Michael Fernandez

MicroRNA fingerprints identify miR-150 as a plasma prognostic marker in patients with sepsis

BACKGROUND The physiopathology of sepsis continues to be poorly understood, and despite recent advances in its management, sepsis is still a life-threatening condition with a poor outcome. If new diagnostic markers related to sepsis pathogenesis will be identified, new specific therapies might be developed and mortality reduced. Small regulatory non-coding RNAs, microRNAs (miRNAs), were recently linked to various diseases; the aim of our prospective study was to identify miRNAs that can differentiate patients with early-stage sepsis from healthy controls and to determine if miRNA levels correlate with the severity assessed by the Sequential Organ Failure Assessment (SOFA) score. METHODOLOGY/PRINCIPAL FINDINGS By using genome-wide miRNA profiling by microarray in peripheral blood leukocytes, we found that miR-150, miR-182, miR-342-5p, and miR-486 expression profiles differentiated sepsis patients from healthy controls. We also proved by quantitative reverse transcription-polymerase chain reaction that miR-150 levels were significantly reduced in plasma samples of sepsis patients and correlated with the level of disease severity measured by the SOFA score, but were independent of the white blood counts (WBC). We found that plasma levels of tumor necrosis factor alpha, interleukin-10, and interleukin-18, all genes with sequence complementarity to miR-150, were negatively correlated with the plasma levels of this miRNA. Furthermore, we identified that the plasma levels ratio for miR-150/interleukin-18 can be used for assessing the severity of the sepsis. CONCLUSIONS/SIGNIFICANCE We propose that miR-150 levels in both leukocytes and plasma correlate with the aggressiveness of sepsis and can be used as a marker of early sepsis. Furthermore, we envision miR-150 restoration as a future therapeutic option in sepsis patients.

Circulating microRNAs let-7a and miR-16 predict progression-free survival and overall survival in patients with myelodysplastic syndrome

Circulating microRNAs (miRNAs) are potential biomarkers for cancer. We examined plasma levels of 2 miRNAs, let-7a and miR-16, in 50 patients with myelodysplastic syndrome (MDS) and 76 healthy persons using quantitative real-time PCR. Circulating levels of both miRNAs were similar among healthy controls but were significantly lower in MDS patients (P = .001 and P < .001, respectively). The distributions of these 2 miRNA levels were bimodal in MDS patients, and these levels were significantly associated with their progression-free survival and overall survival (both P < .001 for let-7a; P < .001 and P = .001 for miR-16). This association persisted even after patients were stratified according to the International Prognostic Scoring System. Multivariate analysis revealed that let-7a level was a strong independent predictor for overall survival in this patient cohort. These findings suggest that let-7a and miR-16 plasma levels can serve as noninvasive prognostic markers in MDS patients.

Loss of SHIP-1 protein expression in high-risk myelodysplastic syndromes is associated with miR-210 and miR-155

The myelodysplastic syndromes (MDSs) comprise a group of disorders characterized by multistage progression from cytopenias to acute myeloid leukemia (AML). They display exaggerated apoptosis in early stages, but lose this behavior during evolution to AML. The molecular basis for loss of apoptosis is unknown. To investigate this critical event, we analyzed phosphatidylinositol (PI) 3′kinase signaling, implicated as a critical pathway of cell survival control in epithelial and hematological malignancies. PI 3′kinase activates Akt through its production of 3′ phosphoinositides. In turn, the phosphoinositides are dephosphorylated by two lipid phosphatases, PTEN and SHIP-1, in myeloid cells. We studied primary MDS-enriched bone marrow cells and bone marrow sections by western blotting, immunohistochemistry, immunocytochemistry and quantitative PCR for components of the SHIP/PTEN/PI 3′kinase signaling circuit. We reported constitutively activated Akt, variable levels of PTEN and uniformly decreased SHIP-1 expression in MDS progenitor cells. Overexpression of SHIP-1, but not the phosphatase-deficient form, inhibited myeloid leukemic growth. Levels of microRNA (miR)-210 and miR-155 transcripts, which target SHIP-1, were increased in CD34+ MDS cells compared with their normal counterparts. Direct binding of miR-210 to the 3′ untranslated region of SHIP-1 was confirmed by luciferase reporter assay. Transfection of a myeloid cell line with miR-210 resulted in loss of SHIP-1 protein expression. These data suggest that miR-155 and miR-210/SHIP-1/Akt pathways could serve as clinical biomarkers for disease progression, and that miR-155 and miR-210 might serve as novel therapeutic targets in MDS.

HDM4 (HDMX) is widely expressed in adult pre-B acute lymphoblastic leukemia and is a potential therapeutic target

Human homolog of murine double minute 2 (HDM2) and HDM4 (or HDMX) are negative regulators of p53. HDM4 has not been assessed in precursor B (pre-B) lymphoblastic leukemia (ALL). We examined bone marrow samples obtained at time of diagnosis from 55 adults with pre-B ALL. A tissue microarray composed of 2 cores per specimen was constructed and immunohistochemical techniques were used to assess HDM4, HDM2, p53, and p21. HDM4 was expressed in 39 of 49 (80%) cases. HDM2 was expressed in 14 of 54 (26%). All HDM2-positive cases were also positive for HDM4 (P<0.05). We confirmed expression of HDM4 and HDM4 variants by Western blotting and sequencing of reverse transcription-polymerase chain reaction products in a subset of ALL tumors. Results were correlated with the presence of the Philadelphia chromosome (Ph). p53 (P<0.05) and p21 (P<0.001) were expressed significantly more often in Ph+ pre-B ALL. HDM4 and HDM2 showed no correlation with Ph status. HDM4 expression in most cases of adult pre-B ALL suggests that HDM4 is a potential therapeutic target.

Aurora-A kinase nuclear expression in chronic lymphocytic leukemia

Aurora-A kinase is a cell-cycle-regulating kinase required for chromosomal segregation. Overexpression of Aurora-A kinase has been shown to correlate with tumor proliferation and chromosomal instability. We investigated Aurora-A kinase expression in peripheral blood and bone marrow of 47 chronic lymphocytic leukemia patients and 20 age-matched hematologically healthy subjects. Western blot analysis showed significantly higher Aurora-A levels in chronic lymphocytic leukemia (42 of 47) compared with lymphocytes of healthy subjects. However, Aurora-A mRNA expression in three chronic lymphocytic leukemia patients was similar to or lower than that of healthy control subjects. In 28 of 42 chronic lymphocytic leukemia patients with elevated Aurora-A kinase expression, one or more chromosomal abnormalities were detected, including trisomy 12 in 9 patients and deletion of the ataxia telangiectasia-mutated gene in 9 patients. Aurora-A was also detected in all (100%) chronic lymphocytic leukemia cases by immunohistochemistry, with a nuclear staining pattern. The larger prolymphocytes and paraimmunoblasts showed stronger Aurora-A kinase expression than did small lymphocytes. In contrast, normal bone marrow reactive lymphocytes were negative for Aurora-A with positive histiocytes and immature myeloid cells. Immunostaining for acetylated histone H3 showed a nuclear pattern in all 38 chronic lymphocytic leukemia cases and double labeling showed coexpression of acetylated histone H3 and Aurora-A. In summary, Aurora-A kinase is overexpressed in chronic lymphocytic leukemia cells. The expression of acetylated histone H3 suggests that Aurora-A kinase may be active (functional). Thus, Aurora-A kinase overexpression in chronic lymphocytic leukemia may be involved in the genesis of chromosomal abnormalities and is a potential target for therapeutic intervention.

Over-Expression of CYP2E1 mRNA and Protein: Implications of Xenobiotic Induced Damage in Patients with De Novo Acute Myeloid Leukemia with inv(16)(p13.1q22); CBFβ-MYH11

Environmental exposure to benzene occurs through cigarette smoke, unleaded gasoline and certain types of plastic. Benzene is converted to hematotoxic metabolites by the hepatic phase-I enzyme CYP2E1, and these metabolites are detoxified by the phase-II enzyme NQO1. The genes encoding these enzymes are highly polymorphic and studies of these polymorphisms have shown different pathogenic and prognostic features in various hematological malignancies. The potential role of different cytochrome p450 metabolizing enzymes in the pathogenesis of acute myeloid leukemia (AML) in an area of active interest. In this study, we demonstrate aberrant CYP2E1 mRNA over-expression by quantitative real-time polymerase chain reaction in 11 cases of de novo AML with inv(16); CBFβ-MYH11. CYP2E1 mRNA levels correlated with CBFβ-MYH11 transcript levels and with bone marrow blast counts in all cases. CYP2E1 over-expression correlated positively with NQO1 mRNA levels (R2 = 0.934, n = 7). By immunohistochemistry, CYP2E1 protein was more frequently expressed in AML with inv(16) compared with other types of AML (p < 0.001). We obtained serial bone marrow samples from two patients with AML with inv(16) before and after treatment. CYP2E1 mRNA expression levels decreased in parallel with CBFβ-MYH11 transcript levels and blast counts following chemotherapy. In contrast, CYP1A2 transcript levels did not change in either patient. This is the first study to demonstrate concurrent over-expression of CYP2E1 and NQO1 mRNA in AML with inv(16). These findings also suggest that a balance between CYP2E1 and NQO1 may be important in the pathogenesis of AML with inv(16).