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Apaf-1 and caspase-9 do not act as tumor suppressors in myc-induced lymphomagenesis or mouse embryo fibroblast transformation.

Scott CL, Schuler M, Marsden VS, Egle A, Pellegrini M, Nesic D, Gerondakis S, Nutt SL, Green DR, Strasser A - J. Cell Biol. (2004)

Bottom Line: Based on experiments with cultured fibroblasts, the apoptosis regulators caspase-9 and Apaf-1 are hypothesized to function as tumor suppressors.Surprisingly, no differences were seen in rate, incidence, or severity of lymphoma with loss of Apaf-1 or caspase-9, and Apaf-1 was not a critical determinant of anticancer drug sensitivity of c-myc-induced lymphomas.Thus, Apaf-1 and caspase-9 do not suppress c-myc-induced lymphomagenesis and embryo fibroblast transformation.

View Article: PubMed Central - PubMed

Affiliation: The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia.

ABSTRACT
Based on experiments with cultured fibroblasts, the apoptosis regulators caspase-9 and Apaf-1 are hypothesized to function as tumor suppressors. To investigate their in vivo role in lymphomagenesis, an IgH enhancer-driven c-myc transgene was crossed onto Apaf-1(-/-) and caspase-9(-/-) mice. Due to perinatal lethality, Emu-myc transgenic Apaf-1(-/-) or caspase-9(-/-) fetal liver cells were used to reconstitute lethally irradiated recipient mice. Surprisingly, no differences were seen in rate, incidence, or severity of lymphoma with loss of Apaf-1 or caspase-9, and Apaf-1 was not a critical determinant of anticancer drug sensitivity of c-myc-induced lymphomas. Moreover, loss of Apaf-1 did not promote oncogene-induced transformation of mouse embryo fibroblasts. Thus, Apaf-1 and caspase-9 do not suppress c-myc-induced lymphomagenesis and embryo fibroblast transformation.

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Genotyping of lymphomas and lymphoma-derived cell lines. (A) Apaf-1 allele-specific PCR and (B) Western blot analysis of lymphomas and lymphoma cell lines. A small amount of Apaf-1 protein was detected in some Eμ-myc/Apaf-1−/− lymphoma samples, most likely due to contaminating recipient-derived stromal tissue, as no Apaf-1 protein was detected in the cell lines derived from these lymphomas.
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fig1: Genotyping of lymphomas and lymphoma-derived cell lines. (A) Apaf-1 allele-specific PCR and (B) Western blot analysis of lymphomas and lymphoma cell lines. A small amount of Apaf-1 protein was detected in some Eμ-myc/Apaf-1−/− lymphoma samples, most likely due to contaminating recipient-derived stromal tissue, as no Apaf-1 protein was detected in the cell lines derived from these lymphomas.

Mentions: Six cohorts of mice were reconstituted and followed: Eμ-myc/Apaf-1+/+, n = 60 mice for 44 wk (mean); Eμ-myc/Apaf-1+/−, n = 51 for 61 wk; Eμ-myc/Apaf-1−/−, n = 39 for 52 wk; Eμ-myc/caspase-9+/−, n = 34 for 44 wk; Eμ-myc/caspase-9−/−, n = 10 for 62 wk; and Eμ-myc/Eμ-bcl-2, n = 22 for 19 wk. Immunofluorescent staining with antibodies to Ly5.1 and Ly5.2 and FACS® analysis demonstrated that for 61 out of 66 recipient mice tested, reconstitution of the hemopoietic system was >80%. Surface immunostaining of tumor cells from Eμ-myc/Apaf-1+/+, Eμ-myc/Apaf-1−/−, and Eμ-myc/caspase-9−/− stem cell reconstituted mice confirmed that the majority were donor-derived pre–B cell (Ly5.2+B220+sIgM−) or B cell (Ly5.2+B220+sIgM+) lymphomas (Table SI, available at http://www.jcb.org/cgi/content/full/jcb.200310041/DC1). Lymphomas were transplantable into nonirradiated C57BL/6 recipient mice as follows: Eμ-myc /Apaf-1+/+, n = 7/7; Eμ-myc /Apaf-1+/−, n = 4/4; Eμ-myc /Apaf-1−/−, n = 8/8; and Eμ-myc / Eμ-bcl-2, n = 3/3. Apaf-1 genotype was confirmed by PCR, and lack of Apaf-1 protein expression was confirmed by Western blotting (Fig. 1, A and B).


Apaf-1 and caspase-9 do not act as tumor suppressors in myc-induced lymphomagenesis or mouse embryo fibroblast transformation.

Scott CL, Schuler M, Marsden VS, Egle A, Pellegrini M, Nesic D, Gerondakis S, Nutt SL, Green DR, Strasser A - J. Cell Biol. (2004)

Genotyping of lymphomas and lymphoma-derived cell lines. (A) Apaf-1 allele-specific PCR and (B) Western blot analysis of lymphomas and lymphoma cell lines. A small amount of Apaf-1 protein was detected in some Eμ-myc/Apaf-1−/− lymphoma samples, most likely due to contaminating recipient-derived stromal tissue, as no Apaf-1 protein was detected in the cell lines derived from these lymphomas.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171953&req=5

fig1: Genotyping of lymphomas and lymphoma-derived cell lines. (A) Apaf-1 allele-specific PCR and (B) Western blot analysis of lymphomas and lymphoma cell lines. A small amount of Apaf-1 protein was detected in some Eμ-myc/Apaf-1−/− lymphoma samples, most likely due to contaminating recipient-derived stromal tissue, as no Apaf-1 protein was detected in the cell lines derived from these lymphomas.
Mentions: Six cohorts of mice were reconstituted and followed: Eμ-myc/Apaf-1+/+, n = 60 mice for 44 wk (mean); Eμ-myc/Apaf-1+/−, n = 51 for 61 wk; Eμ-myc/Apaf-1−/−, n = 39 for 52 wk; Eμ-myc/caspase-9+/−, n = 34 for 44 wk; Eμ-myc/caspase-9−/−, n = 10 for 62 wk; and Eμ-myc/Eμ-bcl-2, n = 22 for 19 wk. Immunofluorescent staining with antibodies to Ly5.1 and Ly5.2 and FACS® analysis demonstrated that for 61 out of 66 recipient mice tested, reconstitution of the hemopoietic system was >80%. Surface immunostaining of tumor cells from Eμ-myc/Apaf-1+/+, Eμ-myc/Apaf-1−/−, and Eμ-myc/caspase-9−/− stem cell reconstituted mice confirmed that the majority were donor-derived pre–B cell (Ly5.2+B220+sIgM−) or B cell (Ly5.2+B220+sIgM+) lymphomas (Table SI, available at http://www.jcb.org/cgi/content/full/jcb.200310041/DC1). Lymphomas were transplantable into nonirradiated C57BL/6 recipient mice as follows: Eμ-myc /Apaf-1+/+, n = 7/7; Eμ-myc /Apaf-1+/−, n = 4/4; Eμ-myc /Apaf-1−/−, n = 8/8; and Eμ-myc / Eμ-bcl-2, n = 3/3. Apaf-1 genotype was confirmed by PCR, and lack of Apaf-1 protein expression was confirmed by Western blotting (Fig. 1, A and B).

Bottom Line: Based on experiments with cultured fibroblasts, the apoptosis regulators caspase-9 and Apaf-1 are hypothesized to function as tumor suppressors.Surprisingly, no differences were seen in rate, incidence, or severity of lymphoma with loss of Apaf-1 or caspase-9, and Apaf-1 was not a critical determinant of anticancer drug sensitivity of c-myc-induced lymphomas.Thus, Apaf-1 and caspase-9 do not suppress c-myc-induced lymphomagenesis and embryo fibroblast transformation.

View Article: PubMed Central - PubMed

Affiliation: The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia.

ABSTRACT
Based on experiments with cultured fibroblasts, the apoptosis regulators caspase-9 and Apaf-1 are hypothesized to function as tumor suppressors. To investigate their in vivo role in lymphomagenesis, an IgH enhancer-driven c-myc transgene was crossed onto Apaf-1(-/-) and caspase-9(-/-) mice. Due to perinatal lethality, Emu-myc transgenic Apaf-1(-/-) or caspase-9(-/-) fetal liver cells were used to reconstitute lethally irradiated recipient mice. Surprisingly, no differences were seen in rate, incidence, or severity of lymphoma with loss of Apaf-1 or caspase-9, and Apaf-1 was not a critical determinant of anticancer drug sensitivity of c-myc-induced lymphomas. Moreover, loss of Apaf-1 did not promote oncogene-induced transformation of mouse embryo fibroblasts. Thus, Apaf-1 and caspase-9 do not suppress c-myc-induced lymphomagenesis and embryo fibroblast transformation.

Show MeSH
Related in: MedlinePlus