Investigations of prostate epithelial stem cells and prostate cancer stem cells

Although both prostate epithelial stem cells and prostate cancer stem cells are implicated in the differentiation of the normal prostate gland and carcinogenesis of prostate cancer, there has, until recently, been little information regarding their biology. This review summarizes the recent advancements in cell biological research including various in vitro culture systems that have offered the characterization and isolation of prostate epithelial stem cells and prostate cancer stem cells. In addition, the stromal niche or microenvironment of stem cells plays an essential role in proliferation and differentiation of normal stem cells. Stroma surrounding cancer cells, which also provide another unique niche, may involve the initiation and development of cancer stem cells. Investigation of stem cells and their microenvironments in the prostate should lead to the elucidation of biological features and the development of novel treatments for prostate cancer.     

Neuroendocrine differentiation of human prostatic primary epithelial cells in vitro

BACKGROUND: Dispersed prostatic neuroendocrine cells are involved in growth regulation of the prostate and are considered to play a role in the pathogenesis of prostate carcinoma and benign prostatic hyperplasia (BPH). They are meant either to be derived from the neural crest during embryogenesis or by direct differentiation of the cells from locally present precursor cells. METHODS: An in vitro model was developed for human prostatic epithelial and neuroendocrine cell differentiation. Minced explants from radical prostatectomies were seeded on collagen I-coated plates. RESULTS: The majority of outgrowing cells were basal cells, positive for cytokeratin markers K 5/14 and CD 44, as determined by confocal laser scanning microscopy. A small fraction of interdispersed single cells expressing c-kit, which is found on pluripotent precursors, was identified by immunofluorescence. From these basal cells, in vitro differentiation of cells with neuroendocrine morphology could be achieved within 3 days. These were at rest, i.e., non-bromodeoxyuridine incorporating cells and characteristically coexpressed K 5/14, K 18, and the neuroendocrine marker chromogranin A. Luminal cells staining for K 8 or 18 were not observed. CONCLUSION: Neuroendocrine differentiation of adult prostatic cells was achieved in vitro, favoring the hypothesis that neuroendocrine cells are derived from peripheral precursor cells. The acceleration of this differentiation pathway may be the reason for the increased presence of neuroendocrine cells in areas of epithelial hyperplasia in BPH.     

Electrophoretic marker of differentiated human prostate secretory epithelial cells

Electrophoretic analysis of primordial human prostate epithelium, glandular secretory epithelium of prostate and other human tissues revealed a marker characteristic of differentiated secretory prostate cells. Being probably neither protein nor lipid in chemical nature, this marker reacted in a peculiar way with Amido Black 10B. The marker was shown to be present in prostatic secretory substance.     

Ultrastructure of the secretion of prostasomes from benign and malignant epithelial cells in the prostate

BACKGROUND: Prostate epithelial cells are producing, among other things, a fluid secretion containing small bodies, the prostasomes. The mechanism of synthesis of the prostasomes is not known in details, neither is it known whether the mode of prostasome production changes at a neoplastic transformation of the prostate cells. Due to the small size of the prostasomes, we have used electron microscopy for evaluating the production and distribution of prostasomes in benign and neoplastic cells of the prostate. METHODS: Benign and neoplastic areas in plastic embedded core biopsy specimens of prostate tissue were identified, and secreting cells were selected. The corresponding areas on the plastic blocks were further processed for examination in the electron microscope. RESULTS: The electron microscopical examination showed that the secretory machinery was similar in both types of tissue. Thus, in both benign and well-differentiated neoplastic cells studied, the formation of storage vesicles in the Golgi areas was similar, the content of the vesicles appeared similar, the structure and distribution of prostasomes were alike, and in both benign and malignant tissue, the secretion in the gland ducts showed the same appearance with many prostasomes. CONCLUSION: We conclude that cells in benign prostate tissue and cells in well-differentiated prostate carcinoma show great similarities in synthesis, storage, and release of prostasomes. However, this does not exclude the presence of other changes, for instance biochemical ones, in the prostasomes.     

Culture of prostatic epithelial cells from ultrasound-guided needle biopsies.

A protocol which was developed for the culture of epithelial cells from radical prostatectomy specimens was slightly modified to permit the culture of cells from ultrasound-guided prostatic needle biopsies. The collagenase digestion step of the standard protocol was omitted, and biopsies were simply minced and allowed to attach to collagen-coated dishes in serum-free medium. Cell outgrowths from biopsies were free of fibroblasts, and expression of keratin, prostate specific antigen, and prostatic acid phosphatase was maintained in vitro. The establishment of a bank of frozen cells from primary cultures permitted repetitive studies with individual cell strains, which could be serially passaged and were capable of clonal growth. The ability to derive cultures from biopsies will facilitate the biological characterization of cells from primary prostate tumors of high malignant grade, which are not commonly available from radical prostatectomy specimens.     

Analysis of somatic cell hybrids derived from normal human prostatic epithelial cells fused with HeLa cells.

Somatic cell hybrids have been instrumental in the recognition of specific chromosomes containing genes capable of suppressing the malignant phenotype. As a first step towards the identification of possible suppressor genes in prostate cells, we created hybrids by fusing normal prostate cells with malignant HeLa cells. Similar to hybrids made with other combinations of normal and malignant cells, the normal phenotype was dominant and the malignant phenotype was suppressed. The phenotype of the nontumorigenic hybrids after injection into nude mice resembled that of normal keratinocyte X HeLa hybrids, and tiny, nonprogressive keratinized nodules were produced. One hybrid clone was tumorigenic, possible due to the loss of a normal suppressor gene, and displayed glandular as well as squamous elements. Further characterization of these hybrids should permit isolation of specific suppressor genes, as well as promote recognition of elements that regulate the glandular phenotype.     

正常前列腺间质细胞对前列腺癌细胞糖代谢水平的影响

目的:探讨正常前列腺组织不同区带来源的前列腺间质细胞对前列腺癌细胞生长的影响及其作用机制。方法:以激素非依懒性前列腺癌细胞系DU145细胞为研究对象,取新鲜的正常前列腺外周带(PZ)和移行带(TZ)组织,提取间质细胞并体外培养。收集不同区带来源的间质细胞培养上清作为条件培养液培养DU145细胞,CCK8法测定肿瘤细胞的生长曲线,台盼蓝染色测定细胞数量及活力,细胞划痕实验测定细胞侵袭性,Western印迹法测定间质细胞对肿瘤细胞糖代谢关键酶的影响。结果:1PZ间质细胞的条件培养液能促进肿瘤细胞的生长,而TZ间质细胞的条件培养液抑制肿瘤细胞的生长;2PZ间质细胞的条件培养液明显增加肿瘤细胞糖代谢关键酶己糖激酶2(HK-2)、丙酮酸激酶2(PKM-2)、乳酸脱氢酶(LDHA)、丙酮酸脱氢酶(PDH)的表达,而TZ则抑制上述酶的表达。结论:前列腺不同来源的间质细胞对肿瘤细胞的生长影响不同,其机制可能与不同来源的间质细胞对糖酵解代谢的影响不同有关。     

Apoptosis of prostatic cells in male rats with diabetes mellitus

Apoptosis of prostatic cells in male rats with diabetes mellitus     

Genistein-induced neuroendocrine differentiation of prostate cancer cells

BACKGROUND: Neuroendocrine (NE) cells are present in normal prostate and their number appears to be increased in advanced prostate cancer (PCA). In this study, we studied the effect of the phytoestrogen, genistein, on NE differentiation of LNCaP cells in vitro. METHODS: Neuroendocrine marker expression of LNCaP cells exposed to genistein was measured by immunohistochemistry, Western blot, and real-time PCR methods. Western blot analysis was used to study cell cycle and signaling pathways induced by genistein treatment. RESULTS: Six days after continuous genistein treatment, the majority of genistein-surviving cancer cells underwent transdifferentiation into a NE-like phenotype overexpressing the NE markers chromogranin A, synaptophysin, serotonin, and beta-III tubulin. This NE differentiation process was associated with upregulation of the cell cycle modulators p21, p27, and p53, and activation of the MAPK and STAT3 pathways. CONCLUSION: Our data indicate that genistein evokes not only apoptosis but also NE transdifferentiation of PCA cells.     

有无间质细胞共培养条件下良性前列腺增生上皮细胞基因差异表达

目的　研究良性前列腺增生上皮细胞在有无间质细胞共培养条件下的基因差异表达。　方法　利用前列腺间质与上皮细胞共培养模型及DDRT PCR技术 ,对单独培养的前列腺增生上皮细胞和与间质细胞共培养的前列腺增生上皮细胞的mRNA进行差异表达分析 ,获得差异表达片段(ESTs) ;并对这些ESTs进行反向Northern印迹分析证实及克隆测序 ,将所测阳性克隆的cDNA序列与核苷酸数据库中已知序列进行同源性比较。　结果　得到ESTs 70个 ;经同源性分析 ,4 5个ESTs与已知基因有较高同源性 ,2 5个ESTs为新的cDNA片段。　结论　良性前列腺增生上皮细胞在有无间质细胞共培养条件下 ,存在差异表达基因 ,这些差异基因可能与前列腺间质细胞对前列腺增生上皮细胞的作用有关。     

Immunohistochemical characterization of neuroendocrine cells in prostate cancer

BACKGROUND: Neuroendocrine (NE) cells increase in high grade/stage prostate cancer (PC) and may contribute to androgen-independent cancer. Their immunohistochemical phenotype has not been studied in detail and conflicting results have been reported. METHODS: PC tissue was stained immunohistochemically for luminal secretory cell-associated cytokeratin, basal cell markers, ki-67, androgen receptor (AR), PSA, prostate acid phosphatase (PAP), and alpha-methylacyl coenzyme A racemase (AMACR). RESULTS: The NE cells are positive for AE1/AE3, Cam 5.2, and negative for basal cell markers. They are negative for AR, PSA, and Ki-67 but positive for PAP. The benign NE cells are negative for AMACR while the malignant NE cells are positive for AMACR. CONCLUSIONS: NE cells of PC constitute a unique subset of cancer cells, which have a unique immunohistochemical profile. They do not express AR, consistent with their resistance to hormonal therapy. They are post-mitotic cells but are malignant and part of the tumor.     

The multikinase inhibitor sorafenib induces caspase-dependent apoptosis in PC-3 prostate cancer cells

The present study investigated the effects of the multikinase inhibitor sorafenib on androgen-independent can- cer cells viability and intracellular signaling. Human androgen-independent PC-3 prostate cancer cells were treated with sorafenib. At concentration that suppresses extracellular signal-regulated kinase phosphorylation, sorafenib treatment reduced the mitochondrial transmembrane potential. Sorafenib also down-modulated the levels of mye- loid cell leukemia 1, survivin and cellular inhibitor of apoptosis protein 2. Sorafenib induced caspase-3 cleavage and the mitochondrial release of cytochrome c. However, no nuclear translocation of apoptosis inducing factor was detected after treatment and the pan-caspase inhibitor Z-VAD-FMK had an obvious protective effect against the drug. In conclusion, sorafenib induces apoptosis through a caspase-dependent mechanism with down-regulated antiapoptotic proteins in androgen-independent prostate cancer cells in vitro.     

Vitamin A regulates proliferation and differentiation of human prostatic epithelial cells

The response of cultured human prostatic epithelial cells to vitamin A was measured by clonal growth assay in serum-free medium. Retinoic acid at 3 nM or higher inhibited the proliferation of cell strains derived from normal, benign hyperplastic and malignant tissues, while lower levels (0.03 nM) were stimulatory. Reduced proliferation induced by retinoic acid was accompanied by a marked change in morphology, as intercellular adhesion decreased. In conjunction, the expression of keratins 8 and 18, associated with the differentiated luminal phenotype of prostatic epithelia, was increased. In post-confluent cultures, retinoic acid prevented the appearance of keratin 1, which accompanied the development of a squamous phenotype by cells maintained under these conditions. The findings of this study indicate a role for vitamin A as a modulator of the growth and differentiation of prostatic epithelial cells. © 1993 Wiley-Liss, Inc.