RESUMO
Glioblastoma (GBM) is a highly aggressive primary brain tumor with a poor prognosis. Treatment with temozolomide, standard of care for gliomas, usually results in drug resistance and tumor recurrence. Therefore, there is a great need for drugs that target GBM. NEO214 was generated by covalently linking rolipram to perillyl alcohol (POH) via a carbamate bond to form the rolipram-perillyl alcohol conjugate. We show here that NEO214 is effective against both temozolomide-sensitive and temozolomide-resistant glioma cells. Furthermore, NEO214 is effective for different mechanisms of temozolomide resistance: overexpression of MGMT (O6-methylguanine methyl-transferase); deficiency in specific mismatch repair proteins; and overexpression of base excision repair (BER) proteins. NEO214-induced cytotoxicity involves apoptosis triggered by endoplasmic reticulum (ER) stress, as well as activating the Death Receptor 5 (DR5)/TNF-related apoptosis-inducing ligand (TRAIL/Apo2L) pathway. In vitro studies show that glioma cells treated with NEO214 express DR5 and exhibit cell death in the presence of recombinant TRAIL, a growth factor constitutively produced by astrocytes. Our in vitro 3D coculture data show that induction of DR5 in glioma cells with NEO214 and TRAIL cause tumor cell death very effectively and specifically for glioma cells. In vivo studies show that NEO214 has antitumor efficacy in orthotropic syngeneic rodent tumor models. Furthermore, NEO214 has therapeutic potential especially for brain tumors because this drug can cross the blood-brain barrier (BBB), and is effective in the TRAIL-rich astrocyte microenvironment. NEO214 is a strong candidate for use in the treatment of GBMs.
Assuntos
Glioblastoma/tratamento farmacológico , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/genética , Rolipram/farmacologia , Ligante Indutor de Apoptose Relacionado a TNF/genética , Animais , Apoptose/efeitos dos fármacos , Astrócitos/efeitos dos fármacos , Barreira Hematoencefálica/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Camundongos , Monoterpenos/química , Monoterpenos/farmacologia , Rolipram/química , Transdução de Sinais/efeitos dos fármacos , Temozolomida/farmacologia , Microambiente Tumoral/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
As the endothelial-to-mesenchymal transition (EndMT) supports the pro-angiogenic and invasive characteristics of glioblastoma multiforme (GBM), blocking this process would be a promising approach to inhibit tumor progression and recurrence. Here, we demonstrate that glioma stem cells (GSC) induce EndMT in brain endothelial cells (BEC). TGF-ß signaling is necessary, but not sufficient to induce this EndMT process. Cell-to-cell contact and the contribution of Notch signaling are also required. NEO212, a conjugate of temozolomide and perillyl alcohol, blocks EndMT induction and reverts the mesenchymal phenotype of tumor-associated BEC (TuBEC) by blocking TGF-ß and Notch pathways. Consequently, NEO212 reduces the invasiveness and pro-angiogenic properties associated with TuBEC, without affecting control BEC. Intracranial co-implantation of BEC and GSC in athymic mice showed that EndMT occurs in vivo, and can be blocked by NEO212, supporting the potential clinical value of NEO212 for the treatment of GBM.
