Primary testicular (PT) diffuse large B-cell lymphoma (DLBCL) is a rare and aggressive lymphoma with distinct clinical and molecular characteristics. To identify prognostic biomarkers in PT-DLBCL, in this study we analyzed DNA and RNA samples of PT-DLBCL tumors from 206 patients using next-generation sequencing platforms and assays. Genetic alteration analysis found that multiple chromosomal copy number variations (CNVs), TP53 transcript mutations with high variant allele frequency, and MCD subtype had significantly adverse prognostic effects, whereas elevated microsatellite instability had a significantly favorable prognostic effect in PT-DLBCL. Targeted RNA-seq analysis identified a PTL gene expression signature by comparing PT-DLBCL with systemic DLBCL and revealed the heterogeneity within PT-DLBCL by unsupervised clustering, which classified PT-DLBCLs into a testicular lymphoma tumor (TLT) subtype and a microenvironment (ME) subtype. The TLT subtype featured upregulation of genes functioning in DNA damage response, DNA repair, chromatin remodeling, the cell cycle, and the nucleus, and was associated with significantly poorer patient survival and higher frequencies of MYD88 mutations, multiple CNVs, MCD subtype, bulk tumors, and elderly patients in the PT-DLBCL cohort. In contrast, the ME subtype distinctively featured upregulation of various signaling pathway genes involving the tumor microenvironment and downregulation of BTK and B-cell receptor signaling genes, and was associated with significantly better clinical outcome than the TLT subtype of PT-DLBCL independently of CNVs, MCD and MYD88 mutation and than systemic DLBCL. Moreover, genomic microRNA profiling analysis identified a PTL microRNA signature significantly differentially expressed between PT-DLBCL and systemic DLBCL patients and within the PT-DLBCL cohort, and PT-DLBCL patients with higher expression of 16 PTL microRNAs (14 are testicular tissue-specific) had significantly better survival. In summary, this study revealed the molecular heterogeneity in genetic abnormalities and expression profiles of coding genes and microRNAs within the PT-DLBCL entity, and identified significant prognostic biomarkers and PTL signatures.
原发性睾丸弥漫性大B细胞淋巴瘤是一种罕见且侵袭性的淋巴瘤，具有独特的临床和分子特征。为识别PT-DLBCL的预后生物标志物，本研究通过新一代测序平台对206例患者的肿瘤DNA和RNA样本进行分析。遗传改变分析显示，多重染色体拷贝数变异、高变异等位基因频率的TP53转录突变及MCD亚型均对预后有显著不利影响，而升高的微卫星不稳定性则对PT-DLBCL预后具有显著有利影响。靶向RNA测序分析通过比较PT-DLBCL与系统性DLBCL，鉴定出PTL基因表达特征，并借助无监督聚类揭示了PT-DLBCL内部的异质性，将其分为睾丸淋巴瘤肿瘤亚型和微环境亚型。TLT亚型以DNA损伤反应、DNA修复、染色质重塑、细胞周期及细胞核相关基因的上调为特征，且在PT-DLBCL队列中与患者生存率显著更低、MYD88突变频率更高、多重拷贝数变异、MCD亚型、大块肿瘤及老年患者更常见相关。相比之下，ME亚型独特地表现为涉及肿瘤微环境的多条信号通路基因上调，以及BTK和B细胞受体信号基因下调；其临床结局显著优于PT-DLBCL中的TLT亚型（独立于拷贝数变异、MCD亚型和MYD88突变），也优于系统性DLBCL。此外，基因组微RNA谱分析鉴定出在PT-DLBCL与系统性DLBCL之间及PT-DLBCL内部显著差异表达的PTL微RNA特征；16种PTL微RNA表达较高（其中14种为睾丸组织特异性）的PT-DLBCL患者生存率显著更好。总之，本研究揭示了PT-DLBCL实体在编码基因和微RNA的遗传异常及表达谱方面的分子异质性，并鉴定了重要的预后生物标志物和PTL特征。
肿瘤(癌症)患者之家