Neuroblastoma cell apoptosis induced by the synthetic retinoid N‐(4‐hydroxyphenyl)retinamide

Abstract

N-(4-hydroxyphenyl)retinamide (HPR) is a synthetic retinoid with anti-cancer properties and lower toxicity than all-trans retinoic acid (RA). Neuroblastoma cells treated with HPR and observed by fluorescence microscopy showed clear signs of apoptosis, such as chromatin condensation and margination, nuclear fragmentation and the presence of "apoptotic bodies". Moreover, measurements on a cell-by-cell basis by the flow-cytometric DNA-content in situ-terminal-deoxinucleotidyl-transferase(TDT) assay showed that apoptosis induced by HPR was dose- and time-dependent and that the fraction of apoptotic cells increased from approximately 15% at 1.25 microM at 2 days after treatment up to approximately 90% at 5 microM and 8 days of continuous treatment. Additionally, we found that cells were induced into apoptosis independently from the cell-cycle phase. In contrast, equimolar or higher doses of RA, from 5 microM to 80 microM, were able to inhibit growth by differentiation, but failed to induce apoptosis. We conclude that the functional effects of HPR and RA in LA-N-5 neuroblastoma cells are mediated by apoptosis and differentiation respectively, suggesting a potential clinical use of HPR in the management of neuroblastoma patients.

GADD153-mediated Anticancer Effects of N-(4-Hydroxyphenyl)retinamide on Human Hepatoma Cells

“…4 g of total RNAs from treated or untreated cells were reverse-transcribed with 200 units of SuperScript II RT enzyme (Invitrogen) in the presence of 1 mol/liter 1-base anchored oligo(dT) primers for 1 h at 42°C in a total volume of 10 l. The reaction was terminated by incubation at 75°C for 10 min. 2 l of the reaction mixture was PCR-amplified with Dynazyme (Finnzyme OY, Epsoo, Finland) in 1 mol/liter H-AP, a 13-mer (5Ј-end primers) and oligo(dT) 15 primers (3Ј-end primers), using a GeneAmp PCR system 9600 (PerkinElmer, Norwalk, CT). PCR reactions and reamplification of cDNAs of interest were carried out as previously described (34).…”

“…4HPR also induces apoptosis of human neuroblastoma cells (15,16), cervical (17), breast (18), human ovarian carcinoma cells (19), head and neck (20), lung (21), and human malignant hematopoietic cells. 4HPR-sensitive cells include those carrying mutations of the retinoic acid receptor (RAR) and which are thus unresponsive to all-trans-retinoic acid (22).…”

Recurrent Neuroblastoma

“…Unlike 13-cis-and all-trans-retinoic acids, fenretinide does not induce cellular differentiation, but induces apoptosis (Di Vinci et al, 1994). The mechanisms of action include de novo ceramide synthesis, generation of reactive oxygen species (Maurer et al, 1999), anti-angiogenesis (Ribatti et al, 2003), and increased natural-killer cell activity (Villa et al, 1993).…”

Cytochrome c Oxidase Subunit III

“…Additionally, 4HPR exhibits therapeutic effects as indicated by tumor regression in 4HPR-treated animals bearing carcinogen-induced or xenotransplanted human tumors (7). 4HPR also effectively induces apoptosis of human neuroblastoma cells (8,9), human ovarian carcinoma cells (10), and human malignant hematopoietic cell lines, and even cells carrying mutations of the retinoic acid receptor, which are thus unresponsive to all-trans-retinoic acid (11). Cell killing by 4HPR is antagonized by deregulated bcl-2 expression as well as by certain antioxidants (12).…”