1. STEROID HORMONE/NUCLEAR RECEPTORS
Dec

2. Steroid Biosynthesis Derived from cholesterol
Estrogen receptor α, β
(ERα, ERβ)
Androgen receptor (AR)
Mineralocorticoid receptor (MR)
Progesterone receptor A, B
(PRA, PRB)
Glucocorticoid
receptor (GR)
This slide to show how one steroid can be made into another

3. Glucocorticoids: Therapeutic Uses
Endocrine Disorders:
-acute or chronic adrenal insufficiency
-congenital adrenal hyperplasia
Non-endocrine Disorders:
-rheumatoid arthritis
-bronchial asthma
-inflammatory bowel disease
-inflammatory dermatosis
-organ transplantation
-allergic diseases
-occular diseases
Dec

4. Glucocorticoids: Side Effects
Dec

5. Dec

6. Drug systemic effect + inactive metabolite
Schematic representation of the disposition of inhaled drugs
Mouth
Deposition
~90% swallowed
Lung
Pulmonary
absorption
Lung
Topical effect
~2-10%
Liver
First pass
Metabolism
(inactivation)
GI Tract
BLOOD STREAM
Drug systemic effect + inactive metabolite
Dec

7. New Approaches for Glucocorticoid Treatment of Asthma
fluticasone propionate (Flovent ®)
cytochrome P450 3A4
(Liver)
FP-17ß-carboxylic acid derivative (INACTIVE)
COOH
Dec

8. Nuclear Localization of Steroid Receptors
Unliganded GR
Liganded GR
Unliganded/
Liganded ER
NOTE: Steroid Receptors Shuttle Between the Nucleus & Cytoplasm
Dec

9. Dec

10. Ligands for Various Orphan Receptors
Dec

11. Metabolic Pathways of Nuclear Receptor Ligands
Chawla et al Science 294:1866, 2001
Dec

12. Active ingredient of Gugulipid Gum resin of Commiphor mukl
In use since 600 BC
Antagonist of FXR
(Farnesoid or Bile Acid Receptor)
Lowers cholesterol and triglyceride
levels
Dec

13. Active ingredient in St. John’s Wart Extract of Hypericum perforatum
In use over 2000 years
Ligand for PXR
(Pregnane X or Xenobiotic Receptor)
Induction of CYP3A4
Dec

14. Steroid Hormone Receptors: Limited Forms
Androgen AR
Mineralocorticoids MR
Estrogens ERa
ERb
Progesterone PRA
PRB
Glucocorticoids GR
GRb
Dec

15. TWO RECEPTORS FOR ESTROGEN ER & ER
AF-1
DBD
LBD
AF-2
ER-a
ER-
Homology:
23%
86%
24%
58%
12%
Note: Both types of ER can form homodimers (e.g. ER/ER) or heterodimers (i.e. ER/ER)

16. Estrogen Receptor Distribution Within the Body
ER
ER, ER

17. ERa ERß Dominant Roles for Select ER Subtypes
Apoptosis in prostate cancer cells
Enhancement of glucose stimulated insulin secretion (pancreatic ß cells)
Folliculogenesis
Reduced intestinal inflammation (reduced colon carcinoma risk)
Stimulation of uterine growth
Bone metabolism
Mammary gland development
Negative feedback in hypothalamus

18. EMERGING RESEARCH
SELECTIVE ER ISOFORM AGONISTS

19. Phytoestrogens (from soy)
NONSTEROIDAL ER ACTIVATORS
Phytoestrogens (from soy)
Contain flavinoids (e.g. Genistein), which are weakly estrogenic
Schaefer O, et al., (2003) 8-Prenyl naringenin is a potent ERalpha selective phytoestrogen present in hops and beer. J Steroid Biochem Mol Biol Vol. 84: pp

20. NONSTEROIDAL ER ACTIVATORS Xenoestrogens or Environmental Estrogens
Industrial chemicals or their byproducts with estrogenic activity
Effects on human health are controversial but recent studies suggest that long term exposure (i.e. BPA) may increase risk of obesity and breast cancer in women
Bisphenol (BPA)
Polychlorobiphenyls (PCBs)

21. Diethylstilbestrol (DES)
NONSTEROIDAL ER ACTIVATORS
Diethylstilbestrol (DES)
DES is a potent nonsteroidal estrogen that is not rapidly metabolized
DES was prescribed between 1948 and 1971 to prevent miscarriages in high risk pregnancies
It’s use was discontinued after female offspring of women taking DES during pregnancy were found to have an increased risk of rare cancer (vaginal clear cell adenocarcinoma).

22. Dec

23. Accessory DNA-binding Factors Required!!
Glucocorticoid Response Unit of the PEPCK Gene
HNF4
HNF3 GR GR
COUP +1
CEBP/ß
TBP
-27
-445
-410
-380
-90
-325
Accessory DNA-binding Factors Required!!
(Can impart tissue-specificity)
NOTE: Phosphoenolpyruvate carboxykinase (PEPCK) gene is glucocorticoid regulated in liver only
Dec

24. Estrogen Regulated Promoters
Association of other Transcription Factors ER
FH + ER
Genome wide analysis (from Myles Brown Lab) FH FH ER ER FH ER

25. DNA-Induced Conformational Changes in Glucocorticoid Receptor:
Impact on Gene Regulatory Properties
Transcriptional Activation
Transcriptional Repression
GR Only
GR + Other Transcription Factors GR GR GR GR GR
Dec
Direct DNA binding Direct DNA Binding Tethering

26. CHROMATIN: Higher Order DNA Compaction Within the Nucleus
Histone Core:
2 copies each of H2A, H2B, H3, H4 (all basic proteins-rich in Arg, Lys residues)
Dec

27. Histone Acetylation/Deacetylation
Dec

28. NOTE: Rubinstein-Taybi Syndrome caused by mutations in CBP.
Other transcription factors
NOTE: Rubinstein-Taybi Syndrome caused by mutations in CBP.
NOTE: Overexpression of some coactivators (e.g. Amplified in Breast Cancer-1 [AIB-1]) associated with hormone-independent breast cancer
Dec
(From Glass and Rosenfeld)

29. NOTE: HDAC inhibitors in clinical trials for cancer treatment
Other transcription factors
NOTE: HDAC inhibitors in clinical trials for cancer treatment
(From Glass and Rosenfeld)
Dec

30. Nuclear Receptors as Drug Targets
Reproductive or Endocrine Disorders
Hormone-dependent Cancers (ER-breast cancer, AR- prostate cancer)
Metabolic Diseases (PPAR- for Type 2 Diabetes and Metabolic Syndrome)
NOTE: Ligands for nuclear receptors are small ligands that are cell permeable
CELL OR TISSUE-SPECIFIC LIGANDS POSSIBLE?
Dec

31. Steroid Hormone Action Steroid Hormone Action
raloxifene N H O
estradiol
4-hydroxytamoxifen (
Z-OHT )
Z-pseudo
diethylstilbestrol S
Estrogen receptor
ligands
elicit different tissue-specific responses
Estrogen
target tissues
Breast
Uterus
Bone
agonist
antagonist
partial agonist
Liver
CNS
????
Selective Estrogen Receptor Modulators (SERMs)
Dec

32. Estrogen Receptor Ligand-binding Domain: Ligand-induced Conformational Change
Helix 12 Contacts:
Coactivator proteins!
Dec

33. Dec

34. MECHANISM OF SERM ACTION
SERM as Agonist Recruitment of Coactivators!
(e.g. Tamoxifen in uterus)
SERM as Antagonist Recruitment of Corepressors! (e.g. Tamoxifen in breast)
Dec

35. Anabolic Steroids THERAPEUTIC ANDROGEN PREPARATIONS
Greatest Ratio of Protein Anabolic Effects (i.e. increase in muscle mass) To Virilizing Effects
Oxandrolone
Stanozolol
Dec

36. Anabolic Steroids THERAPEUTIC ANDROGEN PREPARATIONS
Tetrahydrogestrinone (THG)
Metabolized quickly and had been difficult to detect since it degrades during standard gas chromatography and mass spectrometry procedures
~20% potency of DHT in stimulating prostate, seminal vesicle and levator ani muscle weight in the mouse
Toxicity profile unknown
Dec

37. Current Status of SARMs
Bhasin S et al. (2006) Nat Clin Pract Endocrino Metabol 2: 146–159

38. PPARs in Human Physiology
Dec

39. PPAR-d: New Drug Target for Metabolic Syndrome?
Oral Therapy for Type 2 Diabetes: Sites of Action
Oral therapy with various classes of antidiabetic agents improves glycemic control in patients with type 2 diabetes by targeting specific defects.         
Hyperglycemia may develop from three distinct but interactive abnormalities:
Increased hepatic gluconeogenesis
Decreased insulin secretion from the pancreas
Decreased peripheral glucose uptake by muscle and fat.
Carbohydrate ingestion results in postprandial hyperglycemia in insulin-deficient individuals. The alpha-glucosidase inhibitors (ie, acarbose and miglitol) work in the small intestine to delay absorption of carbohydrates.
Decreased insulin secretion is related to dysfunction of ß-cells in the pancreas. Insulin secretagogues (i.e., sulfonylureas, repaglinide, and nateglinide) work at the pancreas to increase insulin secretion. When ß-cells can no longer produce insulin, exogenous insulin is needed.
Insulin resistance at the hepatic level results in increased hepatic glucose production. The biguanide, metformin (and, to a lesser extent, the TZDs) primarily work by reducing hepatic glucose production (Goldstein, 1999).
The TZDs primarily (and, to a lesser extent, metformin) work to improve insulin sensitivity in peripheral tissues. (DeFronzo, 1999; Resignato, 1999).
DeFronzo. Ann Intern Med 1999;131:
Goldstein. Diabetes Technol Ther 1999;1:
Resignato. Trends Endocrinol Metab 1999;10:9-13.
Barish GD (RM Evans Lab) J Clin Invest : 590–597. PPARδ: a dagger in the heart of the metabolic syndrome

40. PPAR-d: New Drug Target for Metabolic Syndrome?
Oral Therapy for Type 2 Diabetes: Sites of Action
Oral therapy with various classes of antidiabetic agents improves glycemic control in patients with type 2 diabetes by targeting specific defects.         
Hyperglycemia may develop from three distinct but interactive abnormalities:
Increased hepatic gluconeogenesis
Decreased insulin secretion from the pancreas
Decreased peripheral glucose uptake by muscle and fat.
Carbohydrate ingestion results in postprandial hyperglycemia in insulin-deficient individuals. The alpha-glucosidase inhibitors (ie, acarbose and miglitol) work in the small intestine to delay absorption of carbohydrates.
Decreased insulin secretion is related to dysfunction of ß-cells in the pancreas. Insulin secretagogues (i.e., sulfonylureas, repaglinide, and nateglinide) work at the pancreas to increase insulin secretion. When ß-cells can no longer produce insulin, exogenous insulin is needed.
Insulin resistance at the hepatic level results in increased hepatic glucose production. The biguanide, metformin (and, to a lesser extent, the TZDs) primarily work by reducing hepatic glucose production (Goldstein, 1999).
The TZDs primarily (and, to a lesser extent, metformin) work to improve insulin sensitivity in peripheral tissues. (DeFronzo, 1999; Resignato, 1999).
DeFronzo. Ann Intern Med 1999;131:
Goldstein. Diabetes Technol Ther 1999;1:
Resignato. Trends Endocrinol Metab 1999;10:9-13.