| BackgroundChronic myeloid leukemia (CML) is a kind of chronic clonal myeloproliferativeneoplasms accompanied with Ph chromosome and (or) BCR-ABL fusion gene. Its clinicalcharacteristics include peripheral blood leukocytosis accompanied with immaturegranulocytes and splenomegaly. CML accounts for15%to20%of all leukemia, and mayoccur in all ages, while the median age for primary diagnosis was50to60years old, and maleto female patient ratio was1.4:1. The examinations on bone marrow smears, Ph chromosome,and BCR-ABL fusion gene are now commonly used in patients with CML for CML diagnosis,staging, therapeutical efficacy and prognosis. In recent years, researchers have discovered anew class of endogenous non-coding RNA with regulatory functions on gene expression, themicroRNA (miRNA). miRNAs have a wide variety of biological functions involving cellgrowth, development, apoptosis, differentiation, proliferation, and plays a vital role in theoccurrence and development of tumors. Recent studies have found that disorder of miRNAexpression plays an important role in the development of drug resistance in CML and otherprocesses.This study was aiming to further explore this mechanism and is expecting miRNAto become the indicator of diagnosis, treatment and prognosis of CML.miRNA is a class of important molecules that regulate gene expression with the sizeabout22nucleotides. There are two ways for miRNA to regulate target genes: on the onehand, it can inhibit target mRNA translation, on the other hand, it can mediate target mRNAdegradation. MiRNA bind to the target mRNA based on the complementary degree, which determines the specific mode of action. miRNA, cytoplasmic helicase, exonuclease, andendonuclease together integrates into the RNA-induced silencing complex RNA-inducedsilencing complex (RISC). When miRNA and its target mRNA are completely or almostcompletely paired, this complex can degrade the target mRNA. When the miRNA and thetarget mRNA, usually in the3’-UTR (untranslated region), cannot form completelycomplementary binding pair, the function of the ribosome is suppressed, thereby causing theinhibition of the translation of its target mRNA. Studies have shown that, miRNAs expressionis closely related to the occurrence of the development of CML, such as miR-203, miR-451,and miR-17. Awaring of the interaction among these three miRNAs in CML patients, wespeculate that they could potentially act as a kind of oncogenes or a tumor suppressor geneTherefore, in this study we analyzed the expression of miR-203, miR-451, and miR-17inbone marrow mononuclear cells of CML patients with different stages of disease, and theassociation of these miRNAs with BCR-ABL expression level in order to explore their role inthe diagnosis, staging, and therapeutical efficacy prediction.MethodsSubjectsA total of98cases of CML patients, including56cases of male patients,42cases offemale patients. Among them, there were35cases of newly diagnosed CML, and63cases ofrelapsed CML. By disease staging classification, patients in chronic phase (CML-CP) were45cases, accelerated phase (CML-AP)17cases, blastic phases (CML-BP)18cases, and CMLremission18cases. Categorized by BCR-ABL fusion gene, BCR-ABL-positive patients wereshown in80cases, and negative in18cases. Categorized by treatments, TKI treatment wasapplied to14cases, stem cell transplantation to7cases, and traditional chemotherapy to42cases. Categorized by therapeutical efficacy, ineffective treatment occurred in45cases ofdisease progression, while CML remission was achieved in18patients. Normal controlswere 20cases, including13males and7females, which were demonstrated by regular bonemarrow examination.Experimental methodsQuantitative real-time PCR was used to detect the expression levels of miR-203,miR-451, and miR-17, and simultaneous detection of BCR-ABL fusion gene expressionlevels. These data were analyzed in combination with the patient-related clinical data and itssignificance was proposed.Results1. Expression of miR-203in CML patientsIn newly diagnosed CML group, miR-203expression level (28.45±5.4) wassignificantly lower than that of the control group (151.69±32.15) and CML remission group(197.43±35.40), and the difference was statistically significant (P <0.05). The expressionlevels of miR-203did not show significant difference among CML-CP group (27.01±8.42)CML-BP group (27.41±8.33), and AP group (29.41±8.83)(P>0.05), but they weresignificantly lower than that of the control group and the remission group (P <0.05). Theexpression level of miR-203in progressed patients with relapse and ineffective treatmentresponse (21.40±7.17) was lower than that of the control group and remission group (P<0.05), but statistically was not significantly different from that of the newly diagnosed CMLgroup (28.45±5.4)(P <0.05).2. The expression of miRNA-451in CML patientsIn the newly diagnosed CML group, miR-451expression level was (19.45±6.72), andsignificantly lower than that of the control group (224.56±34.90) and CML remission group(211.76±39.89), and the difference was statistically significant (P <0.05). In CML-CP,CML-BP and CML-AP groups, the expression levels of miR-451was not statistically significant (P>0.05). The miR-451expression levels in CML-CP (27.01±8.42), CML-BP(19.98±7.71), CML-AP (19.97±7.50) group were not statistically different, but weresignificantly lower than that of the control group and the remission group (P <0.05). Inprogressed patients with relapse and ineffective treatment response, the expression level ofmiR-451(21.78±9.87) was lower than that of the normal control group and remission group,and the difference was statistically significant (P <0.05), but was not statistically significant(P>0.05) with the newly diagnosed CML group(19.45±6.72).3. The expression of miRNA-17in CML patientsIn the newly diagnosed CML group, miR-17expression level (137.10±31.27) wassignificantly higher than that in the control group (17.68±6.39) and the CML remissiongroup (21.09±38.36), and the difference was statistically significant (P <0.05). In CML-CPgroup, the expression level of miR-17was (156.10±35.71), and the expression levelincreased when patients achieved remission (P <0.05). In CML-AP group and BP group, theexpression levels of miR-17was significantly lower than that of the CML-CP group (P <0.05),while there was no significant difference between BP and AP group. In progressed patientswith relapse and ineffective treatment response group, the expression levels of miR-17decreased along with disease progression, and was significantly lower than newly diagnosedCML and CML-CP group (P <0.05). The expression level of miR-17in the remission groupwas significantly lower than that in newly diagnosed CML and CML-CP group (P <0.05).4. Association analysis between the expressions of miRNAs and BCR-ABL fusion geneThe expression levels of miR-203, miR-451in BCR-ABL-negative group weresignificantly higher than that in BCR-ABL-positive group and in the normal control, while theexpression levels of miR-17were significantly lower than that in the positive group. ThroughPearson product-moment correlation analysis, it was shown that the expression level ofmiR-203and BCR-ABL fusion gene was negatively correlated (r=-0.934, P=0.000);expression level of miR-451and BCR-ABL fusion gene was negatively correlated (r=-0.917, P=0.000); the expression level of miR-17in CML-CP group and the BCR-ABL fusion genelevels were positively correlated (r=0.803, P=0.000). Stepwise multiple regression analysisfound that the association of miR-203expression level with BCR-ABL level is the mostsignificant, and the coefficient of determination F=66.617, p≈.000<0.01. The regressionfunction y=94.8460.485x2(y, BCR-ABL; x2, miR-203) exhibited significantassociation between the expression of miR-203and BCR-ABL.5. Evaluating the significance of the miRNAs for CML diagnosis, staging, treatment andprognosisNo difference was found for miR-17expression levels between CML-BP group andCML-AP group, but the expression level of miR-17in CML-CP group was significantlyhigher than that in other groups (P <0.05). The expression level of miR-203and miR-451inremission group were significantly different with other groups (P <0.05), but the differencebetween CML-AP，CML-BP or CML-CP were not significant. These three kinds of miRNAexpression levels were significantly different between conventional chemotherapy group andTKI and HSCT group, but the expression level of these three miRNA level in TKI group werenot significantly different with HSCT.Conclusions1. The expression levels of miR-203, miR-451were negatively correlated withBCR-ABL expression levels. In the chronic phase, miR-17expression levels and BCR-ABLexpression levels were positively correlated. These data suggested that miR-203, miR-451,and miR-17may be the new biological markers for CML diagnosis and staging.2. miR-203, miR-451, and miR-17expression levels were associated with CMLoccurrence, development and prognosis, and could be an important reference for staging andprogression risk assessment.3. Further study on the biological effects of these miRNAs may provide a theoretical basis for molecular targeting therapy. |
PDF Full Text Request