Metastasis of a human pancreatic adenocarcinoma (RWP-1) in nude mice

Chronologically-specific metastatic targeting of human pancreatic tumors in orthotopic models

Pancreatic cancer is a highly metastatic disease that responds poorly to currently-available treatment. In order to better visualize and understand the chronology and specificity of metastatic targeting of pancreatic cancer, two human pancreatic cancer cell lines, expressing green fluorescent protein (GFP), were studied in orthotopic models. MIA-PaCa2-GFP and BxPC-3-GFP tumor fragments were transplanted by surgical orthotopic implantation (SOI) to the nude mouse pancreas for fluorescence visualization of the chronology of pancreatic tumor growth and metastatic targeting. BxPC-3-GFP tumors developed rapidly in the pancreas and spread regionally to the spleen and retroperitoneum as early as six weeks. Distant metastases in BxPC-3-GFP were rare. In contrast, MIA-PaCa-2-GFP grew more slowly in the pancreas but rapidly metastasized to distant sites including liver and portal lymph nodes. Regional metastases in MIA-PaCa-2-GFP were rare. These studies demonstrate that pancreatic cancers have highly specific and individual 'seed-soil' interactions governing the chronology and sites of metastatic targeting.

Isolation and characterization of metastatic variants from human transitional cell carcinoma passaged by orthotopic implantation in athymic nude mice

PURPOSE

These studies were designed to develop an orthotopic model for human bladder cancer and to isolate variant metastatic cell lines.

MATERIALS AND METHODS

The human bladder cancer cell line 253J was implanted into the muscular wall of the bladder of athymic nude mice. By in vivo recycling, we selected for 2 variant cell lines: 253J B-V, a bladder line isolated after 5 serial passages in the bladder, and 253J lung-IV, established from a lung tumor nodule that was recycled through the bladder.

RESULTS

These 2 cell lines showed enhanced tumorigenicity, as measured by a decreased latent period, and rapid growth as compared with the parental cell line. Moreover, orthotopic implantation of these cell lines resulted in metastasis to the lungs. These in vivo-selected, metastatic cell lines exhibited unique karyotypic alterations, increased anchorage-independent growth, overexpression of basic fibroblast growth factor, altered expression of adhesion molecules and the ability to migrate through Matrigel.

CONCLUSIONS

This reproducible model of human bladder cancer offers the opportunity to study cellular properties associated with tumor progression and metastasis and is suitable for the evaluation of new therapeutic strategies for invasive bladder cancer.

Importance of orthotopic implantation for human tumors as model systems: relevance to metastasis and invasion

Transplantation of human tumors into immunodeficient athymic nude mice has become an important experimental approach to study the biology and the treatment of human cancer. Most human tumor xenograft experiments have employed subcutaneous injection procedures, but the main limit of this technique is the lack of metastasis from the subcutaneous site. The possibility of producing experimental metastasis by intravenous injection of cells in the animals has been known for a long time, and it has been recently reported that tumorigenic properties and metastatic ability of human cancer can be altered by transplantation of the tumor into its organ or tissue of origin in the recipient animals (orthotopic transplantation). In this paper we review (1) the principal techniques of orthotopic injection of most solid tumors, (2) the most recent techniques to achieve experimental metastases, and (3) the methods for preparing tumor cell suspensions from human surgical specimens suitable for transplantation into animals. These animal models should be used for a more appropriate evaluation of new antitumor treatments including the ones targeted to inhibit metastatic spread.

Characterization of the invasive and metastatic phenotype in human renal cell carcinoma

The purpose of these studies was to identify some characteristics of metastatic cells and deficiencies of non-metastatic cells in the heterogeneous SN12 human renal cell carcinoma. The SN12 parental line and several isolated variants with different metastatic potential were studied both in vivo and in vitro. We compared the ability of metastatic and non-metastatic cells to adhere to components of the extracellular matrix or to endothelial cells, to migrate and invade, to form multicell aggregates, to survive in the circulation, and to produce experimental and spontaneous lung metastases. In general, highly metastatic SN12 cells capable of producing spontaneous lung metastases demonstrated invasion through reconstituted basement membrane-coated filters; the cells also released diffusible collagenolytic activity into the culture medium that could enhance invasion by otherwise non-invasive and non-metastatic SN12 cells. In addition to enhanced invasion, metastatic cells produced more homotypic aggregation then non-metastatic cells and survived to produce experimental metastasis. Collectively, these data confirm that metastatic cells must complete all steps of the process; in this process, failure to produce metastasis is probably due to one or more deficiencies.

Orthotopic implantation of human colon carcinomas into nude mice provides a valuable model for the biology and therapy of metastasis

Human colon carcinomas (HCC) are heterogeneous for a variety of biological properties that include invasion and metastasis. The presence of a small subpopulation of cells with a highly metastatic phenotype has important clinical implications for diagnosis and therapy of cancer. For this reason, it is important to develop animal models for the selection and isolation of metastatic variants from human colon cancers and for testing the metastatic potential of these cells. We have implanted cells from more than 100 HCC (obtained from surgical specimens) into different organs of nude mice. Regardless of their malignant potential in the patient, the HCC did not metastasize unless they were implanted orthotopically. Only when they were injected into the cecum or spleen of nude mice did they yield hepatic metastases. These metastases consisted of highly metastatic cells. The invasive phenotype was influenced by the organ environment. HCC cells in the subcutis did not produce degradative enzymes and the cells did not metastasize. In contrast, HCC cells in the cecum did both. Collectively, the results demonstrate that the orthotopic implantation of HCC cells can yield metastatic subpopulations of cells suitable for the study of metastasis.

7th Jan Waldenström Lecture. The biology of human cancer metastasis

The process of cancer metastasis is dynamic and consists of sequential, interrelated steps. Malignant cells that produce metastases have survived a series of potentially lethal interactions that are regulated by both the intrinsic properties of the tumor cells and host factors. Although some of the steps in this process contain stochastic elements, metastases develop from the nonrandom survival of a few subpopulations of cells that preexist within the parent neoplasm. Metastases can have a clonal origin, and different metastases can originate from the proliferation of different cells. The orthotopic implantation of human cancer cells derived from surgical specimens into nude mice provides a biological model of metastasis. Using this model, clonal analysis of a human renal carcinoma, colon carcinoma, and melanoma has revealed that these tumors are heterogeneous for metastatic properties. Damage to an organ's environment is followed by inflammation and repair, and these homeostatic processes facilitate the proliferation of normal (physiology), and in some cases, tumor cells (pathology). Accelerated growth of human colon cancer cells was found in hepatectomized nude mice, whereas accelerated growth of human renal cancer cells was found in nephrectomized nude mice. These data suggest that systemic physiological signals can be usurped by neoplastic cells. Collectively, the factors that regulate metastasis are the intrinsic properties of metastatic cells and host factors involved in homeostasis.

Orthotopic implantation is essential for the selection, growth and metastasis of human renal cell cancer in nude mice [corrected]

Human neoplasms are heterogeneous for a variety of biological properties that include invasion and metastasis. The presence of a small subpopulation of cells with a highly metastatic phenotype has important clinical implications for diagnosis and therapy of cancer. For this reason, it is important to develop an animal model for the selection and isolation of metastatic variants from human neoplasms and for testing the metastatic potential of human tumor cells. We have implanted human renal cell carcinoma (HRCC) cells (obtained from a surgical specimen) into different organs of nude mice and then recovered the tumors and established each in culture. The 5 established lines differed in their biological-metastatic properties and had a unique karyotype, indicating that growth at different organs selects for different subpopulations of HRCC. Moreover, the HRCC did not metastasize unless they were implanted orthotopically. These findings indicate that the appropriate nude mouse model for studying the biology and therapy of HRCC must be based on the orthotopic implantation of tumor cells.

Variant sublines with different metastatic potentials selected in nude mice from human oral squamous cell carcinomas

Variant sublines LMF3, LMF4 and LMF5 with high metastatic potential were established from a human oral squamous carcinoma cell line HSC-3. These sublines metastasized to the draining lymph nodes after subcutaneous inoculation into nude mice. They were obtained by sequential selection in vivo from the parent HSC-3. At each step, the cells which metastasized to lymph nodes were cultured and reinoculated into nude mice. Two other cell lines HSC-2 and HSC-4 were also established from other patients, that had neither invasive nor metastatic potential. Biologic properties were compared among high metastatic, low metastatic and non-metastatic cells. Metastatic cells grew rapidly and invaded into surrounding tissues at the inoculated site. The incidence of pulmonary colonization after intravenous injection of tumor cells was high in selected variants. Metastatic cells formed diffuse colonies in type I collagen matrix and had a higher tendency to adhere to type IV collagen network.

A new animal model for human colon cancer metastasis

An animal model for human colon cancer metastasis is described in which spontaneously metastasizing colonic tumors are formed after injection of human colon cancer cells into the cecal wall of young athymic nude mice. Lymphatic and vascular invasion were demonstrated histologically after injection of both well- and poorly-differentiated cell lines, and metastases were found in a pattern similar to that of naturally occurring human colonic cancer. In contrast, little or no visceral organ involvement could be demonstrated after s.c. injection. Cells with increased liver-metastasizing potential were obtained by serial selection in this system. These cells had an enhanced ability to penetrate a reconstituted basement membrane in the presence of partially purified liver extract when compared to lung or brain extracts in a modified Boyden chamber assay. These results demonstrate the ability of human epithelial tumor cells to metastasize reproducibly in an animal model system, which may be useful for studying many aspects of the pathogenesis of cancer metastasis. In addition, it is suggested that local invasion by colon cancer cells may be influenced in part by tissue-specific factors.