Activation and cross-talk between Akt, NF-kappaB, and unfolded protein response signaling in 1-LN prostate cancer cells consequent to ligation of cell surface-associated GRP78.
Binding of activated forms of the proteinase inhibitor alpha2-macroglobulin (alpha2M*) to cell surface-associated GRP78 on 1-LN human prostate cancer cells causes their proliferation. We have now examined the interplay between Akt activation, regulation of apoptosis, the unfolded protein response, and activation of NF-kappaB in alpha2M*-induced proliferation of 1-LN cells. Exposure of cells to alpha2M* (50 pM) induced phosphatidylinositol 3-kinase-dependent activation of Akt by phosphorylation at Thr-308 and Ser-473 with a concomitant 60-80% increase in Akt-associated kinase activity. ERK1/2 and p38 MAPK were also activated, but there was only a marginal effect on JNK activation. Treatment of 1-LN cells with alpha2M* down-regulated apoptosis and promoted NF-kappaB activation as shown by increases of Bcl-2, p-Bad(Ser-136), p-FOXO1(Ser-253), p-GSK3beta(Ser-9), XIAP, NF-kappaB, cyclin D1, GADD45beta, p-ASK1(Ser-83), and TRAF2 in a time of incubation-dependent manner. alpha2M* treatment of 1-LN cells, however, showed no increase in the activation of caspase -3, -9, or -12. Under these conditions, we observed increased unfolded protein response signaling as evidenced by elevated levels of GRP78, IRE1alpha, XBP-1, ATF4, ATF6, p-PERK, p-eIF2alpha, and GADD34 and reduced levels of GADD153. Silencing of GRP78 gene expression by RNAi suppressed activation of Akt(Thr-308), Akt(Ser-473), and IkappaB kinase alpha kinase. The effects of alpha2M* on the NF-kappaB activation, antiapoptotic signaling, unfolded protein response signaling, and proapoptotic signaling were also reversed by this treatment. In conclusion, alpha2M* promotes cellular proliferation of 1-LN prostate cancer cells by activating MAPK and Akt-dependent signaling, down-regulating apoptotic signaling, and activating unfolded protein response signaling.
Department of Pathology, Duke University, Medical Center, Durham, North Carolina 27710.
Uma Kant
UK
Misra
Department of Pathology, Duke University, Medical Center, Durham, North Carolina 27710.
Rohit
R
Deedwania
Department of Pathology, Duke University, Medical Center, Durham, North Carolina 27710. Electronic address: Pizzo001@mc.duke.edu.
Salvatore Vincent
SV
Pizzo
D017209:Apoptosis / Q000502:physiology; D045744:Cell Line, Tumor; D000091342:Endoplasmic Reticulum Chaperone BiP; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000378:metabolism*; D011489:Protein Denaturation; D017510:Protein Folding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D015398:Signal Transduction; D015854:Up-Regulation; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000378:metabolism
D000091342:Endoplasmic Reticulum Chaperone BiP; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D006360:Heat-Shock Proteins; D020928:Mitogen-Activated Protein Kinases; D018832:Molecular Chaperones; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D051636:X-Linked Inhibitor of Apoptosis Protein; D000511:alpha-Macroglobulins; C085126:FOXO1 protein, human; C000717247:HSPA5 protein, human; C496866:XIAP protein, human; C000605506:GSK3B protein, human