Radiosensitivity: Gender and Order of Administration of G-CSF, An Experimental Study in Mice.

To elucidate the potential influence of stimulating bone marrow before cell-cycle-dependent irradiation, we sought to determine overall survival in mice receiving total-body irradiation (TBI) when administered granulocyte stimulating factor (G-CSF) at different time points. Gender differences were also studied. C57/BL/6J mice, aged 9-14 weeks, received 8 Gy TBI in a perspex cage using a linear accelerator. In each of five different experiments, three groups were studied: 1. one control group receiving TBI only; 2. one group treated with filgrastim [500 lg/kg subcutaneously/intraperitoneally (s.c./i.p.)] the day before TBI, followed by daily filgrastim injections postirradiation (1-5 days); and 3. one group treated with daily filgrastim injections only post-TBI (1-5 days). Each experimental group included male and female mice. Survival of the mice was monitored daily, and mice were euthanized when their condition deteriorated. A total of 293 mice were monitored for at least 37 days post-TBI. Control mice that received 8 Gy TBI showed a significant gender difference, with a median survival of 22 days in females and 17 days in males. Addition of G-CSF, irrespective of pre- or postirradiation, significantly improved survival, but in males the improvement was significantly better when G-CSF was not given before TBI. Improved survival in females was independent of the order of administration of GCSF. Multiple filgrastim injections were more effective than a single injection, and s.c. administration was not better than i.p. In conclusion, these findings indicate that male mice are more sensitive to TBI than females. Filgrastim improved survival in both genders irrespective of whether given pre- or postirradiation, but in males the improvement was significantly less if an injection was given before irradiation. These results suggest that, to prevent toxicity most effectively, GCSF should not be given before cytotoxic therapy. While a completely different experimental model was used here, these results may also be extrapolated to indicate that endocrine cell-cycle suppression therapy should not be given before or during cytotoxic therapy of hormone-dependent tumors (e.g., breast and prostate cancer), thus a reduction in the efficacy of cell-cycle-dependent therapy can be prevented.

Chromosomal damage in two X-ray irradiated cell lines: influence of cell cycle stage and irradiation temperature.

UNLABELLED: The aim of this study was to investigate if irradiation with X-rays in different cell cycle phases resulted in a different response as measured with the micronucleus technique. In addition, the influence of irradiation temperature was investigated. MATERIALS AND METHODS: Cells from a non-transformed human fibroblast cell line, HS2429, and a human breast cancer cell line, MCF-7, were synchronized by thymidine block and irradiated at either 2 degrees C or 37 degrees C in the G1-, S- and G2/M-phases. After cytokinesis-block by cytochalasin B, the frequency of micronuclei was determined. RESULTS: Clear dose-response relationships were found. More micronuclei were detected in fibroblast cells irradiated in G1 and S than in G2/M, while the differences were not as prominent in MCF-7 cells. The irradiation temperature had no significant influence on the formation of micronuclei in either of the cell lines. CONCLUSION: The formation of micronuclei varies with the cell cycle stage at the time of irradiation.

Vascular reactivity and perfusion characteristics in 7,12-dimethylbenz(a)anthracene-induced rat mammary neoplasia.

Blood flow during "resting conditions" and during noradrenaline infusion were studied by the labeled microsphere technique in dimethylbenz(a)anthracene-induced mammary tumors, skin, muscle, and lung in the rat. Intratumoral distribution of flow was studied by autoradiography of spheres trapped in the vascular beds of the tumors. Histological examination was performed and correlated to the blood flow data. Mean blood flow to the tumors during "resting conditions" was relatively high (49 ml/min/100 g tissue) but was substantially decreased (5 ml/min/100 g tissue) during noradrenaline infusion which produced a pressure elevation of 35 mm Hg. Thus, vascular resistance of the tumor tissue increased dramatically. Cardiac output increased, but total systemic resistance was unchanged. Vascular resistance in muscle was unchanged in contrast to an increase seen in skin. Shunted systemic blood flow to the lungs and bronchial arterial flow decreased indicating reactivity of abnormally large arteriovenous passages in the tumors. Poorly differentiated tumors had a higher vascular resistance than did well-differentiated tumors. Autoradiography revealed a nodular flow distribution with a slight tendency of higher perfusion in the periphery of these tumors.

Vascular resistance characteristics of 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors and normal tissues as studied in vitro.

Vascular perfusion characteristics have been studied in dimethylbenz(a)anthracene-induced rat mammary neoplasia and compared with those of skin, skeletal muscle, salivary gland, kidney, spleen, uterus, and brain by means of an artificial perfusion technique. Perfusion of tissues and organs was measured by the microsphere tracer technique. This procedure makes possible a detailed hemodynamic analysis of several tissues under controlled conditions, in this study maximum vascular relaxation, without confounding endogenous vasoregulation. The maximal perfusion capacity, i.e., during smooth muscle relaxation, of tumors and various tissues was related to perfusion pressure at three levels by means of three differently labeled microspheres. Tumors, especially large ones, have a low maximum perfusion capacity, i.e., high vascular resistance, compared to most other tissues. For the tumors, a relatively high perfusion pressure is required to open up the otherwise collapsed vascular network.

Vascular reactivity to norepinephrine of 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors and normal tissue as studied in vitro.

Vascular reactivity to norepinephrine has been studied in dimethyl-benz(a)anthracene-induced rat mammary neoplasia and compared with that of skeletal muscle, salivary gland, kidney, and uterus by means of an artificial perfusion technique. Perfusion of tissues and organs was measured with the microsphere tracer technique during smooth muscle relaxation and infusion of norepinephrine at two different dose levels. This procedure makes possible a dose-response analysis of several tissues under controlled conditions without confounding endogenous vasoregulation. The tumor vascular bed has a low perfusion capacity during smooth muscle relaxation and responds rapidly with an increased resistance to norepinephrine infusion. The results indicate a hypersensitivity, although the relative maximal constrictor response is equal to or less than that of other vascular beds studied.

Perfusion characteristics and norepinephrine reactivity of human renal carcinoma.

Kidneys, surgically removed due to carcinoma, were subjected to perfusion in vitro. The perfusion distribution was studied by means of labeled microspheres injected during maximal vascular dilation and during two different norepinephrine concentrations. The perfusion concluded with injection of barium sulfate. Two-mm-thick slices of tissue were autoradiographed and microangiographed for visualization of perfusion and distribution of vascular density, respectively. Multiple specimens from tumor and cortical tissues were subjected to quantitative perfusate flow analysis. In spite of regionally high vascular density, perfusion through "normal-sized" capillaries was very low in tumor tissue as compared to cortex (during maximal dilation, one-tenth of the cortical flow). During moderate norepinephrine infusion, the perfusate flow decreased, and the resistance of the cortex increased. The flow to tumor tissue increased while the vascular resistance remained constant. During higher norepinephrine concentrations, the flow was redistributed; i.e., the cortical flow increased while that of the tumor decreased, due to a marked increase in tumor vascular resistance while the cortical tissue showed a very moderate rise in resistance. The thin-walled tumor vessels might be collapsed under a high tissue pressure at low perfusion pressures. At higher perfusion pressure, the vessels might open up, and contractile activity may not be expressed until then. The tumor vascular resistance increased 3 to 4 times, while that of cortex showed a 7-fold increase. Indications that a considerable fraction of the perfusate passes arteriovenous passages larger than 15 micron were obtained in individual experiments, this fraction increasing upon norepinephrine infusion.

Effect of luteinizing hormone on respiration of the preovulatory cumulus oophorus of the rat.

The effect of luteinizing hormone (LH) on the respiration of isolated cumulus cell complexes (the oocyte surrounded by cumulus granulosa cells) obtained from immature Sprague-Dawley rats injected with 10 IU pregnant mare's serum gonadotropin on day 30 was investigated. The cell complexes were isolated from preovulatory follicles of rats killed at specific time intervals on the day preceding ovulation, i.e., on day 32. The samples were incubated in Eagle's tissue culture medium. Oxygen uptake was recorded either with the Cartesian diver technique or with a recently described microspectrophotometric technique using hemoglobin as an indicator. Exposure to exogenous bovine LH in vitro or in vivo or to endogenous LH, i.e., the preovulatory LH-surge, resulted in a marked decrease in respiratory activity of the cumulus cell complex, as revealed by both techniques. The cumuli exposed to LH showed an oxygen uptake of approximately 40-65% of the control cumuli. The results suggest that LH has a direct effect on this cell complex resulting in a decreased oxidative metabolism.

Bone marrow micrometastases in patients with stage I-II localised prostate cancer.

Prostate cancer commonly metastasises to the bones. Detection of bone marrow micrometastases (BMM) may give important information that helps define treatment strategies. This study was undertaken to analyse BMM in early prostate cancer patients and to determine the accuracy of immunohistochemical (IHC) and morphological methods in detecting cancerous cells. Preoperative core bone marrow biopsy (BMB) was performed in 103 patients with T1-2, N0, M0 prostate cancer after neoadjuvant androgen blockade. BMB were examined by IHC using monoclonal antibodies for cytokeratins (CK) (18, 19, PAN) and by cytomorphology of IHC-positive cells. In 103 patients, BMM were detected in 2 cases (2%) and an additional 3 cases (3%) were classified as suspicious. IHC alone revealed positive cells in 19 patients (18%). Cytomorphology disclosed IHC false-positive staining of some apparently normal bone marrow elements such as plasmocytes. The study shows a rather low rate of BMM in early prostate cancer. It also stresses the importance of cytomorphology as an adjunct to IHC as IHC alone may not be sufficient and appropriate for BMM detection.

Blood flow and reactivity to noradrenaline in DMBA-induced rat mammary neoplasia.

Blood flow during "resting condition' and during noradrenaline infusion were studied by microsphere tracer technique in DMBA-induced mammary tumors, hindpaw, muscle and liver in rats. During "resting condition' the mean tumor blood flow was relatively high and in the same range as that of the hindpaw representing mainly skinflow, but during noradrenaline infusion there was a marked decrease in tumor blood flow as was the case for hindpaw, while cardiac output, muscle flow and arterial liver flow remained essentially unaltered. There was an inverse relation between tumor size and blood flow.

Effects of noradrenaline on interstitial fluid pressure in induced rat mammary tumours.

Interstitial fluid pressure was measured by the wick-in-needle technique in DMBA-induced rat mammary tumours during resting conditions and during noradrenaline infusion. The rate of infusion was chosen to increase the systemic blood pressure by 30-40 mmHg, known to result in a markedly increased vascular resistance of these tumours. During resting conditions tumour interstitial fluid pressure was 10.3 +/- 1.3 mmHg (n = 13) but fell to 7.0 +/- 1.1 mmHg (n = 13) during noradrenaline infusion. The results suggests that noradrenaline is likely to affect the pre-capillary resistance vessels of the tumour vascular bed. This result, together with earlier perfusion studies, indicates that noradrenaline is unsuitable for increasing tumour cell perfusion as an adjunctive in radiation and cytotoxic drug therapy.

Bleomycin/cis-platin as neoadjuvant chemotherapy before radical radiotherapy in localized, inoperable carcinoma of the esophagus. A prospective randomized multicentre study: the second Scandinavian trial in esophageal cancer.

Survival and swallowing function were studied in a randomized trial of 97 patients with inoperable, localized esophageal carcinoma. Radical radiotherapy was given to 51 patients, while 46 patients had two courses of bleomycin/cisplatin before radiotherapy. The survival was 29% after one year, and 6% after 3 years in the radiotherapy group. The survival in the combined treatment group was 18 and 0%, respectively; p = 0.1895. The number of patients who could swallow any food increased from 6% before treatment to 38% after 3 months in the radiotherapy group, and from 0% to 23% in the combined group. No benefit was found by combining bleomycin/cisplatin with radiotherapy.

Influence of temperature on radiation-induced inhibition of DNA supercoiling.

The influence of subnormal temperatures (2, 15 and 28 degrees C) on the effects of radiation in MCF-7 cell cultures was studied using the fluorescent (halo) nucleoid assay. Increasing the propidium iodide (PI) concentration (0.5-7.5 microgram/ml PI) resulted in relaxation, i.e. in increasing nucleoid area; higher concentrations up to 50 microgram/ml caused rewinding that resulted in nucleoid contraction. Rewinding was inhibited by X irradiation (2, 4 and 8 Gy) in a dose-dependent way. Incubation at subnormal temperature did not influence the nucleoid area but did reduce radiation-induced inhibition of rewinding after 4 Gy. The low temperature (2 degrees C) during rather than prior to irradiation appeared to protect from radiation-induced inhibition of nucleoid rewinding. Decreased temperature during irradiation may change the conditions so as to reduce DNA- matrix damage induced by radiation.

Pharmacokinetics of doxorubicin and epirubicin in mice during chlorpromazine-induced hypothermia.

Blood concentrations of doxo- and epirubicin were studied in mice after i.v. or i.p. administration under normal and hypothermic conditions. The animals either were pretreated i.p. with chlorpromazine at 15 mg/kg and allowed to cool to a rectal temperature of 28 degrees C or were given saline i.p. with their rectal temperature remaining at 37 degrees C. The anthracyclines were 14-14C-labeled and were given at a dose of 0.85 mg/kg. Blood samples were taken at 5, 15, and 25 min and 2, 6, 24, and 48 hours after injection and were analyzed by liquid scintillation counting. The blood concentration related to time was similar for the two anthracyclines. The peak concentration was highest for i.v. administration and was higher for the hypothermic groups. The peak concentration and the area under the curve were highest under hypothermic conditions. The terminal half-life was longer after i.p. administration. The ratio calculated for the blood concentration under hypothermic/normothermic conditions over time was substantially increased after i.p. administration, the increase being most pronounced for epirubicin. The pharmacokinetic characteristics found might be related to the anthracycline toxicity encountered in tumor-inoculated mice treated at different body temperatures.

Acute hematologic feasibility of G-CSF supported dose-escalated FEC therapy as adjuvant treatment after breast cancer surgery.

A study of the feasibility of gradually increased epirubicin and cyclophosphamide dosage in an FEC regimen with G-CSF (granulocyte colony stimulating factor) support in 18 high-risk breast cancer patients as adjuvant treatment was carried out. The FEC regimen was initiated with 5-fluorouracil 600 mg/m2, epirubicin 75 mg/m2 and cyclophosphamide 900 mg/m2 together with G-CSF 5 micrograms/kg subcutaneously on days 2-15 q 3 weeks for nine cycles, increasing individually through four dose levels to a maximum of 5-FU 600 mg/m2 (not escalated), epirubicin 120 mg/m2 and cyclophosphamide 1800 mg/m2. Transient cytopenias were regularly observed without major clinical complications. Rapid recovery and a biphasic overshoot of granulocytes required individualization of G-CSF support. During the 6-month treatment period, a general decline in granulocytes, platelets and haemoglobin was observed, resulting in maximal dose intensity in the middle of the treatment period. Compared to a conventional FEC regimen (5-Fluorouracil 600 mg/m2, Epirubicin 60 mg/m2, Cyclophosphamide 600 mg/m2 q 3 w) without dose reductions, it was feasible to increase the dose of epirubicin by more than 50 per cent with an increased dose intensity between 25 and 70 per cent. The dose of cyclophosphamide was increased by more than 100 per cent. All patients suffered from complete alopecia and moderate nausea, but there was no acute cardiac or severe mucosal toxicity. It was concluded that intensified, G-CSF supported FEC therapy can be safely administered in an outpatient setting, provided the patients are thoroughly informed and adequately monitored. High-risk patients are enrolled in a study comparing the described regimen and a myeloablative regimen including peripheral stem-cell support. Breast cancer seems to respond to chemotherapy in a dose dependent manner, suggesting the use of dose intensified regimens (1,8,9,11). This approach is currently under investigation in studies comparing standard regimens with myelo-ablative regimens in high-risk primary breast cancer (3,10). In a Scandinavian multicenter study (2), two high dose regimens, G-CSF supported dose-escalated FEC and myeloablative cyclophosphamide-thiotepacarboplatin with peripheral stem cell support, are compared as adjuvant therapy in operable high-risk breast cancer. This phase I study was performed to assess the feasibility and achievable dose intensity of an individually dose-escalated FEC regimen not in previous use.

Hypothermic modulation of doxorubicin, cisplatin and radiation cytotoxicity in vitro.

BACKGROUND: The influence of hypothermia on doxorubicin, cisplatin and radiation cytotoxicity was investigated in vitro. MATERIALS AND METHODS: A human glioma cell line (251MG) in early exponential growth was exposed to doxorubicin or cisplatin at various concentrations for 4 hours, or X-irradiation at 28 degrees C or 37 degrees C. The cells continued growing in multi-well plates at 37 degrees C and were counted every third day until the end of the logarithmic phase, on day 13. RESULTS: Exposure to doxorubicin 0.05-0.5 microg/ml or cisplatin 1-10 microg/ml caused a dose-dependent inhibition of cell growth with a significantly reduced toxicity when exposed at 28 degrees C as compared to 37 degrees C. Irradiation with 4 Gy also resulted in less toxicity during hypothermia. Chlorpromazine 0.01-10 microg/ml, used to induce hypothermia in vivo (1), neither influenced, cellular growth itself nor interacted with doxorubicin, cisplatin or irradiation. CONCLUSION: Moderate hypothermia (28 degrees C) appears to protect against the cellular insult of doxorubicin, cisplatin and ionising irradiation and their consequences.

Vascular cross-sectional area in rat mammary tumours; influence of noradrenaline.

A double fluorescent staining technique for visualisation of blood vessels was applied to rat mammary tumours. Rats were exposed to noradrenaline or saline and the stained vascular area was recorded. In tumours exposed to noradrenaline, vascular staining was different from that in those exposed to saline, reflecting the possible closure of part of the vasculature in response to the drug.

Radio-and chemotoxicity in mice during hypothermia.

BACKGROUND: The influence of hypothermia induced by chlorpromazine (10-15 mg/kg given intra-peritoneally) on the survival from radiation and chemotherapy exposure in C57B1-mice, with or without tumour inoculation, was studied. MATERIALS AND METHODS: The mice were exposed to either whole body irradiation (8 Gy), or doxorubicin (15 or 17.5 mg/kg i.p.), or cisplatin (20 mg/kg i. p.) and followed to ensuing death. The control mice maintained a rectal temperature of 38 degres C while those receiving chlorpromazine developed moderate hypothermia of 28 degrees C or 36 degrees C, dependent on the ambient temperature. RESULTS: Hypothermia of 28 degrees C protected the mice from radiation-induced death and acute doxorubicin toxicity, with males gaining more protection than females. The effects appeared dependent on temperature, not on chlorpromazine. Hypothermia protected the mice from acute cisplatin toxicity and increased the anti-tumour effects in both genders. Chlorpromazine itself did not cause toxicity, neither did it change the natural course of tumour progression. CONCLUSION: Hypothermia of 28 degrees C induced by chlorpromazine profoundly reduces radiation, doxorubicin-and cisplatin-induced toxicity in mice with males benefiting more than females. The hypothermia itself, not the chlorpromazine, was responsible for these effects. The anti-neoplastic activity was not compromised; rather, it was enhanced, particularly for cisplatin.

Effects of oophorectomy on interstitial fluid pressure, blood flow and vascularity in a rat mammary tumour.

Interstitial fluid pressure (IFP), tumour size, blood flow and vascularity were measured in dimethyl-benz-alpha-anthracene-induced rat mammary tumours after oophorectomy. IFP was measured in the tumours by the wick-in-needle technique, blood flow by the labelled microsphere technique and vascularity by fluorescence vascular staining. Tumour volume was determined by measuring two diameters. Oophorectomy resulted in a decrease in tumour volume preceded by a decrease in IFP, while no significant change was observed in total tumour blood flow. The vascular cross-sectional area seemed to decrease. Cell proliferation may be of importance for the high interstitial fluid pressure in this hormone dependent tumour. A reduced metabolic requirement in the regressing tissue, down-regulating the vascular capacity, may camouflage the influence of the reduced tissue pressure on blood perfusion.

Effect of hypothermic irradiation of the growth characteristics of two human cell lines.

The effect of hypothermic irradiation on the growth characteristics of two human cell lines was investigated. Low temperature (2 degrees C) X-irradiation of MCF-7 cells (2, 3 and 4 Gy) resulted in higher surviving fractions compared to irradiation at 37 degrees C as assessed by the colony forming assay. The ratios for the surviving fraction between the two temperatures were 1.2, 1.5 and 1.7 at 2, 3 and 4 Gy, respectively. Correspondingly, the dose modifying factor was 1.23. The distribution of colony sizes (of those with more than 50 cells) was different with proportionally more small-sized colonies from cells irradiated at 2 degrees C. Colonies from diploid fibroblasts (HS27) were ill-defined and could not be counted. In conclusion, hypothermia during irradiation seems to influence the radioresponse in MCF-7 cells. The growth in multiwell plates of MCF-7 cells and human diploid fibroblasts (HS27) after irradiation with 3 and 4 Gy, respectively, at 2 degrees C or 37 degrees C was assessed by using the crystal violet growth assay. No difference between 2 degrees C or 37 degrees C irradiation was found for either of the two cell lines.

Growth and clonogenic assays compared for irradiated MCF-7 and Colo-205 cell lines.

Clonogenic assays have been the golden standard for the assessment of cytotoxic injury from irradiation or drugs. Since such assays are time consuming, growth assays, often with automatic quantifying equipment, are frequently used. Since these procedures do not immediately reflect loss of clonogenic capacity, it was considered important to validate the two procedures using gamma-irradiation (0, 2 and 4 Gy) of two human cell lines (MCF-7 and Colo-205). The cells were growing exponentially in 96-well plates and crystal violet staining resulted in optical densities proportional to cell number. The homogeneity of optical densities within the plates was optimal if the wells to be measured were surrounded by liquid-containing ones. The slopes of the exponential growth curves were decreased upon irradiation. An "apparent cell survival", the mean of the three lowest ratios between irradiated and control cells, was defined. It was compared with the SF2 and SF4 as found in parallel Courtenay-Mills assays. In this work we found a modest underestimation of cell survival using the growth assay, ranging from 0 to 17 per cent in absolute terms.