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Experimental murine model of renal cancer
Abstract
Introduction
The objective of this study was to determine the reproducibility in a murine model of renal tumors of various histological strains that could be useful for investigating the response to target drugs.
Material and methods
Development and analysis of the “in vivo” model: tumor xenograft of renal cell carcinomas with Balb/c nude athymic mice. Nontumourous human renal tissue was implanted in the interscapular region of 5 mice, chromophobe renal cell carcinoma was implanted in 5 mice (which, after checking its growth, was prepared for implantation in another 10 mice) and Fuhrman grade 2 clear cell renal cell carcinoma (CCRCC) was implanted in 5 mice (which was also subsequently implanted in 10 mice).
We monitored the tumor size, onset of metastases and increase in size and number of tumors. When the size had reached a point greater than or equal to locally advanced or metastatic carcinoma, the animals were euthanised for a pathological and immunohistochemical study and a second phase of implantation.
Results
The subcutaneous xenograft of the healthy tissue did not grow. The animals were euthanised at 6 months and no renal tissue was found. The chromophobe renal cell carcinoma cells grew in the initial phase (100%); however, in the second phase, we observed a chronic lymphomonocyte inflammatory reaction and a foreign body reaction. The CCRCC grew at 5–8 months both in the first and second phase (100%), maintaining the tumor type and grade.
Conclusions
The model with athymic Balb/c nude mice is useful for reproducing CCRCC, with the same histological characteristics and aggressiveness as native human tumors, promoting the development of the second experimental phase.
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To evaluate whether suppression of tumor microvasculature by double anti-angiogenic protein (DAAP) treatment could increase the extent of radiofrequency ablation (RFA)-induced coagulation in a murine renal cell carcinoma model.
Renal cell carcinoma cell lines were implanted subcutaneously into 10 nude mice. Four mice received adenoviral DAAP treatment and 6 mice received sterile 0.9% saline solution as DAAP-untreated group. The effect of DAAP was evaluated according to the vascularity by contrast-enhanced ultrasound (CEUS) using microbubbles. Four DAAP-treated mice and 4 DAAP-untreated mice were then treated with RFA, resulting in 3 groups: no-therapy (n = 2), RFA only (n = 4), and RFA combined with DAAP treatment (n = 4). Immediately after RFA, the size of coagulation necrosis and mitochondrial enzyme activity were compared between the groups using analysis of variance (ANOVA) and post hoc test.
The contrast enhancement ratio for tumor vascularization on CEUS was significantly lower in the DAAP treated group than in DAAP-untreated group (30.2 ± 9.9% vs. 77.4 ± 17.3%; p = 0.021). After RFA, the mean coagulation diameter was 0 mm for no-therapy group, 6.7 ± 0.7 mm for the RFA only group and 8.5 ± 0.4 mm for the RFA with DAAP group (ANOVA, p < 0.001). The area of viable mitochondria within the tumor was 27.9 ± 3.9% in no-therapy group, 10.3 ± 4.5% in the RFA only group, and 2.1 ± 0.7% in the RFA with DAAP group (ANOVA, p < 0.001).
Our results suggest the potential value of combining RFA with anti-angiogenic therapy.
After more than two decades of rising rates, in recent years the total kidney cancer incidence worldwide has shown signs of stabilizing, or even decreasing. In adults, kidney cancer consists of renal cell carcinoma (RCC), the predominant form, and renal transitional cell carcinoma (RTCC); these types primarily arise in the renal parenchyma and renal pelvis, respectively. Although temporal trends by kidney cancer type are not well established worldwide, incidence of RCC in the US has continued to rise, mainly for early-stage tumors, while that of RTCC has declined, and total kidney cancer mortality rates have leveled. Stabilization of kidney cancer mortality rates has also been reported in Europe. These trends are consistent with reports of increasing incidental diagnoses and a downward shift in tumor stage and size in clinical series. The changing prevalence of known risk factors for RCC, including cigarette smoking, obesity, and hypertension, is also likely to affect incidence trends, although their relative impact may differ between populations. Accumulating evidence suggests an etiologic role in RCC for physical activity, alcohol consumption, occupational exposure to trichloroethylene, and high parity among women, but further research is needed into the potential causal effects of these factors. Genetic factors and their interaction with environmental exposures are believed to influence risk of developing RCC, but a limited number of studies using candidate-gene approaches have not produced conclusive results. Large consortium efforts employing genome-wide scanning technology are underway, which hold promise for novel discoveries in renal carcinogenesis.
Both natural and synthetic estrogens are capable of inducing renal neoplasms in Syrian hamsters with an incidence approaching 100%. Neither the sequence of events nor the mechanisms involved in estrogen carcinogenesis in this model have been established. Results presented here indicate that estrogen induces renal tubular damage in the hamster kidney that is progressive and cumulative. Tubular injury was evident both as abnormal or lost microvilli, accumulation of cytoplasmic lipid droplets, vacuolization, and increases in secondary and tertiary lysosomes after 1.5 months of diethylstilbestrol (DES) treatment. Increasing tubular damage was evidence by the detachment of tubular cells, cell debris, and occluded renal tubular lumens. In an effort to repair proximal tubular damage in the hamster kidney elicited by estrogens, a 4.0-fold increase in proximal tubule BrdU labeling was evident at 4 months of DES or 17 beta-estradiol (E2) treatment and in earlier estrogen treatment periods (1-3 months). During this period, there was a significant increase in aneuploid cells in the hamster kidney, the near diploid frequency increased more than 6.0-fold, and the near tetraploid frequency increased at least 3.0-fold between 1.5 and 3.5 months of estrogen treatment. Based on these data, the early sequence of events leading to estrogen-induced renal neoplastic transformation in the hamster is presented.
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The mouse is an ideal model organism for human disease. Not only are mice physiologically similar to humans, but a large genetic reservoir of potential models of human disease has been generated through the identification of >1000 spontaneous, radiation- or chemically induced mutant loci. In addition, a number of recent technological advances have dramatically increased our ability to create mouse models of human disease. These technological advances include the development of highresolution genetic and physical linkage maps of the mouse genome, which in turn are facilitating the identification and cloning of mouse disease loci. Furthermore, transgenic technologies that allow one to ectopically express or make germ-line mutations in virtually any gene in the mouse genome have been developed, as well as methods for analyzing complex genetic diseases. In Part I of this review, we summarize some of the classical and modern approaches that have fueled the recent dramatic explosion in mouse disease model development. In Part II of this review, we list >100 mouse models of human disease where the homologous gene has been shown to be mutated in both human and mouse (Bedell et al., this issue). In the vast majority of these models, the mouse mutant phenotype very closely resembles the human disease phenotype and these models therefore provide valuable resources to understand how the diseases develop and to test ways to prevent or treat these diseases. Additionally, we highlight a number of areas of this research where significant progress has been made in the past few years.
Since sunitinib malate has shown activity in two uncontrolled studies in patients with metastatic renal-cell carcinoma, a comparison of the drug with interferon alfa in a phase 3 trial is warranted.
We enrolled 750 patients with previously untreated, metastatic renal-cell carcinoma in a multicenter, randomized, phase 3 trial to receive either repeated 6-week cycles of sunitinib (at a dose of 50 mg given orally once daily for 4 weeks, followed by 2 weeks without treatment) or interferon alfa (at a dose of 9 MU given subcutaneously three times weekly). The primary end point was progression-free survival. Secondary end points included the objective response rate, overall survival, patient-reported outcomes, and safety.
The median progression-free survival was significantly longer in the sunitinib group (11 months) than in the interferon alfa group (5 months), corresponding to a hazard ratio of 0.42 (95% confidence interval, 0.32 to 0.54; P<0.001). Sunitinib was also associated with a higher objective response rate than was interferon alfa (31% vs. 6%, P<0.001). The proportion of patients with grade 3 or 4 treatment-related fatigue was significantly higher in the group treated with interferon alfa, whereas diarrhea was more frequent in the sunitinib group (P<0.05). Patients in the sunitinib group reported a significantly better quality of life than did patients in the interferon alfa group (P<0.001).
Progression-free survival was longer and response rates were higher in patients with metastatic renal-cell cancer who received sunitinib than in those receiving interferon alfa (ClinicalTrials.gov numbers, NCT00098657 and NCT00083889 [ClinicalTrials.gov]).
The incidence of renal cell carcinoma is increasing, with up to one-third of patients presenting with metastatic disease. Combination therapy is used to prolong survival in patients with metastatic renal cell carcinoma, which carries a poor prognosis. Although two pivotal phase 3 trials have demonstrated the efficacy of immunotherapy after cytoreductive nephrectomy for metastatic disease, for now, targeted therapy has replaced immunotherapy as the preferred systemic treatment in these patients. Two ongoing phase 3 trials are evaluating the role of cytoreductive nephrectomy prior to targeted therapy. Proper patient selection is paramount in achieving successful outcomes. © 2016, Millennium Medical Publishing, Inc. All rights reserved.
The classification working group of the International Society of Urological Pathology consensus conference on renal neoplasia was in charge of making recommendations regarding additions and changes to the current World Health Organization Classification of Renal Tumors (2004). Members of the group performed an exhaustive literature review, assessed the results of the preconference survey and participated in the consensus conference discussion and polling activities. On the basis of the above inputs, there was consensus that 5 entities should be recognized as new distinct epithelial tumors within the classification system: tubulocystic renal cell carcinoma (RCC), acquired cystic disease-associated RCC, clear cell (tubulo) papillary RCC, the MiT family translocation RCCs (in particular t(6;11) RCC), and hereditary leiomyomatosis RCC syndrome-associated RCC. In addition, there are 3 rare carcinomas that were considered as emerging or provisional new entities: thyroid-like follicular RCC; succinate dehydrogenase B deficiency-associated RCC; and ALK translocation RCC. Further reports of these entities are required to better understand the nature and behavior of these highly unusual tumors. There were a number of new concepts and suggested modifications to the existing World Health Organization 2004 categories. Within the clear cell RCC group, it was agreed upon that multicystic clear cell RCC is best considered as a neoplasm of low malignant potential. There was agreement that subtyping of papillary RCC is of value and that the oncocytic variant of papillary RCC should not be considered as a distinct entity. The hybrid oncocytic chromophobe tumor, which is an indolent tumor that occurs in 3 settings, namely Birt-Hogg-Dubé Syndrome, renal oncocytosis, and as a sporadic neoplasm, was placed, for the time being, within the chromophobe RCC category. Recent advances related to collecting duct carcinoma, renal medullary carcinoma, and mucinous spindle cell and tubular RCC were elucidated. Outside of the epithelial category, advances in our understanding of angiomyolipoma, including the epithelioid and epithelial cystic variants, were considered. In addition, the apparent relationship between cystic nephroma and mixed epithelial and stromal tumor was discussed, with the consensus that these tumors form a spectrum of neoplasia. Finally, it was thought that the synovial sarcoma should be removed from the mixed epithelial and mesenchymal category and placed within the sarcoma group. The new classification is to be referred to as the International Society of Urological Pathology Vancouver Classification of Renal Neoplasia.
PurposeTo develop a reliable animal model able to reproduce the behavior of head and neck squamous cell carcinomas (HNSCC). This model should facilitate our understanding of the molecular mechanisms of tumorigenicity and progression of these tumors, as well as the evaluation of novel therapies.Material and methods20 nude mice nu/nu were injected intraorally and submucosally with a cell line derived from a human squamous cell carcinoma of the glottis.Results90% of the mice developed locally agressive squamous cell carcinomas, invading the surrounding muscle fibers and into loose connective tissue structures. All the tumors showed perineural growth. Four (22%) of the 18 mice showed bone destruction, and 22% vascular invasion. Tumor cells invaded lymphatic vessels in all the specimens, and 100% of the mice developed regional lymph node metastases. None of the animals developed haematogenous metastases.Conclusions
We present a metastasing model of HNSCC that resembles its human counterpart in many aspects.
In order to discriminate non-specific toxicity from the early precursor lesions of neoplasia, emphasis in these studies has been on the use of models requiring only a single administration of chemical. Our interests have focussed on three neoplastic entities in the kidney, renal mesenchymal neoplasia, renal cell carcinoma, and nephroblastoma. Dimethylnitrosamine administered as a single intraperitoneal injection to immature female Wistar rats, pre-conditioned for several days with a no-protein/sugar-only diet, has been used for investigating the complex morphological nature of renal mesenchymal tumors, their pathogenesis and the development of cell culture correlates. The near 100% tumor incidence and its facility for cell culture manipulation makes this a particularly potent model for studying chemical carcinogenesis and the evolution of cell transformation. Discovery that the rat kidney response to DMN was biphasic with respect to the time of treatment led to the subsequent development of a high incidence system for inducing renal adenocarcinoma, using older rats. Renal cell carcinomas could also be induced in mice by a single intravenous injection of streptozotocin. The tumor frequency in female CBA/H/T6J mice was almost 100%, providing a new model for the investigation of renal carcinogenesis in this species. Nephroblastoma has been a poorly comprehended neoplasm in both lower animals and man because of the lack of a high incidence model in conventional laboratory mammals. Recently, we have exploited an increased spontaneous predisposition of the Nb rat to nephroblastoma using a single intraperitoneal dose of N-ethylnitrosourea in pregnant females on day 18 of gestation, producing a frequency of 50% for this tumor type. More potent however, was a system which utilized the partially inbred IIIVO/J strain of rabbit using the same carcinogen and transplacental route of administration. The resultant incidence of nephroblastomas in the progeny was in excess of 90%, and like their counterparts in man, the neoplasms developed rapidly and had a potential for distant metastasis. Each one of these animal models is suitable for the sequential tracing of tumor pathogenesis, and in depth analysis of the biochemical and molecular mechanisms involved in the initiation and formation of different types of renal cancer.
In order to develop a high-frequency, single-dose model of renal epithelial tumor induction in the mouse, streptozotocin (250 mg/kg) was administered i.v. to 6-week-old males and females of the CBA/H/T6J strain. In groups of 26 males and 30 females representing the effective number of survivors eligible for tumor estimates, renal cell tumors were found in 73% of males and 97% of females, including incidences of lesions diagnosed as renal carcinoma in 31 and 60%, respectively. The difference in renal tumor frequency between the sexes was not considered a real effect owing to the significantly decreased survival of the males. The neoplastic lesions ranged from small papillary or cystopapillary adenomas with a benign appearance to large, solid carcinomas with a low potential for metastasis. In the females, 22% of the larger tumors metastasized to distant sites, mainly the lungs. Intermediate lesions incorporating both papillary and solid adenomatous profiles suggested a sequential development of carcinomas along this pathway from the smaller papillary foci. The data establish the administration of a single dose of streptozotocin in the female CBA/H/T6J as a suitable high incidence model for the study of renal epithelial carcinogenesis in the mouse.
The prognostic significance of morphologic parameters was evaluated in 103 patients with renal cell carcinoma diagnosed during 1961--1974. Pathologic material was classified as to pathologic stage, tumor size, cell arrangement, cell type and nuclear grade. Four nuclear grades (1--4) were defined in order of increasing nuclear size, irregularity and nucleolar prominence. Nuclear grade was more effective than each of the other parameters in predicting development of distant metastasis following nephrectomy. Among 45 patients who presented in Stage I, tumors classified as nuclear grade 1 did not metastasize for at least 5 years, whereas 50% of the higher grade tumors did so. Moreover, among Stage I tumors there was a significant difference in subsequent metastatic rate between nuclear grades 1 and 2. There was an apparent positive relationship between cell type and metastatic rate; clear cell tumors were less aggressive than predominantly granular cell tumors (metastatic rate 38% versus 71%). This relationship in part a function of the nuclear grade: only 5% of grade 3 and 4 tumors consisted of clear cells, whereas such high grades were seen in 57% of granular cell tumors. The size of the primary correlated well with the stage at the time of surgery. However, with the exception of extremely large and small tumors, the size was not useful in predicting the subsequent course of patients treated for Stage I tumors. Nuclear grade was the most significant prognostic criterion for the outcome of Stage I renal cell carcinoma.
This article is a bibliographic review concerning mouse mutations, spontaneous, induced or genetically engineered, as models of human genetic diseases. Since the beginning of the last century, mouse models have been instrumental in the understanding of the pathogenesis of many diseases and designing of new therapies. A number of recent technological advances in embryo manipulation and many large-scale mutagenesis screens will dramatically increase the availability of new mouse models in the near future. In the "post-genomic" era, mouse mutants will have a significant role as a model system for functional genome analysis of the upcoming whole-genome information of the human and mouse genomes projects.
To analyze to what extent histologic subtype is of prognostic importance in renal cell carcinoma based on a large, international, multicenter experience.
Four thousand sixty-three patients from eight international centers were included in this retrospective study. Histologic subtype (1997 International Union Against Cancer [UICC] criteria of tumor response), age, sex, TNM stage, Fuhrman grade, tumor size, Eastern Cooperative Oncology Goup performance status (ECOG PS), and overall survival were determined in all cases. The prognostic values of clear cell, papillary, and chromophobe histologic features were assessed by uni- and multivariate analysis using the Kaplan-Meier method and Cox model, respectively.
Clear cell, papillary, and chromophobe carcinomas accounted for 3,564 (87.7%), 396 (9.7%) and 103 (2.5%) cases, respectively. In univariate analysis, a trend toward a better survival was observed when clear cell, papillary, and chromophobe histologies were considered prognostic categories (log-rank P = .0007). However, in multivariate analysis, TNM stage, Fuhrman grade and ECOG PS, but not histology, were retained as independent prognostic variables (P < .001).
The stratification in three main renal cell carcinoma histologic subtypes as defined by the 1997 UICC-American Joint Committee on Cancer consensus should not be considered a major prognostic variable comparable to TNM stage, Fuhrman grade and ECOG PS.
To prospectively determine whether modulation of renal cell carcinoma (RCC) tumor microvasculature by using the antiangiogenic drug sorafenib could increase the extent of radiofrequency (RF)-induced coagulation in an RCC animal tumor model.
All investigations received animal care and utilization committee approval. RCC (human 786-0) was implanted subcutaneously into 27 nude mice. Sixteen mice were randomly assigned into one of three groups when tumors reached 12 mm in diameter: Six mice received 80 mg of sorafenib, a Raf kinase and vascular endothelial growth factor receptor inhibitor, per kilogram of body weight; five mice received 20 mg/kg sorafenib; and five mice received a control carrier vehicle alone. Antiangiogenic therapy was administered until a mean 1-mm reduction in tumor diameter was noted in one group. These 16 mice received a standard dose of RF ablation. Ablation size was visualized by using 2% triphenyltetrazolium chloride. An additional 11 tumors in mice treated with sorafenib alone were stained with CD31 to determine microvascular density (MVD). Resultant size of ablation was compared among groups; statistical significance was determined with analysis of variance. Differences in MVD were assessed with the Kruskal-Wallis test.
Over the 9-day administration of sorafenib, mean tumor size in the control group reached 15.2 mm +/- 0.8 (standard deviation). Tumors in mice receiving 20 mg/kg and 80 mg/kg sorafenib measured 12.2 mm +/- 0.6 and 11.1 mm +/- 0.5, respectively (P < .05). RF-induced coagulation diameter was 8.5 mm +/- 0.4 and 11.1 mm +/- 0.3 in the 20 mg/kg and 80 mg/kg sorafenib groups, respectively, but was only 6.7 mm +/- 0.7 for animals that underwent RF ablation alone (P < .01). Likewise, significant decreases in MVD were noted in the sorafenib-treated animals (P < .01).
Treatment of RCC in nude mice with the antiangiogenic agent sorafenib resulted in markedly decreased MVD and significantly larger zones of RF-induced coagulation necrosis.
Renal cell carcinoma presents several unique features, which distinguish it from other tumours. The increase in survival that has been described in patients with renal cell carcinoma following nephrectomy breaks a classical rule of oncology, which states that surgery of the primary tumour has no role in the treatment of patients with advanced disease. Together with melanoma, it is the only tumour in which immunomodulatory treatments with drugs such as interleukin-2 produces a clinical benefit to patients. In randomized trials treatment of metastatic renal cell carcinoma with high dose interleukin-2 has confirmed its ability to induce long-term complete responses, which in practice can be considered equivalent to cure. Lastly, renal cell carcinoma is being used as a clinical model to demonstrate the role of several targeted treatments, with over 30 novel agents under development. It has been the first tumour type in which treatment with angiogenesis inhibitors has shown a clinical benefit. This article reviews the most relevant aspects of renal cell carcinoma, including epidemiology, prognostic factors, clinical presentation, molecular bases and the current status of development of the most relevant novel treatments for this disease.