Laboratory of Oncology, IRCCS "Casa Sollievo della Sofferenza" Hospital, San Giovanni Rotondo, Foggia, Italy.
Cell Oncol (Dordr). 2011 Oct;34(5):435-41. doi: 10.1007/s13402-011-0025-9. Epub 2011 Apr 19.
Somatostatin (SS) acts as a universal endocrine off-switch, and also inhibits the growth of neuroendocrine tumours through its specific receptors (SSTRs). Somatostatin receptors are G-protein-coupled receptors, which are encoded by five separate genes (SSTR1-5). Short peptide analogues demonstrate specific binding only for the subgroup consisting of SSTR2a, SSTR3 and SSTR5. Moreover, previous studies reported that expression of mRNA for SSTR2a correlated with therapeutic outcome in patients with carcinoid tumours treated with somatostatin analogs.
To develop and apply a Real Time Quantitative PCR technique (RT-qPCR) to compare and contrast the mRNA levels of SSTR2a, SSTR3 and SSTR5 in Neuroendocrine Lung Cancer affected patients.
Peripheral blood samples from 21 neuroendocrine lung cancer affected patients (14 SCLC, 6 LC and 1 LCNEC) subjected to scintigraphy with (111)In-DTPA-D-Phe(1)-octreotide (OctreoScan) and 24 healthy blood donors were investigated by RT-qPCR. mRNA levels for SSTR2a, SSTR3 and SSTR5 were measured in peripheral blood samples with a relative quantification method using plasmid dilutions as calibration curves and GAPDH as reference gene.
A statistically significant increase in target genes/GAPDH copy number ratio was found for SSTR2a (median 38; IQR 22-141) and SSTR5 (median 51; IQR 19-499) in neuroendocrine lung cancer affected patients as compared with samples from healthy blood donors (P ≤ 0.0003 and P ≤ 0.0005). Since low levels of expression were detected in the control group for all three genes, optimal cut-off values were assessed using ROC curve analyses and were equal to 9.05 for SSTR2a and 16.97 for SSTR5. These cut off values resulted in a sensitivity of 86% (95%IC 65-95) for both markers and a specificity of 83% (95%IC 64-93%) and 79% (95%IC 60-91%) for SSTR2a and SSTR5 respectively. Comparison between OctreoScan results and RT-qPCR analysis demonstrated agreement in 76% of the cases.
Our results suggest that SSTR2a and SSTR5 mRNAs are detectable in peripheral blood of neuroendocrine lung cancer affected patients using real-time quantitative PCR, with a good agreement with OctreoScan. The high sensitivity of this non-invasive molecular technique suggests that this method could represent a useful tool in the clinical management of neuroendocrine lung cancers.
生长抑素（SS）作为一种通用的内分泌关闭开关，通过其特定受体（SSTRs）抑制神经内分泌肿瘤的生长。生长抑素受体是 G 蛋白偶联受体，由五个独立的基因（SSTR1-5）编码。短肽类似物仅对包含 SSTR2a、SSTR3 和 SSTR5 的亚组表现出特异性结合。此外，先前的研究报告称，在接受生长抑素类似物治疗的类癌肿瘤患者中，SSTR2a mRNA 的表达与治疗结果相关。
开发并应用实时定量 PCR 技术（RT-qPCR）比较和对比受神经内分泌肺癌影响的患者 SSTR2a、SSTR3 和 SSTR5 的 mRNA 水平。
对 21 名受神经内分泌肺癌影响的患者（14 名 SCLC、6 名 LC 和 1 名 LCNEC）进行放射性核素扫描（111In-DTPA-D-Phe（1）-octreotide（OctreoScan）），并对 24 名健康献血者进行研究。通过 RT-qPCR 使用质粒稀释作为校准曲线并以 GAPDH 作为参考基因，以相对定量方法测量外周血样本中的 SSTR2a、SSTR3 和 SSTR5 的 mRNA 水平。
与健康献血者的样本相比，受神经内分泌肺癌影响的患者的 SSTR2a（中位数 38；IQR 22-141）和 SSTR5（中位数 51；IQR 19-499）的靶基因/GAPDH 拷贝数比值有统计学显著增加（P ≤ 0.0003 和 P ≤ 0.0005）。由于在对照组中所有三个基因的表达水平都很低，因此使用 ROC 曲线分析评估了最佳截断值，分别等于 SSTR2a 的 9.05 和 SSTR5 的 16.97。这些截断值导致两种标志物的灵敏度均为 86%（95%CI 65-95），SSTR2a 和 SSTR5 的特异性分别为 83%（95%CI 64-93%）和 79%（95%CI 60-91%）。奥曲肽扫描结果与 RT-qPCR 分析之间的比较表明，76%的病例存在一致性。
我们的结果表明，使用实时定量 PCR 可以在外周血中检测到受神经内分泌肺癌影响的患者的 SSTR2a 和 SSTR5 mRNA，与 OctreoScan 具有良好的一致性。这种非侵入性分子技术的高灵敏度表明，该方法可能是神经内分泌肺癌临床管理的有用工具。
