Growth characteristics of clonal cell populations constituting a B16 melanoma metastasis model system

Three distinct dissemination-related phenotypes have been distinguished among cell subpopulations of the mouse B16 melanoma: tumorigenicity, spontaneous metastasis from subcutaneous tumors, and organ colonization following intravenous injection of cells. From a progenitor clone (G3) of tumorigenic but nonmetastatic and noncolonizing (null) cells that underwent phenotypic diversification in vitro and in vivo, 4 subclones were obtained: G3.5 (culture-generated metastatic), G3.12 (tumor-generated metastatic), G3.15 (culture-generated null), and G3.26 (tumor-generated colonizing). The growth potentials of the parent clone and derived subclones were investigated comparatively in in vivo assays (tumorigenicity, tumor growth rate, and lung colonization potential), monolayer culture assays (generation time, saturation density, clonogenicity, and rate of detachment by trypsin), and in soft agar. In overall growth potential, G3.26 greater than G3.12 greater than G3, G3.5 greater than G3.15. These results indicate that metastatic populations of the B16 melanoma are not the most rapidly and effectively growing cells obtainable from that tumor.     

Relative tumorigenicities of hybrid cells with and without HSR-bearing chromosomes from a human melanoma cell line

Some cell types within the human melanoma cell line MeWo contain homogeneously staining regions (HSRs) consisting of repetitive DNA sequences and ribosomal RNA (rRNA) genes derived from chromosome 15. To further examine the association between enhanced tumorigenicity and the presence of HSR-bearing chromosomes, hybrid cell lines were constructed by fusing X-HSR-containing MeWo cells with ouabain-resistant, HPRT-deficient Chinese hamster ovary cells and culturing in HAT medium containing ouabain. A hybrid containing the X-HSR chromosome and several MeWo chromosomes was more tumorigenic in BALB/c nude mice than derivative cells lacking the X-HSR and human chromosome 18. However, since this enhanced tumorigenicity could be due to sequences on either the X-HSR or chromosome 18, a second series of hybrids was constructed by micro-cell fusion. In this case, the tumorigenicity of hybrid cells containing 2 copies of the X-HSR as the only MeWo chromosome was similar to that of derivative cells lacking these chromosomes. Cytogenetic analysis revealed that the nucleolar organizer regions (NORs) on the HSR were inactive in the hybrid cells. Our data indicate that DNA sequences amplified on MeWo HSRs do not enhance tumorigenicity under experimental conditions in which rRNA genes are not expressed. As the only active NORs in MeWo HSR-containing cells are on the HSRs, we suggest that expression of these amplified rRNA genes is responsible for the selective growth advantage of these cell types in nude mice. Our data also indicate that the enhanced tumorigenicity of MeWo HSR-containing cells is not due to co-amplification of a dominant oncogene.     

Correlation between characteristics of transformation and malignancy of intra and interspecific somatic hybrid cells

The transformed properties of five hybrid cell lines which had either one or another parent in common were studied and compared with their tumorigenicity. Three hybrid cell lines, derived from the Chinese hamster DC-3F/ADX/Aza line, were resistant to actinomycin-D. This property seemed to be correlated with the presence of a marker chromosome from the common parent. The tumorigenicity was intermediate between those of the parent cell lines. On the other hand, agglutinability by concanavalin A (Con A) was variable. Three hybrid cell lines which had either the A9 or the clone 1D (both derived from mouse fibroblasts) showed very similar transformed characteristics, but two were tumorigenic and one not so. It appears from this study that the properties of the hybrid cell lines can be influenced more by one parent, depending on the genes retained at chromosome segregation. The limits of Con A agglutination as a characteristic of transformation and the validity of the check pouch grafts as tumorigenicity test for malignant human cell lines are discussed.     

Modulatory effects of 5-azacytidine, phorbol ester, and retinoic acid on the malignant phenotype of human lung cancer cells

Cloned human cell lines of squamous-cell lung carcinoma and small-cell lung carcinoma were treated with 5-azacytidine (5-azaC), 12-0-tetradecanoyl-phorbol-13 acetate (TPA), retinoic acid (RA), or a combination of these drugs, and the effects on cellular morphology, in vitro growth properties, antigenicity, tumorigenicity and metastatic activity in nude mice were studied. Antigenicity was measured by the expression of major histocompatibility antigens (MHC) and of lung-tumor-associated antigens. 5-AzaC treatment resulted in subclones with shorter population doubling times (from 40-50 hr down to 14-20 hr) and increased cloning efficiencies (from less than 1% to 5-50%). TPA and RA induced loss of proliferative activity in vitro and tumorigenicity in vivo of both lines. This was morphologically associated with the appearance of an abundance of large vaculated cells which by DNA-analysis were all found to be in G0-G1 phase. However, 2 of the 5-azaC-treated subclones were insensitive to both TPA and RA, whereas the remaining subclones (20) all responded like untreated lines to TPA and RA. One of the sublines insensitive to TPA and RA formed metastases in nude mice in contrast to all the other lines used. The density of lung-tumor-associated antigens was significantly reduced by TPA-RA treatment, whereas the expression of MHC antigens was unaffected. In contrast, 5-azaC resulted in some cases in increased density of MHC antigens. The effects of 5-azaC on cellular phenotypes were not directly correlated to the total genomic content of 5-methylcytosine. The data suggest that this experimental system is suitable for studies of phenotypic features of malignant cells as related to cellular differentiation.     

Modification of myc gene amplification in human somatic cell hybrids

In order to study whether cell fusion would modify the DNA copy number of an amplified oncogene, somatic cell hybrids were made between the human neuroepithelioma cell line MCIXC and HeLaCOT human adenocarcinoma cells. MCIXC contains approximately 21 copies of the c-myc oncogene and HeLaCOT contains approximately 5 copies relative to the control. All hybrid clones investigated displayed a marked decrease in the number of copies of c-myc DNA (an average of 5 copies), while the level of c-myc RNA in the hybrids was similar to that found in both parents. All eight hybrid clones were found to be completely nontumorigenic even though both parent cells formed tumors in 100% of the nude mice treated by injection. This loss of oncogene amplification in the hybrids was shown not to be due to either heterogeneity of c-myc amplification in the MCIXC parent or segregation of a copy of the chromosome 22 from the hybrids. This loss most likely resulted from the breakdown of a homogeneously staining region (containing the amplified gene copies) into double minutes, which were subsequently lost from the cells. The HeLaCOT cell line was also fused to the human neuroblastoma BE(2)C, which contains approximately 123 copies of the N-myc oncogene relative to control. Ten hybrid clones were found to contain an average of 47 copies of N-myc DNA, significantly less than the 91 copies predicted had no loss occurred. These BE(2)C x HeLaCOT hybrids expressed on average about 15% the N-myc RNA seen in the BE(2)C parent and, as with the MCIXC x HeLaCOT hybrids, were found to be completely nontumorigenic. However, upon passage in culture, one BE(2)C x HeLaCOT hybrid eventually became tumorigenic. This hybrid also displayed reduced copies of N-myc DNA in comparison to its parent hybrid but surprisingly showed a 2-fold increase in N-myc RNA. Thus, the expression of N-myc, but not the amplification state of either myc gene, appears to correlate with the tumorigenicity of the cells.     

Damage and repair induced by bleomycin in the domain of human amplified MYC oncogenes.

Growing monolayer COLO320 human cells having a 30- to 40-fold amplification of a MYC domain were pulse treated for 15 min with increasing doses of bleomycin (BLM). Cellular DNA was extracted at the end of the BLM treatment or after an interval of 30 min, during which the cells were allowed to repair the DNA damage at 37 degrees C in culture medium without BLM. Damage and repair in total cellular DNA was assessed by alkaline unwinding and by neutral and alkaline gel electrophoresis. The response to BLM in the domain of MYC oncogene was evaluated by Southern blotting of EcoRI-digested DNAs separated by neutral or alkaline gel electrophoresis. We found that MYC domains from COLO320HSR showed a higher frequency of double-strand DNA breaks than MYC domains from COLO320DM cells. At the level of total cellular DNA, both cell lines showed the same frequency of double-strand nicks. No repair of double-strand breaks was observed. Total DNA from COLO320HSR cells was more sensitive to single-strand breakage than DNA from COLO320DM. At the gene level, the frequency of single-strand scissions was higher in COLO320DM than in COLO320HSR MYC domains. Both cell lines had good capability to close single-strand scissions. However, at high BLM doses the damage was more efficiently repaired by COLO320DM cells. We propose that chromatin organization in total cellular DNA and in the amplified MYC domain probably plays an important role in the DNA response to BLM.     

Characterization in vitro and in vivo of progressively adriamycin-resistant B16-BL6 mouse melanoma cells

Adriamycin (ADR)-resistant sublines of B16-BL6 mouse melanoma selected by exposure to increasing concentrations of ADR were characterized in vitro for growth properties and in vivo for tumorigenicity and pulmonary metastases. The progressively resistant sublines adapted to grow in the presence of 0.025, 0.05, 0.1, and 0.25 microgram/ml ADR in monolayer culture were found to be 5-, 10-, 20-, and 40-fold ADR-resistant, respectively, compared to the parental sensitive cells, using a soft-agar colony assay and continuous ADR treatment for 7 days. The doubling time in monolayer culture of the parent sensitive and progressively ADR-resistant sublines of B16-BL6 melanoma cells was approximately 16-18 h. Although the colony-forming efficiency in soft agar of parental sensitive cells was only 0.5-4%, the 5-, 10-, 20-, and 40-fold ADR-resistant sublines had colony-forming efficiencies of 15, 20, 30, and 77%, respectively. Tumorigenicity in C57BL/6 mice of progressively ADR-resistant sublines was similar to parental sensitive cells following s.c. and i.p. implantation of 10(5)-10(6) tumor cells. Experimental pulmonary metastases were significantly lower in ADR-resistant sublines with progressive resistance. Additionally, unlike the parental sensitive and 5-fold ADR-resistant B16-BL6 cells, the 10-, 20-, and 40-fold ADR-resistant sublines were spontaneously nonmetastatic. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunochemical detection of P-glycoprotein revealed the presence of a Mr 170,000 plasma membrane glycoprotein in the 40-fold ADR-resistant subline and its counterpart maintained for 1 year in ADR-free medium. Results from this study suggest that progressively ADR-resistant B16-BL6 mouse melanoma cells selected in vitro demonstrate a marked increase in colony formation in soft agar and a decrease in the ability to produce pulmonary metastases, without alterations in tumorigenicity.     

Non-random chromosome changes in a herpes-virus-transformed syrian hamster cell line and its metastatic derivatives

A primary subcutaneous tumour of low spontaneous metastatic capacity, produced after inoculation of Herpesvirus hominis type-2-transformed hamster fibroblasts (parent line) and two in vivo derived highly metastatic lung deposits (Met A and Met B) were karyotyped and compared after trypsin G-banding. The parent line was cytogenetically heterogeneous with a modal chromosome number of 74. However, a number of cells were of a higher ploidy level. A large variation in both numerical and structural abnormalities was observed, the chromosome rearrangements were often complex and unstable, but all the cells contained a theme of common marker chromosomes. Met A and Met B were near diploid (mean chromosome numbers 42 and 44 respectively) with a low level of tetraploid cells. They shared many chromosome rearrangements but could be readily distinguished by an additional translocation unique to Met A. Cytogenetic homogeneity within and between metastases suggested that they were of monoclonal origin and had been derived from a karyotypically similar subpopulation within the parent tumour. We were unable to detect such cells in the parent line; thus, their numbers within the parent tumour were likely to be low. Metastasis, therefore, has been highly selective, depending on the particular phenotypic properties of Met A and Met B. All cells of the parent and metastatic lines have homogeneously staining regions (HSR) and abnormalities of chromosomes 15 (C15) which may be important in tumorigenesis. In addition, Met A and Met B cells have a number of chromosome rearrangements [translotions, deletions and a double minute chromosome (DM)] not present in the parent cells. They are retained at a high frequency in the cells of Met A and Met B and thus it seems likely that the metastatic phenotype is associated with one or more of these chromosome aberrations.     

Phenotypic modulation during tumorigenesis by clones of transformed rat liver epithelial cells

From nine clonal subpopulations (strains) of chemically transformed cultured rat hepatic epithelial cells which were tumorigenic when implanted into 1-day-old isogeneic rats, a cell line was reestablished from each tumor and the cellular properties of the tumor-derived cell lines were compared to those of the corresponding progenitor cells that were implanted to produce the tumors. In seven of eight instances, the cellular DNA content of the tumor-derived cells was virtually identical to the DNA content of the respective progenitor cells, but in one case the tumor cells had twice as much DNA as did their progenitor cells. During the development of tumors in vivo, other cellular phenotypic properties often underwent considerable, but variable changes. These changes included the activity of gamma-glutamyl transpeptidase, the growth properties on plastic surfaces, and the expression of LDH isozymes. Although there was a relative enhancement in the ability of most of the tumor-derived cells to proliferate or to form colonies in calcium-poor medium, several tumor-derived cell lines had very low colony-forming efficiencies in media containing either normal or low levels of calcium. The most consistent association between phenotypes expressed in vitro and tumorigenicity was the ability of cells to form colonies in soft agar; all tumor-derived lines expressed this phenotype, and with some of them this phenotype was acquired only during the process of tumor formation in vivo. These results demonstrate that further phenotypic and genotypic alterations may occur in vivo during tumor formation by chemically transformed cultured cells following their implantation into isogeneic animals; and some of the alterations that occur in vivo may be necessary for the complete expression of tumorigenicity. Although anchorage-independent growth capacity cannot be used to predict the tumorigenicity of clones of rat liver epithelial cells chemically transformed in vitro, this growth property appears to be invariably induced prior to or during the formation of tumors in vivo by these cells.     

Multiple human chromosomes carrying tumor-suppressor functions for the mouse melanoma cell line B16-F10, identified by microcell-mediated chromosome transfer

Many tumor-suppressor genes are involved in the development and progression of cellular malignancy. To understand the functional role of tumor-suppressor genes in melanoma and to identify the human chromosome that carries these genes, we transferred individually each normal human chromosome, except for the Y chromosome, into the mouse melanoma cell line B16-F10, by microcell fusion. We examined the tumorigenicity of hybrid cells in nude mice and their in vitro growth properties. The introduction of human chromosomes 1 and 2 elicited a remarkable change in cell morphologic features, and cellular senescence was induced at seven to 10 population doublings. The growth rates of tumors derived from microcell hybrid clones containing introduced human chromosome 5, 7, 9, 10, 11, 13, 14, 15, 16, 19, 20, 21, 22, or X were significantly slower than that of the parental B16-F10 cells, whereas the introduction of other human chromosomes had no effect on the tumorigenicity of these cells. The majority of microcell hybrid clones that exhibited suppressed tumorigenicity also showed a moderate reduction in doubling time compared with B16-F10 cells. Microcell hybrid clones with an introduced human chromosome 5 showed complete suppression of in vitro-transformed phenotypes, including cell growth, saturation density, and colony-forming efficiency in soft agar. Thus, these results indicated the presence of many cell senescence-related genes and putative tumor-suppressor genes for the mouse melanoma cell line B16-F10 and showed in vitro that many tumor-suppressor genes control the phenotypes of transformed cells in the multistep process of neoplastic development.     

Tumorigenicity of T lymphoma/T lymphoma hybrids and T lymphoma/normal cell hybrids

Stable hybrids formed between clones of established murine T-cell lymphoma lines, and between lymphoma clones and normal spleen or thymus cells were examined for their tumorigenic properties by intravenous (i.v.) and intradermal (i.d.) inoculation into syngeneic AKR mice. Fusion parents consisted of T lymphoma clones of high and low tumorigenicity derived from the SL 12 cell line. In addition, normal spleen cells and thymocytes were fused with poorly tumorigenic T-lymphoma clones. Hybrids tested by i.v. inoculation of 10(6) cells to syngeneic hosts showed that fusion between the lymphoma cells resulted in hybrids which displayed the phenotype of the highly tumorigenic parent. Also, it was shown that fusion of poorly tumorigenic lymphoma cells with normal spleen cells resulted in hybrids with enhanced tumorigenicity. Fusion of poorly tumorigenic lymphoma cells with normal thymocytes resulted in hybrids with the highest tumorigenic potential. The pattern of spread for the tumor/tumor hybrid was that of the highly tumorigenic parent. Tumor spread patterns for the spleen/tumor hybrids were different from those of the thymocyte/tumor hybrids. Intradermal inoculation of 10(5) cells from tumor/spleen or tumor/thymocyte hybrids revealed differences in latent periods between parental and hybrid cells, the tumor/thymocyte hybrids having the shortest latent period. Surface marker studies and T-cell antigen receptor mRNA determinations in the tumor cell/normal cell hybrids indicated that the normal parent was a cell of immature phenotype. Therefore, high tumorigenicity is a dominant characteristic, and poorly tumorigenic but "immortal" T lymphoma cells can derive characteristics which increase their in vivo growth capacity from the putative immature normal cells with which they selectively fuse.     

UPRT/5-FU前药转换酶系统对小鼠胃癌治疗的实验研究

目的　探讨UPRT/ 5 FU前药转换酶系统对小鼠胃癌细胞MFC的杀伤效应。方法　采用PCR技术从大肠杆菌K12基因组中扩增UPRT基因 ,并构建pLXSN逆转录病毒表达载体 ,进一步转染MFC细胞。采用MTT法检测转导UPRT基因前后 ,MFC对 5 FU的敏感性的变化。建立 6 15小鼠胃癌皮下移植瘤模型 ,腹腔内给于 5 FU ,观察治疗效果。结果　体外MTT法检测结果显示 ,转导UPRT基因后可使MFC对 5 FU的敏感性提高约 17.2 6倍。动物实验的结果表明 ,转导UPRT基因不影响MFC的致瘤性 ;经 5 FU治疗后 ,转UPRT基因的肿瘤 ,生长明显受抑 (P <0 .0 0 0 5 ) ,抑瘤率为 89.6 2 %。结论　UPRT基因修饰小鼠胃癌细胞株MFC ,能明显提高MFC对 5 FU杀伤的敏感性 ,增强 5 FU的抗瘤效应。     

CLU基因干扰质粒的构建及其对鼻咽癌细胞生物学功能的影响

目的 构建CLU基因干扰重组质粒及建立CLU基因干扰转染鼻咽癌细胞及动物模型,检测CLU对鼻咽癌细胞生物学功能的影响。方法 首先以real-time PCR和Western blot法验证CLU在鼻咽癌细胞系5-8F,6-10B中的表达,以高表达CLU的5-8F细胞作为干扰转染的目标细胞;设计及构建shRNA表达载体pSR-GFP/Neo-CLU-shRNA,将其转染至5-8F鼻咽癌细胞系中,通过Transwell小室迁移及侵袭实验来检测对其迁移和侵袭功能的影响。结果 与6-10B细胞比较,CLU基因在5-8F中的表达显著上调（P<0.05）;干扰鼻咽癌细胞5-8F中的CLU可使细胞迁移和侵袭功能明显减弱（P<0.05）,使其体外成瘤能力显著降低（P<0.05）。结论 CLU基因在鼻咽癌细胞系5-8F中明显高表达;pSR-GFP/Neo-CLUshRNA 可成功干扰5-8F中CLU的表达;CLU可抑制5-8F细胞的迁移、侵袭及体内成瘤能力。     

Somatic cell hybrids of the Djungarian hamster: malignancy and evolution of the karyotype

Djungarian hamster somatic cell hybrids were obtained by fusing malignant SV40-transformed fibroblasts (line DM15, HGPRT-), and normal male lymphoid cells. Tumorigenicity, growth in soft agar and karyotype changes of 10 independent hybrid clones were studied. All hybrids grew as tumors after injection of new-born hamsters with 1 x 10(6) cells. A total of 313 tumors occurred in 523 hamsters. The hybrids proliferated in soft agar as well. No correlation was noted between the ability of hybrids to grow in vivo and to form colonies in soft agar. The total chromosome number in hybrid cells was usually less than the expected sum of the parental chromosome sets. G-banding analysis showed that, in vitro, hybrids lost chromosomes of the normal parent, whereas marker chromosomes of the malignant parent were retained. In the majority of hybrid tumors the chromosome set was reduced to the diploid range. In tumors with a slightly reduced karyotype one or two homologues of chromosomes #4 and #8 were, as a rule, eliminated.     

Radiation and thermal sensitivities of murine tumor (FSa-II) cells recurrent after a heavy irradiation.

Radiation and thermal sensitivities, and cell doubling times (Tds) of C3Hf/Sed mouse FSa-II cells recurring after a heavy irradiation were examined in vitro. Tumors in the leg were irradiated with gamma-rays and observed for late recurrence (in vivo clones), or removed immediately after irradiation and single cell suspensions were plated for colony formation (in vitro clones). Five subclones were selected from original cells in vitro. Survival curves were fitted to the multi-target and linear quadratic models. Surviving fractions at 2 (SF2) and 10 Gy (SF10) irradiations, and those at 30 and 60 min heatings at 44 degrees C (SF30 and SF60), were obtained for each clone. Although, Tds of subclones were slightly longer than those of the parental cells, those of recurrent clones were prolonged substantially with an exception of one cell line. Radiosensitivities of FSa-II parental cells tested in vitro and in vivo were equally radioresistant. Thermal sensitivities of parental cells tested in vitro and in vivo were also identical. All subclones were more radiosensitive compared to the parental cells. The in vitro recurrent clones showed smaller D0 (radiation dose to reduce survival from S to S/e in the exponential portion of survival curve) than the D0 of the parental cells. The SF2 values of four in vitro recurrent clones were greater than that of the parental cells whereas those of two lines were smaller. It was of interest that the in vivo recurrent tumor cells showed a wide variation in the radiation sensitivity. Among 9 tumor cell lines examined, 4 lines were more sensitive and 4 were more resistant compared to the original. FSa-II subclones as well as both in vitro and in vivo recurrent clones showed a wide variation in thermal sensitivity. No consistent changes in the shoulder or in the slope were found. The SF30 or SF60 showed that 5 out of 9 in vivo recurrent clones and 4 out of 9 in vitro clones were more resistant compared to the original cells. No correlation was observed between thermal and radiation sensitivities. The Td was not related with radiation or thermal sensitivity.     

Inheritance of immunogenicity and metastatic potential in murine cell hybrids from the T-lymphoma ESb08 and normal spleen lymphocytes

T-lymphoma cells were fused with normal lymphoid cells to examine the segregation of tumorigenicity and metastatic capacity in the hybrids. In independent fusions the immunogenic ESb08 T-lymphoma line fused successfully with normal syngeneic spleen cells (from DBA/2 and CD1 mice) enriched either with T-cells or B-cells. Ten times fewer hybrids were obtained with B-cells compared to the number obtained with T-cells, and marker assays showed that both types of fusions preferentially generated T-T hybridomas. Some of the hybrids resembled their tumor parent in their ability to form primary and secondary tumors only in irradiated DBA/2 mice, whereas other hybrids lost the high ESb08 immunogenicity, were equally tumorigenic, and in some cases metastatic, in nonirradiated mice. DNA distributions of the original hybrid lines ranged from a hexaploid DNA content (expected for complete hybrids derived from a tetraploid line and normal diploid cells) to a tetraploid DNA content, confirming the reported chromosome instability of T-T hybrids. No correlation was noted between the initial DNA content and tumorigenicity, but in the case of complete hybrids, reduction in the ploidy levels always was observed in the cells of primary and metastatic lesions. One chromosomally stable and highly malignant hybrid (C2), which was analyzed for segregation of chromosomes and for drug-resistance markers, showed preferential loss of chromosomes from the normal T-cell fusion partner. The decreased immunogenicity of this hybrid could not be related to any detectable loss of chromosomes from the ESb08 tumor parent.     

Inhibition of growth of B16 melanoma by glucocorticoids does not result directly from receptor-mediated inhibition of tumour cells

The ability of dexamethasone (DM) to slow the growth of B16 melanoma in C57B1 mice was confirmed. Inhibition was dose-related and was demonstrated in the use of established tumours as well as initial transplants. Although glucocorticoid receptors (GR) were present in cultured tumour cells, DM did not reduce growth of B16 in vitro, even at high concentration. This dissociation of effect on growth in vivo and in vitro suggests that DM slows B16 tumour growth in vivo by mechanisms other than GR-mediated inhibition of tumour cells.     

Comparative in vivo and in vitro proliferation of murine tumor cells in the bone microenvironment

To examine the effect of bone microenvironmental factors on the growth of metastatic cells, the in vivo proliferative features of three murine cell lines were determined at skeletal metastatic sites and correlated with their ability to grow in vitro in the presence of bone-derived factors. Bones, ovaries, adrenals and the brain were most affected by metastasis, following an intraarterial injection of B16/F1 and B16/F10 melanoma and FS/L10 fibrosarcoma cells into C57BL/6 mice. Melanoma cells showed a marked metastatic preference for bone, while fibrosarcoma cells developed brain metastasis in all animals. Tumor burden in bones was highest (19+/-2%) for B16/F10 cells, compared to B16/F1 (10+/-2%) or FS/L10 (3+/-1%) cells. Autoradiographic studies demonstrated organ- and cell type-specific differences in tumor cell proliferation, with B16/F10 cells displaying the lowest labelling indexes in bone (12+/-2% for B16/F10 vs 28+/-2% and 27+/-4% for B16/F1 and FS/L10 cells, respectively). To test if bone-derived factors differentially affected tumor cell growth in these three cell lines H-3-thymidine uptake by these tumor cells was assessed after in vitro incubation with bone-derived conditioned medium. Under these conditions, we observed stimulation of B16/F10 cell proliferation, but inhibition of uptake in the other two cell lines. Thus, these results demonstrate that, in this in vivo experimental model, growth properties of metastatic cells are organ- and cell type-specific. Additionally, we show that the in vitro proliferative behavior of tumor cells in the presence of bone-derived factors correlates and may predict skeletal tumor growth properties in vivo.     

腺病毒介导的大肠杆菌CD自杀基因体内外对肿瘤杀伤作用的研究

编委会 Editorial Board名誉主编 Honorary Editor-in-chief吴孟超 Wu Meng chao(Second Military Medical University,Shanghai 200433学术顾问 Academic Advisers巴德年 Ba Denian(Chinese Academy of Medical Sciences,Beijing 100730)刘新垣 Liu Xinyuan(Shanghai Institute of Biochemistry,Chinese Academy of Sciences,Shanghai 200031)吴旻 WuMin(Cancer Institute,Chinese Academy of Medical Sciences,Beijing 100021)汤钊猷 Tang Zhaoyou(Shanghai Medical University,Shanghai 200032)主编 Editor-in-chief张友会 Zhang Youhui(Cancer Institute,Chinese Academy of Medical Sciences,Beijing,100021)副主编 Associate Editor-in-chief崔正言 Cul Zhenyan(Department of Immunology,Shandong Academy of Medical Sciences,Jinan 250001)钱振超 Qian Zhenchao(Department of Patho-physiology,Dalian Medical University,Dalian 116027)何球藻 He Qiuzao(Department of Immunology,Shanghai Medical University,Shanghai 200032)董志伟 Dong Zhiwei(Cancer Institute,Chinese Academy of Medical Sciences,Beijing 100021)常务副主编 Managing Editor-in-chief