Primary Cutaneous T-Cell Lymphomas Do not Show Specific NAV3 Gene Deletion or Translocation

TP53 alterations in primary and secondary Sézary syndrome: A diagnostic tool for the assessment of malignancy in patients with erythroderma

Recent massive parallel sequencing data have evidenced the genetic diversity and complexity of Sézary syndrome mutational landscape with TP53 alterations being the most prevalent genetic abnormality. We analyzed a cohort of 35 patients with SS and a control group of 8 patients with chronic inflammatory dermatoses. TP53 status was analyzed at different clinical stages especially in 9 patients with a past-history of mycosis fungoides (MF), coined secondary SS. TP53 mutations were only detected in 10 patients with either primary or secondary SS (29%) corresponding to point mutations, small insertions and deletions which were unique in each case. Interestingly, TP53 mutations were both detected in sequential unselected blood mononuclear cells and in skin specimens. Cytogenetic analysis of blood specimens of 32 patients with SS showed a TP53 deletion in 27 cases (84%). Altogether 29 out of 35 cases exhibited TP53 mutation and/or deletion (83%). No difference in prognosis was observed according to TP53 status while patients with secondary SS had a worse prognosis than patients with primary SS. Interestingly, patients with TP53 alterations displayed a younger age and the presence of TP53 alteration at initial diagnosis stage supports a pivotal oncogenic role for TP53 mutation in SS as well as in erythrodermic MF making TP53 assessment an ancillary method for the diagnosis of patients with erythroderma as patients with inflammatory dermatoses did not display TP53 alteration.

Analysis of differential β variable region of T cell receptor expression and NAV3/TNFRSF1B gene mutation in mycosis fungoides

Objective

This study aimed to analyze the predominant expression of the variable region of T cell receptor (TRBV) and determine whether NAV3 or TNFRSF1B gene mutation involved in the pathogenesis of MF.

Results

TRBV5-7 expression increased from the normal, early-stage to advanced-stage lesion in MF patient. By contrast, TRBV2 decreased with the lesion developed. We found no mutations of NAV3 or TNFRSF1B in the lesions from this study.

Materials and Methods

Real-time PCR were used to screen differential expression of TRBV in different lesions. Mutational analyses were used to validate genetic alterations in the skin lesions.

Conclusions

The identification of TRBV gene expression differences between normal and different stages of MF lesions provide insight into promising new diagnostic and prognostic biomarkers. None of the reported genetic abnormalities suggests complexity of progress from a primary cytogenetic event to an advanced stage with poor prognosis in MF.

PLCG1 Gene Mutations in Cutaneous T-Cell Lymphomas Revisited

The observation that mutations in the phospholipase C gamma 1 (PLCG1) gene (among which p.S345F was shown to be activating) are frequent (20%) in tumoral cutaneous T-cell lymphoma (CTCL) samples raised the possibility of targeting therapies against the PLCG1 signaling pathway. However, new data by Caumont et al. in this issue of JID show that PLCG1 mutations are far less prevalent than expected in CTCLs, which tempers the initial enthusiasm. This new study finds that only 3-5% of the CTCL tumor genomes (mycosis fungoides and Sézary syndrome) harbor PLCG1 mutations.

Navigator-3, a modulator of cell migration, may act as a suppressor of breast cancer progression

Dissemination of primary tumor cells depends on migratory and invasive attributes. Here, we identify Navigator-3 (NAV3), a gene frequently mutated or deleted in human tumors, as a regulator of epithelial migration and invasion. Following induction by growth factors, NAV3 localizes to the plus ends of microtubules and enhances their polarized growth. Accordingly, NAV3 depletion trimmed microtubule growth, prolonged growth factor signaling, prevented apoptosis and enhanced random cell migration. Mathematical modeling suggested that NAV3-depleted cells acquire an advantage in terms of the way they explore their environment. In animal models, silencing NAV3 increased metastasis, whereas ectopic expression of the wild-type form, unlike expression of two, relatively unstable oncogenic mutants from human tumors, inhibited metastasis. Congruently, analyses of > 2,500 breast and lung cancer patients associated low NAV3 with shorter survival. We propose that NAV3 inhibits breast cancer progression by regulating microtubule dynamics, biasing directionally persistent rather than random migration, and inhibiting locomotion of initiated cells.

Histopathologic diagnosis of lymphomatous versus inflammatory erythroderma: a morphologic and phenotypic study on 47 skin biopsies

Erythroderma may be secondary to a cutaneous T-cell lymphoma (CTCL) and various other erythrodermic inflammatory dermatoses (EID), and their histopathologic distinction is often difficult. The aim of this study was to determine if morphological parameters, namely: the presence of b-catenin, and JunB (previously shown to be expressed by CTCL cells), the epidermal CD8:CD3 ratio, and CD30 expression may help in the histopathologic diagnosis of erythroderma, especially in differentiating CTCL and EID. We retrospectively reviewed a series of 47 skin biopsies from patients with erythroderma (18 CTCL and 29 EID). The diagnosis of each case was established using clinical, biological and histopathologic data. After a blind assessment of the hematoxylin--eosin--safran stained slides, a correct diagnosis of the underlying cause of erythroderma was made only in 31% of cases. A correct differential diagnosis between lymphoma and EID was done with certainty in 57% of cases. Various morphologic and phenotypic parameters were then recorded and we compared their frequency in the CTCL versus the EID group. With the exception of atypical lymphocytes, the moderate to high density of dermal infiltrates and Pautrier microabcesses, only found in CTCL, no morphologic parameter was found to be specific of CTCL, although single lymphocytes epidermotropism, telangiectasias, and slight lymphocytic dermal infiltrate were significantly more frequent in EID. A low (<10%) CD8:CD3 ratio in the epidermal lymphocytic infiltrate and dermal CD30+ lymphocytes were significantly more frequent in CTCL. JunB expression by lymphocytes was specific of CTCL, but was inconstant in our series (17%). We found β-catenin expression in a minority of cases from both the CTCL and EID groups. Among EID, dermal suprapapillary thinning was specific of psoriasis. Neutrophils exocytosis and edema of papillary dermis were significantly more frequent in psoriasis, and spongiosis was more frequent in eczema. In conclusion, few morphological and phenotypical parameters are helpful in making a differential diagnosis between erythrodermic CTCL and EID using paraffin embedded skin biopsies.

Genetic alterations in Sezary syndrome

Sezary syndrome (SS) is a rare form of cutaneous T-cell lymphoma characterized by erythroderma and the presence of Sezary cells in the skin, lymph nodes, and peripheral blood. Over the past few decades, cytogenetic and molecular cytogenetic findings have revealed many genetic alterations in patients with SS. The most frequent genetic lesions include monosomy 10, losses of 10q and 17p, gains of 8q24 and 17q, and diverse structural alterations involving these regions. Expression patterns in regions of genomic imbalance show that a large number of genes in SS are deregulated, and this might have a causative role in oncogenesis. Overall, chromosomal instability is characteristic of this lymphoma and related to a poor prognosis, but no specific abnormalities that may be directly involved in development of the disease have yet been found.

CDKN2A-CDKN2B deletion defines an aggressive subset of cutaneous T-cell lymphoma

Inactivation of the CDKN2A-CDKN2B locus has been reported in the most frequent subtypes of cutaneous T-cell lymphomas (CTCLs), mycosis fungoides, Sézary syndrome (SS) and CD30+ cutaneous anaplastic large cell lymphoma. To investigate whether genetic or epigenetic inactivation of CDKN2A-CDKN2B is more specifically observed in certain CTCL subtypes with clinical impact, we used array-comparative genomic hybridization, quantitative PCR, interphase fluorescent in situ hybridization and methylation analyses of p14(ARF) p16(INK4A) and p15(INK4B) promoters. We studied 67 samples from 58 patients with either transformed mycosis fungoides (n=24), SS (n=16) or CD30+ cutaneous anaplastic large cell lymphoma (n=18). We observed combined CDKN2A-CDKN2B deletion in both transformed mycosis fungoides (n=17, 71%) and SS patients (n=7, 44%), but, surprisingly, in only one CD30+ cutaneous anaplastic large cell lymphoma case. Interphase fluorescent in situ hybridization showed 9p21 loss in 17 out of 19 cases, with 9p21 deletion indicating either hemizygous (n=4) or homozygous (n=2) deletion, with mixed patterns in most patients (n=11). The limited size of 9p21 deletion was found to account for false-negative detection by either BAC arrays (n=9) or fluorescent in situ hybridization (n=2), especially in patients with Sézary syndrome (n=6). Methylation was found to be restricted to the p15(INK4B) gene promoter in patients with or without 9p21 deletion and did not correlate with prognosis. In contrast, CDKN2A-CDKN2B genetic loss was strongly associated with a shorter survival in CTCL patients (P=0.002) and more specifically at 24 months in transformed mycosis fungoides and SS patients (P=0.02). As immunohistochemistry for p16(INK4A) protein was not found to be informative, the genetic status of the CDKN2A-CDKN2B locus would be relevant in assessing patients with epidermotropic CTCLs in order to identify those cases where the disease was more aggressive.

Genome-wide analysis of cutaneous T-cell lymphomas identifies three clinically relevant classes

This study was undertaken to identify recurrent genetic alterations of the three main types of cutaneous T-cell lymphomas (CTCLs): mycosis fungoides (MF), Sézary syndrome (SS), and cutaneous anaplastic large-cell lymphoma (CALCL). Using array-based comparative genomic hybridization, the molecular cytogenetic profiles of 72 samples obtained from 58 patients with CTCL corresponding to 24 transformed MF (T-MF), 16 SS, and 18 CALCLs were determined. T-MF was characterized by gains of 1q25-31, 7p22-11.2, 7q21, 7q31, and 17q12, and losses of 9p21, 10p11.2, and 10q26. SS exhibited gains of 8q23-24.3 and 17q23-24, as well as losses of 9p21, 10p12-11.2, 10q22-24, 10q25-26, and 17p13-q11.1. Finally, CALCL exhibited 6q27 and 13q34 losses. Such imbalances were statistically associated with one CTCL subtype. Unsupervised hierarchical clustering defined three categories of clinical relevance: (1) CALCL apart from epidermotropic-CTCL, (2) an SS-only category, and (3) a mixed category with T-MF and SS cases, with both primary and secondary SS cases. In rare cases, the genetic classification did not correspond to the inclusion diagnosis, possibly reflecting the association of two diseases in the same patient or initial misdiagnosis according to follow-up. Finally, different samples in the same patient clustered together, showing reproducibility of such a classifier.

[What's new in dermatological research?]

Fundamental research in Dermatology has been once more very active during the past year and more specifically focused on immunological grounds of inflammatory diseases, the identification of risk loci associated with psoriasis and tumors, cutaneous lymphomas and on the genodermatosis where large international collaborative studies provided with a molecular understanding of an increasing amount of conditions especially affecting pigmentation and differentiation. In silico investigations become increasingly prominent especially with the rising power of new actor, China, the demographical and resulting epidemiological weight of which can hardly be challenged. Some of these fundamental breakthroughs might result in practical interventions although in an undefined future.