Seethalakshmi L, Mitra S P, Dobner P R, Menon M, Carraway R E
Department of Physiology, University of Massachusetts Medical Center, Worcester 01655, USA.
Prostate. 1997 May 15;31(3):183-92. doi: 10.1002/(sici)1097-0045(19970515)31:3<183::aid-pros7>3.0.co;2-m.
Neurotensin (NT), a neuroendocrine peptide, exerts trophic effects in vivo and stimulates growth of some tumor cells in vitro. Androgen-sensitive prostate cells derived from lymph node carcinoma of the prostate (LNCaP) secrete NT and exhibit growth responses to NT. This study examines NT secretion, NT receptor and NT-growth responses in androgen-independent prostatic carcinoma (PC3) cells derived from prostate adenocarcinoma metastatic to bone.
Binding of 125I-NT to PC3 membranes was studied by filtration. NT was measured by RIA. Reverse transcriptase polymerase chain reaction (RT-PCR) was used for NT and NT receptor mRNA. Growth was measured as 3H-thymidine incorporation into DNA.
Scatchard analyses gave two binding components (Kd1 = 40 pM and Kd2 = 300 pM) in equal amounts (15-30 x 10(3) sites/cell). The bioactive region of NT was essential and the specific, non-peptide NT antagonist, SR48692, inhibited (IC50 = 3 nM). GTP analogs, sodium ion and SH-directed alkylating agents also inhibited. Glutaraldehyde crosslinking labeled two substances (M(r) of 23 and 46 kDa). RT-PCR indicated robust expression of authentic NT receptor but little for NT precursor. NT was stable in PC3 cultures but it was not found in cells or conditioned media. Incubated with PC3 cells, NT exhibited a mitogenic effect with bell-shaped dose-response and maximum at 100 pM NT.
PC3 cells expressed genuine NT receptors and generated growth responses to physiologic levels of NT which were blocked by SR48692. If NT contributes to the survival of prostate tumor cells upon androgen deprivation therapy, NT antagonists might be useful agents in further treatment.
神经降压素（NT）是一种神经内分泌肽，在体内发挥营养作用，并在体外刺激某些肿瘤细胞生长。源自前列腺淋巴结癌（LNCaP）的雄激素敏感前列腺细胞分泌NT，并对NT表现出生长反应。本研究检测了源自转移至骨的前列腺腺癌的雄激素非依赖性前列腺癌细胞（PC3）中的NT分泌、NT受体和NT生长反应。
通过过滤研究125I-NT与PC3细胞膜的结合。用放射免疫分析法（RIA）测定NT。逆转录聚合酶链反应（RT-PCR）用于检测NT和NT受体mRNA。通过测定3H-胸腺嘧啶掺入DNA来检测细胞生长。
Scatchard分析显示有两个等量的结合成分（Kd1 = 40 pM和Kd2 = 300 pM）（15 - 30×10(3)个位点/细胞）。NT的生物活性区域至关重要，特异性非肽类NT拮抗剂SR48692具有抑制作用（IC50 = 3 nM）。GTP类似物、钠离子和SH定向烷基化剂也有抑制作用。戊二醛交联标记了两种物质（分子量分别为23 kDa和46 kDa）。RT-PCR表明有活性的NT受体有较强表达，但NT前体表达较少。NT在PC3培养物中稳定，但在细胞或条件培养基中未检测到。与PC3细胞一起孵育时，NT表现出促有丝分裂作用，剂量反应呈钟形，在100 pM NT时达到最大值。
PC3细胞表达真正的NT受体，并对生理水平的NT产生生长反应，而这种反应被SR48692阻断。如果NT在雄激素剥夺治疗中有助于前列腺肿瘤细胞的存活，NT拮抗剂可能是进一步治疗的有用药物。
