title: Downregulation of Hsp70 inhibits apoptosis induced by sialic acid-binding lectin (leczyme).
abstract: Heat shock proteins (Hsps) are molecular chaperones that maintain homeostasis of organisms. In regards to the Hsps, many studies have investigated the structure, expression, localization and functions of Hsp70 and Hsc70 including expression in the glycosphingolipid-enriched microdomain (GEM) on the cell surface and involvement in cell death. Sialic acid-binding lectin (SBL) isolated from oocytes of Rana catesbeiana is a multifunctional protein which has lectin activity, ribonuclease activity and antitumor activity. SBL has potential as a new type of anticancer drug, since it causes cancer-selective induction of apoptosis by multiple signaling pathways in which RNA is its target; and the participation of the mitochondrial pathway and the endoplasmic reticulum (ER) stress-mediated pathway has been suggested. It has also been suggested that receptor(s) for SBL (SBLR) may exist in the GEM on the cell surface. In the present study, we studied the possible involvement of Hsp70 and Hsc70 in SBL-induced apoptosis. We showed that Hsp70 and Hsc70 were expressed on the P388 cell surface similar to SBLR, and their distribution in cells dramatically changed immediately prior to the execution of apoptosis following stimulation of SBL. Functional study of Hsp70 revealed that decreased expression of Hsp70 diminished the apoptosis induced by SBL. It is suggested that Hsp70 participates in the antitumor effect of SBL.
authors.affiliation: Division of Cell Recognition Study, Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, Sendai 981-8558, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Tatsuta
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hosono
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Ogawa
authors.forename: Kyoko
authors.initials: K
authors.lastname: Inage
authors.forename: Shigeki
authors.initials: S
authors.lastname: Sugawara
authors.forename: Kazuo
authors.initials: K
authors.lastname: Nitta
mesh_terms: D029845:Amphibian Proteins / Q000494:pharmacology*; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D045744:Cell Line, Tumor; D004721:Endoplasmic Reticulum / Q000378:metabolism; D059865:Endoplasmic Reticulum Stress; D050883:HSC70 Heat-Shock Proteins / Q000096:biosynthesis*; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D037102:Lectins / Q000494:pharmacology*; D008565:Membrane Proteins / Q000096:biosynthesis; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011794:Quercetin / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011892:Rana catesbeiana; D012260:Ribonucleases / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D029845:Amphibian Proteins; D000970:Antineoplastic Agents; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D037102:Lectins; D008565:Membrane Proteins; D012333:RNA, Messenger; D011794:Quercetin; D012260:Ribonucleases; C448662:leczyme protein, Rana