Related Experiment Video
Updated: Jul 29, 2026
Endobronchial Ultrasound-guided Intratumoral Injection of Cisplatin for the Treatment of Isolated Mediastinal Recurrence of Lung Cancer
Published on: February 12, 2017
RB status as a determinant of response to UCN-01 in non-small cell lung carcinoma
P C Mack1, D R Gandara, C Bowen
1Cancer and Molecular Research Laboratory, Department of Internal Medicine, University of California, Davis, Sacramento 95817, USA.
Abstract:
7-Hydroxystaurosporine (UCN-01), a protein kinase inhibitor in clinical development, demonstrates potent antineoplastic activity. To determine whether specific genetic abnormalities would modulate the response to UCN-01, a model of human non-small cell lung carcinoma (NSCLC) cell lines with differential abnormalities of p16CDKN2, RB, and p53 was used for these studies. Cell growth was measured by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay, and cell cycling was studied using flow cytometric analysis of DNA content. Changes in protein levels and phosphorylation were assessed by Western blotting. In cell lines expressing wild-type RB (A549 and Calul), UCN-01 treatment resulted in dose-dependent growth inhibition, arrest of cells in G1, and a reduction of cells in S phase. p16CDKN2-null cells showed similar growth inhibition to normal fetal lung fibroblasts. UCN-01-induced growth arrest was accompanied by induction of p21CDKN1 and a shift of Rb to the hypophosphorylated state in both p53 wild-type and mutant cell lines. In contrast, UCN-01 treatment of the RB-null cell line H596 resulted in less growth inhibition. To test the role of RB in response to UCN-01, effects of treatment were examined in two human isogenic models of RB expression: the bladder cancer cell line 5637 (RB-null) and the prostate cancer cell line DU-145 (RB-mutant). In the Rb-expressing 5637 subline (RB5), UCN-01 treatment resulted in Rb hypophosphorylation and an accumulation in G1 in contrast to the parent line. Similarly, the wild-type Rb-expressing DU-145 sublines (DU1.1 and B5) showed increased G1 arrest compared with the parent cells. We conclude that UCN-01-induced G1 arrest can occur in cells null for p53 and p16CDKN2, and that RB status influences the ability of UCN-01 to induce a G1 arrest. These data suggest that the molecular profile of cell cycle regulating genes in individual tumors may predict responsiveness and provide insight into optimal therapeutic application of this new antineoplastic agent.
Insights
7-Hydroxystaurosporine (UCN-01) effectively inhibits cancer cell growth by arresting cells in the G1 phase. Its efficacy is influenced by the Retinoblastoma (RB) protein status, suggesting RB
Area of Science:
- Molecular Oncology
- Cell Cycle Regulation
- Cancer Therapeutics
Background:
- 7-Hydroxystaurosporine (UCN-01) is a potent protein kinase inhibitor with demonstrated antineoplastic activity.
- Understanding the genetic factors influencing UCN-01 response is crucial for optimizing its therapeutic application.
Purpose of the Study:
- To investigate how genetic abnormalities in p16CDKN2, RB, and p53 modulate the response to UCN-01 in non-small cell lung carcinoma (NSCLC) cells.
- To elucidate the role of Retinoblastoma (RB) protein status in UCN-01-induced cell cycle arrest.
Main Methods:
- Utilized a panel of human NSCLC cell lines with differential genetic abnormalities.
- Assessed cell growth using the MTT assay.
- Analyzed cell cycle progression via flow cytometry and protein level/phosphorylation changes using Western blotting.
Main Results:
- UCN-01 induced dose-dependent G1 arrest and reduced S-phase fraction in cell lines with wild-type RB.
- RB-null cells exhibited less growth inhibition compared to RB-expressing counterparts.
- UCN-01 treatment led to p21CDKN1 induction and RB hypophosphorylation, irrespective of p53 status.
Conclusions:
- UCN-01-induced G1 arrest is achievable in cells lacking p53 and p16CDKN2.
- RB status significantly influences the efficacy of UCN-01 in inducing G1 arrest.
- Tumor molecular profiling of cell cycle regulators may predict UCN-01 responsiveness.
