Acceleration of late radiation damage of the kidney by unilateral nephrectomy.

Both increased proliferation as measured by labeling index and the appearance of abnormally large nuclei in renal proximal tubule cells, which have been observed in mouse kidneys after irradiation, were enhanced by subsequent unilateral nephrectomy. Nephrectomy alone induced only a transient increase in labeling index, lasting less than 1 month, whereas nephrectomy after irradiation induced an increase above that of the irradiated kidneys without nephrectomy lasting as long as 9 months. The incidence of large nuclei in kidneys from mice unilaterally nephrectomized 1 week after irradiation showed a rapid increase with time, peaking at 4.6% at 6 months, compared to more gradual increases with peaks at about 4.0% at 9 or 12 months in irradiated kidneys without nephrectomy or those in which nephrectomy was done prior to irradiation. This result demonstrates that nephrectomy after irradiation accelerates the appearance of this indicator of radiation damage, rather than enhancing the maximum amount of damage. Unilateral nephrectomy after irradiation also increased kidney damage 9 months later, as indicated by kidney weight loss and increased blood urea nitrogen. These results are consistent with our model for radiation damage of the kidney in which radiation induces cell proliferation and the appearance of reproductively dead, large nuclear cells that are lost at subsequent attempts to divide; the acceleration of radiation damage by unilateral nephrectomy performed after radiation could very well be a result of nephrectomy-induced enhancement in the proliferation of proximal tubule cells.     

脑膜瘤中c-myc和c-fos mRNA的表达及作用

为探讨ｃ－ｍｙｃ和ｃ－ｆｏｓ ｍＲＮＡ在脑膜中的作用，作者采用原位杂交结合图像分析的方法对１４例脑膜瘤中ｃ－ｍｙｃ和ｃ－ｆｏｓ的ｍＲＮＡ表达进行了定位，定量研究，结果表明杂交阳性信号均位于肿瘤细胞核周胞质中，ｃ－ｍｙｃ和ｃ－ｆｏｓ ｍＲＮＡ在脑膜瘤中的表达率分别为６４．３％和３５．７％，说明这两种癌基因表达增高在脑膜瘤发生，发展中具有重要作用。     

Expression of c-jun and c-fos in apoptotic cells after DNA damage

Apoptosis was induced in HeLa cells by exposure to 50 µM N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) for various time intervals (up to 120 min). Apoptotic death was confirmed by the microscopic observation of cell blebbing, cell granulation, and cell aggregation. Cells also showed loss of phospholipid symmetry as judged by immunofluorescent microscopy with fluorescently labeled phosphatidyl serine-specific annexin V. In addition, staining of cells with ethidium bromide showed the presence of genomic DNA apoptotic bodies. The protein expression levels of c-jun and c-fos increased in DNA-damaged HeLa cells after MNNG treatment in a time-dependent fashion. Although the levels of c-fos increased rapidly during the first 30 min and remained high for 2 hr, the increase in c-jun expression was more gradual and slower (60-120 min) after MNNG treatment. These results are consistent with the conclusion that c-fos is important in the initial stages (commitment phase) of apoptosis and c-jun is involved in the late stages (execution phase) of apoptosis induced with alkylating agents     

Expression of base excision DNA repair genes as a biomarker of oxidative DNA damage

Oxidative stress induced DNA damage is considered to be the most common insult affecting the genome. Moreover, it is recognized as a common pathway to mutations and is suggested to play a major role in the development of chronic diseases such as cancer. However, current analytical methods used to detect oxidative DNA damage have been hampered by both technical and biological obstacles. These include spurious oxidation during DNA isolation and processing, and the inherent removal of damaged bases by numerous operating DNA repair systems. The removal of oxidized bases is performed predominantly by the base excision repair (BER) pathway and it has been shown that induction of DNA repair genes occurs in response to oxidative stress. Here, we demonstrate the utility of measuring changes in expression of BER genes as a sensitive in vivo biomarker for oxidative DNA damage.     

Effects of all-trans retinoic acid as a potential chemopreventive agent on the formation of azoxymethane-induced aberrant crypt foci: Differential expression of c-myc and c-fos mrna and protein

The main objectives were to determine the modulating effects of all-trans retinoic acid on the number, size and multiplicity of aberrant crypt foci as well as the in vivo expression of the genes c-myc and c-fos. These foci, which are hypothesized to be the pre-malignant lesions of colon cancer, were induced in Sprague-Dawley rats with a single injection of azoxymethane. Rats were fed either a control diet (AIN-76) or the control diet to which had been added 75 mg/kg or 150 mg/kg all-trans retinoic acid. Within 4 weeks, we observed that the diets containing all-trans retinoic acid reduced the total number and multiplicity of aberrant crypt foci in the colon. However, all-trans retinoic acid increased the size of the lesions that persisted, possibly due to a greater proportion of lesions with dilated crypts. In situ hybridization and immunohistochemistry were performed on the colons for the in vivo analysis of gene expression in these lesions. The expression of myc-specific mRNA and protein in aberrant crypt foci significantly decreased with both levels of all-trans retinoic acid. In contrast, fos-specific mRNA and protein in aberrant crypt foci significantly increased when 150 mg/kg all-trans retinoic acid was added to the diet. The most important findings of this investigation are that intervention with all-trans retinoic acid in the pre-malignant stage of colon carcinogenesis is effective in decreasing the number and growth of aberrant crypt foci and altering the expression of the c-myc and c-fas genes.     

Early to late sparing of radiation damage to the parotid gland by adrenergic and muscarinic receptor agonists

Damage to salivary glands after radiotherapeutic treatment of head and neck tumours can severely impair the quality of life of the patients. In the current study we have investigated the early-to-late pathogenesis of the parotid gland after radiation. Also the ability to ameliorate the damage using pretreatment with adrenergic or muscarinic receptor agonists is studied. Rats were locally irradiated with or without i.p. pretreatment with phenylephrine (alpha-adrenoceptor agonist, 5 mg kg(-1)), isoproterenol (beta-adrenoceptor agonist, 5 mg kg(-1)), pilocarpine (4 mg kg(-1)), methacholine (3.75 mg kg(-1)) (muscarinic receptor agonists) or methacholine plus phenylephrine. Parotid salivary flow rate, amylase secretion, the number of cells and gland histology were monitored sequentially up to 240 days postirradiation. The effects were described in 4 distinct phases. The first phase (0-10 days) was characterised by a rapid decline in flow rate without changes in amylase secretion or acinar cell number. The second phase (10-60 days) consists of a decrease in amylase secretion and is paralleled by acinar cell loss. Flow rate, amylase secretion and acinar cell numbers do not change in the third phase (60-120 days). The fourth phase (120-240 days) is determined by a further deterioration of gland function but an increase in acinar cell number, albeit with poor tissue morphology. All drug pretreatments used could reduce radiation effects in phase I and II. The protective effects were lost during phase IV, with the exception of methacholine plus phenylephrine pretreatment. The latter combination of drugs ameliorated radiation-damage throughout the entire follow-up time. The data show that combined pre-irradiation stimulation of muscarinic acetylcholine receptors with methacholine plus alpha-adrenoceptors with phenylephrine can reduce both early and late damage, possibly involving the PLC/PIP2 second messenger pathways. This opens perspectives for the development of clinical applicable methods for long-term sparing of parotid glands subjected to radiotherapy of head and neck cancer patients.     

The potential role of HSP70 as an indicator of response to radiation and hyperthermia treatments for recurrent breast cancer

Twenty-three patients with recurrent breast cancer participating in a Phase III trial evaluating radiotherapy (XRT) with or without hyperthermia (HT) were included in a parallel study of heat shock protein (hsp) expression. The patients had core biopsies and/or fine needle aspirates (FNA) performed on their tumours, before and after treatment. These were analysed for hsp content using immunohisto-chemical staining with a monoclonal antibody to the inducible form of hspVO. The proportion of samples containing identifiable cancer cells was greater for the core biopsy specimens (80%) than with FNA (60%). Staining intensity was analysed using either the majority score, i.e. the staining intensity (on a relative scale from 0 to 3) for the largest proportion of tumour cells, or the arithmetic score, which is the sum of the product of percentage of tumour cells and their staining intensity. The staining intensity for hsp's after treatment correlated inversely with the probability of attaining a complete response (CR). Specifically, the median and maximum scores for the biopsy specimens were significantly inversely related to the probability of attaining CR. The results suggest that this technique may be useful in predicting for thermotolerance development, though more data is needed to confirm the utility of the technique. Results from this study corroborate data from other clinical studies which suggest that tumours with elevated hsp levels may demonstrate resistant biologic behaviour.     

Expression of the c-myc, c-fos and c-rasHa protooncogenes during sex-differentiated rat liver carcinogenesis in the resistant hepatocyte model

The expression of the protooncogenes c-myc, c-fos and c-rasHa has been studied in rats treated according to the resistant hepatocyte model. Protooncogene expression was studied in male and female rat liver during the selection phase, when the outgrowth of putative preneoplastic foci/nodules is markedly faster in males, and compared with the expression in advanced nodules and hepatocellular carcinomas in males. During the first 16 h after partial hepatectomy the expression of c-fos and c-myc showed transient, 2- to 3-fold, increases in both sexes, both in initiated and in 'control' animals, receiving the selection/promotion regiment but no diethylnitrosamine, with a maximum at 0.5 and 2-4 h respectively. c-rasHa exhibited a moderate increase (1.5-fold) at 16-24 h in all groups. A second increase in c-myc expression (2-fold) started 24 h after partial hepatectomy and lasted over the entire selection period in initiated males, while it was unchanged in females and uninitiated males. The c-fos expression also showed a short-lived increase 24 h post partial hepatectomy in initiated males. The expression of c-myc and c-fos was increased 2- to 4-fold in both preneoplastic nodules and hepatocellular carcinomas, whereas c-rasHa expression was unchanged. In conclusion, sex differences were observed in the expression of c-myc and c-fos during the early outgrowth of preneoplastic lesions, possibly reflecting a connection between the expression of these genes and the sex differentiated response to promotion in the resistant hepatocyte model. Furthermore, an overexpression also in later stages of liver carcinogenesis might indicate that expression of the protooncogenes in question is related to the entire process of multistep carcinogenesis in this model.     

Ionizing radiation induces alterations in cellular proliferation and c-myc, c-jun and c-fos protein expression in breast epithelial cells

The identification of genes involved in breast cancer is of critical importance in understanding the pathogenesis of the disease. Expression of the nuclear proto-oncogenes, c-myc, c-jun and c-fos, are indicative of early response events during cellular proliferation. Among them, the c-myc oncogene has been found frequently over-expressed in breast cancer. In vitro systems allow us to test the sensitivity of human breast epithelial cells to different carcinogens, including ionizing radiation. The aim of this work was to define whether these oncogenes play a functional role in radiation-induced transformation of human breast epithelial cells. We examined: a) the spontaneously immortalized MCF-10F cell line, b) clones derived from these cells treated with the carcinogen benzo(a)pyrene (BP) and then transfected with c-Ha-ras-oncogene, followed, c) by a single 3 Gy dose of gamma-rays. Protein expressions were analysed by Western immunoblot assays. Results indicated that 3 Gy dose of gamma-ray decreased the expression of these oncoproteins in the MCF-10F cells (ranging from 23 to 80%). In BP1, non-tumorigenic MCF-10F cells, radiation induced an even sharper decrease in the oncoprotein levels (ranging from 50 to 100%) relative to their non-irradiated controls. In contrast, in BP1-E tumorigenic cell line radiation increased the expression in 68-80% of c-myc, c-jun and c-fos protein expression relative to non-irradiated control. Furthermore, radiation increased c-my, c-jun and c-fos protein expression in the c-Ha-ras-3 Gy cell line relative to non-irradiated control cell line (ranging from 45 and 120%). Interesting, among the tumorigenic MCF-10F cells previously exposed to both BP and c-Ha-ras (BP1-Tras-3 Gy cell line), radiation increased the c-myc, c-jun, c-fos protein expression by more than 120% relative to the non-irradiated controls. In can be concluded that the MCF-10F model of breast carcinogenesis allows us to examine various aspects of regulations in gene expression and can provide us the basis for understanding the process of breast cancer.     

非霍奇金淋巴瘤患者骨髓垂体瘤转化基因、c-myc基因表达的研究

目的 探讨非霍奇金淋巴瘤（NHL）患者骨髓垂体瘤转化基因（PTTG）与c-myc基因的表达及其临床意义.方法 采用反转录聚合酶链反应（RT-PCR）法检测38例NHL患者骨髓及10例慢性淋巴结炎患者骨髓单个核细胞（BMMNC）中PTTG及c-myc基因的表达.结果 NHL患者骨髓中PTTG和c-myc基因的表达水平均明显高于慢性淋巴结炎组,差异有统计学意义（PTTG：0.567 7±0.270 7比0.071 2±0.020 1,t=4.706,P＜0.05; c-myc：0.352 6±0.185 4比0.107 3±0.043 5,t=3.303,P=0.002）.外周T细胞淋巴瘤和弥漫大B细胞淋巴瘤患者PTTG及c-myc基因表达水平差异均无统计学意义（PTTG：0.556 8±0.211 3比0.602 8±0.244 6,t=0.640,P=0.527;c-myc：0.350 1±0.177 6比0.361 0±0.190 2,t=0.302,P=0.765）.PTTG基因的表达与NHL骨髓浸润、国际预后指数（IPI）评分呈正相关（r=0.422,r=0.387;均P＜0.05）.c-myc基因的表达与NHL骨髓浸润、IPI评分呈正相关（r=0.431,r=0.344,均P＜0.05）.NHL患者骨髓PTTG基因和c-myc基因的表达呈正相关（r=0.490,P＜0.05）.结论 NHL中PTTG、c-myc呈高表达状态,PTTG可能通过直接或间接途径促进c-myc的高表达.     

Protection of acute and late radiation damage of the gastrointestinal tract by WR-2721

WR-2721 was investigated for its protective effect against acute and late damage produced by irradiation of the esophagus, small intestine, and colon of mice. The microcolony assay was used to measure the acute response of the small intestine and the colon, and an LD50 assay (within the 28- to 42-day time range) was used to measure acute esophageal damage. A dose of WR-2721 at 400 mg/kg, injected 30 min prior to irradiation, resulted in a protection factor (PF) of 1.6 against radiation damage in these three regions of the gastrointestinal tract. Lethality and histology scores were applied to determine late radiation damage to the rectum, at times ranging from 3 to 15 months after irradiation. Deaths occurred after doses of 20 Gy and above throughout the postirradiation period. WR-2721 increased the survival of mice; the PF calculated from the LD50 values was 1.5. PFs of animal survival did not vary during the observation period. Histological studies showed evidence of ulceration, fibrosis, and vascular changes as late radiation damage. WR-2721 protected against radiation-induced histological damage with a PF of 1.3. There was no qualitative difference between the types of histological damage observed in the group undergoing only irradiation and the group treated with WR-2721. Biochemical measurements of fibrosis by hydroxyproline determination of collagen 16 months after irradiation showed an increase in collagen per milligram wet weight of rectal tissue in all irradiated groups, but no increase in the amount of collagen per 5 mm segment of the rectum. Thus it appears that the apparent fibrosis is a result of atrophy rather than collagen accumulation. We conclude that WR-2721 is indeed effective at protection against late damage from large single doses of radiation to the rectum as measured histologically and also improves the long-term survival of the mice, although the target cells for this damage are not known.     

Acute and late radiation damage in mouse bladder: a comparison of urination frequency and cystometry

Functional damage in the mouse bladder was measured sequentially from 1 to 53 weeks after irradiation with a range of X ray doses (10 to 30 Gy). Damage was assessed from the independent assays of urination frequency and cystometric measurement of bladder volume at a constant intravesical pressure. There was an early, transient wave of damage from 1 to 3 weeks after bladder irradiation. During this period the urination frequency was increased to greater than or equal to 2 times control levels in 20 to 70% of the mice (depending on dose) after 15 to 30 Gy. Bladder volume was reduced to less than or equal to 50% of control values in 20 to 40% of the mice after doses of 20 to 30 Gy. This early damage usually lasted for less than 1 week and occurred at times ranging from 5 to 21 days, independent of dose. There was no significant correlation between response as measured by the two assays on an individual animal basis during the early period. The incidence of reduced bladder volume, measured cystometrically in anesthetized mice, tended to be less than the incidence of increased urination frequency, measured in non-anesthetized animals. Late bladder damage developed from 16 to 40 weeks after doses of greater than or equal to 20 Gy, and the time of onset was inversely related to dose. Less than 20% of mice treated with 10 to 15 Gy developed late bladder damage as assessed by increased urination frequency or reduced bladder volume. Late bladder damage was irreversible and there was a good correlation between response of individual animals as measured by the two assays. We conclude that changes in both urination frequency and bladder volume can be used as quantitative measures of early and late functional damage after bladder irradiation. The early, transient damage was not associated with changes in the urothelium or muscle layers of the bladder, whereas the late, persistent damage was accompanied by epithelial denudation and focal hyperplasia, with fibrosis and ulceration after higher doses.     

Ornithine decarboxylase induction in mouse kidney as indicator of renal damage. Differential nephrotoxic effect of anticancer antifolate drugs

High doses of folate and its quinazoline analogue with antitumour activity, N10-propargyl-5,8-dideazafolic acid (CB 3717), caused severe renal damage in mice, leading in the case of folate to death. The mouse kidneys increased in weight, which was accompanied by time- and dose-dependent induction of ornithine decarboxylase (ODC) activity. In contrast, methotrexate (MTX) had negligible effect on mouse kidneys except when applied together with the non-steroidal antiinflammatory drug, indomethacin.     

Changes in c-myc and c-fos expression in a human tumor cell line following exposure to bifunctional alkylating agents

This study was initiated to determine if DNA-damaging chemotherapeutic agents can suppress the expression of oncogenes. The effects of three structurally related bifunctional alkylating agents on the steady state mRNA levels of c-myc, c-fos, N-ras, and beta-actin in the human colon carcinoma cell line Colo320HSR were examined. Colo320HSR has an amplified c-myc oncogene, which is highly overexpressed, and is assumed to be one of the transforming genes of this cell line. Two concentrations of mechlorethamine, L-phenylalanine mustard, and 4-hydroperoxycyclophosphamide, which produced 1 or 3 log cell kills were used to examine the effects of drug exposure on the expression of specific genes. Steady state mRNA levels were measured by Northern blot analysis. Following a 1-h drug exposure, RNA was isolated from cells at 0, 6, 12, and 24 h following drug removal. The agents used produced changes in the expression of specific genes, and all three did so in a similar fashion. Immediately following drug removal, the steady state expression of c-myc in treated cells was increased 2- to 3-fold compared to control. At 6 and 12 h following drug removal, c-myc levels were depressed 2.5- to 5-fold. By 24 h, c-myc expression approached, but remained below, control levels. Immediately following drug removal, c-fos levels were increased 3- to 4-fold, and from 6 to 24 h following drug removal, c-fos levels gradually return to, or fell below low basal levels. During the 24-h time course, drug treatment had little or no effect on the steady state levels of N-ras or beta-actin. These data support the hypothesis that alkylating agents may suppress the expression of specific transforming genes.