Retroviral insertional mutagenesis identifies RUNX genes involved in chronic myeloid leukemia disease persistence under imatinib treatment

Abstract

The kinase inhibitor imatinib mesylate targeting the oncoprotein Bcr-Abl has revolutionized the treatment of chronic myeloid leukemia (CML). However, even though imatinib successfully controls the leukemia in chronic phase, it seems not to be able to cure the disease, potentially necessitating lifelong treatment with the inhibitor under constant risk of relapse. On a molecular level, the cause of disease persistence is not well understood. Initial studies implied that innate features of primitive progenitor cancer stem cells may be responsible for the phenomenon. Here, we describe an assay using retroviral insertional mutagenesis (RIM) to identify genes contributing to disease persistence in vivo.

RUNX3 is multifunctional in carcinogenesis of multiple solid tumors

“…EMT induction of transformed mammary epithelial cells leads to enrichment of cancer stem cells . Together with the report that increased RUNX3 expression is associated with cancer persistence in CML (Miething et al, 2007), it may be that RUNX3 is involved in cancer stem cell growth through modulation of EMT processes. Moreover, these findings point to the possibility that RUNX3 not only functions as a tumor suppressor during early tumor development, but may affect late stages of cancer progression.…”

“…As the only Runx protein expressed in this lymphoma, Runx3 thus seems to synergize with MYC oncogene to promote lymphomagenesis (Stewart et al, 2002). Miething et al (2007) further explored RUNX3's cancer function in leukemia when they incorporated a drug used for treatment of Bcr-Abl-expressing leukemia, imatinib, in their retroviral mutagenesis screen-they showed that insertion of a retroviral element in the vicinity of the RUNX3 promoter results in elevated RUNX3, which in turn led to increased resistance to imatinib-induced apoptosis and thus chronic myeloid leukemia (Miething et al, 2007). Runx3 was also identified as a cancerassociated gene by Sleeping Beauty transposable elements-transposon integration at the 5 0 position of the RUNX3 gene was associated with T-cell lymphoma (Dupuy et al, 2005) and prostate cancer (Rahrmann et al, 2009 Altogether, these findings suggest that while RUNX3 inactivation is a major determinant of cancer pathogenesis (see Table 1) and clinical outcome in many cancer types, in certain tumor types, overexpression of RUNX3 is oncogenic.…”

“…RUNX3 also has an oncogenic function in head and neck squamous cell carcinoma in which RUNX3 expression was correlated with enhanced cell proliferation and malignancy (Tsunematsu et al, 2009). Interestingly, ectopic RUNX3 expression inhibited chemotherapeutic drug adriamycin-induced apoptosis in head and neck squamous cell carcinoma cells, reminiscent of the RUNX3-induced resistance to imatinib-induced apoptosis in chronic myeloid leukemia (Miething et al, 2007;Tsunematsu et al, 2009). Thus, although RUNX3 is more commonly observed to suppress tumor formation, it has a dualistic function in cancer-whether it acts as tumor suppressor or oncogene is cell context dependent.…”

In vitro-established alloantigen-specific CD8+ CTLs mediate graft-versus-tumor activity in the absence of graft-versus-host disease

“…As BMT is a curative therapy for leukemias, the anti-tumor effect of CTLs was tested on the growth of Bcr-Abl-transformed B-ALL cells established by transformation of BM with MSCV MIG-p185 Bcr-Abl/GFPexpressing retroviral construct. 15 The Figure 7). Slightly elevated score levels in mice transplanted with TCD BM plus CTLs and L125 indicated tumor-dependent weight loss and fur ruffling.…”

A deep-sequencing study of chronic myeloid leukemia patients in blast crisis (BC-CML) detects mutations in 76.9% of cases

“…As only 4/13 of cases with mutated RUNX1 were concomitantly mutated in BCR-ABL (Figure 1), we suggest that abnormalities in RUNX1 have an independent role in tyrosine kinase inhibitor resistance and may contribute to treatment failure. 1,8 Figure 1 Frequencies and distribution of mutations. Frequencies are given for molecular mutations in RUNX1, ASXL1, IKZF1, WT1, TET2, IDH1, NRAS, KRAS, CBL and TP53.…”