Loss of Rab25 promotes the development of intestinal neoplasia in mice and is associated with human colorectal adenocarcinomas.
Transformation of epithelial cells is associated with loss of cell polarity, which includes alterations in cell morphology as well as changes in the complement of plasma membrane proteins. Rab proteins regulate polarized trafficking to the cell membrane and therefore represent potential regulators of this neoplastic transition. Here we have demonstrated a tumor suppressor function for Rab25 in intestinal neoplasia in both mice and humans. Human colorectal adenocarcinomas exhibited reductions in Rab25 expression independent of stage, with lower Rab25 expression levels correlating with substantially shorter patient survival. In wild-type mice, Rab25 was strongly expressed in cells luminal to the proliferating cells of intestinal crypts. While Rab25-deficient mice did not exhibit gross pathology, ApcMin/+ mice crossed onto a Rab25-deficient background showed a 4-fold increase in intestinal polyps and a 2-fold increase in colonic tumors compared with parental ApcMin/+ mice. Rab25-deficient mice had decreased beta1 integrin staining in the lateral membranes of villus cells, and this pattern was accentuated in Rab25-deficient mice crossed onto the ApcMin/+ background. Additionally, Smad3+/- mice crossed onto a Rab25-deficient background demonstrated a marked increase in colonic tumor formation. Taken together, these results suggest that Rab25 may function as a tumor suppressor in intestinal epithelial cells through regulation of protein trafficking to the cell surface.
Nam
Ki Taek
KT
Nashville Department of Veterans Affairs Medical Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2733, USA.
Lee
Hyuk-Joon
HJ
Smith
J Joshua
JJ
Lapierre
Lynne A
LA
Kamath
Vidya P
VP
Chen
Xi
X
Aronow
Bruce J
BJ
Yeatman
Timothy J
TJ
Bhartur
Sheela G
SG
Calhoun
Benjamin C
BC
Condie
Brian
B
Manley
Nancy R
NR
Beauchamp
R Daniel
RD
Coffey
Robert J
RJ
Goldenring
James R
JR
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D019012:Integrin beta1 / Q000096:biosynthesis / Q000235:genetics; D007417:Intestinal Polyps / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009367:Neoplasm Staging; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D019012:Integrin beta1; C426009:LAMTOR2 protein, mouse; D011506:Proteins; C509763:Rab25 protein, human; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D025521:Tumor Suppressor Proteins; D020691:rab GTP-Binding Proteins