PMID- 18562482 OWN - NLM STAT- MEDLINE DCOM- 20081113 LR - 20211020 IS - 0363-6143 (Print) IS - 1522-1563 (Electronic) IS - 0363-6143 (Linking) VI - 295 IP - 2 DP - 2008 Aug TI - Pregnancy-upregulated nonubiquitous calmodulin kinase induces ligand-independent EGFR degradation. PG - C365-77 LID - 10.1152/ajpcell.00449.2007 [doi] AB - We describe here an important function of the novel calmodulin kinase I isoform, pregnancy-upregulated nonubiquitous calmodulin kinase (Pnck). Pnck (also known as CaM kinase Ibeta(2)) was previously shown to be differentially overexpressed in a subset of human primary breast cancers, compared with benign mammary epithelial tissue. In addition, during late pregnancy, Pnck mRNA was shown to be strongly upregulated in epithelial cells of the mouse mammary gland exhibiting decreased proliferation and terminal differentiation. Pnck mRNA is also significantly upregulated in confluent and serum-starved cells, compared with actively growing proliferating cells (Gardner HP, Seung HI, Reynolds C, Chodosh LA. Cancer Res 60: 5571-5577, 2000). Despite these suggestive data, the true physiological role(s) of, or the signaling mechanism(s) regulated by Pnck, remain unknown. We now report that epidermal growth factor receptor (EGFR) levels are significantly downregulated in a ligand-independent manner in human embryonic kidney-293 (HEK-293) cells overexpressing Pnck. MAP kinase activation was strongly inhibited by EGFR downregulation in the Pnck-overexpressing cells. The EGFR downregulation was not the result of reduced transcription of the EGFR gene but from protea-lysosomal degradation of EGFR protein. Knockdown of endogenous Pnck mRNA levels by small interfering RNA transfection in human breast cancer cells resulted in upregulation of unliganded EGFR, consistent with the effects observed in the overexpression model of Pnck-mediated ligand-independent EGFR downregulation. Pnck thus emerges as a new component of the poorly understood mechanism of ligand-independent EGFR degradation, and it may represent an attractive therapeutic target in EGFR-regulated oncogenesis. FAU - Deb, Tushar B AU - Deb TB AD - Dept. of Oncology, Lombardi Comprehensive Cancer Center, Georgetown Univ. Medical Center, New Research Bldg., W412, 3970 Reservoir Rd., NW, Washington, DC 20057, USA. tbd@georgetown.edu FAU - Coticchia, Christine M AU - Coticchia CM FAU - Barndt, Robert AU - Barndt R FAU - Zuo, Hong AU - Zuo H FAU - Dickson, Robert B AU - Dickson RB FAU - Johnson, Michael D AU - Johnson MD LA - eng GR - 2P50CA58185/CA/NCI NIH HHS/United States GR - 2R01-AG-014963/AG/NIA NIH HHS/United States GR - NIH 4P30CA51008/CA/NCI NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural PT - Research Support, Non-U.S. Gov't PT - Research Support, U.S. Gov't, Non-P.H.S. DEP - 20080618 PL - United States TA - Am J Physiol Cell Physiol JT - American journal of physiology. Cell physiology JID - 100901225 RN - 0 (Adaptor Proteins, Signal Transducing) RN - 0 (Intracellular Signaling Peptides and Proteins) RN - 0 (Leupeptins) RN - 0 (Ligands) RN - 0 (Macrolides) RN - 0 (Phosphoproteins) RN - 0 (Protease Inhibitors) RN - 0 (Proteasome Inhibitors) RN - 0 (Protein Kinase Inhibitors) RN - 0 (Quinazolines) RN - 0 (RNA, Small Interfering) RN - 0 (Recombinant Fusion Proteins) RN - 0 (SHC1 protein, human) RN - 0 (Shc Signaling Adaptor Proteins) RN - 0 (Shc1 protein, mouse) RN - 0 (Src Homology 2 Domain-Containing, Transforming Protein 1) RN - 0 (Tyrphostins) RN - 170449-18-0 (RTKI cpd) RN - 62229-50-9 (Epidermal Growth Factor) RN - 88899-55-2 (bafilomycin A1) RN - EC 2.7.10.1 (ErbB Receptors) RN - EC 2.7.11.17 (Calcium-Calmodulin-Dependent Protein Kinase Type 1) RN - EC 2.7.11.17 (PNCK protein, human) RN - EC 2.7.11.24 (Extracellular Signal-Regulated MAP Kinases) RN - EC 3.4.25.1 (Proteasome Endopeptidase Complex) RN - RF1P63GW3K (benzyloxycarbonylleucyl-leucyl-leucine aldehyde) SB - IM MH - Adaptor Proteins, Signal Transducing/metabolism MH - Calcium-Calmodulin-Dependent Protein Kinase Type 1/genetics/*metabolism MH - Cell Line MH - Down-Regulation MH - Epidermal Growth Factor/pharmacology MH - Epithelial Cells/drug effects/metabolism MH - ErbB Receptors/*metabolism MH - Extracellular Signal-Regulated MAP Kinases/metabolism MH - Gene Expression/drug effects MH - Humans MH - Intracellular Signaling Peptides and Proteins/metabolism MH - Leupeptins/pharmacology MH - Ligands MH - Lysosomes/metabolism MH - Macrolides/pharmacology MH - Phosphoproteins/metabolism MH - Phosphorylation/drug effects MH - Protease Inhibitors/pharmacology MH - Proteasome Endopeptidase Complex/metabolism MH - Proteasome Inhibitors MH - Protein Kinase Inhibitors/pharmacology MH - Quinazolines MH - RNA, Small Interfering/genetics MH - Recombinant Fusion Proteins/genetics/metabolism MH - Shc Signaling Adaptor Proteins MH - Src Homology 2 Domain-Containing, Transforming Protein 1 MH - Transfection MH - Tyrphostins/pharmacology PMC - PMC2518423 EDAT- 2008/06/20 09:00 MHDA- 2008/11/14 09:00 PMCR- 2009/08/01 CRDT- 2008/06/20 09:00 PHST- 2008/06/20 09:00 [pubmed] PHST- 2008/11/14 09:00 [medline] PHST- 2008/06/20 09:00 [entrez] PHST- 2009/08/01 00:00 [pmc-release] AID - 00449.2007 [pii] AID - C-00449-2007 [pii] AID - 10.1152/ajpcell.00449.2007 [doi] PST - ppublish SO - Am J Physiol Cell Physiol. 2008 Aug;295(2):C365-77. doi: 10.1152/ajpcell.00449.2007. Epub 2008 Jun 18.