William Regelson

Anti-glucocorticoid effects of dehydroepiandrosterone (DHEA)

For a long time DHEA was considered a physiologically inert steroid produced in large quantities by the human adrenal cortex. No biological function for DHEA was known except to serve as the precursor of sex hormones such as estradiol, testosterone and etiocholanolone. In the past decade there has been a tremendous surge in research to delineate the biological role of DHEA. Ex- tensive data published so far have shown that DHEA has many diverse physiological, biological and biochem- ical effects encompassing various cell types, tissues and organs [1-3]. As such DHEA has been shown to have effects in obesity, diabetes, cancer, aging, stress, immune responses, pregnancy and in cardiovascular and nervous 9 system pathophysiology. The physiological relevance of such global actions of DHEA is not clear at the present time, and thus no coherent theme has emerged which can put all these varied and sometimes confusing biolog- ical effects of DHEA in to proper perspective. Among the myriad of biological actions, the anti@u- cocorticoid properties of DHEA are now clearly emerg- ing. In fact, the anti-glucocorticoid action of DHEA may explain many of the seemingly diverse biological activities of DHEA, such as its effects on stress, obesity, diabetes, immune responses, and protection against acute lethal viral infections. We have therefore, focussed this review on the anti-glucocorticoid effects of DHEA. Another critical issue pertinent to DHEA is that de- spite its impressive and diverse biological effects, we have little insight as to the cellular and molecular mech- anisms by which its various biological effects are medi- ated. In general, it is difficult to assess whether the ac- tions of DHEA are due to DHEA itself, to its metabo- lites or a combinations of both. Therefore, for clarity and coherency, in this article first we describe the metab- olic fate of DHEA, then outline its apparent anti-gluco- corticoid actions and finally we address the issue of the mechanism of DHEA action.

Dehydroepiandrosterone (DHEA)–the Multifunctional Steroid

DHEA metabolites must be separately evaluated to determine if they have actions beyond their role as intermediates in the pathway of sex steroid synthesis. The unusually broad spectrum of biologic applications for DHEA suggests that its hormone action is not solely governed by receptor-mediated responses, o r glucocorticoid (GCS) antagonism, although the latter may explain a large measure of DHEA effects. Whether DHEA’s hormonal effects are target specific or state dependent requires further study, but the broad range of physiologic effects have clinical implications of therapeutic significance. To help the reader, recent broad reviews on DHEA and discussion of specific action have been published in our recent text,’ and in the preceding paper where we have discussed DHEA’s metabolic origins, immunologic effects and related glucocorticoid antagonism.’

Results with methyl-CCNU and DTIC in metastatic melanoma

This report is the result of an Eastern Cooperative Oncology Group (ECOG) study. Four hundred and 15 patients with inoperable metastatic malignant melanoma, excluding those with cutaneous metastases only, were randomized to one of three drug treatments: DTIC alone, methyl‐CCNU alone, or the combination DTIC plus methyl‐CCNU. Responses were seen in 14% of DTIC patients (19/127), 15% of methyl‐CCNU patients (18/119) and 14% of DTIC plus methyl‐CCNU patients (18/122). Duration of response was the same (14 weeks) for all three treatment groups. There was no difference among the treatments in achieving complete responses. Survival was improved significantly for responders (50 weeks) compared with nonresponders (15 weeks) regardless of treatment regimen. Toxicities were generally tolerable. DTIC caused significantly more gastrointestinal toxicity than methyl‐CCNU. Methyl‐CCNU caused significantly more bone marrow toxicity than DTIC. There were three drug‐related deaths. All occurred in patients on combination DTIC plus methyl‐CCNU. Important pretreatment characteristics that favor response are ambulatory status, female, less than 50 years old, no prior chemotherapy and no liver or brain metastases. Patients with favorable characteristics combinations had a 30% response rate, while those with unfavorable characteristic combinations had only a 9% response rate.

Dehydroepiandrosterone (DHEA)-the “Mother Steroid”

In the past we have viewed DHEA as the primary precursor of etiocholanalone or the more important sex steroids (FIG. I ) , as major decline following adrenalectomy does not produce gross symptoms of clinical withdrawal. The failure to recognize a DHEA deficiency state suggested that DHEA’s functional role is paraendocrine distinct from its action as a targeted excitatory hormone in the classical sense. To explain the above, we ascribed DHEA’s varied activity to the concept of hormonal “state dependency.”’ “State dependency” describes the varied action of a hormone based upon the expression of its action only within particular physiologic settings, independent of a specific end organ targeted effect. DHEA has also been likened to an “anti-hormone” which “cannot serve to ‘excite’ in the true classical sense of hormone action, but ‘de-excites’ metabolic processes which overproduce when DHEA is in short supply.”’ DHEA may act by buffering or antagonizing the action of corticosteroids to modify stress-mediated injury to tissue, an action which may be critical to the degenerative diseases of aging. The data also suggest that DHEA may modulate insulin o u t p ~ t . ~ ~ Recent broad reviews of DHEA?.’-” and more specific presentations on immunity, cardiovascular diseases, obesity, carcinogenesis, hepatic function, mitochondrial metabolism, insulin action, and receptor availability have been published.” Daynes and Araneol? have presented evidence that DHEA or DHEAS may be a natural mediator of T cell responses, and may be important to restoration of youthful antigenic responses in aged mice.I3 Based on the action of DHEA in stimulating neural cells and enhancing memory, Roberts14 postulated that DHEA works through the stimulation of cyclic GMP. Based on the observations of Majewska et ul.,Is he suggested that the levels of GMP may be the final common pathway for DHEA action on varied cellular responses. DHEA, as a neurosteroid synthesized by the brain,’6,17 may also act through modulation of GABA.14 DHEA stimulates peroxisomal induction with marked increase in liver weight,I8 which can be a factor in both the cause and prevention of tumor induction.I9 DHEA influences mitochondria1 and lipid me tabo l i~m”~~*-?~ and is a potent noncompetitive inhibitor of glucose-6-P04 dehydrogenase (Gd-PD), which controls the pentose shunt and the generation of extramitochondrial NADPH.2S

Molecular mechanism of RU 486 action: a review.

Steroid hormones are known to have profound tissue specific physiological and pathophysiological effects in higher organisms. These hormones are involved in mammalian growth, development, differentiation, maturation and aging. Therefore, understanding the mechanisms by which steroid hormones exert various biological, biochemical and physiological effects are of great scientific interest and the subject of intense current research efforts. It is now widely believed that steroid hormones being hydrophobic enter target cells by simple diffusion and bind with high affinity and limited capacity to the specific receptor proteins localized in the cytoplasm (glucocorticoid and mineralocorticoid receptors) or nuclear (estrogen, progesterone) compartment. The binding of steroids to cytoplasmic or nuclear receptors results in conformational changes called activation or transformation which enable the steroid-receptor complex to bind tightly to specific transcriptional enhancer DNA sequences (also called hormone-responsive element) thus activating or suppressing transcription of genes under control of steroid hormones. Since steroid hormones have profound physiological and pathophysiological effects, it is highly desirable to have pure and potent steroid antagonists which may block the given steroid effects in both in vitro and in vivo situations. In spite of three decades of efforts to find potent antagonists for glucocorticoids and progesterone, the useful antagonist was not discovered until 1981, when a group of French scientists in Roussel UCLAF first introduced RU 486, (17 [3-hydroxy-lla (4-dimethylaminophenyl)-17a-l-propynyl-estra-4,9-dien-3-one), a compound with both antiprogestin and antiglucocorticoid activities [1, 2]. Accumulated data have demonstrated various clinical applications of RU 486. For example, RU 486 is used for the treatment of the hypercortisolemia of Cushings syndrome [2], inoperable meningioma and glucocorticoid-induced hypertension [3]. RU 486 is a well known chemical for its antiprogestin, abortifacient or contraceptive action [2, 4-8]. RU 486 is also a possible anticancer agent for the treatment of hormone-dependent breast cancer [4]. In addition, RU 486 also has beneficial effects in aiding cervical dilation, lactation and the treatment of endometriosis. The importance of RU 486 extends beyond its clinical applications, since RU 486 has been reported as a pure

Immunotherapy with autologous white cell infusions (“lymphocytes”) in the treatment of recurrent glioblastoma multiforme. A preliminary report

Autologous leukocytes (107 to 109), obtained with the Haemoneticss Leukaphoresis apparatus, were inoculated directly into recurrent glioblastoma tumors via indwelling catheters or by direct intratumoral injection through existing craniotomy openings. The rational use for autologous leukocyte (lymphocyte) infusions was based on in vitro autologous lymphocyte cytotoxicity to glioblastoma cells in the absence of serum inhibitory factors. Seven of 17 patients treated had life expectancy under 1 month; all patients had received definitive surgery, and all but two received radiation, nitrosourea chemotherapy and/or dexamethasone, and showed evidence of clinically recurrent disease. Following autologous leukocyte infusion (lymphocyte/granulocyte ratio 1:1), eight patients sustained clinical improvement and were alive up to 17 months later. No neurotoxicity ascribable to the procedure has been observed. One patient, who was comatose at the time of single leukocyte infusion, returned to full activity and lived for 17 months without an increase in tumor mass by brain scan. These results suggest that infusions of autologous leukocytes (lymphocyte‐monocytes) directly into glioblastoma may be a viable additional treatment for glioblastoma and certainly warrants further evaluation.

Melatonin: A Rediscovered Antitumor Hormone? Its Relation to Surface Receptors; Sex Steroid Metabolism, Immunologic Response, and Chronobiologic Factors in Tumor Growth and Therapy

Melatonin (5-methoxy-N-acetyltryptamine) is a lipidsoluble derivative of 5-hydroxytryptamine, which is produced clinically via the pineal gland under the influence of sympathetic neural tone governed by diurnal variation in light exposure. Melatonin secretion is maximal with the onset of darkness and it controls diurnal rhythms (i.e., temperature and sleep) and the seasonal Zeitgebar involving reproductive behavior, the seasonal pelt, and pigmentation. The complicated patterns of these relationships between pituitary-hypophyseal, light exposure, and the pineal gland that may be mediated by melatonin have been discussed in a number of reviews (1-13). These observations have resulted in a recent conference on melatonin in humans (14) where melatonin diurnal and seasonal rhythms have been shown to be a factor in sleep and seasonal affective disorders. Recent observations suggest that melatonin deserves clinical trial to enhance or modify response in hormonally sensitive tumors and to determine if melatonin’s impact on chronobiologic control can improve the circadian

Physicochemical characterization of [3H] DHEA binding in rat liver

Dehydroepiandrosterone (DHEA), the native clinical steroid and steroid precursor, may have a targeted physiologic role. A high affinity (Kd 2.3nM) and steroid specific [3H] DHEA binding macromolecule in male Sprague-Dawley rat hepatic cytosol suggests that DHEA may have receptor mediated physiologic action. 3[H] DHEA binding was highest in the liver followed by kidney and testis cytosols. Sulfhydryl reagents such as N-ethylmalemide and iodoacetamide inhibited the binding of [3H]DHEA by up to 60-70%. The DHEA-macromolecular complex was stable at 35 degrees C. and addition of 5mM molybdate or 0.3M KCl increased stability. Interestingly, rat liver cytosol, specific binding at 4 degrees C increased by almost 40-50% with addition of 0.1M NaSCN or 0.3M KCl. Sucrose gradient analyses showed a 7-8 S macromolecular complex in the low salt and 3-4 S complex under high salt conditions. The [3H] DHEA- macromolecular complex shows minimal temperature dependent activation in vitro at 25 degrees C as judged by binding to DNA-cellulose. The results suggest a specific high affinity macromolecule for DHEA in rat liver cytosol with unique physicochemical properties.

THE RETICULOENDOTHELIAL EFFECTS OF INTERFERON INDUCERS: POLYANIONIC AND NON-POLYANIONIC PHYLAXIS AGAINST MICROORGANISMS *

Polyanions control numerous biologic proce~sesl-~ and have been shown to alter host resi~tancel*~,~ and the polycarboxylic, pyran copolymer (divinyl ether maleic anhydride, NSC-46015 diveema) is undergoing clinical test for antitumor and antiviral activity6. the synthetic polynucleotide, polyriboninosinic-cytidylic acid (p0ly:IC) is under clinical trial. capa~ity~*~, stimulate inmunologic response3, 5~8, inhibit serum complement9 and produce a biphasic phagocytic reticuloendothelial response with inhibition followed by stimulation of liver von Kupffers cells antl splenic subcapsular and internodular cells4,8. This has led to pyrans evaluation in cellular immtnity wherein it has been shown to delay skin transplant rejection in ratdo. Pyran has also been shown to inhibit adjuvant induced polyarthritis, periostitis and tendinitisll. addition, metabolismf2 and can effect intravascular coagulation by blocking the conversion of fibrinogen to fibrinl3. Similarly,

Keratopathy After Oral Administration of Tilorone Hydrochloride

Two patients given tilorone HCl orally for varying periods of time had clinical and histopathologic ocular changes. Retrospective study of 14 cancer patients who were taking tilorone HCl orally revealed that three patients had similar ophthalmic findings accompanied by the appearance of blue halos around pinpoint light sources. Examination revealed a diffuse clouding of the epithelium sometimes associated with subepithelial infiltrates. Abnormalities seen histologically included cloudy swelling of the epithelium and cytoplasmic inclusions. By electron microscopy these were found to be myelinoid bodies. Gas chromatography and mass spectrophotometry showed that tilorone HCl was present in the cornea and conjuctiva. Visual acuity was not affected and these changes were slowly reversible with the cessation of therapy. Biomicroscopic and conjunctival cytologic examination may serve to indicate the drugs storage and potential damage in the body.