Hedgehog (hh) signaling, a highly conserved developmental pathway, has been proven as an important pathway to maintain lsc function. the loss of hh pathway impairs the development of bcr-abl-induced chronic myeloid leukemia (cml) and depletes cml stem cells. therefore, it is intriguing to postulate that the aberrant acquisition of self-renewal property due to aberrant activation of hh signaling contributes to the cml progression. this highlights the necessity of inhibition of other targets besides bcr-abl, like hh signaling that regulate leukemic self-renewal, in order to inhibiting proliferation of bcr-abl-positive cd34+ lscs.
Primary cd34+ cells were isolated from six patients suffering cml in blast crisis phase using macs immunomagnetic separation system. overexpression of mir-324 was done by plenti-iii-egfp. expression levels of hh genes and mir-324-5p were measured by real-time pcr.
The present study revealed that overexpression of mir-324-5p led to down-regulation of smo and gli1, resulted in decreased cell proliferation in cml cd34+ cells. thus, smo and gli1 appears to be an essential target of mir-324-5p during pathogenesis of cml.
This study is the first evidence of the involvement of mir-324-5p-mediated regulation of hh signaling in pathophysiology of cml. our findings lead us to suggest that down-regulation of mir-324-5p may be a possible mechanism for unrestricted activation of the oncogenic hh pathway in cml; therefore, the restoration of mir-324-5p expression could be of benefit in inhibiting the proliferation capability of cd34+ cml cells that represent a potential source of relapse in patients suffering cml.