Proximal tibial osteophytes and their relationship with the height of the tibial spines of the intercondylar eminence: paleopathological study

Tibial spiking (i.e., spurring of tibial spines), eburnation, and osteophytes are considered features of osteoarthritis. This investigation employed direct inspection of the medial and lateral tibial plateaus in paleopathological specimens to analyze the frequency and morphological features of osteoarthritis and to define any relationship between the size of osteophytes and that of the intercondylar tibial spines. A total of 35 tibial bone specimens were evaluated for the degree of osteoarthritis and presence of eburnation. Each plateau was also divided into four quadrants and the presence and size of bone outgrowths were recorded in each quadrant. The “medial/lateral tibial intercondylar spine index” for each specimen was calculated as follows: (medial/lateral intercondylar tibial spine height)/(anteroposterior width of the superior tibial surface). The relationships between medial and lateral tibial height indexes with the degree of osteoarthritis were then tested. Osteophytes were observed more frequently in the anterior quadrants of both tibial plateaus than in the posterior quadrants (29 vs 16 for the medial tibial plateau [p = 0.01] and 28 vs 20 for the lateral tibial plateau [p = 0.04]). Eburnation was seen more frequently in the posterior regions of both tibial plateaus than in the anterior regions (17 vs 5, p < 0.01). In specimens with no signs of osteoarthritis the lateral intercondylar tibial index was significantly lower than that in specimens with some degree of osteoarthritis (p = 0.02). The medial intercondylar tibial index of the specimens with no signs of osteoarthritis was not significantly different from that of the specimens with some degree of osteoarthritis (p = 0.45). There was a positive correlation between the lateral spine height index and the overall grading of osteoarthritis, (r = 0.6, p < 0.01). In the anteromedial and posteromedial quadrants of the lateral tibial plateau, the association between the lateral intercondylar tibial spine index and the grade of osteophytes was 0.5 (p < 0.01) and 0.7 (p < 0.01) respectively. Spiking of the lateral tibial intercondylar spine is associated with osteophyte formation and osteoarthritis. Eburnation occurs mainly in the posterior parts of the tibial plateaus while osteophytes arise mainly in the anterior parts. These findings suggest that stresses occurring in the flexed knee may contribute to many of the morphological abnormalities of osteoarthritis

Molecular features and functional consequence of CD44 activation by a novel recurrent IGH translocation t(11;14) (p13;q32) in mature B-cell lymphoid neoplasm

Poster Session 8 - Functional Identification of New Cancer Genes: abstract no. 258Dysregulation of an oncogene by translocation to Ig locus is a common event in the pathogenesis of most non-Hodgkin’s lymphoma. Using inverse-PCR, CD44 on 11p13 was identified as a novel translocation partner of IgH in 9 of 114 cases of gastric, non-gastric extranodal, follicular and nodal diffuse large B-cell lymphomas (DLBCLs) analyzed. IgHSμ/CD44 translocation juxtaposes the enhancer of IgHSμ to the 5’ regulatory region of CD44 in a tail-to-head orientation, leading to the removal of exon 1 of CD44. Sequencing analysis showed microhomology sequences at the junction breakpoints of all the IGHSμ/CD44 translocations, suggesting that these translocations were the results of illegitimate switch recombination facilitated by homologous sequences present on both chromosomes. By interphase-FISH using home-grown CD44 dual-color break-apart probes (consisting of BACs RP4-607I7 and RP4-683L5), breakage at the CD44 locus in each of the nine IGHSμ/CD44 translocation-positive cases was confirmed. By 5’ RACE analysis, fusion Iμ-CD44ΔEx1 hybrid transcripts (with a splicing of the Iμ exon upstream of Sμ to exon 2 of CD44), were identified in all the nine lymphomas with IGHSμ/CD44 translocations. Notably, these translocations were detected exclusively in GCB-type DLBCLs. However, CD44 mRNA was minimally or not expressed in CD10+ microdissected reactive GCB cells. The IGHSμ/CD44 translocation substitute Sμ for the CD44 promoter and remove exon 1 of CD44, resulting in over-expression of the Iμ-CD44 hybrid transcript which encodes for a new CD44 variant lacking leader peptide sequence but retaining a unique C-terminus (CD44ΔEx1). The Iμ-CD44ΔEx1 ORF would encode for the CD44ΔEx1 protein starting from the ATG at nucleotide 254 with strong Kozak sequence. The new CD44ΔEx1 variant showed some similarity to CD44v5, but it lacked the leader peptide. The IGHSμ/CD44 translocation was detected in patients with advanced-stage disease (stages III and IV). When overexpressed in vitro in the CD44-negative GCB-DLBCL cell line BJAB, the CD44ΔEx1-GFP was localized to the cytoplasm and nucleus, while CD44s-GFP (standard form) was localized to the plasma membrane. The ectopic expression of CD44ΔEx1 in BJAB cells enhanced the cell proliferation rate and its clonogenic ability. These findings indicate a possible pathogenic role of the recurrent translocation in several malignant B-cell lymphomas.link_to_OA_fulltextThe 101st Annual Meeting of the American Association for Cancer Research (AACR 2010), Washington D.C., 17-21 April 2010. In AACR Meeting Abstracts, 201

CD44 expression is regulated by translocation and promoter hypermethylation in gastric lymphoma

One of the major genetic features of non-Hodgkin’s lymphomas (NHL) is the chromosomal translocation, most frequently involving the immunoglobulin heavy chain (IGH) gene at band 14q32. By employing the IgH dual color, break apart rearrangement probe (Vysis Inc.) for interphase FISH; followed by the long-distance inverse polymerase chain (LDI-PCR) strategy, we identified CD44 at chromosome 11p13 as a novel translocation partner gene of IGH in primary GL. The IGH/CD44 t(11;14)(p13;q32) was detected in 40% (4/10) mucosa-associated lymphoid tissue (MALT) lymphoma (3 positive cases are transformed MALT lymphoma cases) and 10% (4/40) diffuse large B-cell lymphoma (DLBCL) cases. This finding makes CD44 as the first cell adhesion molecule involving the IGH translocation and the third gene identified that involves the IGH translocation in MALT lymphoma. Immunohistochemistry showed that CD44 was expressed strongly in the membrane and cytoplasm of the tumor cells in 40% (4/10) MALT cases and 67.5% (27/40) DLBCL cases, including 8 IGH/CD44 translocation positive cases, while the remaining cases showed very weak or no CD44 expression. We next determined whether the hypermethylation of the promoter region of CD44 gene was responsible for the downregulation of CD44 in GL cases lacking CD44 expression. We first analyzed 10 mature B-cell lymphoma cell lines for the CD44 methylation status by methylation-specific PCR (MSP) and bisulfite genomic sequencing (BGS). Methylated alleles were detected in all the cell lines lacking CD44 expression but not in cell lines with CD44 expression. The treatment of the cell lines lacking CD44 with the demethylation agent 5-Aza-dC restored the CD44 expression. In the GL cases, methylated alleles were detected in 42% (21/50) cases and they significantly correlated with weak or no CD44 protein expression in the tumor cells. The most interesting observation was that the 3 CpG sites contained by E2F, Sp1 and EGR1 were nearly always methylated in cell lines lacking CD44 expression but not in the cell lines with CD44 expression. Similar results were also found in the GL cases. The correlation of CD44 expression and clincopathological parameters showed that strong CD44 expression was associated with poor prognosis in GL, and the cases with unmethylated CD44 were positively correlated with high stage (p=0.023). Overall, our results show that CD44 expression is regulated by different mechanisms operating simultaneously in GL, chromosomal translocation in cases with strong CD44 expression and gene silencing by promoter hypermethylation in cases lacking CD44

CD44 activation in mature B-cell malignancies by a novel recurrent IGH translocation

Using inverse polymerase chain reaction, we identified CD44, located on chromosome 11p13, as a novel translocation partner of IGH in 9 of 114 cases of gastric, nongastric extranodal, follicular, and nodal diffuse large B-cell lymphoma (DLBCL). Notably, these translocations involving IGHSμ were detected in follicular lymphomas and exclusively in germinal center B cell - like (GCB) - DLBCLs. CD44 is not expressed in reactive GC B cells. The IGHSμ/CD44 translocations substitute Sμ for the CD44 promoter and remove exon 1 of CD44, resulting in the overexpression of Iμ-CD44 hybrid mRNA transcripts activated from derivative 11 that encode a new CD44 variant lacking the leader peptide and with a unique C-terminus (CD44ΔEx1). When overexpressed in vitro in the CD44 - GCB-DLBCL cell line BJAB, CD44ΔEx1 - green fluorescent protein localized to the cytoplasm and nucleus, whereas CD44s - green fluorescent protein (standard form) localized to the plasma membrane. The ectopic expression of CD44ΔEx1 in BJAB cells enhanced their proliferation rate and clonogenic ability, indicating a possible pathogenic role of the translocation. © 2010 by The American Society of Hematology.link_to_OA_fulltex