Diffuse large B cell lymphoma (DLBCL) is the most common pathological subtype of non-Hodgkin lymphoma (NHL) and is the most common type of adult lymphoma. Due to the poor prognosis of relapsed/refractory DLBCL, new drug targets and therapeutic methods are urgently needed. We investigated the expression of programmed death ligand 1 (PD-L1) and 3-monooxygenase/tryptophan 5-monooxygenase activating protein zeta (14-3-3ζ or YWHAZ) in patients with DLBCL. The purpose was to verify the expression levels of YWHAZ and PD-L1 and their relationships with the prognosis of DLBCL and to lay a foundation for further study on the role of YWHAZ and PD-L1 in DLBCL. Immunohistochemistry was used in 140 patients with DLBCL to test protein expression levels of YWHAZ and PD-L1. All patients were followed up in the hospital or by telephone or via WeChat. The positive expression rate of YWHAZ was 62.14% (87/140). The expression was negatively correlated with the positive expression of BAD ( r = − 0.177 , P = 0.036 ) and positively correlated with the positive expression of BCL-2 ( r = 0.180 , P = 0.033 ). When the cut-off value for PD-L1 was established at 5%, 10%, 15%, and 20%, the corresponding positive expression rates of PD-L1 were 79.66% (94/118), 51.69% (61/118), 40.68% (48/118), and 36.44% (43/118). YWHAZ significantly affected the OS of DLBCL ( P ≤ 0.001 ). The prognosis of the patients was related to the positive expression of PD-L1 when the cut-off value of PD-L1 was 5% ( P = 0.033 ). However, positive expression of PD-L1 was not associated with the prognosis when the cut-off values of PD-L1 were 10% ( P = 0.404 ), 15% ( P = 0.208 ), and 20% ( P = 0.408 ). The positive expression of YWHAZ (hazard ratio 6.215; 95% confidence interval 3.214-12.017; P < 0.05 ) was an independent adverse prognostic factor for OS. YWHAZ may be an important oncogene in the occurrence and development of DLBCL and may be used as a therapeutic target. PD-L1 may be an oncogene or tumor suppressor gene in the occurrence and development of DLBCL. Different cut-off values of PD-L1 may affect the prognosis of DLBCL.

Background. Adriamycin (doxorubicin) is an important traditional drug that exhibits cytotoxicity in Diffuse Large B-cell Lymphoma (DLBCL). Doxorubicin affects the DLBCL cells at all stages of their cell cycle. Combined with our previous results, this study discovered that the overexpression of hsa-miR-28-5p inhibited the proliferation, promoted apoptosis, and triggered cell cycle arrest at the S-phase in DLBCL cells. However, the effect of (Homo sapiens, hsa)-microRNA (miR)-28-5p on doxorubicin sensitivity in DLBCL has not been investigated. This study aims to reveal the effects of hsa-miR-28-5p on doxorubicin sensitivity at the level of DLBCL cells. Methods. To determine the optimal concentration of doxorubicin, different concentrations of doxorubicin were used to treat DLBCL cells. CCK-8 assay was used to detect the proliferation of DLBCL cells. The hsa-miR-28-5p-mimic NC and hsa-miR-28-5p mimic were transfected to doxorubicin-mediated DLBCL cells. Simultaneously, blank control groups were set up. The cells were cultured and transfected for 24 h. Next, each group was administered with different concentrations of doxorubicin and cultured again for 24 h to observe the effects of hsa-miR-28-5p on doxorubicin sensitivity at different times. The proliferation, early apoptosis, and late apoptosis in DLBCL cells were determined using soft agar colony-forming assay, mitochondrial membrane potential assay, and caspase-3 activity assay, respectively. The apoptosis and cell cycle were explored using Annexin V-PE/7-AAD and PI/RNase staining buffer, respectively. We speculated that PD-L1 might be involved in the effect of hsa-miR-28-5p on the sensitivity of adriamycin (doxorubicin) in the DLBCL cells. Hence, we performed immunohistochemistry (IHC) to determine PD-L1 expression within formalin-fixed paraffin-embedded (FFPE) samples from 52 DLBCL cases. Results. The optimal concentration of doxorubicin targeting DLBCL cells was found to be 3.028 μmol/l. The effect of doxorubicin on DLBCL cells was time- and concentration-dependent. hsa-miR-28-5p mimic + doxorubicin remarkably decreased proliferation of DLBCL. DLBCL cell apoptosis rate was the highest in hsa-miR-28-5p mimic + doxorubicin group. Apart from that, hsa-miR-28-5p mimic plus doxorubicin had the best effect in promoting DLBCL cell apoptosis. After the intervention of hsa-miR-28-5p mimic + doxorubicin on DLBCL cells, the cell cycle was arrested in the S-phase and DNA synthesis was blocked. hsa-miR-28-5p mimic + doxorubicin could regulate the cycle of DLBCL cells. As a result, overexpression of hsa-miR-28-5p combined with doxorubicin is possibly involved in the development of DLBCL by affecting the proliferation, apoptosis, and cycle of DLBCL cells. PD-L1 showed an association with the prognosis of DLBCL patients. Combining with the literature, this suggested hsa-miR-28-5p may influence DLBCL occurrence and therapeutic effect by regulating the PD-L1 level. Conclusion. The combination of hsa-miR-28-5p mimic and doxorubicin may be considered more effective in inhibiting growth, arresting the cell cycle, and promoting cell apoptosis of DLBCL cells compared to using doxorubicin alone. The effects of doxorubicin on DLBCL cells were found to be time- and concentration-dependent. The overexpression of hsa-miR-28-5p enhanced the effect of doxorubicin on DLBCL cells, which may be attributed to the regulation of PD-L1 levels.