Effects of retinoic acid on proliferation,apoptosis, cytotoxicity,migration, and invasion of neuroblastoma cells

BACKGROUND: Because of the known property of less aggressiveness of differentiated cells compared to immatured cells all attempts are made to elucidate whether differentiation inducers possibly could be applied for neuroblastoma therapy. We are interested in examining the influence of retinoic acid (RA) on proliferation, apoptosis, cytotoxicity, migration, and invasion in dependence of the differentiation of neuroblastoma cells classified into N-type (SK-N-FI, SH-SY5Y), I-type (SK-PN-DW), and S-type (SK-N-LO, SK-N-MC) cells. PROCEDURE: Neuroblastoma cells were exposed to 10(-5) M RA and 200 ng/ml camptothecin (CAM) (control substance for apoptosis). Proliferation, apoptosis, and cytotoxicity were quantified by photometric assays. The influence on migration and invasion of neuroblastoma cells was examined by a scratch-test and by the measurement of the invasion through matrigel coated chamber inserts. RESULTS: In general, RA treatment induced proliferation inhibition predominantly in the cell lines SK-PN-DW (16%, P < 0.05) and SK-N-MC (8%, (P < 0.001), respectively. In the N-type cell lines SK-N-FI (P > 0.05) and SH-SY5Y (P < 0.001) no proliferation inhibition was determined conforming with no detection of apoptosis. CAM confirmed its capability to induce apoptosis in the cell lines SH-SY5Y (43.6%, P < 0.05), SK-PN-DW (54.8%, P > 0.05), and SK-N-MC (28.9%, P < 0.0 01) except for SK-N-FI with only 9.3% (P > 0.05), but after 24 hr of treatment. Minor signs of restricted migration were observed, while RA treatment reduced significantly the invasion rate through Matrigel of SK-N-FI to 13.3% (P < 0.01), SH-SY5Y to 19.2% (P < 0.05), SK-N-MC to 27.8% (P < 0.05), and SK-N-LO to 17.7% (P < 0.01). CONCLUSIONS: It is demonstrated that RA treatment can interfere with cell growth and in invasion by inducing neuronal differentiation in N-type and apoptosis in S-type neuroblastoma cell lines.     

熊果酸对神经母细胞瘤细胞增殖凋亡及MYCN表达的影响

目的实验研究熊果酸作用于体外培养的神经母细胞瘤细胞株（SH—SY-5Y）,对肿瘤细胞增殖、凋亡及MYCN基因mRNA表达的影响,探讨熊果酸对儿童神经母细胞瘤的治疗的作用。方法以终浓度为4uM／L、8uM／L、12uM／L的熊果酸作用于神经母细胞瘤细胞SH—SY-5Y,WST-1法检测SH—SY-5Y细胞增殖情况,流式细胞术检测SH—SY-5Y细胞凋亡情况,采用RealtimePCR方法检测MYCNmRNA的表达情况。结果熊果酸对SH—SY-5Y细胞增殖的抑制呈明显的剂量、时间依赖性,随剂量的增加,作用时间的延长,抑制效果逐渐加强;熊果酸对SHSY-5Y细胞凋亡的促进呈明显的剂量依赖性,随剂量的增加,促进凋亡效果逐渐加强;熊果酸对SH—SY-5Y细胞MYCN表达有抑制作用并有明显的剂量依赖性,随剂量的增加,抑制效果逐渐加强。12uM／L作用72h后神经母细胞瘤细胞增殖抑制效率达98．3％,MYCN基因mRNA表达抑制率达52．37％。结论应用熊果酸在体外环境作用SH—SY-5Y细胞,可以有效抑制该细胞的增殖、促进细胞凋亡、抑制原癌基因MYCNmRNA的表达。     

神经母细胞瘤的凋亡研究

研究临床神经母细胞瘤凋亡情况,了解其与预后的关系。方法取神经母细胞瘤石腊切片,运用原位DNA末端标记法,检测凋亡细胞,计算凋亡细胞占肿瘤细胞百分比,求得凋亡指数。结果预后好的神经母细胞瘤大于预后差的神经母细胞瘤的凋亡指数。若凋亡指数大于9％,提示自发性消退。结论凋亡指数对神经母细胞瘤判断预后、指导治疗有重要价值。     

Hypercalcemia and osteoblastic lesions induced by 13‐Cis‐retinoic acid mimicking relapsed neuroblastoma

A 6‐year‐old male diagnosed with extensive neuroblastoma was treated with chemotherapy, surgery, autotransplantation, and radiotherapy. He was then enrolled on a study to assess the monoclonal antibody Ch14.18 (anti‐GD2) with 13 cis‐retinoic acid. 13‐cis‐retinoic acid therapy caused severe bone pain and hypercalcemia. Bone scans showed multiple osteoblastic lesions suggesting recurrent disease however MIBG scans were negative. Serum markers of bone turnover were increased and the patient required pamidronate therapy to treat persistent hypercalcemia. Retinoic acid toxicity needs to be considered in the differential of painful osteoblastic lesions and/or hypercalcemia. MIBG scans can assist in differentiating from recurrent disease. Pediatr Blood Cancer 2009;53:666–668. © 2009 Wiley‐Liss, Inc.     

Hypercalcemia and 13-cis-retinoic acid in post-consolidation therapy of neuroblastoma

We report 19 episodes of hypercalcemia in three children treated with 13-cis-retinoic acid (13-cis-RA) as a post-consolidation therapy for high-risk neuroblastoma. There was no concomitant overload in 13-cis-RA blood levels. Blood calcium fell after arrest of 13-cis-RA intake. Half dosage retinoid treatment resumption did not prevent the recurrence of hypercalcemia. Concomitant biological values showed massive bone resorption. Hence, hypercalcemia seemed not secondary to 13-cis-RA overload but rather to inter-individual variability in its interaction with bone metabolism. Current guidelines in case of hypercalcemia are to reduce 13-cis-RA dosage. Instead we propose to maintain the therapeutic dosage, but to shorten the duration of courses.     

汉防己甲素诱导神经母细胞瘤株TGW凋亡作用的实验研究

目的为评价汉防己甲素(TET)应用于神经母细胞瘤的可能性,应用TET处理人神经母细胞瘤株TGW,观察其作用情况。方法采用MTT比色法观察TET对神经母细胞瘤增生的影响,琼脂凝胶电泳法观察DNA片断化的梯形条带,流式细胞仪观察TET对神经母细胞瘤凋亡水平影响,实时定量PCR法了解Bcl_2家族(Bcl_2,Bcl_XL,Bad,Bax)表达的变化。结果25~0.5μMTET能明显抑制TGW细胞,25μM汉防己甲素作用48h最大抑制率为(95.32±2.46)%;琼脂糖凝胶电泳法观察到25μMTET处理12、24、36、48h后出现典型的凋亡表现;流式细胞仪Annexin及PI双染发现25μMTET孵育24h肿瘤细胞的凋亡率明显上升;实时定量PCR发现25μMTET处理24h后Bax基因表达明显增加。结论汉防己甲素能诱导人神经母细胞瘤株TGW凋亡,上调Bax基因的表达。     

Prevalence of advanced bone age in a cohort of patients who received cis-retinoic acid for high-risk neuroblastoma

In the last decade, 13-cis-retinoic acid (13-cis-RA) has been added to the treatment of patients with high-risk neuroblastoma. In survivors of neuroblastoma, short stature is consistently observed. Causes include growth hormone deficiency and poor growth of irradiated long bones. Within the survivorship program at CHOP, we have observed that a number of these patients also have advanced bone ages. Children treated with 13-cis-RA are at risk for advanced bone age that may dramatically impact their linear growth. Ongoing evaluation is necessary to examine the effect of 13-cis-RA on final adult height and to inform clinical practice in this cohort.     

加温诱导人神经母细胞瘤SK-H-SN细胞凋亡的研究

目的：探讨加温对诱导神经母细胞瘤SK－H－SN细胞凋亡的作用及其意义。方法：用三种温度41．5℃、43℃、45℃诱导SK－H－SN细胞凋亡。采用形态学观察，原位缺口末端标记（TUNEL）的方法检测细胞凋亡的结果。结果：加温至41．5℃、43℃均可诱导SK－H－SN细胞凋亡，且凋亡率随温度的升高而升高。45℃时凋亡率下降，但出现大量的坏死细胞，结论：加温可诱导SK－H－SN细胞凋亡，在一定范围内，凋亡率和温度呈正相关，热疗可能为神经母细胞瘤的治疗提供新的手段。     

MiR-483-3P下调RIOK3蛋白表达促进神经母细胞瘤的增殖和迁移

目的探讨microRNA-483-3P(miR-483-3P)对神经母细胞瘤细胞的增殖、侵袭及迁移能力的影响,预测并验证miR-483-3P的靶基因及其对靶基因的影响。方法 miRNA微阵列芯片结果发现miR-483-3P在神经母细胞瘤中表达上调,差异倍数显著,并居于差异表达miRNA的首位。利用阳离子脂质体LipofectamineTM2000将化学合成的miR-483-3P inhibitor、miR-483-3P inhibitor的阴性对照序列分别瞬时转染人人神经母细胞瘤SH-SY-5Y细胞株中,RT-qPCR技术检测各组中miR-483-3P的表达水平,CCK-8法检测各组癌细胞的增殖情况,Transwell小室实验检测各组癌细胞的体外侵袭和迁移能力。利用生物信息学软件预测miR-483-3P的靶基因并用荧光素酶报告基因检测实验、Western blot实验加以验证。结果与癌旁正常组织相比,miR-483-3P在神经母细胞瘤中高表达(P0.01);与阴性对照组相比,癌细胞转染miR-483-3P inhibitor后,miR-483-3P表达显著下调(P0.01),细胞的增殖情况和体外迁移能力均降低(P0.05)。生物信息学软件预测出RIOK3是miR-483-3P的靶基因之一,当细胞转染了miR-483-3P inhibitor后荧光酶活性升高(P0.01)。与阴性对照组相比,当细胞转染了miR-483-3P inhibitor后在蛋白质水平RIOK3表达升高(P0.01)。结论.RIOK3是miR-483-3P的靶基因之一,miR-483-3P能下调RIOK3的表达并显著促进神经母细胞瘤细胞的增殖和体外迁移。     

A phase 2 trial of all-trans-retinoic acid in combination with interferon-alpha2a in children with recurrent neuroblastoma or Wilms tumor: A Pediatric Oncology Branch, NCI and Children's Oncology Group Study

BACKGROUND: The combination of the antiproliferative and differentiation-inducing effects of retinoids together with the antiproliferative, immunostimulatory, and differentiation-potentiating effects of interferon-alpha (IFN-alpha) were the basis for the development of this combination in pediatric patients with refractory neuroblastoma or Wilms tumor. PROCEDURE: A phase 2 trial of all-trans-retinoic acid (ATRA), administered orally at a dose of 90 mg/m(2)/day in three divided doses for 3 consecutive days per week, and IFN-alpha2a, administered subcutaneously daily at a dose of 3 x 10(6) U/m(2)/day for 5 consecutive days per week, in 4 week cycles was performed. A two-stage design was used for each disease stratum. RESULTS: Seventeen patients (16 evaluable) with neuroblastoma, median age 9 years, and 15 patients (14 evaluable) with Wilms tumor, median age 6 years, were enrolled. Overall, the combination was well tolerated, with headache being the most common toxicity observed. There were no complete or partial responses. The median number of cycles administered was 1 (range 1-9). Four patients with neuroblastoma had stable disease for 12 or more weeks. CONCLUSIONS: The combination of ATRA and IFN-alpha2a was inactive in children with relapsed or refractory neuroblastoma and Wilms tumor. The lack of activity with this combination in children with refractory neuroblastoma is similar to the disappointing phase 2 results of single agent 13-cis-retinoic-acid (13cRA) and does not support further development of ATRA for children with relapsed neuroblastoma.     

全反视黄酸对哮喘大鼠气道反应性和气道重塑的影响

目的：观察全反视黄酸(ATRA)对哮喘大鼠气道反应性、气道重塑和肺组织基质金属蛋白酶-9(MMP-9)表达的影响。方法：40只大鼠随机分为5组,每组8只：盐水组、模型组、ATRA组、棉籽油组和布地奈德（BUD）组。后4组经卵清蛋白（OVA）致敏14 d后激发6周,构建大鼠慢性哮喘模型。ATRA组、棉籽油组和BUD组每次激发前分别给予ATRA 50 μg/kg、棉籽油1 mL和BUD 0.32 mg/kg。5组大鼠行气道反应性检测,并测定肺组织MMP-9表达和气道重塑情况。结果：ATRA干预组的气道反应性与盐水组比较差异无统计学意义（P＞0.05）,MMP-9表达高于盐水组,差异具有统计学意义（P＜0.05）。ATRA干预组的气道反应性和MMP-9表达均明显低于模型组,气道重塑改变减轻,差异具有统计学意义（P＜0.05）。结论：早期预防性ATRA干预通过减少肺组织MMP-9表达,可在一定程度上减轻哮喘大鼠的气道重塑和气道高反应性。     

小剂量维甲酸诱导对神经母细胞瘤耐药的影响

目的探讨小剂量维甲酸诱导对神经母细胞瘤(NB)化疗耐药的影响。方法选择人NB细胞株SH SY5Y,用RT PCR方法检测小剂量全反式维甲酸(ATRA)作用下TrkB mRNA水平;通过四甲基偶氮蓝比色(MTT)法及流式细胞仪(FCM)检测ATRA诱导前后顺铂对人NB细胞株SH SY5Y的生长及凋亡的影响。结果SH SY5Y中未检测到TrkB mRNA表达,用1、10、100nM/LATRA诱导5d后可检测到TrkB mRNA表达,且随ATRA浓度增加TrkB mRNA水平逐渐升高。100nM/LATRA诱导7d,TrkB mRNA的相对比值与诱导5d比差异无显著性意义(P>0.05);MTT分析显示:BDNF+顺铂组(无TrkB表达)、ATRA+顺铂组(无BDNF刺激)细胞存活率同单用顺铂组比较无显著性差异(P>0.05);10nM/LATRA+BDNF+顺铂组NB细胞存活率明显高于单用顺铂组(P<0.01);FCM分析显示:ATRA+BDNF+顺铂组NB细胞凋亡率明显低于单用顺铂组(P<0.01)。结论存在BDNF的条件下,小剂量ATRA能阻断顺铂对SH SY5Y的细胞毒性作用,从而使SY5Y细胞对化疗耐药。     

全反式视黄酸诱导小鼠骨髓基质细胞后视黄酸受体和造血因子表达的研究

目的 研究维生素Ａ（ＶＡ）对造血调控的机制。方法 体外培养小鼠骨髓基质细胞（ＢＭＳＣ）和造血祖细胞,免疫组化ＳＰ法检测全反式视黄酸（ＡＴＲＡ）体外诱导小鼠ＢＭＳＣ后视黄酸受体（ＲＡＲｓ）和ＧＭ－ＣＳＦ蛋白的表达以及生物因子活性检测。结果 １．ＡＴＲＡ处理的小鼠ＢＭＳＣ上清淮能显著促进红系祖细胞的增殖（Ｐ〈０．０１）。２．ＲＡＲｓ在实验组和对照组持续表达,ＡＴＲＡ对其表达无影响。３．ＡＴＲＡ诱导小鼠     

全反式维A酸对缺氧性肾小管上皮细胞Prohibitin1和Prohibitin2表达的影响

目的 探讨全反式维A酸(ATRA)对缺氧性肾小管上皮细胞(RTEC) Prohibitin1(PHB1)和Prohibitin2(PHB2)表达的影响.方法 购自上海生物细胞库的大鼠近端肾小管上皮细胞株NRK-52E,采用混有胎牛血清和双抗的培养基(100 mL培养基中加5 mL胎牛血清和1 mL双抗)在37℃、50 mL/L二氧化碳的培养箱中培养.传代3次后分为正常组、模型组和ATRA干预组.正常组细胞不做任何处理,模型组细胞置于真空罐中,负压吸引器吸尽残余空气,充人缺氧气体(950 mL/L氮气和50 mL/L二氧化碳)密封建立缺氧性RTEC损伤模型,ATRA干预组细胞中加入0.1 μmol/L ATRA后参照模型组的方法进行缺氧.于缺氧24 h、36 h采用实时荧光定量PCR法测定各组NRK-52E细胞PHB1、PHB2、转化生长因子-β1(TGF-β1)的mRNA表达,Western blot法检测各组NRK-52E细胞PHB1、PHB2、TGF-β1的蛋白表达.结果 1.与正常组比较,模型组和ATRA干预组2个时间点NRK-52E细胞的PHB1和PHB2的蛋白表达量及其mRNA表达量均显著下降(P均＜0.05),缺氧时间越长,表达量越低;与模型组比较,ATRA干预组2个时间点NRK-52E细胞的PHB1和PHB2的蛋白表达量及其mRNA表达量均显著上升(P均＜0.05).2.与正常组比较,模型组和ATRA干预组2个时间点NRK-52E细胞的TGF-β1的蛋白表达量及其mRNA表达量均显著上升(P均＜0.05),缺氧时间越长,表达量越高;与模型组比较,ATRA干预组2个时间点NRK-52E细胞的TGF-β1的蛋白表达量及其mRNA表达量均显著下降(P均＜0.05).结论 ATRA可显著增强缺氧性RTEC中PHB1和PHB2蛋白表达量及其mRNA表达量,可能对缺氧性RTEC有保护作用.     

内源性一氧化碳对培养的肺动脉平滑肌细胞增殖与凋亡的调节

目的 探讨内源性一氧化碳（CO）对低氧性肺血管平滑肌细胞（PASMC）增殖与凋亡的影响及机制。方法 体外培养Wistar大鼠PASMC,进行低氧并予以血红素氧合酶抑制剂卟啉锌－9（zinc protoporphyrin IX,ZnPP-9)处理,分为常氧12h组（N1组）、常氧24h组（N2组）、低氧12h组（H1组）、低氧24h组（H2组）、低氧12h ZnPP组（H1＋ZnPP组）、低氧24h ZnPP组（H2＋ZnPP组）,采用流式细胞术、免疫细胞化学方法检测PASMC增殖与凋亡情况。结果 1．碳氧血红蛋白（HbCO)检测：采用双波长法测定细胞培养液中HbCO的吸光度,用以代替培养液中CO的相对含量。低氧12h培养液中HbCO较常氧时显著增高（P＜0．01）,至24h恢复至常氧水平（P＞0．05）;而低氧同时进行干预,H1＋ZnPP及H2＋ZnPP两组HbCO水平均下降,且明显低于单纯低氧组（P＜0．01）,两组与常氧组相比亦有差异（P＜0．001）。2．流式细胞仪检测PASMC增殖指数（PI）与凋亡指数（AI）：H1组PI较N1组下降（P＜0．01）,H2组则较N2组增高（P＜0．001）;H1＋ZnPP组较H1组PI显著增高（P＜0．001）,H2＋ZnPP组与H2组比则无明显变化（P＞0．05）;H1组AI低于H2组（P＜0．01）,H1＋ZnPP组AI高于H1组（P＜0．001）,H2＋ZnPP组则低于H2组（P＜0．001）。3．PCNA免疫细胞化学染色,H1组及H2组PASMC细胞核阳性反应颗粒分别按N1及N2组明显增加（P分别＜0．01及P＜0．001）,H1＋ZnPP组及H2＋ZnPP组分别较H1及H2组增强（P＜0．01）。4．Caspase 3免疫细胞化学：H2组与H1组比胞浆着色增强（P＜0．05）,ZnPP处理12h及24h分别较H1及H2减弱（P＜0．05）。5．NF－κK免疫细胞化学：H1及H2组核染色分别较N1及N2组增强（P＜0．001）,而H1＋ZnPP组及H2＋ZnPP组则又分别较H1、H2组阳性核表达增多（P＜0．01）。结论 1．低氧12h内源性CO对PASMC增殖抑制作用显著,对凋亡可能无直接影响;低氧24h CO促进PASMC凋亡作用明显,而对增殖的影响不显著。2．NF－κB可能参与了内源性CO抑制PASMC增殖的调控机制。     

选择性COX-2抑制剂对Raji细胞增殖、凋亡及Survivin表达的影响

目的 探讨选择性COX-2抑制剂塞来昔布（celecoxib）对恶性淋巴瘤细胞的作用及其抗肿瘤的非COX-2依赖性途径之可能机制。方法 体外培养人Burkitt淋巴瘤Raji细胞,用不同浓度的塞来昔布进行干预。应用MTT比色法检测Raji细胞生长情况;流式细胞术分析塞来昔布对Raji细胞周期的影响并检测细胞凋亡及Survivin蛋白在细胞中的表达情况;应用RT-PCR法检测Raji细胞中Survivin mRNA的表达水平。结果 塞来昔布对Raji细胞生长具有抑制作用,且在12.5-150 μmol/L范围内呈时间、剂量依赖性;流式细胞术检测出典型的凋亡峰,凋亡率（9.20&#177;0.19）%-（44.63&#177;1.34）%;塞来昔布使Raji细胞G0/G1期细胞数增多,S和G2/M期细胞数减少,凋亡率和细胞周期分布呈量效依赖关系;塞来昔布下调Raji细胞中Survivin蛋白和Survivin mRNA的表达。结论 塞来昔布抑制Raji细胞增殖、诱导其凋亡可能与阻滞细胞周期和下调Survivin表达有关,这可能是其抗肿瘤的非COX-2依赖性途径之机制。     

硫化氢对自发性高血压大鼠主动脉平滑肌细胞增殖与凋亡的影响

目的 探讨气体分子硫化氢(H2S)对自发性高血压大鼠主动脉平滑肌细胞增殖与凋亡的影响及其作用机制。方法 4周龄雄性自发性高血压(SHR)鼠及韦斯达-克陀鼠(WKY)各自随机分为对照组、 硫氢化钠(NaHS)组、 PPG组，5周后应用免疫组织化学方法检测细胞增殖核抗原(PCNA)、NF-κB、Bcl2、Fas、Fas、caspase-3的表达水平，应用原位缺口末端标记法(TUNEL)检测细胞凋亡情况。结果 SHR对照组大鼠较WKY对照组大鼠增殖指数(PI)及凋亡指数(AI)均增高；SHR NaHS组大鼠较SHR对照组大鼠PI降低、AI增高；SHR PPG组大鼠AI降低。WKY PPG组大鼠较WKY对照组大鼠PI增高。SHR对照组大鼠主动脉Bcl-2及NF-κB表达均较WKY对照组降低，caspase-3表达升高。SHR NaHS组大鼠主动脉Bcl-2及NF-κB水平低于SHR对照组，而SHR PPG组大鼠主动脉Bcl-2及NF—κB水平高于SHR对照组。SHR NaHS组大鼠主动脉caspase-3水平较SHR对照组高，而SHR PPG组大鼠主动脉caspase-3水平低于SHR对照组。WKY NaHS组及WKY PPG组大鼠主动脉平滑肌细胞的各项凋亡相关因子表达与WKY对照组相似。H2S供体或PPG干预组Fas水平与相应对照组相比无明显改变。结论 H2S可抑制平滑肌细胞增殖，并可能通过下调凋亡抑制因子Bcl-2及NF-κB水平，最终激活效应因子caspase-3而促进血管平滑肌细胞凋亡，缓解自发性高血压血管结构重建。     

地塞米松、维甲酸对大鼠肺发育的影响及与胰岛素样生长因子关系

目的探索地塞米松(Dex)、维甲酸(RA)对大鼠肺发育的影响及其与胰岛素样生长因子(IGF)_Ⅰ、(IGF)_Ⅱ的关系。方法将80只SD孕鼠分为4组,即对照组(A组)、Dex1组(B组)、Dex2组(C组)、RA组(D组)。A、B、D组于孕18～20d分别皮下注射生理盐水、Dex,腹腔注射RA,C组于生后1～3d皮下注射Dex。各组于孕18、20、21d(C组孕期不取)、生后1、3、5、7、10、14、21d取肺标本作病理学检查、辐射状肺泡计数(RAC)、IGF_Ⅰ、IGF_Ⅱ多肽或mRNA之肺表达强度。结果①形态学及肺表达:B、C组早期肺泡发育提前(数目多,壁薄),晚期则腔大数少;IGF_Ⅰ主要表达于肺胞分隔期(生后4～10d),A、D组等肺泡发育时,IGF_Ⅰ呈强阳性表达,其他各组或时间点则呈弱阳性或阴性表达;IGF_Ⅱ的表达主要见于出生前支气管,小血管等管道组织,受Dex等影响较小。②Westernblot结果:IGF_Ⅰ多肽的表达:A组生后5～7d达高峰,随后渐降低;B组孕20d～生后3d,各时间点强度明显高于A组(P<0.01),以后均低于A组(P<0.01);C组晚期强度明显低于A组(P<0.01);D组各时间点浓度明显高于A组(P<0.01)。IGF_Ⅱ多肽的表达:各组孕18d最高,随后渐降低直至微量。③RT_PCR结果:IGF_Ⅰ、IGF_ⅡmRNA表达的强度变化与各自的肽浓度变化相似。结论IGF_Ⅰ、IGF_Ⅱ与肺发育过程有密切关系,IGF_