PC-3 Prostate Adenocarcinoma Cells Research Articles

Suppression of VEGF-mediated autocrine and paracrine interactions between prostate cancer cells and vascular endothelial cells by soy isoflavones

Angiogenesis is an essential process involved in the development and progression of prostate cancer. Vascular endothelial growth factor (VEGF) is hypothesized to be a critical regulator of angiogenesis during prostate carcinogenesis. We have reported that dietary soy products inhibit prostate tumor progression in animal models, in association with a reduction in tumor microvessel density. The goal of the present study is to investigate potential antiangiogenic mechanisms of genistein, the major soy isoflavone, using in vitro systems. Genistein (5–50 μM) significantly inhibited the growth of human umbilical vein endothelial cells (HUVECs) in control media when stimulated by supplemental VEGF or when cultured in hypoxia-exposed PC-3 prostate adenocarcinoma cell conditioned media. These in vitro studies suggest detectable inhibitory effects by 5–10 μM genistein ( P<.05) with an IC 50 of approximately 20 μM or less. Genistein (10–50 μM) caused significant inhibition of basal VEGF expression and hypoxia-stimulated VEGF expression in both human prostate cancer PC-3 cells and HUVECs based on semiquantitative reverse transcription–polymerase chain reaction ( P<.05). In parallel, VEGF secretion by PC-3 cells quantitated by enzyme-linked immunosorbent assay was significantly ( P<.05) reduced by genistein (10–50 μM). Furthermore, genistein (10–50 μM) significantly ( P<.05) reduced PC-3 nuclear accumulation of hypoxia-inducible factor-1α, the principle transcription factor that regulates VEGF expression in response to hypoxia. Expression of the VEGF receptor fms-like tyrosine kinase-1, but not kinase insert domain-containing kinase, in HUVECs was also reduced ( P<.05) by genistein (10–50 μM). These observations support the hypothesis that genistein may inhibit prostate tumor angiogenesis through the suppression of VEGF-mediated autocrine and paracrine signaling pathways between tumor cells and vascular endothelial cells.

Hematopoietic cells regulate the angiogenic switch during tumorigenesis

AbstractHematopoietic cells (HCs) promote blood vessel formation by producing various proangiogenic cytokines and chemokines and matrix metalloproteinases. We injected mouse colon26 colon cancer cells or human PC3 prostate adenocarcinoma cells into mice and studied the localization of HCs during tumor development. HCs were distributed in the inner tumor mass in all of the tumor tissues examined; however, the localization of HCs in the tumor tissue differed depending on the tumor cell type. In the case of colon26 tumors, as the tumor grew, many mature HCs migrated into the tumor mass before fine capillary formation was observed. On the other hand, although very few HCs migrated into PC3 tumor tissue, c-Kit+ hematopoietic stem/progenitor cells accumulated around the edge of the tumor. Bone marrow suppression induced by injection of anti–c-Kit neutralizing antibody suppressed tumor angiogenesis by different mechanisms according to the tumor cell type: bone marrow suppression inhibited the initiation of sprouting angiogenesis in colon26 tumors, while it suppressed an increase in the caliber of newly developed blood vessels at the tumor edge in PC3 tumors. Our findings suggest that HCs are involved in tumor angiogenesis and regulate the angiogenic switch during tumorigenesis.

Anti-CD3 × Anti-HER2 Bispecific Antibody Effectively Redirects Armed T Cells to Inhibit Tumor Development and Growth in Hormone-Refractory Prostate Cancer–Bearing Severe Combined Immunodeficient Beige Mice

The bispecific antibody (BiAb) anti-CD3 × anti-Her2/neu (Her2Bi), combines Her2/neu targeting with nonmajor histocompatibility complex–restricted cytotoxicity mediated by activated T cells (ATCs). To evaluate this adaptive immunotherapeutic strategy for augmenting antitumor immune response toward hormone-refractory prostate cancer (HRPC), normal donor or patient T cells were activated with anti- CD3, expanded ex vivo in interleukin-2, and then armed with Her2Bi (5-500 ng per million ATCs). In vitro, arming ATCs with Her2Bi increased the percent specific cytotoxicity toward PC-3 prostate adenocarcinoma cells 2-3 fold and increased the secretion of Th₁ cytokines granulocyte-macrophage colony-stimulating factor, tumor necrosis factor–α, and interferon-γ when compared with unarmed ATCs or ATCs armed with an irrelevant BiAb. Her2Bi-armed ATCs administered with PC-3 (Winn Assay) or injected intratumorally prevented development or induced remissions, respectively, of PC-3 tumors in severe combined immunodeficient beige mice. Intravenously administered Her2Bi-armed ATCs localized to PC-3 xenografts mediated cytotoxicity toward tumor cells and produced significant tumor growth delay of PC-3 tumors, but not Her2/neu–negative LS174T colon adenocarcinoma xenografts. By flow cytometry analyses, Her2Biarmed ATCs had a proliferative advantage over unarmed ATCs and persisted in the circulation and tumor tissues longer than unarmed ATCs. These findings suggest that Her2Bi-armed ATC therapy may be an effective, nontoxic, tumor-specific treatment for Her2-positive HRPC.

Regulation of Interleukin-8 Expression by Cellular pH in Human Pancreatic Adenocarcinoma Cells

The role of cellular pH in the expression and regulation of interleukin-8 (IL-8) in human tumor cell lines was determined. Transient exposure to pH ranging from 7.4 to 6.7 induced pH-dependent expression of IL-8 at both the mRNA and protein levels in three different human tumor cell lines, including COLO357 pancreatic adenocarcinoma cells, SW620 colon adenocarcinoma cells, and PC3 prostate adenocarcinoma cells. Investigation of the mechanisms of IL-8 induction in response to acidosis was carried out using the COLO357 human pancreatic cancer cell line. The increased steady-state level of mRNA correlated with an increased transcription rate and stability of IL-8 transcripts. Further experiments indicated that mild acidosis activated the transcription factors NF-kappaB and AP-1 and that the cooperation of these two factors appeared to be essential to the transactivation of the IL-8 gene. Our data demonstrated that low tumor pH contributes to the enhanced expression of IL-8 and plays an important role in tumor progression.