Human gastric choriocarcinoma serially transplanted in nude mice

Molecular Biology of Pediatric and Adult Ovarian Germ Cell Tumors: A Review

Ovarian germ cell tumors (OGCTs) are rare in adults; indeed, they occur predominantly in children, adolescents, and young adults, and they account for approximately 11% of cancer diagnoses in these groups. Because OGCTs are rare tumors, our current understanding of them is sparse; this is because few studies have investigated the molecular basis of pediatric and adult cancers. Here, we review the etiopathogenesis of OGCTs in children and adults, and we address the molecular landscape of these tumors, including integrated genomic analysis, microRNAs, DNA methylation, the molecular implications of treatment resistance, and the development of in vitro and in vivo models. An elucidation of potential molecular alterations may provide a novel field for understanding the pathogenesis, tumorigenesis, diagnostic markers, and genetic peculiarity of the rarity and complexity of OGCTs.

Molecular Biology of Pediatric and Adult Male Germ Cell Tumors

Simple Summary

Although testicular germ cell tumors (TGCTs) are rare pediatric malignancies, they are the most common malignancies in young adult men. The similarities and differences between TGCTs in adults and children, taking into account the clinic presentation, biology, and molecular changes, are underexplored. In this paper, we aim to provide an overview of the molecular aspects of TGCTs, drawing a parallel between the findings in adult and pediatric groups.

Abstract

Cancer is a leading cause of death by disease in children and the second most prevalent of all causes in adults. Testicular germ cell tumors (TGCTs) make up 0.5% of pediatric malignancies, 14% of adolescent malignancies, and are the most common of malignancies in young adult men. Although the biology and clinical presentation of adult TGCTs share a significant overlap with those of the pediatric group, molecular evidence suggests that TGCTs in young children likely represent a distinct group compared to older adolescents and adults. The rarity of this cancer among pediatric ages is consistent with our current understanding, and few studies have analyzed and compared the molecular basis in childhood and adult cancers. Here, we review the major similarities and differences in cancer genetics, cytogenetics, epigenetics, and chemotherapy resistance between pediatric and adult TGCTs. Understanding the biological and molecular processes underlying TGCTs may help improve patient outcomes, and fuel further investigation and clinical research in childhood and adult TGCTs.

Ex Vivo Culture Models to Indicate Therapy Response in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is characterized by a poor 5 year survival and varying response rates to both standard-of-care and new treatments. Despite advances in medicine and treatment methods, mortality rates have hardly decreased in recent decades. Reliable patient-derived tumor models offer the chance to predict therapy response in a personalized setting, thereby improving treatment efficacy by identifying the most appropriate treatment regimen for each patient. Furthermore, ex vivo tumor models enable testing of novel therapies before introduction in clinical practice. A literature search was performed to identify relevant literature describing three-dimensional ex vivo culture models of HNSCC to examine sensitivity to chemotherapy, radiotherapy, immunotherapy and targeted therapy. We provide a comprehensive overview of the currently used three-dimensional ex vivo culture models for HNSCC with their advantages and limitations, including culture success percentage and comparison to the original tumor. Furthermore, we evaluate the potential of these models to predict patient therapy response.

Ex vivo tumor culture systems for functional drug testing and therapy response prediction

Optimal patient stratification is of utmost importance in the era of personalized medicine. Prediction of individual treatment responses by functional ex vivo assays requires model systems derived from viable tumor samples, which should closely resemble in vivo tumor characteristics and microenvironment. This review discusses a broad spectrum of model systems, ranging from classic 2D monolayer culture techniques to more experimental ‘cancer-on-chip’ procedures. We mainly focus on organotypic tumor slices that take tumor heterogeneity and tumor–stromal interactions into account. These 3D model systems can be exploited for patient selection as well as for fundamental research. Selection of the right model system for each specific research endeavor is crucial and requires careful balancing of the pros and cons of each technology.

Selection of the right therapy for individual cancer patients is very important with the expanding number of possible treatments. How tumors respond to a therapy can be tested by treating a sample from the tumor outside the body. Various culture methods can be used to maintain this tumor sample. Each of these model systems has its own benefits and disadvantages. In this review, we discuss the advantages and drawbacks of the available model systems and how they can be used to guide personalized medicine.

Heralding a new paradigm in 3D tumor modeling

Numerous studies to date have contributed to a paradigm shift in modeling cancer, moving from the traditional two-dimensional culture system to three-dimensional (3D) culture systems for cancer cell culture. This led to the inception of tumor engineering, which has undergone rapid advances over the years. In line with the recognition that tumors are not merely masses of proliferating cancer cells but rather, highly complex tissues consisting of a dynamic extracellular matrix together with stromal, immune and endothelial cells, significant efforts have been made to better recapitulate the tumor microenvironment in 3D. These approaches include the development of engineered matrices and co-cultures to replicate the complexity of tumor-stroma interactions in vitro. However, the tumor engineering and cancer biology fields have traditionally relied heavily on the use of cancer cell lines as a cell source in tumor modeling. While cancer cell lines have contributed to a wealth of knowledge in cancer biology, the use of this cell source is increasingly perceived as a major contributing factor to the dismal failure rate of oncology drugs in drug development. Backing this notion is the increasing evidence that tumors possess intrinsic heterogeneity, which predominantly homogeneous cancer cell lines poorly reflect. Tumor heterogeneity contributes to therapeutic resistance in patients. To overcome this limitation, cancer cell lines are beginning to be replaced by primary tumor cell sources, in the form of patient-derived xenografts and organoids cultures. Moving forward, we propose that further advances in tumor engineering would require that tumor heterogeneity (tumor variants) be taken into consideration together with tumor complexity (tumor-stroma interactions). In this review, we provide a comprehensive overview of what has been achieved in recapitulating tumor complexity, and discuss the importance of incorporating tumor heterogeneity into 3D in vitro tumor models. This work carves out the roadmap for 3D tumor engineering and highlights some of the challenges that need to be addressed as we move forward into the next chapter.

The future of patient-derived tumor xenografts in cancer treatment

Over the last decades, major technological advancements have led to a better understanding of the molecular drivers of human malignancies. Nonetheless, this progress only marginally impacted the cancer therapeutic approach, probably due to the limited ability of experimental models to predict efficacy in clinical trials. In an effort to offset this limitation, there has been an increasing interest in the development of patient-derived xenograft (PDX) models where human tumors are xenotransplanted into immunocompromised mice. Considering their high resemblance to human tumors and their stability, PDX models are becoming the preferred translational tools in preclinical studies. Nonetheless, several limitations hamper a wider use of PDX models and tarnish the concept that they might represent the missing piece in the personalized medicine puzzle.

Mouse models of metastatic pancreatic adenocarcinoma

Pancreatic adenocarcinoma is a deadly disease. Its etiology is unknown, and metastatic disease kills the majority of patients who have it. Effective prevention is clearly the ultimate goal for eradicating this disease provided that the effects of environmental and genetic elements on pancreatic cancer development are fully understood. Currently, it appears that the control of pancreatic cancer metastasis is of immediate urgency. Fulfillment of this difficult task relies on knowledge of the cellular and molecular biology of metastasis. The use of relevant animal models will help define each aspect of this complicated process.

Metastatic phenotype correlates with high expression of membrane-associated complete beta-human chorionic gonadotropin in vivo

BACKGROUND

Investigations using living human cancer cells and the nude mouse model were conducted to evaluate the expression of human chorionic gonadotropin (hCG) in various cancers grown in vitro and in vivo. The aim was to determine whether membrane-associated hCG in any of its forms is a characteristic metastatic marker, and at what levels or ratios.

METHODS

Human cancer cell lines known to produce tumors that metastasize spontaneously when grown in nude mice (n = 4) were compared with those that do not produce such tumors (n = 4) using analytical (quantitative) flow cytometry. Monoclonal antibodies directed to epitopes of intact hCG (hCG-holo) and its subunits, including beta-human chorionic gonadotropin with its carboxy-terminal peptide (hCG beta-CTP), allowed for the determination of hCG beta-CTP/hCG-holo ratios.

RESULTS

No significant difference in hCG beta-CTP/hCG-holo ratios was found between the cultured human cancer cells that do not metastasize spontaneously (ratio = 2.39) and those that do (ratio = 2.13), and no difference was seen in their growth rate in nude mice. However, the cells isolated from tumors that do not metastasize spontaneously showed a decrease in their ratios to values less than 1. They reverted to their original values after reestablishment in culture and subsequent passages. In contrast, the ratios shown by cells isolated from tumors that metastasize spontaneously increased to 3 to 6 times their original values in culture, then reverted to their original values after reestablishment in culture and subsequent passages.

CONCLUSIONS

To our knowledge, these data demonstrate the following for the first time: 1) There is a direct in vivo correlation between human cancer cells that metastasize spontaneously in nude mice and the expression of membrane-associated complete hCG beta (hCG beta-CTP); and the correlation identifies this molecule as a characteristic metastatic phenotype marker. 2) The marked ratio variations under different conditions indicate that the metastatic phenotype is an unstable event. 3) Growth and local invasion in vivo correlates with the expression of hCG-holo.

Distribution of beta-human chorionic gonadotropin-positive cells in noncancerous gastric mucosa and in malignant gastric tumors

The authors examined the localization and behavior of beta-human chorionic gonadotropin (HCG)-positive cells in human gastric noncancerous mucosa and in gastric malignant tumors, using immunohistochemistry and the anti-beta-HCG antibody. The beta-HCG-positive cells were located mainly in the antral mucosa and were generally restricted to the neck portion of the pyloric glands, although a few were present in fundic glands of the gastric body. The beta-HCG-immunoreactive cells were found in gastric carcinomas in 53% of the 92 cases examined. These cells were observed more often in advanced carcinomas that were histologically poorly differentiated than in early carcinomas or in well-differentiated tumors, but this prevalence had no statistical significance. The presence of the beta-HCG-positive cells in the gastric carcinomas suggested no appreciable prognostic significance, even quantitatively. In the syncytiotrophoblast-like tumor cells seen in four gastric tumor samples with histologic features of a choriocarcinoma, immunoreactivity to the beta-HCG was striking. There was, however, no recognizable dominance in the number of beta-HCG-reactive cells in the noncancerous mucosa around the tumor.

Rationale and methods for the use of nude mice to study the biology and therapy of human cancer metastasis

Human neoplasms are biologically heterogeneous. The extensive cellular diversity found in malignant neoplasms is generated by the rapid emergence of clonal subpopulations of tumor cells with different properties that include invasion, metastasis and responsiveness to treatment. Studies in rodent systems have indicated that cancer metastases can be clonal in their origin and that different metastases can originate from different progenitor cells from the primary tumor. This metastatic heterogeneity of tumor cells has many ramifications for studies of tumor biology, in general, and studies of therapy, in particular. The heterogeneous nature of metastatic human neoplasms can now be studied under defined conditions in healthy athymic nude mice. The neoplasms must be free of mouse pathogens and the mice must be kept in specific-pathogen-free conditions. Careful consideration must be given to the intimate tumor-host relationship for each tumor system studied, because the metastatic potential of human neoplasms can vary with the site of implantation into nude mice. Several methods for studying the biology of human neoplasms in the nude mouse are described as well as techniques to assure the success of these studies. The data show that the healthy young nude mouse can be a useful in vivo model for ascertaining the metastatic potential of human neoplasms, for selecting and maintaining cell variants of high metastatic potential from heterogeneous human tumors, and for studying therapeutic agents directed against metastatic cells proliferating in visceral organs.

Predictive testing in cancer chemotherapy. I. In vivo

Several in vivo methods have been assessed for their capacity to predict sensitivity for anticancer agents in humans. Standard strategies have been developed for screening purposes. Adjustments of these strategies are frequently suggested in reports in which the correlation between assay results and clinical therapeutic efficacy is analysed. Low predictivity and high costs of these assays are important reasons for changing the screening strategy. In vivo methods which predict the clinical response in the individual patient, are under investigation. Only the results of the subrenal capsule assay (in normal mice) have been correlated with the clinical response in a larger study. The criticism of the method and the low predictivity for sensitivity in a prospective study provide no reason for optimism. Methods which study changes predicting the clinical response in patients are still in a developmental phase.

An investigation of cellular components released from human renal cancer and foetal kidney xenografts in nude mice (nu/nu) by cross-immunization of hairy littermate relatives

The release of components from human kidney tumour xenografts (GYL) and human foetal kidney explants maintained in nude mice has been studied. The GYL tumour released antigens into the serum which could be detected by the generation of antibodies following cross-immunisation of closely related hairy litter mate (HLM) mice. The production of anti-GYL antibody was monitored by an I125 binding assay using viable GYL tumour cells. In 2/16 hairy litter mate mice, cell surface antibody binding by GYL cells was twice that found with 8 other human tumour cell lines (including 2 other kidney cancer cell lines). Absorption of these antisera with 10(7) GYL tumour cells completely abolished this response, where 50%, 38% and 25% of activity remained following absorption with; a normal kidney cell line, a homogenate of normal kidney and a mixed pool of human tumour cells. Six out of 8 GYL tumour bearing nude mice tested had elevated plasma levels of HCG. Absorption of the HLM antisera with an excess of commercial HCG abrogated I125 binding by only 15%, suggesting that antibody production was not directed primarily against ectopic HCG.

Choriocarcinomatous change with immunocytochemically HCG-positive cells in the gastric carcinoma of the males

Gastric choriocarcinoma is a rare tumor and attracts interest because of its controversial pathogenesis. The present study reports a choriocarcinomatous change with immunocytochemically hCG-positive cells in the gastric carcinoma. The patients were males, one was 41 years old and the other 42 years old. The tumor of both cases consists of adenocarcinoma and choriocarcinoma. A sequential process of morphological transition of the adenocarcinoma to the choriocarcinoma can be traced. Indirect immunoperoxidase stain (PAP method) for human chorionic gonadotropin (hCG) demonstrates the localization of hCG in the syncytiotrophoblasts. Small number of cytotrophoblasts are weakly positive. None of the components of adenocarcinoma of both cases is positive for hCG. Human placental lactogen is not demonstrated in both cases. Stain for pregnancy specific beta-1 glycoprotein is weakly positive in the adenocarcinoma of one case but not in the choriocarcinoma. In one case, the concentration of hCG was 19.9 mIU/ml in the preoperative serum and decreased to 1.2 mIU/ml after gastrectomy. HCG production by gastric carcinoma was discussed with regard to possible pathogenesis of gastric choriocarcinoma.

Production of alpha-fetoprotein, normal serum proteins, and human chorionic gonadotropin in stomach cancer: histologic and immunohistochemical analyses of 35 cases

By immunoperoxidase histochemical staining of formalin-fixed paraffin-embedded sections, the production of alpha-fetoprotein(AFP), albumin(ALB), transferrin(TF), alpha-1-antitrypsin(AAT), and human chorionic gonadotropin(HCG) was examined in 35 operatively resected stomach cancers with elevated serum AFP levels (higher than 20 ng/ml as determined by radioimmunoassay). Cells positive for AFP were found in 19 cases (54%). In 29 cases (83%), some tumor cells contained normal serum proteins (ALB, TF, or AAT). All 19 tumors with AFP-positive cells also stained positively for two or three kinds of normal serum proteins. In some cases, AFP and normal serum proteins were localized in the same cells. There were two cases in which metastatic tumors produced AFP, whereas the primary sites did not. In nine cases (26%), HCG was present in tumor cells and HCG- and AFP-positive cells were coexistent in six tumors. Histologic examination of AFP-producing stomach tumors revealed medullary or papillotubular arrangements with marked nuclear atypia and eosinophilic granular or clear cytoplasms containing no glycogen or mucin. Some tumors with medullary patterns resembled liver cell carcinomas. Concordant phenotypic expression of AFP and normal serum protein production appears to be a general feature of AFP-producing tumors such as liver cell carcinoma, yolk sac tumor, and stomach cancer.

A human choriocarcinoma xenograft in nude mice; a model for the study of antibody localization

The successful development of the concept of linking cell-killing agents to tumour-specific antibodies will be largely determined by the extent to which the antibodies are preferentially localized in the malignant tissue. A xenograft of human choriocarcinoma (CC3) has been established in nude mice, and the relative distribution of affinity-purified specific antibodies to human chorionic gonadotrophin has been compared with that of nonspecific antibodies from the same species. Treatment of the nonspecific antibodies with ammonium thiocyanate appeared to be important to ensure that the distributions in normal nude mice were equivalent. Specificity indices, derived from the comparative distributions of isotope activity in the tumour and lung of labelled specific and nonspecific antibodies, ranged between 1.3 and 2.0.

Adenocarcinoma of the colon with choriocarcinoma in its metastases

A 49-year-old woman died from metastases from a colon carcinoma. This was predominantly an ordinary tubular adenocarcinoma but it included arease of much less differentiated appearance with giant cells, while the hepatic and pulmonary metastase were poorly differentiated and contained choriocarcinoma, as established by means of morphologic and immunocytochemical examination. The choriocarcinoma appeared to be due to metaplasia within the carcinomatous tissue. This and other similar cases of mixed tumours suggest that unexpected trophoblastic differentiation may result from aberrant differentiation of locally proliferating cells, rather than originating in ectopic germ cells or in foci of embryonic totipotent cells. Implications for possible origin and for classification of tumors are briefly discussed.

Influence of the mouse hepatitis virus (MHV) infection on the growth of human tumors in the athymic mouse

The growth characteristics and histological appearance of tumors resulting from transplantation of the tumor lines HEp-2 and SW480 into pathogen-free and mouse hepatitis virus infected athymic mice were studied. Subcutaneous or intraperitoneal implantation 1 x 10(6) neoplastic cells into pathogen-free animals resulted in tumor growth. Subcutaneous transplants grew locally, surrounded by a capsule of connective tissue. The fibrovascular stroma supporting the neoplastic tissue was minimal and infiltration of tumor capsule was observed. Intraperitoneal tumors grew in a multifocal pattern, were not encapsulated, showed marked invasiveness and metastasized. The same number of neoplastic cells (1 x 10(6)) transplanted into hepatitis-positive animals failed to develop into grossly visible tumors. When the number of transplanted cells was increased to 2 x 10(7), tumors appeared in a few animals. All tumors, regardless of the site of transplantation, were characterized by the presence of severe fibrohistiocytic reaction at the site of implantation that possibily influenced the tumor growth. No evidence supporting T-cell-mediated tumor rejection was observed. It is concluded that the state of health of the athymic mice is critical for the growth of human tumors and may account for the variations in reporting successful transplantation of such tumors in nude mice.

Human neuroblastoma serially transplanted in nude mice and metastases

A human neuroblastoma from a female patient was directly transplanted into nude mice and serial transplantation was established. Histology of the transplanted tumor was almost the same as that of the patient. During serial transplantation, a high frequency of metastasis to distant organs such as ovaries, lymph node and cerebrum was observed, especially in the ovaries where the metastatic rate reached to 66%. Regarding the distribution of organs involved, there is close similarity between that in the patient with neuroblastoma and tumor-bearing mice. This transplantable human neuroblastoma provided a unique research tool for studies on its morphological and biological nature, including metastasis.

Chemotherapy of human choriocarcinoma transplanted to nude mice

Two human choriocarcinomas serially transplanted to athymic nude mice (BALB/c, nu/nu) were treated with intraperitoneal injections of methotrexate (MTX), actinomycin D (ACTD), and vinblastine (VLB) with doses per injection slightly smaller than LD10 in mice. Both ACTD and VLB significantly suppressed the growth of one tumor strain (SCH) but MTX did not. The growth of another tumor strain (CC-1) was not inhibited by either ACTD or VLB. In strain SCH, plasma HCG of tumor-bearing animals increased approximately in parallel with the growth of tumors in control and MTX-, ACTD-, and VLB-treated groups but the suppression of the hormone release was more marked in the ACTD-treated group. The results indicate that these two transplantable human tumors are useful models for the study of choriocarcinoma, particularly for therapeutic experiments.

Growth of human tumors in lethally irradiated mice reconstituted with syngeneic fetal liver cells

Transplantation into lethally irradiated mice of hematopoietic and lymphoid cells from immature donors which hypothetically will not mount a cell mediated attack against simultaneously inoculated human tumor cells has resulted in tumor engraftment and growth in long-term surviving radiation chimeras. Twenty-four hours after lethal irradiation, A or CBA mice were given iv injections of 2 X 10(7) fetal liver cells from syngeneic donors of 14, 16, or 18 days of embryonation and sc injections of 1, 3, or 6 X 10(6) human choriocarcinoma (C-1, C-2, and C-3) cells or human breast carcinoma (B-1) cells that had been maintained in culture. Palpable tumors greater than or equal to 5 mm were noted in 18/22 mice injected with C-1, 9/16 with C-2, 10/10 with C-3, and 18/30 with B-1. Tumors of 17 (31%) of mice remained palpable until death of the animal or until termination of the experiment 100 days post inoculation. Histologic study of autopsy specimens revealed malignant tumors with occasional pulmonary metastases. Human chorionic gonadotropin was found in the serum of mice that received choriocarcinoma cells.