Introduction to Hormone-Dependent Cancers (Breast/Prostate)

Question 1

What are hormones?

Answer 1

Hormone = A Chemical messenger produced by specialised cells usually within an endocrine gland and it is released into the bloodstream to have an effect on another part of the body.

Hormones can be chemicals/peptides/proteins

Question 2

Where are hormones produced? - Endocrine Glands

Answer 2

Brain:
Pineeal gland , Hypothalamus and Pituitary

Thorax:
Thryoid gland and Thymus gland

Abdomen:
Pancreas, Kidney, Adrenal cortex
(stomach,liver,intestines)

Testes (Male)
Ovaries+Uterus (Female)

slide 4

Question 3

How can hormones be classified ?

Answer 3

Steroid hormones - Small, lipid-soluble molecules (testosterone)

Peptide/protein hormones (insulin)

Modified amino acid/amine hormones (adrenaline)

Question 4

What are steroid hormones ?

Answer 4

Steroid hormones = small, lipid-soluble molecules synthesised from cholesterol in adrenal cortex

All steroid hormones have a basic backbone 4-ring structure (of cholesterol).

Cholesterol is converted to biosynthetic precursors in adrenal cortex

Cholesterol – Adrenal cortex – Gonadal tissues

Question 5

Outline the process of steroid synthesis

Answer 5

Cholesterol
In the adrenal cortex (secretes primary hormones):
Main corticosteroids and mineralocorticoids synthesised in the adrenal cortex

Androgenic and estrogenic precursors are released into the blood stream (less potent forms of the final hormone)

Gonadal tissues:
Androgens and oestrogens produced in target organs e.g. testes and ovaries take up less potent hormone which produce active hormone (oestrogen, testosterone), then released into the bloodstream

Question 6

What are some examples of steroid hormones ?

Answer 6

Steroid hormones:

• Androgen (male steroid) - Testosterone
• Estrogen - Estradiol
• Progestogen - Progesterone
• Corticosteroid - Cortisol
• Mineralocorticoid - Aldosterone

Question 7

What are the sex steroid hormones?

Answer 7

Sex Steroid Hormones
Oestrogen (ovaries), Testosterone (testes).
These are responsible for:
Sexual dimorphism between males and females.
The development of the secondary sexual characteristics :
-Growth spurt
-Body hair growth
-Gonadal development
-Voice change
-Breast growth
-Accessory organs in the reproductive organs -prostate in men

Question 8

How do steroid hormones work ?

Answer 8

They work systemically, have effects on several tissues simultaneously.

Females - Oestrogen controls menstrual cycle, breast tissue development, fertility, reproductive organ development , secondary sexual characteristics (body hair)

Males - Testosterone controls reproductive organs, supportive organs (prostate), development of sexual characteristics in men (deep voice, body hair)

Question 9

What is the steroid hormone mechanism of action?

Answer 9

Steroid hormones = Small 4-ringed structure; Lipophilic molecules = easily enter cells by passing through plasma membrane

Once they enter the cell, steroid hormone binds to nuclear receptors; bind in cytoplasm + cause effects in nucleus

1. The steroid hormone (lipophilic) circulates in the blood then enters the cell and binds to its nuclear receptor.
2. Binding causes a conformational change in the receptor causing it to dissociate from cytoplasmic chaperone proteins and translocate into the nucleus .
3. In the nucleus, Steroid-Receptor Complex binds to DNA at specific sequences called Steroid Response Elements (short sequences of DNA found in the promoter region of steroid responsive genes)
4. Steroid receptor then functions as a transcription factor and recruits the gene transcription machinery, induces gene expression

slide 20, 21

Question 10

What are the key characteristics of Steroid Nuclear receptor ?

Answer 10

Ligand binding domain (LBD) - Binds specific steroid molecules with high affinity

DNA binding domain (DBD) - Binds specific DNA sequences

Activation function domain (AF1 and 2) - Recruits gene transcription machinery , some receptors have a secondary AF2 domain towards the C-terminal

The same basic domains and structure are shared with many of the major nuclear recpetors

Question 11

What happens when nuclear receptors bind steroid hormones ?

Answer 11

When these receptors bind steroid hormones they are activated = they are caled Ligand-Activated Receptors

-The binding of steroids to ligand binding domain causes a physical restructuring of the polypeptide chains (conformational change) in the receptor, activating it

Question 12

What are ligand activated transcription factors ?

Answer 12

slides 24,25

Nuclear R = Ligand Activated Transcription Factor:

Ligand binds to nuclear R = R activates + dimerises + translocates from cytoplasm into nucleus + binds DNA specific sequences (Hormone Response Elements). On the DNA (promoter/Steroid-Responsive Gene), Receptor recruits gene activation proteins+chromatin modifiers to initiate gene transcription

Question 13

The DNA binding domain contains ………….., which are essential for ……………

Answer 13

• 2 zinc fingers domains
• Nuclear receptor binding to the specific Hormone Reponse Element

4 cysteine residues = sulfur-containing aas, bind to Zinc atom, forming a zinc finger domain. 2 zinc finger domains in close proximity = required for specific DNA binding

Question 14

1 steroid hormone receptor can ………….. genes

Answer 14

1 steroid hormone receptor can upregulate/downregulate many genes

Genes include functional tissue-specific genes , cell cycle and proliferation genes and genes involved in tissue development and differentiation

Question 15

What are hormone response elements ?

Answer 15

Hormone Response Elements = Specific DNA sequences found in the promoters of hormone responsive genes.

Palindromic

Question 16

How does nuclear R bind to DNA Hormone Response Elements?

Answer 16

DNA-Binding Domain of Nuclear R contains zinc fingers which recognise + bind to the specific Hormone Response Elements sequences

Question 17

What is the Nuclear Receptor Super Family?

Answer 17

• 48 nuclear receptor genes
• Common domain structure
• Activated by ligand binding

slide 30,31

Question 18

What are the main steroid receptors / ligands and abbreviations ?

Answer 18

• ER - Oestrogen R - oestradiol, oestrone, oestriol
• AR - Androgen R - testosterone, dihydrotestosterone, androstenedione
• PR - Progestagen R - progesterone, pregnenolong
• GR - Glucocorticoid R - cortisol, cortisone
• MR - Mineralocorticoid R - aldosterone

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Question 19

Nuclear Rs have high homology in which domain?

Nuclear Rs differ in which domain?

Answer 19

DNA-binding domain = high homology

Ligand-binding domain = differ

Question 20

Which steroid Rs for breast cancer?

Which steroid R for prostate cancer?

Answer 20

Breast cancer Steroid Rs - Oestrogen R (ER) + Progesterone R (PR)

Prostate cancer - Androgen R (AR)

Question 21

The breast is an……….gland that produces …………..
The breast is composed of …………., which ……………
The milk-producing part of the breast is organized into …………………
Within each lobe are …………………………
The milk travels through ………………..
The ducts ………. and come together into ………….., which eventually ………….

Answer 21

apocrine
milk for infants
glands and ducts
produce the fatty breast milk
15-20 sections (lobes).
smaller structures (lobules), where milk is produced.
a network of tiny tubes (ducts)
connect
larger ducts
exit the skin in the nipple.

Question 22

What are apocrine glands ?

Answer 22

The mammary gland is a specialised type of exocrine gland (apocrine gland)

Apocrine glands = specialised exocrine glands in which a part of the cell’s cytoplasm breaks off, releasing the contents

Endocrine glands - secrete substances directly into bloodstream
Exocrine glands - secrete substances out onto a surface via duct

Question 23

What is exocrine glands ?

Answer 23

Secrete substances out onto a lumen/cavity/surface/onto skin via a duct

Question 24

What is an endocrine gland ?

Answer 24

These secrete substances directly into the bloodstream

Question 25

What are the 2 types of glands ?

Answer 25

Exocrine - Duct ,lumen cavity or into skin Endocrine - Into the blood

Question 26

What is the mammary gland tissue structure ?

Answer 26

Mammary epithelium consists of 2 cell compartments: - Luminal - form a single layer of polarised epithelium around the lumen duct, luminal cells produce milk during lactation. - Basal - the cells that don't touch the lumen, basally orientated myoepithelial cells in contact with the basement membrane, contract milk outwards during lactation slide 41

Question 27

What are the 2 major phases in mammary gland (breast) development?

Answer 27

- Hormone-independent - from embryonic development up to puberty - Hormone-dependent - thereafter during puberty, menstrual cycle and pregnancy

Question 28

What is the function of oestrogen in the normal breast?

Answer 28

Estrogen (+growth hormone+cortisol) drives the expression of genes involved in cellular proliferation +differentiation of breast Hormone-dependent mammary gland development occurs after puberty - oestrogen causes ductal elongation + triggers side branching. In the adult, oestrogen maintains mammary gland tissue + primes the tissue for effects of progesterone during pregnancy - milk production

Question 29

What is the normal progesterone activity in the normal breast

Answer 29

Oestrogen = primary initial growth of breast cancer Progesterone receptor gene is switched on by oestrogen receptor. It increases branching of the ducts Prolonged activity - leads to more side branching and lactogenic differentiation (prolactin hormone) slide 45+notes

Question 30

Outline the changes in breast tissue by oestrogen +progesterone +prolactin

Answer 30

slide 45+notes

Question 31

What is breast cancer ?

Answer 31

Breast cancer occurs when abnormal cells in the breast grow + divide in an uncontrolled way and eventually form a tumour Breast cancer starts in the breast tissue most commonly in the cells which line the milk ducts of the breast Main risk factors - Age, lifestyle (smoking, obesity), genetic familial factors

Question 32

What is the Breast Cancer Aetiology ?

Answer 32

Age - Risk ↑ with age - mostly 50+yo Genetic mutations to certain genes - BRCA1, BRCA2 - genes involving DNA repair. Inherit these mutations = ↑ risk breast+ovarian cancer Reproductive history - Menstrual cycle <12 years + menopause >55 years = ↑ hormone exposure. First pregnancy 30yo+. Not breastfeeding. No full term pregnancy. ↑ breast cancer risk Previous treatment using radiation therapy to the chest/breast (e.g.lymphoma) = ↑risk breast cancer Not physically active Overweight/Obese Taking hormones - Hormone Replacement Therapy Oral contraceptives Alcohol

Question 33

What is Ductal Breast Carcinoma In Situ (DCIS)

Answer 33

Breasts are made up of lobules (milk -producing glands) and ducts (tubes that carry milk to the nipple) -which are surrounded by glandular , fibrous and fatty tissue DCIS = Cancer cells develop within duct + remain within duct. Cancer cells have not spread outside ducts into surrounding tissue

Question 34

Outline Lobular Breast carcinoma in situ (LCIS)

Answer 34

LCIS = Abnormal cells form in the milk glands (lobules) in the breast. Uncommon Not breast cancer but ↑ risk

Question 35

Where do majority of breast cancers arise?

Answer 35

Luminal cells which express ER.

Question 36

What is ER(positive) and ER(negative)?

Answer 36

The majority of breast cancers are ER (+ve) which means they can be treated hormonally. ER(-ve) however have a poor prognosis. Develop not from luminal cells but other cells (basal cells etc.). Cannot be treated hormonally. Chemotherapy.

Question 37

Which cancer subtypes have better prognosis?

Answer 37

ER+ve/PR+ve breast cancer have a better prognosis PR indicates that ER is active bc PR is oestrogen-dependent gene PR - therapeutic target to treat breast cancer

Question 38

How is oestrogen involved in breast cancer?

Answer 38

In normal breast, ER controls functions such as cell proliferation,development and differentiation in a highly controlled manner. In breast cancer , ER signalling pathway is subverted and becomes uncontrolled. ER ability to bind DNA and open chromatin stops working and is used to transcribe many genes , non-coding RNAS and miRNAS ER then governs cancer cell proliferation + controls and influence many genes involved in metastasis, invasion +adhesion

Question 39

How can we target ER in breast cancer and why ?

Answer 39

Mammary gland is ER-sensitive+dependent tissue Breast cancer cells retain this sensitivity and dependency for oestrogen Oestrogen = key driver of breast cancer growth Switch off ER signalling = switch off the cancer growth ER targeting is the Achilles heel of breast cancer (ER targeting)

Question 40

How can we inhibit ER signalling ?

Answer 40

Biopsy samples are analysed for ER expression and 75% of breast cancers are ER +ve Therefore these women are candidates for specific treatments that block ER activity

Question 41

How can we stop oestrogen receptor from functioning ?

Answer 41

Oestrogen binds to its receptor at the ligand binding site which causes ER to dimerise and translocate into the nucleus where it binds DNA and recruits in proteins for gene transcription. e.g.co activators ,chromatin remodifiers,RNA polymerase Full activation of the ER: AF1 and AF2 are activated, triggering full gene transcription = cell growth - Breast cancer growth

Question 42

How can we inhibit Oestrogen action ?

Answer 42

Pharmaceutically competitively blocking oestrogen binding to receptor - Degrading the ER protein No ER signalling = no breast cancer cell growth

Question 43

What is Fulvestrant (Faslodex)?

Answer 43

Fulvestrant is an analogue of oestradiol Fulvestrant competitively inhibits binding of estradiol to the Oestrogen receptor with a binding affinity that is 89% that of oestradiol

Question 44

How does Fulvestrant cause ER degradation?

Answer 44

Fulvestrant-ER binding impairs receptor dimerization and receptor translocation into nucleus = blocks ER from working. + Any fulvestrant-ER complex that enters the nucleus is transcriptionally inactive because both AF1 and AF2 are disabled. The fulvestrant-ER complex is unstable, causing accelerated degradation of the ER protein No gene transcription

Question 45

Outline the mechanism of action of Tamoxifen

Answer 45

Tamoxifen binds to ER at the ligand binding site Tamoxifen = partial agonist = does not cause full activation of ER. Mixed activity - Activates ER in the uterus + liver. But acts as ER antagonist in breast tissue Tamoxifen = Selective Estrogen Receptor Modulator (SERM) Tamoxifen-bound ER does not fold properly and the AF2 domains do not function

Question 46

Describe Tamoxifen bound ER

Answer 46

slide 65

Question 47

What happens when Tamoxifen binds to the ER?

Answer 47

Tamoxifen binds to the ligand binding site and causes ER partial activation = conformational change = Only activates 1 of the activation domains (AF1). ER remains partially active = stops breast tissue activity slide 66

Question 48

What are aromatase inhibitors?

Answer 48

When ovaries are no longer functional in post menopausal women , potential sources of estrogen come from the peripheral conversion of androgens by aromatase enzyme. Aromatase enzyme is present in multiple organs - adipose tissue,brain,blood vessels ,skin ,bone, endometrium, breast tissue Androgens = testosterone, adrenal androgens (androstenedione) Low levels of Androgens are present in females

Question 49

What is the mechanism of aromatase?

Answer 49

Aromatase converts oxygen (ketone, androgen) → OH(alcohol, oestrogen) Androstenedione + aromatase = estrone Testosterone + aromatase = estradiol Aromatic group and alcohol differentiates estrogens and androgens slide 68+notes

Question 50

What are the 2 types of aromatase inhibitors ?

Answer 50

Type 1: Androgen analogues, bind irreversibly to aromatase (=suicide inhibitors). Duration of inhibitory effect depends on rate of de novo synthesis of aromatase. e.g. Exemestane Type 2: Contain a functional group within the ring structure that binds the heme iron of the cytochrome P450 of aromatase, interfering with the hydroxylation reaction. e.g. Anastrozole

Question 51

What is the main function of the prostate ?

Answer 51

Prostate function: Produces prostatic fluid that forms semen when mixed with the sperm produced by the testes

Question 52

Where is the prostate gland located and what is it made up of ?

Answer 52

Located just under bladder in the abdomen Exocrine gland, Apocrine gland Composed of glandular tissue which produce a system of ducts that secrete the fluid Composed of luminal epithelila cells which sit on basal epithelial cells. Luminal epithelial cells line the duct Ducts produce prostatic fluid and it then joins sperm+seminal fluid

Question 53

What are the 3 phases of development of a normal prostate gland? What can sometimes occur to prostate development in old age?

Answer 53

- Hormone-independent from embryonic development up to puberty - Hormone-Dependent Enlargement during puberty - Hormone dependent maintenance thereafter in adulthood -Reactivation of prostate growth in old age = Hyperplasia, Prostate Cancer

Question 54

What are some abnormalities of the prostate ?

Answer 54

Inflammation - due to infection. Prostatitis-Inferility Dysregulated growth of prostate. Benign : Benign prostatic hyperplasia. Malignant: Prostate cancer

Question 55

What are the symptoms of prostate cancer ?

Answer 55

- Frequent urination - Poor urinary stream - Urgent need to urinate - Hesitancy whilst urinating - Lower back pain - Blood in urine - Compressed urethra bc prostate under bladder. prostate enlargement = presses on bladder. + urethra passes through prostate gland = compresses it, reducing urine flow.

Question 56

Where does prostate cancer start ?

Answer 56

Originate in the luminal epithelial cells 1. Luminal epithelial cells Hyperproliferates, forming prostateintraepithelial neoplasia (PIN) 2. Then become Invasive Adenocarcinoma = Prostate cancer cells fill lumen and then invade outwards from the prostate slide 84

Question 57

How can we detect prostate cancer ?

Answer 57

- Digital rectal examination (DRE) - PSA test-blood sample: Antibody based assay. Damaged prostate = PSA enters blood. - Ultrasound of prostate gland - To detect tumour outside prostate capsule

Question 58

Describe the process of prostate cancer staging

Answer 58

When prostate cancer is diagnosed; Biopsy is carried out to stage prostate cancer to guide treatment TNM classification of malignant tumours: T = Size of primary tumour N=Number of lymph nodes involved M= Metastasised or not - PET scan T1: Small localised tumour T2: Palpable tumour - DRE T3: Tumour has escaped the prostate gland T4: Local spread to pelvic region to surrounding organs (bladder, seminal vesicles)

Question 59

What is N+ in prostate staging ?

Answer 59

N0= No cancer cells found in lymph nodes N1+ 1 positive lymph node (<2cm across) N2= ,1 positive lymph node or 1 between 2-5 cm across N3=Any positive lymph node . 5 cm across

Question 60

What is M+ metastatic ?

Answer 60

Has the cancer metastasised and where (PET scan detects this ) M1a =Non regional lymph nodes M1b=bone M1c =other sites

Question 61

How can the biopsy sample of prostate cancer be graded ?

Answer 61

1. Normal prostate - clear luminal structure, ordered tissue glandular morphology 2. Hyperplasia - abnormal growth of prostate 3. High grade carcinoma - disordered structure, cancer cells in lumen As it progresses there is a loss of glandular structure + irregular structure

Question 62

What is the Gleason grading system ?outline this

Answer 62

The Gleason grading system (1-5) = Helps evaluate patient prognosis using prostate biopsy samples Prostate cancer staging predicts prognosis + guides treatment Cancer with ↑ Gleason score = more aggressive and worse prognosis

Question 63

What are the stages of the Gleason grading system?

Answer 63

slide 91 1.Small uniform glands (Well differentiated ) 2.More stroma between glands 3.Distinctivly infiltrative margins (Moderately differentiated ) 4.Irregular masses of neoplastic glands (Poorly differentiated /Anaplastic) 5.Only occasional gland formation

Question 64

What are the different prostate cancer treatments ?

Answer 64

slide 92

Question 65

What gene changes can increase risk of prostate cancer ?

Answer 65

Inherited BRCA1 /BRAC2 gene mutations Men with lynch syndrome

Question 66

What are some of the risk factors of prostate cancer ?

Answer 66

``` Age - risk ↑ with age Race - ↑ African-American Geography - ↑ Western countries Family history - BRCA1 gene ↑ prostate cancer risk Gene changes/inherited - BRCA1/BRCA1, Lynch syndrome Diet Obesity Chemical exposure - Firefighters Prostate inflammation - Prostatitis STIs - gonorrhea, chlamydia ```

Question 67

What is the PTEN gene ?

Answer 67

PTEN = A phosphatase that antagonises the phosphatidylinositol 3 kinase signalling pathway (cell growth) PTEN is the only known 3' phosphatase counteracting the PI3K /AKT pathway Loss of PTEN = ↑ growth factor signalling Loss of PTEN = ↑ cell growth + proliferation

Question 68

What is TMPRSS2_ERG fusion

Answer 68

TMPRSS2_ERG fusion = a fusion gene which is most frequent in prostate TMPRSS2 = driven by Androgen Receptor Transcription Factor. ERG = proto-oncogene Fusion causes a strong proliferation signal, driven by testosterone

Question 69

Outline the androgen receptor signalling (AR)

Answer 69

AR is located in the cytoplasm associated with many chaperone proteins Testosterone is converted into a more potent agonist as it crosses into the prostate. DHT binds the AR testosterone is converted by 5-a -reductase . DHT then bind s to the AR with higher affinity =dimerisation. Translocation to the nucleus ,binds DNA in promoter regions Coactivator recruitment SLIDE

Question 70

Each class of steroid binds to

Answer 70

a unique nuclear R

Question 71

Prostate gland is ............-sensitive, .......-dependent | Most common androgen is ............., produced in ...............

Answer 71

androgen-sensitive androgen-dependent testosterone produced in testes

Question 72

AR = nuclear R protein that binds testosterone. | Mechanism of action of ARA

Answer 72

Testosterone (lipophilic) circulates in blood, passes through plasma membrane. prostate cell converts testosterone → DHT(more potent) by 5-alpha reductase. DHT binds AR w high affinity = activates AR + AR dimerises. AR translocates into nucleus, where it binds specific DNA sequences (Androgen Response Elements) in Promoters of Androgen Target Genes. Recruit Gene transcription machinery + coactivators to express target gene -> target protein -> cell growth

Question 73

What is the Achilles Heel of prostate cancer?

Answer 73

AR is the Achilles Heel of prostate cancer Switch off AR signalling = switch off cancer growth slide 116

Question 74

Pathway of Testosterone Action in the Cell

Answer 74

- Adrenal glands: cholesterol -> androgen precursors - Precursors circulate in bloodstream, reach testes. Testes: androgen precursor -> testosterone - Testosterone circulates in blood, reaches prostate gland. Prostate gland: testosterone -> DHT (↑ potent) - AR binds DHT, translocates into nucleus, binds DNA, recruits cofactors, causes gene transactivation = cell/tumour growth slide 117

Question 75

How to inhibit testosterone synthesis?

Answer 75

Inhibit adrenal androgen production = lack androgen precursors

Question 76

Steroid Hormones – Reactions in adrenal cortex | How to use adrenal androgen reactions to inhibit AR?

Answer 76

Main androgen precursors produced: androstenedione, dihydroepiandrosterone. Formed in adrenal gland, then circulate in blood, then converted to testosterone in testes Abiraterone inhibits androgen-producing enzymes = no adrenal androgen production = ↓ testosterone

Question 77

Tight control mechanism b/w brain +testes. | How to use this to ↓ testosterone production?

Answer 77

Hypothalamus secretes GnRH which targets pituitary, pit releases FSH+LH. FSH+LH circulate in blood, reach testes, stimulate testosterone production. –fb of testosterone on hypothalamus Inhibit HPG axis – GnRH antagonist = ↓ testosterone production

Question 78

Inhibit testosterone -> DHT

Answer 78

- Inhibit testosterone -> DHT (more potent) - 5 alpha-reductase inhibitor = Finasteride - Resembles androgenic intermediate = stops DHT production in prostate - Commonly used to reduce growth in Benign Prostate Hyperplasia (BPH)

Question 79

Inhibit androgen-AR binding

Answer 79

Competitive Androgen Antagonists Compete w testosterone for ligand binding site in AR Bicalutamide Testosterone binding = alpha-helix conformational change activates AR. Androgen antagonist binding = no alpha-helix conformational change = inactive AR slide 129

Question 80

Prostate cancer requires ......... for growth

Answer 80

androgens - testosterone

Question 81

go through ppt slides 132-143