Rapamycin suppresses the expansion and differentiation of porcine neonatal pancreas cell clusters.
BACKGROUND
The role of rapamycin in pancreas stem cells remains to be clearly elucidated. Herein, we evaluated the effects of rapamycin on porcine neonatal pancreas cell clusters (NPCCs), which primarily comprised pancreatic precursors, and attempted to find an intracellular mechanism about the harmful effects of rapamycin.


METHODS
Porcine NPCCs were treated with rapamycin in a monolayer, and the apoptosis and proliferation were determined via caspase-3 assay and H-thymidine uptake analysis. The expression of transcription factors was assessed via reverse-transcriptase polymerase chain reaction and Western blotting. For the in vivo study, the porcine NPCCs were transplanted into the kidney subcapsules of normal nude mice and treated with rapamycin.


RESULTS
Rapamycin treatment significantly reduced the number of β cells, glucose-stimulated insulin secretion, and the insulin contents in the monolayer-cultured porcine NPCCs. Furthermore, rapamycin treatment increased the apoptosis and inhibited the proliferation of β cells in the culture dishes. The expressions of the insulin, pancreatic and duodenal homeobox-1, and NeuroD/Beta2 genes were down-regulated via rapamycin treatment. The expression of insulin-like growth factor-II was significantly down-regulated, but the expression of Foxo1 was simultaneously inversely increased, and the translocation of Foxo1 from the cytoplasm to the nucleus was induced by rapamycin treatment. Moreover, rapamycin treatment induced a marked reduction in the relative volume and absolute mass of β cells in the porcine NPCCs grafts at 8 weeks after transplantation in the normal nude mice.


CONCLUSIONS
Here, we demonstrate that rapamycin treatment suppresses the expansion and differentiation of porcine NPCCs, and the alteration of Foxo1 and insulin-like growth factor-II gene expression might be the crucial factors.
Sun
Cheng-Lin
CL
Department of Endocrinology and Metabolism, The Catholic University of Korea, Seoul, Korea.
Ham
Dong-Sik
DS
Park
Heon-Seok
HS
Kim
Ji-Won
JW
Cho
Jae-Hyoung
JH
Song
Ki-Ho
KH
Son
Ho-Young
HY
Yoon
Kun-Ho
KH
D000818:Animals; D000831:Animals, Newborn; D053148:Caspase 3 / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D017931:DNA Primers; D004261:DNA Replication / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D007328:Insulin / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010179:Pancreas / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D010180:Pancreatectomy; D016133:Polymerase Chain Reaction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D013552:Swine
D017931:DNA Primers; D007328:Insulin; D053148:Caspase 3; D020123:Sirolimus