Sleep apnea in end-stage renal disease patients: Impact on cardiovascular and neurological outcomes

INTRODUCTION

Sleep apnea (SA) is an important comorbidity in end-stage renal disease (ESRD) patients. The association between SA and cardiac and neurological disease is known. This study investigates the relationship between SA and cardiovascular and cerebrovascular outcomes in the ESRD population.

METHODS

In a retrospective cohort study, the United States Renal Data System was queried to identify ESRD patients aged 18-100 years in whom hemodialysis had been initiated between 2005 and 2013. Diagnoses of SA and clinical comorbidities were determined from International Classification of Disease-9 codes. Demographic variables were obtained from Centers for Medicare and Medicaid Services Form-2728. Logistic regression was used to examine the association of SA with myocardial infarction (MI) or with stroke, controlling for demographic and clinical variables.

RESULTS

Of 858,131 subjects meeting the inclusion criteria, 587 had central SA, and 22,724 had obstructive SA. The SA cohort was younger, more likely to be male and Caucasian compared to the non-SA cohort. Patients with SA also had more tobacco and alcohol use, hypertension, heart failure, and diabetes. Central SA (aRR = 1.69, 95% CI = 1.28-2.23) and obstructive SA (aRR = 1.15, 95% CI = 1.09-1.21) were associated with an increased risk of stroke but not MI.

CONCLUSION

In the ESRD population, a diagnosis of central SA or obstructive SA increased the risk of stroke, but not MI. Early identification and treatment of SA in the ESRD population may help reduce the risk of stroke in these patients.

Hashimoto's thyroiditis and renal transplant rejection

PURPOSE

Hashimoto's thyroiditis (HT) is a common autoimmune thyroid disorder that can disrupt thyroid function and homeostasis. As HT results from a dysregulated immune system, we hypothesized that these patients might be more susceptible to transplant failure; however, literature on this association is limited. The purpose of this study is to examine the association of HT with the risk of renal transplant failure.

METHODS

We utilized the United States Renal Database System dataset collected from 2005 to 2014 and compared the time from first renal transplant to transplant failure in end-stage renal disease (ESRD) patients with a HT diagnosis to ESRD patients without a HT diagnosis that underwent renal transplant.

RESULTS

A total of 144 ESRD patients had International Classification of Disease-9 claim codes for HT prior to renal transplant, amongst a total cohort of 90,301 renal transplant patients aged 18-100 and meeting criteria. Patients with HT were significantly more likely to be female, white, and to have a diagnosis of cytomegalovirus compared to patients without. ESRD patients with a HT diagnosis that underwent renal transplant had a significantly increased risk of renal transplant failure compared to those ESRD renal transplant patients without an HT diagnosis. There was a significantly increased adjusted hazard ratio for graft failure in patients with a HT diagnosis compared to those without.

CONCLUSION

Thyroid health and HT may play a significant role in the development of the increased risk of renal transplant failure observed in this study. Additional studies are needed to investigate the underlying mechanisms for this association.

Pine oil effects on chemical and thermal injury in mice and cultured mouse dorsal root ganglion neurons

A commercial resin-based pine oil (PO) derived from Pinus palustris and Pinus elliottii was the major focus of this investigation. Extracts of pine resins, needles, and bark are folk medicines commonly used to treat skin ailments, including burns. The American Burn Association estimates that 500,000 people with burn injuries receive medical treatment each year; one-half of US burn victims are children, most with scald burns. This systematic study was initiated as follow-up to personal anecdotal evidence acquired over more than 10 years by MH Bhattacharyya regarding PO's efficacy for treating burns. The results demonstrate that PO counteracted dermal inflammation in both a mouse ear model of contact irritant-induced dermal inflammation and a second degree scald burn to the mouse paw. Furthermore, PO significantly counteracted the tactile allodynia and soft tissue injury caused by the scald burn. In mouse dorsal root ganglion neuronal cultures, PO added to the medium blocked adenosine triphosphate-activated, but not capsaicin-activated, pain pathways, demonstrating specificity. These results together support the hypothesis that a pine-oil-based treatment can be developed to provide effective in-home care for second degree burns.

Protein kinase D distribution in normal human epidermis, basal cell carcinoma and psoriasis

BACKGROUND

Keratinocytes undergo a defined programme of proliferation and differentiation during normal stratification of the epidermis. Anomalies in the signalling pathways controlling this process probably contribute to the pathogenesis of hyperproliferative dermatological diseases, including psoriasis and basal cell carcinoma (BCC). We have previously proposed that protein kinase D (PKD) is a proproliferative signalling enzyme in keratinocytes and have speculated that abnormalities in its levels or regulation may contribute to hyperproliferative disorders of the skin.

OBJECTIVES

To determine if hyperproliferative human skin disorders are characterized by abnormal protein expression or distribution of PKD, normal human epidermis was compared with BCC and uninvolved and involved psoriatic epidermis.

METHODS

To examine protein expression, immunohistochemical analysis of human samples and Western blotting of neoplastic mouse keratinocytes was performed. Western analysis of neoplastic mouse cells using a phosphospecific PKD antibody allowed estimation of PKD activation status.

RESULTS

Normal human epidermis demonstrated predominant PKD protein expression in the stratum basalis, the proliferative epidermal compartment, with decreased relative expression throughout the suprabasal strata. Uninvolved psoriatic skin showed a similar pattern, but in contrast, psoriatic lesions demonstrated a diffuse distribution of PKD staining throughout all strata. The majority of BCCs examined showed significant PKD protein levels and, in those biopsies in which the levels could be compared, elevated PKD levels relative to normal epidermis. PKD levels and activation status were also increased in a neoplastic mouse keratinocyte cell line.

CONCLUSIONS

PKD was elevated or misdistributed in the hyperproliferative human skin disorders, BCC and psoriasis, as well as neoplastic mouse keratinocytes. We speculate that PKD exerts proproliferative and/or antidifferentiative effects in the epidermis, and that anomalous distribution and/or activation of PKD may be involved in precipitating or sustaining the disease process in BCC and psoriasis.

8-Cl-adenosine induces growth arrest without differentiation of primary mouse epidermal keratinocytes

In some cell systems, the antiproliferative effects of 8-Cl-cAMP, a site-selective cAMP analog specific for the type I cAMP-dependent protein kinase, are mediated by its metabolite, 8-Cl-adenosine. These effects were once thought to be specific to transformed cells. We investigated the ability of 8-Cl-adenosine to regulate growth and differentiation in primary cultures of mouse epidermal keratinocytes. A 24 h exposure of keratinocytes to 8-Cl-adenosine inhibited [3H]thymidine incorporation in a dose-dependent manner with an apparent IC(50) of 7.5 microM, and these effects were completely reversible. To determine the ability of 8-Cl-adenosine to induce differentiation of primary keratinocytes, we measured keratin-1 expression and transglutaminase activity, markers of early and later stages of keratinocyte differentiation, respectively. Interestingly, exposure of keratinocytes to 25 microM 8-Cl-adenosine for 24 h had no effect on keratin-1 expression or transglutaminase activity. The 8-Cl-adenosine-induced growth arrest of keratinocytes required uptake of the compound and was accompanied by an increase in protein expression of the cyclin-dependent protein kinase inhibitor p21(WAF1/Cip1). These results demonstrate that 8-Cl-adenosine inhibits growth in a non-transformed/non-immortalized cell system, possibly through an elevation in p21(WAF1/Cip1) protein levels, without inducing differentiation.

Elevated K(+) induces myristoylated alanine-rich C-kinase substrate phosphorylation and phospholipase D activation in glomerulosa cells

Elevated extracellular potassium concentrations ([K(+)](e)) are known to stimulate aldosterone secretion from adrenal glomerulosa cells in vivo and in vitro. The mechanism is thought to involve depolarization-elicited activation of voltage-dependent calcium channels and an increase in calcium influx. Until now protein kinase C (PKC) was thought not to play a role in the steroidogenic response to elevated [K(+)](e). In this report, we provide evidence in bovine adrenal glomerulosa cells to suggest that elevated [K(+)](e) increases PKC activity, as shown by an enhancement in the phosphorylation of myristoylated alanine-rich C-kinase substrate (MARCKS). Elevated [K(+)](e)-induced MARCKS phosphorylation was delayed and transient and was not the result of a local production of angiotensin II (AngII). MARCKS phosphorylation in response to elevated [K(+)](e) was not accompanied by phosphoinositide hydrolysis but was inhibited by a selective PKC inhibitor. Elevated [K(+)](e) also activated phospholipase D (PLD) in a delayed but sustained manner. We propose that the observed PLD activation mediates the elevated [K(+)](e)-induced MARCKS phosphorylation via PKC, although other factors may modulate this phosphorylation event.

ANPs effect on MARCKS and StAR phosphorylation in agonist-stimulated glomerulosa cells

Atrial natriuretic peptide (ANP) is a cardiac hormone that inhibits aldosterone secretion induced by all physiologic agonists. The purpose of this study is to explore ANP-induced changes in the phosphorylation of myristoylated alanine-rich C-kinase substrate (MARCKS) and the steroidogenic acute regulatory protein (StAR), in AngII or K(+)-stimulated glomerulosa cells. The data show that ANP completely inhibits the phosphorylation of MARCKS and partially inhibits that of StAR in cells stimulated with K(+). ANP also partially inhibits MARCKS phosphorylation but does not affect StAR phosphorylation in cells stimulated with AngII. These effects appear to be cGMP-independent and at least partially dependent on inhibition of protein kinase C (PKC). To our knowledge, this is the first report of ANP modulating either MARCKS or StAR phosphorylation in [(32)P]-labeled cells. The data also support the hypothesis that ANP inhibits aldosterone secretion acting as a step involved in cholesterol transport to the mitochondria.

Differential effects of agonists of aldosterone secretion on steroidogenic acute regulatory phosphorylation

The steroidogenic acute regulatory (StAR) protein mediates cholesterol transport within the mitochondria, and its phosphorylation is believed to be required for steroidogenesis. Increased extracellular potassium concentrations (K(+)), angiotensin II (AngII), and adrenocorticotropic hormone (ACTH) induce aldosterone secretion from bovine adrenal glomerulosa cells. We hypothesized that, although these agonists act via different signaling pathways, StAR phosphorylation should be common to their action. We studied the effects of K(+), AngII, and ACTH, at concentrations that yield comparable secretory responses, on StAR phosphorylation. All three agents induced significant increases in StAR phosphorylation although the response to ACTH was less than that of AngII and K(+). In cells stimulated with the protein kinase C (PKC) agonist 12-tetradecanoylphorbol 13-acetate (TPA), the Ca(2+) channel agonist BAY K8644, and the adenylate cyclase agonist forskolin, TPA caused a small but statistically significant increase in StAR phosphorylation while BAY K8644 and forskolin had no significant effect. Interestingly, the combination of TPA and BAY K8644 produced a larger increase in StAR phosphorylation than the agents alone. We conclude that in cultured bovine adrenal glomerulosa cells the PKC signaling pathway is most effective at inducing StAR phosphorylation but that there is no simple correlation between this event and aldosterone production.

Inhibition of [(3)H]thymidine transport is a nonspecific effect of PDMP in primary cultures of mouse epidermal keratinocytes

Inhibitors of sphingolipid metabolism are frequently used to investigate the role of ceramide and other sphingolipids as intracellular signaling molecules. For example, the inhibitor of glucosylceramide synthase D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) is commonly used to deplete glycosphingolipids and increase ceramide levels. Ceramide is known to induce growth arrest and differentiation of keratinocytes, and we hypothesized that PDMP would increase ceramide levels and induce growth arrest of primary cultures of mouse epidermal keratinocytes. As expected, PDMP increased ceramide levels and decreased the incorporation of [(3)H]thymidine into DNA, but surprisingly, PDMP was found to rapidly inhibit the intracellular transport of [(3)H]thymidine. This is likely due to a direct effect on nucleoside transport by PDMP and not due to elevations in ceramide levels because increasing ceramide levels by the addition of exogenous sphingomyelinase had no effect on [(3)H]thymidine transport. Furthermore, it is unlikely that the decreased [(3)H]thymidine transport is in response to growth arrest because PDMP had no effect on the cell cycle profile of keratinocytes. These results reveal that PDMP inhibits nucleoside transport independent of effects on ceramide levels or cell growth but probably by a direct effect on the nucleoside transport apparatus. Thus, this compound may be unsuitable for investigating the role of ceramide or other sphingolipids in some cellular processes.

Retinoid receptors: pathways of proliferation inhibition and apoptosis induction in breast cancer cell lines

In this study we investigated the effects of several selective agonist retinoids (specific for RAR alpha, RAR beta, RAR gamma, and RXR alpha, respectively) on the proliferation and apoptosis of human breast cancer cell lines. All these retinoids inhibit proliferation through apoptosis induction, but with some differences among the tested molecules and the three cell lines. In particular, estrogen receptor positive (ER+) cells display a higher sensitivity to RARs selective compounds, the RAR alpha selective compound being the most effective agent, while estrogen receptor negative (ER-) cells show a greater responsiveness to the RXR alpha selective retinoid. In all tested cell lines a potent antiproliferative and apoptotic effect was also displayed by a high dose of the RAR gamma selective compound. The apoptosis induction is associated with bcl-2 down-regulation, while p53 expression is not modified by any retinoid. Only in one cell line (ZR-75.1), after RAR alpha selective retinoid treatment is there an induction of RAR beta: therefore not only RAR beta induction but also other mechanisms may contribute to the growth inhibitory effect of retinoids in tested breast cancer cell lines.

Successful treatment of chronic hand eczema with oral 9-cis-retinoic acid

BACKGROUND

9-cis-Retinoic acid (9-cis-RA) has a particular pattern of binding and activating retinoid receptors. Treatment of chronic hand eczema is often refractory to conventional treatment.

OBJECTIVE

Evaluation of oral 9-cis-RA therapy in chronic hand eczema in a pilot study.

METHODS

Thirty-eight patients with refractory chronic hand eczema were treated in an exploratory open-label study with oral 9-cis-RA.

RESULTS

Twenty-one (55%) showed a very good response, 13 (34%) a good response, 2 (5.5%) a moderate response and 2 (5.5%) no response. Side effects were mild.

CONCLUSION

9-cis-RA is a valuable drug when given at low doses to patients with chronic hand eczema.

Effects of angiotensin II and adrenocorticotropic hormone on myristoylated alanine-rich C-kinase substrate phosphorylation in glomerulosa cells

Angiotensin II (AngII) is thought to stimulate aldosterone secretion from bovine adrenal glomerulosa cells in part via activation of protein kinase C (PKC), while adrenocorticotropic hormone (ACTH) functions through increases in intracellular cAMP levels and calcium influx. Rather than using invasive homogenization techniques as in previous studies, we chose to monitor PKC activity in intact glomerulosa cells in situ by measuring the phosphorylation of the endogenous PKC substrate, myristoylated alanine-rich C-kinase substrate (MARCKS). AngII enhanced MARCKS phosphorylation in a rapid, sustained manner; whereas ACTH induced a rapid and sustained inhibition of MARCKS phosphorylation. Studies using pharmacological agents to mimic various signals indicated that the AngII-induced MARCKS phosphorylation was due to PKC activation, and the ACTH-elicited decrease was mediated by increases in calcium influx rather than cAMP production. We propose that changes in the phosphorylation state of MARCKS, an actin-binding protein, may contribute to cytoskeletal rearrangements involved in steroidogenesis.

1,25-dihydroxyvitamin D3 induces phospholipase D-1 expression in primary mouse epidermal keratinocytes

The hormone 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) elicits the programmed pattern of differentiation in epidermal keratinocytes. Based on data indicating a potential role of phospholipase D (PLD) in mediating keratinocyte differentiation, we investigated the effect of 1,25(OH)2D3 on PLD expression. A 24-h exposure to 1, 25(OH)2D3 stimulated PLD-1, but not PLD-2, mRNA expression. This 1, 25(OH)2D3-enhanced expression was accompanied by increased total PLD and PLD-1 activity. Time course studies indicated that 1,25(OH)2D3 induced PLD-1 expression by 8 h, with a maximal increase at 20-24 h. Exposure to 1,25(OH)2D3 inhibited proliferation over the same time period with similar kinetics. Expression of the early (spinous) differentiation marker keratin 1 decreased in response to 1, 25(OH)2D3 over 12-24 h. Treatment with 1,25(OH)2D3 enhanced the activity of transglutaminase, a late (granular) differentiation marker, by 12 h with a maximal increase after 24 h. In situ hybridization studies demonstrated that the highest levels of PLD-1 expression are in the more differentiated (spinous and granular) layers of the epidermis, with little expression in basal keratinocytes. Our results suggest a role for PLD expression/activity during keratinocyte differentiation.

RARalpha antagonist Ro 41-5253 inhibits proliferation and induces apoptosis in breast-cancer cell lines

Ro 41-5253 is a RARalpha-selective antagonist that binds RARalpha but does not induce transcriptional activation and does not influence RAR/RXR heterodimerization and DNA binding. This retinoid inhibits proliferation and induces apoptosis in MCF-7 and ZR-75.1 estrogen-receptor-positive breast-carcinoma cells in a dose-dependent way. The anti-proliferative effect is more evident in ZR-75.1 cells than in MCF-7 cells and is probably mediated by anti-AP1 activity, a mechanism known to be implied in the action of several retinoids. In the induction of apoptosis also ZR-75.1 cells are more sensitive to treatment with Ro 41-5253 than MCF-7 cells. In ZR-75.1 cells an apoptotic/hypodiploid DNA peak is already evident after 2 days of incubation, whereas in MCF-7 cells it appears only after 4 days. The highest percentage of apoptotic cells, for both cell lines, is reached after 6 days of treatment. The apoptosis pathway is p53-independent and bcl-2 downregulation seems to be correlated with an increase in TGF-beta1 protein. The MDA-MB-231 estrogen-receptor-negative cell line is poorly responsive to Ro 41-5253 treatment, both in terms of proliferation inhibition and apoptosis induction. Ro 41-5253 has proliferation-inhibiting and apoptosis-inducing properties that are not mediated by transcriptional activation from retinoic-acid response elements. This retinoid antagonist seems to be a compound that exerts an anti-tumor activity but does not induce the toxic side effects of retinoids and might, therefore, be considered as a candidate for cancer therapy.

A potential role for ceramide in the regulation of mouse epidermal keratinocyte proliferation and differentiation

We have previously determined that sustained phospholipase D (PLD) activation is associated with differentiation induction in primary mouse epidermal keratinocytes. We therefore investigated the effect of two bacterial PLD on keratinocyte proliferation and differentiation. We found that Streptomyces sp. PLD was much less potent at inhibiting proliferation than S. chromofuscus PLD, with a half-maximal inhibitory concentration of 0.05 versus less than 0.001 IU per ml for S. chromofuscus PLD. Similarly, S. chromofuscus PLD stimulated transglutaminase activity more effectively and potently than S. sp. PLD. When we examined the formation of products by the two PLD, we found that the S. sp. PLD showed higher activity at all concentrations. Whereas the PLD from S. sp. is relatively inactive on sphingomyelin, S. chromofuscus PLD is known to hydrolyze both glycerophospholipids and sphingomyelin. Based on recent data indicating a role for ceramide in regulating cell growth and differentiation, we hypothesized that the ability of S. chromofuscus PLD to hydrolyze sphingomyelin might underlie its greater potency. Therefore, we examined the effect of exogenous sphingomyelinase and synthetic ceramides on DNA synthesis. We found that sphingomyelinase exhibited a potent concentration-dependent effect on [3H]thymidine incorporation, much like S. chromofuscus PLD. Synthetic cell-permeable ceramides (C6- and C2-ceramide) also concentration dependently inhibited DNA synthesis, with a half-maximal inhibitory concentration of approximately 12 microM. Finally, we obtained evidence suggesting that ceramide is generated in response to a physiologically relevant agent, because tumor necrosis factor-alpha, a known effector of sphingomyelin turnover in other systems and a cytokine that is produced and released by keratinocytes, increased ceramide levels in primary epidermal keratinocytes.

Induction of apoptosis in MCF-7 breast carcinoma cell line by RAR and RXR selective retinoids

Induction of apoptosis in MCF-7 breast carcinoma cell line by various retinoids was measured by cytofluorimetry and DNA fragmentation assay. Retinoids with marked or high selectivity for RAR alpha, RAR beta, RAR gamma or RXR alpha were tested. All these retinoids were capable of inducing apoptosis, in a dose- and time-dependent way. MCF-7 cell line expressed RAR alpha, RAR gamma and RXRs, but not RAR beta. Compared to untreated MCF-7 cells, after 2 days of incubation with each of the selective retinoids, a substantial increase in apoptotic cells was observed, even at the lowest concentration of 10(-8) M. Among the various analysed selective retinoids only slight differences were observed. All-trans retinoic acid and 13-cis retinoic acid induced apoptosis only after 6 days and 9-cis-retinoic acid after 4 days of incubation. Since all receptor selective retinoids substantially inducedapoptosis, it may be concluded that RAR alpha, RAR gamma and RXR alpha are able to mediate programmed cell death in the tested tumor cell line. Highly selective retinoid receptor agonists and antagonists may be useful for clarifying the function of retinoid receptors and for further progress in the field of cancer prevention and therapy by retinoids.

Sustained phospholipase D activation in response to angiotensin II but not carbachol in bovine adrenal glomerulosa cells

We have demonstrated previously that in bovine adrenal glomerulosa cells, phospholipase D (PLD) activity can indirectly result in the generation of sn-1,2-diacylglycerol (DAG) through its production of phosphatidic acid (PA) and the subsequent action of PA phosphohydrolase. Furthermore, the PLD-generated DAG can trigger aldosterone secretion. Therefore, we characterized PLD activation by two agonists, angiotensin II (Ang II) and carbachol, to determine if the activity of the enzyme might underlie sustained aldosterone secretion. We determined that Ang II-induced PLD activation occurred via the angiotensin-1 receptor (AT1), and that a specific AT1 antagonist, losartan, inhibited this activation, whereas the same concentration of the AT2-specific antagonist, PD 123319, had no effect. Ang II activated PLD with a dose dependence similar to that observed for aldosterone secretion, with slight increases in activity induced by 0.1 nM Ang II and maximal activation at 10 nM. We also found that Ang II induced a sustained activation of PLD, but that the effect of carbachol, a stable analogue of acetylcholine, was transient; PLD activity increased within 5 min of exposure to carbachol but then ceased by 15 min. Higher carbachol concentrations were also unable to sustain PLD activation. These results suggest that the Ang II-elicited activation of PLD is associated with a sustained increase in aldosterone secretion from glomerulosa cells and further provide the first evidence, to our knowledge, of differences in the kinetics of PLD activation in response to two physiologically relevant agonists. Finally, we speculate that this disparity correlates with different functional responses induced by the two agents.

Cloning and expression analysis of murine phospholipase D1

Activation of phosphatidylcholine-specific phospholipase D(PLD) occurs as part of the complex signal-transduction cascade initiated by agonist stimulation of tyrosine kinase and G-protein-coupled receptors. A variety of mammalian PLD activities have been described, and cDNAs for two PLDs recently reported (human PLD1 and murine PLD2). We describe here the cloning and chromosomal localization of murine PLD1. Northern-blot hybridization and RNase protection analyses were used to examine the expression of murine PLD1 and PLD2 ina variety of cell lines and tissues. PLD1 and PLD2 were expressed in all RNA samples examined, although the absolute expression of each isoform varied, as well as the ratio of PLD1 to PLD2. Moreover, in situ hybridization of adult brain and murine embryo sections revealed high levels of expression of individual PLDs in some cell types and no detectable expression in others. Thus the two PLDs probably carry out distinct roles in restricted subsets of cells rather than ubiquitous roles in all cells.

High-level expression of the retinoic acid receptor beta gene in normal cells of the uterine cervix is regulated by the retinoic acid receptor alpha and is abnormally down-regulated in cervical carcinoma cells

Retinoic acid (RA) is essential for regulation of epithelial cell differentiation. The intracellular effects of RA are mediated by RA-binding nuclear receptors, including the RA receptors (RARs) alpha, beta, and gamma. The ligand-activated receptors induce the transcription of target genes by binding to RA-responsive elements in the promoter regions. One target gene is the RAR beta gene, which encodes a potential tumor suppressor. Loss of RA inducibility of RAR beta gene expression is assumed to play a role in the development of several types of human carcinomas, including carcinomas of the uterine cervix. We have analyzed RAR beta gene expression in normal cervical cells and in cervical carcinoma cell lines. The results show that the RAR beta mRNA levels are high and RA inducible in the primary keratinocytes, whereas they are low and not inducible or only slightly inducible by RA in all of the cervical carcinoma cell lines analyzed. The basal and the RA-induced RAR beta mRNA levels tend to increase with senescence of the normal cells. Fusion of primary ectocervical keratinocytes with HeLa cervical carcinoma cells revealed that the characteristics of RAR beta gene expression of the normal cells are dominant over that of the tumor cells. Using synthetic retinoids with receptor-preferential agonist activities and a RAR alpha-specific antagonist, we show that RAR alpha is the major endogenous RAR subtype for induction of RA-dependent RAR beta gene expression. Taken together, our results indicate that abnormal downregulation of RAR beta gene expression may be an important step in the multifactorial process of cervical carcinogenesis.

Effects of all-trans-retinoic acid and 13-cis-retinoic acid on breast-cancer cell lines: growth inhibition and apoptosis induction

Interest has been increasingly focused on all-trans-retinoic acid (tRA) and 13-cis-retinoic acid (13cRA) in cancer chemoprevention and treatment. We have examined the in vitro effects of these 2 retinoic acids (RAs) on human breast-cancer cell lines MCF-7 and ZR-75.1 (both estrogen-receptor-positive, ER+) and MDA-MB-231 (estrogen-receptor-negative, ER-), in terms of inhibition of proliferation and induction of apoptosis. Both retinoic acids exerted an evident dose-dependent growth inhibition, although in the ER- cell line the anti-proliferative effect was obtained only with the highest concentration used; the anti-proliferative activity of tRA was more evident than 13cRA on all 3 tested cell lines. tRA and 13cRA induced apoptosis in MCF-7 and MDA-MB-231 cell lines, but not in ZR-75.1. The apoptotic phenomenon was clearly time-dependent, and in our experience it was not related to the arrest in a specific phase of cell cycle. After treatment with RAs the levels of bcl-2 were reduced in MCF-7, while in ZR-75.1 and in MDA-MB-231 no treatment-related modifications were observed. An analysis of estrogen-receptor status, used as a marker of differentiation, demonstrated that after treatment with RAs the levels of estrogen receptor (ER) decreased in ZR-75.1 only. Our study indicates that the anti-proliferative effects of RAs are sustained by induction of apoptosis in MCF-7 and MDA-MB-231 cells, while in ZR-75.1 cells an induction of differentiation without apoptosis was the prevalent mechanism of growth inhibition. Our results encourage further studies on in vivo effects of these retinoids in breast cancer.

Trial of isotretinoin and calcitriol monitored by CA 125 in patients with ovarian cancer

Twenty-two asymptomatic women with rising CA 125 levels after chemotherapy for ovarian cancer were entered into a trial of isotretinoin combined with calcitriol. Tumours were evaluated according to precise criteria based on serial CA 125 levels and by comparing regression slopes of CA 125 before and during therapy. There was no evidence based on CA 125 of any responses or significant change in tumour growth rate.

Interleukin-12 inhibits angiogenesis induced by human tumor cell lines in vivo

Tumor cell-induced angiogenesis, i.e., new blood vessel formation within tumor tissue, is an essential requirement for the growth of solid neoplasms. Interleukin-12 (IL-12) inhibits growth of a variety of experimental tumors in vivo. We tested whether antitumor activity of IL-12 is related to the inhibition of angiogenesis induced by tumor cell lines. Angiogenesis was induced in x-ray immunosuppressed Balb/c mice by intradermal injection of the following human tumor cells: T47D, originating from mammary carcinoma; A431, derived from vulval carcinoma; and Skv, established from bowenoid papulosis, Systemic treatment of the mice with murine IL-12 significantly decreased angiogenesis induced by human tumor cells in a time-and dose-dependent manner. Preincubation of human cells in vitro with IL-12 did not inhibit tumor cell-induced angiogenesis, suggesting that the antiangiogenic capacity of IL-12 is restricted to in vivo conditions. Treatment of the mice with rat antibody against murine interferon-gamma (IFN-gamma) resulted in counteracting the antiangiogenic effect of murine IL-12. Furthermore, human IFN-gamma inhibited the angiogenic activity of human tumor cell lines. This indicates that IFN-gamma is a mediator of the antiangiogenic effect of IL-12. The results show that the mechanism of antitumor action of IL-12 may depend not only on the immunostimulatory activity of this cytokine but also on its effect on tumor cell-induced angiogenesis. IL-12 should be considered as a potential candidate for the treatment of angiogenesis-dependent malignancies.

Vitamin D3 is a potent inhibitor of tumor cell-induced angiogenesis

Vitamin D3 derivative 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) exerts various biological effects in cells that possess vitamin D3 receptor (VDR), including enhancement of cell differentiation and inhibition of cell proliferation. These activities of 1,25(OH)2D3 might be responsible for its anti-neoplastic effects, as shown in various experimental systems. The aim of this study was to compare the anti-angiogenic activity of 1,25(OH)2D3, retinoids, and interleukin-12 (IL-12) in an experimental tumor cell-induced angiogenesis assay in mice. Tumor cell-induced angiogenesis assay was performed in x-ray immunosuppressed BALB/c mice by intradermal injections of human tumor cell lines of different origin. The injections resulted within 3 d in a local formation of new blood vessels, and the intensity of angiogenesis correlated with the number of injected cells. Systemic treatment of the mouse recipients with 1,25(OH)2D3 significantly decreased angiogenesis, comparable to the effect of retinoids (all-trans retinoic acid [RA], 9-cis RA and 13-cis RA) and of IL-12. In vitro preincubation of the cells with all compounds (except IL-12) led to the inhibition of their angiogenic capability in vivo. Moreover, combination of 1,25(OH)2D3 and retinoids resulted in a synergistic inhibition of angiogenesis. The results strongly suggest that anti-angiogenic compounds with relatively low toxicity (e.g., 1,25(OH)2D3, retinoids, and IL-12) and their combinations could be beneficial in the treatment of some angiogenesis-associated malignancies.

Efficacy of oral low-dose tretinoin (all-trans-retinoic acid) in lichen planus

BACKGROUND

Retinoids were shown to be effective in the treatment of both oral and cutaneous forms of lichen planus.

OBJECTIVE

Confirm the beneficial effect of low doses of oral tretinoin in lichen planus.

METHODS

Eighteen patients with lichen planus were treated in an open study for up to 19 months. Efficacy and safety data were recorded.

RESULTS

Complete remission was observed in 13 (72%) and marked improvement in 4 (22%) out of 18 patients. Six patients showed moderate and 12 had no side effects.

CONCLUSION

Tretinoin is a valuable drug when given at low doses to patients with lichen planus who failed to respond to other therapies.

Oral 9-cis-retinoic acid versus 13-cis-retinoic acid in acne therapy

BACKGROUND

9-cis-Retinoic acid (9-cis-RA) is as active as 13-cis-retinoic acid (13-cis-RA) in inhibiting the proliferation of cultured human sebocytes and in reducing the size of sebaceous glands of hamsters.

OBJECTIVE

Evaluate the anti-acne effect of 9-cis-RA compared to that of 13-cis-RA in a pilot study.

METHODS

Four young male patients with acne were treated in an open study consecutively with 9-cis-RA and 13-cis-RA given at similar doses.

RESULTS

No beneficial effects were observed with 9-cis-RA in any of the patients whereas all responded favorably to 13-cis-RA.

CONCLUSION

For the two retinoids tested, the anti-acne effect correlates with the sebosuppressive effect in humans.

Protein kinase C inhibits human hair follicle growth and hair fibre production in organ culture

In this study we have used a human hair follicle whole-organ culture system to examine the effects of 12-O-tetradecanoyl-phorbol-13-acetate (TPA), a potent activator of protein kinase C (PKC), on hair follicle growth and hair fibre production. Anagen hair follicles were isolated from human facial skin by microdissection and placed in suspension culture in supplemented Williams E medium. Hair follicle and hair fibre lengths were measured daily using an inverted microscope and cumulative growth values were calculated. Treatment with TPA resulted in a potent, dose-dependent inhibition of total cumulative hair follicle growth (IC50 = 1 nM). Hair follicles grew at a comparable rate for 4 days in the presence or absence of 10 nM TPA, after which growth of TPA-treated follicles ceased while control follicles grew by a further 0.8 mm over the subsequent 6 days. In contrast, 10 nM TPA treatment did not affect hair fibre elongation for a period of 8 days, after which TPA-treated fibre production ceased while control fibres grew by a further 0.79 mm over the subsequent 7 days. Incubation of hair follicles with TPA resulted in a 41% inhibition of hair fibre protein synthesis, as measured biochemically from the incorporation of 3H-leucine using a differential akali extraction method. The inhibitory effect of TPA on follicle growth was partially prevented by preincubation with the selective PKC inhibitor H-7, and almost completely prevented by preincubation with the more potent PKC inhibitor Ro 31-7549. Neither agent alone significantly affected follicle growth at concentrations that reversed the TPA response. These findings indicate that PKC is a negative regulator of hair follicle growth, and suggest that PKC may play a part in the transduction of follicular growth-inhibitory signals.

Biphasic effect of 1,25-dihydroxyvitamin D3 on primary mouse epidermal keratinocyte proliferation

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] has been proposed as a physiologic regulator of keratinocyte growth and differentiation. Utilizing a proliferative serum-free culture system, we have found that a physiologic (picomolar) concentrations this hormone stimulated proliferation of primary mouse epidermal keratinocytes; at higher (nanomolar to micromolar) doses, growth was inhibited by 1,25(OH)2D3. We investigated the nature of the signal transduction mechanism underlying the response to 1,25(OH)2D3 and observed little or no effect of either low or high concentrations of the hormone on cytosolic calcium levels or Fos expression. Furthermore, the protein kinase C inhibitor, Ro 31-7549, had very little effect on the growth inhibition induced by a high dose (1 microM) of 1,25(OH)2D3. This lack of rapid signal transduction events was consistent with the inability of a short (4-hour) exposure to 1,25(OH)2D3 to initiate a complete growth-inhibitory response as measured using [3H]thymidine incorporation. Our results indicate that physiologic concentrations of 1,25(OH)2D3 are required for optimal keratinocyte growth. Furthermore, we found no evidence of rapid effects of 1,25(OH)2D3 and suggest that in mouse epidermal keratinocytes, the response to this hormone is mediated by a slow transduction pathway, such as that activated by the intracellular 1,25(OH)2D3 receptor (VDR).

Retinoids, interferon alpha, 1,25-dihydroxyvitamin D3 and their combination inhibit angiogenesis induced by non-HPV-harboring tumor cell lines. RAR alpha mediates the antiangiogenic effect of retinoids

Retinoids combined with interferon alpha-2a (IFN alpha) or 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] have shown marked synergistic inhibitory effects on angiogenesis induced by tumor cell lines harboring DNA of oncogenic human papillomaviruses (HPV) type 16 or 18. This report demonstrates comparable effects of these compounds on angiogenesis induced by non-HPV-bearing transformed cell lines, including breast carcinoma (T47D) and vulval carcinoma (A431) cell lines. Systemic treatment of mice with all-trans retinoic acid, 13-cis retinoic acid, 9-cis retinoic acid, IFN alpha or 1,25(OH)2D3 significantly decreased tumor cell-induced angiogenesis (TIA). In vitro pretreatment of T47D and A431 cells with these compounds also led to inhibition of their angiogenic capability when tested in the TIA assay. The inhibitory effects of retinoids could be counteracted by a selective antagonist of the nuclear retinoic acid receptor RAR alpha, suggesting a RAR alpha mediated mechanism of angiogenesis inhibition. The antiangiogenic effect of retinoids could be significantly enhanced by combination with IFN alpha or 1,25(OH)2D3. The results provide a further basis for the use of combinations of retinoids with IFN alpha or 1,25(OH)2D3 in the treatment of angiogenesis-dependent malignancies.

Experimental basis of cancer combination chemotherapy with retinoids, cytokines, 1,25-dihydroxyvitamin D3, and analogs

Retinoids, cytokines as well as 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and analogs possess properties known to contribute potentially to cancer chemopreventive and chemotherapeutic effects. They induce cell differentiation, inhibit cell proliferation, suppress expression of viral oncogenes, and inhibit angiogenesis necessary for tumor growth. Since clinical combination chemotherapy of cytotoxic agents has proven superior to monotherapy, this modality might also be useful for other classes of antitumor drugs. A series of retinoids, such as all-trans-, 13-cis-, 9-cis retinoic acid, and acitretin, cytokines, 1,25(OH)2D3, and analogs have been investigated in model systems of differentiation, proliferation, viral oncogenes, and angiogenesis. The three classes of compounds have common effects but nevertheless show a variance depending on the particular representative of each class. Combination of compounds of the different classes led in the various models to a higher efficacy compared with the compounds given alone. Cytokines such as IFN alpha, IFN gamma, G-CSF, TNF alpha, IL-1, and IL-4 markedly potentiate the differentiation-inducing effect of retinoids. Cytokines as well as retinoids combined with 1,25(OH)2D3 and analogs synergistically enhanced differentiation induction in human transformed hemopoietic cell lines. On a series of human transformed epithelial cell lines a panel of cytokines, such as IFN alpha, IFN gamma, TNF alpha, TGF beta, and EGF acted synergistically with retinoids on inhibition of proliferation. This was also observed by combining retinoids with 1,25(OH)2D3 and analogs. Retinoids as well as interferons alpha and gamma have the capacity to suppress the oncogene expression of human papilloma viruses which are involved in induction and growth of certain malignancies such as cervical cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

Combination 13-cis-retinoic acid and interferon alpha-2a in the therapy of solid tumors

Preclinical data indicate that the combination of retinoids and interferons have synergistic antiproliferative and differentiating effects in some hematologic and solid tumor models. These observations have led to clinical trials in which 13-cis-retinoic acid (13cRA) 1 mg/kg/day was combined with interferon alpha-2a (IFN alpha) 3 or 6 x 10(6) U/day. The first two such trials produced exciting results: 50% response rate in patients with previously untreated stages IB-IVA cervix cancer and 68% in patients with advanced squamous cell skin cancer. These data led to a number of additional trials of the combination, but the high response rates seen in the initial cervix and skin trials have not been duplicated in the other squamous tumors tested (head and neck, lung, pretreated cervix). In addition, trials in two non-squamous histologies were negative (lung and melanoma). However, the regimen was not always studied in an optimal population of previously untreated patients and the negative results in pretreated cervix patients point to the relevance of this consideration. Nevertheless, the observation that the combination of 13cRA and IFN alpha (both of which bind to specific receptors and change gene expression) is able to induce regression in advanced tumors, must be regarded as highly important. Key questions to be addressed include an understanding of the biologic mechanism of specific tumor sensitivity (why some squamous tumors and not others?), and mechanisms of resistance in sensitive tumor types (e.g. cervix). Such data may lead to trials targeted to tumor types with defined biologic features having a high likelihood of clinical benefit. In the meantime, studies integrating this combination with other active treatment modalities such as radiation is warranted in cervix and skin carcinomas.

Cancer combination chemotherapy with retinoids: experimental rationale

Retinoids, cytokines as well as 1,25-dihydroxyvitamin D3 and its analogs are all classes of compounds with pleiotropic actions. They inhibit proliferation in human transformed epithelial cell lines and induce differentiation in human transformed hemopoietic cell lines. In a murine model of tumor cell-induced angiogenesis all three classes of compounds inhibit the formation of new blood vessels, necessary for supplying the growing tumor with oxygen and nutrients. Combinations of compounds from the three different classes lead to higher efficacy than the compounds administered as single agents. The effects of combinations vary depending on the individual representatives of the three classes and on the particular test models used. Additive, synergistic and potentiating effects have been observed. The results obtained in experimental systems raise hope that combination therapy might be useful in the treatment of certain human neoplastic diseases.

Regulation of fos-lacZ fusion gene expression in primary mouse epidermal keratinocytes isolated from transgenic mice

The expression of a fos-lacZ fusion gene was studied in primary mouse epidermal keratinocytes obtained from transgenic mice. This gene construct contains the entire upstream regulatory sequence of c-fos, and expression of the endogenous and fusion gene was shown by Northern analysis to correlate upon induction with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). Using a chromogenic substrate of beta-galactosidase, we also demonstrated that expression of the fusion gene product, like that of Fos, was localized to the cell nucleus. In addition, we showed that epidermal keratinocytes responded to dialysed fetal bovine serum (FBS), TPA and high-calcium medium with enhanced Fos-lacZ expression and an inhibition of proliferation. The time course of induction of Fos-lacZ expression was similar for dialysed FBS and TPA, with a peak approximately 2 h after exposure. Exposure for approximately 24 h to an elevated extracellular calcium concentration was required to elicit an increase in Fos-lacZ expression. The lack of an immediate effect of raising medium calcium levels on Fos-lacZ expression contrasted with the rapidity of its effect on DNA synthesis, which was significantly inhibited within 6-8 h. In addition, we found that the protein kinase C inhibitor Ro 31-7549 blocked Fos-lacZ expression induced by TPA but had little or no effect on that elicited by high calcium levels. Thus, although our results indicate that the fos gene product may be involved in mediating epidermal keratinocyte growth arrest in response to differentiative agents such as FBS, TPA and high medium calcium levels, the exact role of this gene product remains unclear.

Synergistic effect of retinoids and interferon alpha on tumor-induced angiogenesis: anti-angiogenic effect on HPV-harboring tumor-cell lines

Various retinoids and interferons exert anti-tumor effects both in experimental studies and in clinical trials. Recent reports indicate that they have a synergistic antineoplastic activity. Our study aimed to determine whether these synergistic anti-tumor effects are related to inhibition of tumor-cell-induced angiogenesis. A further aim was to compare the anti-angiogenic activity of various retinoids including 9-cis retinoic acid, a ligand for nuclear retinoic acid receptor RXR, given alone and in combination with interferon alpha-2a (IFN alpha-2a). An in vivo experimental model of cutaneous angiogenesis in the mouse was used. Angiogenesis was induced by intradermal injection of HPV16- or HPV18 DNA-harboring tumor-cell lines. All-trans retinoic acid (all-trans RA), 13-cis retinoic acid (13-cis RA) and 9-cis retinoic acid (9-cis RA) as well as IFN alpha-2a applied to mice intraperitoneally for 5 consecutive days before induction of angiogenesis resulted in significant inhibition of angiogenesis. Combination of retinoids with IFN alpha-2a led to a synergistic inhibition of angiogenesis, as compared to the effects of the drugs given alone. Similar results were obtained when tumor cells were preincubated in vitro with the compounds, before injection into untreated mice. Our findings on synergistic anti-angiogenic effects of retinoids and IFN alpha-2a could explain, at least partially, the anti-tumor efficacy of combined therapy with these agents, and provide support for the role of angiogenesis in tumor growth.

Inhibition of tumor cell-induced angiogenesis by retinoids, 1,25-dihydroxyvitamin D3 and their combination

Tumor-induced angiogenesis (TIA), i.e., the ability of transformed cells to stimulate new blood vessel formation is an important factor contributing to tumor growth and invasiveness. The antiangiogenic effect of the retinoids, all-trans retinoic acid, 13-cis retinoic and 9-cis retinoic acid, of 1,25-dihydroxyvitamin D3, and of their combinations were studied using an experimental system in vivo. TIA was induced in immunosuppressed mice by intradermal injection of the two human transformed keratinocyte lines, Skv-e2, harboring DNA of human papillomavirus (HPV) type 16, and HeLa, harboring HPV18 DNA. The three retinoids and 1,25-dihydroxyvitamin D3, when administered systemically to mice, before the angiogenesis assay significantly decreased TIA. Their combination led to a synergistic inhibition of TIA. These results provide the basis for the use of combination of retinoids and 1,25-dihydroxyvitamin D3 in treatment of neoplastic diseases.