The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Australia.
Am J Physiol Lung Cell Mol Physiol. 2011 Oct;301(4):L478-89. doi: 10.1152/ajplung.00063.2011. Epub 2011 Jul 8.
The factors regulating growth of the developing lung are poorly understood, although the degree of fetal lung expansion is critical. The oncogene Trop2 (trophoblast antigen 2) is upregulated during accelerated fetal lung growth, and we hypothesized that it may regulate normal fetal lung growth. We investigated Trop2 expression in the fetal and neonatal sheep lung during accelerated and delayed lung growth induced by alterations in fetal lung expansion, as well as in response to glucocorticoids. Trop2 expression was measured using real-time PCR and localized spatially using in situ hybridization and immunofluorescence. During normal lung development, Trop2 expression was higher at 90 days gestational age (GA; 4.0 ± 0.8) than at 128 days GA (1.0 ± 0.1), decreased to 0.5 ± 0.1 at 142 days GA (full term ∼147 days GA), and was positively correlated to lung cell proliferation rates (r = 0.953, P < 0.005). Trop2 expression was regulated by fetal lung expansion, but not by glucocorticoids. It was increased nearly threefold by 36 h of increased fetal lung expansion (P < 0.05) and was reduced to ∼55% of control levels by reduced fetal lung expansion (P < 0.05). Trop2 expression was associated with lung cell proliferation during normal and altered lung growth, and the TROP2 protein colocalized with Ki-67-positive cells in the fetal lung. TROP2 was predominantly localized to fibroblasts and type II alveolar epithelial cells. Trop2 small interfering RNA decreased Trop2 expression by ∼75% in cultured fetal rat lung fibroblasts and decreased their proliferation by ∼50%. Cell viability was not affected. This study demonstrates that TROP2 regulates lung cell proliferation during development.
调控肺发育的因素知之甚少，尽管胎儿肺扩张的程度至关重要。癌基因 Trop2（滋养细胞抗原 2）在胎儿肺加速生长过程中上调，我们假设它可能调控正常胎儿肺生长。我们研究了在改变胎儿肺扩张诱导的胎儿和新生羊肺加速和延迟生长期间以及对糖皮质激素反应时，Trop2 在胎儿和新生羊肺中的表达。使用实时 PCR 测量 Trop2 表达，并通过原位杂交和免疫荧光定位空间表达。在正常肺发育过程中，Trop2 表达在 90 天胎龄（GA；4.0 ± 0.8）时高于 128 天 GA（1.0 ± 0.1），在 142 天 GA 时降低至 0.5 ± 0.1（足月约 147 天 GA），并且与肺细胞增殖率呈正相关（r = 0.953，P < 0.005）。Trop2 表达受胎儿肺扩张调节，但不受糖皮质激素调节。增加胎儿肺扩张 36 小时可使其表达增加近三倍（P < 0.05），减少胎儿肺扩张可使其表达降低至对照水平的约 55%（P < 0.05）。Trop2 表达与正常和改变的肺生长期间的肺细胞增殖有关，并且 TROP2 蛋白与胎儿肺中的 Ki-67 阳性细胞共定位。Trop2 主要定位于成纤维细胞和 II 型肺泡上皮细胞。Trop2 小干扰 RNA（siRNA）使培养的胎鼠肺成纤维细胞中的 Trop2 表达降低约 75%，并使其增殖降低约 50%。细胞活力不受影响。这项研究表明，TROP2 在发育过程中调控肺细胞增殖。
