Human neuroblastoma cells and 13-cis-retinoic acid

Summary To a limited extent, we corroborated a previous report of human neuroblastoma sensitivity to 13-cis-retinoic acid. Seven cultured human neuroblastoma, two primitive neuroectodermal tumor, and one melanoma cell line were exposed to 0.001 to 10.0 º M 13-cis-retinoic acid for six to fourteen days. The neuroblastoma cell line, SK-N-DZ, was the only cell line lysed by all concentrations of 13-cis-retinoic acid. The other cell lines were refractory to concentrations as high as 10 µM. Increased cell process formation was observed in three neuroblastoma, SK-N-SH, SK-N-BE, SK-N-LE, and one melanoma cell line. We conclude that sensitivity to 13-cis-retinoic acid is unevenly distributed among histogenetically similar tumors from different patients.     

Structure-activity relationships of retinoids in hamster tracheal organ culture

Structure-activity relationships are summarized for 87 retinoids, using reversal of keratinization in the hamster tracheal organ culture system to measure biological activity. Classes of compounds evaluated include all-trans-retinoic acid and its esters, ring-modified analogs of all-trans-retinoic acid and its esters, side-chain-modified analogs of all-trans-retinoic acid and its esters, analogs in which both ring and side chain have been modified, all-trans-retinol and derivatives, all-trans-retinyl amine derivatives, all-trans-retinal derivatives, all-trans-retinoic acid amides, 13-cis-retinoic acid and derivatives, and 5,6-epoxyretinoids. the activity of many synthetic amide derivatives of all-trans- or 13-cis-retinoic acid approaches that of the parent compounds. No metabolite of all-trans- or 13-cis-retinoic acid has yet been identified which has greater activity than the parent compounds in this assay. New synthetic derivatives with a gem-dimethyl group at position 4 in the cyclohexenyl ring and two aromatic rings in the side chain have activity equal to or greater than that of all-trans- or 13-cis-retinoic acid, with some activity detectable in the 10(-11) M range.     

Effect of delay in administration of 13-cis-retinoic acid on the inhibition of urinary bladder carcinogenesis in the rat.

The effect of a delay in starting 13-cis-retinoic acid treatment on the inhibition of urinary bladder carcinoma induced by N-butyl-N-(4-hydroxybutyl)nitrosamine was studied in male Fischer 344 rats. Animals received a total p.o. dose of either 1200, 1800 or 2400 mg N-butyl-N-(4-hydroxybutyl)nitrosamine over a period of six weeks. At either one, five, and nine weeks after the last N-butyl-N-(4-hydroxybutyl)nitrosamine intubation, animals were started on a diet supplemented with 13-cis-retinoic acid (240 mg/kg of laboratory chow) or continued on laboratory chow. Animals were killed at one year after the first carcinogen intubation for histological evaluation of the bladder. Feeding of 13-cis-retinoic acid reduced the incidence, average number, and severity of transitional cell carcinomas as well as hyperplasia and cellular atypia. Furthermore, even a nine-week delay in starting the retinoid feeding did not diminish the ability of 13-cis-retinoic acid to inhibit bladder carcinogenesis.     

Effects of dietary retinyl palmitate or 13-cis-retinoic acid on the promotion of tumors in mouse skin

The present study was designed to determine the effects of dietary 13-cis-retinoic acid and retinyl palmitate on mouse skin tumor promotion by 12-O-tetradecanoylphorbol-13-acetate (TPA). Female CD-1 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 for 5 wk followed by 350,000 IU per kg of diet (700,000/350,000) fed to mice during tumor promotion resulted in 9%, 37%, and 65% inhibition of the papilloma yield, respectively, at 21 wk of promotion. Although topical applications of 13-cis-retinoic acid have been almost as effective as retinoic acid in preventing the appearance of mouse skin tumors, dietary 13-cis-retinoic acid at 200,000 or 700,000 IU per kg of diet resulted in no reduction in papilloma yield but did result in a dose-dependent decrease in the tumor burden (weight of tumors per mouse). Therefore, dietary retinyl palmitate yielded a dose-dependent inhibition of the number and weight of tumors promoted by TPA, whereas dietary 13-cis-retinoic acid resulted in a decrease in weight but not in number of tumors promoted by TPA.     

Comparative activity of dietary or topical exposure to three retinoids in the promotion of skin tumor induction in mice

The activity of dietary and topical administration of three retinoids, all-trans-retinoic acid, 13-cis-retinoic acid, and N-(4-hydroxyphenyl)retinamide (4-HPR), as promoters of skin tumor induction in SENCAR mice was studied. When administered as dietary supplements at their maximum tolerated dose levels, all three retinoids promoted tumorigenesis in mice initiated with a single topical dose of 5 micrograms 7,12-dimethylbenz(a)anthracene. Maximal promoting activity was observed with dietary 13-cis-retinoic acid; dietary 4-HPR was significantly less active than was either isomer of retinoic acid. When administered via topical application, all-trans- and 13-cis-retinoic acids both promoted skin tumor induction; 4-HPR did not. HPLC analysis of skin samples from mice receiving dietary 4-HPR showed the parent compound and six metabolites; these metabolites were not found in the skin of mice receiving topical 4-HPR exposure, although 4-HPR itself was present. These data indicate that skin tumor promotion can be induced by systemic administration as well as topical application of the all-trans- and 13-cis-retinoic acids. Substitution of a 4-hydroxyphenylamide terminal group results in a significant reduction in promoting activity. 4-HPR appears to require metabolic activation for tumor promoting activity; this metabolism does not occur in the skin following topical application, but is observed following systemic exposure.     

13-cis-retinoic acid and cancer chemoprevention.

Chemoprevention is the newest strategy for controlling and managing cancer. At present, the multistep character of epithelial carcinogenesis makes this disease process the most amendable to chemopreventive interventions, which occur in the postinitiation, preinvasive phases. Chemoprevention study has focused on oral carcinogenesis because of its excellent preclinical models, well-defined premalignant phase (leukoplakia), ease of monitoring, and link through field carcinogenesis to other epithelial carcinogeneses of the upper and lower aerodigestive tract. Retinoids, the derivatives of vitamin A, are the most-studied chemopreventive agents, and 13-cis-retinoic acid is the best-studied chemopreventive retinoid. Laboratory study of the newly discovered nuclear receptors of retinoic acid is closing in on the precise mechanism of retinoid action. Only 13-cis-retinoic acid, at high doses, has established chemopreventive activity, which is in suppressing oral premalignancy and preventing second primary head-and-neck tumors. Preclinical and clinical work in the other aerodigestive sites of the lung and esophagus are at an early phase of study with no conclusive results currently available. High-dose 13-cis-retinoic acid also has achieved significant activity in preventing invasive carcinomas of the skin. High-dose 13-cis-retinoic acid, however, is not ideal for widespread chemoprevention approaches because of its toxicity. The toxicity-to-risk balance is delicate and complicated.(ABSTRACT TRUNCATED AT 250 WORDS)     

The role of 13 cis-retinoic acid in the remission induction of a patient with acute promyelocytic leukemia

The addition of retinoic acid to human promyelocytic leukemia cells in culture results in their differentiation to mature myeloid forms with acquisition of the differentiated phenotype, i.e., the ability to reduce nitroblue tetrazolium. A heavily pretreated patient with acute promyelocytic leukemia and residual malignant cells in his marrow after multiple courses of chemotherapy was given 13-cis-retinoic acid upon demonstration of both morphologic and functional differentiation of his leukemic cells by transretinoic acid in vitro. The patient achieved a complete remission and was maintained on 13-cis-retinoic acid for 1 year, when the patient relapsed with a population of cells that were resistant to retinoic acid-induced differentiation.     

An International Evaluation of the Cancer-Preventive Potential of Nine Retinoids

The International Agency for Research on Cancer (IARC) convened a working Group of experts in March 1999 to ‍evaluate the cancer preventive potential of nine retinoids and to compile the fourth volume of the IARC Handbooks ‍of Cancer Prevention. The handbook provides a comprehensive review of the relevant information in the published ‍scientific literature through March 1999 on the potential role of all-trans-retinoic acid, 13-cis-retinoic acid, 9-cisretinoic ‍acid, all-trans N-(4-hydroxyphenyl)retinamide, etretinate, acitretin, N-ethylretinamide, targretin and LGD ‍1550 in cancer prevention. Of these, the data suggest that all-trans-retinoic acid, 13-cis-retinoic acid and Nethylretinamide ‍are not suitable for chemoprevention of cancer in humans either because they are too toxic, may ‍enhance cancer occurrence or are ineffective. In contrast, 9-cis-retinoic acid, etretinate and acitretin show some ‍promise, but more data are required, while all- trans N-(4-hydroxyphenyl)retinamide is quite promising. Targretin ‍and LGD 1550 are of interest, based on theoretical grounds, but there are no significant human and little experimental ‍data as yet.     

Effects of 13-cis retinoic acid on dibutyl-nitrosamine-induced cell kinetic changes in mouse urinary bladder epithelium

The effect of 13-cis-retinoic acid on cell proliferation in normal urothelium and during early stages in N-nitrosodibutylamine (DBN) induced malignant transformation was studied in male hairless mice. The retinoic acid was administered orally, and the parameters studied were (a) variations in total cell number, (b) labelling index (LI), (c) mitotic rate (MR), (d) the proportions of DNA-synthesizing cells in the diploid and tetraploid fractions, and (e) morphological changes. 13-cis-retinoic acid caused no effect on these parameters in normal urothelium, nor did it prevent the changes caused by DBN in the urothelium prior to malignant development.     

Synergistic effects of new chemopreventive agents and conventional cytotoxic agents against human lung cancer cell lines

Non-small cell lung cancer (NSCLC) cells have constitutively high expression of cytosolic phospholipase A2 (cPLA2) and cyclooxygenase (COX) 2. These NSCLC cells also have increased prostaglandin expression (PGE2). Many lung cancers also express 12-lipoxygenase RNA and 12-lipoxygenase protein and biosynthesize 12(S)-hydroxyeicosatetraenoic acid, which correlates with their metastatic potential. Several studies have demonstrated that COX-1 and COX-2 inhibitors could inhibit the in vitro growth of human lung cancer cell lines. In this report, we evaluated the growth-inhibitory effects of sulindac sulfide, a COX-1 and COX-2 inhibitor; exisulind (sulindac sulfone), a novel proapoptotic agent that does not inhibit COX enzymes; and nordihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor on human lung cancer cell lines. We compared these effects with those of 13-cis-retinoic acid, a chemoprevention agent, and with the cytotoxic chemotherapeutic agents paclitaxel and cisplatin, alone or in combination. Our goal was to develop new chemoprevention and treatment strategies. Each of the six agents tested inhibited the in vitro growth of three NSCLC and three SCLC cell lines at the highest concentration. Paclitaxel was the most potent agent (IC50 = 0.003-0.150 microM); sulindac sulfide, NDGA, and 13-cis-retinoic acid had intermediate potency (IC50 = 4-80 microM), and cisplatin and exisulind were the least potent (IC50 = 150-500 microM). Combination studies showed synergistic interactions for sulindac sulfide, exisulind, and NDGA with paclitaxel, cisplatin, and 13-cis-retinoic acid, regardless of drug-resistance phenotype. At high concentrations, the combination of 13-cis-retinoic acid and each of the five other drugs resulted in a strong synergistic effect. These studies provide a rationale for chemoprevention (exisulind +/- retinoic acid +/- NDGA) and therapeutic (exisulind +/- paclitaxel +/- cisplatin) studies in patients at risk for, or with, lung cancer.     

13-cis-retinoic acid induces cellular differentiation and durable remission in refractory cutaneous Ki-1 lymphoma

A 35-year-old man with refractory cutaneous Ki-1 lymphoma was salvaged successfully with oral 13-cis-retinoic acid (1 mg/kg/day). He had a complete remission lasting for 20 months before a single nodule recurred on his skin. Excisional biopsy of the recurrent tumor revealed a distinct morphologic change, suggesting cellular differentiation toward a more benign phenotype. No significant side effects were noted except mild xerostomia, bone pain, and hyperlipidemia. The authors believe that 13-cis-retinoic acid should be considered in the treatment of cutaneous Ki-1 lymphoma.     

Influence of the duration of topical 13-cis-retinoic acid treatment on inhibition of mouse skin tumor promotion

The effect of the time and duration of retinoid treatment on the inhibition of Stage II tumor promotion by 12-O-tetradecanoylphorbol-13-acetate (TPA) was studied in CD-1 mice. All mice were initiated with 400 nmol of benzo(a)pyrene and received Stage I tumor promotion (3.2 nmol of TPA twice weekly for 2 wk). Animals were then randomized into groups which received 13-cis-retinoic acid during early, middle, or late Stage II promotion. 13-cis-Retinoic acid pretreatments starting on Day 1, Wk 8, or Wk 23 of Stage II promotion resulted in 47, 28, or 19% inhibition, respectively, of TPA-induced tumor formation. One-half of the mice receiving 13-cis-retinoic acid at Day 1 or Wk 8 were removed from the retinoid treatments at Wk 23, the time of cessation of TPA promotion. The inhibition of tumor formation remained constant during the 15-wk observation period after cessation of retinoid treatment, suggesting that retinoid inhibition of mouse skin tumor promotion is stable in the absence of further promotion and preceded the step of irreversible conversion of promoter dependence to promoter independence.     

Effect of long-term administration of retinoids on rats exposed transplacentally to ethylnitrosourea

A neurogenic cancer model, involving transplacental administration of ethylnitrosourea (ENU) to Sprague-Dawley rats, was employed to evaluate the efficacy of retinyl acetate, 13-cis-retinoic acid, and all-trans-retinoic acid in prevention of nervous system tumors in the offspring. Supplementation of the diet with either of these retinoids did not alter the incidence, number, or latency period of the induced neurogenic tumors. Long-term administration of high doses of 13-cis-retinoic acid (240 mg/kg of diet) or all-trans-retinoic acid (65 mg/kg of diet) produced lethal toxicity in this strain of rats, possibly due to interference with vitamin K absorption and the resulting internal hemorrhages associated with hypoprothrombinemia. Prolonged feeding of retinyl acetate increased the retinyl palmitate level in the liver. The concentration reached was not dose-dependent; a maximum level (approximately 10-fold that of controls) was observed after six months of feeding. An unexpected observation was the decrease in liver retinyl palmitate concentration in the livers of rats fed 13-cis-or all-transretinoic acid.     

13-cis-Retinoic acid does not increase the true remission rate and the duration of true remission (induced by cytotoxic chemotherapy) in patients with chronic phase chronic myelogenous leukemia

Treatment of chronic phase chronic myelogenous leukemia with hydroxyurea or busulfan rarely induces cytogenetic (true) remissions. Intensive chemotherapy induces brief true remissions in approximately 50% of patients. We added 13-cis-retinoic acid to daunorubicin, cytosine arabinoside, and thioguanine to determine if it could increase the incidence and duration of remission induced by cytotoxic chemotherapy. Of the 17 evaluable patients, one patient (6%) achieved complete remission, and seven patients (41%) achieved partial remissions. The median duration of remission was 1.6 months. We conclude that 13-cis-retinoic acid does not increase the incidence and duration of remission in chronic phase chronic myelogenous leukemia.     

Retinoids cause apoptosis in pancreatic cancer cells via activation of RAR-gamma and altered expression of Bcl-2/Bax

All-trans-retinoic acid and 9-cis-retinoic acid have been reported to have inhibitory effects on pancreatic adenocarcinoma cells and we have shown that this is partly due to induction of apoptosis. In this study, the mechanisms whereby 9-cis-retinoic acid induces apoptosis in these cells were investigated. An involvement of the Bcl-2 family of proteins was shown, such that 9-cis-retinoic acid causes a decrease in the Bcl-2/Bax ratio. Overexpression of Bcl-2 also resulted in inhibition of apoptosis induced by 9-cis-retinoic acid. Furthermore, two broad-range caspase inhibitors blocked DNA fragmentation induced by 9-cis-retinoic acid, but had no effect on viability defined by mitochondrial activity. Using synthetic retinoids, which bind selectively to specific retinoic acid receptor subtypes, we further established that activation of retinoic acid receptor-gamma is essential for induction of apoptosis. Only pan-retinoic acid receptor and retinoic acid receptor-gamma selective agonists reduced viability and a cell line expressing very low levels of retinoic acid receptor-gamma is resistant to the effects of 9-cis-retinoic acid. A retinoic acid receptor-beta/gamma selective antagonist also suppressed the cytotoxic effects of 9-cis-retinoic acid in a dose-dependent manner. This study provides important insight into the mechanisms involved in suppression of pancreatic tumour cell growth by retinoids. Our results encourage further work evaluating the clinical use of receptor subtype selective retinoids in pancreatic carcinoma.     

Influence of 13-cis-retinoic acid on mouse skin tumor initiation and promotion

Tumor initiation in CD-1 mice by benzo[a]pyrene (BaP) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was unaffected by topical pretreatment with 13-cis-retinoic acid (13-cis-RA). Likewise, anthralin-induced tumor promotion in SENCAR mice was unaffected by pretreatment with 13-cis-RA. These results suggest that the action of retinoids in preventing either tumor initiation or promotion is very carcinogen or cocarcinogen specific.     

Acne, retinoids, and dermabrasion

A group of nine patients with severe nodulocystic acne vulgaris were treated with oral 13-cis-retinoic acid and their acne cleared. During or after retinoid therapy, all patients underwent full-face dermabrasion. Postoperative healing was normal, and no significant complications were seen.     

Dissecting folliculitis of the scalp. A case report of combined treatment using tissue expansion, radical excision, and isotretinoin.

Dissecting folliculitis of the scalp can develop into an extensive, hypertrophic scarred lesion that is unresponsive to routine treatment. In these situations, radical excision of the affected area and concurrent perioperative treatment with isotretinoin (13-cis-retinoic acid) may be effective. The authors describe a case, illustrating the successful clinical application of this technique.     

Pharmacokinetics and effects on plasma retinol concentrations of 13-cis-retinoic acid in melanoma patients.

The pharmacokinetics of 13-cis-retinoic acid (13cisRA) and its effects on retinol plasma levels were investigated after the first and the last doses in melanoma patients, who participated in a study run to assess tolerance over a long period of a treatment schedule of 13cisRA associated with recombinant interferon alpha2a (rIFN-alpha2a). Melanoma patients with regional node metastases after radical surgery were randomized to be treated for 3 months with rIFN-alpha2a, 3 x 10(6) IU s.c. every other day, associated with oral 13cisRA at doses of 20 mg day(-1) (five patients) or 40 mg every other day (seven patients). Maximum 13cisRA blood concentrations usually occurred 4 h after drug administration, with average values of 406 and 633 ng ml(-1) (i.e. 1.3 and 2.1 microM) after the 20 and 40 mg dose respectively. The average half-life (t(1/2)) was approximately 30 h. The maximum concentration, the t(1/2) and the area under the concentration-time curves from 0 to 48 h (AUC(0-48)) of 13cisRA did not change after multiple dosing, whereas the AUC(0-48) of its major blood metabolite, 4-oxo-13-cis-retinoic acid, increased. Immediately after 13cisRA treatment, retinol plasma levels started to decline and they reached the lowest values (approximately 20% reduction) shortly after the time of maximum 13cisRA concentrations (i.e. 4-12 h after drug intake). Afterwards, values returned to baseline. The amount of retinol reduction in time was correlated with 13cisRA maximum concentrations.     

Effects of retinoids on in vitro differentiation of bone marrow cells in the myelodysplastic syndrome

The effect of retinoids on cell differentiation in the myelodysplastic syndrome was studied in short-term liquid cultures of bone marrow from 13 patients. After incubation with 13-cis-retinoic acid there was a significant decrease in the percentages of promyelocytes and in Leu-M3-binding cells. Lue-M3 is mainly a monocyte marker, and retinoids thus seem to induce a shift from monocytoid to myeloid differentiation. Patients with refractory anemia with an excess of blasts responded the most, and did also show a significant decrease in OKIa1-binding cells. Etretinate, on the other hand, did not show any differentiation-inducing activity. The results support earlier reports that retinoic acid might be useful in the treatment of the myelodysplastic syndrome. Whether this in vitro technique offers a possibility to predict the clinical outcome remains to be shown.