Effects of polyamine imbalance on the induction of stress genes in hepatocarcinoma cells exposed to heat shock.
The expression of hsp70-the inducible member of the corresponding heat shock gene family-of the oxidative stress marker gene heme oxygenase (HOx), and of the immediate early response genes c-fos and c-jun has been studied in FAO hepatocarcinoma cells depleted of polyamines and exposed to heat shock. Depletion of polyamines was obtained in short-term experiments (24-48 hours) by the use of alpha difluoromethylornithine (DFMO), a classical inhibitor of ornithine decarboxylase (ODC), or of the combination of the newly available inhibitors of ODC and S-adenosylmethionine decarboxylase, i.e., (2R,5R)-hept-6-yne-2,5-diamine (MAP) and 5'{[(Z)-4-aminobut-2-enyl]methylanino}-5-deoxyadeno-si ne (AbeAdo). Under our experimental conditions polyamine imbalance was realized without appreciable growth-related genes. Decreases of putrescine and spermidine 48 hours after DFMO prevented the induction of hsp70 messenger RNA (mRNA), whereas depletion spermidine and spermine obtained with MAP/AbeAdo decreased intensity and duration of post-heat shock accumulation of hsp70 mRNA. Inductions of HOx, c-jun and c-fos were also inhibited. Because MAP/AbeAdo caused also an intracelluar accumulation of putrescine, we tested the effect of exogenous putrescine, which was found to stabilize the mRNAs for hsp70 and c-jun. Hsp70 and HOx are thought to play a protective role, and the proteins of c-jun and c-fos constitute the transcription factor activator protein-1, which is involved in the transcription of many defensive products. Therefore, the integrity of polyamine pool seems to be a necessary permissive condition for an effective response of the cells to adverse environmental changes.
Desiderio
M A
MA
Istituto di Patologia Generale dell'Università degli Studi di Milano and Centro di Studio sulla Patologia Cellulare del CNR, Milano, Italy.
Tacchini
L
L
Anzon
E
E
Pogliaghi
G
G
Radice
L
L
Bernelli-Zazzera
A
A
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D000518:Eflornithine / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D017781:Genes, Immediate-Early / Q000187:drug effects*; D016762:Genes, fos; D016758:Genes, jun; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis; D006657:Histones / Q000096:biosynthesis; D006801:Humans; D007700:Kinetics; D008114:Liver Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism*; D009955:Ornithine Decarboxylase / Q000378:metabolism; D011073:Polyamines / Q000302:isolation & purification / Q000378:metabolism*; D011700:Putrescine / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D013095:Spermidine / Q000494:pharmacology; D013096:Spermine / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D018840:HSP70 Heat-Shock Proteins; D006657:Histones; D011073:Polyamines; D012333:RNA, Messenger; D013096:Spermine; D006419:Heme Oxygenase (Decyclizing); D009955:Ornithine Decarboxylase; D013095:Spermidine; D011700:Putrescine; D000518:Eflornithine