Lnc SMAD5-AS1 as ceRNA inhibit proliferation of diffuse large B cell lymphoma via Wnt/ß-catenin pathway by sponging miR-135b-5p to elevate expression of APC.

Diffuse large B cell lymphoma (DLBCL) is a common and fatal hematological malignancy. Long noncoding RNAs (lncRNAs) have emerged as crucial biomarkers and regulators in many cancers. Novel lncRNA biomarker in DLBCL needs to be investigated badly, as well as its function and molecular mechanism. To further explore, microarray analysis was performed to identify the differentially expressed lncRNAs in DLBCL tissues. To investigate the biological functions of SMAD5-AS1, we performed gain- and loss-of-function experiments in vitro and in vivo. Furthermore, bioinformatics analysis, dual-luciferase reporter assays, Argonaute 2-RNA immunoprecipitation (AGO2-RIP), RNA pull-down assay, quantitative PCR arrays, western blot assay, TOPFlash/FOPFlash reporter assay, and rescue experiments were conducted to explore the underlying mechanisms of competitive endogenous RNAs (ceRNAs). We found that SMAD5-AS1 was down-regulated in DLBCL tissues and cell lines. Functionally, SMAD5-AS1 downregulation promoted cell proliferation in vitro and in vivo, whereas SMAD5-AS1 overexpression could lead to the opposite effects in vitro and in vivo. Bioinformatics analysis and luciferase assays revealed that miR-135b-5p was a direct target of SMAD5-AS1, which was validated by dual-luciferase reporter assays, AGO2-RIP, RNA pull-down assay, and rescue experiments. Also, dual-luciferase reporter assays and rescue experiments demonstrated that miR-135b-5p targeted the adenomatous polyposis coli (APC) gene directly. SMAD5-AS1/miR-135b-5p inhibits the cell proliferation via inactivating the classic Wnt/ß-catenin pathway in the form of APC dependency. Our results indicated that SMAD5-AS1 inhibits DLBCL proliferation by sponging miR-135b-5p to up-regulate APC expression and inactivate classic Wnt/ß-catenin pathway, suggesting that SMAD5-AS1 may act as a potential biomarker and therapeutic target for DLBCL.

The lower peripheral blood lymphocyte/monocyte ratio assessed during routine follow-up after standard first-line chemotherapy is a risk factor for predicting relapse in patients with diffuse large B-cell lymphoma.

A specific predictor during routine follow-up to ascertain risk for relapse after standard first-line chemotherapy in non-Hodgkin's lymphoma (NHL) has not been identified, although blood counts, lactate dehydrogenase (LDH) and imaging studies, such as computed tomography (CT) scans or positron emission tomography, have been recommended. Therefore, we studied the absolute lymphocyte count/absolute monocyte count ratio (ALC/AMC ratio) as a marker of poststandard first-line chemotherapy for predicting relapse in patients with diffuse large B-cell lymphoma (DLBCL). 220 consecutive DLBCL patients, originally diagnosed, treated with CHOP or R-CHOP and followed up at two institutions. ALC/AMC ratio was obtained at the time of confirmed relapse or last follow-up. Patients at the time of confirmed relapse (n = 163) had a lower ALC/AMC ratio compared with those at last follow-up (n = 57) (P < 0.001). ALC/AMC ratio at the time of confirmed relapse was a strong predictor for relapse with an area under the curve = 0.813 (P < 0.001). The sensitivity and specificity for ALC/AMC ratio at the time of confirmed relapse or at last follow-up were 68.1% and 87.7%, respectively, and the relative risk of relapse with an ALC/AMC ratio < 2.8 at the time of confirmed relapse or at last follow-up was 1.845 with an odds ratio of 15.247 (95% cumulative incidence: 6.473-35.916) after CHOP or R-CHOP in DLBCL. Patients with an ALC/AMC ratio (< 2.8) had a higher cumulative hazard rate of relapse compared with an ALC/AMC ratio (≥2.8) (P < 0.001). This study suggests that the lower ALC/AMC ratio can be used as a marker to assess risk of DLBCL relapse during routine follow-up after standard first-line chemotherapy.