Trefoil factor family-1 mutations enhance gastric cancer cell invasion through distinct signaling pathways.
OBJECTIVE
Trefoil factor family-1 (TFF1) is a key gastric tumor-suppressor gene. TFF1 knockout mice develop multiple gastric adenomas and carcinomas, and human gastric cancers typically lack TFF1 expression. Recently, TFF1 mutations have been found in human gastric cancer. The purpose of this study was to determine the functionality of these mutants.


METHODS
Recombinant wild-type TFF1 and the gastric cancer-associated TFF1 mutants (A10D and E13K) were produced and tested for their effect on gastric cancer cell proliferation, apoptosis, and invasion. Molecular modeling was used to guide the choice of mutants and to evaluate structure-function relationships.


RESULTS
Molecular modeling suggested that A10D and E13K altered the surface charge of the loop 1 region of TFF1 without disturbing protein stability. Recombinant wild-type TFF1 significantly inhibited cell growth; A10D and E13K lost this tumor-suppressive property along with the ability to block etoposide-induced apoptosis. Although wild-type TFF1 promoted cell invasion, A10D and E13K were even more pro-invasive. Invasion induced by both mutants was blocked by inhibiting PI3-kinase or phospholipase-C, but inhibiting Rho-associated kinase (ROCK) blocked only E13K-induced invasion.


CONCLUSIONS
The loss of tumor-suppressor activity and gain of invasiveness from single point mutations constitute evidence for a functional role of TFF1 mutations in gastric cancer. These site-directed mutagenesis experiments provide the tools for continued probing of signal transduction mechanisms and structural elements responsible for TFF1 functions.
Yio
Xianyang
X
Division of Gastroenterology, Department of Medicine, Mount Sinai School of Medicine, New York, New York, USA.
Diamond
Matthew
M
Zhang
Jie-Yu
JY
Weinstein
Harel
H
Wang
Lu-Hai
LH
Werther
Lawrence
L
Itzkowitz
Steven
S
D017209:Apoptosis / Q000235:genetics*; D001483:Base Sequence; D015153:Blotting, Western; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D009361:Neoplasm Invasiveness / Q000235:genetics* / Q000473:pathology; D016133:Polymerase Chain Reaction; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D015398:Signal Transduction; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology; D000071163:Trefoil Factor-1; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics*
C051838:TFF1 protein, human; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins