title: Comparison of transcriptional response to phorbol ester, bryostatin 1, and bryostatin analogs in LNCaP and U937 cancer cell lines provides insight into their differential mechanism of action.
abstract: Bryostatin 1, like the phorbol esters, binds to and activates protein kinase C (PKC) but paradoxically antagonizes many but not all phorbol ester responses. Previously, we have compared patterns of biological response to bryostatin 1, phorbol ester, and the bryostatin 1 derivative Merle 23 in two human cancer cell lines, LNCaP and U937. Bryostatin 1 fails to induce a typical phorbol ester biological response in either cell line, whereas Merle 23 resembles phorbol ester in the U937 cells and bryostatin 1 in the LNCaP cells. Here, we have compared the pattern of their transcriptional response in both cell lines. We examined by qPCR the transcriptional response as a function of dose and time for a series of genes regulated by PKCs. In both cell lines bryostatin 1 differed primarily from phorbol ester in having a shorter duration of transcriptional modulation. This was not due to bryostatin 1 instability, since bryostatin 1 suppressed the phorbol ester response. In both cell lines Merle 23 induced a pattern of transcription largely like that of phorbol ester although with a modest reduction at later times in the LNCaP cells, suggesting that the difference in biological response of the two cell lines to Merle 23 lies downstream of this transcriptional regulation. For a series of bryostatins and analogs which ranged from bryostatin 1-like to phorbol ester-like in activity on the U937 cells, the duration of transcriptional response correlated with the pattern of biological activity, suggesting that this may provide a robust platform for structure activity analysis.
authors.affiliation: Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA. kedein@mail.nih.gov
authors.forename: N
authors.initials: N
authors.lastname: Kedei
authors.forename: A
authors.initials: A
authors.lastname: Telek
authors.forename: A M
authors.initials: AM
authors.lastname: Michalowski
authors.forename: M B
authors.initials: MB
authors.lastname: Kraft
authors.forename: W
authors.initials: W
authors.lastname: Li
authors.forename: Y B
authors.initials: YB
authors.lastname: Poudel
authors.forename: A
authors.initials: A
authors.lastname: Rudra
authors.forename: M E
authors.initials: ME
authors.lastname: Petersen
authors.forename: G E
authors.initials: GE
authors.lastname: Keck
authors.forename: P M
authors.initials: PM
authors.lastname: Blumberg
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D054713:Bryostatins / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D015394:Molecular Structure; D010703:Phorbol Esters / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors
chemical_list: D000970:Antineoplastic Agents; D054713:Bryostatins; D010703:Phorbol Esters; C046785:bryostatin 1; D011493:Protein Kinase C