Synthetic retinoid CD437 induces S-phase arrest and apoptosis in human prostate cancer cells LNCaP and PC-3

BACKGROUND: Exposure of prostate carcinoma cell lines to retinoids, which function through the classical retinoic acid nuclear receptor, (RARs) or retinoid X receptors (RXRs), results in minimal cytostatic inhibition of cell proliferation. METHODS: Growth inhibition and various regulatory responses were investigated in two human prostate carcinoma cell lines (LNCaP and PC-3) treated with or without a synthetic retinoid, CD 437. RESULTS: Incubation of prostate carcinoma cell lines with a novel retinoid CD437 resulted in the marked inhibition of proliferation. LNCaP and PC-3 possessed IC50 values for CD437 of 375 nM and 550 nM, respectively. Incubation with 1 microM CD437 for 24 hr resulted in 100% and 60% inhibition of growth in LNCaP and PC-3 cells, respectively. Simultaneously, cell flow cytometric analyses revealed a dramatic increase of the cell population in S phase, in both LNCaP (from 38.6% up to 86.7%) and PC-3 (27.9% to 55.7%), and a decreased proportion of cells in G2 phase, in LNCaP (from 23.7% down to 1.2%) and PC-3 (14.9% to 2.2%), indicating a significant S-phase arrest. The cell growth inhibition and S-phase arrest in these cells were followed by apoptosis, as revealed by the acquisition of the characteristic cell morphology including the appearance of apoptotic bodies, and further confirmed by cellular DNA fragmentation. CD437-induced-S phase arrest was associated with upregulated mRNA levels of p21waf1/cip1/sdi1 in both LNCaP (p53+/+) and PC-3 (53-/-) cells. CONCLUSIONS: CD437 represents a unique retinoid that induces S-phase arrest and apoptosis in both androgen-dependent (LNCaP) and -independent (PC-3) human prostate cancer cells, suggesting a potential role of CD437 in the treatment of human prostate cancer.     

Implication of p53 in growth arrest and apoptosis induced by the synthetic retinoid CD437 in human lung cancer cells.

CD437 is a novel retinoid that can induce apoptosis in a variety of tumor cell types by an unknown mechanism. We found that CD437 up-regulated the expression of p21(WAF1/CIP1), Bax, and Killer/DR5 and induced G1 arrest and rapid apoptosis in three human non-small cell lung carcinoma cell lines with wild-type p53 but not in five cell lines with mutant p53, suggesting a role for p53 in the effects of CD437. Using H460 cells in which wild-type p53 protein was degraded by transfection of the human papillomavirus 16 E6 (HPV-16 E6) gene and H460 cells transfected with a control plasmid only, we found that CD437 increased p53, p21(WAF1/CIP1), Bax, and Killer/DR5 in the control transfectants. In contrast, the constitutive p53 protein level was suppressed, and the ability of CD437 to increase p53 and its downstream genes was compromised in E6 transfectants. In addition, CD437 induced G1 arrest and apoptosis in the control transfectants but not in the E6-transfected cells. These results indicate that p53 plays a role in CD437-induced growth inhibition and apoptosis in human non-small cell lung carcinoma cells.     

In vitro andin vivo antiinflammatory activities of C10 substituted anthralin derivatives

Conclusions In model systems where anthralin and butanthrone have a high anti-proliferative activity, e.g., inhibition of keratinocyte metabolism in culture or inhibition of ornithine decarboxylase inductionin vivo, CD 003 is inactive. However, in the skin disease psoriasis there is both an inflammatory as well as a differentiation/proliferation component, and consequently we have evaluated anthralin and butanthrone for their potentialin vivo antiinflammatory activities. In addition, we have compared a new analogue, substituted at C₁₀, with these two compound. Our results support the belief that modification of the anthralin structure can result in the formation of less toxic, less irritant and less staining analogues, which maintain or significantly improve upon the topical antiinflammatory properties of anthralin. The possibility that such analogues will be of use in the treatment of skin diseases with a major inflammatory component is at present being investigated.     

Reappraising the phototoxicity of tretinoin: a report of four controlled clinical trials

Background: Retinoids are photoreactive molecules found in skin and retinal tissue. The use of retinoids in pharmacologic doses, applied topically, raises the potential of phototoxicities. Recent review articles and current US drug labeling indicate that tretinoin is a phototoxin. In developing a new formulation of topical all- trans -retinoic acid (tretinoin), formal testing of dermal photoreactions was therefore undertaken.
Methods: Four prospective, randomized, and controlled trials were carried out in healthy volunteers at two independent research facilities. Two trials examined phototoxicity following 24 h of drug exposure under occlusion (combined n =51), and two examined photoallergenicity following a 3-week, six dose induction phase (combined n =72) followed by challenge.
Results: No phototoxic or photoallergic reactions occurred with tretinoin 0.05% in a new gel formulation.
Conclusion: The findings in these studies are consistent with previous studies of tretinoin in various formulations, and support the conclusion that tretinoin appears to be neither phototoxic nor photoallergenic in vivo .     

Modulation of cellular cholesterol and its effect on cornified envelope formation in cultured human epidermal keratinocytes.

When cultured human epidermal keratinocytes (NHK) reach confluence they start to differentiate and an increase in the total cellular cholesterol content is observed. This increase parallels the appearance of a characteristic feature of terminal keratinocyte differentiation, the spontaneous formation of cornified envelopes (CE). Synthesis of CE is catalyzed by the plasma membrane-associated transglutaminase (TGm). Supplementation of the medium with inhibitors of cholesterologenesis suppressed increase in cholesterol levels and CE formation but did not interfere with TGm expression or TGm activity. Modulation of the plasma membrane cholesterol-phospholipid ratio of confluent NHK cultures using either pure phospholipid liposomes or liposomes enriched in cholesterol strongly affected spontaneous CE formation. Pure phospholipid liposomes completely inhibited CE formation, whereas cholesterol-enriched liposomes ensured envelope formation, even in the presence of inhibitors of cholesterol synthesis. From these results we conclude that in differentiating NHK an increase in the cellular cholesterol level is part of the differentiation program and is essential for the spontaneous CE formation.     

Glucocorticoids: binding affinity and lipophilicity

The relative binding affinity of 35 steroids for the glucocorticoid receptor was determined in experiments in which the competition of various unlabeled steroids with either [6,7-3H]dexamethasone or [1,2-3H]hydrocortisone for the cytosolic glucocorticoid receptor of cultured human keratinocytes was measured. The data obtained were correlated with steroid lipophilicity, measured as the partition coefficient of the steroid between 1-octanol and pH 7.4 aqueous buffer. The introduction of various substituents on the steroid molecule induced changes in the binding affinity and was associated in some cases with concomitant changes in steroid lipophilicity. The substitution by a 17 alpha-OH or 21-OH group leads in all cases to a decrease in steroid lipophilicity and to an increase in affinity. In contrast, 17 alpha-OAc and especially 21-OAc substitution on hydrocortisone and betamethasone causes a decrease in the steroid affinity for the receptor and an increase in steroid lipophilicity. The elongation of the ester chain from acetate to valerate in both position C-17 and C-21 leads to the increase in both the binding affinity for the receptor and the lipophilicity of steroids. However, all 21-esters showed lower binding affinity than the parent alcohol. The binding affinity of the highly lipophilic 17 alpha, 21-diester was found to be lower than that of the 17 alpha-ester but higher than that of the 21-ester or of the parent alcohol. Only in the series of 17 alpha- and 21-esters is there a correlation between the binding affinity of steroids for the glucocorticoid receptor and their lipophilicity.     

On the interaction between anthralin and DNA: A revision

Summary The interaction between anthralin and DNA in vitro was examined. According to our data, there is no evidence for a specific interaction between these substances. However, we found that the addition of small quantities of DNA or albumin significantly enhanced the stability of aqueous solutions of anthralin and markedly affected the rate of anthralin decomposition.     

Effect of vasoactive agents on prostanoids in suction blister fluid

Iontophoresis of histamine in the skin has been shown to release prostaglandins and arachidonic acid in suction blister fluid. Application of DMSO had a similar effect. No effect was found after using the following erythema and oedema irritants: scraping, vibration and ketocaine. Treatment with vasoconstricting drugs such as noradrenaline betamethasone and lidocaine-prilocaine mixture did not influence the prostaglandin or arachidonic acid levels.     

Growth and differentiation of human keratinocytes cultured on eye lens capsules

Summary The efficiency of the outgrowth of human epidermal and hair-follicle-sheath keratinocytes was studied using three different growth substrates: plastic, type-I collagen and bovine eye lens capsules (the Epicult system). It was shown that the eye lens capsule is the best substrate, since a higher percentage of cultures showed outgrowth, and the outgrowth of epidermal keratinocytes was much more rapid. This effect is related to the faster migration (not proliferation) of cells grown on lens capsules as compared to the two other substrates. The view that lens capsules can replace the basement membrane present in vivo was supported by the finding that two basement-membrane components, i.e., laminin and fibronectin, are present on lens capsules. It was shown that, in cultures grown on lens capsules, bullous-pemphigoid antigen is restricted to the basal layer, indicating that the differentiation of these cells is comparable to that of keratinocytes grown on irradiated, non-viable pig dermis.