Apoptosis of pregnancy-dependent mammary tumor and transplantable pregnancy-dependent mammary tumor in mice.
Pregnancy-dependent mammary tumors (PDMT) of GR/A mice and transplantable PDMT (TPDMT-4 line) in DDD mice, are exceptionally stable in hormone dependence, continue to grow until parturition and regress soon after delivery. In order to study the regression mechanism of PDMT and TPDMT-4, morphological and biochemical changes were examined in the tumors removed on day 18 (TPDMT-4) or day 20 (PDMT) of pregnancy, and on the expected parturient and the following postpartum days. DNA fragmentation occurred from day 18 (TPDMT-4) or day 20 (PDMT) of pregnancy to the day after parturition. Apoptotic cells were demonstrated by an in situ 3'-end labeling method, and the plateau of the number of apoptotic cells was observed on the parturient day in PDMT and on the day after parturition in TPDMT-4. Reverse transcriptase polymerase chain reaction showed that expression of Fas was slightly increased but that of bcl-2 was decreased during the process of involution of TPDMT-4 and PDMT. These results suggest that both an increase in expression of Fas and decrease in expression of bcl-2 are involved in the apoptosis of pregnancy-dependent mammary tumor cells after parturition.
Kojima
H
H
Graduate School of Integrated Science, Yokohama City University, Kanazawa-ku, Japan.
Fukazawa
Y
Y
Sato
T
T
Enari
M
M
Matsuzawa
A
A
Tsunoda
S
S
Nagasawa
H
H
Ohta
Y
Y
Iguchi
T
T
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D053938:DNA Fragmentation; D004273:DNA, Neoplasm; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D015674:Mammary Neoplasms, Animal / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D051379:Mice; D009365:Neoplasm Regression, Spontaneous / Q000235:genetics; D009368:Neoplasm Transplantation; D011247:Pregnancy; D011252:Pregnancy Complications, Neoplastic / Q000473:pathology / Q000503:physiopathology*; D012333:RNA, Messenger / Q000032:analysis
D004273:DNA, Neoplasm; D012333:RNA, Messenger