CaMKII Met281/282 oxidation is not required for recovery of calcium transients during acidosis

CaMKII is needed for the recovery of Ca2+ transients during acidosis but also mediates postacidic arrhythmias. CaMKIIδ can sustain its activity following Met281/282 oxidation. Increasing cytosolic Na+ during acidosis as well as postacidic pH normalization should result in prooxidant conditions within the cell favoring oxidative CaMKIIδ activation. We tested whether CaMKIIδ activation through Met281/282 oxidation is involved in recovery of Ca2+ transients during acidosis and promotes cellular arrhythmias post-acidosis. Single cardiac myocytes were isolated from a well-established mouse model in which CaMKIIδ was made resistant to oxidative activation by knock-in replacement of two oxidant-sensitive methionines (Met281/282) with valines (MM-VV). MM-VV myocytes were exposed to extracellular acidosis (pHo 6.5) and compared to wild type (WT) control cells. Full recovery of Ca2+ transients was observed in both WT and MM-VV cardiac myocytes during late-phase acidosis. This was associated with comparably enhanced sarcoplasmic reticulum Ca2+ load and preserved CaMKII specific phosphorylation of phospholamban at Thr17 in MM-VV myocytes. CaMKII was phosphorylated at Thr287, but not Met281/282 oxidized. In line with this, postacidic cellular arrhythmias occurred to a similar extent in WT and MM-VV cells, whereas inhibition of CaMKII using AIP completely prevented recovery of Ca2+ transients during acidosis and attenuated postacidic arrhythmias in MM-VV cells. Using genetically altered cardiomyocytes with cytosolic expression of redox-sensitive green fluorescent protein-2 coupled to glutaredoxin 1, we found that acidosis has a reductive effect within the cytosol of cardiac myocytes despite a significant acidosis-related increase in cytosolic Na+. Our study shows that activation of CaMKIIδ through Met281/282 oxidation is neither required for recovery of Ca2+ transients during acidosis nor relevant for postacidic arrhythmogenesis in isolated cardiac myocytes. Acidosis reduces the cytosolic glutathione redox state of isolated cardiac myocytes despite a significant increase in cytosolic Na+. Pharmacological inhibition of global CaMKII activity completely prevents recovery of Ca2+ transients and protects from postacidic arrhythmias in MM-VV myocytes, which confirms the relevance of CaMKII in the context of acidosis.NEW & NOTEWORTHY The current study shows that activation of CaMKIIδ through Met281/282 oxidation is neither required for CaMKII-dependent recovery of Ca2+ transients during acidosis nor relevant for the occurrence of postacidic cellular arrhythmias. Despite a usually prooxidant increase in cytosolic Na+, acidosis reduces the cytosolic glutathione redox state within cardiac myocytes. This novel finding suggests that oxidation of cytosolic proteins is less likely to occur during acidosis.

Hypoxia-stimulated membrane trafficking requires T-plastin

AIM

Traffic between the plasma membrane and the endomembrane compartments is an essential feature of eukaryotic cells. The secretory pathway sends cargoes from biosynthetic compartments to the plasma membrane. This is counterbalanced by a retrograde endocytic route and is essential for cell homoeostasis. Cells need to adapt rapidly to environmental challenges such as the reduction of pO₂ which, however, has not been analysed in relation to membrane trafficking in detail. Therefore, we determined changes in the plasma membrane trafficking in normoxia, hypoxia, and after reoxygenation.

METHODS

Membrane trafficking was analysed by using the bulk membrane endocytosis marker FM 1-43, the newly developed membrane probe mCLING, wheat germ agglutinin as well as fluorescently labelled cholera toxin subunit B. Additionally, the uptake of specific membrane proteins was determined. In parallel, a non-biased SILAC screen was performed to analyse the abundance of membrane proteins in normoxia and hypoxia.

RESULTS

Membrane trafficking was increased in hypoxia and quickly reversed upon reoxygenation. This effect was independent of the hypoxia-inducible factor (HIF) system. Using SILAC technology, we identified that the actin-bundling protein T-plastin is recruited to the plasma membrane in hypoxia. By the use of T-plastin knockdown cells, we could show that T-plastin mediates the hypoxia-induced membrane trafficking, which was associated with an increased actin density in the cells as determined by electron microscopy.

CONCLUSION

Membrane trafficking is highly dynamic upon hypoxia. This phenotype is quickly reversible upon reoxygenation, which suggests that this mechanism participates in the cellular adaptation to hypoxia.

Normoxic destabilization of ATF-4 depends on proteasomal degradation

AIM

Hypoxia-inducible gene expression is an important physiological adaptive mechanism in response to a decreased oxygen supply. We have recently described an oxygen- and prolyl-4-hydroxylase (PHD)3-dependent stabilization of the activating transcription factor 4 (ATF-4). The aim of the present study was to examine if the normoxic destabilization of ATF-4 is regulated by oxygen-dependent proteasomal degradation.

METHODS

We determined poly-ubiquitination of ATF-4 in normoxia compared to hypoxia by immunoprecipitation and immunoblots. Furthermore, we analysed the expression of the ATF-4 target gene GADD153 as a function of oxygen concentration.

RESULTS

ATF-4 protein levels were not detectable in normoxia. Normoxic degradation correlated with an oxygen-dependent poly-ubiquitination of ATF-4, which was hindered by hypoxic incubation of the cells. As a result of hypoxia, GADD153 was expressed. The hypoxic GADD153 expression was attenuated or increased by transfecting the cells with ATF-4 siRNA or PHD3 siRNA respectively.

CONCLUSION

Our results demonstrate the involvement of oxygen-dependent proteasomal degradation of ATF-4 in the hypoxia-induced expression of GADD153. Taken together, hypoxia/PHD3-regulated stabilization of ATF-4 by hindering oxygen-dependent degradation may play a critical role in linking cell fate decisions to oxygen availability.

In vivo functions of the prolyl-4-hydroxylase domain oxygen sensors: direct route to the treatment of anaemia and the protection of ischaemic tissues

The prolyl-4-hydroxylase domain (PHD) 1-3 enzymes have been identified based on their ability to regulate the stability of hypoxia-inducible factor alpha subunits and thus to modify hypoxia-inducible gene expression. Transgenic mouse models provided insights into the isoform-specific functions of these oxygen sensors with physiological implications for angiogenesis, erythropoiesis/oxygen transport, cardiovascular function, metabolism and tissue homeostasis. This knowledge is important for the ongoing development of small molecule PHD inhibitors that are currently tested in preclinical and clinical trials for the treatment of anaemia and for cytoprotection. This review aims at summarizing the insights obtained from key mouse knock-out models as well as first experiences in the therapeutic application of PHD inhibitors.

Induction of activating transcription factor 3 by anoxia is independent of p53 and the hypoxic HIF signalling pathway

Solid tumors often have an inadequate blood supply, which results in large regions that are subjected to hypoxic or anoxic stress. Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that regulates much of the transcriptional response of cells to hypoxia. Activating transcription factor 3 (ATF3) is another transcription factor that responds to a variety of stresses and is often upregulated in cancer. We investigated the regulation of ATF3 by oxygen deprivation. ATF3 induction occurred most robustly under anoxia, is common, and it is not dependent on presence of HIF-1 or p53, but is sensitive to the inhibition of c-Jun NH2-terminal kinase activation and the antioxidant N-acetylcystein. ATF3 could also be induced by desferrioxamine but not by the mitochondrial poison cyanide or the nonspecific 2-oxoglutarate dioxygenase inhibitor dimethyloxalylglycine. We also show that anoxic ATF3 mRNA is more stable than normoxic mRNA providing a mechanism for this induction. Thus, this study demonstrates that the regulation of ATF3 under anoxia is independent of 2-oxoglutarate dioxygenase, HIF-1 and p53, presumably involving multiple regulatory pathways.

A Systemic Hyperthermia Oncologic Working Group trial. Ifosfamide, carboplatin, and etoposide combined with 41.8 degrees C whole-body hyperthermia for metastatic soft tissue sarcoma

BACKGROUND

Based on earlier clinical and preclinical studies, we conducted a phase II trial in metastatic sarcoma patients of the combination of 41.8 degrees C (x60 min) radiant heat (Aquatherm) whole-body hyperthermia (WBH) with 'ICE' chemotherapy. The ICE regimen consists of ifosfamide (5 g/m(2)), carboplatin (300 mg/m(2)) and etoposide (100 mg/m(2)), concurrent with WBH, with etoposide also on days 2 and 3 post-WBH.

METHODS

Therapy was delivered every 4 weeks for a maximum of 4 cycles. All patients received filgrastim or lenograstim.

RESULTS

Of 108 patients enrolled as of September 2001, 95 are evaluable for response. Of the evaluable patients (mean ECOG performance status approximately 1; mean age 42.3; 58% male) 33 had no prior therapy for metastatic disease, and 62 were pretreated (mean: 1.5 prior regimens). The overall response rate was 28.4% (4 complete remissions and 23 partial remissions) with stable disease (SD) in 31 patients. For no prior therapy, the response rate was 36%; in pretreated patients it was 24%. The median overall survival by Kaplan-Meier estimates was 393 days (95% CI 327, 496); the median time to treatment failure was 123 days (95% CI 77, 164). The major toxicity (287 cycles) was grade 3 or 4 neutropenia and thrombocytopenia seen in 79.7 and 60.6% of treatments respectively; there were 7 episodes of infection (grade 3/4) with 2 treatment-related deaths, bot involving disease progression and ureteral obstruction.

CONCLUSION

These results are consistent with continued clinical investigation of this combined modality approach.

Mammalian PASKIN, a PAS-serine/threonine kinase related to bacterial oxygen sensors

The PAS domain is a versatile protein fold found in many archaeal, bacterial, and plant proteins capable of sensing environmental changes in light intensity, oxygen concentration, and redox potentials. The oxygen sensor FixL from Rhizobium species contains a heme-bearing PAS domain and a histidine kinase domain that couples sensing to signaling. We identified a novel mammalian PAS protein (PASKIN) containing a domain architecture resembling FixL. PASKIN is encoded by an evolutionarily conserved single-copy gene which is ubiquitously expressed. The human PASKIN and mouse Paskin genes show a conserved intron-exon structure and share their promoter regions with another ubiquitously expressed gene that encodes a regulator of protein phosphatase-1. The 144-kDa PASKIN protein contains a PAS region homologous to the FixL PAS domain and a serine/threonine kinase domain which might be involved in signaling. Thus, PASKIN is likely to function as a mammalian PAS sensor protein.

Modulation of VP-16 cytotoxicity by carboplatin and 41.8 degrees C hyperthermia

PURPOSE

To study in vitro the effect of carboplatin and/or hyperthermia in relation to etoposide (VP-16) cytotoxicity in L929 cells.

METHODOLOGY/RESULTS

Cell survival assays demonstrated that the addition of 41.8 degrees C (x60 min) hyperthermia and carboplatin to VP-16 produced an antagonistic effect relative to VP-16 cytotoxicity in L929 cells; administering carboplatin and hyperthermia 24 h before VP-16 reduced this drug resistance; administering carboplatin and hyperthermia 48 h before VP-16, however, produced a supra-additive cytotoxicity. In order to gain insight into the molecular basis for these observations, we investigated the effect of hyperthermia and/or carboplatin on the stress protein GRP78, which is known to affect VP-16 cytotoxicity. Results obtained were consistent with the hypothesis that carboplatin and hyperthermia perturbation of NAD + pools results in down-regulation of GRP78 with subsequent modulation of VP-16 cytotoxicity. To further explicate these results we studied G-361 as a control cell line that had significantly higher pretreatment NAD+ levels, which were not affected by carboplatin and/or hyperthermia. This cell line did not exhibit a down-regulation of GRP78 or modulation of VP-16 cytotoxicity as a function of carboplatin and hyperthermia.

CONCLUSIONS

These data taken collectively, demonstrate a sequence effect (regarding the aforementioned antineoplastic agents), and provide a framework for future studies directed at the therapeutic optimization of the sequential application of carboplatin, hyperthermia, and VP-16.

A pilot study of whole body hyperthermia and carboplatin in platinum-resistant ovarian cancer

The aim of this study was to determine whether the addition of whole body hyperthermia (WBH) to carboplatin (CBDCA) can induce responses in patients with platinum-resistant ovarian cancer. 16 pretreated patients with platinum-resistant ovarian cancer were entered on a Systemic Hyperthermia Oncological Working Group (SHOWG) study; (14 patients were eligible with 14 evaluable for toxicity and 12 for response). The patients were treated with WBH (Aquatherm) 41.8 degrees C x 60 min in combination with carboplatin (CBDCA) (area under the curve (AUC) of 8) every 4 weeks. Disease status was evaluated every two cycles. Patients were treated for a maximum of six cycles. One patient had a complete response (CR) and 4 had a partial response (PR). 4 patients had stable disease (SD). 3 patients had progressive disease (PD). 2 patients were unevaluable: 1 had a bowel obstruction shortly after her first treatment; the second patient achieved a CR, but only had one treatment secondary to an idiosyncratic reaction to sedative drugs. 2 patients entered on study were ineligible, as they did not meet criteria for platinum resistance; 1 entered a CR and 1 had SD. Dose-limiting toxicity, which required CBDCA dose reductions, was grade 4 thrombocytopenia. Other toxicities included neutropenia (grade 3/4), and nausea and/or vomiting. Consistent with preclinical modelling, these results suggests that 41.8 degrees C WBH can overcome platinum resistance in ovarian cancer. These observations suggest further investigation of the therapeutic potential of WBH in a group of patients who historically fail to respond to salvage therapies is warranted.

Chronic inborn erythrocytosis leads to cardiac dysfunction and premature death in mice overexpressing erythropoietin

The most common cause of an increase of the hematocrit is secondary to elevated erythropoietin levels. Erythrocytosis is assumed to cause higher blood viscosity that could put the cardiovascular system at hemodynamic and rheological risks. Secondary erythrocytosis results from tissue hypoxia, and one can hardly define what cardiovascular consequences are caused by chronic erythrocytosis or hypoxia. Herein, a novel transgenic (tg) mouse line is characterized that is erythrocytotic because of chronic overexpression of the human erythropoietin gene. These mice grow up well, reaching a hematocrit of about 0.80 in adulthood. Blood volume of adult tg mice was markedly increased by 75%. Unexpectedly, blood pressure was not elevated and cardiac output was not decreased. Still, the adult tg mice showed features of cardiac dysfunction with increased heart weight. In vivo, high-frequency echocardiography revealed marked ventricular dilatation that was confirmed by histologic examination. Furthermore, by transmission electron microscopy, a prominent intracellular edema of the cardiomyocytes was seen. Exercise performance of the tg mice was dramatically reduced, unmasking the severity of their compromised cardiovascular function. In addition, life expectancy of the tg mice was significantly reduced to 7.4 months. Our findings suggest that severe erythrocytosis per se results in cardiac dysfunction and markedly reduced life span.

Pivotal role of reactive oxygen species as intracellular mediators of hyperthermia-induced apoptosis

The effects of cellular antioxidant capacity on hyperthermia (HT)-induced apoptosis and production of antiapoptotic heat shock proteins (HSPs) were investigated in HL-60 cells and in HL-60AR cells that are characterized by an elevated endogenous catalase activity. Exposure of both cell lines to 43 degrees C for 1 h initiated apoptosis. Apoptosis peaked at 3-6 h after heat exposure in the HL-60 cells. Whereas HL-60AR cells were partially protected against HT-induced apoptosis at these early time points, maximal levels of apoptosis were detected later, i.e. 12-18 h after heat exposure. This differential induction of apoptosis was directly correlated to the induction of the antiapoptotic HSP27 and HSP70. In particular, in the HL-60 cells HSP27 was significantly induced at 12-18 h after exposure to 43 degrees C when apoptosis dropped. In contrast, coinciding with the late onset of apoptosis in HL-60AR cells at that time HL-60AR cells lacked a similar HSP response. In line with the higher antioxidant capacity HL-60AR cells accumulated reactive oxygen species to a lesser degree than HL-60 cells after heat treatment. Protection from HT-induced apoptosis as well as diminished heat-induced HSP27 expression was also observed after cotreatment of HL-60 cells with 43 degrees C and catalase but not with superoxide dismutase. These data emphasize the pivotal role of reactive oxygen species for HT induced pro- and antiapoptotic pathways.

Whole body hyperthermia induction of soluble tumor necrosis factor receptors: implications for rheumatoid diseases

OBJECTIVE

To test the hypothesis that 41.8 degrees C x 60 min whole body hyperthermia (WBH) induces increased serum levels of soluble necrosis factor receptors (sTNF-R).

METHODS

We tested the serum of cancer patients for changes in sTNF-RI and RII levels, as a function of time, pre and post: (1) WBH alone, (2) WBH and chemotherapy, i.e., melphalan (L-PAM), and (3) L-PAM alone.

RESULTS

For sTNF-RI there was a marked increase (over pre-treatment values, i.e., 86%) in serum levels after WBH alone (n = 3), which peaked 2.5 h post-WBH; L-PAM (iv) only resulted in a dip in sTNF-RI seen 40 min postadministration; the combination (WBH + L-PAM), resulted in both the dip at 40 min and the increase at 2.5 h post-treatment. For sTNF-RII both WBH alone (n = 3) and WBH + L-PAM (n = 2), there was an increase in receptor serum levels of 25% and 30%, respectively, which peaked 5.5 h post-treatment, and remained elevated at 24 h. L-PAM alone resulted in a dip in levels only at 40 min post-treatment. sTNF-RI and RII levels returned to baseline values within 7 days post-treatment.

CONCLUSION

41.8 degrees C WBH results in transient increases in TNF-RI and RII. These results may have therapeutic implications for the application of WBH to TNF mediated disease processes.

Phase I trial of intravenous thymidine and carboplatin in patients with advanced cancer

PURPOSE

To evaluate the biologic interactions and toxicities of carboplatin combined with a 24-hour infusion of thymidine 75 mg/m(2) in a phase I trial.

PATIENTS AND METHODS

Thirty-two patients with cancer refractory to conventional therapy were treated. The first set of patients (n = 7) received thymidine alone 4 weeks before subsequent planned courses of thymidine combined with carboplatin followed (4 weeks) by carboplatin alone. Carboplatin was administered over 20 minutes at hour 20 of the 24-hour thymidine infusion. The carboplatin dose was escalated in patient groups: 200 mg/m(2) (n = 3); 300 mg/m(2) (n = 7); 350 mg/m(2) (n = 4); 400 mg/m(2) (n = 3); 480 mg/m(2) (n = 10); and 576 mg/m(2) (n = 5). At the maximum-tolerated dose (480 mg/m(2)), five patients received combined therapy first and carboplatin alone second, and five patients received carboplatin first and combined therapy second. Maintenance therapy for stable or responding patients was combined therapy.

RESULTS

Evaluation demonstrated a trend toward thymidine protection of carboplatin-induced treatment-limiting thrombocytopenia. Neutropenia with carboplatin alone or in combination was negligible. Thymidine alone had no myelosuppressive effects and produced reversible grade 1 or 2 nausea and vomiting (57%), headache (25%), and grade 1 neurotoxicity (22%). Thymidine did not enhance expected carboplatin toxicities. There was no therapy-related infection or bleeding. Analysis of platinum in plasma ultrafiltrate and urine showed no effect by thymidine. Similarly, thymidine pharmacokinetics was not affected by carboplatin. As predicted, nicotinamide adenine dinucleotide levels in peripheral lymphocytes were increased during exposure to carboplatin and/or thymidine but were decreased by carboplatin alone. In three patients with high-grade glioma, responses included one complete remission (21 months) and one partial remission (14 months) at the 480-mg/m(2)-dose level, and disease stabilization (7 months) at the 400-mg/m(2-dose) level. A minor response was observed in a patient with metastatic colon cancer (5 months) at the 480-mg/m(2)-dose level.

CONCLUSION

The combination of carboplatin and thymidine as described is well tolerated. The data presented have resulted in a phase II study by the North American Brain Tumor Consortium.

Role of tumor necrosis factor alpha in hyperthermia-induced apoptosis of human leukemia cells

We used the human myelomonoblastic leukemia cell line PLB-985 to study the effects of temperatures ranging from 37 degrees C to 43 degrees C for 1 h on the induction of apoptosis and cell cycle distribution in leukemia cells. The threshold temperature for the onset of apoptosis was 42 degrees C. Whereas hyperthermia exerted no effect on the expression of Bcl-2 and Bax, heat induced a >30-fold increase of tumor necrosis factor (TNF) alpha mRNA expression and a significant increase in TNF-alpha protein secretion. This endogenous production of TNF-alpha correlated directly with the temperature-induced apoptode effect. Blocking TNF-alpha expression via treatment with pyrrolidinedithiocarbamate or blocking TNF-alpha activity with neutralizing antibodies abrogated heat-provoked apoptosis. In addition, exposure of cell culture supernatant of heat-treated PLB-985 cells to untreated cells induced an apoptotic effect. These data indicate a TNF-a-mediated self eradication of the leukemia cells after heat exposure. Inducing apoptosis with wild-type TNF-alpha or p55 and p75 protein muteins demonstrated that this effect was mediated by the p55 receptor. Interestingly, the autocrine suicidal loop found in immature leukemia cells was lost after granulocytic differentiation with 0.5% N,N-dimethylformamide. These data should be of critical importance for the understanding of the biological impact of fever as well as for developing therapeutic approaches to malignant diseases

Whole body hyperthermia cytokine induction: a review, and unifying hypothesis for myeloprotection in the setting of cytotoxic therapy

Whole Body Hyperthermia (WBH) enhancement of chemotherapy and/or radiation without a concomitant increase in myelosuppression has been documented in clinical trials. We propose that the biological basis for this phenomena relates in part to the previously reported induction of peripheral cytokines by WBH, that is, granulocyte colony stimulating factor (G-CSF), interleukin (IL)-1 beta, IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha), and the regulatory cytokine IL-10. To further explain this myeloprotection and the additional clinical observation that WBH promotes early engraftment of bone marrow (when used as part of an allogenic bone marrow transplant preconditioning regimen) we developed a hypothesis: WBH increases peripheral IL-1 beta, IL-6, and TNF-alpha resulting in a secondary induction of IL-3 and granulocyte macrophage colony stimulating factor (GM-CSF) in the bone marrow, for which supportive data also exists. Taken collectively, these data provide an increased understanding of the biological sequelae of fever, as well as a testable unifying hypothesis, for future antineoplastic treatment strategies.

A pilot study of melphalan, tumor necrosis factor-alpha and 41.8 degrees C whole-body hyperthermia

PURPOSE

To evaluate the feasibilitv of sequencing (based on preclinical modeling) tumor necrosis factor-a (TNF) at two dose levels with melphalan (L-PAM) and 41.8 C whole-body hyperthermia (WBH) for 60 min.

PATIENTS AND METHODS

Nine patients with refractory cancer were treated from October 1995 to June 1997. The study encompassed a total of 20 trimodality treatment courses. Three patients were treated at TNF dose level I (50 microg/m2) and six patients were treated at TNF dose level II (100 microg/m2). TNF was delivered as a 24-h intravenous infusion, 48 h prior to the combination of L-PAM and WBH; L-PAM was given over 10 min at target temperature at a dose of 17.5 mg/ m2 based on a previous phase I WBH/L-PAM trial. WBH was administered with an Aquatherm radiant heat device.

RESULTS

Myelosuppression was the major toxicity associated with therapy, but there were no instances of bleeding or neutropenic fevers. Grade 3 thrombocytopenia was seen with 15% of treatments. Regarding absolute neutrophil count, 15% of treatments were associated with grade 3 toxicity, and 45% with grade 4 toxicity, and regarding white blood cell count, 50% of treatments were associated with grade 3 toxicity and 10% with grade 4 toxicity. The myelosuppression observed was equivalent to that seen in our earlier phase I study of WBH and L-PAM (without TNF). Only mild toxicities (grade 1 or 2) were associated with TNF; these were seen with <25% of treatments and included nausea, vomiting, diarrhea, fevers, and headache. There were no instances of hypotension. There was no relationship between toxicities observed and the two TNF dose levels. Mild WBH toxicities were seen with less than 15% of treatments; these included nausea, vomiting, and herpes simplex I. Responses included two complete remissions (malignant melanoma, TNF dose level I; breast cancer, TNF dose level II), and two disease stabilizations (both malignant melanoma, TNF dose level I).

CONCLUSION

We conclude that the combination of TNF, L-PAM, and WBH is well tolerated at the dose levels studied. The clinical results justify further clinical investigation for this trimodality treatment approach.

Hyperthermic modulation of SN-38-induced topoisomerase I DNA cross-linking and SN-38 cytotoxicity through altered topoisomerase I activity

The effect of different temperatures (37-42.5 degrees C) on SN-38 (the active metabolite of CPT-11) cytotoxicity was examined in the human lung carcinoma cell lines H460 and Calu-6 as well as the murine fibrosarcoma cell line L929. The cytotoxicity of SN-38, determined by MTT cell survival assay, was significantly increased in each cell line in combination with 41.8 degrees C hyperthermia (x60-120 min); the combination of SN-38 with 40.5 degrees C and 42.5 degrees C, however, was unchanged compared to 37 degrees C. Determination of topoisomerase (Topo) I DNA cross-linking in Calu-6 cells and L929 cells after treatment with SN-38 showed the same temperature profile as seen in the cell-survival assays with increased Topo I DNA cross-linking after treatment with the combination of SN-38 and 41.8 degrees C hyperthermia and unchanged Topo I DNA cross-linking at 40.5 degrees C and 42.5 degrees C. To test the hypothesis that increased Topo I DNA cross-linking and SN-38 cytotoxicity at 41.8 degrees C is caused by hyperthermia-modulated changes in Topo I activity, catalytic activity of Topo I extracted from each cell line and of purified human Topo I was determined at 20-42.5 degrees C. Topo I activity was found to be gradually increased with rising temperatures, resulting in significantly higher activity at 41.8 degrees C compared to 37 degrees C; further increase of temperature past 41.8 degrees C decreased Topo I activity back to levels found at 37 degrees C. Our data are used to explain a series of events resulting in hyperthermic enhancement of Topo I DNA cross-linking and SN-38 cytotoxicity in combination with 41.8 degrees C hyperthermia via increased Topo I activity.

Heat shock protein antibodies in sarcoma patients undergoing 41.8 degrees C whole body hyperthermia

Previous in vitro studies of sarcoma and normal cell lines exposed to 41.8 degrees C (x 60 min) demonstrated selective increased expression of members of the heat shock protein (HSP) family 70 on the cell surface of the sarcoma cells only. One implication of these data relates to the clinical application of targeting a stress-inducible, tumor-specific immune response. We therefore elected to measure immune response parameters (i.e., serum antibodies against HSP70i, 60, and 27) in six patients with sarcoma using a Western blot technique. These study patients received one to four successive 41.8 degrees C whole-body hyperthermia (WBH) x 60-min treatments (given every 3 weeks). We also tested the serum of 10 untreated healthy control subjects for the same parameters. In all patients, baseline HSP antibody levels were detectable; in no case did WBH result in an increase in HSP antibodies. The serum of one patient with sarcoma demonstrated a strong nonfluctuating reaction against HSP27 before and after WBH that had no obvious correlation; this was not observed in the sera of the control subjects. This study suggests that WBH does not induce a B-cell response to HSP family 70 antigens; these data, however, do not exclude the possibility of NK cell activation due to HSP antigen presentation.

Dynamic changes in serum erythropoietin levels in solid tumour patients undergoing 41.8 degrees C whole body hyperthermia and/or chemotherapy

Whole Body Hyperthermia (WBH) has been shown to have physiological effects on myeloid and megakaryocytic haematopoietic tissue via both cytokine induction, as well as hormonal changes. In order to extend this knowledge base to the erythroid cells, endogenous erythropoietin (EPO) levels were studied in 17 cancer patients receiving 41.8 degrees C WBH and/or chemotherapy, as well as in 53 anaemic and non-anaemic control patients. Pre-treatment EPO levels showed a 'blunted' EPO response in cancer patients compared to the control patients. Post-treatment data demonstrated a significant chemotherapy induced increase in EPO levels with a peak at 36 to 48 hours (independent of changes in haemoglobin) and 10 to 13 days post chemotherapy (simultaneously with a drop in haemoglobin levels). The early change in EPO levels was not influenced by the addition of 41.8 degrees C (x 60 min) WBH to the same chemotherapy regimen, i.e., ifosfamide, carboplatin, and etoposide. Taken collectively, our data show that endogenous EPO levels in cancer patients can be effected by chemotherapy (independent of changes in haemoglobin). This EPO response to chemotherapy is not impacted on by 41.8 degrees C WBH. A relevant secondary conclusion can also be derived from this investigation, i.e., caution should be exercised as to the use of EPO levels during chemotherapy as predictors of exogenous EPO efficacy.

Influence of circadian rhythm on 41.8 degrees C whole body hyperthermia induction of haematopoietic growth factors

It has previously been reported by the authors that the induction of a series of cytokines by 41.8 degrees C Whole Body Hyperthermia (WBH), i.e., interleukin (IL)-1 beta, IL-6, IL-8, IL-10, tumour necrosis factor alpha, and granulocyte colony stimulating factor (G-CSF). As cytokine levels are known to fluctuate as a function of time, i.e. circadian rhythm, the influence of circadian time structure on specific haemotopoetic growth factors is studied, i.e. granulocyte macrophage colony stimulating factor (GM-CSF), G-CSF and IL-3. Samples derived from four cancer patients undergoing extracorporeal WBH resulted in the following observations: G-CSF is induced by WBH, but unaffected by circadian rhythm, IL-3 fluctuates with circadian rhythm, but is unaffected by WBH. Specifically, a biphasic temporal pattern of IL-3 (i.e. with a peak at 2:00 and 5:00 a.m. and a nadir concentration at 5:00 p.m.) was found by analysis of variance. GM-CSF was below the lower detection limit pre and post WBH. The data show the importance of measuring cytokines as a function of time to circumvent conflicting results in the inter-relationship of 'true' cytokine induction and circadian rhythm. The implications of the differential induction of G-CSF, GM-CSF, and IL-3 for myeloprotection after WBH are discussed.

Lack of thermal enhancement for taxanes in vitro

The taxanes represent a new class of clinical chemotherapeutic agents. A series of in vitro studies were independently of each other initiated in two different institutes (Amsterdam and Madison) to test the hypothesis that hyperthermia might enhance the cytotoxicity of taxanes. Clonogenic capacity experiments (Amsterdam) included the exposure of R1- and SW 1573-cells to 1, 4, or 24 h of paclitaxel with heat 43 degrees C x 60 min in the last hour of drug treatment or at 24, 48 as well as 72 h post drug treatment. Survival assay experiments (Madison) included the exposure of L-929-cells to paclitaxel and docetaxel for 24 h with heat 41.8 degrees C x 60 min the first or last hour of drug treatment as well as 24 and 48 h post treatment. No thermal enhancement of cytotoxicity for the taxanes was observed in these human and murine cell lines, with congruent data in both institutes. In addition, high performance liquid chromatography studies at 41.8 degrees C and 43 degrees C demonstrated paclitaxel and docetaxel were heat stable.

Systemic hyperthermia and ICE chemotherapy for sarcoma patients: rationale and clinical status

Preclinical studies are consistent with the concept that 41.8 degrees C whole body hyperthermia (WBH) can enhance the therapeutic index of specific chemotherapeutic agents. These laboratory investigations resulted in 2 phase I clinical studies, which also support this hypothesis. These trials were extended to 2 sequential phase II investigations of WBH plus ifosfamide, carboplatin and etoposide (ICE) for refractory sarcoma patients. The first study (involving 12 patients) using extra-corporeal WBH was prematurely closed to adopt a less toxic WBH technology, i.e., the radiant heat Aquatherm. To date, 12 patients have been accrued to the Aquatherm trial. Projections regarding reduced morbidity were correct. The response rate for ICE/WBH is currently 63%. The review to follow will summarize the results of these trials, as well as the laboratory and clinical data which serve to explicate the dramatic clinical results observed to date.

Serum thrombopoietin and interleukin 6 concentrations in tumour patients and response to chemotherapy-induced thrombocytopenia

The relation between the number of platelets in blood and the concentrations of immunoreactive thrombopoietin (TPO), interleukin 6 and interleukin 11 (IL-6, IL-11) was studied in the sera of 32 normal subjects, of 29 untreated tumour patients and of 6 tumour patients following chemotherapy with ifosfamide, carboplatin and etoposide (ICE). Platelet counts, TPO and IL-6 concentrations were higher than normal in blood of tumour patients before chemotherapy. However, no statistical relation existed between these variables. Following chemotherapy, the number of circulating platelets decreased reaching a nadir at d 10-13, while the serum concentration of TPO increased concomitantly. Circulating IL-6 did not increase during chemotherapy-induced thrombocytopenia. IL-11 was not detectable in any serum. Thus, the reactive thrombocytosis in tumour patients could be related to elevated TPO and IL-6 levels. In contrast to circulating TPO, however, neither serum IL-6 nor IL-11 levels increase significantly in thrombocytopenia following myelosuppressive. chemotherapy.

Optimization of chemotherapy administration for clinical 41.8 degrees C whole body hyperthermia

Preclinical data is consistent with the concept that the timing of chemotherapy during radiant heat-whole body hyperthermia (WBH) should affect therapeutic index. In order to test this hypothesis, a controlled clinical investigation was initiated. Patients received carboplatin (CBDCA) on an early or late schedule with respect to achieving target temperature (i.e. 41.8 degrees C) in alternating treatment cycles. The first cycle was randomized between patients regarding the early or late schedule for two planned sets per patient (i.e. four cycles). Ifosfamide, etoposide and granulocyte colony stimulating factor were delivered during all cycles with a standardized schedule. A total of 53 cycles involving 17 patients were analyzed. Detailed toxicity evaluation (i.e. delay in therapy secondary to thrombocytopenia, need for platelet transfusions, and days of hospitalization) taken collectively demonstrated a statistically and clinically significant advantage to delivering CBDCA 10 min after target temperature, during the plateau phase of WBH.

In vitro studies of the hyperthermic enhancement of activated ifosfamide (4-hydroperoxy-ifosfamide) and glucose isophosphoramide mustard

PURPOSE

To study the effect of hyperthermia on the cytotoxicity of glucose isophosphoramide mustard (D-19575), a derivative of ifosfamide, which does not require activation and preclinically demonstrates less nephrotoxicity and myelosuppression than ifosfamide.

METHODS

In vitro studies (using a crystal violet cell survival assay) of the interaction of hyperthermia with D-19575, as well as the activated form of ifosfamide (4-hydroperoxy-ifosfamide, D-18851), were performed using L929 and OVCAR-3 cell lines held at various temperatures (i.e. 37 degrees C (control), 40.5 degrees C, 41.8 degrees C, 42.5 degrees C, and 43 degrees C) for 65 min.

RESULTS

The following thermal enhancement ratios (TER) were demonstrated: D-19575 in L929 1.2, 2.0 and 2.3 at 40.5, 41.8 and 42.5 degrees C, respectively; for D-18851 in L929 1.7 at 41.8 degrees C; for D-19575 in OVCAR-3 2.1, 3.2 and 3.3 at 40.5, 41.8 and 42.5 degrees C, respectively; for D-18851 in OVCAR-3 4.6 at 41.8 degrees C.

CONCLUSION

The significant observed increase in cytotoxicity of D-19575 caused by hyperthermia taken together with its known preclinical toxicity profile, encourage its further preclinical and ultimately clinical testing, including its use with whole body and regional hyperthermia.

Ifosfamide, carboplatin and etoposide (ICE) combined with 41.8 degrees C whole body hyperthermia in patients with refractory sarcoma

Two earlier studies resulted in the design of a phase II trial of 41.8 degrees C (x 60 min) extracorporeal whole body hyperthermia (WBH) with ICE, i.e. ifosfamide (5 g/m2), carboplatin (300 mg/m2), and etoposide given with WBH, as well as, day 2 and 3 post-WBH (100 mg/m2) for adult patients with refractory sarcoma. 12 patients entered this trial; all were evaluable. 8 patients had a history of prior chemotherapy associated with disease progression. Following WBH/ICE, 7 partial remissions were observed (58%); 3 patients experienced disease stabilisation; the aforementioned 10 patients each received four cycles of therapy. 2 patients exhibited progressive disease. Episodes of WHO graded (grade 3; grade 4) toxicity observed included: anaemia (2;2); leucopenia (5;7); thrombocytopenia (1;6); renal (0;1). Other toxicities (grade 1 and 2) included: anasarca, diarrhoea, ventricular arrhythmias, pressure sores, and perioral herpes simplex.

Cytokine induction by 41.8 degrees C whole body hyperthermia

The potential for 41.8 degrees C whole body hyperthermia (WBH) to enhance ionizing irradiation and cytotoxic chemotherapy without a commensurate increase in normal tissue toxicity is currently receiving renewed clinical interest. Additionally, WBH may have other biological sequela which may be clinically exploited. In this paper, data are summarized revealing the ability of WBH to induce elevated plasma levels of granulocyte-colony stimulating factor (G-CSF), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), and tumor necrosis factor-alpha (TNF-alpha) within hours of WBH. Data regarding TNF-alpha shows induction in only a proportion of patients. No induction of C-reactive protein (CRP) or the following cytokines was observed: granulocyte macrophage-colony stimulating factor (GM-CSF), interferon-gamma (IFN-gamma), interleukin-1 alpha (IL-1 alpha), interleukin-2 (IL-2), interleukin-4 (IL-4), interleukin-7 (IL-7), interleukin-11 (IL-11), interleukin-12 (IL-12), macrophage-colony stimulating factor (M-CSF), and macrophage inflammatory protein-1 alpha (MIP-1 alpha). Data regarding interleukin-3 (IL-3) and transforming growth factor-beta 1 (TGF-beta 1) were variable and inconclusive. The implications of these results to past and future clinical trials are discussed.

Influence of various factors on interferon-alpha production in cultures of human leukocytes

Inducer-specific gene loci and sex are known to play a role in the regulation of interferon-alpha (IFN-alpha) production in mice. Because little is known about the genetic control of the IFN-alpha system in man, we investigated the IFN-alpha production of 468 individuals by culturing peripheral blood with Newcastle disease virus (NDV) or Sendai virus (SDV). The IFN alpha release of different donors varied over a wide range. However, IFN-alpha production of 7 donors showed a donor-specific response over a period of 4 months, which led us to classify some donors as high and low responders. The amounts induced by NDV correlated positively to those induced by SDV. The donor's sex did not alter the IFN-alpha production significantly. The subjects were between 1 and 90 years in age. Highest IFN-alpha levels were obtained in children, followed by a gradual decline with age. Using a specific IFN-alpha-2 enzyme-linked immunosorbent assay (ELISA) and a bioassay, which detects all subtypes, our data showed that the net IFN-alpha production decreased with age. For further studies, we selected 17 low producers and 17 high producers. To analyze a possible influence of major histocompatibility complex (MHC) on IFN-alpha production, the HLA genotypes of 13 low producers and 12 high producers were determined. Here, no correlation between high or low production and HLA genotype was detectable.