Thermal enhancement of DNA strand breakage in mammalian cells treated with bleomycin

Synergism between propolis and hyperthermal intraperitoneal chemotherapy with cisplatin on ehrlich ascites tumor in mice

We investigated antitumor, genotoxic, chemopreventive, and immunostimulative effects of local chemoimmunotherapy and hyperthermal intraperitoneal chemotherapy (HIPEC) in a mouse-bearing Ehrlich ascites tumor (EAT). Mice were treated with water-soluble derivative of propolis (WSDP) at a dose of 50 mg kg(-1) , 7 and 3 days before implantation of EAT cells, whereas cisplatin (5 or 10 mg kg(-1) ) was injected 3 days after implantation of EAT cells at 37°C and 43°C. The following variables were analyzed: the total number of cells, differential count of the cells present in the peritoneal cavity, functional activity of macrophages, comet assay, and micronucleus assay. The combination of WSDP + CIS 5 mg kg(-1) at 37°C resulted in tumor growth inhibition and increased the survival of mice by additional 115.25%. WSDP with HIPEC increased the survival of mice by additional 160.3% as compared with HIPEC. WSDP reduced cisplatin toxic and genotoxic effect to normal cells without affecting cisplatin cytotoxicity on EAT cells. In addition, WSDP with HIPEC increased the cytotoxic actions of macrophages to tumor cells. Water-soluble derivative of propolis increases macrophage activity and sensitivity of tumor cells to HIPEC and reduces cisplatin toxicity to normal cells.

Inhibition of antioxidants and hyperthermia enhance bleomycin-induced cytotoxicity and lipid peroxidation in Chinese hamster ovary cells

Regional hyperthermia has potential for human cancer treatment, particularly in combination with systemic chemotherapy or radiotherapy. Heat enhances the cytotoxic effect of certain anticancer agents such as bleomycin, but the mechanisms involved in cell killing are currently unknown. Bleomycin generates reactive oxygen species. It is likely that hyperthermia itself also increases oxidative stress in cells. We evaluate whether oxidative stress has a role in the mechanism of cell death caused by bleomycin and heat in Chinese hamster ovary cells. Heat (41 to 44 degrees C) increased cytotoxicity of bleomycin, evaluated by clonogenic cell survival. Decreased levels of cellular antioxidants should create an imbalance between prooxidant and antioxidant systems, thus enhancing cytotoxic responses to heat and to oxidant-generating drugs. We determine the involvement of four major cellular antioxidant defenses, superoxide dismutase (SOD), the glutathione redox cycle (GSH cycle), catalase, and glutathione S-transferase (GST), in cellular sensitivity to bleomycin, alone or combined with hyperthermia. These cellular defenses were inhibited by diethyldithiocarbamate, l-buthionine sulfoximine, aminotriazole, and ethacrynic acid, respectively. We show that levels of antioxidants (SOD, GSH cycle, and GST) affect cellular cytotoxic responses to bleomycin, at normal and elevated temperatures (41 to 44 degrees C), suggesting the involvement of oxidative stress. Bleomycin and iron caused oxidative damage to membrane lipids in intact cells, at 37 and 43 degrees C. Lipid peroxidation was evaluated by fluorescence detection of thiobarbituric acid-reactive products. There was an increase in damage to membrane lipids when the antioxidant defenses, SOD and catalase, were inhibited. The differing effects of antioxidant inhibitors on bleomycin-induced cytotoxicity and membrane lipid damage suggest that different mechanisms are involved in these two processes. However, free radicals appear to be involved in both cases. The marked sensitization of cells by diethyldithiocarbamate, to both bleomycin-induced cytotoxicity and lipid peroxidation, suggests that superoxide could be involved in both of these processes.

The application of hyperthermia in regional chemotherapy

To evaluate the role of hyperthermia combined with chemotherapy in the loco-regional treatment of tumors, a retrospective analysis was done with 228 limb melanoma patients treated with hyperthermic antiblastic perfusion (HAP). A series of treatment- and tumor-related prognostic factors was analyzed to establish their influence on tumor response, loco-regional control, and survival. Concerning tumor response, the logistic model showed that the number of lesions and the minimal tumor temperature (min T) maintained their individual predictive values (P < 0.000001 and P = 0.04, respectively). For loco-regional control, only the number of lesions had a significant predictive value. No direct correlation was found between the treatment-related variables and loco-regional control. However, the 5-year survival rate was significantly higher for patients who achieved a complete response (CR) (51.5%, P = 0.0033) as compared to those who did not (33.3%), providing indirect evidence of the role of the treatment. Multivariate analysis showed that both disease-free and overall survival are strongly influenced by numerous clinical variables and the min T always maintained its significance. When analyzing the subgroup of 119 patients evaluable for tumor response, the Cox model selected the tumor response as the dominant factor for both disease-free and overall survival. These data seem to demonstrate that the optimization of treatment parameters is crucial in determining the CR rate, which, in turn, positively affects the disease outcome. HAP is the treatment of choice for recurrent limb melanoma, and hyperthermia plays an important role in exploiting the efficacy of this technique.

In vitro effects of hyperthermia combined with cisplatin or peplomycin on the human maxillary carcinoma cell line IMC-2

We examined the interactive effects of hyperthermia combined with cisplatin (CDDP) (0.5 micrograms/ml) or peplomycin (PEP) (1.0 microgram/ml) on surviving fractions of human maxillary carcinoma IMC-2 cells. Either CDDP or PEP enhanced the 44 degree C thermosensitivity of thermotolerant cells after heating at 42 degrees C for 2 hours. The development of thermotolerance at 42 degrees C with either of the two drugs for 2 hours was not inhibited by CDDP, but it was partially inhibited by PEP. Moreover, for PEP throughout the entire period of 42-44 degrees C step-up heating, the 44 degree C thermosensitivity of thermotolerant cells after heating at 42 degrees C with PEP for 2 hours was enhanced similarly to that at 44 degrees C with PEP. Heating at 42 degrees C combined with either of the two drugs showed a marked interactive effect.

Hyperthermia and platinum complexes: time between treatments and synergy in vitro and in vivo

To investigate the greatest therapeutic efficacy, we investigated the effect of scheduling on the cytotoxic interaction between hyperthermia and seven different platinum complexes in vitro and in vivo using the FSaII murine fibrosarcoma cells. Hyperthermia treatment (43 degrees C, 1 h) was administered at various times relative to exposure of the cells to the IC90 (at 37 degrees C, 1 h) of each platinum complex. Greater-than-additive killing of FSaII cells was obtained with cis-diamminedichloroplatinum (II) (CDDP) and hyperthermia when the drug and heat exposure were overlapping simultaneous. The same cell killing effect with carboplatin and hyperthermia resulted from heat exposure up to 5 h prior to, simultaneous with, or immediately after the drug exposure D-Tetraplatin and K2PtCl4 were synergistic with hyperthermia only if the drug and heat exposure were simultaneous. PtCl4(Nile Blue)2 and hyperthermia produced greater-than-additive cell killing if the heat and drug exposure occurred in immediate sequence, simultaneously, or with drug exposure up to 5 h prior to heat exposure. PtCl4(Rh-123)2 and hyperthermia produced greater-than-additive cell killing if the drug and heat occurred in immediate sequence, overlapping, or simultaneously. PtCl4(Fast Black)2 and hyperthermia were additive over a wide range of scheduling from heat exposure 2 h prior to 5 h after drug exposure. When animals bearing FSaIIC tumours were treated with single doses of CDDP (10 mg/kg). carboplatin/PtCl4(Nile Blue)2 (50 mg/kg), PtCl4(Rh-123)2/PtCl4(Fast Black)2 (100 mg/kg) under various combined schedules with hyperthermia treatment (43 degrees C, 30 min), similar cytotoxicity patterns were observed. To administer hyperthermia at a time when the drug concentration in the tumour tissue is at peak level, careful scheduling of systemically administered anticancer drugs with hyperthermia is needed. Modelling studies can identify the stringency/flexibility of drug/heat scheduling to achieve synergistic tumour cell killing.

Thermal enhancement of drug uptake and DNA adducts as a possible mechanism for the effect of sequencing hyperthermia on cisplatin-induced cytotoxicity in L1210 cells

An optimal scheduling of hyperthermia and cis-diammine-dichloroplatinum(II) (cisplatin) may increase the therapeutic gain of the combination of these two modalities. In this study, intracellular platinum accumulation, total platinum binding to DNA, and DNA interstrand crosslinks (ISC) were assayed to investigate the molecular mechanisms responsible for the effect of sequencing hyperthermia on the thermal enhancement of cisplatin-induced cytotoxicity in mouse leukemia L1210 cells. Simultaneous treatment with heat (41.5 degrees C, 60 min) and cisplatin produced maximal cell killing with a 4-fold decrease in the 50% growth-inhibitory concentration (IC50) of the platinum complex. Super-additive cell killing was also shown when cells were exposed to heat before cisplatin treatment, whereas no thermal enhancement in cisplatin-mediated cytotoxicity was observed in cells given heat after exposure to cisplatin. These results correlated with the degree of formation of ISC observed in cells following various treatments. A 2- to 3-fold increase in ISC formation was observed in cells given heat before or during cisplatin exposure, whereas heat after cisplatin treatment did not alter either the formation or the reversal of ISC as compared with cisplatin alone. The increased ISC formation was associated with an increase in intracellular platinum accumulation and total platinum binding to DNA in cells given heat before or during cisplatin exposure. These data, showing that hyperthermia potentiates cisplatin cytotoxicity by increasing drug uptake and the formation of DNA adducts without inhibiting the repair of DNA lesions, demonstrate the potential utility of sequencing hyperthermia combined with cisplatin as a clinical anticancer therapy.

Haematological toxicity of carboplatin and cisplatin combined with whole body hyperthermia in rats

Acute haematological toxicity induced by cis-diammine-1,1-cyclobutane dicarboxylate platinum (II) (carboplatin) and cis-diamminedichloroplatinum (II) (cisplatin) in combination with whole body hyperthermia (WBH) (2 h at 41.5 degrees C) was examined using a F344 rat model. The thermal enhancement ratios (TERs) of drug-mediated thrombocytopenia, anaemia and leukopenia were determined from the dose-response curves of the nadir values of the peripheral platelet, RBC and WBC counts. Carboplatin produced profound depression of platelet counts which was over three-fold greater than cisplatin (14% vs 51% of the control), while the decrease in WBC and RBC counts induced by carboplatin did not differ significantly from those observed with cisplatin. These carboplatin or cisplatin-mediated haematological toxicities were significantly enhanced by WBH. The depth of decrease in platelet, RBC and WBC counts induced by the maximum tolerated dose (MTD) of carboplatin (30 mg kg-1) combined with WBH was identical to that induced by the MTD of carboplatin (70 mg kg-1) alone. The TERs of carboplatin-mediated thrombocytopenia, anaemia and leukopenia were 2.0, 2.8 and 1.9, respectively. The thermal enhancement of cisplatin mediated haematological toxicity was similar to that of carboplatin, with TERs of 1.8 for thrombocytopenia, 2.4 for anaemia and 1.9 for leukopenia. These data, demonstrating thermal enhancement of cisplatin or carboplatin-mediated haematological toxicity, must be taken into account in the clinical application of the combination therapy of platinum and WBH.

Sequence dependence of the hyperthermic potentiation of carboplatin-induced cytotoxicity and intracellular platinum accumulation in HeLa cells

We have examined the enhancement of cytotoxic effects of cis-diammine-1,1-cyclobutane dicarboxylate platinum(II) (carboplatin) by hyperthermia in HeLa cells using different regimes of timing and sequence. The results were compared with those obtained with cis-diamminedichloroplatinum(II) (cisplatin). We found that cisplatin simultaneously combined with heat was the most cytotoxic toward HeLa cells of the various timing and sequencing conditions studied. On the other hand, for carboplatin, drug treatment immediately following or during heat exposure showed the greatest effect. Intracellular platinum concentration in HeLa cells treated with heat before carboplatin showed a 2.75-fold increase over that in cells treated with the drug alone. The ratios for carboplatin given before, or during heating, were 0.67 and 1.42 respectively. Simultaneous exposure of cells to cisplatin and heat led to a 1.64-fold enhancement in cisplatin accumulation, compared to 0.92- and 1.24-fold increase for cells treated with cisplatin before and after heat respectively. Although each drug exposure prior to heat was less cytotoxic toward HeLa cells than any other heat/drug combination sequences, the platinum concentration was less than seen with each drug alone. Even though heat exposure prior to and during carboplatin showed a similar toxicity, platinum concentration in cells treated with heat prior to carboplatin was higher than that in cells treated with heat and carboplatin simultaneously. Thus, increased cytotoxicity cannot always be explained on the basis of intracellular platinum concentration. It is clear however that, differing from cisplatin, exposure of cells to heat prior to or during carboplatin administration results in the greatest cell kill.

Long-term results of postoperative intrathoracic chemo-thermotherapy for lung cancer with pleural dissemination

BACKGROUND

To overcome the poor prognosis of lung cancer with pleural dissemination, the authors developed postoperative intrathoracic chemo-thermotherapy (PICT). In this report, they present the long-term results for 31 consecutive patients who underwent resection, followed by PICT for lung cancer with pleural dissemination between April 1985 and December 1991.

METHODS

Among the patients, there were 26 cases of adenocarcinoma, 3 cases of squamous cell carcinoma, and 1 case each of large and adenosquamous cell carcinoma. Twenty-four of these patients had an initial diagnosis of pleural involvement at thoracotomy. The other seven patients had massive malignant effusion at the time of the initial diagnosis. PICT was started between days 10 to 14 postoperatively. When possible, three courses of this procedure were administered at intervals of 5-7 days.

RESULTS

The 5-year cumulative and 5-year local relapse-free survival rates were 24.6% and 76.3%, respectively. The 3-year and 5-year cumulative survival rates for 14 patients without mediastinal lymph node involvement were 68.4% and 42.7%, respectively. Those rates for 17 patients with mediastinal lymph node involvement were 22.7% and 0%, respectively. The 3-year survival rate in the former group was significantly better than that in the latter group.

CONCLUSIONS

These results strongly suggest that in patients with pleural dissemination, PICT may be beneficial for regional disease control and improvement of survival, particularly for patients without mediastinal lymph node involvement.

Modification of bleomycin-induced chromosome aberrations by hyperthermia and under energy depleting conditions in human peripheral lymphocytes

Synergistic effects of bleomycin (BLM) and hyperthermia were studied in human peripheral lymphocytes (HPL). The frequencies of breaks produced by BLM were dependent on dose, incubation temperature, and treatment time. Heat alone did not induce chromosome aberrations. Synergistic effects of heat and BLM occurred at 43 degrees C, either when hyperthermia was for 60 min following treatment with BLM or when hyperthermia was for 30 min simultaneously with BLM treatment. At incubation temperatures below 43 degrees C as many dicentric chromosomes as chromosome breaks were found, but about twice as many dicentric chromosomes as chromosome breaks were found when cells were treated with BLM at 43 degrees C for 60 min. In all experiments with BLM chromosomal anomalies were overdispersed. Comparison with unstimulated HPL, heated after X-irradiation, suggested that heat inhibits repair of BLM-induced lesions to a smaller extent than X-ray-induced lesions. Experiments with sodium azide and 2-deoxyglucose led to the conclusion that cellular uptake of BLM is partly energy-dependent. Additionally, an energy-independent uptake of BLM, which could not be blocked by inhibitors, was apparent.

Interaction between the kinetics of thermotolerance and effect of cis-diamminedichloroplatinum(II) or bleomycin given at 37 or 43 degrees C

The interaction between the cytotoxic effect of bleomycin (BLM) or cis-diamminedichloroplatinum(II) (cis-DDP) and the kinetics of thermotolerance was studied in cultured Chinese hamster ovary (CHO) cells. Pre-heated cells were treated with cis-DDP or BLM at 37 or 43 degrees C for various times after heating. Pre-heating enhanced cis-DDP cytotoxicity given immediately after heating, but this enhancement decreased within 24 h to an additive level. Cell survival following the initial heating and the second treatment of 'cis-DDP at 43 degrees C was minimal when cis-DDP at 43 degrees C was given immediately after the initial heating, but became higher with increasing treatment interval and reached 'less than additive' level when the treatment interval was extended to more than 24 h. This alteration in cell survival appeared to follow the kinetics of thermotolerance. The interaction between BLM treatment and the kinetics of thermotolerance was similar to that of cis-DDP. However, pre-heating enhanced BLM cytotoxicity much less extensively than cis-DDP cytotoxicity. These results indicate that: (a) pre-heating of cells enhanced drug-toxicity when the drug was given shortly after heating, but the magnitude of this enhancement depended on the drug; (b) pre-heating did not influence the cytotoxicity of drugs given at 37 degrees C; and (c) pre-heating decreased the magnitude of thermal sensitization of drug cytotoxicity. The magnitude of the decrease in thermal sensitization appeared to be parallel to the kinetics of thermotolerance. In this study it was also demonstrated that pre-treatment of CHO cells by cis-DDP or BLM did not alter sensitivity to subsequent drug treatment, hyperthermia or thermochemotherapy.

Schedule dependent tumour growth delay, DNA cross-linking and pharmacokinetic parameters in target tissues with cis-diamminedichloroplatinum(II) and etanidazole with or without hyperthermia or radiation

It has been reported previously that striking increases in tumour growth delay and cytotoxicity are seen when cis-diamminedichloroplatinum(II) (CDDP) is combined with mild local hyperthermia (43 degrees C, 30 min) and/or etanidazole (ETA). This paper reports a study of CDDP pharmacology and the in vivo tumour DNA cross-linking produced by these combinations. In C3H mice bearing the FSaIIC murine fibrosarcoma, Pt plasma pharmacokinetics were not significantly altered by any of the combination of treatments. Although ETA caused no significant change in CDDP tissue pharmacokinetics, treatment of the tumour-bearing limb with hyperthermia immediately following an i.p. injection of CDDP (10 mg/kg) resulted in an increased peak Pt concentration (3.5 versus 2.8 micrograms Pt/g tumour wet weight) and doubled the t1/2 elimination of Pt (15 to 30 h) from the tumour. Similar heat-induced changes were observed in the Pt pharmacokinetics in skin. There was about a three-fold increase in the Pt area under the curve (AUC) for the tumour, a 1.5-fold increase in the AUC for skin and little change in the AUC for muscle with hyperthermia. When the tumour DNA cross-linking factor (CLF) was determined, it was found that local hyperthermia treatment (43 degrees C, 30 min) increased the CLF of CDDP from 1.7 to 2.7 and hyperthermia (43 degrees C, 1 h) further increased the CLF to 6.1. Misonidazole (MISO) (1 g/kg) increased the CDDP CLF to 2.0, 6.3 and 15.1 in conjunction with 37, 43 (30 min) and 43 degrees C (1 h), respectively. ETA (1 g/kg) was more effective than MISO at increasing the CDDP CLF, producing CLFs of 2.8, 9.1 and 21.5 at 37, 43 (30 min) and 43 degrees C (1 h), respectively. These changes in CLF were reflected in an increased tumour growth delay in the FSaIIC murine fibrosarcoma with CDDP (5 mg/kg) alone from 4.4 to 5.9 days with 43 degrees C (30 min) and then to 11.9 days with ETA (1 g/kg) and 20.9 days with both ETA and local hyperthermia (43 degrees C, 30 min). When CDDP, ETA and hyperthermia were added to a radiation schedule of 300 cGy daily for five days, it was found that giving ETA (1 g/kg), CDDP (5 mg/kg) and hyperthermia (43 degrees C, 30 min) together on day 1 produced the largest tumour growth delay (43 days) and that other schedules which divided the dose of ETA over the other days of the radiation treatment (including one schedule with a second heat treatment on day 4) were significantly inferior.(ABSTRACT TRUNCATED AT 400 WORDS)

Improvement of local control by regional hyperthermia combined with systemic chemotherapy (ifosfamide plus etoposide) in advanced sarcomas: updated report on 65 patients

From July 1986 to 1990, 65 patients with deep-seated, advanced sarcomas (43 soft-tissue sarcomas, 12 Ewing's sarcomas, 7 chondrosarcomas and 3 osteosarcomas) were entered in a protocol involving regional hyperthermia (RHT) combined with systemic ifosfamide and etoposide. RHT was produced by an electromagnetic deep regional heating device (BSD Medical Corporation, Salt Lake City, Utah). Of these patients, 62% (40 patients) had received ifosfamide-containing drug regimens before entering the RHT study, 26% (17 patients) were pretreated by surgery and/or radiation and 12% (8 patients) were treated primarily. A total of 426 RHT treatments (mean 6.6 RHT/patient) were applied predominantly within the pelvic region (82%) bearing relative large tumours (mean volume 500 cm3). For systemic chemotherapy, all patients received ifosfamide (1.5 g/m2, days 1-5), etoposide (100 mg/m2, days 1, 3, 5) and 2-mercaptoethanesulphonic acid (mesna; 300 mg/m2 x 4, days 1-5) with RHT only given on days 1 and 5 in repeated cycles every 4 weeks. Detailed thermal mapping by invasive thermometry was performed in all patients. In 61 patients evaluable for tumour control the overall objective response rate including 9 complete responders (CR), 4 partial responders (PR) and 8 patients with favourable histological response (FHR) was 34% (95% confidence limits, 23%-46%). Following CR, the patients are alive and remain disease-free (mean disease-free survival 15.6 months). Of the patients with PR and FHR, 3 died from metastatic and/or local disease after 4, 17, and 39 months, and 1 patient died from other disease (acute myelocytic leukemia) after 27 months. The other 8 patients remain stable at 29, 25, 17, 11, 10, 8, 7, and 6 months. Twenty-two patients revealed no change and 18 patients showed local tumour progression (PD). Side-effects of RHT were tolerable and there was no indication of enhanced bone marrow toxicity due to the addition of RHT to the systemic chemotherapy. By analysis of temperature parameters, the time-averaged temperatures of all RHT treatments calculated for 20% (T20), 50% (T50) or 90% (T90) of measured tumour sites differed significantly between responders (CR + PR + FHR) and non-responders (PD), respectively (T20, P = 0.001; T50, P = 0.0005; T90, P = 0.0001). the data further support a strong potential for ifosfamide plus etoposide combined with RHT in pretreated patients with advanced sarcomas.

Optimisation of intraperitoneal cisplatin therapy with regional hyperthermia in rats

The purpose of this study was to optimise intraperitoneal chemotherapy by combining this modality with regional hyperthermia. In vitro data demonstrated that both the uptake of cisplatin into CC531 tumour cells and cytotoxicity were increased at temperatures of 40 degrees C (factor 4) and 43 degrees C (factor 6) compared to 37 degrees C. The increase of intracellular platinum concentration correlated well with the decrease in survival of these cells. In vivo, rats were treated intraperitoneally with cisplatin (5 mg/kg) in combination with regional hyperthermia of the abdomen (41.5 degrees C, 1 h). The mean (S.D.) temperature in the peritoneal cavity was 41.5 (0.3) degrees C and outside the peritoneal cavity 40.5 (0.3) degrees C. Enhanced platinum concentrations were found in peritoneal tumours (factor 4.1) and kidney, liver, spleen and lung (all around a factor 2.0), after combined cisplatin-hyperthermia treatment. The platinum distribution in peritoneal tumours was more homogeneous after the combined treatment than after cisplatin alone, possibly due to increased penetration of cisplatin into peritoneal tumours. Pharmacokinetic data demonstrated an increased tumour exposure for unfiltered platinum in the peritoneal cavity (area under the curve [AUC] increased from 339 mumol/l/min to 486 mumol/l/min at 37 degrees C and 41.5 degrees C, respectively), and for total and ultrafiltered platinum in the blood. The AUC for total platinum increased from 97.9 to 325.8 mumol/min and for ultrafiltered platinum from 22.2 to 107 mumol/l/min at 37 degrees C and 41.5 degrees C respectively. The latter might be due to a slower elimination of platinum from the blood. The combined treatment, intraperitoneal cisplatin and regional hyperthermia, also increased toxicity. The thermal enhancement ratio (TER) using lethality as endpoint was 1.8.

Enhanced killing of human small cell lung cancer by hyperthermia and indium-111-bleomycin complex

Indium-111-bleomycin complex (111In-BLMC) is a radiopharmaceutical agent that produces tumor regression in mouse glioma in vivo and kills human small cell lung cancer (SCLC) cells in vitro. The interaction between hyperthermia and 111In-BLMC against human SCLC (N417) cells was studied for bleomycin (BLM) (15 micrograms/ml) or 111In-BLMC (40-50 microCi carried by 15 micrograms BLM/ml) for 5 min or 1.5, 2, or 4 hr at 37 degrees C or 43 degrees C exposures. Cell survival was determined by colony formation in soft agarose. There was a synergistic effect for 111In-BLMC and hyperthermia for cell killing. At 37 degrees C, the percent survival of N417 cells for BLM alone was 25.9%, and for 111In-BLMC it was 13.2%; at 43 degrees C, survival was 5.3% for BLM alone and 1.2% for 111In-BLMC by a 4 hr treatment. Effectiveness was greater when 111In-BLMC was combined with hyperthermia.

Effect of heat on the cytotoxicity and interaction with DNA of a series of platinum complexes

The effect of elevated temperature on the cytotoxicity and interaction with DNA of a series of platinum(II) complexes was examined. CDDP showed greater enhancement in cell killing with heat than the other platinum(II) complexes. There were approximately 2 decades enhancement in cell killing by 10 microM CDDP at 42 degrees C compared to 37 degrees C. The other potential cross-linking agents also showed increasing cytotoxicity with increasing temperature. K2PtCl4 (500 microM) killed about 15 times more cells at 43 degrees C than at 37 degrees C and KPt(NH3)Cl3 (500 microM) killed about 18 times more cells at 43 degrees C than at 37 degrees C. The cytotoxicity of the triammine and tetraammine complexes was less influenced by temperature. There was no significant difference in the cytotoxicity of [Pt(NH3)3Cl]Cl at any of the temperatures examined. The cytotoxicity of [Pt(NH3)4]Cl2 (500 microM) was increased about 7-fold at 43 degrees C compared to 37 degrees C, but the total cell killing by this complex at 43 degrees C was less than 1 log. Carboplatin (250 microM) was about 5 times more toxic at 42 degrees C and killed about 2.5 decades more cells at 43 degrees C than at 37 degrees C. Although there was little enhancement in the cytotoxicity of trans-Pt(NH3)2Cl2 at 42 degrees C compared to 37 degrees C trans-Pt(NH3)2Cl2 (500 microM) was about 7 times more cytotoxic than at 37 degrees C. The interaction of the various drug/temperature treatments with supercoiled pBR322 plasmid DNA was examined to assess the effect of heat on the reaction of these agents with DNA. At 42 degrees C, CDDP was able to gradually alter the gel electrophoretic mobility of the plasmid DNA to near that of the linear form. This change also occurred at 37 degrees C but at a much slower rate. Carboplatin effected similar changes in the superhelical pBR322 DNA, and the effect of temperature appeared to increase the rate of the reaction. Trans-Pt(NH3)2Cl2 also interacted with the supercoiled DNA, but at a slower rate than CDDP even under hyperthermic conditions. These results indicate that neutral platinum complexes capable of cross-linking DNA interact positively with temperature elevation to increase cytotoxicity, and, that of the platinum complexes that meet these criteria, the effect of hyperthermia is greatest with CDDP.

Rationale for use of local hyperthermia with radiation therapy and selected anticancer drugs in locally advanced human malignancies

The addition of local hyperthermia to radiation therapy has significantly improved the ability of oncologists to control superficial malignancies. Large tumours, tumours which cannot be heated adequately, and those situated in areas where surrounding normal tissues have decreased radiation tolerance, however, are difficult to eradicate even with this combination treatment. We believe that properly selected and scheduled anticancer drugs will add substantially to the efficacy of local hyperthermia and radiation. A review of the literature concerning the cytotoxic interactions of various anticancer agents with hyperthermia, with radiation and with relevant physiological parameters is presented. From this review, anticancer drugs which are good candidates for trimodality therapy are identified and a general approach to trimodality scheduling is suggested.

Heat shock phenomena in Aspergillus nidulans. II. Combined effect of heat and bleomycin to heat shock protein synthesis, survival rate and induction of mutations

The combined action of hyperthermia and Bleomycin on Aspergillus nidulans was studied at three different levels: mycelial protein synthesis, spore viability and induction of mutations. It was found that Bleomycin treatment of preincubated mycelia during the heat shock enhances the incorporation of 35S-methionine into heat shock bands. Furthermore, simultaneous treatment with hyperthermia (43 degrees C) and Bleomycin results in greater cytotoxic activity in spores and in a higher induction rate of point mutations.

Interaction of bleomycin, hyperthermia and a calmodulin inhibitor (trifluoperazine) in mouse tumor cells

To improve the efficacy of thermochemotherapy we have investigated the individual and combined effects of hyperthermia (44 degrees C) and the calmodulin inhibitor trifluoperazine (30 micrograms/ml) on early plateau phase cultures of mouse EMT6 cells for simultaneous exposures to bleomycin. We found that a non-toxic combination of hyperthermia and trifluoperazine: enhanced the cytotoxicity of bleomycin, increased the frequency of long-lived attachment sites of cellular DNA at the nuclear matrix, and resulted in an accumulation of DNA damage (strand-breaks and alkali-labile lesions) caused by the inhibition of strand-break rejoining and the impaired processing of DNA sites involving base loss. Our findings implicate a role for calmodulin in the control of chromatin structural changes during DNA repair and the study provides a rational basis for the use of calmodulin inhibitors in thermochemotherapy.

Interaction of bleomycin, hyperthermia and a calmodulin inhibitor (trifluoperazine) in mouse tumour cells: II. DNA damage, repair and chromatin changes

We have reported in the preceding paper that the treatment of plateau phase mouse EMT6 tumour cells with a combination of hyperthermia (HT; 44 degrees C) and trifluoperazine (TFP; 30 micrograms ml-1; an inhibitor of calmodulin) greatly enhances the cytotoxicity of the antitumour drug belomycin (BLM). The cytotoxic action of BLM is thought to arise from the induction of DNA damage in a manner which reflects chromatin accessibility. Thus we have studied the effects of the two modifiers (HT and TFP) on chromatin structure and BLM-induced DNA damage. Co-treatment of cells with HT and TFP altered chromatin organisation by the formation and slow resolution of new DNA attachment sites at the nuclear matrix. HT increased drug-induced DNA damage (strand breaks and alkali-labile lesions) by the general depression of repair rather than through the generation of new sites for drug action. TFP produced a more discrete block in the repair of alkali-labile lesions in DNA. Both processes appear to occur for the combination of BLM, HT and TFP, and we propose that the novel chromatin configuration permits the accumulation of potentially lethal DNA strand breaks. Our study indicates the potential value of chromatin/DNA repair modifying regimens for overcoming the poor responsiveness of some tumour cells to chemotherapeutic drugs and provides a rational basis for the use of calmodulin inhibitors in thermochemotherapy.

Interaction of bleomycin, hyperthermia and a calmodulin inhibitor (trifluoperazine) in mouse tumour cells: I. In vitro cytotoxicity

Evidence in the literature suggests that hyperthermia (HT) or inhibitors of calmodulin can increase the sensitivity of rodent cells to bleomycin (BLM) by interfering with DNA repair functions. In an attempt to explore methods of improving the efficacy of thermochemotherapy we have investigated the individual and combined effects of HT (44 degrees C) and the calmodulin inhibitor trifluoperazine (TFP, 30 micrograms ml-1) on early plateau phase monolayer cultures of mouse EMT6 tumour cells for simultaneous exposures to BLM. Early plateau phase cultures are relatively resistant both to HT and to BLM. The selected HT and TFP regimens (either alone or in combination) were non-toxic. Comparing the sensitizing effect (given by the ratio: Do BLM/Do BLM + modifier) of the various regimens on BLM-treated cells, we found that: TFP alone had a marginal effect (ratio 1.3), HT alone showed significant potentiation (ratio 19) and the combination of HT and TFP strongly sensitized (ratio greater than 110) cells to BLM cytotoxicity. We propose that the use of calmodulin inhibitors in thermochemotherapy is worthy of further evaluation.

The interaction between bleomycin and radiation on cell survival and DNA damage in mammalian cell cultures

Chinese hamster ovary (CHO) cells were exposed to various concentrations of bleomycin (BLM) for 0.5, 1, 2, 4, 6, or 24 hours, followed with graded doses (0 to 800 rad) or radiation. The response to this chemotherapy-radiation combination treatment was measured by cell survival studies and DNA damage as determined by alkaline elution assay. Isobolograms for 1 and 2 log cell kills showed that cytotoxicity from BLM and from radiation were additive at 4, 15 and 75 milliunit/ml (mu/ml) for 1 or 4 hour exposure. When the exposure time of BLM was extended to 24 hours, slightly supraadditivity of lethality was found for the combination treatment with pharmacologically pertinent concentrations of 4 or 15 mu/ml. Therefore 4, 15 and 75 mu/ml concentrations of BLM all interacted positively with all doses of radiation to give enhanced cell kill. The alkaline elution patterns from the BLM-radiation combination also showed an enhancing effect on single strand breaks of DNA from treated cells. A human oat cell carcinoma cell line (MEMAR cells) was also studied and found to be more sensitive to BLM than were CHO cells.

A new 111In-bleomycin complex for combined radiotherapy and chemotherapy

Six days after tumor transplantation three daily intraperitoneal doses of 0.9% NaCl, bleomycin (BLM), or a new 111In-bleomycin complex (BLMC, 15 microCi/g body weight) were administered to glioma-bearing mice. After therapy, tumors in mice treated with 111In-BLMC were smaller than those treated with BLM. Sixteen days after the first injection tumor size for 111In-BLMC-treated mice was 560 (240-1,030) mm3, 1,980 (1,400-3,290) mm3 for BLM (P less than 0.025), and 4,830 (2,580-9,180) mm3 for NaCl (0.1 less than P less than 0.2). Thirteen days after tumor transplantation glioma-bearing mice received single intratumor injection of 0.9% NaCl, BLM, or 111In-BLMC (1.5 mCi, carried by 0.5 mg BLM/g tumor weight). The average tumor size for 111In-BLMC was smaller than that for BLM by a factor of 2.5-3.7. Host weights for these two groups were similar, and morphologic abnormalities were not found in kidney or liver.

Use of 111In-bleomycin for combining radiotherapy and chemotherapy on glioma-bearing mice

Mice bearing transplanted glioma received 0.9% NaCl, 0.1 mg of BLM, or 200-250 microCi of 111In-BLM (0.1 mg BLM) daily for 5 days intraperitoneally. After therapy, tumor sizes were in the order NaCl greater than BLM greater than 111In-BLM. On the 11th day after the first injection, tumor size (mm3) in the 111In-BLM group was 1,220; in the BLM group, it was 2,310 (P less than .025). After intratumor injection of a total dose of 0.1 mg of BLM/gm tumor weight, or of 1 mCi/gm tumor weight of 111In-BLM (carried by 0.1 mg of BLM/gm tumor weight), the tumor size decreased in the 111In-BLM group more than in the BLM group. On the 5th day after the 2nd dose therapy, the tumor size in the 111In-BLM group was 2,020; in the BLM group it was 4,220 (P less than .05). Host weights for these two groups were similar. The necrotic area in the tumor was much greater in the 111In-BLM group than in the BLM group. These results suggest the use for radiotherapy and chemotherapy.

Effects of 4-nitro- and 4-sulpho-7-substituted benzofurazans on nucleic acid and protein synthesis of a malignant fibrosarcoma cell line in combination with mild hyperthermia

The inhibitory effects of substituted nitro- and sulphobenzofurazans on DNA, RNA and protein synthesis were compared in a new malignant fibrosarcoma cell line at 37 degrees C and 41 degrees C. The effects of these drugs with and without mild hyperthermia were evaluated by determining the % inhibition of incorporation of 3H-precursors into DNA, RNA and protein. None of the sulphobenzofurazan derivatives (Sbf) were effective inhibitors of nucleic acid and protein synthesis at 37 degrees C nor did they enhance the inhibitory effect of hyperthermia alone. The nitrobenzofurazan derivatives (Nbf) at concentrations 10% that used for the Sbf derivatives strongly inhibited biopolymer synthesis in a dose related manner; 4-chloro-7-nitrobenzofurazan (Nbf-Cl) being the most potent inhibitor. Hyperthermia amplified the effect of all the Nbf compounds tested on RNA and protein synthesis but did not further affect DNA synthesis. This selective synergistic effect was most pronounced when the lowest concentrations of Nbf compounds were studied. The synergism however, did not follow a uniform pattern. 6-Mercaptopurine and 6-(1-methyl-4-nitro-5-imidazoyl)thiopurine (Azathioprine) (100 microM) had marginal effects on nucleic acid and protein synthesis when the cells were exposed to these two thiopurines for 1 h at both 37 degrees C and 41 degrees C and they had only a moderate inhibitory effect after exposure for 15 h.

Response of EMT6 multicellular tumour spheroids to hyperthermia and cytotoxic drugs

The response of multicellular tumour spheroids of the EMT6 cell line to combinations of hyperthermia and Bleomycin (BLM) or Adriamycin (ADM) has been investigated. Using this model system, we have demonstrated enhanced BLM cytotoxicity at 43 degrees C and also heat-induced drug tolerance to BLM at 43 degrees C. ADM cytotoxicity was not significantly increased after 43 degrees C x 1 h but after 6 h at 42 degrees C greatly enhanced cell-killing was evident. These results are discussed in relation to our previous data for EMT6 cells growing either as monolayer cultures in vitro or as solid tumours in mice.