thyroid carcinoma with specific empahsis on papillary thyroid carcinoma, history, risk factors, involved signalling pathway of MAPK, world wide pathogenesis status, its proposed targetting, involvmetn in cancer types

1. CANCER GENETICS PRESENTATION
PTC
PAPILLARY THYROID CARCINOMA/CANCER
PRESENTED BY: SAIMA BARKI
DEPARTMETN OF BIOCHEMISTRY
QUAID-e-AZAM UNIVERSITY, ISLAMABAD
PAKISTAN

2. OUTLINE:
• Thyroid gland cancers
• Prevalance
• Bird eye view
• Risk factors
• Molecular Pathway Dissection
• Aliases
• Location
• RET
• RET fact sheet
• RET/PTC invitro
• BRAF
• RAF Protein Structure
• Signalling pathway and elucidation
• Involvement in other cancers
• Clinical studies
• Therapeutics
• conclusion
• Refrences 2

3. THYROID CANCER
3

4. PTC PREVELANCE
4

5. PTC- A BIRD EYE VIEW
• FULL NAME: Papillary Thyroid Carcinoma
• NATURE: Involved gene are Proto-Oncogen
• MOLECULAR BASIS1:
a.Genetic recombination
b.Point mutation
• Pathogenesis nature2:
a. Radiation induced
b. Sporadic
• SIGNALLING PATHWAY3:
MAPK pathway
• LESIONS:
a. Solitary
b. Multifocal lesions
1. Fagin JA. 2005
2. Kondo T, et al., 2006
3. Nikiforov YE. 2008
5

6. RISK FACTORS
• PTC- more prevalent of the all thyroid cancer
• Central role in constitutive activation of MAPK pathway effectors.
• RISK FACTORs:
• Radiation( ionizing radiation)
a. Nuclear accident (japan nuclear event, chernobyl nuclear event).
b. Hedgehog patients- head and neck region radiotion therapy.
c. Radiation given throuugh IV during medical tests and therapy
TUMOR MARKER:
Thyroglobulin
MALIGNANCY NATURE:
1. Mostly benign
2. Very less metastatic, to lumph nodes of neck.
3. Distant spread to lungs and bones uncommon.
6

7. PTC-MOLECULAR PATHWAY DISSECTION
• MUTATIONS TYPES1:
– Point mutation,
– Genetic rearrangment:
• EFFECTED GENES3:
• RET
• BRAF
• RAS
• NTRK
Genetic alteration
1 Sporadic
Tumors(%)
Radiation-
InducedTumo
rs (%)
RET/PTC
rearrangement
approx. 40 66-87
NTRK rearrangement < 5 6
BRAF rearrangement 1 11
BRAF point mutation 40–45 0–4
RAS point mutation 10–15 0
71. Nikiforow, et al., 2002
2. Unger et al., 2004

8. ALIASES FOR RET and BRAF
Aliases for RET Gene
• RET Receptor Tyrosine Kinase
• Cadherin Family Member 12
• Ret Proto-Oncogene
• Cadherin-Related Family Member 16
• Rearranged During Transfection
• Proto-Oncogene C-Ret
• EC 2.7.10.1
• CDHF12
• CDHR16
• PTC
• Ret Proto-Oncogene (Multiple Endocrine
Neoplasia And Medullary Thyroid
Carcinoma 1, Hirschsprung Disease)
Aliases for B- raf Gene
• BRAF1 3 4
• RAFB1 3 4
• Serine/Threonine-Protein Kinase B-Raf
• B-Raf Proto-Oncogene, Serine/Threonine
Kinase 2 3 5
• V-Raf Murine Sarcoma Viral Oncogene
Homolog B1 3 4
• V-Raf Murine Sarcoma Viral Oncogene
Homolog B 2 3
• Proto-Oncogene B-Raf 3 4
• B-Raf Proto-Oncogene Serine/Threonine-
Protein Kinase (P94) 3
• Murine Sarcoma Viral (V-Raf) Oncogene
Homolog B1 3
GENE CARDS

9. RET AND B-RAFGENE LOCATION
RET GENE:
B-RAF GENE:
GENE CARDS
9

10. RET
Tyrosine kinase receptor, Normally no or low level in follicular epithelium 1
Transmembrane protein with extracellular 4 cadherin repeats, hydrophobic TM and intracellular tyrosine kinase domain
LIGAND: GDNP
Ligand binding→dimerization of receptor→activation of downtream signalling
Normal funcitonality:
1. Cell differentiation,
2. Growth
3. Migrationn
4. Survival
Protooncogene→oncogene by chromosomal recomination and point mutation
2. RET RECOMBINATION:2
Chromosomal recombination- illegitimate expresion of fusion protein(chmeric protein)-fusion of intracellur tyrosine kinase
domian with 5' of partner gene or N-terminal of heterologous gene.
3. Several Forms:
RET/PTC 1-70% Paracentric inversion of 10q fusion of RET with H4/D10S170 gene.
RET/PTC 3-26% Paracentric inversion of 10q fusion of RET with RFG/ELE1 gene.
4.RET/PTC Rearrangemnt causes:3
Radiation induced- 66-87%,
sporadic cases-40%,
kids more prone as compared to adults
1. Nikiforov YE. 2008
2. KondoT. et al. 2006
3. Ciampi R. et al 2005
10

11. RET/PTC FACT SHEET
11

12. GENETIC RECOMINATION EVENT
DOUBLE STRANDED BREAK AND GENE FUSION
Dhillion and Koch , 2004
12
Break point in the partner genes→simultaneous double stranded breaks.

13. RET/PTC EXPERIMENTAL PROOFS
• Undifferendiated thyroid or fetal thyroid tissue invitro-
irradiated-dose dependent direct induced
expression→abberant chimeric oncoprotein.1
• Microscopic foci of PTC- Precursor of fully metastatic form
of disease,,proven RET/PTC mRNA→RT-PCR.2
131. cardis, et al., 2006
2. Rabes, et al., 2000

14. BRAF
• Cytosolic protein
• Play role in regulating MAP Kinase/ERK
• Transduce mitogenic signal from cell membrane to
nucleus.
• Signalling Pathway effecting/normal function:
– cell division
– Differentiation
Grieco, et al., 1999 14

15. PTC: B-RAF MUTATION
(Sporadic)
1. Most common genetic change.
2. knock out experiment in mice- apoptotic death of
differentiated endothelial cells→embryonic lethality in utero
by E12.5
3. Point mutation
4. T→A inversion BRAFT1796A genetic change prevalance
36-39%
5. Valine→Glutamate BRAFV600E
5. Normal BRAF strucuture bipolar alligned site p loop
6. Mutated BRAF G596-V600 hydrophobic interaction with
G464-V471,, P loop not aligned to ATP.
15

16. BRAF CHROMOSOMAL REARRANGMENT
• All natural occuring cases-point mutation
• Activating reaarangement in BRAF radiation and sporadic
PTCs- constitutive active oncoprotein via paraceentric
chromosomal 7q inversion
• Fusion protein AKAP9-BRAF→kinase domain but no
autoinhibitory aminoterminal domain of BRAF.
• AKAP9-BRAF radiation cases 11%
• AKAP9-BRAF non radiation cases 0-1%
Prentice, et al., 1998 16

17. BRAF PROTEIN STRUCTURE
B-RAF PROTEIN DOMAIN STRUCTURE
Journel of clinical pathology
BRAFV6000E
SCIENCE DIRECT
17

18. SIGNALLING PATHWAY
MAPK PATHWAY
Kudo, 2011
Novus Biologicals
18
↓GDNF

19. SIGNALLING PATHWAY
MAPK PATHWAY
• Pathway elucidation,INVITRO STUDY:
– a. NIH3T3 cell line
– b. PC 12( rat pheochromochytoma)
• RET act via PI3K, MAPK for:
– a. Transformation
– b. Survival
– c. Migration
19Rouin, et al., 1995

20. GENES INVOLVEMENT IN OTHER CANCERS
RET INVOLVEMENT IN OTHER CANCERS 1
• Medullary thyroid carcinomas,
• Lung adenocarcinomas,
• Myeloproliferative disorders
BRAF INVOLVEMENT IN OTHER
CANCERS 2
• Melanoma,
• Colorectal cancer
• Other thyroid cancers.
201. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3839608/
2. ct.aacrjournals.org/content/10/3/385

21. CLINICAL STUDY
RESULTS
1. No overlap between PTC with
RET/PTC, BRAF, Or RAS
mutation.
2. 496 PTC,,Single mutation clue
for MAPK signalling mutation
→transformation to PTC.
3. PTC with BRAF
mutation→more aggresive
211. Alexander M.Castellano, 2014
2. THE CANCER GENOME ATLAS NETWORK, 2014

22. PTC: TREATMENT APPROACHES
1. CLINICAL APPROACH:
a. Radio Ioidne ablation
b. Long term supraphysiological dose of TSH to suppress
endogenous TSH production.
c. Invasive and metastatic pateints-less favourable prognosis
with radioiodine ablation therapy
d. Pharmocologic approch to block MAPK pathway.
2. GENETIC APPROACH:
Genetic engineering to induce inhibitors of MAPK pathway
effectors. 22Hamilton, et al., 1998

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