Primitive neuroectodermal tumors/medulloblastoma

The aryl hydrocarbon receptor in the crossroad of signalling networks with therapeutic value

The aryl hydrocarbon receptor (AhR) is well-known for its major contributions to the cellular responses against environmental toxins and carcinogens. Notably, AhR has also emerged as a key transcription factor controlling many physiological processes including cell proliferation and apoptosis, differentiation, adhesion and migration, pluripotency and stemness. These novel functions have broadened our understanding of the signalling pathways and molecular intermediates interacting with AhR under both homeostatic and pathological conditions. Recent discoveries link AhR with the function of essential organs such as liver, skin and gonads, and with complex organismal structures including the immune and cardiovascular systems. The identification of potential endogenous ligands able to regulate AhR activity, opens the possibility of designing ad hoc molecules with pharmacological and/or therapeutic value to treat human diseases in which AhR may have a causal role. Integration of experimental data from in vitro and in vivo studies with "omic" analyses of human patients affected with cancer, immune diseases, inflammation or neurological disorders will likely contribute to validate the clinical relevance of AhR and the possible benefits of modulating its activity by pharmacologically-driven strategies. In this review, we will highlight signalling pathways involved in human diseases that could be targetable by AhR modulators and discuss the feasibility of using such molecules in therapy. The pros and cons of AhR-aimed approaches will be also mentioned.

Medulloblastoma cell invasion is inhibited by green tea (-)epigallocatechin-3-gallate

Epigallocatechin-3-gallate (EGCG), the major green tea polyphenol, can reach the brain following oral intake and could thus act as an anti-tumoral agent targeting several key steps of brain cancer cells invasive activity. Because integrin-mediated extracellular matrix recognition is crucial during the cell adhesion processes involved in carcinogenesis, we have investigated the effects of EGCG on different cellular integrins of the pediatric brain tumor-derived medulloblastoma cell line DAOY. Using flow cytometry, we report the levels of expression of several cell surface integrins in DAOY. These include high expression of alpha2, alpha3, and beta1 integrins, as well as alphav and beta3 integrins. Moreover, we provide evidence that EGCG can antagonize DAOY cell migration specifically on collagen by increasing cell adhesive ability through specific gene and protein upregulation of the beta1 integrin subunit. Our results suggest that this naturally occurring green tea polyphenol may thus be used as a nutraceutical therapeutic agent in targeting the invasive character of medulloblastomas.

Effects of basic fibroblastic growth factor on the growth of human medulloblastoma xenografts

The purpose of this study was to evaluate the effect of basic fibroblastic growth factor (bFGF) on the growth of human UM-MB1 medulloblastoma xenografts injected intracranially in nude mice. Under general anesthesia, a homogenous suspension of UM-MB1 cells (10(5)/10 microl) were injected in the caudoputamen nuclei of the right cerebral hemisphere using a stereotaxic apparatus. The treatment group (n = 9) received 10 microl of a bFGF solution (20 microg/ml) at 3 and 6 days following the inoculation of the cells at the injection site using the same stereotaxic coordinates. The control group (n = 9) were injected intracranially with a phosphate-buffered saline vehicle using a similar protocol. Mice were sacrificed 3 weeks following the xenograft surgery and the brains were prepared for histological observations as well as tumor volume evaluations. The mean volume of bFGF-treated tumors (mean volume +/- SD = 50.0 +/- 32.9 +/- mm3) was significantly smaller than for the non-treated xenografts (mean volume +/- SD = 199.0 +/- 42.1 mm3) (t-test, p < 0.001). Compared to non-treated tumor cells, bFGF-treated medulloblastoma cells had a greater cytoplasm volume and their nuclei contained more euchromatin suggesting that bFGF may initiate differentiation. In conclusion, our results suggest that bFGF may offer a new chemotherapeutic modality for the treatment of medulloblastoma.