Jivko Kamarashev

Human Leukocyte Antigen G Up-Regulation in Lung Cancer Associates with High-Grade Histology, Human Leukocyte Antigen Class I Loss and Interleukin-10 Production

Immune evasion in lung cancer results from both structural and functional alterations of human leukocyte antigen (HLA) class I molecules and the local release of immunosuppressive cytokines. Recent data suggest that HLA-G, a nonclassical class Ib molecule, is involved in immune evasion by tumor cells. We sought to determine whether HLA-G could contribute to immunescape in lung cancer. All of 19 tumor specimens examined demonstrated detectable membrane-bound (HLA-G1), as well as soluble (HLA-G5) isoform transcription. Nine of 34 (26%) tumors were positive by immunohistochemistry using monoclonal antibody (mAb) 4H84, recognizing all denatured HLA-G isoforms, of which six were positive using mAb 16G1, recognizing soluble HLA-G. HLA-G immunoreactivity correlated with high-grade histology, with HLA-G being preferentially expressed on large-cell carcinomas. In these patients, loss of classical HLA class I molecules was observed to associate with HLA-G protein up-regulation. Moreover, we found interleukin-10 expressed in 15 of 34 (44%) tumors, and in most of the HLA-G-positive cases (7 of 9), suggesting up-modulation of HLA-G by interleukin-10. It is conceivable that HLA-G expression in lung cancer might be one of the ways how the tumor down-regulates host immune response, in addition to interleukin-10 production and HLA class I loss.

Tyrosinase immunoreactivity in formalin-fixed, paraffin-embedded primary and metastatic melanoma: frequency and distribution

Monoclonal antibody T311 specifically detects tyrosinase protein expression. Tyrosinase‐derived peptides are recognized by CD8+ T‐celis and applied in immunotherapy. We examined formalin‐fixed paraffin‐embedded tissue of 50 melanoma (primary n=31, metastatic n=19) and 41 control cases (junctional, dermal, compound, Spitz, Reed, balloon‐cell nevi) by immunochemistry using the alkaline phosphatase‐anti‐alkaline phosphatase method after antigen retrieval. Staining with mAb T311 showed a sensitivity of 94% for melanoma with a very high specificity for melanocytic cells. Immunopositivity (94% of melanomas overall) correlated inversely with clinical stage: clinical stage I and stage II showed 100%, stage III and stage IV 86% immunoreactivity each. Staining changed from an exclusively homogeneous pattern in early stages to a more heterogeneous pattern in later stages. Melanocytic control tissue like nevi of different subtypes all showed weak to moderate, homogeneous immunoreactivity with polarity towards the epidermis. RT‐PCR ELISA analysis of short‐term melanoma cell cultures displayed mRNA expression in only half of the originally immunopositive tumors only, suggesting rapid mRNA expression loss in culture. mAb T311 allows detection of melanoma‐associated tyrosinase protein expression and thus profiling of melanomas using routine archival tissue suited for immunotherapy approaches involving tyrosinase derived epitopes.

Melan A/MART-1 immunoreactivity in formalin-fixed paraffin-embedded primary and metastatic melanoma: frequency and distribution

Monoclonal antibody (MAb) A103 specifically detects Melan A/MART-1 protein expression. Melan A/MART-1 -derived peptides are recognized by CD8+ T-cells and are used in immunotherapy. We examined formalin-fixed paraffin-embedded tissue from 57 melanomas (34 primary, 23 metastatic) and 39 control cases (junctional, dermal, compound, Spitz, Reed and balloon-cell naevi) using the alkaline phosphatase and anti-alkaline phosphatase immunochemical method after antigen retrieval. Immunoreactivity was rated as low, medium or high, and staining pattern as homogeneous or heterogeneous. Staining with MAb A103 showed a sensitivity of 88% for melanoma, with a very high specificity for melanocytic cells. Immunopositivity decreased along with clinical stage, with stage I showing 100%, stage II 88%, stage III 90% and stage IV 75% immunoreactivity. Staining changed from an exclusively homogeneous pattern in the early clinical stages to a more heterogeneous pattern in the later stages. Melanocytic control tissues consisting of naevi of different subtypes all showed weak to moderate homogeneous immunoreactivity, with polarity towards the epidermis. Analysis of short-term melanoma cell cultures using reverse transcription-polymerase chain reaction (RT-PCR) enzyme-linked immunosorbent assay (ELISA) demonstrated mRNA expression in only one third of the originally immunopositive tumours, suggesting rapid mRNA expression loss in culture. MAb A103 allows the detection of melanoma-associated Melan A/MART-1 protein expression in routine archival tissue and thus enables the profiling of melanomas suited for immunotherapy approaches involving Melan A/MART-1 derived epitopes.

Heterogeneous Tumor Subpopulations Cooperate to Drive Invasion

Summary Clonal selection and transcriptional reprogramming (e.g., epithelial-mesenchymal transition or phenotype switching) are the predominant theories thought to underlie tumor progression. However, a “division of labor” leading to cooperation among tumor-cell subpopulations could be an additional catalyst of progression. Using a zebrafish-melanoma xenograft model, we found that in a heterogeneous setting, inherently invasive cells, which possess protease activity and deposit extracellular matrix (ECM), co-invade with subpopulations of poorly invasive cells, a phenomenon we term “cooperative invasion”. Whereas the poorly invasive cells benefit from heterogeneity, the invasive cells switch from protease-independent to an MT1-MMP-dependent mode of invasion. We did not observe changes in expression of the melanoma phenotype determinant MITF during cooperative invasion, thus ruling out the necessity for phenotype switching for invasion. Altogether, our data suggest that cooperation can drive melanoma progression without the need for clonal selection or phenotype switching and can account for the preservation of heterogeneity seen throughout tumor progression.

Epidemiology of pemphigus in Sofia, Bulgaria. A 16‐year retrospective study (1980–1995)

Background Pemphigus is a disease showing an uneven geographical distribution. In Bulgaria pemphigus has always represented a substantial part of diagnosed bullous diseases, but previous epidemiological data are incomplete. Our purpose was to evaluate retrospectively the incidence and prevalence of pemphigus in the district of Sofia (the capital of Bulgaria; population 1 200 000) for a sixteen‐year period.

Comparative analysis of histological and immunohistological features in mycosis fungoides and Sézary syndrome.

Mycosis fungoides (MF) and Sezary syndrome (SS) are closely related cutaneous T‐cell lymphotmas, which differ in several clinical aspects. We compared histological and immunophenotypical features of these two entities, which could be implicated in the dermotropism and epidermotropism, characteristic for both of them. Thirteen biopsy specimens from patients with established plaque‐stage MF and 13 from SS patients were examined retrospectively, and 21 histological criteria were assessed. Further, 9 cryosections from MF lesions and 9 from SS lesions were stained for LFA, ICAM1, CD40, CD40‐ligand, CD28, CD80, CTLA‐4, CD86, FAS, FAS‐ligand, CLA and CD 15s. The only histological criteria that showed persistent differences were acanthosis (in 12 of 13 SS and in 7 of 13 MF specimens) and Pautrier collections (detected in 6 SS and 11 MF biopsies). Patterns of staining with the antibodies mentioned above were found to be similar. Our results indicate that these interaction molecules seem to be involved in the pathogenesis of MF and SS, but their immunohistochemical distribution does not contribute to the differentiation between the two entities.

Dissecting the roles of Raf- and PI3K-signalling pathways in melanoma formation and progression in a zebrafish model.

SUMMARY Deregulated Ras signalling is implicated in most human neoplasia, exemplified by melanoma. Whereas Raf activation occurs almost ubiquitously in benign and malignant melanocytic neoplasms, implying an involvement in tumour initiation, phosphoinositide 3-kinase (PI3K) activation occurs predominantly in malignant neoplasms, implying an involvement in malignant progression. Here, we dissect the contributions of these two pathways to tumourigenesis in vivo, by modulating their activities in zebrafish melanocytes. Misexpression of oncogenic Ras (V12RAS) in founder fish induced frequent melanoma, beginning at larval stages, with concomitant activation of Raf-Mek-Erk and PI3K-Akt signalling. Misexpression of effector-domain mutants of V12RAS, or of various downstream effectors, confirmed a selective role for the Raf-Mek-Erk pathway in initiating neoplasia, but highlighted the requirement for additional Ras effector pathways for malignancy. The phenotype of animals with germ-line transmission of V12RAS resembled familial atypical mole and melanoma (FAMM) syndrome: melanocytes displayed hyperplasia, dysplasia, altered terminal differentiation and spontaneously progressed to invasive melanoma. Co-expressing a dominant-interfering form of PI3K abolished V12RAS-induced malignancy, demonstrating a direct role for PI3K signalling in the malignant progression of melanoma in vivo, and highlighting PI3K as a promising target for melanoma therapy.

RASopathic Skin Eruptions during Vemurafenib Therapy

Purpose Vemurafenib is a potent inhibitor of V600 mutant BRAF with significant impact on progression-free and overall survival in advanced melanoma. Cutaneous side effects are frequent. This single-center observational study investigates clinical and histological features of these class-specific cutaneous adverse reactions. Patients and Methods Patients were all treated with Vemurafenib 960 mg b.i.d. within local ethic committees approved clinical trials. All skin reactions were collected and documented prospectively. Cutaneous reactions were classified by reaction pattern as phototoxic and inflammatory, hair and nail changes, keratinocytic proliferations and melanocytic disorders. Results Vemurafenib was well tolerated, only in two patients the dose had to be reduced to 720 mg due to arthralgia. 26/28 patients (93%) experienced cutaneous side effects. Observed side effects included UVA dependent photosensitivity (n = 16), maculopapular exanthema (n = 14), pruritus (n = 8), folliculitis (n = 5), burning feet (n = 3), hair thinning (mild alopecia) (n = 8), curly hair (n = 2) and nail changes (n = 2). Keratosis pilaris and acanthopapilloma were common skin reactions (n = 12/n = 13), as well as plantar hyperkeratosis (n = 4), keratoacanthoma (n = 5) and invasive squamous cell carcinoma (n = 4). One patient developed a second primary melanoma after more than 4 months of therapy (BRAF and RAS wild type). Conclusion Vemurafenib has a broad and peculiar cutaneous side effect profile involving epidermis and adnexa overlapping with the cutaneous manifestations of genetic diseases characterized by activating germ line mutations of RAS (RASopathy). They must be distinguished from allergic drug reaction. Regular skin examination and management by experienced dermatologists as well as continuous prophylactic photo protection including an UVA optimized sun screen is mandatory.

Expression of apoptosis regulators in cutaneous T‐cell lymphoma (CTCL) cells

This study examined cutaneous T‐cell lymphoma (CTCL) cell lines and cutaneous lesions for the presence of Bcl‐2 gene family members and found that the two apoptosis‐inhibiting members Bcl‐xL and Mcl‐1 and the two apoptosis‐supporting members Bad and Bax were expressed. However, Bad was at least partially inactivated by phosphorylation. In skin lesions, the translocation of Bad from the nucleus to the cytoplasm may reflect the Bad inactivation by phosphorylation identified in vivo. Bax is also ineffective, as the non‐steroidal anti‐inflammatory drug sulindac, whose cytotoxic effect is mediated by Bax, could not induce apoptosis in CTCL cell lines. The expression of Bcl‐2, Bcl‐xL, and Mcl‐1 may therefore be sufficient to guarantee the survival of malignant CTCL cells. The Bcl‐x, Mcl‐1, Bad, and Bax proteins were also expressed in all CTCL skin lesions tested. In two patients from whom two biopsies from two different time points of the disease were available, a significant increase in Mcl‐1 expression was found in the later‐stage skin lesion. Overexpression of Mcl‐1 and synthesis of non‐functional Bax may be responsible for the resistance of CTCL cells to the anti‐cancer drugs chlorambucil and sulindac. Copyright

Fascin expression in CD30-positive cutaneous lymphoproliferative disorders

Background: CD30‐positive cutaneous lymphoproliferative disorders (LPD) represent a spectrum of diseases ranging from low‐grade (lymphomatoid papulosis; LyP) to high‐grade (pleomorphic and anaplastic large‐cell lymphoma; PTL, ALCL) with overlapping morphologic and immunophenotypic features. The common phenotypic hallmark is the expression of CD30‐antigen by the tumor cells which morphologically resemble Reed–Sternberg cells. Although LyP is a non‐fatal recurring disorder, it is associated with systemic lymphomas including Hodgkins lymphoma (HL), mycosis fungoides (MF) and ALCL in 5–20% of the cases. Currently there is no marker to predict the development of systemic lymphomas in patients with LyP. Fascin, an actin bundling protein, has recently been shown to be a unique marker found in almost 100% of classical HL.