Histone H3 K27 alterations in central nervous system tumours: Challenges and alternative diagnostic approaches

Upon the discovery of frequent oncogenic histone alterations in paediatric diffuse high-grade gliomas, the epigenetic and transcriptional landscapes of tumours have become increasingly important aspects of diagnostic and prognostic analysis. The replacement of lysine 27 with methionine in H3 histone variants - H3 p.K28M (K27M) - was the first reported histone mutation associated with human malignancies, seen in up to 80% of paediatric diffuse midline gliomas. This discovery contributed to the updated 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumours in which paediatric diffuse high-grade gliomas were classified into molecular-based categories. Therefore, molecular analysis of tumour cells has become increasingly necessary for determining disease prognosis and potential therapeutic strategies. Although detection of histone alterations is crucial for the diagnosis of specific glioma subtypes, several studies have identified them in other CNS tumours, which may be misleading during routine diagnostic work. While traditional biopsies remain the standard for diagnosis of gliomas, they pose a high risk for surgical complications and patient morbidity. Consequently, this review highlights the importance of the H3 K27-alterations in paediatric gliomas and several other CNS tumours. We also discuss the potential of liquid biopsies as a minimally invasive and highly effective alternative for confirming the diagnosis and potential targeted epigenetic therapies which may improve the survival of patients.

Programmed Death-ligand 1 (PD-L1) Expression in Thymic Epithelial Tumors

Thymic epithelial tumors (TETs) are uncommon neoplasms of the mediastinum. The gold standard treatment is complete surgical resection which can be followed by radio/chemotherapy in selected cases. Targeted tyrosine kinase inhibition can be considered in only a limited number of aggressive or metastatic tumors as EGFR, BRAF, or c-kit mutations are rare. However, previous studies have demonstrated the efficacy of immune checkpoint inhibitors in epithelial neoplasias, such as in programmed cell death ligand 1 (PD-L1) expressing nonsmall cell lung carcinoma. Because of their rare occurrence the data on PD-L1 distribution in thymic neoplasias are limited. PD-L1 and PD-1 expression in tumor cells and tumor infiltrating immune cells was determined in TETs according to criteria published for lung carcinomas. Comparison with major clinical, pathologic, and biological features was also done. In total, 36 TETs (29 thymomas and 7 thymic carcinomas) were analyzed. PD-L1 immunohistochemical staining (Ventana PD-L1 clone SP142) was performed in all cases. The percentage of the positive tumor cells (TC value), the percentage of tumor area occupied by positive immune cells (IC value) was evaluated. Evaluation of PD-L1 expression in tumor cells showed a good reproducibility (κ-value: 0.840; Spearman r=0.966; P<0.0001). About 69% of thymomas (20/29) and 43% of thymic carcinomas (3/7) showed high positivity rate (TC≥50% or IC ≥10%), which may indicate therapeutic advantage similar to nonsmall cell lung cancers defined by the same conditions. PD-L1 expression is common in different epithelial tumors of the thymus, which suggests the potential effectiveness of drugs targeting the PD-1/PD-L1 interactions in these neoplasms.

Cell adhesion molecule profiles, proliferation activity and p53 expression in advanced epithelial ovarian cancer induced malignant ascites-Correlation of tissue microarray and cytology microarray

INTRODUCTION

Peritoneal dissemination accompanied by ascites formation is common in epithelial ovarian cancer (EOC). Adhesion molecules are crucial in metastatic spread and the latter involves epithelial-mesenchymal transition (EMT). This study aimed at: (1) clarifying whether E-cadherin and β-catenin expression and proliferative activity in metastatic ovarian cancer are inter-related; (2) Identifying possible correlations between cell adhesion molecular expression profiles, the proliferative activity and p53 expression of tumor cells and tumor grade and stage; (3) testing the cytology microarray (CMA) technique in analyzing metastasis formation.

MATERIAL AND METHODS

Both tumorous and ascitic samples from 27 EOC patients were examined by using tissue microarray (TMA) and cytology microarray (CMA), respectively. CMA blocks were constructed using cores from each cell block of the ascitic specimens. Expression of E-cadherin, β-catenin, Ki-67 and p53 was immunohistochemically detected both in TMA and CMA blocks.

RESULTS

E-cadherin expression was higher in ascitic cells than in primary tumor cells (p = .294). β-catenin expression was significantly lower in ascitic cells than in primary tumor cells (p = .006). Expression of Ki-67 was lower and expression of p53 was higher in primary tumors than in ascitic cells, for p53 the difference was significant (p = .001). Both Ki-67 and p53 expression elevated significantly in high-grade primary tumor cells and in ascites cells (p = .039, and p = .004, respectively).

CONCLUSION

Epithelial-mesenchymal transition- mesenchymal-epithelial transition is suggested as the best descriptive term for our IHC observations which accompany increased proliferative activity of ascitic cells. The CMA method is an adequate and reliable method for the analysis of ascitic tumor cells disseminating from ovarian malignancies.

Concurrence of chromosome 3 and 4 aberrations in human uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy with a very poor prognosis. The most frequent chromosome aberration in UM is the monosomy of chromosome 3. Previously, we demonstrated that ~50% of UMs express type-I receptor for luteinizing hormone‑releasing hormone (LH-RH-R). The gene encoding LH-RH-R is located in chromosome 4 (location: 4q21.2); however, the occurrence of numerical aberrations of chromosome 4 have never been studied in UM. In the present study, we investigated the abnormalities of chromosome 3 and 4, and the possible correlation between them, as well as with LH-RH-R expression. Forty-six specimens of UM were obtained after enucleation. Numerical aberrations of chromosome 3 and 4 were studied by fluorescence in situ hybridization (FISH). Chromosome 4 was detected in normal biparental disomy only in 14 (30%) samples; however, 32 cases (70%) showed more than 2 signals/nucleus. Monosomy of chromosome 3 could be found in 16 (35%) samples. In 6 specimens (13%), more than 2 copies of chromosome 3 were found, while normal biparental disomy was detected in 24 (52%) samples. Statistical analysis indicated a statistically significant (p<0.05) correlation between the copy number of chromosome 3 and 4. Moreover, moderate difference was revealed in the survival rate of the UM patients with various pathological profiles. No correlation was found between chromosome aberrations and LH-RH-R expression. Our results clearly demonstrate abnormalities in chromosome 3 and 4 and the incidence of the monosomy of chromosome 3 in human UM. In summary, our results provide new incite concerning the genetic background of this tumor. Our findings could contribute to a more precise determination of the prognosis of human UM and to the development of new therapeutic approaches to this malignancy.

Measuring expression levels of small regulatory RNA molecules from body fluids and formalin-fixed, paraffin-embedded samples

MicroRNAs are involved in the regulation of various pathophysiological processes such as immune regulation and cancer. Next-generation sequencing methods enable us to monitor their presence in various types of samples but we need flexible methods for validating datasets generated by high-throughput methods. Here we describe the detailed protocols to be used with our MiRNA Primer Design Tool assay design system. The presented methods allow the flexible design of the oligonucleotides needed for the RT-qPCR detection of any variant of small regulatory RNA molecules from virtually any species. This method can be used to measure miRNA levels from formalin-fixed, paraffin-embedded (FFPE) samples and various body fluids. As an example, we show the results of the hsa-miR-515-3p, hsa-miR-325, and hsa-miR-155 quantification using a specific UPL probe (Universal Probe Library) and a stem-loop RT-qPCR assay. The small nucleolar RNA RNU43 is used as endogenous control for normalization of the results. Urine from healthy pregnant women and FFPE samples from patients diagnosed with colorectal cancer and treated with antibody-based anti-EGFR monotherapy were used as samples.

Correlation among metallothionein expression, intratumoural macrophage infiltration and the risk of metastasis in human cutaneous malignant melanoma

BACKGROUND

The formation of metastases and the efficacy of systemic therapies in cutaneous malignant melanoma (CMM) depend on the characteristics of the tumour cells and the host immune response. Aberrant expression of metallothionein (MT) has been observed in several types of cancers with poor prognoses.

OBJECTIVE

To perform an immunohistochemical study on primary CMM comparing the MT expression of tumours without metastases (n = 23) to that of samples with haematogenous metastases (n = 23) and to examine the correlation between MT staining and immunological markers relevant in CMM progression.

METHODS

The immunohistochemical labelling of different tumour sections was analysed using tissue microarrays for the evaluation of the suitability of this method in future studies.

RESULTS

Our results suggest that MT overexpression is significantly more frequent in primary CMM with haematogenous metastases (P = 0.018) and that the overexpression is independent of the Breslow tumour thickness (R = 0.102, P = 0.501). Interestingly, MT overexpression of the tumour cells was correlated with the presence of tumour-infiltrating CD68(+) macrophages (P = 0.003), a known predictive factor for melanoma progression, thereby suggesting a role for MT in the development of a defective host immune response. Furthermore, the presence of CD163(+) macrophages infiltrating the tumours correlated with metastasis formation (P < 0.001), whereas the presence CD1a(+) dendritic cells surrounding the tumours was associated with a lower risk of haematogenous spread (P = 0.003).

CONCLUSION

Our results demonstrate that MT may represent a suitable prognostic factor that can characterize the metastasising ability of CMM and the tumour-promoting host immune response.

Prognostic relevance of the expressions of CAV1 and TES genes on 7q31 in melanoma

The 7q31 locus contains several genes affected in cancer progression. Although evidences exist regarding its impact on tumorigenesis, the role of genetic alterations and the expressions of locus-related genes are still controversial. Our study aimed to define the 7q31 copy number alterations in primary melanomas, primary-metastatic tumor pairs and cell lines. Data were correlated with clinical-pathological parameters. Genetic data show that 7q31 copy number distribution was heterogeneous in both primary and metastatic tumors. Extra copies were highly accompanied by chromosome 7 polisomy, and significantly increased in primary lesions with poor prognosis. Additionally, we determined the mRNA and protein levels of the locus-related CAV1 and TES genes. TES mRNA level was associated with metastatic location. CAV1 mRNA and protein levels were significantly higher in thicker tumors, however, lack of protein was also observed in a subpopulation of thin lesions. Expressions of CAV1 and TES were not associated with 7q31 alterations. In conclusion, 7q31 amplification can predict unfavorable outcome. Alterations of TES mRNA level may predict the location of metastasis. CAV1 possibly affect the cancer cell invasion.

Determination and validation of off-target activities of anti-CD44 variant 6 antibodies using protein biochips and tissue microarrays

We describe a novel procedure for determination and validation of off-target activities of anti-cluster designation antigen identity 44 (CD44) variant 6 recombinant antibodies by combining two complementary technology platforms; namely UNIchip AV-400, containing a printed serial dilution of CD44 variant 6 and approximately 400 different human proteins, and TISSOMICS, enabling human tissue microarray analysis in high-throughput mode. We have analyzed the performance of two human monoclonal recombinant antibodies directed against CD44 variant 6 protein, BMS 116 and BMS 125, in a blinded study. The antibodies exhibit a clear differentiation with regard to their binding profiles in the two systems. BMS 116 shows a low degree of specificity in the normal human Food and Drug Administration (FDA) tissue panel, which was confirmed by binding to more than 206 proteins on the protein biochip. In contrast, BMS 125 gives a highly selective membranous staining on selected human epithelial tissue components with no off-target activities observed on the protein biochip. Additionally, antibody BMS 125 shows a higher sensitivity to its antigen CD44 variant 6 than antibody BMS 116 as determined by the protein biochip.

Heterogeneity of prostate-specific membrane antigen (PSMA) expression in prostate carcinoma with distant metastasis

Prostate-specific membrane antigen (PSMA) is a transmembrane protein that is overexpressed in advanced stage prostate adenocarcinomas. As a novel target for in vivo prognostic and therapeutic approaches, the distribution pattern of PSMA in primary and metastatic tumors is of significant interest. In this study we addressed the cellular distribution and heterogeneity of PSMA expression. Paraffin-embedded sections of 51 patients with primary prostate carcinoma and distant metastases were evaluated. Immunohistochemistry was used to determine the cellular localization, staining intensity and positive cell fraction which were related to tumor type and growth pattern. We demonstrated differences in the intracellular localization of the PSMA immunostaining which seem to be related to the tumor differentiation pattern. A significant number of the primary tumors (7/51) and metastases (6/51) presented with highly heterogeneous PSMA expression and in further 2 primary, and 8 metastatic tumors the staining was in the negative range (<10% positive tumor cells). A direct correlation between histological parameters and PSMA expression could not be demonstrated. Our findings clearly support the feasibility but also direct to potential failures of PSMA-targeted in vivo diagnostic and therapeutic approaches in prostate cancer patients with distant metastasis.

Seromuscular gastrocystoplasty in dogs

INTRODUCTION

The aim of this study was to investigate the feasibility of seromuscular gastrocystoplasty (SGCP) in an animal model and to compare it to conventional gastrocystoplasty (CGCP).

MATERIALS AND METHODS

CGCP and SGCP (using gastric segments without mucosa) were each performed in 6 dogs. In both procedures, two-thirds of the dome of the bladder were excised and the gastric segment anastomosed to the bladder remnant. Cystography, cystomanometry, measurements of urine pH, and gross and microscopic pathological studies were carried out preoperatively, and postoperatively, at 6 and 12 weeks.

RESULTS

All seromuscular gastric segments proved viable, and 6 weeks after the operation they were covered by a thin layer of transitional epithelium, which had gradually thickened by the end of the 12-week follow-up. There was no difference in bladder capacity and compliance between the two groups, however, fasting urinary pH values were higher (less acidic) in the SGCP group.

CONCLUSIONS

Stripping off the mucosa of the gastric segment appears to stop hydrochloric acid secretion, thereby lessening the possible risk of ulceration, perforation, dysuria-haematuria, metaplasia and malignancy. The uroepithelium overgrowth of the seromuscular gastric segments might provide a more physiological neo-bladder than when using full-thickness gastrocystoplasty.

Disseminated tumor cells in the bone marrow - chances and consequences of microscopical detection methods

The detection of disseminated tumor cells (DTCs) in the hematopoetic system is important for various reasons. It is essential for tumor staging. According to the International Neuroblastoma Staging System (INSS) only the cytomorphological examination of bone marrow smears is accepted despite the fact that an infiltrate below 0.1%, can hardly be detected and even infiltrates of more than 10% are sometimes overlooked. Another important aspect is the monitoring of the disease response to cytotoxic drugs by quantifying DTCs. Moreover, bone marrow aspirates represent an ideal source to determine the genetic and biological make up of DTCs at diagnosis and during follow up. Key issues that can be tested on DTCs are: determination of the proliferation capacity, the apoptotic rate, the drug sensitivity etc. The prerequisite for such a bone-marrow diagnosis, however, is the unequivocal identification of disseminated tumor cells. Thus, in order to avoid false positive and false negative results, which are a risk in bone-marrow diagnostics, a system was developed to distinguish tumor cells from non-neoplastic cells and to facilitate the gain of insights into the biological make-up of tumor cells more easily.

Combined metaphase, interphase cytogenetic, and flow cytometric analysis of DNA content of pediatric acute lymphoblastic leukemia

Eleven pediatric acute lymphoid leukemia patients were investigated for chromosomal aneuploidy by interphase cytogenetics using chromosome specific (peri)centromeric probes for all the somatic and sex chromosomes. Results were compared with metaphase cytogenetic and flow cytometric derived DNA aneuploidy data. Experiments performed on normal human cells using chromosome specific (peri)centromeric probes indicated that disomy could be recognized in a range of 89.1+/-2.7% (12.9)-96.8+/-0.2% (0.9) for the somatic chromosomes and in 98.1+/-0.4% (1.3) for the sex chromosomes. Using the cutoff level of the mean false monosomy and trisomy in the control cells +2 S.D., chromosome loss or gain for the somatic chromosomes could be revealed beyond a clonal ratio of 3.6-13.2% and 1.1-6.8%, respectively. The same value for the sex chromosomes was 3.5% and 0%, respectively. In 5 of 11 patients the leukemic cells proved to be diploid with all three methods at both gross DNA and chromosome levels. Interphase cytogenetics revealed chromosome loss or gain in all of the remaining six patients, however, the metaphase analysis indicated numerical aberration in only two patients. In one of them only the increased chromosome number could have been detected without identifying the chromosomes involved and in the other one the two methods indicated trisomy for a different chromosome. Flow cytometric data showed aneuploidy in three of the six aneuploid leukemia patients. The results suggest that interphase cytogenetics might be more accurate compared with flow cytometry and metaphase analysis to reveal aneuploidy.