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result(s) for
"Sadarangani, Anil"
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ADAR1 promotes malignant progenitor reprogramming in chronic myeloid leukemia
by
Jamieson, Catriona H. M.
,
Dao, Kim-Hien T.
,
Goldstein, Lawrence S. B.
in
adenosine deaminase
,
Adenosine Deaminase - genetics
,
Adenosine Deaminase - metabolism
2013
The molecular etiology of human progenitor reprogramming into self-renewing leukemia stem cells (LSC) has remained elusive. Although DNA sequencing has uncovered spliceosome gene mutations that promote alternative splicing and portend leukemic transformation, isoform diversity also may be generated by RNA editing mediated by adenosine deaminase acting on RNA (ADAR) enzymes that regulate stem cell maintenance. In this study, whole-transcriptome sequencing of normal, chronic phase, and serially transplantable blast crisis chronic myeloid leukemia (CML) progenitors revealed increased IFN-γ pathway gene expression in concert with BCR-ABL amplification, enhanced expression of the IFN-responsive ADAR1 p150 isoform, and a propensity for increased adenosine-to-inosine RNA editing during CML progression. Lentiviral overexpression experiments demonstrate that ADAR1 p150 promotes expression of the myeloid transcription factor PU.1 and induces malignant reprogramming of myeloid progenitors. Moreover, enforced ADAR1 p150 expression was associated with production of a misspliced form of GSK3β implicated in LSC self-renewal. Finally, functional serial transplantation and shRNA studies demonstrate that ADAR1 knockdown impaired in vivo self-renewal capacity of blast crisis CML progenitors. Together these data provide a compelling rationale for developing ADAR1-based LSC detection and eradication strategies.
Journal Article
Reversion to an embryonic alternative splicing program enhances leukemia stem cell self-renewal
by
Jamieson, Catriona H. M.
,
Mason, Cayla N.
,
Sadarangani, Anil
in
Adult
,
Alternative Splicing - genetics
,
Animals
2015
Formative research suggests that a human embryonic stem cell-specific alternative splicing gene regulatory network, which is repressed by Muscleblind-like (MBNL) RNA binding proteins, is involved in cell reprogramming. In this study, RNA sequencing, splice isoform-specific quantitative RT-PCR, lentiviral transduction, and in vivo humanized mouse model studies demonstrated that malignant reprogramming of progenitors into self-renewing blast crisis chronic myeloid leukemia stem cells (BC LSCs) was partially driven by decreased MBNL3. Lentiviral knockdown of MBNL3 resulted in reversion to an embryonic alternative splice isoform program typified by overexpression of CD44 transcript variant 3, containing variant exons 8–10, and BC LSC proliferation. Although isoform-specific lentiviral CD44v3 overexpression enhanced chronic phase chronic myeloid leukemia (CML) progenitor replating capacity, lentiviral shRNA knockdown abrogated these effects. Combined treatment with a humanized pan-CD44 monoclonal antibody and a breakpoint cluster region - ABL proto-oncogene 1, nonreceptor tyrosine kinase (BCR-ABL1) antagonist inhibited LSC maintenance in a niche-dependent manner. In summary, MBNL3 down-regulation–related reversion to an embryonic alternative splicing program, typified by CD44v3 overexpression, represents a previously unidentified mechanism governing malignant progenitor reprogramming in malignant microenvironments and provides a pivotal opportunity for selective BC LSC detection and therapeutic elimination.
Journal Article
GLI2 inhibition abrogates human leukemia stem cell dormancy
by
Reya, Tannishtha
,
Wall, Russell
,
Chun, Hye-Jung
in
Animals
,
Base Sequence
,
Biomedical and Life Sciences
2015
Background
Dormant leukemia stem cells (LSC) promote therapeutic resistance and leukemic progression as a result of unbridled activation of stem cell gene expression programs. Thus, we hypothesized that 1) deregulation of the hedgehog (Hh) stem cell self-renewal and cell cycle regulatory pathway would promote dormant human LSC generation and 2) that PF-04449913, a clinical antagonist of the GLI2 transcriptional activator, smoothened (SMO), would enhance dormant human LSC eradication.
Methods
To test these postulates, whole transcriptome RNA sequencing (RNA-seq), microarray, qRT-PCR, stromal co-culture, confocal fluorescence microscopic, nanoproteomic, serial transplantation and cell cycle analyses were performed on FACS purified normal, chronic phase (CP) chronic myeloid leukemia (CML), blast crisis (BC) phase CML progenitors with or without PF-04449913 treatment.
Results
Notably, RNA-seq analyses revealed that Hh pathway and cell cycle regulatory gene overexpression correlated with leukemic progression. While lentivirally enforced GLI2 expression enhanced leukemic progenitor dormancy in stromal co-cultures, this was not observed with a mutant GLI2 lacking a transactivation domain, suggesting that GLI2 expression prevented cell cycle transit. Selective SMO inhibition with PF-04449913 in humanized stromal co-cultures and LSC xenografts reduced downstream GLI2 protein and cell cycle regulatory gene expression. Moreover, SMO inhibition enhanced cell cycle transit and sensitized BC LSC to tyrosine kinase inhibition in vivo at doses that spare normal HSC.
Conclusion
In summary, while
GLI2
, forms part of a core HH pathway transcriptional regulatory network that promotes human myeloid leukemic progression and dormant LSC generation, selective inhibition with PF-04449913 reduces the dormant LSC burden thereby providing a strong rationale for clinical trials predicated on SMO inhibition in combination with TKIs or chemotherapeutic agents with the ultimate aim of obviating leukemic therapeutic resistance, persistence and progression.
Journal Article
NOTCH1 Signaling Promotes Human T-Cell Acute Lymphoblastic Leukemia Initiating Cell Regeneration in Supportive Niches
by
Jamieson, Catriona H. M.
,
Li, Kang
,
Wei, Ping
in
Activation
,
Acute lymphoblastic leukemia
,
Acute lymphocytic leukemia
2012
Leukemia initiating cells (LIC) contribute to therapeutic resistance through acquisition of mutations in signaling pathways, such as NOTCH1, that promote self-renewal and survival within supportive niches. Activating mutations in NOTCH1 occur commonly in T cell acute lymphoblastic leukemia (T-ALL) and have been implicated in therapeutic resistance. However, the cell type and context specific consequences of NOTCH1 activation, its role in human LIC regeneration, and sensitivity to NOTCH1 inhibition in hematopoietic microenvironments had not been elucidated.
We established humanized bioluminescent T-ALL LIC mouse models transplanted with pediatric T-ALL samples that were sequenced for NOTCH1 and other common T-ALL mutations. In this study, CD34(+) cells from NOTCH1(Mutated) T-ALL samples had higher leukemic engraftment and serial transplantation capacity than NOTCH1(Wild-type) CD34(+) cells in hematopoietic niches, suggesting that self-renewing LIC were enriched within the NOTCH1(Mutated) CD34(+) fraction. Humanized NOTCH1 monoclonal antibody treatment reduced LIC survival and self-renewal in NOTCH1(Mutated) T-ALL LIC-engrafted mice and resulted in depletion of CD34(+)CD2(+)CD7(+) cells that harbor serial transplantation capacity.
These results reveal a functional hierarchy within the LIC population based on NOTCH1 activation, which renders LIC susceptible to targeted NOTCH1 inhibition and highlights the utility of NOTCH1 antibody targeting as a key component of malignant stem cell eradication strategies.
Journal Article
TRAIL mediates apoptosis in cancerous but not normal primary cultured cells of the human reproductive tract
by
Lipkowitz, Stanley
,
Espinosa, Marisol
,
Villalón, Manuel
in
Apoptosis - drug effects
,
Apoptosis - genetics
,
Apoptosis - physiology
2007
Cancer of the reproductive tract encompasses malignancies of the uterine corpus, cervix, ovary, Fallopian tube, among others and accounts for 15% of female cancer mortalities. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) mediates apoptosis by binding to death receptors and offers a promising cancer treatment. The goal of this study was to investigate and characterize the effect of TRAIL in endometrial cancer cell lines and normal (non-cancerous) epithelial cells of endometrial origin. We also examined the effect of TRAIL in other primary cultured cancers and normal cells of the human female reproductive tract and evaluated if TRAIL mediated apoptosis correlated with death receptors and decoy receptors 1 and 2.Herein, we demonstrate that TRAIL at concentrations which kill cancerous cells, does not mediate apoptosis or alter cell viability in normal human endometrium, ovary, cervix or Fallopian tube. The partial inhibition by a caspase 9 inhibitor and the total inhibition by a caspase 8 inhibitor demonstrates the dependency on the extrinsic apoptotic pathway. The selective mortality does not correlate with the presence of death or decoy receptors. These results suggest that TRAIL may be an effective treatment for endometrial cancer and other female reproductive cancers, with minimal secondary effects on healthy tissue.
Journal Article
HAVE YOU EVER BEEN JEALOUS OF AISHWARYA?
Of course I am. This is the best phase of my life. I have no regret. I am scoccupied with work and family...
Newspaper Article
Mural makeover at Kala Ghoda
2006
Feb. 1--They're changing the guard at Kala Ghoda. Mumbai's art district is in the midst of getting a new horse mural, thanks to artist Baiju Parthan. The piece is commissioned by the Kala Ghoda association. As happy coincidence, the mural's unveiling coincides with the Times of India Kala Ghoda Fest commencing on February 4.
Newsletter
The buzz on celluloid
2005
You could attribute the critical acclaim for independent filmmaker Ashim Ahluwalia's latest documentary John and Jane to the fact that it's based on a sizzling topic right now -- call centres. So, while the rest of the world's heart burns at what's been touted as the best thing to happen to India (outsourcing+high income jobs = globalisation), Ahluwalia's film exposes the stark reality of the lives of call centre workers. What is surprising though is that even though the film has been very well received abroad, Ahluwalia doesn't think audiences are ready for it in India, except perhaps on the festival circuit.
Newsletter
Eat's all happenin' in Vegas
2005
Chef Hemant Oberoi, food critic Rashmi Uday Singh and Delhi's Jiggs Kalra will be flying off to Vegas to cook up a storm. While Jiggs Kalra will be giving a talk, Oberoi is going to be cooking a fancy Indian dinner. The million dollar question is -- will they only be cooking and eating or will they hit the slot machines too? \"I don't enjoy gambling but I love the ambience, I love to hang out there!\" says Rashmi, for whom this will be a first time trip to Las Vegas.
Newsletter