Increased expression of apoptotic markers in melanoma

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Abstract
Extensive labelling for the apoptotic markers calcium channel receptor P2X7 and caspase-3 and telomerase activity was co-localized at a similar intensity in areas affected by superficial spreading melanoma obtained from 80 patients. Labelling for each of these markers also extended 2μm from the melanoma into the keratinocyte layer of the adjacent normal epidermis. Conversely, the calcium-regulating receptors P2X1–3 and P2Y2 (found in normal but not neoplastic skin) were fully de-expressed within 2μm of the melanoma but fully expressed beyond that distance. The cell adhesion protein E-cadherin (also only present in normal skin) was progressively de-expressed from a point 2μm from the melanoma until full de-expression within the lesion. These results show that telomerase-induced proliferation and defensive apoptosis are co-localized and simultaneous processes in melanoma tissue. Melanoma cell proliferation appears to overwhelm the apoptotic defence, perhaps due to the anti-apoptotic effects of telomerase. In addition, keratinocyte regulation of the epidermis and dermis is severely compromised by the loss of E-cadherin and P2X1–3 and P2Y2 receptors, resulting in a lesion that is aggressive and malignant.