Hashimoto S, Xu Y, Masuda Y, Aiuchi T, Nakajo S, Uehara Y, Shibuya M, Yamori T, Nakaya K. Beta-hydroxyisovalerylshikonin is a novel and potent inhibitor of protein tyrosine kinases.
Jpn J Cancer Res 2002;
93:944-51. [PMID:
12716473 PMCID:
PMC5927115 DOI:
10.1111/j.1349-7006.2002.tb01341.x]
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Abstract
Beta-hydroxyisovalerylshikonin (beta-HIVS), a compound isolated from Lithospermium radix, most efficiently induced cell-death in two lines of lung cancer cells, namely, NCI-H522 and DMS114, whereas shikonin was effective against a wide variety of tumor cell lines. During our studies of the mechanism of action of beta-HIVS on tumor cells, we found that this compound inhibited protein tyrosine kinase (PTK) activity. The tyrosine kinase activities of a receptor for EGF (EGFR) and v-Src were strongly inhibited and that of KDR/Flk-1 was weakly inhibited by beta-HIVS. The inhibition by beta-HIVS of the activities of EGFR and v-Src was much stronger than that by shikonin. The IC50 values of beta-HIVS for EGFR and v-Src were approximately 0.7 microM and 1 microM, respectively. Moreover, the inhibition of v-Src by beta-HIVS was non-competitive with respect to ATP. These results strongly suggest that the action of beta-HIVS, as well as that of shikonin, involves the inhibition of PTK, and they also suggest the possibility of producing a novel group of PTK inhibitors based on shikonin as the parent compound.
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