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Toward a PKB inhibitor: modification of a selective PKA inhibitor by rational design
Hadas Reuveni1, Nurit Livnah, Tamar Geiger
1Department of Biological Chemistry, The Silverman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel, and Peptor Ltd., Rehovot, Israel.
Abstract:
Protein kinase B/Akt (PKB) is an anti-apoptotic protein kinase that has strongly elevated activity in human malignancies. We therefore initiated a program to develop PKB inhibitors, "Aktstatins". We screened about 500 compounds for PKB inhibitors, using a radioactive assay and an ELISA assay that we established for this purpose. These compounds were produced as combinatorial libraries, designed using the structure of the selective PKA inhibitor H-89 as a starting point. We have identified a successful lead compound, which inhibits PKB activity in vitro and in cells overexpressing active PKB. The new compound shows reversed selectivity to H-89: In contrast to H-89, which inhibits PKA 70 times better than PKB, the new compound, NL-71-101, inhibits PKB 2.4-fold better than PKA. The new compound, but not H-89, induces apoptosis in tumor cells in which PKB is amplified. We have identified structural features in NL-71-101 that are significant for the specificity and that can be used for future development and optimization of PKB inhibitors.
Insights
Researchers developed novel "Aktstatins" to inhibit elevated Protein Kinase B/Akt (PKB) activity in cancer. A lead compound, NL-71-101, selectively inhibits PKB over PKA and induces apoptosis in tumor cells.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Protein Kinase B/Akt (PKB) is a key anti-apoptotic protein with elevated activity in human malignancies.
- Targeting PKB is a promising strategy for cancer therapy.
Purpose of the Study:
- To develop novel inhibitors of PKB, termed "Aktstatins".
- To identify a lead compound with selective PKB inhibitory activity.
Main Methods:
- Screening of approximately 500 compounds using radioactive and ELISA assays.
- Design of combinatorial libraries based on the PKA inhibitor H-89 structure.
- In vitro and cellular assays to evaluate PKB inhibition and selectivity.
Main Results:
- Identification of a lead compound, NL-71-101, that inhibits PKB in vitro and in cells overexpressing active PKB.
- NL-71-101 exhibits reversed selectivity compared to H-89, inhibiting PKB 2.4-fold better than PKA.
- NL-71-101, unlike H-89, induces apoptosis in tumor cells with amplified PKB.
Conclusions:
- NL-71-101 is a promising lead compound for developing novel PKB inhibitors.
- Structural features of NL-71-101 are identified for optimization of PKB inhibitors.
- Targeting PKB with selective inhibitors like NL-71-101 holds therapeutic potential for cancers with elevated PKB activity.