| 1. |
- Eklund, Lena, 1969-, et al.
(författare)
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Regional mapping of suppressor loci for anchorage independence and tumorigenicity on human chromosome 9
- 2001
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Ingår i: Cancer Genetics and Cytogenetics. - 0165-4608 .- 1873-4456. ; 130:2, s. 118-126
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Tidskriftsartikel (refereegranskat)abstract
- By microcell-mediated chromosome transfer to the malignant Syrian hamster cell line BHK-191-5C, we previously identified two suppressor functions on human chromosome 9 (HSA9), one for anchorage independence and another for tumorigenicity. However, the precise chromosomal locations of these suppressor functions were not determined. The present study was undertaken to define the regional location of these suppressor loci using a panel of microcell hybrids containing structurally altered HSA9 with different deleted regions in the BHK-191-5C background. DNA derived from the cell hybrids was analyzed by PCR for verification of the presence of HSA9 genetic material by amplifying 62 microsatellite markers and 13 genes, covering the entire length of HSA9. Our deletion mapping data on anchorage independent and tumorigenic hybrids suggest that the suppressor function for anchorage independence is located in the region between 9q32 to 9qter. The suppressor for tumorigenicity may be located in one of three deleted regions on HSA9, the first one between the markers D9S162 and D9S1870, the second one between the markers D9S1868 and TIGRA002I21, and the third one between the markers D9S59 and D9S155.
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| 2. |
- Islam, Quamrul, 1952-, et al.
(författare)
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A new functional classification of tumor-suppressing genes and its therapeutic implications
- 2000
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Ingår i: Bioessays. - 0265-9247 .- 1521-1878. ; 22:3, s. 274-285
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Tidskriftsartikel (refereegranskat)abstract
- Cell fusion studies have demonstrated that malignancy can be suppressed by a single dose of malignancy suppressor genes (MSGs), indicating that malignancy is a recessive phenotype. Correspondingly, it is widely believed that mutational inactivation of both alleles of tumor suppressor genes (TSGs), in familial and sporadic tumors, is the formal proof of the recessive nature of malignancy. Evidence presented here, however, shows that unlike MSGs, identified solely through cell fusion studies with no gene of this class yet cloned, many well-known TSGs have gene dosage effects and inhibit cellular growth in vitro. Moreover, homozygous inactivation of a growth-inhibitory TSG (GITSG) is not directly correlated with malignancy. An alternative interpretation is provided for the loss of wild-type alleles of these genes in the tumors. It is concluded that the MSGs and the GITSGs do not belong to the same class of genes. The functional classification of tumor-suppressing genes has important implications for developing effective cancer therapies. (C) 2000 John Wiley and Sons, Inc.
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| 3. |
- Islam, Quamrul, 1952-, et al.
(författare)
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Epigenetic reprogramming of nonreplicating somatic cells for long-term proliferation by temporary cell-cell contact
- 2007
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Ingår i: Stem Cells and Development. - : Mary Ann Liebert Inc. - 1547-3287 .- 1557-8534. ; 16:2, s. 253-268
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Tidskriftsartikel (refereegranskat)abstract
- Embryonic stem (ES) cells are potential sources of tissue regeneration, however, transplanted ES cells produce tumors in the host tissues. In addition, transplantation between genetically unrelated individuals often results in graft rejection. Although the development of patient specific stem cell lines by somatic cell nuclear transfer (SCNT) represents a means of overcoming the problem of rejection, its human application has ethical dilemmas. Adult stem (AS) cells can also differentiate into specialized cells and may provide an alternative source of cells for human applications. In common with other somatic cells, AS cells have limited capacity for proliferation and cannot be produced in large quantities without genetic manipulation. We demonstrate here that nonreplicating mammalian cells can be reprogrammed for long-term proliferation by temporary cell-cell contact through co-culture of AS cells with the GM05267-derived F7 mouse cell line. Subsequent elimination of F7 cells from the co-culture allows proliferation of previously nonreplicating cells, colonies of which can be isolated to produce cell lines. We also demonstrate that the epigenetically reprogrammed AS cells, without the physical transfer of either nuclear or cytoplasmic material from other cells, are capable of long-term proliferation and able to relay signals to other nonreplicating cells to reinitiate proliferation with no addition of recombinant factors. The reported cell amplification procedure is methodologically simple and can be easily reproduced. This procedure allows the production of an unlimited number of cells from a limited number of AS cells, making them an ideal source of cells for applications involving autologous cell transplantation. © Mary Ann Liebert, Inc.
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| 4. |
- Islam, Quamrul, 1952-, et al.
(författare)
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Evidence for suppression of cellular growth in vitro and selection against the indigenous mouse X chromosome in A9 cell hybrids after microcell-modiated transfer of an X from other mammalian species
- 2000
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Ingår i: Cytogenetics and Cell Genetics. - 0301-0171 .- 1421-9816. ; 88:1-2, s. 110-113
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Tidskriftsartikel (refereegranskat)abstract
- Introduction of a human or Syrian hamster X chromosome (derived from BHK-191-5C cell hybrids) into tumorigenic mouse A9 cells via microcell fusion induced changes in cellular morphology and a retardation of cellular growth. The suppression of growth of the hybrids could be abolished, however, by daily changes of medium containing 20% serum. G-banding analysis showed the absence of a single, cytogenetically identifiable, indigenous X chromosome (marker Z) in two of four hybrid clones after an X chromosome was transferred from either hamster or human cells. All hybrids were tumorigenic when tested in nude mice. Together, these data suggest that the loss of the mouse X chromosome took place probably because of growth inhibitory effects imposed on hybrid cells due to the increase in X chromosome dosage. In addition, our results show a lack of association between the phenotype of cellular growth suppression in vitro and the phenotype of suppression of tumorigenicity in vivo. Copyright (C) 2000 S. Karger AG, Basel.
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| 5. |
- Islam, Quamrul, 1952-, et al.
(författare)
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Functional characterization of cell hybrids generated by induced fusion of primary porcine mesenchymal stem cells with an immortal murine cell line
- 2006
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Ingår i: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 326:1, s. 123-137
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Tidskriftsartikel (refereegranskat)abstract
- Bone marrow mesenchymal stem cells (MSC) integrate into various organs and contribute to the regeneration of diverse tissues. However, the mechanistic basis of the plasticity of MSC is not fully understood. The change of cell fate has been suggested to occur through cell fusion. We have generated hybrid cell lines by polyethylene-glycol-mediated cell fusion of primary porcine MSC with the immortal murine fibroblast cell line F7, a derivative of the GM05267 cell line. The hybrid cell lines display fibroblastic morphology and proliferate like immortal cells. They contain tetraploid to hexaploid porcine chromosomes accompanied by hypo-diploid murine chromosomes. Interestingly, many hybrid cell lines also express high levels of tissue-nonspecific alkaline phosphatase, which is considered to be a marker of undifferentiated embryonic stem cells. All tested hybrid cell lines retain osteogenic differentiation, a few of them also retain adipogenic potential, but none retain chondrogenic differentiation. Conditioned media from hybrid cells enhance the proliferation of both early-passage and late-passage porcine MSC, indicating that the hybrid cells secrete diffusible growth stimulatory factors. Murine F7 cells thus have the unique property of generating immortal cell hybrids containing unusually high numbers of chromosomes derived from normal cells. These hybrid cells can be employed in various studies to improve our understanding of regenerative biology. This is the first report, to our knowledge, describing the generation of experimentally induced cell hybrids by using normal primary MSC. © Springer-Verlag 2006.
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| 6. |
- Islam, Quamrul, 1952-, et al.
(författare)
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Generation of somatic cell hybrids for the production of biologically active factors that stimulate proliferation of other cells
- 2007
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Ingår i: Cell Proliferation. - : Wiley. - 0960-7722 .- 1365-2184. ; 40:1, s. 91-105
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Some normal somatic cells in culture divide a limited number of times before entering a non-dividing state called replicative senescence and fusion of normal cells with immortal cells claimed to produce hybrid cells of limited proliferation. We reinvestigated the proliferative capacity of hybrid cells between normal cell and immortal cell. Materials and Methods: Normal pig fibroblast cells and cells of immortal mouse fibroblast cell line F7, a derivative of GM05267, were fused by polyethylene glycol treatment and subsequently the fused cells were cultured in a selective medium containing hypoxanthine-aminopterin-thymidine in order to enrich the hybrid cells. The hybrid cells were then monitored for chromosome content and proliferation. Results: Cytogenetic analysis revealed that the hybrid cells contained polyploidy chromosomes derived from normal pig fibroblasts. These hybrid cells exhibit no sign of replicative senescence after more than 190 population doublings in vitro. Instead, these hybrid cells have an accelerated growth and proliferate even in the complete absence of glutamine. In addition, these hybrids produce biologically active factors in the conditioned media, which not only can accelerate their own proliferation but also can reinitiate mitotic activity in the senescent-like normal fibroblast cells. Conclusions: Our results question the validity of cellular senescence as a dominant trait. Additionally, the generation of hybrid cells using the specific mouse cell line can be applied to the generation of hybrids with other normal cell types and can be used to produce tissue-specific growth-factor(s) to extend the lifespan and/or improve the proliferation of various normal cells, including adult stem cells. © 2007 The Authors.
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| 7. |
- Islam, Quamrul, 1952-, et al.
(författare)
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Polyethylene glycol-mediated fusion between primary mouse mesenchymal stem cells and mouse fibroblasts generates hybrid cells with increased proliferation and altered differentiation
- 2006
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Ingår i: Stem Cells and Development. - : Mary Ann Liebert Inc. - 1547-3287 .- 1557-8534. ; 15:6, s. 905-919
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Tidskriftsartikel (refereegranskat)abstract
- Bone marrow-derived mesenchymal stem cells (MSCs) can differentiate into different cell lineages with the appropriate stimulation in vitro. Transplantation of MSCs in human and other animal models was found to repair tissues through the fusion of transplanted MSCs with indigenous cells. We have generated mouse-mouse hybrid cell lines in vitro by polyethylene glycol-mediated fusion of primary mouse MSCs with mouse fibroblasts to investigate the characteristics of hybrid cells, including their potentials for proliferation and differentiation. Similar to the parental MSCs, hybrid cells are positive for the cell-surface markers CD29, CD44, CD49e, and Sca-1, aed negative for Gr1, CD11b, CD13, CD18, CD31, CD43, CD45, CD49d, CD90.2, CD445M/B220, and CD117 markers. The hybrid cells also produce a high level of tissue nonspecific alkaline phosphatase compared to the parental cells. Conditioned medium of hybrid cells contain biologically active factors that are capable of stimulating proliferation of other cells. Although the parental MSCs can differentiate into adipogenic and osteogenic lineages, hybrid cells held disparate differentiation capacity. Hybrid cell lines in general have increased proliferative capacity than the primary MSCs. Our study demonstrates that proliferative hybrid cell lines can be generated in vitro by induced fusion of both im-mortal and primary somatic cells with primary MSCs. © Mary Ann Liebert, Inc.
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| 8. |
- Islam, Quamrul, 1952-, et al.
(författare)
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Suppressor genes for malignant and anchorage-independent phenotypes located on human chromosome 9 have no dosage effects
- 2000
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Ingår i: Cytogenetics and Cell Genetics. - 0301-0171 .- 1421-9816. ; 88:1-2, s. 103-109
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Tidskriftsartikel (refereegranskat)abstract
- We have previously shown that microcell-mediated transfer of a der(9)t(X,9) human chromosome (HSA), derived from human fibroblast strain GM0705, into the Syrian hamster cell line BHK-191-5C produced only near-tetraploid hybrids, although the recipient cell line contained a 1:1 ratio of near-diploid and near-tetraploid cells. However, the tumorigenicity and the anchorage independence could be suppressed in the near-tetraploid hybrids with one copy of the der(9)t(X,9) chromosome. The introduction of an HSA X chromosome did not suppress either of these phenotypes. We concluded that in addition to two suppressor genes, one for tumorigenicity and another for anchorage independence, HSA 9 might carry a third gene capable of inhibiting cellular growth in vitro, which had dosage effects. In the present study, keeping one copy of the der(9)t(X,9) chromosome, we have increased the hamster background chromosome number beyond hexaploid level by fusing two microcell-generated hybrid cell lines, where both malignant and anchorage-independent phenotypes were suppressed, with the parental malignant BHK-191-5C cell line. Tests with nude mice showed that hybrids containing one copy of the der(9)t(X,9) chromosome against the increased background of chromosomes of malignant parental origin were still suppressed for both phenotypes. These results suggest that the suppressor genes for malignancy and for anchorage independence have no dosage effects, in contrast to the suppressor gene(s) for cellular growth. Copyright (C) 2000 S. Karger AG, Basel.
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