Retinoic acid can combine with the nuclear retinoic acid receptor (RAR), leading to cell growth inhibition, as in certain tumors. Retinoic acid can also bind to the orphan nuclear receptor peroxisome proliferator-activated receptor beta/delta (PPAR beta/delta), resulting in stimulation of cell growth and inhibition of apoptosis. To bind to RAR, retinoic acid is carried into the nucleus by the c...

Vitamin A and its analogs (retinoids) have shown great prom ise for the chemoprevention of cancer as well as being a possible new class of chemotherapeutic agents. A Phase I and II trial of 13-c/s-retinoic acid in advanced cancers was initiated, and the clinical pharmacology of the drug was studied. All patients received p.o. 13-c/s-retinoic acid starting at 0.5 mg/ kg/day, escalating over 4 we...

The quantity of c-myc mRNA was measured during the retinoic-acid-induced differentiation of the pluripotent human teratoma cell line, Tera-2 cl. 13. As the cells were exposed to retinoic acid for longer periods of time the duration of the cell cycle progressively increased (measured by the rate of S phase entry) until the cells were effectively quiescent and expressed characteristic differentia...

Vitamin A and its analogues (retinoids) affect normal and malignant hematopoietic cells. We examined the effect of retinoids on the clonal growth in vitro of myeloid leukemia cells. Retinoic acid inhibited the clonal growth of the KG-1, acute myeloblastic leukemia, and the HL-60, acute promyelocytic leukemia, human cell lines. The KG-1 cells were extremely sensitive to retinoic acid, with 50% o...

Human plasma was analyzed by high performance liquid chromatography for the presence of retinoic acid and 4-oxoretinoic acid isomers. Peaks that coeluted with the reference compounds all-trans-retinoic acid, 13-cis-retinoic acid, and 13-cis-4-oxoretinoic acid were routinely observed in human plasma. These retinoids were unequivocally identified by the following methods: comigration with referen...

The effect of four different retinoids [retinol, 13-c/s-retinoic acid (Ro4-3780), /8-all-irans-retinoic acid, and aromatic retinoie acid ethyl ester (Ro10-9359)] on the cellular proliferation (cell number) and biochemical differentiation (tyrosinase activ ity) of a human melanoma cell line (MIRW) and three subclones was assessed. All four retinoids (10~6 M) inhibited the cellular proliferation ...

Chlorogenic acid (3-O-caffeoylquinic acid) inhibited haematin- and haemoglobin-catalysed retinoic acid 5,6-epoxidation. Some other phenol compounds (caffeic acid and 4-hydroxy-3-methoxybenzoic acid) also showed inhibitory effects on the haematin- and haemoglobin-catalysed epoxidation, but salicylic acid did not. Of the above compounds, caffeic acid and chlorogenic acid were potent inhibitors co...

The present study was designed to determine the effects of dietary 13c/s-retinoic acid and retinyl palmitate on mouse skin tumor promotion by 12-0-tetradecanoylphorbol-13-acetate (TPA). Female CD-I mice were initiated with 150 nmol of 7,12-dimethylbenz(a)anthracene and promoted twice weekly with 8 nmol of TPA. Diets supplemented with retinyl palmitate to yield 60,000 or 200,000 IU or 700,000 fo...

Mutations in the APC (adenomatous polyposis coli) tumor suppressor gene cause uncontrolled proliferation and impaired differentiation of intestinal epithelial cells. Recent studies indicate that human colon adenomas and carcinomas lack retinol dehydrogenases (RDHs) and that APC regulates the expression of human RDHL. These data suggest a model wherein APC controls enterocyte differentiation by ...

The electrical activity of neurons is known to play a role in neuronal development, as well as repair of adult nervous tissue. For example, the extension of neurites and motility of growth cones can be modulated by changes in the electrical firing of neurons. The vitamin A metabolite retinoic acid also plays a critical role during nervous system development and is also known to elicit regenerat...