Ernesto Burgio

ISDE Italy

Scientific Committee

DOHAD

X rays

Metals

Viruses

CEM

Xenobiotics

EDCs

Environment���� Dynamic (Epi)-Genome

���� Neolamarckian Paradigm2

3

1

1

2

3

4

4

4

Fetal origins of adult diseases and cancer

….NON si tratta di una tematica di esclusiva pertinenza endocrinologica…e/opediatrica

Organismo umano: clone cellulare derivato da un’unica cellula totipotente (zigote) e

costituito da miliardi di cellule con unico DNA

e differente (epi)genoma

Parole chiaveEDCs

DOHAD

Fetal Programming

Fluid (Epi-Genome)

Finestre di Esposizione

Cellule totipotenti…multipotenti…

Differenziazione

cellulare

Plasticità

potenzialità

MASSIMA

Gli interferenti endocrini sono sostanze mimetiche o comunque in grado di interferire sul cell signaling intercellulare e intracellulare a vario livello: comunicazione intercellulare (discorso analogo potrebbe esser fatto per gli antibiotici tra gli organismi monocellulari), sui recettori membranari e nucleari, sulle pathways di trasduzione dei segnali dalla membrana al nucleo, sui meccanismi di trascrizione, traduzione etc. Gli effetti più significativi sono connessi alla possibile loro azione su cellule/tessuti di organismi in via di sviluppo, con particolare rilievo per specifiche fasi di sviluppo di organi e tessuti (finestre di esposizione). Il problema fondamentale (in ambito biomedico) connesso alla diffusione in ambiente (catene alimentari !) di molecole xenobiotiche, metalli pesanti ecc.. in grado di agire da interferenti endocrini (perturbatori informatici) può essere riassunto in una sigla: DOHAD

12

3

4

Fetal Programming

Differentiation

Organismo adulto = Clone di 100mila miliardi di cellule derivanti da uno zigote: tutte uguali sul piano genetico differenti sul piano epi-genetico e morfofunzionale

In developmental biology, cellular differentiation is the process by which a less

specialized cell becomes a more specialized

cell type. Differentiation occurs numerous times during the development of a multicellular organism as the organism

changes from a single zygote to a complex system of tissues and cell types. Differentiation is a common process in adults as well: adult stem cells divide and create fully-differentiated daughter cells during

tissue repair and during normal cell turnover. Cell differentiation causes its size, shape, polarity, metabolic activity, and

responsiveness to signals to change

dramatically.

These changes are largely due to highly-controlled modifications in gene expression. With a few exceptions, cellular differentiation almost never involves a change in the DNA sequence itself. Thus, different cells can have very different physical characteristics despite having the same genome.

Cellular differentiation during development can be understood as the result of a gene regulatory network. A regulatory gene and its cis-regulatory modules are nodes in a gene regulatory network; they receive

input and create output elsewhere in the

network . The systems biology approach to developmental biology emphasizes the importance of investigating how developmental

mechanisms interact to produce predictable patterns (morphogenesis).

A

B

Cellular Differentiation: an Epigentic process

A

TCDD

Viruses

HERVs

CEM

3

2

1

SYNERGISM ?!

“FLUID EPI-GENOME”

4

Dovremmo rappresentare l’”ambiente “ come un flusso

continuo di informazioni semplici - i fotoni: singoli pacchetti di E = M = Informazione - o complesse (molecole organiche …virus… etc..) in grado di interagire con le cellule (recettori

membranari � proteine di trasduzione � (epi)-genoma…

Everyday levels matterEveryday levels matter

At truly low levels At truly low levels ……

it interferes with it interferes with

gene activationgene activation

At high levels… arsenic kills people

At moderately low levels…it causes a range of diseases

KaltreiderKaltreider et alet al. 2002. 2002

The Epigenetic Players

DNAMethylation

Histonemodification

ChromatinRemodelingmachinery

+

ON OFF

Euchromatin

Heterochromatin

Epigenetics is defined as mitotically and meiotically heritable changes in gene expression that do not involve a change in

the DNA sequence…. DNA methylation and histone modifications are known to have profound effects on controlling gene

expression.. MicroRNAs (miRNAs) are small RNA molecules, _22 nucleotides long that can negatively control their target

gene expression posttranscriptionally

Fraga et al., PNAS. 2005.

1

4

32

MicroRNAs

Chuang JC, Jones PA Epigenetics and MicroRNAs Pediatr Res 2007; 61: 24R–29R

Histone Tails

are subject to a variety of covalent

modifications

Histone Code”hypothesis: modifications

of the Histone tails

act as marks read

by other proteins

to control the expression

or replication of chromosomal regions

E.g. generally, Histone Acetylation

is associated with

transcriptionally

active genes

Deacetylation

is associated with inactive genes

(= gene silencing)

Mismatch Repair EnzymesTrascription Factors

Hormones

Correct organizationof chromatin

Gene- and tissue-specific epigenetic patterns

Silencing repetitive elements

Genomicimprinting

X chromosomeinactivation

Controlling active and inactive states of embryonic and somatic cells

1

2

ab

c

d

e

f

3 microRNAs

Once thought to play only a structural role, it now

appears that chromatin plays a key regulatory role by

marshalling access to the DNA template…

…chromatin itself is the direct target of many toxicants *

… toxicant-induced perturbations in chromatin structure

may precipitate adverse effects (* Heavy metals, EDCs..)forcing genome to change

Nuclear ReceptorDNA Response Element

Histone

Lysine

Acetylation

Histone Deacetylases.

Histone Acetyltransferases;

Histone Methyltransferases

ATP-dependent Nucleosome

Remodeling Complex

Many toxicants cause rapid alterations in gene expression by activating

protein kinase signaling

cascades.

The resulting rapid,

defensive alterations in

gene activity require the

transmission of a signal

directly to the histones

present in the chromatin

of stress response genes:

within minutes

of exposurethe phosphorylation of

serine 10 of histone H3

and the acetylation

of lysines 9 and/or 14

take place

H3-K9 H3-S10

P

These modifications are believed to be

essential for the full transcriptional response to

stress-inducing chemicals

http://www.ewg.org/reports/generations/

CHEMICAL FALL OUT

UParticlesHeavy MetalsEDCs (Dioxines like molecules), PCBs,

Bisphenol A, Phtalates1 2 3

The gift our mothersnever wanted to give us

XXI century: a dramatic transformation of the

environment and uterine microenvironment

The main problem that the myriad sources of pollution across the planet is likely to causeto our health and to future generations is indeed the load of toxic molecules many of which

are incidental products of incomplete combustion.. accumulated in our bodies: EPA

(Environmental Protection Agency); US Centers for Disease Control and Prevention; Environmental

Working Group (EWG) (an environmental organization specialized in environmental research)are systematically biomonitoring the body burden of toxic chemical compounds, elements,

or their metabolites (Chemical Body Burden), in biological substances since many years

À présent de nombreuses études, en différentes pays, cherchent d'évaluer la charge chimique du corps (chemical body burden) .. surtout chez les femmes, les enfants, les embryons/foetus, fournissant des résultats dramatiques. Parmi les plus connus sont les études réalisées par des chercheurs de l'Environmental Working

Group, qui ont documenté la présence de centaines de substances toxiques, mutagènes et cancérigènes dans le sang, l'urine, le lait maternel, le sang de cordon: inquiétude a suscité une étude qui documenté la présence de substances (géno) toxiques et mutagènes dans tous les cordons ombilicaux testées, démontrant l'omniprésence et la précocité de l'exposition fœtale

Epigenetic perturbations early in life

Epigenetics and human disease

Viruses

Chemicals

X Rays, UP..

First Hit (s) Second Hit (s)…

Genetic Damages

Fetal Programming (Epigenetic)

E’ possibile ipotizzare/dimostrare che le modifiche dell'assetto epigenetico si trasformino progressivamente in modifiche

genetiche e/o cariotipiche … e che, nella misura in cui coinvolgono i gameti possano trasmettersi di generazione in

generazione ecc..

Insulino-resistance

Diabetes

Cardiovascular Diseases

the XX Century Epidemic Revolution

Barker Hypothesis (1989)

(1989)

ab

c

We may even hypothesize that a lot of diseases characterizing what we may call the XX Century Epidemic

Revolution

[the epidemic change we are witnessing all over the world, and especially in the most developed countries, concerning a switch from a prevalence of acute exogenous

(infectious and parasitic) to a prevalence of chronic endogenous (immuno-mediate, neurodegenerative, neuro-endocrine, cardiovascular and neoplastic) diseases, - atopy/asthma and autoimmune disorders (diabetes I, celiac disease etc); obesity, metabolic syndrome, diabetes II; atherosclerosis (stroke, infarct etc); Alzheimer Disease, Parkinson Disease; Cancer] is a late result, in adults, of a developmental process gone awry, deeply rooted in the first stages of

embryo-fetal development

• Perchè la celiachia (glutine + DQ2-DQ8 + Permeabilità

Intestinale + Gut Ecosystem/TLRs) ha un incremento

di circa il 10% annuo in Italia..?

• Perché asthma/allergie di I tipo GC sono passate da una prevalenza dell'1% a 25-30% in meno di un secolo (allergens + genes + flogosis/remodeling) ecc..

• Che legame c'è tra l’incremento epidemico di obesità.. sindrome metabolica.. diabete II.. aterosclerosi e

patol.cardiovascolari (genes+epigenetics/phlogosis + TLRs)

• ENVIRONMENT HEALTH

• Genome and Epi-genome

• The Epidemic Revolution of XXth Century

• 3 PARADIGMSBarker HypothesisHygiene HypothesisSystemic-chronic (low grade) Inflammation

• Back to the NEO-LAMARCKIAN PARADIGM ENVIRONMENT � Epigenetic Changes

���� Fetal Programming

Fluid (Epi)genome

1

2

3

HSPs

Activation

HSPs/petidesDanger Theory

(Auto)Immunity

Autoinflammation

ROS

The Epidemic Revolution

Of the XX century

Environment

mRNAs

fluid (epi)genome

developmental

plasticity

Pharmaceuticals,

pesticides,

air pollutants,

industrial chemicals,

heavy metals,

hormones,

nutrition,

and behavior

can change

gene expression

through a broad array of

gene regulatory

mechanisms..

highlighting the potential

role for altered

DNA methylation

in fetal origins

of adult disease

and inheritance

of acquired

genetic changes

Les origines embryo-fœtales du cancer : cancérogénèse

transplacentaire et transgénérationnelle

Ernesto Burgio

ISDE Italy

Scientific Committee

DOHAD

X rays

Metals

Viruses

CEM

Xenobiotics

EDCs

Environment���� Dynamic (Epi)-Genome

���� Neolamarckian Paradigm

2

3

1

1

2

3

4

4

4

Incidenza di tumori (anno/100.000) Incidenza di tumori (anno/100.000)

Poumon 80

60

40

20

4

2

1,5

Sein

Colon

EstomacLymphôme

10

LeucLeucéémie mie

lymphatilymphati

quequeLeucLeucéémie mie lymphatiquelymphatique

Encéphale

Lymphômes

Neuroblastoma-Retinoblastoma1

<1 Tessuti molli, rene (Wilms), gonadi

5

ReinCerveau

In genere si afferma che i

tumori infantili sono una

patologia rara. Bisogna però

intendersi. E’ opportuno

ricordare come, in termini

assoluti, di cancro si ammali

un bambino su 5-600 e che

oltre 13 mila bambini si

ammalano ogni anno di

cancro nei soli USA; come

nonostante i significativi

miglioramenti prognostici

degli ultimi decenni il cancro

rappresenti la prima

causa di morte per malattia

In età pediatrica ; come

anche in questa fascia

d’età, da 40 anni a questa

parte, si assista in tutto il

mondo a un incremento

significativo e continuo

della patologia tumorale

Bleyer A, O’Leary M, Barr R, Ries LA,

editors. Cancer epidemiology in older

adolescents and young adults 15-29

ears of age, including SEER incidence

and survival: 1975-2000. NIH Pub. No.

06-5767. Bethesda (MD): National

Cancer Institute; 2006. Jemal A, Siegel

R, Ward E, et al. Cancer statistics,

2008. CA Cancer J Clin 2008;58:71 – 6.

Alberto Tommasini,

Laboratorio Immunologia

Pediatrica, IRCCS

Burlo Garofolo

Le CA est le facteur principal de décès

par maladie dans l'enfance et l’on assiste à une augmentation

importante et constante des tumeurs

dans le monde pour ce groupe d'age

…. une accumulation des lésions oxydantes au niveau du ADN

…. une amélioration de la qualité du diagnostic

L’on oublie trop souvent que l’augmentation du nombre

de cancers touche toutes les tranches d’âge…... et, surtout, qu’il y a une augmentation très importante des cancers chez les enfants.

INCIDENZA DI INCIDENZA DI NEOPLASIE in INFANZIA E ADOLESCENZANEOPLASIE in INFANZIA E ADOLESCENZA IN IN EUROPA (anni 1970EUROPA (anni 1970--1999)1999)

mother

latency

Un primo report del progetto, pubblicato su Lancet nel 2004, evidenziò un incremento

annuo dell’1-1,5 % per tutte le neoplasie (con aumenti più marcati per linfomi, sarcomi dei tessuti molli, tumori delle cellule germinali e del sistema nervoso).

.. come risulta chiaramente dal recente progetto ACCIS (Automated Childhood Cancer Information System) - un ampio monitoraggio condotto da una

squadra di epidemiologi IARC su 63 registri oncologici di 19 paesi europei, per un totale di oltre 130 mila tumori di tutti i tipi (113 mila pediatrici e 18 mila di età adolescenziale)

Steliarova-Foucher E, Stiller C, Kaatsch P, Berrino F, CoeberghJW, Lacour B, Parkin M. Geographical patterns and time trends

of cancer incidence and survival among children and

adolescents in Europe since the 1970s (the ACCISproject): an

epidemiological study. Lancet. 2004 Dec 11-17;364(9451):2097-105

http://www-dep.iarc.fr/accis.htm

Miglioramenti diagnostici !?

Ucraina, Bielorussia ?!

I dati del progetto ACCIS pubblicati su Lancet furono ben presto confermati dalla successiva rassegna (la più completa a tutt’oggi) dei dati emersi dallo studio, che costituisce ormai il più ampio database europeo sul cancro, pubblicata due anni dopo, in un numero monografico, dall’European Journal of Cancer: 18 articoli in tutto, che contengono l’analisi dettagliata dei dati sui tassi di incidenza e sui trends di prevalenza

e sopravvivenza…

E’ sufficiente sottolineare come in 20 anni (tra il 1978 e il 1997) si sia assistito, in Europa, ad un incremento

medio generale di neoplasie ad insorgenza in età

pediatrica dell’1,1% annuo

(ma del 2% annuo circa nel

primo anno

di vità e dell’1,3% in età

adolescenziale).

Increased risk was obtained for both

cellular and cordless phones, highest in the

group with >10 years latency period.

… se possibile ancora peggiori sono le notizie per i bambini italiani. I recenti dati del Rapporto AIRTUM

(Associazione Italiana Registri

Tumori) 2008 sui tumori infantili , dimostrano infatti come i dati di

incidenza e gli andamenti

temporali siano in Italia peggiori

che negli altri paesi europei e negli

USA (il che, sia detto per inciso, priva di qualsiasi valore l’ipotetico fattore “miglioramento diagnostico”).

Rapporto AIRTUM 2008 - Tumori infantili.

Incidenza, sopravvivenza,

andamenti temporali Epidemiologia & Prevenzione 2008; 32(3) Suppl 2: 1-112

• L’incremento più consistente riguarda i bimbi sotto l’anno di età (+ 3,2%), seguiti da quelli tra 10 e 14 anni (+2,4%), mentre è simile negli altri due gruppi (+1,6% nella fascia di età1-4 anni, +1,8% tra i 5 e i 9 anni).

• I tre tumori più frequenti nei bambini sono tutti in aumento:• leucemie + 1,6% annuo; linfomi + 4,6% annuo; tumori del sistema

nervoso centrale + 2,0% annuo• Un fenomeno simile è stato osservato in diversi Paesi,

• ma… in Italia il cambiamento percentuale annuo risulta più alto che in Europa:per l’insieme di tutti i tumori (+2% vs 1,1%)per le leucemie (+1,6% vs 0,6%)per i tumori del sistema nervoso centrale (+2% vs 1,7%) per i linfomi (+4,6% vs 0,9%).

• (Negli Stati Uniti il tasso per tutti i tumori non è aumentato in modo significativo (+0,6%), l’incremento delle leucemie è dello 0,4% e i tumori del SNC sono stabili (-0,1%))

On ne peut pas expliquer tout cela par l’accumulation des lésions oxydantes comme chez les sujets plus âgés. De plus, cette augmentation touche tout particulièrement les enfants dans leur première

année de vie (le taux de l'incidence a augmenté de >2% dans le première année; de 1,3% pendant l'adolescence)

Prenatal origin of certain childhood leukaemias

Le processus de cancérogénèse est généralement très long…

Donc, le véritable problème est l’exposition des parents (gamètes) aux facteurs de risque.

Le processus de cancérogénèse a débuté bien avant la naissance de l’enfant *.

On peut aussi dire que la phase d’initiation *

tumorale (1° Hit de Knudson) survient lors

du développement ontogénétique du fœtus

1

Trasmissione transgenerazionale 2

Alterazione memoria epigenetica-gameti

3

Il n’y a que deux possibilités:1) l’exposition du fœtus à des agents physiques (X-rays), chimiques ou biologiques (virus)

(transmis par transmission trans-placentaire ) qui puissent endamager directement le foetus 2) la transmission trans-generationelle d’une ou plusieurs lesions genètiques ou epi-génetiques

Cheryl Lyn Walker UT MD Anderson Cancer Center

Ce sont des quantités minimales de molécules (epi)génotoxiques, induisant des transformations continuelles de la chromatine, qui constituent le véritable problème. C’est un processus très lent pouvant démarrer lors des premières

étapes du développement fœtal. Et, même dans les gamètes. Si les tissus du fœtus sont mal programmés au début et s’il y a un stress épigénétique

progressif, les mutations génétiques et chromosomiques vont davantage se produire

Herewe are

Cancro Malattia genetica ? Sì o piuttosto: dapprima epi-

genetica e infine genetica come praticamente tutte le

malattie croniche (flogistico-degenerative)…

Si le cancer est le produit de plusieurs

mutations stocastiques (SMT)…

.. pourqoui faudrait’il se produire cette

augmentation progressive

d’accidents génetiques ?!

Tout ça paraît raisonable… Mais le veritable problème est:

pourquoi cette augmentation continuelle et progressive ?!

Alterations in three types of genes are responsible for tumorigenesis: oncogenes, tumor-suppressor genes and stability genes

Unlike diseases such as cystic fibrosis or muscular dystrophy, wherein mutations in one gene can cause disease, no single gene defect'causes' cancer. Mammalian cells have multiple safeguards to protect them

against the potentially lethal effects of cancer gene mutations, and only when several genes are defective does an invasive cancer develop

The revolution in cancer research can be summed up

in a single sentence: cancer is, in essence, a genetic disease

STEP 1 La delezione o la mutazione del gene APC in 5q21 è sufficiente perché il colon venga tappezzato di polipi adenomatosi; Il DNA

diventa ipometilato ⇒⇒⇒⇒nuove mutazioni

STEP 2 Le mutazioni di K-RAS (K-RAS1 in 6p12-11 e K-RAS2

in 12p12) sono spesso coinvolte nella progressione degli adenomi da precoci a intermedi.

STEP 3 Il presunto gene soppressore dei tumori coinvolto è DCC (“Deleted in Colon Cancer” → perdita di eterozigosi in 18q21.3).

STEP 4 mutazioni gene oncosoppressore

p53 (localizzato in 17p12-13).

STEP 5 MutazionI del gene NM23-H1 (17q22)

rendono il CA altamente invasivo/metastatico..

Darwinian Evolution Through Random Mutation

BC Genetics

BRCA1

BRCA2

CHEK2

HMMR

TP53

Somaticmutations

that can lead to breast cancer have been experimentally linked to estrogen exposure

… HMMR gene, encoding a centrosome subunit, interacts with the

well-known breast cancer gene BRCA1 ...

In contrast to the somatic mutation theory, the TOFT postulates that: (i) carcinogenesis represents a problem of tissue organization,

(ii) proliferation is the default state of all cells, and (iii) carcinogenesis is a reversible phenomenon

DOHAD

Le cancer est bien plutôt un processus d’évolution raté, qui à ses originesdans les premiéres phases du dévelopment fœtal (fetal programming)

Tumors are complex tissues in which mutant cancer cells

have conscripted and subverted normal cell types

to serve as active collaborators in their neoplastic agenda

… un processus d’évolution imparfaite qui produit un petit organe doué d’une vascularisation propre, d’un stroma (un tissu de soutien), d’un veritable système immunitaire constitué de macrophages activés(liens entre inflammation et cancer).

1) TAMs secrete a variety of proteases to breakdown the basement membrane

2) macrophages cooperate with tumor cells to induce

a vascular supply

3) Macrophagesin hypoxic areassecrete factors

that suppress

the antitumor

functions of immune effectors

4)���� metastasis: a subpopulation of TAMs associated with tumor vesselssecretes factors like EGF to guide tumor cells in the stroma toward blood vessels

Our findingssuggest thatmicrovascular

endothelial cells in

B-cell lymphomas

are in parttumor-related

…. les mêmes mutations génétiques et

chromosomiques, d’ailleurs toujours

assez complexes (aneuploïdie,

translocations, mutations des oncogènes et des gènes suppresseurs) se trouvent dans plusieurs tissus intéressés

Istituto Superiore di Sanità 3 11 08 - Giornata in ricordo di Lorenzo Tomatis

CANCRO:Il paradigma epigenetico

Ernesto Burgio

Comitato ScientificoISDE Italia

Cancerogenesi ambientaleIl contributo della scienza medica alla

risoluzione dei problemi di inquinamento ambientale

1

2

3

2

Ce qui se passe, au début, ce n’est que des modifications épigénétiques produites par un stress prolongé du tissu et du génôme :

une hypométhylation de séquence d’ADN et une hypeméthylation spécifique des promoteurs des gènes suppresseurs...

We have now analyzed a series of promoter

hypermethylation changes in 12 genes.. each rigorously characterized for association with abnormal gene silencing in cancer…

Our results provide an unusual view

of the pervasiveness of DNA alterations, in

this case an epigenetic change, in human

cancer and a powerful set of markers to

outline the disruption of critical pathways in

tumorigenesis

Conclusions

Our data demonstrate, using a candidate gene approach, that promoter hypermethylation

of 12 genes involving important cellular pathways

in tumorigenesis is a feature of each of 15 major

human tumor types studied. Moreover, although many tumors share this change for a given gene, unique profiles do exist

for the tumor types.

In the present study, we demonstrate how one single type of DNA alteration,

aberrant methylation of gene

promoters, can point to pathways

disrupted in every type of cancer and can provide markers

for sensitive detection of virtually

all tumor types.

ONE OR MORE OF THE GENES STUDIED IS HYPERMETHYLATED IN EVERY TUMOR TYPE. HOWEVER, THE PROFILE

OF PROMOTER HYPERMETHYLATION FOR THE GENES DIFFERS FOR EACH CANCER TYPE, PROVIDING A TUMOR-

TYPE AND GENE-SPECIFIC PROFILE. SOME GENES, SUCH AS THE CELL CYCLE INHIBITOR P16INK4A, ARE

HYPERMETHYLATED ACROSS MANY TUMOR TYPES INCLUDING COLORECTAL, LUNG, AND BREAST CARCINOMAS

Other changes, such as for the DNA repair gene MGMT and DAPK, also have a wide

distribution

These mechanisms may be activated in cells by

continuing proliferative

and survival signaling

in a sustained stress

environment (SSE)…

longterm exposure

to this signaling epigenetically

reprograms the genome

of some cells..

.. finalement, ce processus n’est pas fondamentalement de nature

stochastique… mais réactif-adaptatif

Mutations match epigenetic tags

Selection of Mutants follows !

Many epigenetic tags are Induced in stem cells duringfetal programming

tags = marcature

.. cells with the properties of stem cells are integral to

the development and perpetuation of several forms of human cancer

Stem cells have three distinctive properties: selfrenewal (i.e., at cell division, one or both daughter cells retain the same biologic properties as the parent cell), the capability to develop into

multiple lineages, and the potential to proliferate

extensively..

Aberrantly increased

self-renewal, in combination with the intrinsic growth

potential of stem cells, may account for much of what is considered a malignant phenotype..

Julius Cohnheim.. in 1867 proposed that tumors derived not from normal adult tissues, but from “embryonal cell rests”,

Model for carcinogenesis resulting from persistence of a state of injury repair.

1

2autonomous Wnt or Hh signalling

Further genetic or epigenetic change in such a persistently activated stem cell might produce a cancer

stem cell.. aggressively propagating a CA

3

3

http://science.nasa.gov/headlines/y2006/images/telomeres/caps_med.jpg

Telomere_caps.gif� (600 × 471 pixels, file size: 61 KB, MIME type: image/gif)

Nota EVO DEVO:

l’attivazione tanto dei C-ONC.. quanto della telomerasi rappresenta il ritorno a un assetto proprio del periodo embrio-fetale.. allorché telomerasi e “proto-oncogeni (geni importanti nelle pathways di proliferazione e differenziazione cellulare) sono particolarmente attivi.

Potter demonstrated the presence of embryonal biochemical markers in mouse and human hepatomasleading him to conclude that hepatoma cells are arrested in their development and this differentiation

block may contribute to tumor formation: “oncogeny is blocked ontogeny”

The hypothesis developed in this article is that chronic

stressors can induce adaptive

rearrangements

of the genome which might result in new proteins helping

survival in a harmful

environment or trigger the

development of a completely

‘‘new’’ organ – the cancer –which also survives – even though its survival is at the

expenses of its host.

Stressors, which cannot be compensated for with the usual cell possibilities might arouse evolutionary mechanisms

intended to create new protein variants. One of these is the activation of transposable elements which leads to a reformatting of the genome.

1

2

1

3

Transposable elements can be seen as a natural genetic engineering system

capable of acting not just on one location at a time but on the genome as a whole ..This dynamic view of the genome has been illustrated most impressively by Shapiro who stated that the genome is composed of modular units arranged

in a “Lego-like” manner that can be altered under certain circumstances

THE CAUSE OF CHROMOSOMAL

ABNORMALITIES REMAINS POORLY UNDERSTOOD.

STUDIES OF VARIOUS TYPES OF LEUKEMIA

HAVE SHOWN THAT CERTAIN

ENVIRONMENTAL AND

OCCUPATIONAL

EXPOSURES AND THERAPY WITH

CYTOTOXIC DRUGS CAN INDUCE

CHROMOSOMAL ABERRATIONS. FOR EXAMPLE, CASES OF MYELODYSPLASTIC

SYNDROME OR AML

THAT ARISE AFTER TREATMENT WITH ALKYLATING AGENTS ARE FREQUENTLY

ASSOCIATED WITHUNBALANCED ABNORMALITIES,

PRIMARILY DELETION OR LOSS OF

CHROMOSOME 5 OR 7 (OR BOTH),

…WHEREAS THERAPY WITH TOPOISOMERASE II INHIBITORS IS

TYPICALLY ASSOCIATED WITH BALANCED

ABNORMALITIES, MOST COMMONLY TRANSLOCATIONS

INVOLVING THE MLL GENE ON

CHROMOSOME

BAND 11Q23.1

Are TRANSLOCATIONS chromosomal aberrations or reactive/positive rearrangements ??

THE FIRST EVIDENCE THAT CANCER ARISES FROM SOMATIC GENETIC

ALTERATIONS CAME FROM STUDIES OF BURKITT'S LYMPHOMA, IN WHICH

ONE OF THREE DIFFERENT

TRANSLOCATIONS JUXTAPOSES AN ONCOGENE, MYC, ON CHROMOSOME

8q24

TO ONE OF THE LOCI FOR

IMMUNOGLOBULIN GENES. CHROMOSOMES 14q, 22q, AND 2q

— THE TRANSLOCATION PARTNERS —

EACH CARRIES ENHANCER

ELEMENTS IN THE

IMMUNOGLOBULIN LOCI,

THEREBY ACTIVATING THE

JUXTAPOSED C-MYC

ONCOGENE

Croce CM. Oncogenes and Cancer. N Engl J Med 2008;358:502-11.

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+

Are the antibody gene loci

quite“dangerous places” for

proto-oncogenes to take up residence ?

IN THE CANCEROUS B CELLS, THE PORTION OF CHROMOSOME 18 CONTAINING THE BCL-2 LOCUS HAS UNDERGONE A RECIPROCAL TRANSLOCATION WITH THE PORTION OF CHROMOSOME 14 CONTAINING THE ANTIBODY HEAVY CHAIN

LOCUS. THIS T(14;18) TRANSLOCATION PLACES THE BCL-2 GENE CLOSE TO THE HEAVY CHAIN GENE ENHANCER.

H Chain-enhancer is very active in B cells...

Figure 1. Agricultural exposure drives a dramatic increase of t(14;18)+ clones in blood

Agopian et al. Journal of Experimental Medicine 2009:206:1473-

1483

© 2009 Agopian et.al.

Evolution of t(14;18) frequency in PBMCsfrom control and exposed populations

For each individual, independent BCL2/JH

clones are pictured in distinct shades

Clonality analysis

Figure 2. t(14;18)+ cells in HI are actively transcribing BCL2 from the translocated allele

Agopian et al. Journal of Experimental Medicine 2009:206:1473-

1483

© 2009 Agopian et.al.

... il gene bcl 2 è espresso nella zona follicolare .. ha un ruolo fisiologico

importante: blocca

l’apoptosi nei cloni linfocitari destinati a diventare cellule di

memoria. ma può essere

attivato anche in cellule della corticale mediante diversi meccanismi: il principale è la traslocazione t14:18.. che può porre il gene sotto il controllo del promoter

delle Ig o del TCR

in altri casi di linfoma follicolare il gene espresso in modo

eccessivo (���� anti-apoptosi) è il Bcl 6..

Exposure to NHL-associated carcinogens,such as dioxin or pesticides, may cause

expansion of t(14;18)-positive clones.

Translocations typical of myeloid leukaemia, probably due to maternal exposure to some toxic compound, were shown to be present at birth in children who developed the disease years later (while not sufficient per se to cause the disease, they might

increase the risk for leukaemia by inducing genomic instability) Tomatis L. Identification of carcinogenic agents and primary

prevention of cancer. Ann N Y Acad Sci. 2006 Sep;1076:1-14

Translocation involving band

11q23 in AML may occur as a result of a deletion or trans-

locations

with a number of otherchromosomes and is usuallyassociatedwith M4 or M5 and a poor prognosis

Nakamura T, Mori T, Tada S, et al. ALL-1 is a histone methyltransferase that

assembles a supercomplex of proteins involved in transcriptional regulation

Cell 2002;10:1119-1128.

IN ALL AND AML, THE ALL1

(ALSO NAMED MLL) GENE CAN FUSE WITH 1 OF MORE

THAN 50 GENES. ALL1 IS

PART OF A MULTIPROTEIN

COMPLEX. MOST OF THE PROTEINS IN THE COMPLEX ARE COMPONENTS OF TRANSCRIPTION

COMPLEXES; OTHERS ARE INVOLVED IN HISTONE

METHYLATION AND RNA

PROCESSING. THE ENTIRE COMPLEX REMODELS,

ACETYLATES, DEACETYLATES,

AND METHYLATES

NUCLEOSOMES ANDHISTONES. THE FUSION OF

ALL1 WITH 1 OF these 50

PROTEINS RESULTS IN THE FORMATION OF THE

CHIMERIC PROTEINS THAT UNDERLIE ALL AND AML.

ALL1 (MLL) FUSION PROTEINS

DEREGULATE HOMEOBOX

GENES (WHICH ENCODE TRANSCRIPTIONS FACTORS)..AND MICRORNA

GENES SUCH AS MIR191.

AF9 Location 9p22

MLL * Location 11q23

*

Several lines of evidence point to a mishap in non-homologous end joining of double strand breaks as the most likely reason for 11q23 translocations.

The first and most striking property of MLL fusion proteins is their incredible diversity. Mbeen found in 73 different translocations and 54 partner genes have been cloned (http://atlasgeneticsoncology.org/Genes/MLL.html).

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Diethylstilbestrol

God does not play dice È la celebre affermazione che suggella l'acceso dibattito tra Einstein e i sostenitori di una certa interpretazione della fisica quantistica…

God is subtle but not malicious

I believe in Spinoza's God who reveals himself in the orderly harmony of what exists

“A clever man solves a problem, a wise man avoids it”

‘‘We can’t solve problems by using the same kind of thinking we used when we created them’’