The mechanism of methylselenocysteine and docetaxel synergistic activity in prostate cancer cells

The study was designed to evaluate the combination treatment of methylselenocysteine (MSeC) and docetaxel and to delineate the underlying mechanism associated with observed in vitro synergy between MSeC and docetaxel in prostate cancer cells. Cells were treated with different concentrations and schedules (concurrent or sequential) of MSeC and docetaxel alone or in combination. Cell growth/death was assessed with sulforhodamine B assay, trypan blue assay, and time-lapse video. Loewe synergism/antagonism model was used to determine whether the combination effect was additive, synergistic, or antagonistic. Apoptosis and caspase-3 activity were evaluated with cell death ELISA assay and caspase activity assay, respectively. Synergy between MSeC and docetaxel was further assessed in the presence and absence of z-VAD-fmk, a pan-caspase inhibitor. Effect of MSeC and docetaxel alone or in combination on the cellular expression of the antiapoptotic protein survivin was measured with Western blot analyses. Pretreatment with MSeC was crucial to enhance docetaxel antitumor activity. The enhanced antitumor activity of the sequential combination treatment of MSeC and docetaxel (MSeC/docetaxel) was highly synergistic. Apoptosis increased after MSeC/docetaxel, compared with each drug alone or concurrent treatment. Pretreatment with z-VAD-fmk converted the synergy into antagonism, suggesting that the synergy is caspase-dependent apoptosis. The survivin level was down-regulated following MSeC/docetaxel treatment when compared with each drug alone. In conclusion, pretreatment with MSeC was essential to markedly sensitize cells to docetaxel. The synergy between MSeC and docetaxel in C2G prostate cancer cells is associated with increased level of caspase-dependent apoptosis and decreased level of survivin.     

前列腺癌细胞的原代和传代培养的研究

目的探讨前列腺癌细胞的培养方法,以便建立前列腺癌细胞系,为前列腺癌的基础研究提供实验模型.方法前列腺腺癌组织来源于我院两例患者的手术标本,分别采用组织块培养法、消化培养法和裸鼠肿瘤移植动物模型法对癌组织细胞进行体外分离培养.培养细胞按恶性肿瘤连续细胞系建系标准进行各项指标检测.结果组织块培养法有一例已稳定传为13代,消化培养法有一例已稳定传为23代,裸鼠肿瘤移植动物模型法未见癌肿生长.结论组织块培养法和消化培养法均为前列腺癌细胞培养的可行方法.     

前列腺癌细胞的原代和传代培养的研究

目的探讨前列腺癌细胞的培养方法,以便建立前列腺癌细胞系,为前列腺癌的基础研究提供实验模型。方法前列腺腺癌组织来源于我院两例患者的手术标本,分别采用组织块培养法、消化培养法和裸鼠肿瘤移植动物模型法对癌组织细胞进行体外分离培养。培养细胞按恶性肿瘤连续细胞系建系标准进行各项指标检测。结果组织块培养法有一例已稳定传为13代,消化培养法有一例已稳定传为23代,裸鼠肿瘤移植动物模型法未见癌肿生长。结论组织块培养法和消化培养法均为前列腺癌细胞培养的可行方法。     

Treatment of androgen-independent hormone refractory prostate cancer using docetaxel

Although prostate cancer patients with metastatic lesion initially respond to androgen ablation therapy, almost patients develop to hormone-refractory states. The optimal treatment for men with hormone refractory prostate cancer (HRPC) has not been established. Docetaxel is a semisynthetic taxane that inhibit tumor growth by induction of microtubule stabilization and promotion of bcl-2 inactivation, which induce apoptosis. Docetaxel as single agent has significant anti-tumor effect in HRPC patients. Docetaxel combined with estramustine or other antimicrotubular agents have shown further significant cytotoxicity in HRPC patients. In the United States, Food and Drug Administration (FDA) approved docetaxel, injection in combination with prednisone for the treatment of patients with advanced metastatic prostate cancer in 2004.     

Pulmonary toxicity during prostate cancer treatment with docetaxel and thalidomide

The standard therapies of surgery, radiotherapy, and hormonal manipulations often fail to control metastatic prostate cancer (PC). Docetaxel and thalidomide may have activity in refractory PC. We highlight the potential pulmonary toxicity when docetaxel is combined with thalidomide. We reviewed three examples of docetaxel and thalidomide pulmonary toxicity at the National Cancer Institute (NCI) and summarized the published literature regarding docetaxel and thalidomide pulmonary toxicity. Docetaxel and thalidomide pulmonary toxicity has the following four main presentations: (1). symptomatic effusions; (2). dyspnea on exertion without any objective pathologic evidence; (3). interstitial lung disease; and (4). pulmonary embolus. As chemotherapy becomes more common in the treatment of PC, clinicians must consider possible pulmonary toxicities. If pulmonary symptoms or signs develop, clinicians should consider holding chemotherapy pending a complete evaluation.     

Ethonafide-induced cytotoxicity is mediated by topoisomerase II inhibition in prostate cancer cells

Ethonafide is an anthracene-containing derivative of amonafide that belongs to the azonafide series of anticancer agents. The lack of cross-resistance in multidrug-resistant cancer cell lines and the absence of a quinone and hydroquinone moiety make ethonafide a potentially less cardiotoxic replacement for existing anthracene-containing anticancer agents. For this study, we investigated the anticancer activity and mechanism of ethonafide in human prostate cancer cell lines. Ethonafide was cytotoxic against three human prostate cancer cell lines at nanomolar concentrations. Ethonafide was found to be better tolerated and more effective at inhibiting tumor growth compared with mitoxantrone in a human xenograft tumor regression mouse model. Mechanistically, we found that ethonafide inhibited topoisomerase II activity by stabilizing the enzyme-DNA complex, involving both topoisomerase IIalpha and -beta. In addition, ethonafide induced a potent G(2) cell cycle arrest in the DU 145 human prostate cancer cell line. By creating stable cell lines with decreased expression of topoisomerase IIalpha or -beta, we found that a decrease in topoisomerase IIalpha protein expression renders the cell line resistant to ethonafide. The decrease in sensitivity to ethonafide was associated with a decrease in DNA damage and an increase in DNA repair as measured by the neutral comet assay. These data demonstrate that ethonafide is a topoisomerase II poison and that it is topoisomerase IIalpha-specific in the DU 145 human prostate cancer cell line.     

Effect of anticancer agents on Fas-mediated cytotoxicity against bladder cancer cells

Fas and Fas ligand play an important role in cytotoxic T lymphocyte-mediated cytotoxicity. Like Fas ligand, anti-Fas monoclonal antibody (mAb) induces apoptosis of cells expressing Fas and mimics tumor necrosis factor-α (TNF-α) in its cytotoxic activity, but not in regard to other TNF-α-mediated activities. Since combination treatment with TNF-α and some anticancer chemotherapeutic agents results in synergistic cytotoxicity against various cancer cells, anti-Fas mAb may also synergize with anticancer agents in exerting cytotoxicity. The present study examined this hypothesis using bladder cancer cells. Cytotoxicity was examined by a 1-day microculture tetrazolium dye assay. Treatment of T24 cells with anti-Fas mAb in combination with mitomycin C, methotrexate, or 5-fluorouracil did not overcome their resistance to these agents. However, combination treatment with anti-Fas mAb and adriamycin (ADR) resulted in a synergistic cytotoxic effect on T24 cells, three other bladder cancer lines, and fresh bladder cancer cells derived from four patients. Treatment with ADR enhanced the expression of Fas on T24 cells. The expression of P-glycoprotein was not affected by the antibody-mediated sensitization. This study showed that combination treatment of bladder cancer cells with anti-Fas mAb and ADR can overcome their resistance and that the upregulation of Fas expression by ADR may play a role in the enhanced cytotoxicity. Received: November 4, 1998 / Accepted: April 12, 1999     

Fas-mediated cytotoxicity by freshly isolated natural killer cells

The expression of Fas ligand on natural killer (NK) cells and Fas- mediated cytotoxicity by NK cells was investigated. Fas ligand mRNA was expressed in freshly isolated NK cells but not in T cells. Furthermore, the Fas ligand was detected on the cell surface of NK cells by staining with soluble Fas molecule. We analyzed the cytolytic activity of NK cells against thymocyte targets from normal and lpr mice, and found that the NK cells killed thymocytes from normal mice but not from lpr mice. On the other hand, splenic T cells did not show any cytotoxicity against either of the thymocyte targets. Similarly, NK cells exhibited cytotoxicity against transfectants expressing Fas antigen but not against parental cells or transfectants expressing a mutant Fas antigen with deleted cytoplasmic region. These results demonstrated that NK cells express Fas ligand and possess the capability of killing target cells expressing Fas antigen on their surface. This finding suggests that NK cells play an important role by eliminating Fas-expressing cells either constitutively or inducibly in peripheral lymphoid organs.     

Apoptosis induced by selenomethionine and methioninase is superoxide mediated and p53 dependent in human prostate cancer cells

Selenomethionine (SeMet) is the chemical form or major component of selenium used for cancer chemoprevention in several clinical trials. However, evidence from experimental studies indicates that SeMet has weaker anticancer effects than most other forms of selenium. Recent studies showed that the anticancer activity of SeMet can be enhanced by methioninase (METase), indicating that SeMet metabolites are responsible for its anticancer activity. In the present study, we showed that wild-type p53-expressing LNCaP human prostate cancer cells were more sensitive to cotreatment with SeMet and METase than p53-null PC3 human prostate cancer cells. SeMet and METase cotreatment significantly increased levels of superoxide and apoptosis in LNCaP cells. Cotreatment with SeMet and METase resulted in increased levels of phosphorylated p53 (Ser15), total p53, Bax, and p21(Waf1) proteins. LNCaP cells treated with SeMet and METase also showed p53 translocation to mitochondria, decreased mitochondrial membrane potential, cytochrome c release into the cytosol, and activation of caspase-9. The effects of SeMet and METase were suppressed by pretreatment with a synthetic superoxide dismutase mimic or by knockdown of p53 via RNA interference. Reexpression of wild-type p53 in PC3 cells resulted in increases in superoxide production, apoptosis, and caspase-9 activity and a decrease in mitochondrial membrane potential following cotreatment with SeMet and METase. Our study shows that apoptosis induced by SeMet plus METase is superoxide mediated and p53 dependent via mitochondrial pathway(s). These results suggest that superoxide and p53 may play a role in cancer chemoprevention by selenium.     

Combined targeting of epidermal growth factor receptor and hedgehog signaling by gefitinib and cyclopamine cooperatively improves the cytotoxic effects of docetaxel on metastatic prostate cancer cells

The epidermal growth factor receptor (EGFR) and hedgehog cascades provide a critical role in prostate cancer progression and contribute to the resistance to clinical therapies and disease relapse. Therefore, we evaluated, for the first time, the antiproliferative and cytotoxic effects induced by a combination of selective inhibitors of EGFR tyrosine kinase and smoothened hedgehog signaling element, gefitinib and cyclopamine, with a current chemotherapeutic drug used in the clinics, docetaxel, on some metastatic prostate cancer cell lines. Immunohistochemical analyses revealed that sonic hedgehog (SHH) expression was enhanced in 39% of primary prostatic adenocarcinomas (Gleason scores 4-10) compared with the corresponding normal tissues of the same prostate gland from 32 prostate cancer patients. The confocal microscopy and Western blot analyses have also indicated the high expression levels of SHH and EGFR in metastatic LNCaP, DU145, and PC3 cells. Moreover, the results revealed that the drugs, alone or in combination, at lower concentrations inhibited the growth of EGF plus SHH-stimulated and serum-stimulated androgen-responsive LNCaP-C33 and androgen-independent LNCaP-C81, DU145, and PC3 cells. Importantly, the combined docetaxel, gefitinib, and cyclopamine also caused a higher rate of apoptotic death of prostate cancer cells compared with individual agents. The cytotoxic effects induced by these drugs in PC3 cells seem to be mediated in part through the cellular ceramide production and activation of caspase cascades via a mitochondrial pathway and the release of cytochrome c into the cytosol. Additionally, the combined agents were more effective at suppressing the invasiveness of PC3 cells through Matrigel in vitro than the single drugs. These findings indicate that the combined use of inhibitors of EGF-EGFR and hedgehog signaling with docetaxel could represent a more promising strategy for treatment in patients with metastatic and androgen-independent prostate cancer.     

The radiosensitization effect of parthenolide in prostate cancer cells is mediated by nuclear factor-kappaB inhibition and enhanced by the presence of PTEN

Parthenolide has been shown to have anti-inflammatory and antitumor properties. However, whether and how parthenolide enhances tumor sensitivity to radiation therapy are unknown. In this study, we show that inhibition of the nuclear factor-kappaB (NF-kappaB) pathway is a common mechanism for the radiosensitization effect of parthenolide in prostate cancer cells LNCaP, DU 145, and PC3. Parthenolide inhibits radiation-induced NF-kappaB DNA-binding activity and the expression of its downstream target sod2, the gene coding for an important antiapoptotic and antioxidant enzyme (manganese superoxide dismutase) in the three prostate cancer cells. Different susceptibilities to parthenolide's effect are observed in two radioresistant cancer cells, DU 145 and PC3, with DU 145 cells showing higher sensitivity. This differential susceptibility to parthenolide is due, in part, to the fact that in addition to NF-kappaB inhibition, parthenolide activates the phosphatidylinositol-3-kinase/Akt prosurvival pathway in both cell lines. However, the activated Akt in DU 145 cells is kept at a relatively low level compared with that in PC3 cells due to the presence of functional PTEN. Transfection of wild-type PTEN into PTEN-null cells, PC3, confers the enhanced radiosensitization effect of parthenolide in PTEN-expressing cells. When PTEN expression is knocked down in DU 145 cells, the cells become more resistant to parthenolide's effect. Taken together, these results suggest that parthenolide inhibits the NF-kappaB pathway and activates the phosphatidylinositol-3-kinase/Akt pathway in prostate cancer cells. The radiosensitization effect of parthenolide is due, in part, to the inhibition of the NF-kappaB pathway. The presence of PTEN enhances the radiosensitization effect of parthenolide, in part, by suppressing the absolute amount of activated p-Akt.     

Acquired resistance to TRAIL-induced apoptosis in human ovarian cancer cells is conferred by increased turnover of mature caspase-3

Little is known on how cancer cells can acquire resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). In this study, we established TRAIL-resistant cells from the TRAIL-sensitive human ovarian carcinoma cell line OVCAR3 to evaluate the potential mechanisms of acquired resistance to TRAIL. The selected resistant cells were cross-resistant to Fas ligand but remained sensitive to drug-induced apoptosis. Expression of TRAIL receptors was not altered in TRAIL-resistant OVCAR3 cells. Cleavage of caspase-8 and caspase-3 occurred in both TRAIL-resistant and TRAIL-sensitive cells. However, mature caspase-3 fragments were not detected by immunoblot in TRAIL-resistant cells and caspase-3 activity was significantly inhibited in these cells. The addition of proteasome inhibitors significantly increased TRAIL-induced apoptosis in resistant cells and enhanced the accumulation of mature caspase-3 fragments. Pretreatment with cycloheximide showed that active caspase-3 fragments have a high turnover rate in OVCAR3 R350 cells. X-linked inhibitor of apoptosis down-regulation by RNA interference also increased the accumulation of cleaved caspase-3 intermediates and resensitized TRAIL-resistant cells. Our findings show that altered turnover of mature caspase-3 may lead to acquired TRAIL resistance in ovarian cancer cells. Proteasome and X-linked inhibitor of apoptosis inhibitors could have a role in clinical situations to potentiate the cytotoxic effects of TRAIL in resistant tumor cells.     

Human prostate cancer cells induce inflammatory cytokine secretion by peripheral blood mononuclear cells

A substantial number of studies provide evidence that inflammation may play a significant role in the pathogenesis of prostate cancer via increased activity of inflammatory cytokines, particularly IL-6. We have previously shown that peripheral blood mononuclear cells (PBMC) are capable of carrying out an in vitro “immunomodulatory dialog” with colon cancer cells expressed by an increased production of pro-inflammatory cytokines by PBMC. The aim of the current study was to examine the model of cell-to-cell interaction between PBMC and prostate cancer cells from two lines – androgen resistant (PC-3) and androgen-dependent (LNCaP). For that purpose, cancer cells from both lines were incubated with PBMC, and cytokine secretion by PBMC was evaluated. The results showed a cell-concentration dependent increase in secretion of the pro-inflammatory cytokine IL-6 by PBMC induced by cells from both lines, whereas generation of IL-1β and the anti-inflammatory cytokine IL-10 were found to be increased after incubation with PC-3 cells only. The secretion of IL-10 was slightly lower following incubation of PBMC with supernatants derived from PC-3 cells. The results of the study support the possibility that prostate cancer cell-induced cytokine production by PBMC, and particularly IL-6, are involved in prostate cancer development. The discrepancy between the effect of the two prostate cancer cell lines on cytokine secretion by PBMC may be due to their different androgen dependency.     

Risk factors for febrile neutropenia in patients receiving docetaxel chemotherapy for castration-resistant prostate cancer

Purpose

Docetaxel is a standard therapy for patients with castration-resistant prostate cancer (CRPC). However, docetaxel-associated adverse events (AEs) such as febrile neutropenia (FN) can impair quality of life and may become life-threatening. In this study, we clarified the AEs and risk factors associated with FN in clinical settings.

Methods

This study included 37 Japanese patients with CRPC who were treated with 70–75 mg/m² docetaxel and 10 mg prednisone every 3 or 4 weeks between 2008 and 2012. AEs, risk factors for FN, and the prognostic significance of several clinicopathological factors were analyzed.

Results

Hematological AEs of ≥grade 3 included neutrocytopenia in 36 patients (97.3 %), leukopenia in 24 patients (64.9 %), lymphopenia in 10 patients (27.0 %), and FN in 4 patients (10.8 %). In addition, severe non-hematological AEs included colonic perforation, interstitial pneumonia, and acute respiratory distress syndrome in 1 patient each. Severe lymphopenia was positively associated with the incidence of FN. Low serum albumin and low lymphocyte count were identified as possible pre-treatment risk factors, while severe lymphopenia was identified as a post-treatment risk factor.

Conclusions

Non-hematological AEs as well as substantial hematological AEs were recognized in the Japanese population treated with docetaxel chemotherapy against CRPC. Pre- and post-treatment lymphopenia and pre-treatment serum albumin should be considered in order to minimize the risk of FN when selecting patients with prostate cancer for docetaxel therapy, and when considering dose modifications, and the prophylactic use of granulocyte colony-stimulating factor.     

热休克胃癌细胞负载DC-CIK细胞杀伤癌细胞活性的研究

目的研究负载相关抗原的树突状细胞(DC)联合细胞因子诱导的杀伤(CIK)细胞对胃癌细胞的杀伤作用。方法取健康人外周血并分离出外周血单个核细胞(PBMC),经不同细胞因子分别诱导出DC和CIK细胞,热休克方法处理胃癌MKN-28细胞株并制备肿瘤抗原用于负载DC,与CIK细胞共培养,以流式细胞术检测DC、CIK细胞表型,MTS法检测CIK细胞对MKN-28细胞的杀伤作用。结果 CIK与DC共培养后,与单纯CIK细胞相比较,增殖活性明显提高,CD3+CD8+、CD3+CD56+双阳性细胞数增多并且具有更强的杀瘤活性,效靶比为20.0∶1时,负载MKN-28抗原的DC-CIK(Ag-DC-CIK)组对MKN-28的杀伤活性为(57.96±2.23)%,远大于未负载MKN-28抗原的DC-CIK组[(38.02±2.06)%]和单纯CIK组[(29.78±1.84)%],差异具有统计学意义(P<0.05)。结论以热休克凋亡肿瘤细胞抗原负载的DC能促进CIK细胞增殖分化,并提高其对胃癌细胞的杀伤活性。