Shen R, Dorai T, Szaboles M, Katz A E, Olsson C A, Buttyan R
Molecular Urology Laboratory of the Department of Urology, and the Department of Pathology, Columbia University College of Physicians and Surgeons, New York, NY, USA.
Urol Oncol. 1997 Mar-Apr;3(2):67-75. doi: 10.1016/s1078-1439(97)00039-2.
Neuroendocrine (NE) cells are enigmatically found in association with human prostate cancers and their numbers are reported to increase in advanced and hormoneresistant tumors. The origin of this cell type and the reason for their appearance in prostate tumors remains unresolved. Previously, Bang et al. (Proc Natl Acad Sci USA 1994;91:5330) reported that dibutyryl adenosine 3',5'-cyclic phosphate (db-cAMP), an agent that upregulates intracellular cAMP, was able to induce a NE cell-like phenotype of cultured human prostate cancer cells, including the androgen-sensitive LNCaP line. Here we report that chronic incubation of LNCaP cells in a medium containing 10% charcoal-stripped fetal bovine serum (CSFBS) likewise induces NE differentiation of these cells. Within 5 days of switching low density cultures of LNCaP cells to this modified medium, the cells growth arrest and acquire an altered morphology with numerous cytoplasmic secretory granules and elongated processes that resemble cultured neurons. This morphology predominates at 10 days with complete transformation seen by 20 days of culture. Electron microscopic analysis of sections of CS-FBS maintained cells showed the presence of abundant dense core secretory granules characteristic of NE cells. Immunohistochemical staining identified the upregulation of the expression of NE markers bombesin, neuron-specific enolase, and S-100 in this modified culture medium. Once established, the NE cell-like phenotype was found to be reversible upon replacement with a medium containing unmodified fetal bovine serum, but not by direct supplementation of CS-FBS medium with dihydrotestosterone (DHT) (I nM). DHT supplementation did, however, suppress the development of the NE cell-like phenotype when it was present at the initiation of exposure to CS-FBS medium. In contrast to db-cAMP treatment, which did not affect prostate specific antigen (PSA) or androgen receptor (AR) expression of LNCaP cells, NE-differentiated LNCaP cells derived in this hormone-deficient medium showed marked downregulation of PSA and AR expression. These in vitro results further support the concept that prostate cancer cells can tranform in vivo to cells with a NE phenotype and suggest that this transformation might be accelerated in patients by certain therapies for prostate cancer.
神经内分泌（NE）细胞神秘地与人类前列腺癌相关联，据报道其数量在晚期和激素抵抗性肿瘤中会增加。这种细胞类型的起源及其在前列腺肿瘤中出现的原因仍未明确。此前，Bang等人（《美国国家科学院院刊》1994年；91:5330）报道，二丁酰腺苷3'，5'-环磷酸酯（db-cAMP），一种上调细胞内cAMP的物质，能够诱导培养的人类前列腺癌细胞呈现NE细胞样表型，包括雄激素敏感的LNCaP细胞系。在此我们报道，将LNCaP细胞在含有10%活性炭处理胎牛血清（CSFBS）的培养基中长时间培养同样能诱导这些细胞发生NE分化。将低密度培养的LNCaP细胞转入这种改良培养基5天内，细胞生长停滞并获得改变的形态，具有大量细胞质分泌颗粒和类似培养神经元的细长突起。这种形态在10天时占主导，培养20天时可见完全转变。对CS-FBS培养的细胞切片进行电子显微镜分析显示存在大量典型的NE细胞致密核心分泌颗粒。免疫组织化学染色鉴定出在这种改良培养基中NE标志物蛙皮素、神经元特异性烯醇化酶和S-100的表达上调。一旦形成，发现NE细胞样表型在用含有未处理胎牛血清的培养基替换后是可逆的，但用二氢睾酮（DHT）（1 nM）直接补充CS-FBS培养基则不能使其逆转。然而，在开始接触CS-FBS培养基时存在DHT可抑制NE细胞样表型的发展。与不影响LNCaP细胞前列腺特异性抗原（PSA）或雄激素受体（AR）表达的db-cAMP处理不同，在这种激素缺乏培养基中诱导产生的NE分化LNCaP细胞显示PSA和AR表达明显下调。这些体外结果进一步支持了前列腺癌细胞可在体内转变为具有NE表型细胞的概念，并表明这种转变在前列腺癌患者中可能会因某些前列腺癌治疗而加速。
