Hajnalka Rajnai

EZH2 mutations are frequent and represent an early event in follicular lymphoma

Gain of function mutations in the H3K27 methyltransferase EZH2 represent a promising therapeutic target in germinal center lymphomas. In this study, we assessed the frequency and distribution of EZH2 mutations in a large cohort of patients with follicular lymphoma (FL) (n = 366) and performed a longitudinal analysis of mutation during the disease progression from FL to transformed FL (tFL) (n = 33). Mutations were detected at 3 recurrent mutation hot spots (Y646, A682, and A692) in 27% of FL cases with variant allele frequencies (VAF) ranging from 2% to 61%. By comparing VAF of EZH2 with other mutation targets (CREBBP, MLL2, TNFRSF14, and MEF2B), we were able to distinguish patients harboring clonal EZH2 mutation from rarer cases with subclonal mutations. Overall, the high incidence of EZH2 mutations in FL and their stability during disease progression makes FL an appropriate disease to evaluate EZH2 targeted therapy.

High rate of neoplastic cells with genetic abnormalities in proliferation centers of chronic lymphocytic leukemia

In lymph nodes, chronic lymphocytic leukemia (CLL) cells (prolymphocytes and paraimmunoblasts) form proliferation centers (PCs), which are also known as pseudofollicles. To reveal whether PCs play a role in the accumulation of genetic alterations in CLL, we compared deletion at 11q22.3, 13q14.3, and 17p13.1 loci and trisomy 12 by the fluorescence in situ hybridization (FISH) technique in PCs versus surrounding small lymphocytes (SLs) in 12 formalin-fixed paraffin-embedded (FFPE) lymph nodes. The FFPE sections were stained with methylene blue and PCs were marked by laser beam. Subsequent FISH analysis was performed, relocalizing the previously defined regions. Loss of 11q was detected in five cases, loss of 13q in two cases, loss of 17p in two cases, and trisomy 12 in one case. In seven cases PCs contained a significantly higher ratio of cells with genetic alterations compared with the surrounding SLs. Our results show that CLL cells with genetic alterations tend to accumulate in PCs. The clonal expansion of the cell population carrying genetic alterations within PCs may contribute to CLL progression.

Folliculotropic mycosis fungoides: clinicopathological analysis of 17 patients

Folliculotropic mycosis fungoides (FMF) represents a variant of MF characterized by hair follicle invasion of mature, CD4‐positive small lymphoid cells with cerebriform nuclei. The disease displays resistance to standard treatment modalities and has an unfavourable course.

Epidermal growth factor receptor signalling contributes to osteoblastic stromal cell proliferation, osteoclastogenesis and disease progression in giant cell tumour of bone.

Balla P, Moskovszky L, Sapi Z, Forsyth R, Knowles H, Athanasou N A, Szendroi M, Kopper L, Rajnai H, Pinter F, Petak I, Benassi M S, Picci P, Conti A & Krenacs T
(2011) Histopathology59, 376–389

DNA and RNA Isolated from tissues processed by microwave-accelerated apparatus MFX-800-3 are suitable for subsequent PCR and Q-RT-PCR amplification

Over the past decade, methods of molecular biology have appeared in diagnostic pathology and are routinely applied on formalin-fixed, paraffin-embedded histological samples, processed via conventional embedding methods. Due to its reagent- and cost-effectiveness, embedding techniques that utilize microwave acceleration in one or more steps of histoprocessing are increasingly used by numerous laboratories. The demand arises that tissues processed this way should also be suitable for the requirements of molecular pathology. In this study, both conventionally embedded and MFX-800-3 machine-processed tissue samples from the same source were used for isolation of DNA and RNA and for performing PCR and real-time PCR. PCR amplification of the β-globin gene, as well as the real-time PCR amplification of the ABL mRNA was successful in all cases. Our conclusion is that samples processed by the vacuum assisted automatic microwave histoprocessor MFX-800-3 are perfectly applicable for DNA and RNA isolation and provide appropriate templates for further PCR and realtime PCR studies.

Impact of the reactive microenvironment on the bone marrow involvement of follicular lymphoma

Rajnai H, Bödör C, Balogh Z, Gagyi É, Csomor J, Krenács T, Tóth E & Matolcsy A

Connexin 43 Communication Channels in Follicular Dendritic Cell Development and in Follicular Lymphomas

Follicular dendritic cells (FDC) show homo- and heterocellular metabolic coupling through connexin 43 (Cx43) gap junctions and support B cell selection and maturation in germinal centers. In follicular lymphomas B cells escape apoptosis while FDC develop abnormally. Here we tested Cx43 channels in reactive FDC development and follicular lymphomas. In culture, the treatment of FDC-B cell clusters (resembling to “ex vivo” germinal centers) with Gap27 peptide, mimicking the 2nd extracellular loop of Cx43 protein, significantly impaired FDC-B cell cluster formation and cell survival. In untreated cultures of intact clusters, cell proliferation showed a moderate reduction. In tissues, Cx43 protein levels run parallel with the density of FDC both in reactive germinal centers and in malformed follicles of follicular lymphomas and showed strong upregulation in newly generated and/or degrading bi-/multinuclear FDC of rudimentary processes. However, the inverse correlation between Cx43 expression and B cell proliferation seen in reactive germinal centers was not detected in follicular lymphomas. Furthermore, Cx43 levels were not associated with either lymphoma grade or bone marrow involvement. Our results suggest that Cx43 channels are critical in FDC and “ex vivo” germinal center development and in the persistence of FDC in follicular lymphomas but do not affect tumor progression.

Primary cutaneous aggressive epidermotropic CD8+ T-cell lymphoma : report of two cases with no evidence of systemic disease

ejd.2012.1823 Auteur(s) : Agota Szepesi1 agota@korb1.sote.hu, Judit Csomor1, Hajnalka Rajnai1, Nora Erős2, Norbert Wikonkal2, Sarolta Karpati2, Andras Matolcsy1, Marta Marschalko2 1 1st Department of Pathology, 2 Department of Dermatology, Semmelweis University, Ullői str. 26 Budapest 1085, Hungary Primary cutaneous aggressive epidermotropic CD8+ T-cell lymphoma (AECTCL) is a rare, provisional entity in the 2008 WHO classification [1]. Our new cases represent clinical variants of the [...]

EZH2 is upregulated in the proliferation centers of CLL/SLL lymph nodes

Lymph node involvement of chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) is characterised by the diffuse infiltration of small neoplastic lymphocytes, which is accompanied by the presence of proliferation centres (PCs) comprising prolymphocytes and paraimmunoblasts. There is increasing evidence of accumulation of various molecular alterations in the tumour cells of PCs, which may explain why extended PCs are related to a less favourable prognosis. To further characterize PCs, we compared the expression level of EZH2 protein, the overexpression of which has recently been recognized as poor prognostic factor in CLL/SLL, in the PCs and the intervening small cell areas in lymph nodes of 15 patients with CLL/SLL. We also investigated the mutational profile of EZH2 and the expression of its upstream regulators c-Myc, E2F1, pRB and miR-26a. Our results showed a significantly increased expression of EZH2 in the PCs. No EZH2 mutations were detected, however, overexpression of c-Myc, E2F1 and pRb proteins as well as reduced expression of the tumor suppressor miR-26a were demonstrated in the PCs. In summary our findings indicate that EZH2 pathway is significantly upregulated in the PCs of CLL/SLL lymph nodes, providing further evidence for the distinguished biological features of the PCs.