Structural variability of the carboxy‐terminus of Epstein–Barr virus encoded latent membrane protein 1 gene in Hodgkin's lymphomas

Abstract

Epstein-Barr virus (EBV) is implicated in the pathogenesis of several lymphoid and epithelial neoplasms. Latent membrane protein 1 (LMP1) is the major viral oncogene and it is controversial whether tumor LMP1 variants reflect their geographical predominance or are associated with enhanced oncogenic properties. This study aimed to analyze LMP1 molecular variability of 62 EBV+ Hodgkin's lymphomas and 22 non-neoplastic controls from Brazil and Argentina. EBV association was characterized by EBER-ISH, LMP1 immunohistochemistry and PCR assays for EBNA2 and 3C (typing), LMP1 30 bp deletion (del30) and number of 33 bp tandem repeats. LMP1 C-terminal sequencing was performed in 42 cases. EBV1 was the predominant strain in both geographical Hodgkin's lymphoma groups (average 82%). A higher frequency of del30 variant was observed in lymphomas (41/63) than in non-neoplastic controls (6/22) (OR 4.97, CI 95% 1.53-16.79; P = 0.005, chi(2) test). A large number (5-7) of 33 bp repeat units was characteristic of del30 LMP1 variants (P < 0.0001, Fisher's exact test). Sequence analysis showed a similar mutation spectrum to that described worldwide but none of the current classification schemes could be applied completely. A distinct structural pattern was observed in del30 variants, characterized by a large number of 33 bp repeat units and the presence of a 15 bp insertion encoding the JAK3 Box-1a motif (3/15 wt vs. 16/20 del30; P = 0.001, chi(2) test). The results suggest a pathogenic role for LMP1 del30 variants in Hodgkin's lymphoma from South America and point to particular virus-host molecular mechanisms, such as genomic instability in LMP1 carboxy-terminus, leading to enhanced production and selection of these deletion variants.

Distinctive Epstein-Barr Virus Variants Associated with Benign and Malignant Pediatric Pathologies: LMP1 Sequence Characterization and Linkage with Other Viral Gene Polymorphisms

“…Additionally, 7/15 cases (46.7%) contained ins15 in the rep33 zone (Table 1). This JAK3 signaling motif insertion was previously described by other authors within the third repeated unit of rep33 and is also present in strain B95.8 (14,28,40), but in the IM samples studied here ins15 was detected either within the third or the fourth repetitive unit; i.e., in patients IM3 and IM7 in the third one and in patients IM5, IM6, IM8, IM12, and IM14 in the fourth (Fig. 3).…”

“…Particularly in Argentina, the deleted LMP1 variant was previously preferentially detected in tumor samples rather than in samples from healthy individuals, either adults (8,9) or children (5). The predominance of the del30 variant within tumors also was described in the rest of South America and Mexico, and it is in this geographic region that this distinct distribution scheme is more clearly observed (6,7,11,14,18). In the present series, del30 variants were detected in tumor samples and in IM with a similar high incidence.…”

“…In both cases the 5= end of the C-ter of LMP1 corresponded to the Med strain, while the 3= end was characterized as the China 2 strain in patient IM2 and the China 3 strain in patient IM3. The site of recombination was determined for both patients within the rep33 zone, which was previously described as very favorable for recombination events to occur (14). The recombinant variants detected in these two patients were confirmed by phylogenetic reconstruction, but on this occasion the 5= end and the 3= end were analyzed independently with the corresponding fragments from prototype sequences, and the rep33 region was excluded from the analysis.…”

“…Although LMP1 sequence variants have been deeply studied in a wide variety of malignancies in different geographic regions (6), only a few studies addressed this issue in pediatric patients (2,5,14), and to the best of our knowledge, only one of these included pediatric cases of IM (2). With the aim of disclosing current conflicts arising from the different sample types used in other studies and/or particular health conditions, this work addressed sequence variation within the C-ter region of LMP1 in different compartments from children with IM during primary infection and its convalescence, and also from pediatric EBV-related lymphomas from Argentina.…”

Clinical and demographic characteristics of Epstein-Barr virus-associated childhood Burkitt's lymphoma in Southeastern Brazil: epidemiological insights from an intermediate risk region

“…17 However, in a group of Hodgkin's lymphomas (HL) from our institution, a significant association of del30 variants with lymphoma cases was observed. 7 These differences may reflect the fact that LMP1 is expressed and therefore subjected to selection in HL but not in BL, in which EBV expresses a restricted pattern of gene expression (latency I). Children with AIDS-BL were younger than immunocompetent BL children, as expected from perinatal HIV infection, confirmed in 3 patients.…”