Heterotransplantation of human craniopharyngiomas in athymic "nude" mice.

Surgical biopsies from 2 human craniopharyngiomas were transplanted subcutaneously into 6 athymic "nude" mice. Morphologically characteristic craniopharyngiomas grew in 5 of these animals. In 4 animals growth was sufficient to allow transplantation into a second generation of animals. In all, 11 craniopharyngiomas were present at autopsy in the 14 animals into which the tumors had been transplanted. The tumors that grew in the animals had the same adamantinomatous architecture, epithelial nests, and keratinized nodules that were present in the original surgical sample and that are characteristic of human craniopharyngiomas. It may be possible to study growth characteristics and therapeutic sensitivities of human craniopharygniomas growing in "nude" mice.     

Ultraviolet carcinogenesis in athymic nude mice

We have investigated the development of skin cancer from exposure to ultraviolet (UV) radiation in C3H- nu/nu nude mice. Nude mice, nude mice reconstituted with thymuses, and nude mouse skin grafted onto normal haired mice had similar tumor incidences and rates of tumor development. All tumors were squamous cell carcinomas and both well-differentiated and poorly differentiated lesions occurred in each of the groups. Transplants of the tumors that developed in nude skin grew preferentially in immunosuppressed mice as compared with normal mice, indicating that tumors from each treatment group were antigenic. These results indicate that the presence or absence of a functioning thymus does not seem to influence UV carcinogenesis.     

Patterns of metastasis by the human prostate cancer cell line PC-3 in athymic nude mice

Cells from the PC-3 human prostate cancer cell line were evaluated in athymic nude mice in order to determine the influence of size of the primary tumor and site inoculation on the incidence and pattern of metastasis. At autopsy, all organs, including the skeleton, were evaluated for metastasis. Subcutaneous injections resulted in metastases to the draining axillary lymph node and lungs (56% and 13%, respectively), and were correlated with size of the primary tumor. Tail vein injection resulted in a high incidence of lung metastasis, while injection into the peritoneal space, spleen, and seminal vesicles resulted in intraabdominal tumor growth, liver metastasis, and large tumors within the seminal vesicles, respectively. Skeletal metastases were not observed in any of the animals studied. We conclude that injection of PC-3 cells into various sites results in different patterns of metastasis, but may not constitute an entirely suitable animal model of human prostate cancer due to the lack of metastasis to the skeleton.     

Growth of osteoid osteoma transplanted into athymic nude mice.

An osteoid osteoma, excised from the neck of the femur of a 23-year-old man, was cut into four 1.5 mm3 fragments and immediately transplanted into muscle pouches in athymic nude mice. One fragment was devitalized by lyophilization before implantation. The viable tumor cell xenografts grew, differentiated into uncalcified osteoid, and retained the characteristics of the original tumor. The killed implants were resorbed, but both the surviving viable and nonviable tumor tissue induced the connective tissue cells of the mouse host bed to proliferate and differentiate into normal cartilage and calcified bone. The mouse new bone deposits were remodeled and colonized by bone marrow, a tissue not seen in osteoid osteomas. These observations suggest that the sclerotic bone shell characteristic of osteoid osteomas may be an inductive reaction of host bed tissue to an osteoma cell product that is comparable to bone morphogenetic protein (BMP) produced by normal bone cells and transferred by normal bone matrix.     

Interferon-inhibited human osteosarcoma xenografts induce host bone in nude mice

The growth of human osteosarcoma xenografts in nude mice can be inhibited by human interferon-alpha (IFN-alpha). Histologic examination of growth-inhibited tumors has revealed mineralization and partial replacement of the tumor by normal bone tissue. We have investigated whether the normal bone tissue was formed by differentiated tumor cells or by induction of host stroma to differentiate into bone tissue. Employing antibodies to both murine and human type I collagen, it was found that the normal bone produced in IFN-inhibited osteosarcomas was host derived. These results suggest that IFN induced the osteosarcoma cells to produce a bone-inductive agent that interacts with the host cells, and leads to the formation of mature normal bone tissue in a heterotopic site.     

Preclinical chemotherapy on human head and neck cancer xenografts grown in athymic nude mice

This study was undertaken to investigate the potential role of xenografts established from human head and neck squamous cell carcinoma (HNSCC) in the selection of new anticancer agents for phase II clinical trials. Eight HNSCC tumor lines were established in NMRI nude mice. The tumor-bearing animals were then treated with drugs at the maximum tolerated dose level. Treatment with drugs known for their activity in 15%-30% of HNSCC patients [cisplatin (CDDP), bleomycin (BLEO), 5-fluorouracil (5-Fu), cyclophosphamide (CY), and doxorubicin (DOX)] caused strong responses in up to 38% and moderate responses in 50%-67% of the HNSCC tumor lines. Methotrexate (MTX), known to cause remissions in about 40% of HNSCC patients, was only minimally active in this model system. A clinically ineffective drug, amsacrine (m-AMSA), was included as a negative control and showed no or minimal activity in all four HNSCC lines tested. A number of experimental drugs that have promising preclinical activity were also tested. Brequinar sodium (Dup 785) and 10-ethyl, 10-deaza-aminopterin (10-EdAM) showed activity in three of five, and two of the four tested tumor lines respectively. N,N-dimethylformamide (DMF) and 5-aza-2'-deoxycytidine (5-aza-dCyd), agents with the capacity to induce differentiation in in vitro systems, showed moderate activity in 43% and 40%, and strong activity in 14% and 40% of the lines, respectively. Our results indicate that the nude mouse xenograft model may play a role in the screening of new drugs, and in particular, it could be of help in the selection of drugs to be tested in phase II HNSCC clinical trials.     

Metastatic properties of the human prostatic cell line, PPC-1, in athymic nude mice

Limitation in the number of human prostatic cell lines has created a gap in knowledge regarding the in-vivo progression of this common cancer. The recently isolated primary prostatic carcinoma cell line, PPC-1, has been shown to be tumorigenic in athymic nude mice. These cells are now shown to form metastases to secondary sites in 10 of 12 animals in this initial study. Metastases were localized to lung and lymph nodes, and the tumor histology closely resembled that of the undifferentiated, rapidly dividing primary tumors. This is the first report describing the metastatic properties of a primary prostatic cancer cell line. PPC-1 cells are therefore likely to represent a good model system for the study of human prostate cancer progression.     

Osteogenic capacity of rat and human marrow cells in porous ceramics. Experiments in athymic (nude) mice

Porous hydroxyapatite ceramics, alone and combined with rat marrow cells, were implanted subcutaneously in 22 nude mice. The ceramics alone were invaded by fibrovascular tissue without any bone formation. In contrast, all the ceramics combined with marrow cells had bone formation in the pores 4 to 8 weeks after implantation. The bone formation began on the surface of the ceramic with direct bonding of the bone to the ceramic and proceeded to the center of the pores. The ceramics were also combined with bone marrow cells from 7 humans and implanted in nude mice. In five experiments, bone formation occurred after implantation. In addition, the ceramics were combined with in vitro cultured fibroblastic cells, resulting in bone formation in 2/6 cases. Our results indicate that the osteogenic ability of human marrow cells is sustained by porous hydroxyapatite ceramics.     

Transplantable human prostatic carcinoma (PC-82) in athymic nude mice. II. Tumor growth and androgen receptors

Androgen receptor (AR) levels were measured in PC-82 tumor tissue grown in hormonally manipulated nude mice. In the nuclei of tumor tissue from intact male mice a relatively low concentration (mean 25 fmol/mg protein) of androgen receptors (ARn) was found, while no receptors for estrogens or progestins were detected. The total number of androgen receptors in the PC-82 tumor tissue (measured in the nuclei 1 h after injection of a single high dose of testosterone (T)) was found to be 100 fmol/mg protein. The antiandrogen cyproterone acetate, administered in combination with the high dose of T, significantly lowered the amount of ARn in the tumor tissue. In the nuclei of tumor tissue from intact tumor-bearing male mice with T-containing Silastic implants, a 4-times higher amount of tightly associated AR was found. In addition, an increased growth rate of the tumor was observed following T implantation. This finding suggests that the increased growth rate of the PC-82 tumor is associated with a continuous occupancy of AR in the nuclei of the tumor tissue. Castration of tumor-bearing male mice, which arrests the growth of this tumor, did not affect the concentration of ARn in the tissue compared to that of tissue in the intact control situation. In addition, the total amount of AR measured after T injection was not affected by castration. Therefore, the availability of a sufficient and steady level of T in the plasma and consequently the duration of the presence of AR in the nucleus of the PC-82 tumor tissue, rather than the total concentration of AR, appear to be the limiting factors in the modulation of hormonal responses in this androgen target tissue.     

Heterotransplantation of human transitional cell carcinoma in athymic mice.

Human bladder tumors were obtained and transplanted into nude mice or other control animals. Tumor measurements, growth rate and selected histological studies were completed. No correlation between the growth of the tumor in the nude mouse and the clinical course of histologic tumor appearance in the host was detected. Metastases were not found. This feature has been noted generally to be uncommon in the nude mice model with some other human tumors. Despite careful technique tumor growth was achieved in only 40% of the appropriate experiments. The factors responsible for this variability and different growth rate in the nude mouse require further assessment before the results of other experimental treatments can be evaluated.     

Transplantable human prostatic carcinoma (PC-82) in athymic nude mice. III. Effects of estrogens on the growth of the tumor tissue

The transplantable human prostatic tumor model (PC-82) in nude mice was used to evaluate the indirect and possibly direct effects of estrogens on the growth of prostatic tumor tissue. High (pharmalogical) doses of plasma estradiol (E2) were achieved in tumor-bearing mice by using E2-containing Silastic implants of different lengths. In comparison with the situation in men, in mice much higher concentrations of circulating E2 (exceeding 3 nmol/liter) were necessary to attain (near)-castrate levels of plasma testosterone (T). Treatment of tumor-bearing mice with a high dose of E2 resulted in tumor growth arrest and a subsequent decline of the tumor volume, which equals the effects of castration. No evidence was found that either of the two doses of E2 applied had any additive inhibitory effect on tumor growth when compared to castration alone. It was inferred from these findings that in the PC-82 tumor model, estrogens, rather than having a direct effect on the tumor tissue, mainly act indirectly by their suppressive effect on T secretion in the host animal. A different and unexpected result was obtained in castrated tumor-bearing mice treated with a combination of E2 and T. With both doses of E2 this type of treatment led to a smaller increase of the tumor volume compared with mice receiving T only, the result of the high dose being statistically significant. This antagonistic effect of the two steroids on the PC-82 tissue was paradoxically associated with a sharp increase of nuclear androgen receptor levels and a higher concentration of dihydrotestosterone in the tumor tissue. Plasma and tissue concentrations of T appeared to be unaltered. The present study of the PC-82 prostate tumor shows that only by careful monitoring of plasma steroid levels in tumor-bearing mice can conclusions about the effectiveness of hormonal treatment regimens, such as estrogen therapy, be drawn.     

Metastatic potential of human renal cell carcinoma: experimental model using subrenal capsule implantation in athymic nude mice

Summary The aim of this study was to determine whether subrenal capsule (SRC) implantation is a suitable model for the study of the metastatic potential of our human renal cell carcinoma (HRCC) lines and to establish new sublines with enhanced metastatic ability. NMRI athymic nude mice 7–11 weeks old received SRC implantation of our HRCC lines RC43 and RC21. These lines were not metastatic when implanted s.c. Mice were killed after 4 or 8 weeks, or when moribund. With the RC43 cell line the success rate for implantation was 69%, with 89% of these showing metastases. The average volume of the implanted tumour fragments was 0.5 mm³ (range 0.28–0.7), the average volume at the primary site at the time of death was 9087 (9–32000) mm³. Metastases were found in lymph nodes, liver, spleen, peritoneum, psoas muscle, pancreas, diaphragm and skin. The average volume of the metastases was 4139 (0.5–9000) mm³. Growing cell lines were established in vivo and in vitro from one splenic, one peritoneal, one diaphragmatic, and one hepatic metastasis. These sublines have faster in vivo and slower in vitro growth rates than the parental lines. With the RC21 cell line the success rate for implantation was 56% and the metastatic rate 78%. The average volume of the implanted tumour was 0.8 mm³ (0.28–1.2), the average volume at the primary site at the time of death was 2685 mm³ (1.4–6534) and the average volume of metastases was 7.1 mm³ (0.5–37.5). Metastases were found in lymph nodes, lung and skin. No establishment was attempted for RC21 because of the small dimensions of these metastases. SRC implantation is thus considered a useful tool for the study of the metastatic ability of our cell lines RC43 and RC21. The establishment of new sublines with a faster growth rate and an enhanced metastatic ability will be useful for further studies on the metastatic process.     

Osteogenic capacity of rat and human marrow cells in porous ceramics: Experiments in athymic (nude) mice

Porous hydroxyapatite ceramics, alone and combined with rat marrow cells, were implanted subcutaneously in 22 nude mice. The ceramics alone were invaded by fibrovascular tissue without any bone formation. In contrast, all the ceramics combined with marrow cells had bone formation in the pores 4 to 8 weeks after implantation. The bone formation began on the surface of the ceramic with direct bonding of the bone to the ceramic and proceeded to the center of the pores.

The ceramics were also combined with bone marrow cells from 7 humans and implanted in nude mice. In five experiments, bone formation occurred after implantation. In addition, the ceramics were combined with in vitro cultured fibroblastic cells, resulting in bone formation in 2/6 cases. Our results indicate that the osteogenic ability of human marrow cells is sustained by porous hydroxyapatite ceramics.     

Localizing and photosensitizing mechanism by tetra(3-hydroxyphenyl)porphin in vivo on human malignant melanoma xenografts in athymic nude mice

Observations on time-dependent localization of tetra(3-hydroxyphenyl)porphin (3-THPP) in human malignant melanoma transplanted to athymic nude mice from 1 to 120 h after intraperitoneal (i.p.) 10 mg kg^–1 b.w. administration were made by means of fluorescence microscopy. Fluorescence was found on the membrane of the melanoma cells and in the cytoplasm with a peak fluorescence intensity at 24 h post-injection of 3-THPP. The growth of the tumour cells was obviously inhibited at an early stage after PCT. Morphological changes of the tumour at various intervals after treatment by PCT with 3-THPP were also observed. Diffuse degeneration of the tumour cells with swelling of mitochondria and endoplasmic reticulum, heterochromatin aggregation and margination, etc., and subsequently diffuse necrosis with little or no the background of tumorous vascular response were found at an early stage after PCT. On the other hand, it was also observed that the necrosis of the melanoma areas was caused as a consequence of tumorous vascular injury at a later stage after PCT. Thus, two tumoricidal processes caused by PCT with 3-THPP were seen: a direct phototoxic action on tumour cells at an early stage after PCT and an indirect effect secondary to tumorous vascular injury at a later period after PCT.     

Spontaneous hyperglycemia and impaired glucose tolerance in athymic nude BALB/c mice

Basal plasma glucose, glucose tolerance, and insulin secretion were investigated in young and mature athymic nude BALB/c mice and in age-matched controls. Basal plasma glucose levels in male athymic nude mice were similar to those of controls at 1, 3, and 4 wk of age. At 6, 8, and 12 wk of age, male athymic nudes had significantly higher basal plasma glucose levels when compared with controls (P less than 0.01). Plasma immunoreactive insulin concentrations were similar in athymic nudes and controls at 1 wk of age, but at 3 wk of age and subsequently at 6, 8, and 12 wk athymic nude mice had significantly decreased insulin levels when compared with their age-matched controls (P less than 0.05). We found impaired glucose tolerance in male athymic nude mice at all age groups when compared with both female athymic nudes and control BALB/c mice. The discovery of a spontaneous diabetic syndrome (hyperglycemia, impaired glucose tolerance, and decreased insulin secretion) in a colony of athymic nude mice may provide an excellent model for studying the genetics and interactions between the immune and endocrine systems.