alitretinoin and Glioma

In this article we report the results of a study of the relationship between response and progression in 375 patients with recurrent glioma enrolled in phase II chemotherapy trials. We reviewed the records of patients from 8 consecutive phase II trials, including 225 patients with recurrent glioblastoma multiforme and 150 with recurrent anaplastic astrocytoma. Median age was 45 years (range, 15-82) and median Karnofsky performance score was 80 (range, 60-100). Forty-one patients (11%) had more than two prior resections and/or more than two prior chemotherapy regimens. Best response was complete (n = 1) or partial (n = 33) in 34 patients (9%). Median time to response was 14 weeks, and median response duration was 44 weeks. Simon-Makuch estimates for 52-week progression-free survival for patients progression-free at 13 weeks were 48% for response and 28% for nonresponse. When response was treated as a time-dependent covariate in a Cox proportional hazards regression analysis, response was associated with significantly lower failure rates (hazard ratio 0.5; 95% confidence interval 0.3-0.8; P = 0.0016). This study showed that response in recurrent glioma is associated with a significant reduction in progression rates.

Topics: Actuarial Analysis; Adolescent; Adult; Aged; Aged, 80 and over; Alitretinoin; Antineoplastic Combined Chemotherapy Protocols; Astrocytoma; Brain Neoplasms; Carboplatin; Combined Modality Therapy; Disease Progression; Disease-Free Survival; Eflornithine; Female; Fluorouracil; Glioblastoma; Glioma; Humans; Interferon-beta; Male; Menogaril; Middle Aged; Neoplasm Recurrence, Local; Procarbazine; Prognosis; Proportional Hazards Models; Texas; Treatment Outcome; Tretinoin

N-(4-hydroxyphenyl)retinamide (4-HPR), a synthetic retinoid is under clinical evaluation as a therapeutic agent in a variety of cancers. Its mechanism(s) of action involves multiple overlapping pathways that still remain unclear. In glioma cells its mechanism of action is not well elucidated. Here, we show that 4-HPR and not all-trans retinoic acid and 9-cis retinoic acid effectively induce apoptosis in glioma cells. 4-HPR-induced apoptosis is associated with hydroperoxide production and loss of mitochondrial membrane potential (Delta Psi(m)). Ultrastructural changes further indicate 4-HPR-induced mitochondrial swelling, endoplasmic reticulum (ER) dilation as well as close proximity of mitochondria and ER. As suggested by dilated ER, 4-HPR treatment increased the free cytosolic Ca(2+) as well as mitochondrial Ca(2+). Chelation of extracellular Ca(2+) by EGTA did not prevent Ca(2+) elevation, thus suggesting involvement of intracellular calcium stores in the release. Buffering of intracellular calcium by BAPTA-AM did not prevent 4-HPR-induced apoptosis; however, blocking the release of Ca(2+) from ER by heparin inhibited apoptosis, indicating the role of depletion of Ca(2+) from ER stores in apoptosis. 4-HPR treatment also resulted in an increase in Bax levels along with its translocation to mitochondria that promote mitochondrial membrane permeabilization. 4-HPR-induced apoptosis was further associated with the release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria to cytosol and nucleus, respectively, along with caspase-3 and caspase-7 activation. However, AIF nuclear translocation, peripheral chromatin condensation and apoptosis were not completely prevented by general caspase inhibitors, thus suggesting involvement of a caspase-dependent and caspase-independent pathway in 4-HPR-induced apoptosis. Taken together, these results suggest the role of mitochondrial-mediated pathway and ER stress as a key event in 4-HPR-induced apoptosis in glioma cells.

Topics: Alitretinoin; Animals; Antineoplastic Agents; Apoptosis; Apoptosis Inducing Factor; Calcium; Cell Line, Tumor; Cytochromes c; Endoplasmic Reticulum; Fenretinide; Glioma; Humans; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Rats; Reactive Oxygen Species; Receptors, Retinoic Acid; Retinoic Acid Receptor gamma; Retinoid X Receptor alpha; Tretinoin