Effect of radiation combined with hyperthermia on human prostatic carcinoma cell lines in culture

The effect of radiation combined with heat on three human prostatic carcinoma cell lines growing in vitro was investigated. Cells were exposed to different radiation doses followed by heat treatment at 43 degrees C for one hour. Heat treatment, given ten minutes after radiation, significantly enhanced the radiation response of all the cell lines studied. The combined effect of radiation and heat produced greater cytotoxicity than predicted from the additive effects of the two individual treatment modalities alone. These results indicate that a combined treatment regimen of radiation plus hyperthermia (43 degrees, 1 hr) might be an important tool in maintaining a better local control of prostatic cancer.     

In vitro study of the effect of hyperthermia on normal bladder cell line and on five different transitional cell carcinoma cell lines.

Intraluminal hyperthermia is potentially useful in the management of superficial bladder cancer. The potential inhibitory effect of hyperthermia on various human bladder cancer cell lines, normal human bladder cells and the murine MBT-2 bladder cancer cell line has been studied in vitro. These cell lines were exposed for one hour to 43 +/- 0.5C and compared to controls. Cell survival was assessed comparing the cell growth curve and colony formation. The human transitional cell carcinoma (TCC) cell lines vary in their sensitivity to heat. MGH-U1 was the most heat sensitive cell line. The human A-1698, CUB-2, UM-UC-3 and the murine MBT-2 lines were heat insensitive. We conclude that the cytocidal effect of hyperthermia in bladder transitional cell carcinoma is variable. Further experiments using the combination of hyperthermia and intravesical anticancer agents are in progress.     

Combined cell killing effects of anticancer drugs and hyperthermia in vitro

Using an in vitro colony forming assay system, cytotoxic effects of anticancer drugs, adriamycin (ADM) and peplomycin (PEP), and the combined effect of hyperthermia and anticancer drugs on cultivated KK-47 cells were investigated. From the response curves obtained at 42 and 43 degrees C hyperthermia, 20% growth inhibition time (IT20) at 42 and 43 degrees C hyperthermia and 50% growth inhibition time (IT50) at 43 degrees C were calculated. The IT20 and IT50 hyperthermia were combined with a 2-hour treatment of each of the anticancer drugs. When the hyperthermia was combined with various concentrations of ADM ranging from 0.005 to 0.1 microgram/ml, enhanced cell killing effects were obtained at the concentrations of less than 0.02 microgram/ml of ADM, whereas, there was no increase in cell killing effect at the concentrations of more than 0.05 microgram/ml of ADM. The combination of hyperthermia with PEP considerably enhanced the cell killing effects with an increase of PEP concentration.     

The effect of hyperthermia on mitomycin-C induced cytotoxicity in four human bladder cancer cell lines

INTRODUCTION: Hyperthermia and mitomycin-C (MMC) have given very encouraging results in several clinical studies for the treatment of superficial transitional cell carcinoma of the bladder. However, a synergistic effect of hyperthermia and MMC on the decrease of cell proliferation has never been demonstrated accurately in vitro. We investigated the effect of MMC versus MMC combined with hyperthermia on the cytotoxicity in four human bladder cancer cell lines. MATERIAL AND METHODS: The RT112, RT4, 253J and T24 human bladder cancer cell lines were seeded in 96-well microtiter plates at 2.0 x 10(4) cells per well and were left to attach for 24 hours. The cells were then treated for 60 minutes with MMC concentrations ranging from 0 to 400 microg/ml at a temperature of 37 degrees C or 43 degrees C. After treatment cells were rinsed three times with culture medium and left for 24 hours in the incubator. Dimethyl thiazolyl tetrazolium (MTT) solution was added and after 4 hours of incubation the MTT containing media was aspired from all wells and 100 microl of dimethyl sulfoxide was added to each well. A spectrum analyses was performed at 595 nm light wavelength. RESULTS: A decrease of cell proliferation after treatment with increasing concentrations MMC was demonstrated. Hyperthermia has a synergistic effect on the decrease of cell proliferation by different concentrations MMC. In the cells treated without MMC no significant difference in the extent of cell killing at 37 degrees C and 43 degrees C was observed. Furthermore, no difference was observed between cells with a p53 protein mutation (RT112 and T24) or without a p53 protein mutation (253J and RT4). Conclusion: A clear synergistic effect of MMC and hyperthermia has been demonstrated in four human bladder cancer cell lines.     

Estramustine phosphate enhances the effects of hyperthermia and induces the small heat shock protein HSP27 in the human prostate carcinoma cell line PC-3

The antimicrotubule drug estramustine phosphate (EMP) has been shown to sensitize prostate carcinoma cells to radiation via synchronization at the G2/M phase of the cell cycle. This synchronization may also render cells more sensitive to hyperthermia, providing a rationale for multimodal treatment approaches. We have investigated the effects of EMP and hyperthermia, as well as the regulation of heat shock proteins (HSP) in the PC-3 prostatic carcinoma cell line. Cells were incubated with four doses of EMP for 48 h followed by a 1-h hyperthermia treatment ranging from 41 degrees C to 44 degrees C. Cell cycle distribution at the end of the EMP incubation was investigated by flow cytometry. Cytotoxicity was assessed by colony formation assays. HSP accumulation was investigated by Western immunoblotting. Doses of 1, 5, 10 and 15 microM EMP synchronized 27, 28, 46, and 68% of PC-3 cells at G2/M. With 5, 10 and 15 microM, a sensitizing effect of EMP was assessed at hyperthermic temperatures of 42, 43 and 44 degrees C. EMP did not alter the expression of HSP72, but substantially induced the synthesis of HSP27 in PC-3 cells. Our data show that EMP sensitizes PC-3 cells to hyperthermia induced cytotoxicity. This observation supports the rationale for multimodal treatment approaches in locally advanced prostate cancer.     

Inhibitory effects of the nucleoside analogue gemcitabine on prostatic carcinoma cells

Gemcitabine (2≺,2≺difluoro-2≺deoxycytidine, dFdC) is a synthetic antimetabolite of the cellular pyrimidine nucleotide metabolism. In a first series of in vitro experiments, the drug showed a strong effect on the proliferation and colony formation of the human androgen-sensitive tumor cell line LNCaP and the androgen-insensitive cell lines PC-3 and DU-145. Maximal inhibition occurred at a dFdC concentration as low as 30 nM. In contrast to the cell lines which were derived from metastatic lesions of prostate cancer patients, no inhibitory effects were found in normal primary prostatic epithelial cells at concentrations up to 100 nM. The effect of gemcitabine was reversed by co-administration of 10–100 μM of its natural analogue deoxycytidine. In view of a future clinical application of this anti-tumor drug in advanced prostatic carcinoma, we have compared the effect of gemcitabine on prostatic tumor cells with that on bone marrow granulopoietic-macrophagic progenitor cells, because neutropenia is a common side effect of gemcitabine treatment. The time course of action on the two kinds of cells was markedly different. Colony formation of tumor cells was inhibited by two thirds at a gemcitabine concentration of about 3.5 nM. The same effect on granulopoietic-macrophagic progenitor cells required a concentration of 9 nM. Co-administration of deoxycytidine to gemcitabine-treated tumor cell cultures completely antagonized the effect of gemcitabine whereas addition of deoxycytidine after 48 hr of gemcitabine treatment could not prevent gemcitabine action on the tumor cells. In contrast, more than half of the granulopoietic-macrophagic progenitor cells could still be rescued by deoxycytidine administration after 48 hr. These findings and the marked difference in the susceptibility of neoplastic and normal prostatic cells suggest that gemcitabine is a promising substance which should be further evaluated as to its efficacy in the treatment of advanced prostatic carcinoma. © 1996 Wiley-Liss, Inc.     

The influence of hyperthermia in vitro on the functions of peritoneal macrophages in mice

Total-body hyperthermia (TBHT) as a treatment for cancer may lead to a reduction in the host's immunocompetence as a result of the direct effects of heat on the immune system. Thus, we studied the influences of hyperthermia in vitro on the function of peritoneal macrophages from mice. Peritoneal macrophages from C3H/HeN mice were heated in vitro for 3 hr at 37, 39, 40, 41 or 42 degrees C. After exposure to heat, the phagocytic ability of the macrophages, as well as results of the nitroblue tetrazolium (NBT) reduction test and the cytotoxicity test were examined. The changes in all these parameters showed almost the same pattern: a tendency for macrophage functions to be potentiated up to 40 degrees C, and a tendency towards inhibited functioning at temperatures above 41 degrees C. Although augmented functions of macrophages were observed after exposure to mild hyperthermia (less than 40 degrees C), the possibility of TBHT (42 degrees C)-induced inhibition of macrophage function must be further investigated in clinical trials of TBHT therapy for cancer.     

In vitro response of human glioblastoma and canine glioma cells to hyperthermia, radiation, and chemotherapy

Little is known about the sensitivity of human glioblastoma cells to hyperthermia alone and in combination with other therapies. We carried out in vitro cell survival studies on the human glioblastoma cell line U-87MG and our model canine glioma canine brain tumor (CBT) cells after multimodality treatment. Ionizing radiation was administered to flasks of cells in logarithmic growth at 500 rads (5 Gy) with consecutive treatment by hyperthermia, 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU), or cisplatin. Cells were treated with single doses of BCNU at 5 microM with sequentially added radiation or hyperthermia and at 1 to 2 micrograms/ml of cisplatin with hyperthermia. Hyperthermia was administered in a precision controlled water bath at 44 degrees C for 30 minutes in combination with chemotherapy or radiation. In general, the sensitivity of U-87MG and CBT cells was similar for all test regimens. For example, colony formation efficiency decreased by 64% in CBT cells and by 64.4% in U-87MG cells after hyperthermia alone at 44 degrees C for 60 minutes. All combinations of BCNU, hyperthermia, and radiation administered in vitro produced enhanced cell killing, but the effects of multiple modalities were generally additive in both cell lines.(ABSTRACT TRUNCATED AT 250 WORDS)     

Combination effects of CDDP and hyperthermia in mouse bladder tumor (MBT-2)

The combination effects of CDDP and hyperthermia in mouse bladder tumor (MBT-2) were investigated both in vivo and in vitro. MBT-2 was transplanted into the hind leg of a C3H/He mouse. Then the leg was dipped in a hot water bath immediately after the intraperitoneal administration of CDDP. The antitumor effects were evaluated from tumor volume. The CDDP plus hyperthermia (43 degrees C) group showed remarkable tumor growth retardation. The in vitro colony forming assay showed that MBT-2 cultured cells treated with CDDP at 42 degrees C exhibited great colony forming inhibition in comparison with the CDDP alone cells. The effects of CDDP plus hyperthermia on the cell cycle progression of MBT-2 cultured cells were studied by using flow cytometry. The results showed that the cells treated with CDDP at 42 degrees C exhibited an accumulation of cells in the C2 phase for many hours as compared with the CDDP alone cells, indicating thermal enhancement of DNA damage in MBT-2 cultured cells treated with CDDP.     

Thermal sensitization through ROS modulation: a strategy to improve the efficacy of hyperthermic intraperitoneal chemotherapy

BACKGROUND: The purpose of this study was to investigate whether modulation of cellular reactive oxygen species (ROS) provides a synergistic effect with hyperthermia to induce tumor cell death in a colon cancer cell line. MATERIALS AND METHODS: HT-29 colon cancer cells were exposed to heat (43 degrees C) in the presence of the ROS-generating drug, 2-2'-azobis-(2-amidinopropane) dihydrochloride (AAPH) for 1 h. Viable cell mass and apoptosis was measured by MTT and annexin V staining, respectively. Oxidative stress was evaluated by DCFH fluorescence. Protein levels were determined by Western blot analysis. RESULTS: A synergistic effect on cell viability with AAPH was noted under hyperthermic conditions as compared with hyperthermia alone (P < .05). The number of nonviable cells after hyperthermia and AAPH exposure was also significantly increased compared with AAPH at 37 degrees C (42% vs 20%, P < .05). ROS levels were increased modestly with AAPH at 37 degrees C, whereas they increased significantly in a dose-dependent manner with AAPH at 43 degrees C. Transient increases of phosphorylated-p38 and ERK and decreases in phosphorylated-AKT were observed in the cells exposed to AAPH at 43 degrees C. Pretreatment of inhibitors of p38 yielded additional decreases in cell mass when used in combination with AAPH and hyperthermia (P < .05). Increased expression of HSP 27 observed at 43 degrees C was abrogated with AAPH exposure. CONCLUSIONS: Oxidative stress increased the cytotoxic effects of hyperthermia in colon cancer cells. Thermal sensitization through modulation of cellular ROS may represent a novel approach to increase the efficacy of hyperthermia as an anticancer modality.     

In vitro effects of epidermal growth factor (EGF) on growth of urological malignant tumor cells

It is well known that Epidermal Growth Factor (EGF) is a cell-regulating factor for variety of tissues in vitro including normal and malignant cells. Furthermore, Takano et al reported that a decreased expression of EGF receptor in clones of human cancer KB cell line might be one of the pleiotropic properties of multidrug-resistant cells. However, both the influence of EGF on human urological cancer cell lines and the relation between EGF receptors and sensitivities of antitumor drugs on these cell lines have not been fully described. We have studied the effects of EGF on growth of 4 transitional carcinoma cell lines of bladder (TCCaB), 1 squamous cell carcinoma cell line of bladder (SCCaB), 5 renal cell carcinoma cell lines (RCC) and 3 prostatic carcinoma cell lines (CaP), as well as the relationship between the number of EGF receptors and drug sensitivities of these cell lines in vitro against methotrexate, vinblastine, adriamycin, cisplatin and etoposide (VP16). The present results determined by the in vitro colony forming efficiency method showed that exogenous addition of EGF to cell cultures at 0.1 ng/ml stimulated the growth of SCCaB by 169.0%, and at 1 ng/ml inhibited that of RCC by 2.9%-79.0%, relative to control. The more EGF receptors by 125I-EGF binding assay, the higher inhibition of VP16 on the growth of these cell lines. These results suggested that EGF stimulated the growth of SCCaB and inhibited the growth of RCC in vitro, and we found that these phenomena were correlated with neither the number of EGF receptors nor affinities of that receptors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Oncolytic viral gene therapy for prostate cancer using two attenuated,replication-competent,genetically engineered herpes simplex viruses

BACKGROUND: Attenuated, replication-competent herpes simplex virus mutants offer an exciting new modality in cancer therapy through their ability to selectively replicate within and kill malignant cells with minimal harm to normal tissues. METHODS: This study investigates the efficacy of two such viruses, G207 and NV1020, in human prostatic carcinoma. In vitro studies were performed on four human prostatic carcinoma cell lines, and in vivo single/multiple dose studies were undertaken on mice by using two human cell types. Tumor volume, histopathology at necropsy, and serum prostate specific antigen (PSA) were used as measures of antiproliferative effect in the in vivo experiments. RESULTS: Both viruses were effective in producing cytolytic effects in vitro at various multiplicities of infection in all cell lines tested. Both viruses demonstrated antitumor effects in vivo with a statistically significant decrease in serum PSA and inhibition of growth of both PC-3 and C4-2 subcutaneous xenografts. Tumor-free animals at necropsy were observed in the treated groups but not in control animals. CONCLUSION: These results display impressive activity against human prostate cancer and offer promise for the use of this modality in the future.     

Adriamycin combined with hyperthermia and dipyridamole is cytotoxic both in vitro and in vivo.

The cytotoxicity of adriamycin (ADM) combined with hyperthermia (Hyp) and/or dipyridamole (DP) was investigated using B16 melanoma cells in vitro and in vivo. When ADM was combined with Hyp at 43 degrees C or DP in a dose of 5 microM or with both, drug cytotoxicity enhanced the inhibition of colony formation and cell growth, and the effect was maximal when Hyp and DP were combined. Incubation with DP alone for 24 h, following ADM exposure, enhanced the toxicity even further (p less than 0.01). Measurement of intracellular levels of ADM in the B16 melanoma cells showed that Hyp and DP increased accumulation of ADM, and that DP, but not Hyp, significantly suppressed the ADM excretion (p less than 0.05). Growth of B16 melanoma implanted into subcutaneous tissue of the foot of C57BL mice was inhibited to a greater extent by the combination treatment of ADM and DP, ADM and Hyp, and also that of ADM, Hyp and DP, compared to the findings in cases of ADM or Hyp alone. As this trimodality treatment is effective both in vitro and in vivo, further study on possible clinical advantage is warranted.     

Effect of hyperthermia on the cytotoxicity of 4 chemotherapeutic agents currently used for the treatment of transitional cell carcinoma of the bladder: an in vitro study

PURPOSE: Hyperthermia combined with chemotherapy is not a novel cancer treatment. However, the working mechanism of this combination therapy is not fully understood. In the current in vitro study we investigated the differences in cytotoxicity of 4 chemotherapeutic agents at 37C or 43C. MATERIALS AND METHODS: The human transitional cell carcinoma cell lines used were RT4, RT112, 253J and T24. Cells were seeded in 96-well microtiter plates. After 24 hours cells were treated for 60 minutes with increasing concentrations of mitomycin C, epirubicin, gemcitabine and EO9 at a temperature of 37C or 43C. After treatment cells were rinsed 3 times and left for 24 hours in the incubator at 37C. The influence of chemotherapy and temperature on cell survival was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) assay. RESULTS: Decreased cell proliferation with increasing concentrations of chemotherapeutic agents was demonstrated. EO9 proved to be the most potent agent at each temperature. Hyperthermia alone did not demonstrate decreased cell proliferation. However, a synergistic effect on decreased cell proliferation was demonstrated in all cell lines and chemotherapeutic agents used, although each had a maximum at a different chemotherapy concentration and to a different extent. Synergism was most obvious in cell lines treated with low dose epirubicin. CONCLUSIONS: Synergism with hyperthermia and chemotherapy was clearly demonstrated for epirubicin, EO9, mitomycin C and to a lesser extent gemcitabine. Hyperthermia alone did not cause decreased cell proliferation. Synergism was most prominent with low drug doses and the most potent drug used in this in vitro study was EO9.     

温热疗法增强前药氟胞嘧啶对转基因结肠癌细胞株的杀伤作用

目的 探讨温热疗法能否增强前药5-氟胞嘧啶（5-fluorocytosine，5-FC）对转染组织特异性胞嘧啶脱氨基酶（cytosine deaminase，CD）基因的结肠癌细胞SW480的靶向性杀伤作用及其机制。方法 将转染G1CEACDNa之结肠癌SW480细胞接种到96孔细胞培养板中，同时加入含各种浓度梯度的前药5-FC。实验组以水浴加温法在43℃下热处理30min，对照组不加热。第8d去除培养液，以MTT法测定活细胞比率，分析前药5-FC联合温热疗法对转CD基因结肠癌SW480细胞的杀伤作用，并以流式细胞仪分析热化疗对肿瘤细胞周期的影响，透射电镜观察热化疗前后肿瘤细胞形态学改变。结果 实验组细胞的杀伤率明显高于对照组（P〈0．05，t=2．403，n=9）；流式细胞仪检测显示实验组S期细胞比例明显增高（P〈0．001，t=7．158，n=6）；透射电镜观察下显示实验组细胞膜微绒毛消失，边缘变平直，细胞核皱缩，染色质聚集在核模下。结论 温热疗法能明显提高转CD基因结肠癌SW480细胞对前药5-FC的敏感性；两者联用能使转CD基因结肠癌SW480细胞产生S期阻滞，从而促进细胞凋亡。     

Experimental studies on thermotolerance in hyperthermia treatment of cancer

Thermotolerance was investigated in hyperthermia using FM3A cells in vitro and in vivo. FM3A cells were heated at 42.0 degrees C, 43.0 degrees C and 44.0 degrees C and the survival rate of the cells was decreased in this order. In in vitro experiments, thermotolerance induced by heating at 43.0 degrees C for 30 min reached at maximum, when the heating interval was 12 hr and thermotolerance induced by heating at 44.0 degrees C for 30 min reached at maximum, when the heating interval was 12 to 24 hr. In in vivo experiments, thermotolerance induced by heating at 42.0 degrees C, 43.0 degrees C and 44.0 degrees C continued for 48 hr after initial heating and disappeared after 96 hr. In the repeated hyperthermia experiments, 7 times with 24 hr interval heating or 4 times with 48 hr interval heating did not show the significant inhibition of tumor growth as compared with the control group at 42.0 degrees C, 43.0 degrees C and 44.0 degrees C. However, twice with 96 hr interval heating indicated the significant inhibition of tumor growth at 42.0 degrees C, 43.0 degrees C and 44.0 degrees C. From these results it is suggested that hyperthermia treatment should be repeated after the disappearance of thermotolerance.     

Hedgehog信号通路在胃癌细胞中活化并通过GLI1促进MKN28细胞增殖

目的研究Hedgehog：（HH）信号通路在胃癌细胞中的活化形式及其转录因子GLI1对胃癌细胞增殖和体外成瘤能力的影响。方法通过反转录PCR分析HH通路相关组成分子在7株细胞系中的表达情况．化学合成针对HH信号通路转录因子GLI1的siRNA并转染胃癌MKN28细胞。通过CCK8法和体外克隆形成实验．观察GLII siRNA转染胃癌MKN28细胞后的细胞增殖能力和克隆形成能力的变化。结果在不同胃癌细胞株中．HH信号通路各相关基因的表达情况存在差异,SHH在6株胃癌细胞系中均表达上调．PTCH在KATOⅢ细胞系、SUFU在MKN28和KATOⅢ表达下调。转染GLI1 siRNA后,MKN28细胞中GLI1 mRNA表达受到明显抑制;经GLI1 siRNA作用的MKN28细胞生长明显缓于阴性对照和未处理组（P=0．014）,克隆形成数目及体外克隆形成能力降低（P〈0．001）。结论HH信号通路在胃癌细胞系中被普遍激活,HH信号通路活化后可通过转录因子GLI1促进MKN28细胞增殖．     

SENSITIVITY OF HUMAN PROSTATIC CARCINOMA CELL LINES TO LOW DOSE RATE RADIATION EXPOSURE

Purpose

Low dose rate radioemitters, such as¹²⁵ I,¹⁰³ Pd, and sup 89 Sr, have been used both for local and systemic treatment of prostate cancer. Most normal cells exposed to ionizing radiation characteristically activate cell cycle checkpoints, resulting in cell cycle arrest at the G₁/S and G₂/M transition points. Cancer cells are typically quite sensitive to radiation killing late in the G₂ phase of the replicative cell cycle. Furthermore, most cancer cells accumulating at the G₂/M transition point as a result of low dose rate radiation exposure appear to become sensitive to further low dose rate irradiation. For this reason, protracted exposure of cancer cells to low dose rate radiation has been proposed to result in increased cancer cell killing as compared with brief exposures of cancer cells to high dose rate radiation. Since many human prostatic carcinomas contain somatic genome alterations targeting genes which affect the cell cycle and radiation-associated cell cycle checkpoints, we evaluated the effects of low dose rate radiation exposure on the cell cycle and on clonogenic survival for various human prostatic carcinoma cell lines.

Materials and Methods

Human prostatic carcinoma cells from the LNCaP, DU 145, PC-3, PPC-1, and TSU-Pr1 cell lines were exposed to low dose rate (0.25 Gy/hour) or high dose rate (60 Gy/hour) radiation in vitro and then assessed for radiation cytotoxicity by clonogenic survival assay. Cell cycle perturbations following protracted exposure to low dose rate radiation were evaluated using flow cytometry.

Results

For LNCaP cells, low dose rate radiation exposure resulted in an accumulation of cells at both the G₁/S and the G₂/M cell cycle transition points. For DU 145, PC-3, PPC-1, and TSU-Pr1 cells, treatment with low dose rate radiation triggered G₂/M cell cycle arrest, but not G₁/S arrest. Unexpectedly, the cell cycle redistribution pattern phenotypes observed, G₁/S and G₂/M cell cycle arrest versus G₂/M arrest alone, appeared to have little effect on low dose rate radiation survival. Furthermore, while PC-3, PPC-1, and TSU-Pr1 cells exhibited increased cytotoxic sensitivity to low dose rate versus fractionated high dose rate radiation treatment, DU 145 and LNCaP cells did not.

Conclusions

Radiation-associated pertubations in replicative cell cycle progression were not dominant determinants of low dose rate radiation killing efficacy in human prostate cancer cell lines in vitro.     

Enhanced radioinduced cytotoxicity of cultured human bladder cancer cells using 43°C hyperthermia or anticancer drugs

Summary Using a colony-forming technique and 2 human bladder cancer cell lines, T24 and KK-47, the enhanced radioinduced cytotoxicity in combination with 43°C hyperthermia (HPT) or 4 anticancer drugs; bleomycin (BLM), cis-dichlorodiammineplatinum (II) (CDDP), mitomycin C (MMC), carbazilquinone (CQ), has been studied. In the series of both cell lines, the combination of 43 °C hyperthermia and irradiation resulted in exceedingly enhanced cytotoxicity. This was characterized by a marked decline of the slope of the radiation dose-survival curve as compared with slope in the combination of each of the anticancer drugs and irradiation. Among the 4 anticancer drugs, BLM was thought to be the most promising agent as a potentiator of the radiotherapy, on the basis of a remarkable decrease in the shoulder portion of the radiation dose-survival curve. The other 3 anticancer drugs showed a certain degree of potentiation of radiosensitivity.     

Inhibition of prostate cancer cell growth by activated eosinophils

BACKGROUND: Host Immune response to prostate cancer primarily involves the CTL and NK effector cells. Recent immunotherapeutic strategies incorporating cytokine genes into the tumor cell and/or dendritic cells have had encouraging results. In this study, we describe the inhibitory activity of a third potential effector cell, the eosinophil, against DU 145 and PC-3 prostate tumor cells growth in vitro. METHODS: Subconfluent monolayer cultures of DU 145 and PC-3 cells were incubated with peripheral blood eosinophils from allergic or asthmatic individuals and also with eosinophil cultured supernatants. Newly established eosinophil cell lines were also studied. After harvesting, the plates were washed and stained with Hematoxylin/eosin (H/E) then photographed. The combination of monolayer cell growth inhibition and colony formation inhibition assays were used to evaluate eosinophil inhibitory activity. In the colony formation inhibition assay one hundred cells per well in 6-well plates were incubated overnight, after which peripheral blood eosinophils, conditioned media and cytokines, IL-4 and TNF-alpha were added. The plates were harvested after 10 days incubation period. Colonies were stained and counted. RESULTS: Hypo- and hyperdense peripheral blood eosinophils from allergic and asthmatic individuals as well as eosinophil cell lines established from these subpopulations inhibited both DU 145 and PC-3 cell growth at 58-78% and 10-38%, respectively. IL-5 up-regulated eosinophil cell line activity by 21-24%. The conditioned media which contained the released mediators of activated eosinophils were potent in their actions on both DU 145 and PC-3, inhibiting colony formation by as much as 90-100%. CONCLUSION: These results clearly demonstrate the inhibitory potential of activated eosinophils and their released "soup" of mediators and therefore support the hypothesis that eosinophils may participate in host response to prostate cancer together with CTLs and NK cells. Furthermore, this study offers insights into possible strategies for enhancing eosinophilic activity in prostate cancer.