Epidermal growth factor receptors (hereinafter may be referred to as “EGFRs”) are receptor tyrosine kinases to which ligands such as epidermal growth factors (hereinafter may be referred to as “EGFs”) bind to activate intramembrane kinases to thereby lead to signal transduction. It has been known that although the EGFRs are also present in normal tissues, they are frequently mutated or amplified in cancer tissues to cause oncogenesis.
For example, EGFR genes in genomes are mutated or amplified in about 60% of cancer tissues in patients with glioblastoma, a highly malignant cancer. Moreover, epidermal growth factor receptor mutant vIII (hereinafter may be referred to as “EGFR vIII”) proteins, in which exons 2 to 7 are deleted, are overexpressed in half of the about 60% of cancer tissues. The EGFR vIII proteins are deficient in ligand-binding sites and are constitutively activated without ligands. The EGFR vIII proteins are expressed only in cancer tissues and have been believed to be involved in malignant transformation of cancer.
For example, AG1478, Gefitinib, and Erlotinib, which are EGFR kinase inhibitors, are promising therapeutic drugs for cancers in which mutation or amplification of the EGFRs are involved.
However, they have unsatisfactory anti-cancer effects. Therefore, keen demand has arisen for developing a more effective anti-cancer agent and a screening method for screening such an anti-cancer agent.
Note that, a compound represented by Structural Formula (1) below (hereinafter may be referred to as “Ertredin”) has been reported to inhibit mDia-mediated actin assembly in vitro (see, e.g., NPL 1). However, the compound has not been known to exhibit physiological activities such as kinase inhibiting activities.
