Quantitative proteomics and its application in studying the functions of microRNA-155 in diffuse large B-cell lymphona.

摘要

Diffuse large B-cell lymphoma (DLBCL) is the most common form of human B-cell lymphomas and has variable clinical presentation. Abnormal microRNA-155 (miR-155) expression has been implicated in the pathogenesis of DLBCL. However, comprehensive evaluations of this microRNA in DLBCL malignancy are still limited.;In this study, a novel software tool, termed Uniquant, was developed to investigate the protein expression proflies in B-cell lymphoma cells. Performance of UNiquant was compared to MaxQuant and Mascot Distiller, which are the two most commonly used tools in this field. UNiquant showed a complementary coverage of quantified proteins with other programs when analyzing the same proteome datasets. Moreover, UNiquant showed superior ability to quantify proteins with different heavy/light ratios, and provide more accurate quantification results.;Second, proteomics technique with UNiquant was used to study how miR-155 effected on protein production in DLBCL cells. We identified not only the known targets of miR-155, such as SHIP1 and WEE1, but also a novel target, PIK3R1 (p85α, a regulatory subunit of PI3K). Direct binding between p85α 3'UTR and miR-155 was validated and significant repression of the luciferase reporter activity was demonstrated. Functional study indicated that overexpression of miR-155 upregulated AKT phosphorylation and increased DLBCL cell viability, while repression of miR-155 repressed AKT phosphorylation and decreased cell viability.;Third, the relationship between miR-155 and JAK/STAT3 signaling, another key pathway in DLBCL, was investigated. We showed that miR-155 expression and phosphorylation level of STAT3 are two independent prognostic factors related to worse survival, in DLBCL patients. More importantly, high expression of miR-155 was also observed in the STAT3 activated cases, which suggested coactivations of these two factors. We showed that STAT3 activation in DLBCL directly increased BIC and miR-155 expression in vitro in a time-dependent manner. Moreover, overexpression of miR-155 in DLBCL cells also up-regulated STAT3 activation by repressing SOCS1.;In summary, a software tool for quantitative proteomics was developed to investigate the impacts of miR-155 in DLBCL. Our study revealed novel targets of miR-155 biology. MiR-155 activation in DLBCL enhaced oncogenic PI3K/AKT pathway, and cross-talked between miR-155 and JAK/STAT3 pathway which consist a positive feedback regulation in the DLBCL malignancy.