced in combination with antiangiogenic agents (bevacizumab, sunitinib) as documented by the high rate of complete response. The synergistic effect of SST0001 in combination with antiangiogenic agents is consistent with the heparanase mode of action and with the relevant role of heparin-binding proangiogenic/growth factors in the malignant behavior of sarcoma cells.

TIMP3 regulates migration, invasion and in vivo tumorigenicity of thyroid tumor cells.

Papillary thyroid carcinoma (PTC) arises from the thyroid follicular epithelium and represents the most frequent thyroid malignancy. PTC is associated with gene rearrangements generating RET/PTC and TRK oncogenes, and to the BRAFV600E activating point mutation. A role of tumor-suppressor genes in the pathogenesis of PTC has not been assessed yet. The tissue inhibitor of metalloproteinase-3 (TIMP3) gene, encoding a metalloproteinases inhibitor and capable of inhibiting growth, angiogenesis, invasion and metastasis of several cancers, was found to be silenced by promoter methylation in a consistent fraction of PTCs, in association with tumor aggressiveness and BRAFV600E mutation, thus suggesting an oncosuppressor role. To explore this possibility, in this study we performed gene expression and functional studies. Analysis of gene expression data produced in our laboratory as well as meta-analysis of publicly available data sets confirmed the downregulation of TIMP3 gene expression in PTC with respect to normal thyroid. The functional consequences of TIMP3 downregulation were investigated in the PTC-derived NIM1 cell line, in which the expression of TIMP3 is silenced. Restoration of TIMP3 expression by exposure to soluble TIMP3 protein or by complementary DNA transfection had no effect on the growth rate of NIM1 cells. Instead, it affected the adhesive, migratory and invasive capabilities of NIM1 cells by modulating several proteins involved in these processes. A striking effect was observed in vivo, as TIMP3 reduced the tumorigenicity of NIM1 cells by repressing angiogenesis and macrophage infiltration. Our data indicate that the loss of TIMP3 expression exerts a functional role in the pathogenesis of PTC.

Antitumour and antiangiogenic effects of IDN 5390, a novel C-seco taxane, in a paclitaxel-resistant human ovarian tumour xenograft.

IDN 5390 is a novel C-seco taxane analogue selected for preclinical development on the basis of its antimotility activity on endothelial cells, antitumour efficacy in a large panel of human tumour xenografts and high tolerability in mouse. On the basis of oral availability, IDN 5390 is suitable for protracted administration schedules. Such a treatment schedule has been reported as the most appropriate to exploit the antiangiogenic effects of cytotoxic drugs. An ability to downregulate angiogenesis-related growth factors in tumour cells has been described for IDN 5390. The aim of the study was to investigate the antitumour and antiangiogenic potential of oral IDN 5390 on a human ovarian carcinoma xenograft, the INT.ACP/PTX, resistant to paclitaxel (PTX). Such tumour line was derived in vivo from a cisplatin-resistant tumour line, the A2780/DDP, which is sensitive to PTX. Compared to the parental cells, INT.ACP/PTX cells exhibited a high level of Pgp expression, resulting in a reduced in vitro sensitivity to both PTX and IDN 5390. The INT.ACP/PTX tumour xenograft was still resistant to PTX, but responsive to IDN 5390, when delivered per os, by a daily prolonged schedule. A direct effect on tumour cells, allowed by the high tolerability of the compound in mouse, cannot be excluded in vivo. Immunohistochemical analysis indicated a significant reduction of microvessel density in IDN 5390-treated tumours, lasting till 7 days after the last drug administration. Thus, a prolonged inhibitory effect on tumour angiogenesis is consistent with the persistent growth control of INT.ACP/PTX tumour achieved by IDN 5390. On the contrary, the low tolerability and the limited oral availability of conventional taxanes do not allow an easy feasibility of such treatment regimen. Thus, the tolerability profile of IDN 5390 in preclinical systems and its efficacy in PTX-resistant tumours support the therapeutic interest for its clinical development, with particular attention to oral daily prolonged schedules.

The nitroxide tempol induces oxidative stress, p21(WAF1/CIP1), and cell death in HL60 cells.

The antiproliferative effect of Tempol, a stable nitroxide free radical, was investigated on the p53-negative human leukemia cell line HL60. A concentration- and time-dependent inhibition of cell growth was observed that appears to be due to induction of apoptosis. Involvement of oxidative stress is indicated by a concentration-dependent increase in intracellular peroxides and a parallel decrease in total cellular glutathione; in addition, increased survival rates were observed in cells simultaneously treated with Tempol and the antioxidant N-acetylcysteine. Tempol did not affect the relative levels of Bax and Bcl2, whereas p21(WAF1/CIP1) was enhanced in a concentration- and time-dependent fashion; this effect was partially inhibited by N-acetylcysteine, was maintained for up to 8 h after Tempol removal, and seemed to depend on continuing protein synthesis. The increase in p21(WAF1/CIP1) was accompanied by a parallel accumulation of cells in the G(1) phase of the cycle and by a decrease in the 110 kDa form of pRb. Our results suggest that p53-independent induction of p21(WAF1/CIP1) mediates the antiproliferative effect of Tempol; on the basis of this observation, the nitroxide could be proposed as an useful adjunct to the treatment of p53-deficient tumors, which are often refractory to standard chemotherapy.

New 1,4-anthracene-9,10-dione derivatives as potential anticancer agents.

The amino-substituted anthracene-9,10-dione (9,10-anthraquinone) derivatives represent one of the most important classes of potential anticancer agents. To better understand the basic rules governing DNA sequence specificity, we have recently synthesized a new class of D- and L-aminoacyl-anthraquinone derivatives. We have tested these new compounds as cytotoxic agents, and we have correlated their activity with the configuration of the chiral aminoacyl moiety. Molecular modeling studies have been performed to compare the test drugs in terms of steric overlapping.

Long term results of corneal grafting in Fuchs' endothelial dystrophy.

The long term results of grafting for Fuchs' endothelial dystrophy are reported in 25 patients with 33 penetrating keratoplasties, with a mean observation period of 50 months, 33% of the cases showed a visual acuity of 0.5 or better, while 42% had a visual acuity less than 0.1. The cause of visual acuity less than 0.1 was largely permanent corneal oedema, which was observed to develop in 39% of the cases. Some of the causes of oedema were accounted for by graft rejection, glaucoma and other obvious causes, but in a significant number of cases (12% of all cases), the oedema developed as a quiet, slowly progressive oedema without any obvious aetiology. It is tentatively suggested that the recurrence of oedema might be associated with the primary disease in patients with Fuchs' endothelial dystrophy.