Identification of Piwi-Interacting RNA-32260 As a Prognostic Marker for Diffuse Large B-Cell Lymphoma

Background

Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphoma in adults and is highly heterogeneous, which is aggressive and has a poor prognosis. The development of genomics technology has led to the increasing use of noncoding small RNAs for molecular classification of DLBCL, which has become an indicator for disease diagnosis, stratification, prognostic monitoring and a potential therapeutic target.

Aim

To clarify the differential expression of PIWI-interacting RNAs(piRNAs) in DLBCL patients and their impact on survival, and to investigate the potential of piRNAs as biomarkers for DLBCL.

Methods

piRNA-seq was performed on paraffin specimens of lymph nodes from 4 reactive hyperplastic lymph nodes and 11 DLBCL patients. To extend the validation range, 102 paraffin tissue specimens of lymph nodes from DLBCL patients and 31 paraffin tissue specimens of reactive hyperplastic lymph nodes were collected between January 2016 and December 2019, and piRNAs with differential expression were validated by RT-PCR. The X-title software was used to find the optimal cut-off value for survival grouping. The Kaplan-Meier survival analysis was used to analyse the relationship between patient piRNA levels and survival. Differences in piRNA levels across clinical characteristics and treatment response were analyzed using t-tests or chi-square tests.

Results

The sequencing of paraffin specimens showed differential piRNA expression in lymph node tissues of normal controls and DLBCL patients. RT-PCR validation of expanded samples of differentially expressed piRNAs showed that piR-32260, piR-23670, piR-963, piR-12487, piR-15022, piR-23822, piR-27283, and piR-32256 were significantly elevated in DLBCL when compared to normal controls (p=0.001; <0.001; 0.0048; <0.001; <0.001; 0.0013; 0.0078; 0.0407). The expression of piR-28851 and piR-32163 was significantly reduced compared to normal controls (p=0.0002; 0.0478). Among them, piR-32260 had the largest mean difference, therefore we chose it as our candidate piRNA. To explore the clinical significance of piRNAs, we followed patients with DLBCL for a median of 46 months, and divided the patients into piRNA-high and piRNA-low groups. piR-32260 was found to be highly expressed in the DLBCL tumor tissues, and the patients in the piRNA-high group had significantly worse overall survival (OS) than the patients in the piRNA -low group of patients (p=0.0060). In addition, we found that piR-32260 expression was higher in patients >60 years of age than in patients ≤60 years of age (p=0.0447), and higher in patients with bone marrow involvement than in those without (p=0.0302). piR-32260 was not differentially expressed in GCB and Non-GCB subtypes, genders, Ann Arbor staging, LDH, IPI score, Bulky disease, β2M protein, and response to therapy.

Conclusion

In conclusion, piR-32260 was highly expressed in patients with DLBCL, and patients with high expression of piR-32260 had worse survival, the piR-32260 effectively predicted survival in DLBCL.

No relevant conflicts of interest to declare.