Fax: (203) 737-4067
Microsatellite instability and gene mutations in transforming growth factor-beta type II receptor are absent in small bowel carcinoid tumors
Article first published online: 14 DEC 2004
Copyright © 2004 American Cancer Society
Volume 103, Issue 2, pages 229–236, 15 January 2005
How to Cite
Kidd, M., Eick, G., Shapiro, M. D., Camp, R. L., Mane, S. M. and Modlin, I. M. (2005), Microsatellite instability and gene mutations in transforming growth factor-beta type II receptor are absent in small bowel carcinoid tumors. Cancer, 103: 229–236. doi: 10.1002/cncr.20750
- Issue published online: 5 JAN 2005
- Article first published online: 14 DEC 2004
- Manuscript Revised: 20 SEP 2004
- Manuscript Accepted: 20 SEP 2004
- Manuscript Received: 31 MAY 2004
- microsatellite instability;
- mismatch repair;
- transforming growth factor-beta receptor type II;
- tissue microarray
Microsatellite instability (MSI) with concomitant mutations in the coding region of transforming growth factor-beta type II receptor (TGFβRII) results in an aberrant growth-regulatory phenotype in colorectal carcinomas. The authors postulated that a similar mechanism occurred during the malignant evolution of small bowel carcinoid tumors.
Mutational analysis of two coding regions in the TGFβRII gene associated with MSI and BAT-26 within intron 5 of the mismatch repair gene, hMSH2, was undertaken in small bowel carcinoids (n = 14), lymph node metasasis (n = 1) and liver metastases (n = 5). Quantitative PCR analysis [TAQMAN, Applied Biosystems, Foster City, CA] was then undertaken to examine gene alterations in mismatch repair genes (hMLH1 and hMSH2) in small bowel carcinoids (n = 7) and matched normal mucosa (n = 5). Staining was then analyzed using quantitative tissue array profiling (AQUA analysis) in a small bowel EC carcinoid tissue microarray (n = 55 tumors) with immunostaining against TGFβRII and MSH2.
Mutational examination of the TFGβRII gene and BAT-26 demonstrated that MSI was not present in any carcinoid material. Q RT-PCR analysis demonstrated statistically significant increased message levels of hMSH2 but not hMLH1 in carcinoid tumors. Quantitative analysis of membrane TGFβRII immunostaining using AQUA demonstrated that TGFβRII expression was down-regulated (P < 0.0002) in thirty-three primary small bowel carcinoids that exhibited lymph node and liver metastases compared to normal mucosa. AQUA analysis of nuclear MSH2 immunostaining demonstrated no differences for MSH2 between normal tissue and carcinoid tumor metastasis. Small bowel carcinoids characterized by variable expression of TGFβRII, did not exhibit MSI and had no differences in MSH2 expression.
The molecular events leading to the formation of carcinoid tumors in the small bowel were different from those resulting in epithelial carcinomas. The usually slow-growing and relatively nonaggressive carcinoid tumors had variable expression of TGFβRII but were associated with the retention of mismatch repair protein function and a microsatellite-stable phenotype. Cancer 2005. © 2004 American Cancer Society.