path823 mohan oct12paper

Slide1: 

Authors: Huntly, Brian J.P.a; Shigematsu, Hirokazub; Deguchi, Kenjia; Lee, Benjamin H.a; Mizuno, Shinichib; Duclos, Nickya; Rowan, Rebeccaa; Amaral, Soniaa; Curley, Davida; Williams, Ifor R.c; Akashi, Koichib; Gilliland, D. Garya Name: Reva Vidia Mohan Session Title: Nuclear Oncogenes and Gene Transcription Number of Session: 5 Date: October 12, 2006 MOZ-TIF2, but not BCR-ABL, confers properties of leukemic stem cells to committed murine hematopoietic progenitors

Malignant Cells in Cancer: Past vs. Present: 

Malignant Cells in Cancer: Past vs. Present Past Present - all cells have characteristic unlimited self-renewal - only subpopulations are capable of self-renewal Tumor

Supporting Evidence for Existence of CSCs: 

Supporting Evidence for Existence of CSCs Tumor Studies - Functional Heterogeneity - Serial Transplantation and Replating demonstrate stem cell characteristics Hematopoietic Malignancies - such as acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) - similar tests were done using human malignancies (transplanted in mice)

How do CSCs Originate?: 

How do CSCs Originate? Self Renewing Stem Cell Progenitor Lymphoid Progenitor Myeloid Progenitor Mature Blood Cells B cells and T cells Hematopoiesis

Evidence of Origin At…: 

Evidence of Origin At… 1) Stem Cell Transformation increase number of cell divisions Already possess the “machinery” phenotypic similarities (surface markers, levels of telomerases) Same chromosomal abnormality detected in cells throughout the lineage (e.g. CML)

Evidence of Origin At…: 

Evidence of Origin At… Committed Progenitor Transformation Some leukemias have different phenotypes but similar characteristic molecular abnormality MLL-ENL and committed myeloid progenitors (CMP)

About MOZ-TIF2 (MT): 

About MOZ-TIF2 (MT) Fusion oncogene formed by the inv(8)(p11q13) and is associated with AML MOZ Belongs to family of histone acetyltransferases Suggested function, transcriptional regulator because of histone acetyltransferase activity TIF2 - Nuclear receptor transcriptional coactivator - CBP binds the CBP interaction domain (CID) of TIF2 and it associates with nuclear receptors in ligand-dependent manner to stimulate gene expression (1) (1) (1) (1) Deguchi, K., Ayton, P., Carapeti, M., Kutok, J., Synder, C., Williams, I., Cross, N., Glass, C., and Gilliland, D. (2003) MOZ-TIF2- induced acute myeloid leukemia requires the MOZ nucleosome binding motif and TIF2-mediated recruitment of CBP. Cancer Cell. 3, 259-271.

About BCR-ABL (BA): 

About BCR-ABL (BA) - Oncogene resulting from t(9;22) - (q34;q11) BCR encodes serine and threonine kinase ABL encodes tyrosine kinase Both activate transcriptional factors (2) Deininger, M., Goldman, J., and Melo, J. (2000). The molecular biology of chronic myeloid leukemia. Blood 57, 1068-1073

Hypothesis: 

Hypothesis Are all oncogenes associated with leukemia able to confer the self-renewal capabilities to committed progenitor cells, which otherwise cannot self renew? Does transformation take place at the level of the CMP or GMP? Do these fusion oncogenes induce leukemia on their own or in concert with retroviral integration?

Outline of Study: 

Outline of Study Isolate progenitor cells using multi-parameter flow cytometry Transformed cells with either MOZ-TIF2 or BCR-ABL oncogenes using retroviral vectors Analyzed the transformed cells in vitro and in vivo Compared results to hematopoietic stem cells (HSCs) and whole bone marrow (WBM) transduced with the same fusion oncogenes

Results : 

Results 1) In vitro, MT, not BA confers self-renewal properties to the myeloid progenitors (3) Huntly, Brian J.P.a; Shigematsu, Hirokazub; Deguchi, Kenjia; Lee, Benjamin H.a; Mizuno, Shinichib; Duclos, Nickya; Rowan, Rebeccaa; Amaral, Soniaa; Curley, Davida; Williams, Ifor R.c; Akashi, Koichib; Gilliland, D. Garya (2004). MOZ-TIF2, but not BCR-ABL, confers properties of keukemic stem cells to committed murine hematopoietic progenitors. Cancer Cell 6, 587-596.

Results : 

Results MT-transduced cells, after serial replating induced AML in mice (3) Huntly, Brian J.P.a; Shigematsu, Hirokazub; Deguchi, Kenjia; Lee, Benjamin H.a; Mizuno, Shinichib; Duclos, Nickya; Rowan, Rebeccaa; Amaral, Soniaa; Curley, Davida; Williams, Ifor R.c; Akashi, Koichib; Gilliland, D. Garya (2004). MOZ-TIF2, but not BCR-ABL, confers properties of keukemic stem cells to committed murine hematopoietic progenitors. Cancer Cell 6, 587-596.

Results : 

Results 3) In vivo, MT-transduced CMP and GMP caused AML in mice (3) Huntly, Brian J.P.a; Shigematsu, Hirokazub; Deguchi, Kenjia; Lee, Benjamin H.a; Mizuno, Shinichib; Duclos, Nickya; Rowan, Rebeccaa; Amaral, Soniaa; Curley, Davida; Williams, Ifor R.c; Akashi, Koichib; Gilliland, D. Garya (2004). MOZ-TIF2, but not BCR-ABL, confers properties of keukemic stem cells to committed murine hematopoietic progenitors. Cancer Cell 6, 587-596.

Results : 

Results 4) Self-renewal capabilities further tested by transplantion of MT-transduced cells from primary to secondary recipient (threshold amount required) (3) Huntly, Brian J.P.a; Shigematsu, Hirokazub; Deguchi, Kenjia; Lee, Benjamin H.a; Mizuno, Shinichib; Duclos, Nickya; Rowan, Rebeccaa; Amaral, Soniaa; Curley, Davida; Williams, Ifor R.c; Akashi, Koichib; Gilliland, D. Garya (2004). MOZ-TIF2, but not BCR-ABL, confers properties of keukemic stem cells to committed murine hematopoietic progenitors. Cancer Cell 6, 587-596.

Results: 

Results 5) The domains required for self-renewal are the same as those required for leukemia transformation

Results: 

Results HSC (PB = peripheral blood, SM = submandibular gland) 6) Indistinguishable morphologies between different MT- transduced cells (3) Huntly, Brian J.P.a; Shigematsu, Hirokazub; Deguchi, Kenjia; Lee, Benjamin H.a; Mizuno, Shinichib; Duclos, Nickya; Rowan, Rebeccaa; Amaral, Soniaa; Curley, Davida; Williams, Ifor R.c; Akashi, Koichib; Gilliland, D. Garya (2004). MOZ-TIF2, but not BCR-ABL, confers properties of keukemic stem cells to committed murine hematopoietic progenitors. Cancer Cell 6, 587-596.

Results: 

Results HSC Similar expression of surface phenotypes regardless of initial cell population transduced with MT FACS analysis shows that cells with SC properties lies downstream of GMP (3) Huntly, Brian J.P.a; Shigematsu, Hirokazub; Deguchi, Kenjia; Lee, Benjamin H.a; Mizuno, Shinichib; Duclos, Nickya; Rowan, Rebeccaa; Amaral, Soniaa; Curley, Davida; Williams, Ifor R.c; Akashi, Koichib; Gilliland, D. Garya (2004). MOZ-TIF2, but not BCR-ABL, confers properties of keukemic stem cells to committed murine hematopoietic progenitors. Cancer Cell 6, 587-596.

Significance of Study: 

Significance of Study Since it was shown that certain fusion oncogenes can confer leukemic SC properties to committed progenitors, this provides tools for identifying cellular programs that result in self-renewal properties With further research, characterizing these programs could lead to targets where newer and better therapeutic intervention could take place 3) How BA and MT confer leukemic properties are not fully understood however, it is clear that oncogenes function in different ways to induce leukemia

Conclusion: 

Conclusion Not all oncogenes are capable of conferring self-renewal properties Transformation can occur at SC level or further down however, the population that has stem cell properties lies downstream of GMP Retroviral insertion is not enough to confer transformation

Clinical Implications: 

Clinical Implications Manipulate to use for beneficial purpose such as tissue regeneration By targeting these CSCs, can prevent relapse of disease

??? Questions ???: 

??? Questions ??? Why is imatinib not greatly effective in curing CML?? (2 reasons, please) Is it possible for patients with CML to develop AML? Why or why not? Is it possible for the reverse? Why or why not? If a form of leukemia clearly demonstrates transformation at the stem cell level, yet certain lineages are affected, how can this observation be explained?