Sensitivity of UCN-01 lies in the balance of CDK 2 kinase and p21
Abe, S.; Kubota, T.; Otani, Y.; Furukawa, T.; Watanabe, M.; Kumai, K.; Kitajima, M.
Gan to Kagaku Ryoho. Cancer and ChemoTherapy 27(8): 1260-1266
2000
ISSN/ISBN: 0385-0684 PMID: 10945025 Document Number: 512893
Five human cancer cell lines (MKN 45, HT-29, WiDr, PAN-3-JCK, and CRL 1420) were used to evaluate the antitumor spectrum of UCN-01, which suppressed the growth of these digestive cancer cell lines. A human pancreatic cancer xenograft (CRL 1420) and breast cancer xenograft (MX-1) were used to determine their sensitivity to UCN-01, in nude mice. UCN-01 significantly suppressed the tumor growth of CRL 1420 at a dose of 10 mg/kg in a schedule of (qd x 5) x 2, but was ineffective for MX-1. While p21 protein expression was induced by UCN-01 in both CRL 1420 and MX-1, an accumulation of dephosphorylated ppRb was observed only in CRL 1420, resulting in G1 block as detected by flow cytometric analysis. The CDK 2 activity of MX-1 was almost 6 times higher than that of CRL 1420, which might account for the resistance of MX-1 to UCN-01 in spite of the induction of p21 in this strain. We conclude that the determinant of sensitivity to UCN-01 lies in the balance of CDK 2 kinase activity and p21 protein induction.