Characterization of Chemopreventive and Chemotherapeutical Activities and Compound(s) from an Amazonian Plant

摘要

Worldwide, cancer accounts for more than 6 million deaths annually (1). According to estimates from the American Cancer Society' (2), approximately 1.2 million new cancer cases were to be diagnosed in 1998 in the United States, including 178,700 diagnoses of breast cancer in women. Polypeptide growth factors play important roles in both normal and pathological development of the breast. Such growth factors promote cell proliferation, motility and invasiveness of epithelial cells in vifro, properties that are required for tumor invasiveness and metastasis. Recent experimental evidence suggests that estrogens stimulate breast proliferation in hormone-dependent cells by upregulation of an autocrine stimulatory loop involving epidermal growth factor receptor related tyrosine kinases (erbB-2) (3,4). The erbB-2 oncogene product has been shown to be expressed in approximately 25-30% of breast cancer patients, and has been correlated with poor prognosis and unfavorable survival rate (5,6). Frequently, patients whose tumors express erbB-2 receptors do not respond well to conventional therapies, emphasizing the need for more aggressive therapies. Although the exact role of erbB-2 in tumor development has yet to be elucidated, tyrosine kinase-mediated signal transduction appears to play an important role in breast cancer progression and metastasis.