Endocrine Abstracts (2004) 7 P111

Expression of SSTR subtypes (1-5) in normal and malignant colonic tissue

BW Ogunkolade1, PD Kelly1, PD Fairclough2, S Khalaf1, SA Bustin3 & PJ Jenkins1


1Department of Endocrine oncology, St. Bartholomew's and The London, Queen Mary's School of Medicine and Dentistry, London, UK; 2Department of Gastroenterology, St. Bartholomew's and The London, Queen Mary's School of Medicine and Dentistry, London, UK; 3Depts of Academic Surgery, St. Bartholomew's and The London, Queen Mary's School of Medicine and Dentistry, London, UK.


Background

In addition to inhibiting pituitary GH secretion, somatostatin (SS) and its analogues have been shown to exert anti-proliferative effects on a variety of different cell types. The presence of receptors for SS have been demonstrated in a number of tissues but quantification of mRNA expression of the 5 subtypes of SSTR in the colon is unknown.

Methods

Total RNA was extracted from 9 paired samples of adjacent normal (AN) and malignant (T) colon obtained at surgery, from 9 biopsies of normal colon (NN) obtained at colonoscopy from patients without colonic pathology, and from HT29 cells, a human colorectal cancer cell line. Informed consent was obtained from all patients. mRNA levels for SS and SSTR subtypes 1-5 were quantified using real-time RT-PCR (Taqman) and expressed as copy number/ ug total RNA.

Results

SS was expressed by all NN patients (median copy no 4.20E+06) but in only 6/9 AN (1.40E+05, p=<0.05) and only 3/9 T patients (2.00E+00, p<0.05).

All patients expressed SSTR-1 - median of 9.69E+07 (NN), 3.69E+07 (AN), 2.11E+07 (T) respectively. There was no difference in the universal expression level of SSTR-3 and SSTR-5 between NN, AN and T samples but SSTR-2 and SSTR-4 mRNA levels were higher in NN (5.90E+07 and 4.22E+07 respectively) than AN (4.91E+07 and 1.83E+07 respectively) and significantly higher than T (1.76E+07 and 8.65E+06 respectively p<0.05).

Conclusions

The increased expression of SS in normal colon suggests a local role for this peptide in tissue homeostasis. The universal expression of all the SSTR subtypes in colon cancer offers potential chemotherapeutic benefit with broad-acting SS analogues such as SOM 230.

Article tools

My recent searches

No recent searches.