Article

Effect of Local X-Irradiation of a Primary Sarcoma in the Rat on Dissemination and Growth of Metastases: Dose-Response Characteristics

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Abstract

The effects of local X-irradiation of a solid, rapidly metastasizing sarcoma in the rat on kinetics of dissemination and growth of metastases in lymph nodes and lungs are described. Corresponding dose-effect curves obtained for growth of the primary tumour (Pr) and its metastases in unirradiated tissues showed that local irradiation of Pr caused an exponential decrease in growth of metastases due to any dissemination occurring after irradiation, but was also responsible for stimulating growth of metastases already established before treatment in lymph nodes and in lungs. This stimulating effect was most marked when Pr was larger at the time of treatment and when high doses were given to eradicate Pr. This effect is attributed to the liberation of growth stimulating substances (GSS) from a pool of GSS produced in the irradiated Pr by sterilized, but metabolically active and growing tumour cells (HR cells). This effect of HR cells on tumour growth and metastases was also demonstrated when rats were inoculated with viable tumour cells and subsequently treated by injecting large doses of HR cells prepared in vitro, into tissues remote from the Pr tumour site. The systemic effects of GSS on metastases were most clearly seen after immunosuppression of recipient hosts by sublethal whole body irradiation, since immunosurveillance in unirradiated rats resulting from a rapidly developing allogenic tumour-host incompatibility caused marked reductions in clonogenicity of the tumour which tended to overshadow the GSS effect. The latter was also masked in immunosuppressed hosts when excessively high rates of dissemination were due to growth of large Pr inocula for sufficiently long to “saturate” the capacity for growth of metastatic tumour in lymph nodes and lungs. The relevance of these findings to clinical radiotherapy is discussed.

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... The methods adopted to passage and inoculate the Y-P388 sarcoma, the SPF rats used for tumour growth, and the whole body and local irTadiation techniques have been described previously (van den Brenk et al., 1971; van den Brenk and Sharpington, 1972). To occlude blood flow to the tumour growing in muscle of the leg of the rat, a tourniquet was applied proximal to the tumour as described previously in mice (van den Brenk, Elliott and Hutchings, 1962) and in humans (van den). ...
... (c) Abdominal lymph node metastases (PN, UAN).-The metastases in lower abdomino-pelvic (PN) and upper abdominal (UAN) groups of lymph nodes result from cumulative growth of tumour produced by dissemination from both Pr and CN which occurs (a) in the first 48 hours after inoculation, i.e. before local irradiation of the leg and (b) after irradiation. This tumour spreads rapidly so that considerable dissemination occurs within 24,48 hours post-inoculation (van den Brenk and Sharpington, 1972). PN and UAN were shielded from exposure to irradiation so that dosage given to the leg did not affect cumulative growth of dependent reduction in dissemination showing dependence on the "oxygen effect " for spread occurring after irradiation . ...
Article
The effect of local irradiation of a rapidly metastasizing sarcoma in the leg of the rat was measured in terms of (a) regression of the primary tumour and (b) growth of metastases produced in lymph nodes and lungs, by dissemination occurring after irradiation of the primary tumour. These effects on rats which had been irradiated while breathing air were compared with rats breathing 10% O2/90% N2 in which a tourniquet had been applied proximal to the tumour to arrest blood flow during irradiation. Tourniquet anoxia increased radioresistance of growth of primary tumour by (OER) factors of 2·9-3·3. Corresponding factors for inhibition of growth of metastases in abdominal lymph nodes, and for the reduction in incidence of lung metastases produced by single tumour cells, were 2·7 and 2·4 respectively. These results suggest that this tumour was radiobiologically well oxygenated when it was irradiated in a poorly vascularized stage of growth where tumour necrosis had developed. Imagesp[404]-aFig. 1
... Numerous investigators have reported that the presence of a primary tumor inhibits growth of métastases (1, 2, 4, 5,8910 18, 20) and that its removal accelerates their growth (7-9, 12, 15, 19). The degree of inhibition varied relative to the type of tumor and its volume (6). ...
... Our observations are more in keeping with those of Rockwell and Kallman (11) who reported that there was no significant difference in either the growth rate or cell kinetics of single and multiple tumors in mice bearing a sarcoma. Numerous other investigators have also reported on the influence of a primary tumor on the growth rate of métastasesor on a second tumor transplant (1, 2,45678910161718 20). Despite their efforts, whether a primary tumor influences the growth of métastases or wee versa remains unclear because of the divergence of findings which are, in all probability, related to differences in host, tumor type, size of inoculum used, immunological variation, and other factors. ...
Article
Findings from this study using a transplantable C3H mammary tumor failed to indicate interaction relative to growth parameters between two foci present in the same host. Whether they were growing alone or in the presence of a second focus, tumor growth rates were similar until the combined mass of multiple tumors approached that which was incompatible with survival. Only then was a difference in growth observed. Cytokinetic parameters, i.e., labeling index, primer-dependent DNA polymerase index or growth fraction, DNA synthesis time, tumor doubling time, and cell cycle time, were also similar whether tumors grew alone or in the presence of a second focus. Following removal of a tumor, changes were observed within 24 hr in the kinetics of the residual focus. There was an increase in labeling index (duration approximately equal to 10 days) and primer-dependent DNA polymerase index with a decrease in the tumor doubling time. Minimal change was noted in DNA synthesis time and cell cycle time. The kinetic changes observed were reflected in a measureable increase in tumor size approximately equal to a week following tumor removal. Absence of an alteration in DNA synthesis time and cell cycle time indicates that the increase in tumor growth was probably due to a conversion of noncycling cells in G0 phase into proliferation. Relationship of the findings to the use of adjuvant chemotherapy is considered.
... This could explain why following irradiation, when the tumour mass is smaller and therefore probably releasing fewer cells systemically , the incidence of lung metastases is lowest in those mice whose tumours received the most irradiation. These data certainly do not suggest that irradiation causes either a growth stimulating substance to be produced (Van den Brenk and Sharpington, 1971), or capillary endothelial changes such that more viable cells are released systemically. From the 2000 and 5000 rad delivered to the implanted tumour, scattered doses of 44 and 1 10 rad respectively were received by the lungs. ...
Article
A slowly growing solid sarcoma was implanted subcutaneously on the anterior chest wall of mice. On reaching a predetermined size the tumours were locally irradiated using 240 kV x-rays with single doses of 0, 2000 or 5000 rad. The mice were sacrificed 12 weeks after irradiation and examined for lung metastases, which were found to be less frequent in those mice whose implanted tumours had received the most irradiation.
... Kaplan and Murphy, 1949); (ii) studies involving tumours which infiltrate diffusely rather than grow as stromated tumours (e.g. van den Brenk and Sharpington, 1971). The consensus of data from experiments which more closely simulate the majority of human cancer leads to the conclusion that the local benefits of pre-operative irradiation need not be sacrificed for fear of promoting metastases. ...
Article
An experimental tumour system for the study of metastasis has been developed using a syngeneically transplanted murine squamous carcinoma of spontaneous origin. Implants of the tumour, which does not elicit a significant immune response, grew and metastasized regularly to regional lymph nodes and lungs, in a manner comparable with that of the more malignant types of human epithelioma. The system has been used to test the influece of pre-operative irradiation, regional lymph node excision, tumour biopsy and manipulation, on metastasis. Of these, only pre-operative irradiation with 2000 rad 24 h before tumour excision produced a significant differential effect--a lower incidence of metastasis. By contrast, local radiation therapy sufficient to cause complete tumour regression but insufficient to achieve long-term local cure was shown to result in accelerated metastasis. A highly significant inhibition of metastasis was observed with the drug ICRF 159, but histological features suggested that its anti-metastatic effect in this system did not depend on morphological changes which might prevent dissemination of tumour cells. Images Fig. 4
... Other experimental studies have indicated that in many animal models, the presence of a primary tumor inhibited metastatic cell proliferation, while removal of the primary tumor accelerated metastatic cell proliferation. [10][11][12][13][14][15] About 15 years ago, Fisher et al 16,17 documented in C3H mammary adenocarcinoma that within 24 hours after the removal of a primary tumor, there was an increase in the labeling index of distant tumor foci that persisted for seven to 10 days. This probably represented conversion of noncycling cells in G 0 phase into proliferating cells. ...
... Local irradiation of the primary tumour would not directly affect these but merely allow, by delaying its growth, the expression of overt metastatic disease as recorded at PM. Such irradiation may in fact enhance the growth of already existing metastases (van den Brenk and Sharpington, 1971; Sheldon and Fowler, 1973 ). Conversely CP, alone or in combination , should exert its cytotoxic effect on both the primary and metastatic foci. ...
Article
We report observations on the spread by metastasis and infiltration of a transplantable tumour in rats treated by 60Co gamma-irradiation of the primary, irradiation plus parenteral cyclophosphamide, or parenteral cyclophosphamide alone. The proportion of animals with overt disseminated disease and the extent of spread were measured with respect to the time elapsed after implantation and treatment of the primary tumour. The incidence of metastatic disease was broadly similar for all treatment groups, but the extent of dissemination was greater in rats whose treatment included cyclophosphamide. Images Fig. 1
... If the rat was cyanosed it was placed in a chamber aerated with 95% 02/5% CO2 to recover. It was then transferred to the X-ray therapy apparatus described previously (van den Brenk and Sharpington, 1971) and the whole of the lower portion of the neck (including the entire wound) was given a single dose of 1000 rad X-rays, taking care to shield the entire thorax and remainder of the body with 3mm-thick lead sheeting. This postoperative treatment of the neck following i.t. ...
Article
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In order to elucidate the proliferation kinetics of residual tumors after surgery, experimental studies were performed, using C-1300NB and A/J mice, tumor-host system. Mice were inoculated with C-1300NB cells in the chest and leg simultaneously, and then divided into three groups. Growth curves of chest tumors (residual tumors) in Group B after amputation of the tumor-bearing leg were significantly steeper than those of both Group A, whose tumor-bearing legs were not amputated, and Group C, whose normal legs were amputated, at the same tumor age. 3H-TdR labeling indices of chest tumors of Group B were significantly higher than those of Group A (P less than 0.05). DNA histograms of the chest tumors of Group A uniformly showed a unimodal distribution with a peak in the 2c range. On the other hand, in Group B the peak of nuclear DNA distribution shifted from the 2c range to the 4c range after amputation of tumor-bearing leg. The results indicated that an increase in cells in the DNA synthetic phase occurred in the remaining neuroblastoma after reducing the volume of tumor in host by amputation of tumor-bearing legs.
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Article
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The survival and clonogenic growth (measured in terms of colony forming efficiency (CFE) of intravenously injected (i.v.) Walker (W256) tumour cells in the lungs of rats was greatly enhanced by states of topical and systemic stress induced by the intraperitoneal (i.p.) injection of rats with a single dose of 10(-5)-10(-3) mmol g-1 body weight of adrenaline and other beta-adrenergic agonists, inflammatory agents (including local x-irradiation), convulsive seizures, "tumbling" or physical restraint. Lowering of innate resistance of the host to growth of seeded tumour cells induced by states of topical and systemic stress, and by the addition of an excess of lethally irradiated (LI) tumour cells to i.v. injected intact tumour cells, were all potentiated by treatment of rats with aminophylline, an inhibitor of cyclic AMP phosphodiesterase. Enhancement of tumour growth by systemic stress was inhibited by bilateral total or medullary adrenalectomy and is attributed to the release and actions of endogenous adreno-medullary hormones. Alpha-adrenergic and most non-adrenergic agents administered in maximum tolerated doses did not significantly affect host resistance to tumour growth in the lungs. These findings, correlated with measurements of cyclic AMP in the lungs of normal and stressed rats, suggest that changes in the resistance of the host to tumour growth involve changes in cyclic nucleotide metabolism in the target tissues (tumour bed); possible mechanisms of action of cyclic nucleotides in this respect are discussed.
Chapter
Cell kinetics describe the dynamic processes involved in growth or regression of tumors in untreated hosts and in hosts perturbed by therapy or other factors. Changes in tumor volume are determined by the cell population kinetics, i.e., the length of the tumor cell cycle and its phases, the growth fraction, the rate of cell loss or cell death, and the volume of noncellular components of the tumor. The observed response of tumors to therapy is determined by all of these factors.
Chapter
At this time of increased efforts and promising results in the therapy of malignant neoplasias, it seems appropriate to review critically some principal aspects of Cell. and tissue kinetics as they relate to stem cells, to nonproliferating cells, and to Cell. recruitment into the mitotic cycle. Considering effective therapy, relatively slowly growing tumors possessing a large fraction of “nonproliferating” cells are of substantial concern. Such tumor cells, either “resting” or slowly cycling, may have an increased resistance to therapeutic agents, and some of them are probably potential stem cells. The contribution of Cell. kinetic data to planning and management of therapy of these types of cancer has not been fully adequate. Among the most likely reasons for this are the following: (1) most animal tumor systems used in cytokinetic investigations are not comparable to prevailing types of human cancer; (2) applied methods have conceptual and technical limitations; and (3) experimental approaches have usually neither allowed for any correlation between the structure of neoplastic tissues and therapeutic responses nor revealed the kinetic status of various Cell. subpopulations during the course of treatment.
Chapter
Metastatic cells originate in the primary tumor and spread widely into a variety of tissues and organs. Entering of tumor cells into the bloodstream is just the initial step in the metastatic cascade and does not necessarily result in metastatic growth. The presence of tumor cells in the circulation did not correlate with the probability of developing distant metastases in cancer patients (48). In order to establish metastatic tumors, cells also have to extravasate, survive in the new environment and proliferate there. The metastatic potency of tumor cells vary over a substantial range. In some cancer patients, highly metastatic tumor cells can develop distant metastases from very small or just histologically detectable primary tumors. Conversely, some patients bearing a huge tumor mass for years can be free from disseminated tumor nodules (58).
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The arsenal of treatments for most cancers fit broadly into the categories of surgery, chemotherapy, radiation, and targeted therapy. All represent proven and successful strategies, yet each can trigger local (tumor) and systemic (host) processes that elicit unwanted, often opposing, influences on cancer growth. Under certain conditions, nearly all cancer treatments can facilitate metastatic spread, often in parallel (and sometimes in clear contrast) with tumor reducing benefits. The paradox of treatment-induced metastasis (TIM) is not new. Supporting preclinical studies span decades, but are often overlooked. With recent evidence of prometastatic effects following treatment with targeted agents blocking the tumor microenvironment, a closer inspection of this literature is warranted. The TIM phenomena may diminish the impact of effective therapies and play a critical role in eventual resistance. Alternatively, it may simply exemplify the gap between animal and human studies, and therefore have little impact for patient disease and treatment. This review will focus on the preclinical model systems used to evaluate TIM and explore the mechanisms that influence overall treatment efficacy. Understanding the role of TIM in established and emerging drug treatment strategies may help provide rationales for future drug combination approaches with antimetastatic agents to improve outcomes and reduce resistance. Cancer Res; 75(17); 1-9. ©2015 AACR. ©2015 American Association for Cancer Research.
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To test the hypothesis that there are growth factors/cytokines released to promote healing of the wound created by the resection of a primary breast cancer which have the unintended consecuence of enabling the growth of micrometastatic foci present at the time of operation. This study was designed as a feasibility study to test whether it is technically possible to reliably assay changes in the low molecular weight serum proteome. Human xenograft breast tumors were established in 9 of 12 nude mice. Blood samples were obtained from the mice immediately prior to extirpation of the primary breast cancer and then again 24 hours, 48 hours and 7 day post-operatively. In the analysis of the serum of 5 of the mice there were 8685 peptides quantified resulting in 5949 proteins. Of these 5949 proteins 155 were identified with high confidence and 11 proteins had significant changes among the time points as a function of time pre or post-op.
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Melanomas growing in the feet of syngeneic C57BL/6 mice were treated with a single dose of X-irradiation. After doses of 0, 3.75, 7.5, 10, 20, or 30 Gy the tumor-bearing limb was amputated at tumor sizes 1, 2, 3, 4, or 5 mm. After doses of 40, 50, 62.5, or 72.5 Gy, progressive tumor growth did not occur, and amputation of tumor-bearing limbs was done when controls were 1, 2, 3, 4, or 5 mm in size. Eighteen days after amputation the mice were killed, and pulmonary metastases were documented at autopsy. None of the mice developed pulmonary metastases after curative irradiation of the primary foot tumor. After subcurative irradiation there was a significant increase (P < .003) in pulmonary metastases. The size of the primary melanoma is important in the prediction of these metastases. In this model melanomas can be cured by an adequate dose of irradiation, but in those not cured the incidence of lung metastases is increased. The impact of this biologic phenomenon on survival is unclear.
Article
Effects of local single irradiation on lung metastasis of VX2 carcinoma transplanted in maxillary sinus of rabbits were evaluated. When an inadequate irradiation for complete regression was given, the rate of pulmonary metastases in irradiated groups was remarkably increased compared with non-irradiated one, although tumor growths in irradiated ones were apt to be inhibited corresponding to the given dose. Three parameters detected in the study related to general conditions were not so significantly different among the groups although those in irradiated groups were apt to be worse than those in control. Histologically most remarkable difference between in control and irradiated groups was stromal respose. However, on the question of whether stromal response could react as a diffensive or promotive mechanisms against tumor metastases, further studies would be needed including analysis of infiltrative cells.
Article
This chapter summarizes the findings and hypotheses of cancer metastasis and elucidates the complex mechanisms involved in the pathogenesis of metastasis. The development of a metastasis is dependent on the interplay of host and tumor cell properties. The process is complex, highly selective, and represents the end stage of several destructive events from which few tumor cells survive. Malignant neoplasms may consist of a variety of subpopulations of cells with differing capabilities for invasion and metastasis. Only a few tumor cells within a primary neoplasm may actually invade blood vessels, and of those, even fewer survive in the circulation. The unique characteristics of tumor cells, including modifications in cell surface properties, adhesive capacities, cell motility, and enzyme secretion, are of paramount importance in determining the eventual outcome of the metastasis. Such acquired properties of malignant cells allow for interaction with host tissues and cells, which leads to tumor cell survival and growth. Three mechanisms are invoked to explain tumor cell invasion—(1) the rapid multiplication of malignant cells leading to growth and infiltration by mechanical pressure, (2) the destruction of host tissue by the products of the tumor cell, and (3) the lack of tumor cell adhesiveness accompanied by an increase in the cell motility.
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Despite the fact that preoperative chemotherapy causes substantial necrosis in the primary osteosarcoma tumor, most authorities recommend resecting these lesions with a wide margin of normal tissue to avoid local recurrence. This study evaluated the effect of systemic chemotherapy (doxorubicin) on tumor growth and histology in the MGH-OGS transplantable murine model and examined whether this drug prevents local recurrence after resection of the tumor with positive microscopic margins. The results indicate that doxorubicin caused prolonged cessation of tumor growth, produced substantial necrosis within the lesion, and decreased the risk of local relapse following marginal surgery. The drug effect was dose-dependent and drug efficacy in preventing local relapse was maximal with administration prior to or at the time of surgery.
Article
In this review, the various ways are examined by which combined modality regimens can affect the host in such a manner as to modify the outcome of the therapy. These host changes are considered under the general headings of effects on (1) drug pharmacokinetics, (2) vasculature, (3) the specific immune response, (4) non-specific host defenses, particularly those mediated by macrophages, (5) general host condition, and (6) a miscellaneous category including local infection and drug-stimulated recovery of surviving cells. Where appropriate, the relative influence is examined of each of these host effects on the commonly used endpoints for assay of tumor response. In general, the assays most likely to be affected are those in which the tumor remains in situ after treatment (tumor cure, regrowth delay, and, the most limited endpoint, increase in lifespan). However, assays for cell survival by removal of the tumor soon after treatment are not entirely free from possible host effects. A possible outcome of several different host effects is a change in the metastatic frequency of the tumor. This may have little or no effect on the "therapeutic ratio" judged in terms of local effect, but could have a large influence of the overall efficacy of a particular regimen. Since host effects are likely to be rather specific to the particular model system employed, they usually represent an unwanted side-effect of the treatment which may interfere with, or alter, interpretations of the experimental data. For this reason a list of precautions in the selection and use of experimental systems is given in the results. These include measurement of tumor drug levels, use of non-immunogenic tumor/host models, and the avoidance of stress, excessive weight loss, local infection, and the use of anesthetics for animal immobilization.
Article
The immune system is believed to influence tumor growth; and, ionizing radiation has an immunosuppressive potential. However, investigators have come to conflicting conclusions regarding the effect of localized radiation therapy on both the immune system and on distant tumor growth.This report describes two murine models. In the first, B-16 malignant melanoma was implanted simultaneously into the left groin and right axilla. In the second model, in order to immunize the mouse, B-16 melanoma was implanted into the left groin 1 week before implanting melanoma into the right axilla. In both models, 600 rad caudal hemibody irradiation was given in a single fraction with a 4 MeV linear accelerator. Significant decrease in the growth of irradiated groin tumors occurred. Unirradiated axillary tumors did not demonstrate increased growth.We conclude that, at least in these models, high dose, wide-field irradiation does not augment the growth of unirradiated tumors in the same host.
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The incidence and growth is reported of local recurrence and metastases - to axillary, inguinal, para-aortic nodes, lungs, thymus and adrenals - from a spontaneous breast carcinoma transplanted subcutaneously into 172 isologous 150-200 g virgin female Wistar rats. Of 28 controls, 45% developed metastases. In 145, after excision of the tumour at 1 to 28 days, 9% developed recurrence, 12% recurrence and metastases, 31% metastases alone, and 48% remained tumour-free. After excision at 1-8 days, local recurrence and metastases were 10%, but increased to 50% at 12 days. After surgery at 15 to 28 days, local recurrence was reduced to 10%, but metastases occurred in about 90% of animals. The average number of sites with metastases was 2.5 per affected animal, and was independent of the time of surgery. Local recurrent tumours and metastases in axilla and inguina grew at the same rate as the primary in control animals, but metastases at other sites either grew more slowly or arose later.
Article
Surgical and chemotherapeutic effects on pulmonary metastatic disease were evaluated in the MGH-OGS murine osteosarcoma. The tumor responded to three sequential injections of doxorubicin with prolonged growth delay but cisplatin administration (although given in doses sufficient to cause weight loss and significant mortality) was not effective in controlling local disease progression. Using a protocol with three injections of doxorubicin (0.006 mg/g of body weight), it was observed that disease-free survival was enhanced when one of the three doses of doxorubicin was given at the time of surgery (perioperatively). By marginally resecting the primary tumor and permitting its regrowth, a model was developed with recurrent primary and metastatic disease present simultaneously. It was observed in this model that amputation or resection of the recurrent primary lesion resulted in pulmonary metastatic growth acceleration. Using this recurrent primary tumor model, doxorubicin's effect on pulmonary metastatic lesions was enhanced when the drug was given at the time of amputation.
Chapter
The prostaglandins are ubiquitous tissue hormones which are bio synthesized from essential unsaturated fatty acids such as arachidon acid in response to a variety of stimuli, and rapidly inactivated by catabolic enzymes. Many tumours particularly medullary carcinoma of the thyroid and other amine peptide-secreting tumours produce important quantities of prostaglandins which give rise to some of th clinical symptoms such as attacks of flushing and diarrhoea (1). Other carcinomas whether primary or secondary also produce prostaglandins (2). The primary prostaglandins produced are of the E series particularly PGE2. It is interesting to note that many of the changes associated with prostaglandins are in fact diametrically opposite to those that take place during tumour growth (2). (a) While PGE’s promote morphological differentiation of malignant cells, dedifferentiation is a characteristic feature of maligna transformation. (b) Prostaglandins particularly of the E series inhibit tumour grow (3) and may actually act to restrain growth of some tumours since low doses of indomethacin, an inhibitor of the prostaglandin synthetase complex, stimulate tumour growth.
Article
Virtually every modality employed in the treatment of cancer has demonstrated an adverse effect upon metastasis under some conditions. This review surveys the experimental and clinical literature pertaining to the untoward effects of ionizing radiation upon metastatic processes. Two processes are described: (1) enhancement of metastases following local tumor irradiation; (2) localization of metastasis in previously irradiated normal tissues. In the first process the experimental evidence indicates a local effect of irradiation upon the tumor-stroma interface. It predominates under conditions of non-curative radiation doses. There is no proof that this process occurs in clinical practice, but a review of data provides suggestive evidence for its existence following non-curative therapy. The second process is documented both experimentally and clinically. It requires the presence of viable, circulating tumor cells and appears mediated through vascular damage. The few clinical reports suggest that this effect is rare in practice. The clinical significance of both processes appears small under conditions of effective tumor therapy, but it is speculated that inadequate tumor irradiation, or irradiation of normal tissues with uncontrolled tumor elsewhere, may be deleterious.
Article
To investigate the effect of radiation on E-cadherin and alpha-catenin expression in a human lung cancer cell line, and also evaluate invasive capacity in the membrane invasion culture system using the Boyden Chamber. The immunoblot and immunofluorescence analyses were performed using the human lung cancer cell line A549 to examine altered expression of E-cadherin and alpha-catenin after irradiation. We also compared invasive capacity of untreated cells with that of irradiated cells. Immunoblot analysis revealed that the expression of E-cadherin increased after irradiation. In a time-course analysis, the expression was increased 6 h after irradiation with 10 Gy and reached its peak level at 24 h, being 2.3 times the control value, whereas expression at 1 and 3 h after irradiation was almost equivalent to that of the control. A slight increase in expression was observed after irradiation of 2 Gy and the expression reached peak levels after 5 Gy. After fractionated irradiation, the increase in expression of both E-cadherin and alpha-catenin was observed, and the alteration of alpha-catenin was more prominent than that after a single irradiation of the same total dose. In the immunofluorescence study for E-cadherin antibody analyzed by confocal laser scanning microscopy, increased intensity in irradiated cells produced as a nondisrupted and continuous line at cell-cell contact sites. In an invasive assay, the number of migrated cells in irradiated cells after a dose of 5 and 10 Gy was reduced significantly compared to untreated cells. The results indicate that irradiation of A549 increased the expression of E-cadherin, possibly preserving their functional property.
Article
The growth of an allogeneic rapidly growing and metastasizing sarcoma (P-388) in the rat is described. Quantitative and kinetic data are provided concerning the growth of individual metastases produced in three principal regional lymph node drainage groups, and are compared with growth of the primary tumour of origin in muscle, the incidence of pulmonary metastases is also given. The effects on growth of metastases and primaries produced by sublethal whole body irradiation (WBI) before inoculations of 10-10⁸ tumour cells are described.
Article
The effects of x-irradiation have been quantitatively studied on single cells of a human cervical carcinoma (HeLa) under conditions such that 100 per cent of the unirradiated cells reproduce in isolation to form macroscopic colonies. This technique eliminates complexities due to interactions of members of large cell populations. Survival of single cells (defined as the ability to form a macroscopic colony within 15 days) yields a typical 2 hit curve when plotted against x-ray dose. The initial shoulder extends to about 75 r, after which a linear logarithmic survival rate is obtained, in which the dose needed to reduce survivors to 37 per cent is 96 r. This radiation sensitivity is tens to hundreds of times greater than that of any microorganism for which the equivalent function bas been studied. Evidence, though not proof, is presented that the lethal effect is due to a radiation-induced genetic defect which, however, cannot be a simple single gene inactivation. The locus of the action could be chromosomal. Beginning at doses of 100 r, or possibly earlier, growth-delaying effects of radiation are visible. Cells in which the ability to reproduce has been destroyed by doses below 800 r, can still multiply several times. At higher doses even a single cell division is precluded. A large proportion of the cells killed by radiation at any dose gives rise to one or more giant cells. These metabolize actively, grow to huge proportions but never reproduce under the experimental conditions employed. Methods of preparing large populations of giant cells are described. These giants are particularly susceptible to virus action. Some of the irradiated cells disappear from the plate, presumably by disintegration. This action of radiation is by far the least efficient, since even after 10,000 r, 5 to 10 per cent of the original cell inoculum is recoverable as giants.
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