In vivo evaluation of type 2 transglutaminase contribution to the metastasis formation in melanoma

One of the most relevant problems in tumour treatment resides on the ability of the tumour to form metastasis and disseminate among the organism. The formation of metastases is a complex process, which requires the action of various effectors, not yet completely identified. The analysis of various types of tumours revealed a complex picture about the relationship between type 2 transglutaminase (TG2) expression and outcome and/or metastatic potential of the tumour itself. In some tumours, the transition to a highly invasive state is paralleled by an up-regulation of TG2 expression and/or activity while in some other a down-regulation has been reported. In addition, host tissues seem to react to tumour invasion by up-regulating TG2 expression. In order to analyse whether TG2 might be involved in the metastatic process in melanoma, we studied the metastases formation and development by means of the B16-F10 murine melanoma cell line and with TG2^-/- mice as experimental model. Our results indicate that TG2 absence in the host is a favouring condition for the formation and development of the metastasis, while the presence of TG2 in the tumour's cell might be requested for the development of the metastasis.