Blood and lymph vessels in embryonic tumors

Potential anticancer properties and mechanisms of thymoquinone in osteosarcoma and bone metastasis

Despite great advances, therapeutic approaches of osteosarcoma, the most prevalent class of preliminary pediatric bone tumors, as well as bone-related malignancies, continue to demonstrate insufficient adequacy. In recent years, a growing trend toward applying natural bioactive compounds, particularly phytochemicals, as novel agents for cancer treatment has been observed. Bioactive phytochemicals exert their anticancer features through two main ways: they induce cytotoxic effects against cancerous cells without having any detrimental impact on normal cell macromolecules such as DNA and enzymes, while at the same time combating the oncogenic signaling axis activated in tumor cells. Thymoquinone (TQ), the most abundant bioactive compound of Nigella sativa, has received considerable attention in cancer treatment owing to its distinctive properties, including apoptosis induction, cell cycle arrest, angiogenesis and metastasis inhibition, and reactive oxygen species (ROS) generation, along with inducing immune system responses and reducing side effects of traditional chemotherapeutic drugs. The present review is focused on the characteristics and mechanisms by which TQ exerts its cytotoxic effects on bone malignancies.

Targeting microRNAs with thymoquinone: a new approach for cancer therapy

Cancer is a global disease involving transformation of normal cells into tumor types via numerous mechanisms, with mortality among all generations, in spite of the breakthroughs in chemotherapy, radiotherapy and/or surgery for cancer treatment. Since one in six deaths is due to cancer, it is one of the overriding priorities of world health. Recently, bioactive natural compounds have been widely recognized due to their therapeutic effects for treatment of various chronic disorders, notably cancer. Thymoquinone (TQ), the most valuable constituent of black cumin seeds, has shown anti-cancer characteristics in a wide range of animal models. The revolutionary findings have revealed TQ's ability to regulate microRNA (miRNA) expression, offering a promising approach for cancer therapy. MiRNAs are small noncoding RNAs that modulate gene expression by means of variation in features of mRNA. MiRNAs manage several biological processes including gene expression and cellular signaling pathways. Accordingly, miRNAs can be considered as hallmarks for cancer diagnosis, prognosis and therapy. The purpose of this study was to review the various molecular mechanisms by which TQ exerts its potential as an anti-cancer agent through modulating miRNAs.

The selective VEGFR1-3 inhibitor axitinib (AG-013736) shows antitumor activity in human neuroblastoma xenografts

Tumor angiogenesis in childhood neuroblastoma is an important prognostic factor suggesting a potential role for antiangiogenic agents in the treatment of high-risk disease. Within the KidsCancerKinome project, we evaluated the new oral selective pan-VEGFR tyrosine kinase inhibitor axitinib (AG-013736) against neuroblastoma cell lines and the subcutaneous and orthotopic xenograft model IGR-N91 derived from a primary bone marrow metastasis. Axitinib reduced cell proliferation in a dose-dependent manner with IC(50) doses between 274 and >10,000 nmol/l. Oral treatment with 30 mg/kg BID for 2 weeks in advanced tumors yielded significant tumor growth delay, with a median time to reach five times initial tumor volume of 11.4 days compared to controls (p = 0.0006) and resulted in significant reduction in bioluminescence. Simultaneous inhibition of VEGFR downstream effector mTOR using rapamycin 20 mg/kg q2d×5 did not statistically enhance tumor growth delay compared to single agent activities. Axitinib downregulated VEGFR-2 phosphorylation resulting in significantly decreased microvessel density (MVD) and overall surface fraction of tumor vessels (OSFV) in all xenografts as measured by CD34 immunohistochemical staining (mean MVD ± SD and OSFV at 14 days 21.27 ± 10.03 in treated tumors vs. 48.79 ± 17.27 in controls and 0.56% vs. 1.29%; p = 0.0006, respectively). We further explored the effects of axitinib on circulating mature endothelial cells (CECs) and endothelial progenitor cells (CEPs) measured by flow cytometry. While only transient modification was observed for CECs, CEP counts were significantly reduced during and up to 14 days after end of treatment. Axitinib has potent antiangiogenic properties that may warrant further evaluation in neuroblastoma.

[Metronomic chemotherapy in pediatric oncology: hype or hope?]

Angiogenesis is crucial for the growth of cancer. As such, it has become an established target in fighting cancer. Metronomic chemotherapy-the chronic administration of chemotherapy at relatively low, minimally toxic doses on a frequent schedule of administration at close regular intervals, with no prolonged drug-free breaks-is a potential novel approach to controlling advanced cancer disease. It is thought to work primarily through antiangiogenic mechanisms and has the property of killing resistant cancer cells while significantly reducing undesirable toxic side effects. We review the data regarding the use of metronomic chemotherapy in children with cancer and discuss its potential uses and limits.

[Potential role of antiangiogenic treatment in neuroblastoma]

Focus on new drug development over the last few years has yielded new agents that differ from unspecific classical chemotherapeutics and ionizing radiation, while still targeting the cancer cell itself. Antiangiogenesis is a totally distinct approach targeting the tumor's blood vessels. This concept has now found its eligibility for the treatment of several adult solid tumors: the human antivascular endothelial growth factor (VEGF) antibody bevacizumab, as well as the VEGF receptor tyrosine kinase inhibitors, sunitinib and sorafinib, have recently been licensed by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMEA) for the treatment of colorectal, renal, and lung cancer. Other antiangiogenic drugs are under preclinical and early clinical evaluation. However, what do we know of the use of these drugs in pediatric solid tumors, such as sarcomas and embryonal and neuronal tumors? For some time now, neuroblastoma has been shown to be dependent on angiogenesis. However, the first preclinical data on antiangiogenic drugs in neuroblastoma have not been published until recently, and clinical trials with antiangiogenic agents in neuroblastoma treatment protocols are scarce. This review adresses current knowledge on the important role and mechanisms of angiogenesis in neuroblastoma and summarizes available preclinical and clinical results of antiangiogenic agents used to treat neuroblastoma. Our review clearly demonstrates that clinical trials are urgently needed to bring forward promising antiangiogenesis concepts in neuroblastoma therapy.

Lymphangiogenesis and its regulation in human neuroblastoma

For the first time, we could detect lymph vessels in neuroblastoma (NB) by immunohistochemistry with the antibody D2_40. Furthermore, we demonstrate expression of the lymphangiogenic factors VEGF-C and VEGF-D and their receptors VEGFR-2 and VEGFR-3 in NB in vitro and in vivo by RT-PCR. However, addition of recombinant human VEGF-C or -D results in the absence of autocrine growth stimulus in NB cells. Treatment of NB cells with retinoic acid did not lead to a change in VEGF-C or VEGF-D mRNA expression. Incubation of the NB cells Lan-5 with 5-Aza-2'-deoxycytidine led to the up-regulation of VEGF-C mRNA expression, suggesting that the promotor of VEGF-C is methylated. Finally, VEGF-C mRNA expression could be effectively down-regulated by transfection with a specific siRNA in the NB cells Kelly. We conclude that lymphangiogenesis is involved in NB biology and that siRNA directed against VEGF-C may have a future role in anti-lymphangiogenic strategies in NB.

Changed times at Hematological Oncology

This editorial describes the changes to Hematological Oncology over the past 12 months and redefines the scope and the goals of the journal. As well as changes in format, an electronic manuscript submission system and a stringent peer-review policy (outlined here) have been implemented. The journal is a vehicle for high-quality articles in the broad field of experimental and clinical hematological oncology, and a medium for the publication of translational research. As well as submitted material, the journal solicits and publishes high-quality reviews from leading experts.