Protective effects of pregnancy and lactation against N-methyl-N-nitrosourea-induced mammary carcinomas in female Lewis rats.
Protective effects of pregnancy and lactation against N-methyl-N-nitrosourea-induced mammary carcinomas in female Lewis rats.
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妊娠和哺乳期对雌性 Lewis 大鼠 N-甲基-N-亚硝基脲诱发乳腺癌的保护作用。
DOI：
10.1093/carcin/20.4.623
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发表时间：
1999
期刊：
影响因子：
4.7
通讯作者：
Tsubura,A
中科院分区：
文献类型：
--
作者：
Yang,J;Yoshizawa,K;Nandi,S;Tsubura,A
研究了 N-甲基-N-亚硝基脲 (MNU) 治疗前后胎次在预防乳腺癌中的作用。还检查了哺乳对降低乳腺癌发病率的影响。将经产大鼠与相应年龄匹配的处女大鼠（AMV）进行比较。暴露于 MNU 之前的妊娠和哺乳期显着降低了乳腺癌的发病率（22% vs 72%）和每只大鼠的平均乳腺癌数量（0.22 vs 0.86），并显着延长了癌症的潜伏期（247 天 vs 215 天）。 MNU 暴露后的妊娠和哺乳期也显着降低了乳腺癌的发病率（25% vs 94%）和每只大鼠的平均乳腺癌数量（0.25 vs 1.50），并显着延长了潜伏期（240 天 vs 155 天）。哺乳对减少乳腺癌有叠加作用。怀孕抑制了非肿瘤乳腺中雌激素受体（ER）和孕激素受体（PgR）阳性细胞的数量，并降低了细胞增殖率。由于大多数（>76%）的乳腺癌在经产大鼠和 AMV 大鼠中都是激素依赖性的，因此妊娠和哺乳似乎减少了 ER 和/或 PgR 阳性细胞（被认为是激素依赖性癌症的祖细胞），并且它们降低了经产大鼠中肿瘤促进所需的细胞更新，导致乳腺癌产量较低。
The role of parity before and afterN-methyl-N-nitrosourea (MNU) treatment in protection against mammary carcinogenesis was investigated. The effect of lactation on reduction in the incidence of mammary carcinoma was also examined. Parous rats were compared with respective age-matched virgins (AMVs). Pregnancy and lactation prior to MNU exposure significantly reduced both the incidence of mammary carcinoma (22 versus 72%) and the average number of mammary carcinomas per rat (0.22 versus 0.86) and significantly prolonged the latency of the carcinomas (247 versus 215 days). Pregnancy and lactation following MNU exposure also significantly reduced both the incidence of mammary carcinoma (25 versus 94%) and the average number of mammary carcinomas per rat (0.25 versus 1.50) and significantly prolonged the latency (240 versus 155 days). Lactation showed an additive effect on the reduction in mammary cancer. Pregnancy suppressed the number of estrogen receptor (ER)- and progesterone receptor (PgR)-positive cells and lowered the cell proliferation rate in the non-tumoral mammary glands. Since the majority (>76%) of the mammary carcinomas was hormone dependent in both the parous and AMV rats, pregnancy and lactation appear to decrease the ER- and/or PgR-positive cells presumed to be the progenitors of hormone-dependent carcinomas and they lowered the cell turnover necessary for tumor promotion in parous rats, resulting in a lower mammary carcinoma yield.