Leukemogenic Kras mutation reprograms multipotent progenitors to facilitate its spread through the hematopoietic...

Area of Science:

• Hematology
• Cancer Biology
• Stem Cell Biology

Background:

• Leukemia-driving mutations are hypothesized to originate in hematopoietic stem cells (HSCs).
• The precise mechanisms governing the spread and progression of these mutations within the hematopoietic system remain unclear.
• Understanding the early events following mutation acquisition is crucial for deciphering leukemia pathogenesis.

Purpose of the Study:

• To investigate the natural history and spread of oncogenic mutations within endogenous hematopoietic stem cells (HSCs) in vivo.
• To elucidate the role of multipotent progenitors (MPPs) in the expansion of leukemia-driving mutations.
• To explore therapeutic strategies targeting the early propagation of preleukemic cells.

Main Methods:

• Genetic induction of KrasG12D mutations in murine hematopoietic stem cells (HSCs).
• Tracking of mutant cell populations and their contribution to hematopoietic lineages in unmanipulated animals.
• Analysis of progenitor cell proliferation, self-renewal, and transcriptomic profiles.
• Investigating the role of osteopontin and CXCR4 signaling in mutant cell expansion.
• Evaluating the efficacy of therapeutic blockade of KRASG12D and CXCR4.

Main Results:

• The leukemogenic KrasG12D mutation, unlike Tet2 deletion, significantly accelerated HSC contribution to all blood lineages.
• KrasG12D-expressing multipotent progenitors (MPPs) exhibited increased proliferation and aberrant gene expression but lacked self-renewal capacity.
• Deletion of osteopontin and blockade of CXCR4 signaling attenuated the expansion of mutant progenitors.
• Therapeutic KRASG12D blockade reduced MPP expansion and their progeny, though it spared mutant HSCs.

Conclusions:

• Transforming mutations reprogram multipotent progenitors (MPPs), facilitating their own spread from hematopoietic stem cells (HSCs).
• This reprogramming establishes a preleukemic state through a two-component stem/progenitor circuit involving KrasG12D.
• Targeting the expansion of reprogrammed progenitors, rather than stem cells alone, may offer a viable therapeutic strategy.