Uma nova abordagem de cancro baseada na teoria das células estaminais

Abstract

Stem cells are being intensively studied because, in addition to therapeutic weapons, they can also be targets in treatment strategies of many diseases, namely in cancer, where they have an important etiologic role. Classical regulatory pathways of stem cells are deregulated in several tumours, strengthening the role of these cells in the carcinogenesis process. The mammary gland is a good model for studying carcinogenesis because of its unique anatomic, functional and pathologic characteristics. There are several exceptional experimental models used in etiologic, pathophysiologic, diagnostic and therapeutic research in cancer using this complex organ. After isolation of tumoural stem cells in the haematopoietic system, the breast and brain were the organs whose solid tumours were studied in order to isolate stem cells. In this article, a monoclonal theory of cancer is presented, supported by the stem cell theory and by extensive experimental work. Stem cells mutations would be in the origin of the most aggressive and undifferentiated tumors, whereas tumours with better prognosis would be originated in more differentiated progenitor cells. The higher aggressiveness of the former could be explained by expression of MDR proteins in stem cells. The protective role of pregnancy in breast cancer, would in the light of the exposed theory, be explained by the inhibitory influences of differentiated tissue. The isolation of tumour stem cells, combined with profound knowledge of cancer regulatory pathways, may lead us to develop, in the short future, specific therapeutic strategies that could transform cancer into a treatable or chronic disease.