Department of Hematology, The Affiliated Cancer Hospital of Zhengzhou University, Zhengzhou, Henan Province, China.
Department of Immunotherapy, The Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital, Zhengzhou, Henan Province, China.
Cancer Sci. 2022 Aug;113(8):2888-2903. doi: 10.1111/cas.15402. Epub 2022 Jun 14.
Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy with a high relapse rate of up to 40%. The prognosis of the disease needs improvement and requires a understanding of its molecular mechanism. We investigated the mechanisms of DLBCL development and its sensitivity to chemotherapy by focusing on circPCBP2/miR-33a/b/PD-L1 axis. Human DLBCL specimens and cultured cancer cell lines were used. Features of circPCBP2 were systematically characterized through Sanger sequencing, Actinomycin D, RNase R treatment, and FISH. The expression levels of circPCBP2, miR-33a/b, PD-L1, stemness-related markers, ERK/AKT and JAK2/STAT3 signaling were measured using qRT-PCR, western blotting, and immunohistochemistry. Stemness of DLBCL cells was assessed through spheroid formation assay and flow cytometry. Cell viability and apoptosis upon cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) treatment were determined using MTT assay and flow cytometry, respectively. Interactions of circPCBP2-miR-33a/b and miR-33a/b-PD-L1 were validated using dual luciferase activity assay and RNA-RIP. Nude mouse xenograft model was used to assess the function of circPCBP2 in DLBCL growth in vivo. circPCBP2 was upregulated in human DLBCL specimens and cultured DLBCL cells while miR-33a/b was reduced. Knockdown of circPCBP2 or miR-33a/b overexpression inhibited the stemness of DLBCL cells and promoted cancer cell apoptosis upon CHOP treatment. circPCBP2 directly bound with miR-33a/b while miR-33a/b targeted PD-L1 3'-UTR. circPCBP2 disinhibited PD-L1 signaling via sponging miR-33a/b. miR-33a/b inhibitor and activating PD-L1 reversed the effects of circPCBP2 knockdown and miR-33a/b mimics, respectively. circPBCP2 knockdown restrained DLBCL growth in vivo and potentiated the anti-tumor effects of CHOP. In conclusion, circPCBP2 enhances DLBCL cell stemness but suppresses its sensitivity to CHOP via sponging miR-33a/b to disinhibit PD-L1 expression. circPCBP2/miR-33a/b/PD-L1 axis could serve as a diagnosis marker or therapeutic target for DLBCL.
弥漫性大 B 细胞淋巴瘤 (DLBCL) 是最常见的淋巴恶性肿瘤，其复发率高达 40%。该疾病的预后需要改善，这需要我们了解其分子机制。我们通过关注 circPCBP2/miR-33a/b/PD-L1 轴来研究 DLBCL 的发展机制及其对化疗的敏感性。我们使用了人类 DLBCL 标本和培养的癌细胞系。通过 Sanger 测序、放线菌素 D、核糖核酸酶 R 处理和 FISH 系统地对 circPCBP2 的特征进行了表征。使用 qRT-PCR、western blot 和免疫组化测定 circPCBP2、miR-33a/b、PD-L1、干性相关标志物、ERK/AKT 和 JAK2/STAT3 信号通路的表达水平。通过球体形成测定和流式细胞术评估 DLBCL 细胞的干性。使用 MTT 测定和流式细胞术分别测定环磷酰胺、多柔比星、长春新碱和泼尼松 (CHOP) 处理后细胞活力和细胞凋亡。使用双荧光素酶活性测定和 RNA-RIP 验证 circPCBP2-miR-33a/b 和 miR-33a/b-PD-L1 的相互作用。使用裸鼠异种移植模型评估 circPCBP2 在体内 DLBCL 生长中的作用。circPCBP2 在人类 DLBCL 标本和培养的 DLBCL 细胞中上调，而 miR-33a/b 下调。circPCBP2 敲低或 miR-33a/b 过表达抑制 DLBCL 细胞的干性，并促进 CHOP 处理后的癌细胞凋亡。circPCBP2 与 miR-33a/b 直接结合，而 miR-33a/b 靶向 PD-L1 3'-UTR。circPCBP2 通过海绵吸附 miR-33a/b 来抑制 PD-L1 信号。miR-33a/b 抑制剂和激活 PD-L1 分别逆转了 circPCBP2 敲低和 miR-33a/b 模拟物的作用。circPBCP2 敲低抑制体内 DLBCL 生长并增强 CHOP 的抗肿瘤作用。总之，circPCBP2 通过海绵吸附 miR-33a/b 来抑制 PD-L1 表达，增强 DLBCL 细胞的干性，但降低其对 CHOP 的敏感性。circPCBP2/miR-33a/b/PD-L1 轴可作为 DLBCL 的诊断标志物或治疗靶点。
