To determine whether the nongenomic actions of E2 have any beneficial effect on cardiac function following traumahemorrhage and whether those effects are mediated via the PI3K/ Akt pathway. Summary Background Data: Since studies suggest that both genomic and nongenomic pathways are involved in mediating the salutary effects of 17␤-estradiol (estradiol) following trauma-hemorrhage, we examined if the nongenomic effects of estradiol on cardiac function after trauma-hemorrhage involve the PI3K/Akt pathway. Methods: Male Sprague-Dawley rats (ϳ300 g) underwent traumahemorrhage (mean blood pressure, 40 mm Hg for 90 min, then resuscitation). Estradiol conjugated to bovine serum albumin (BSA) (estradiol-BSA; 1 mg/kg estradiol) with or without estrogen receptor antagonist (ICI 182,780), PI3K inhibitor (Wortmannin), or vehicle was injected intravenously during resuscitation. At 2 hours after trauma-hemorrhage or sham operation, cardiac output, stroke volume, heart rate, mean arterial pressure, and ϮdP/dt were measured. Cardiomyocyte PI3K, p-Akt, Akt protein expressions and apoptosis were also determined. One-way ANOVA and Tukey's test were used for statistical analysis. Results: Cardiac output, stroke volume, and ϮdP/dt decreased significantly after trauma-hemorrhage. Administration of estradiol or estradiol-BSA significantly improved these parameters of cardiac function. Although trauma-hemorrhage decreased cardiomyocyte PI3K protein expression and Akt phosphorylation (p-Akt), estradiol or estradiol-BSA treatment following trauma-hemorrhage prevented such decreases in cardiomyocyte PI3K protein expressions and p-Akt. The increase in cardiomyocyte apoptosis was also prevented in rats receiving estradiol-BSA. Co-administration of ICI 182,780 or Wortmannin abolished beneficial effects of estradiol-BSA on cardiac functions following trauma-hemorrhage. Conclusion: The PI3K/Akt pathway plays a critical role in mediating the nongenomic salutary effects of estradiol on cardiac function following trauma-hemorrhage.

HL60 promyeloid cells express both classes of oestrogen receptor (ERalpha and ERbeta). We show that hydrolysis of oestrone sulphate by steroid sulphatase is a major source of oestrone in HL60 cells, and that most of the released oestrone is not metabolized further to 17beta-oestradiol. Treatment of HL60 cells with retinoids or 1alpha,25-dihydroxyvitamin D3 increased steroid sulphatase mRNA and activity in parallel with the induction of CD11b, an early marker of myeloid differentiation that is expressed before the differentiating cells stop proliferating. Use of agonists and antagonists against retinoid receptor-alpha and retinoid receptor-X revealed that both classes of retinoid receptor can drive steroid sulphatase up-regulation. Steroid sulphatase activity fluctuates during the cell cycle, being highest around the transition from G1 to S phase. During the differentiation of HL60 cells induced by all-trans-retinoic acid or 1alpha,25-dihydroxyvitamin D3, there is increased conversion of 17beta-oestradiol into oestrone by an oxidative 17beta-hydroxysteroid dehydrogenase. Treatment of Caco-2 colon adenocarcinoma cells with all-trans-retinoic acid or 1alpha,25-dihydroxyvitamin D3 also increases 17beta-oestradiol oxidation to oestrone. An increase in local oestrone production therefore occurs in multiple cell types following treatment with retinoids and 1alpha,25-dihydroxyvitamin D3. The possible involvement of locally produced oestrogenic steroids in regulating the proliferation and differentiation of myeloid cells is discussed.

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Neutrophil and monocyte differentiation can be induced in HL60 leukaemia cells by all-trans-retinoic acid (ATRA) and 1K K,25-dihydroxyvitamin D 3 (D 3 ), respectively, whose differentiating effects can be enhanced by exposure tò anti-inflammatory agents' and steroids. We have provided evidence that this potentiation is via inhibition of the activity of an enzyme of the aldoketoreductase (AKR) family, but had failed to identify expression of known AKRs in HL60 cells. In this study, we have identified a previously unclassified aldoketoreductase family member (termed HAKR e) that is expressed in HL60 cells. HAKR e is dramatically and transiently upregulated in HL60 cells within 24 h of exposure to ATRA, further supporting the proposition that a member(s) of this family of enzymes play(s) a role in controlling cell growth and/or differentiation.z 1998 Federation of European Biochemical Societies.

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