title: Elevated plasma lipid peroxide content correlates with rapid plasma clearance of all-trans-retinoic acid in patients with advanced cancer.
abstract: The addition of lipid hydroperoxides greatly accelerates the rate of oxidative catabolism of all-trans-retinoic acid (RA) in human cell microsomes; hydroperoxy metabolites of the arachidonate cascade are particularly active in the microsomal system. We have measured the plasma content of lipid peroxides in cancer patients during the course of therapy with RA, seeking to assess whether a correlation exists between the rate of oxidative catabolism of exogenously administered RA and whole body lipid peroxide levels. The assay used for plasma lipid peroxides is the capacity to react with thiobarbituric acid under specified conditions; the result is expressed as TBARS (thiobarbituric acid reactive substances). RA administration produced its own accelerated clearance RA within 72 h. Patients were considered to have "normal" or "rapid" baseline catabolism of RA if their Day 1 area under RA concentration over time curve was greater or less than 300 ng.h/ml, respectively. The mean plasma TBARS levels were: 12 normal volunteers = 0.14 microM; 19 "normal" RA catabolizers = 0.25 microM; and 14 "rapid" catabolizers = 0.82 microM. P = 0.008 (rapid catabolizers versus normal volunteers) and 0.05 (rapid catabolizers versus normal catabolizers). Repeat TBARS determinations were made during the course of therapy in 17 patients, all of whom converted to "rapid" RA catabolism on therapy. An increase in plasma TBARS levels > or = 20% of baseline was observed in 5 of 5 prostate cancer patients and 8 of 12 lung cancer patients treated with continuous RA therapy for 2 and 4 weeks, respectively. These observations support the hypothesis that high levels of lipid peroxides and rapid oxidative catabolism of RA are positively correlated.
authors.affiliation: Developmental Chemotherapy Service, Memorial Sloan Kettering Cancer Center, New York, New York 10021.
authors.forename: J F
authors.initials: JF
authors.lastname: Muindi
authors.forename: H I
authors.initials: HI
authors.lastname: Scher
authors.forename: J R
authors.initials: JR
authors.lastname: Rigas
authors.forename: R P
authors.initials: RP
authors.lastname: Warrell
authors.forename: C W
authors.initials: CW
authors.lastname: Young
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000097:blood / Q000188:drug therapy; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000097:blood / Q000188:drug therapy; D008054:Lipid Peroxides / Q000097:blood* / Q000378:metabolism; D008175:Lung Neoplasms / Q000097:blood / Q000188:drug therapy; D008297:Male; D008657:Metabolic Clearance Rate; D009101:Multiple Myeloma / Q000097:blood / Q000188:drug therapy; D009369:Neoplasms / Q000097:blood* / Q000188:drug therapy*; D011471:Prostatic Neoplasms / Q000097:blood / Q000188:drug therapy; D012016:Reference Values; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D014212:Tretinoin / Q000097:blood* / Q000627:therapeutic use
chemical_list: D008054:Lipid Peroxides; D017392:Thiobarbituric Acid Reactive Substances; D014212:Tretinoin