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.
Misra
Uma Kant
UK
Department of Pathology, Duke University, Medical Center, Durham, North Carolina 27710.
Deedwania
Rohit
R
Department of Pathology, Duke University, Medical Center, Durham, North Carolina 27710.
Pizzo
Salvatore Vincent
SV
Department of Pathology, Duke University, Medical Center, Durham, North Carolina 27710. Electronic address: Pizzo001@mc.duke.edu.
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