The c-ret pathway and. K. Homicsko, Lucerne

Transcription

1 The c-ret pathway and biomarkers K. Homicsko, Lucerne

2 Origins 1. c-ret is a proto-oncogene on chromosome 10 (10q11.2) 2. «rearranged during transfection» 3. Synonyms: CDHF12, HSCR1, MEN2A, MEN2B, 3. Synonyms: CDHF12, HSCR1, MEN2A, MEN2B, MTC1, PTC, RET-ELE1, RET51, CCDS7200.1

3 First description (~10th oncogene) EcoRI HindIII BamHI C L H C L H C L 1. Transformed 3T3 fibroblast after transfection with DNA from lymphoma 2. Rearranged after transfection

4 Origins 1. c-ret is a proto-oncogene on chromosome 10 (10q11.2) 2. «rearranged during transfection» 3. Synonyms: CDHF12, HSCR1, MEN2A, MEN2B, MTC1, PTC, RET-ELE1, RET51, CCDS It is part of the cadherin superfamily and also receptor tyrosine kinase

5 Receptor dimerization => activation

6 Receptor tyrosine kinase

7 Receptor tyrosine kinase

8 Dimerisation and autophosphorylation

9 Origins 1. c-ret is a proto-oncogene on chromosome 10 (10q11.2) 2. «rearranged during transfection» 3. Synonyms: CDHF12, HSCR1, MEN2A, MEN2B, MTC1, PTC, RET-ELE1, RET51, CCDS It is part of the cadherin superfamily and also receptor tyrosine kinase 5. 3 alternatively spliced format occur: Ret51, Ret43 and Ret9

10 c-ret splice variants

11 Origins 1. c-ret is a proto-oncogene on chromosome 10 (10q11.2) 2. «rearranged during transfection» 3. Synonyms: CDHF12, HSCR1, MEN2A, MEN2B, MTC1, PTC, RET-ELE1, RET51, CCDS It is part of the cadherin superfamily and also receptor tyrosine kinase 5. 3 alternatively spliced format occur: Ret51, Ret43 and Ret9 6. Natural ligands are GDNP (glial cell line-derived neurotrophic factor) ligands

12 Natural ligands and co-receptors Ligands: 1. Glial cell-derived neurotrophic factor 2. Neurturin 3. Artemin 4. Persephin Co-receptors: 1. GFR1α1 2. GFR1α2 3. GFR1α3 4. GFR1α4

13 Ligands 1. GDNF: Pro-survival factor for dopaminergic cells (decrease in Parkinson s disease and amyotrophic lateralsclerosis, AML) 2. Neurturin: pro-survival of basal forebrain cholinergic neurons 3. Artemin: decreased levels in chronic pain syndromes 4. Persephin: basal forebrain cholinergic neurons (decreased levels in Alzheimer s disease) Re-expression of ligands could potentially be used in neurodegenerative diseases

14 Intracellular signaling

15 Downstream signaling 7. Inflammation

16 Adaptor protein binding

17 c-ret and cancer Mutations 1. Inactivating (Hirschsrpung s disease) 2. Activating (germ line 25%, sporadic 75%) Fusion gene families 1. RET/PTC 2. KIF5B-Ret (kinasin) 3. CDCC6-Ret (cell division cycle 6) Expression 1. c-ret 2. GDNF

18 Mutations

19 Medullary thyroid carcinoma 1. Sporadic: 25-60% c-ret mutations 1. Hereditary: ~99%

20 Hereditary c-ret-related cancer syndromes MEN2A fmtc MEN2A with cutaneous lichen amyloidosis MEN2A with Hirschscprung s disease MEN2B Corresponding tumor types: 1. Medullary thyroid carcinoma, pheocromocytoma, parathyroid hyperplasia/adenoma 2. Medullary thyroid carcinoma (MTC) 3. MEN2A and pruritic cutanous lesions over the upper back 4. MEN2A or fmtc with intestinal aganglionosis 5. MTC, pheocromocytoma, intestinal and mucosal ganglioneuromatosis, ocular abnormalities, marfanoid habitus

21 Activating mutations

22 Mutation/phenotype relationship 5 Exon Codon Cysteine-rich domain 10 Cys609, Cys611, Cys618,Cys 620 MEN2A, fmtc Transmembrane domain 11 Cys634Arg MEN2A (80%), fmtc fmtc fmtc 16 Met918Thr MEN2B (95%) Tyrosine kinase 1 Tyrosine kinase 2 3

23 Activation by cysteine mutations

24 Consequences of mutations in hereditary medullary thyroid cancer Mutations are grouped based on risk (Level1-3): Level1: Codons 609, 768, 790, 791, 804, and 891 metastatic fmtc > 5 year of age Level2: Codons 611, 618, 620, 634 metastatic fmtc < 5 year of age Level3: Codons 883, 918, 922, metastatic fmtc < 1 year of age Recommendations: Level1: wait until age of 10 then perform thyroidectomy or in case of rising calcitonin/cea Level2: thyroidectomy before the age of 5 years or in case of rising calcitonin/cea Level3: thyroidectomy within the first 6 months of life and preferably within the first month of life

25 Sporadic medullary thyroid cancer % of all thyroid cancer 2. Most frequent mutations ( Prognostic value of mutations in sporadic MTC: 1. Met918Thr mutant tumors show worst prognosis, more aggressive, more LN+, multifocal 2. No Ret mutations intermediate 3. Cysteine mutants: more indolent course BJC Vol. 100 No. 11. pp ,2009

26 Biomarkers Hereditary syndromes: pyrosequencing to determine surveillance/preventive attitude Sporadic mutations: the presence of mutations could drive treatment decisions Calcitonin/CEA levels Calcitonin testing with calcium or pentagastrin stimulation

27 Fusion genes

28 Papillary thyroid cancer genetics/c-ret Presence of RET/PTC varies between regions from 5% to 70% 12 rearranged forms both in sporadic and radiation induced PTC (postchernobyl up to 87% RET/H4 or RET/PTC3) Mutually exclusive with BRAFV600E mutations in PTC In familial PTC (fptc) c-ret rearrangements are present but causality is unclear RET/PTC fusion genes can be present in non-neoplastic Hashimoto s thyroiditis Other mutations are: ~40% BRAFV600E

29 RET/PTC fusion genes

30 FISH for RET/PTC British Journal of Cancer (2006) 94,

31 How to identify fusion genes?

32 Use whole genome RNA sequencing

33 KIF5B-RET 1.9% of all NSCLC adenocarcinomas

34 FISH for KIF5B-RET

35 Therapeutic consequences

36 cret mutations/fusion genes in other tumors

37 Over-expression of c-ret

38 Over-expression of GDNF

39 Compounds targeting c-ret/ret fusion genes

40 Conclusions Both c-ret and c-ret fusion genes are driver oncogenes of sporadic and hereditary tumors Determination of mutations and fusion genes could have consequences in both prevention and treatment Mutational analyzes and FISH are established and readily available Compounds targeting pathological c-ret activation show promise but require further studies and/or combinations