Endocrine Abstracts

Introduction

Somatostatin has antiproliferative, anti-angiogenic and pro-apoptotic actions through 5 G-protein receptors (Sstr). In view of the anti-angiogenic effects of Sstrs their relationship to the distribution of vascular endothelial growth factor (VEGF) was undertaken in non-malignant Reinke's Oedema of the larynx and squamous cell carcinoma of the larynx.

Methods

Six Reinke's oedema (non malignant) and 17 malignant squamous cell carcinoma of the larynx specimens, formalin fixed and paraffin embedded, were immunostained for Sstrs (Sstr1, 2A, 2B, 3, 4 and 5)and VEGF. Heat epitope retrieval and avidin-biotin blocking performed for all sections. 3 detection systems were used. Sstr (1-2 including subtypes 2A &2B) underwent Dako Catalysed Signal Amplification system peroxidase method. VEGF sections underwent Vectastain Universal quick kit method. All staining was visualised with diaminobenzidine. Double labelled immunohistochemistry was carried out with the Dako catalysed system and Sstr (or sst) as discussed above but with Vector NovaRED visualisation, VEGF was then co-immunostained using Vectastain Universal ABC-AP kit and visualised with BCIP/NBT Alkaline Phosphatase.

Results

The number of sections expressing positive Sstr subtype staining in non malignant (n=6) and malignant (n=17) respectively. Sstr1 4/6 and 14/17, sstr2A 1/6 and 4/17, sstr2B 6/6 and 15/17, sstr3 1/6 and 4/17, sstr4 3/6 and 9/6, sstr5 4/6 and 15/17. Also for VEGF staining 6/6 amd 14/17.

Double labelled immunohistochemistry confirmed the co-localisation of Sstr2B and Sstr5 with VEGF, along with co-localisation of somatostatin and VEGF.

Conclusion

All 5 Sstrs and VEGF were expressed in normal and malignant laryngeal tissue. Sstr2B and Sstr5 co-localised with VEGF, and somatostatin and VEGF also co-localised.