Background: Muscarinic acetylcholine receptors (mR) are involved in the regulation of cancer cell motility and cancer progression. mR have been shown in melanoma cell lines and cryostat sections of melanomas. To substantiate the experimental data, here the correlation of mR-expression with invasive growth was studied on the cellular level by comparison with HMB-45 immunoreactivity.
Methods: mR were detected by a M3 subtype-specific polyclonal antibody in normal skin, benign compound nevi, primary melanomas [nodular type, nodular malignant melanoma (NMM)] and metastases, and were compared with HMB-45 staining in parallel paraffin sections.
Results: The general staining pattern of anti-M3 and HMB-45 was similar with accentuation of zones with infiltrative growth. On the cellular level, only a subpopulation of the HMB-45 positive melanoma cells expressed mR. Immunoreactivity was encountered in 3 of 15 nevi, in 9 of 14 NMM and in 10 of 14 melanoma metastases. Polymorphonuclear granulocytes also exhibited strong reactivity for anti-M3.
Conclusion: mR-expression is associated with invasive migration of melanomas.