O papel dos C/EBPs no estômago. Diferenciação vs proliferação.

José Carlos Machado, Porto, Portugal

Aneuploidy# 3p, 7q, 13q (LOH)# 6q (LOH)# 1q, 5q, 17p (LOH)RAS (overexpression/mutation)ERBB-2 (amplification)TPR-MET (rearrangement)c-MET (6.0 Kb mARN)

p 53 (LOH, mutation)APC (LOH, mutation)DCC (LOH)EGF (overexpression)TGF-a (overexpression)TFF1 (loss of expression)

MSI (Microsatellite Instability)

S-Tn, T, S-TCDw75, S-LexLaminin, collagen IVu-PA, Cat-D NM 23 (loss)CD 44 (variants)

Diploidy# 3p, 7q, 13q (LOH)# 6q (LOH)

c-MET (6.0 Kb mRNA)

p 53 (LOH, mutation)

TGF-ß (overexpression)

K-SAM (amplification)

E-cadherin (loss/mutation)

S-Tn, T, S-TCDw75, S-Lex

NM 23 (loss)CD 44 (variants)

Intestinal carcinoma Diffuse carcinoma

Gastric gland

TFF1 expression in gastric carcinogenesis.

Machado JC et al. J Pathol 190: 437, 2000

C/EBPbeta

Ki67

Ki67 and C/EBP-β in normal gastric mucosa

Intestinal metaplasia Gastric dysplasia

C/EBPbeta expression

Intestinal atypical diffuseIntestinal Solid Diffuse

C/EBPbeta expression

C/EBP-β staining overlaps Ki67

C/EBP Ki67

C/EBPbeta mutation in a primary gastric carcinoma

Pro58Ala

Wild-type

Basic leucine zipper DNA-binding protein

C/EBP-β or NFIL6

TFF1 knockout mice developed adenomas and gastric cancer

Lefebvre O et al. Science 274: 259, 1996

C/EBPbeta and COX-2 co-expression in gastric carcinoma

COX2 C/EBPbeta Double IHC

C/EBP-β expression in GC cell lines

Luciferase assay showing the effect of C/EBPbeta transfection on COX-2 promoter activity

C/EBPα is expressed in gastric differentiated cells and co-localizes with TFF1

C/EBPα is under expressed in 34.6% of intestinal and atypical but not diffuse type carcinomas

non-neoplastic intestinal diffuse

A C/EBPα expression vector inhibits AGS cell proliferation

BRDU

Dapi

média

0

5

10

15

20

25

30

35

40

45

Mock 42KD

isoformas

% p

roli

fera

ção

média

C/EBPα modulates cell cycle proteins and is capable of up-regulating TFF1 expression

EGFRHER2/neu

IL6R/GP130

TGFBR

STAT3

Pi3K

Ras

SHP2

GSK3beta ERK

C/EBPbeta

Smad3

phosphorylationin

activ

atio

n

AKT

TFF1COX2

Candidate signalling pathways

C/EBPβ

C/EBPα

ciclinD1

p-ERK1/2

p-p38

tubulin

C/EBP stimulation with IL1B leads to phosphoeilation of ERK1/2 and p38

0 SB PD IL1b

IL1b+SB-p38

IL1b+PD

ERK

phospho-p38C/EBPβ Ki67

C/EBP co-localizes with phopho-p38

Conclusions C/EBPbeta is expressed in proliferative cells of the normal gastric

mucosa, and is overexpressed in intestinal metaplasia, dysplasia, and GC of the intestinal and atypical subtypes;

COX-2 is co-expressed with C/EBPbeta and can be regulated by this transcription factor;

C/EBPbeta may both be a marker of neoplastic transformation and play an active role in gastric tumourigenesis by regulating COX-2 expression;

C/EBPα is expressed in gastric foveolar differentiated cells and under-expressed in intestinal and atypical type tumours;

C/EBPα colocalizes with and up-regulates TFF1, and inhibits cell proliferation by changing the expression of cell cycle proteins in vitro.