Establishment of Transplantable Tumor Lines and in vitro Cell Lines of Malignant Thymoma Developed in a BUF/Mna Rat

A spontaneous malignant thymoma was found in an 18-month-old female BUF/Mna rat and serially transplanted subcutaneously in both syngeneic BUF/Mna rats (designated as MTH-R) and KSN nude mice (MTH-NM) for more than 5 years. Both tumors shared the histological appearance of sarcomatoid carcinoma as seen in the original tumor. However, MTH-NM grew faster than MTH-in the respective hosts. The MTH-NM grew in both KSN-nude mice and BUF/Mna- rnu/rnu rats but not in BUF/Mna rats the host of the original tumor. Three continuous tissue culture cell lines (MTHC-1, MTHC-2 and MTHC-3) were established from the MTH-NM tumors at the 2nd, 15th and 17th transplantation generations, respectively. The MTH-NM tumors and latter two tissue culture cell lines carried one or more mouse chromosomes, probably acquired by cell fusion with mouse cells during passages in vivo. The presence of the mouse chromosomes was confirmed by the presence of mouse DNA and of antibodies to the MTHC-2 and MTHC-3 cells in the sera of BUF/Mna rats transplanted with MTH-NM.     

Cytogenetic studies on rat thymic lymphomas induced by N-propyl-N-nitrosourea

N-Propyl-N-nitrosourea (PNU) was proved to be a strong leukemogen, which induces myelogenous leukemia or thymic lymphoma in rats. BUF/Mna rats and F344 rats were the strain most susceptible to thymic lymphomagenic activity of PNU. In addition, F1 rats between BUF/Mna and WKY rats were also susceptible to PNU-lymphomagenic activity. In the present experiment, karyotypes of 31 thymic lymphomas induced by PNU in BUF/Mna rats and in F1 rats between BUF/Mna and WKY rats were analysed for chromosomal abnormalities. Although no specific chromosomal abnormalities were observed throughout all lymphomas, del(11q) and dup(2q) were observed frequently in BUF/Mna rat lymphomas. Breakpoints and/or fusion-points were frequently observed in chromosome 11, followed by chromosomes 2, 5 and 6. Trisomy of chromosome 7, on which c-myc oncogene is mapped, was observed in seven cases, and monosomy of chromosomes 12, 18, 19, 20 and X was seen in seven or eight cases each, though these changes were generally observed in minor cell population in each case.     

An intrinsic thymic epithelial abnormality is responsible for the spontaneous development of predominantly lymphocytic thymomas in BUF/Mna rats.

The nature of tumorigenesis of predominantly lymphocytic thymoma was examined using an animal model. Rats of the inbred BUF/Mna strain were found spontaneously to develop predominantly lymphocytic thymomas, histologically indistinguishable from their human counterparts, at an incidence of virtually 100%. Thymic rudiments of BUF/Mna rats grafted 17 months previously under the renal capsule of young athymic ACI/NMs-rnu/rnu rats also gave rise to similar lesions. The lymphocytes in the thymomas expressed T-cell antigens (rat Lyt-1 and Lyt-2.3), as in the normal case, and ACI rat specific antigen. When BUF/Mna rats of thymoma age were irradiated with a lethal dose of 12 Gy and then received a single injection of bone marrow cells (8 x 10(7)) from BALB/c-nu/nu mice, thymomas were re-formed three weeks later (in 2 of 5 rats) with the replacement lymphocytes expressing mouse Thy-1.2 antigen. These results indicate that an intrinsic thymic epithelial abnormality is responsible for the development of predominantly lymphocytic thymomas in BUF/Mna rats.     

Chromosomal Mapping of Genetic Locus Associated with Thymus-size Enlargement in BUF/Mna Rats

The thymoma-prone rat of the BUF/Mna strain is a useful model for human thymoma. In this strain thymoma development is regulated by a single autosomal susceptible gene, Tsr-1. At pre-thymoma age, BUF/Mna rats have extremely large thyrauses, when compared to those of other strains of rats. Genetic studies in crosses between BUF/Mna rats with large thymuses and WKY/NCrj rats with small thymuses suggested the presence of a major autosomal gene, Ten-1 , which contributes to thymus enlargement in a backcross population. Linkage studies between Ten-1 and microsatellite markers in backcross rats of (WKY/NCrj×BUF/Mna)Fl×BUF/Mna have led to the localization of Ten-1 in chromosome 1. This result may provide an approach to clone Tsr-1 , which could be allelic to Ten-1.     

An Intrinsic Thymic Epithelial Abnormality Is Responsible for the Spontaneous Development of Predominantly Lymphocytic Thymomas in BUF/Mna Rats

The nature of tumorigenesis of predominantly lymphocytic thymoma was examined using an animal model. Rats of the inbred BUF/Mna strain were found spontaneously to develop predominantly lymphocytic thymomas, histologically indistinguishable from their human counterparts, at an incidence of virtually 100%. Thymic rudiments of BUF/Mna rats grafted 17 months previously under the renal capsule of young athymic ACI/NMs- rnu/rnu rats also gave rise to similar lesions. The lymphocytes in the thymomas expressed T-cell antigens (rat Lyt-1 and Lyt-2.3), as in the normal case, and ACI rat specific antigen. When BUF/Mna rats of thymoma age were irradiated with a lethal dose of 12 Gy and then received a single injection of bone marrow cells (8 × 10⁷) from BALB/c- nu/nu mice, thymomas were re-formed three weeks later (in 2 of 5 rats) with the replacement lymphocytes expressing mouse Thy-1.2 antigen. These results indicate that an intrinsic thymic epithelial abnormality is responsible for the development of predominantly lymphocytic thymomas in BUF/Mna rats.     

Surface antigens on transplantable tumor cell lines producing mouse type C viruses.

A variety of transplantable mouse tumor lines were shown to contain murine type C viruses and virus-associated antigens. The type of virus isolated and antigens detected could not invariably be correlated with the original method of tumor induction, but testing of the majority of tumor lines for infectious virus at various levels of in vivo or in vitro passage yielded isolates that were consistent in tissue culture host range for each tumor. In contrast, during the course of in vivo transplantation, some of the lines underwent considerable change in the pattern of virus-associated cell-surface antigens. When the transplanted tumor lines were placed into culture, all showed some alteration in the detectable surface antigens. Upon retransplantation and passage of the cultured cells in mice, the surface antigens gradually returned to the original in vivo patterns and occasionally acquired additional type C virus-associated antigens not detected in the original tumor line. To test for association of antigens with infectious virus, appropriate tissue culture cell lines were infected with the viruses isolated from the tumors. In these infected indicator cells, some new virus-associated cell-surface and virion evelope antigens were detected, but the complete array of antigens found in the original tumor lines was not acquired. These findings indicated the presence of several different type C viruses in long transplanted cell lines and demonstrated that environmental and host cell factors may have major influences on expression of virus-associated antigens.     

Biology, cytogenetics, and sensitivity to immunological effector cells of new head and neck squamous cell carcinoma lines

Twenty-one head and neck squamous cell carcinoma (HNSCC) cell lines were established from 89 fresh tumor specimens in order to study the biology of HNSCC lines, establish tumors in nude mice, and evaluate the sensitivity to immunological effector cells of these tumors in vitro and in vivo in nude mice. The lines were established from explants using differential trypsinization and culture for 2 to 20 mo. The explants were derived from 11 different sites. Three pairs of lines were derived from both the primary tumor and metastatic lymph nodes in the same patients. All cultures grew as either compact or diffuse adherent monolayers, and they had a median doubling time of 86 h (range, 33 to 531 h). DNA fingerprinting confirmed that the HNSCC lines were individual isolates. Thirteen of 14 lines tested induced tumors in athymic mice. The histology of each line growing in nude mice was similar to that of the original tumor tissue. Immunocytochemistry showed keratin production in all lines tested. Aneuploidy (36 to 87 chromosomes) was present in all 16 lines studied; the median chromosome number for lines derived from primary tumors was 70, whereas for lines originating from metastatic or recurrent tumors, it was 54. Karyotypic analysis showed deletion of the short arm of chromosome 3 (3p-) in 12 of 16 cell lines and trisomy 6 in 12 of 16 lines. In addition, translocations between chromosomes 9 and 11 or 9 and 12 were each present in five of 16 lines tested. The HNSCC lines were resistant to lysis by natural killer cells, but were efficiently lysed by lymphokine-activated killer cells in 4-h 51Cr release assays. These new lines have allowed us to establish a model of local adoptive immunotherapy of HNSCC in tumor-bearing nude mice, and they provide a resource for future studies of the biology of HNSCC.     

Comparison of four new cell lines from patients with adenocarcinoma of the ovary.

Permanent human tumor cell lines COLO 110, COLO 316, COLO 319, and COLO 330 were established from four patients with serous cystadenocarcinoma of the ovary. COLO 110 was derived from primary tumor tissue; COLO 316, COLO 319, and COLO 330 were derived from cells in malignant effusions. COLO 110 and COLO 316 grew as monolayers of epithelioid cells in culture; COLO 319 and COLO 330 grew as vermiform, floating colonies of epithelioid cells in culture. Epithelial-like morphology was confirmed by transmission electron microscopy. All four cell lines had marker chromosomes and double minute chromosomes. Giemsa banding revealed chromosomes 1, 3, 6, and 7 were involved in markers in all four lines, and chromosomes 2, 4, 5, 9, 11, and 15 were involved in markers in three of the cell lines. Marker chromosomes with possible homogeneous staining regions were observed in COLO 319. Estrone was elaborated by three of the lines, but neither chorionic gonadotropin, carcinoembryonic antigen, nor estrogen or progesterone receptor proteins were detected. Each cell line demonstrated a distinctive isozyme phenotype. These cell lines are maintained in active culture and in a cell bank for distribution to other investigators.     

Establishment and characterization of two human mixed mesodermal tumor cell lines from the same patient

A cell line designated HIRS -BM was established from fluid aspirated from the sternal bone marrow of a 16-year-old female. Another cell line ( HIRS -PB) was derived from the peripheral blood of the same patient. Both lines grew well, multilayering rapidly without contact inhibition, and 62 serial passages were successively done within 28 months. Both cultures contained spindle- or fibrous-shaped cells that revealed neoplastic and pleomorphic features, and these cells were characterized as possessing cross-striations in the cytoplasm. The cross-striations were detected by phosphotungstic acid hematoxylin stain. Some elongated cells were stained positively with anti-myoglobin by use of periodic acid-Schiff methods. The primary tumor in the uterus was diagnosed as a mixed mesodermal tumor composed of adenocarcinoma and rhabdomyosarcoma cells. The karyotype exhibited hyperploidy and large submetacentric marker chromosomes, and the modal chromosome number was 84. No difference was found between the 2 cell lines except for growth behavior and heterotransplantability . HIRS -BM cells grew more rapidly and were highly transplantable. The HIRS -BM cells were transplanted into the subcutis of BALB/c nude mice and produced mixed mesodermal tumors resembling the uterine tumor, while the HIRS -PB cells could not be transplanted. Due to the histogenesis of the mixed mesodermal tumor being's obscure with histologic observations only, this study was performed to obtain data by tissue culture of the tumor and resulted in support of the combination theory reported in the literature in regard to tumor.     

A single dominant susceptible gene determines spontaneous development of thymoma in BUF/Mna rat

Rats of the BUF/Mna strain developed spontaneous epithelial thymomas morphologically indistinguishable from human homologues at virtually 100% incidence. Segregation of thymoma development among crosses between BUF/Mna and ACI/NMs, which has 0% thymoma incidence, indicated that thymoma susceptibility was determined principally by a single autosomal dominant gene Tbm-1 (thymoma in BUF/Mna rats). In these crosses, another autosomal dominant or semidominant gene(s) contributed by ACI/NMs parents moderately reduced the thymoma incidence.     

Establishment and characterization of human signet ring cell gastric carcinoma cell lines with amplification of the c-myc oncogene.

Two unique human signet ring cell gastric carcinoma cell lines (designated HSC-39 and HSC-40A) were established in vitro from the ascites of a 54-year-old male patient. Both cell lines were biologically quite similar, grew in vitro in suspension with a population doubling time of 28-30 h, and had cytological features of mucinous epithelial tumor cells. They formed colonies in soft agar, with a cloning efficiency of 0.8-1.0%. Ultrastructurally, numerous granules were observed in the cytoplasm, suggesting secretory activity. The frequent presence of desmosome and the tight junction at the cell boundary certifies the epithelial origin of the lines. Immunocytochemistry and radioimmunoassay showed production of tumor marker antigens (carcinoembryonic antigen, CA 19-9, and sialyl-Lex-i) and gastrin in both lines. These lines were transplantable in athymic BALB/c nude mice. The histopathology of each line growing in athymic BALB/c nude mice was similar to that of the original tumor. The karyotype of the cells was highly aberrant with structural and numerical changes. The presence of numerous double minute chromosomes and loss of the 13 chromosome and Y-chromosome characterize these lines. In addition, the amplified c-myc oncogene (16-32-fold) was found in both cell lines and original ascitic tumor cells. Overexpression of the c-myc mRNA was noted. These cell lines may be a useful tool, providing both in vivo and in vitro systems for further studies of the biology and therapy of human signet ring cell (or Borrmann's type IV carcinoma) gastric carcinoma.     

Tumor-cytotoxicity of nitric-oxide produced from alveolar macrophages directly stimulated with tumor-cells

Macrophages activated by lipopolysaccharide or interferon-gamma have been shown to be cytotoxic to tumor cells by releasing nitric oxide. Here, we report that unstimulated rat alveolar macrophages cultured with certain tumor cells produce nitric oxide and are cytotoxic to these tumor cells. Alveolar macrophages were taken from BUF/Mna rats, which were known to produce spontaneous thymoma, and cultured with syngeneic BUF/Mna-derived thymoma cells. They were killed by syngeneic or allogeneic alveolar macrophages and this killing was partially abolished by addition of N(G)-monomethyl-L-arginine. X-ray irradiated, mitomycin C-treated or membranous fragments of BUF/Mna-derived thymoma cells directly stimulated rat alveolar macrophages to produce nitric oxide.     

Excess chromosome no. 4 in ethylnitrosourea-induced neurogenic tumor lines of the rat

The chromosomes in 15 cell lines derived from separate tumors induced in rats by ethylnitrosourea (ENU) are described. Thirteen lines were neural (glioma or schwannoma) in origin and type. In 12 of these lines, excess chromosome no. 4 could be demonstrated by Giemsa banding. One to three extra no. 4 chromosomes were seen as numerical or structural abnormalities. Also noted were other changes that were not consistent among lines. The 12 lines produced tumors in newborn rats. The 13th neurogenic line lacked excess chromosome no. 4 and did not produce tumors. The remaining 2 lines were nonneurogenic and lacked excess chromosome no. 4 but produced tumors. Control studies included chromosome analyses of bone marrow preparations from ENU-treated rats with tumors, cell lines from brains of normal rat embryos, and 2 established nonneurogenic rat tumor lines. No excess chromosome no. 4 was seen. These results suggest that nondisjunction and/or rearrangement of chromosome no. 4 is associated with the oncogenic process in neurogenic tumors induced.     

Human renal carcinoma: characterization of five new cell lines

Five human renal carcinoma cell lines have been established in long-term tissue culture. Two of the cell lines, UM-RC-2 and UM-RC-3, produced clear cell tumors in athymic nude mice. The cell lines have been characterized by staining with oil red O, doubling time in vitro, and number of chromosomes. Although protein A assay reactivity of autologous combinations of patient's sera and tumor cells were seen with all five cell lines, similar binding was also found with autologous normal kidney cultures. However, the immune adherence assay demonstrated low titer autologous reactivity with two renal carcinoma cell lines but not with the corresponding normal kidney cultures. This strongly suggest host recognition of tumor-associated antigens. Characterization of cell surface antigens with murine monoclonal antibodies demonstrated shared reactivity between normal kidney tubular cells and renal carcinoma cells. Antibody A68.11 reacted strongly with all five cell lines. Antibody A80 bound to only UM-RC-3 and UM-RC-6.     

Transplantable mouse tumor line induced by injection of SV40-transformed mouse kidney cells

A transplantable tumor of inbred mice was obtained by inoculating BALB/c mice subcutaneously with SV40-transformed mouse kidney (mKS-A) cells. Tumors were produced by mKS-A cells in the 71st cell culture passage, but not by cells in the 26th passage. The tumor line has been serially passed in BALB/c mice 14 times. In vitro cell culture lines were derived from tumors after 1, 2, 8, 10 and 12 passages in mice. The tumors, as well as the In vitro tumor cell lines, contained SV40 T-antigen, and sera from the tumor-bearing mice contained antibodies to the SV40 T-antigen. SV40 was rescued from the In vitro tumor cell lines after fusion with green monkey kidney (CV-1) cells in the presence of UV-irradiated Sendai virus. The In vitro tumor cell lines derived from mouse passages 8, 10 and 12 were used as SV40 virus; 2) SV40-transformed cell lines; 3) primary mouse (BALB/c or Yale Swiss) kidney cells, or 4) primary mouse (BALB/c or Yale Swiss) embryo cells. These results showed that the tumor line and the In vitro tumor cell lines have the transplantation antigen.     

Giant cell carcinomas of the lung producing colony-stimulating factor in vitro and in vivo

Two culture cell lines (C-Lu65, C-Lu99) were established from human giant cell carcinomas of the lung transplanted in athymic nude mice (BALB/c, nu/nu). During early passage in tissue culture, C-Lu65 grew as a loosely adherent monolayer with some piling-up and with floating cells. After 30 successive subcultures, C-Lu65 began to grow in suspended cell clusters, showing a faster growth rate. C-Lu65 was characterized by multinucleated giant cells with large abnormal nuclei and prominent nucleoli. C-Lu99 grew as adherent cells, and fewer multinucleated giant cells were observed. C-Lu65 and C-Lu99 showed some ultrastructural differences in cell surface and cytoplasmic features. Chromosomal analysis revealed numerical and structural abnormalities in both cell lines. Cell-free supernatants from both cell lines stimulated the colony formation of mouse bone marrow cells in vitro. In addition, mice bearing tumors induced by transplanting C-Lu65 and C-Lu99 showed remarkable leukocytosis without evidence of infection. These results suggest that these two cell lines release colony-stimulating factor both in vitro and in vivo.     

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.     

Growth in culture and tumorigenicity after transfection with the ras oncogene of liver epithelial cells from carcinogen-treated rats

Two epithelial cell lines designated LE/2 and LE/6 were established from cells isolated by centrifugal elutriation from the livers of carcinogen-treated rats. Both cell lines exhibit some characteristics of fetal liver cells, such as the expression of the 2.3-kilobase alpha-fetoprotein mRNA, aldolase A, and lactate dehydrogenases 4 and 5. Primary cultures contain gamma-glutamyl transferase-positive cells which do not proliferate in vitro. After the first passage, the LE/2 and LE/6 cell lines are uniformly gamma-glutamyl transferase negative. Neither cell line is transformed as assayed by morphology, anchorage-independent growth, or tumor formation in nude mice. By the 50th passage, LE/6 cells form numerous colonies in soft agar in the presence of epidermal growth factor, while no colonies grow in medium lacking this growth factor. Clonal cell populations derived from five epidermal growth factor-induced soft agar colonies were not tumorigenic in nude mice. This indicates that, although epidermal growth factor-responsive late passage cells had acquired some of the phenotypic properties commonly associated with tumor cells, these cells were not fully transformed. Transformation of LE/6 cells was accomplished by transfection of the rasH oncogene (EJ). Subcutaneous inoculation of rasH (EJ)-transfected LE/6 cells produced tumors at the site of injection with histological features of moderate to well-differentiated trabecular hepatocellular carcinomas. Tumor cell lines derived from the nude mouse tumors are gamma-glutamyl transferase positive and express alpha-fetoprotein mRNA. One clonal cell line expresses both alpha-fetoprotein and albumin mRNA. These results show that nonparenchymal liver epithelial cells transfected with an activated oncogene can give rise to differentiated hepatocellular tumors similar to those induced in livers of rats fed a carcinogenic diet.     

The rate of homozygous CDKN2A/p16 deletions in glioma cell lines and in primary tumors.

The rate of homozygous deletions of CDKN2A/p16 is variable between different tumor entities, and in addition it is higher in established cell lines in comparison with primary tumors. Such incongruencies may reflect statistical sampling errors, true differences depending on tissue derivatisation and CDKN2A/p16 loss under selective pressure in tissue culture. Clarification of these issues is warranted in the context of defining tumor suppressor genes such as CDKN2A/p16 as targets for gene replacement therapies. We therefore compared established cell lines derived from human glioblastomas and their corresponding primary tumors by multiplex PCR methodology. Archival early passages were included to determine the time point at which the p16 status of a cell line changes if it is different from the original tumor. It was found that in 2 of 11 cases (18%) the primary tumor had no p16 alteration whereas the corresponding cell lines had a homozygous p16 deletion. Tracking the in vitro evolution of these two cell lines we found that CDKN2A/p16 was lost already in the earliest passages. This suggests a clonal outgrowth advantage of a subpopulation of p16 deleted tumor cells rather than instability of the CDKN2A/p16 genotype in vitro. Including 20 additional glioblastoma-derived cell lines we detected that in 19 of the total 31 lines at least one exon was lost bringing the rate of p16 loss in the whole panel to 61%. This compares to a rate of 49% which was found in original glioma tissue from 47 unselected other patients. It is concluded, that in cell culture selective pressure favours the outgrowth of pre-existing CDKN2A/p16 negative clones, which account for the difference of CDKN2A/p16 status between cell lines and tumors. In no case did we see a change of the CDKN2A/p16 status during prolonged tissue culture periods of up to 8 years.     

Biological properties of cell lines derived from Moloney virus-induced sarcoma.

Two cell lines derived from a primary MSV-M-induced tumor in a BALB/c mouse were studied. One line (MS-2) was subject only to continuous tissue culture transfer (tct). After 21 tct, MS-2 cells produced progressive tumors (MS-2 tumors) in syngeneic hosts. The second cell line (MS-2T) was established by cultivation of a MS-2 tumor. The ability to produce progressive tumors decreased with increased number of tct, in both cell lines. The virus content of MS-2 and MS-2T cells was very low, as shown by uridine incorporation and electron microscopy. Immmunofluorescence tests demonstrated that antigens different from the viral MSV-M antigens were present on the cell lines, and that antigenic changes occurred with increased number of tct. Serum of mice bearing progressive MS-2 tumors reacted with MS-2T cells when these cells produced progressive tumors and did not react with MS-2 cells when they produced regressing tumors. MS-2 cells producing regressing tumors reacted with serum from mice in which the MS-2 tumor had regressed and with serum from mice immunized with MS-2T cells at late tct when they were poorly oncogenic. The antigenic changes seemed, therefore, to parallel the decrease of malignancy. A chromosomal analysis carried out on MS-2 and MS-2T cells, when both produced progressive tumors, showed a modal number of 48 and 44, respectively. MS-2T cells showed a large acrocentric chromosome. In contrast, the MS-2 cells at late tct, when they gave regressing tumors, showed a modal number of 60 and a wide range of distribution of chromosome number.