Cancer stem cells (CSCs), known also as tumor-initiating cells, are quiescent, pluripotent, self-renewing neoplastic cells that were first identified in hematologic tumors and soon after in solid malignancies. CSCs have attracted remarkable research interest due to their role in tumor resistance to chemotherapy and radiation treatment as well as recurrence. Extensive research has been devoted to the role of CSCs in glioblastoma multiforme (GBM), the most common primary brain tumor in adults, which is characterized by a dismal prognosis because of its aggressive course and poor response to treatment. The aim of the current paper is to provide an overview of current knowledge on the role of cancer stem cells in the pathogenesis and treatment resistance of glioblastoma. The six regulatory mechanisms of glioma stem cells (GSCs)—tumor microenvironment, niche concept, metabolism, immunity, genetics, and epigenetics—are reviewed. The molecular markers used to identify GSCs are described. The role of GSCs in the treatment resistance of glioblastoma is reviewed, along with future treatment options targeting GSCs. Stem cells of glioblastoma thus represent both a driving mechanism of major treatment difficulties and a possible target for more effective future approaches.

HIV-induced immune suppression results in the high prevalence of HIV/AIDS-associated malignancies including Kaposi sarcoma, non-Hodgkin lymphoma, and cervical cancer. HIV-infected people are also at an increased risk of “non-AIDS-defining” malignancies not directly linked to immune suppression but associated with viral infections. Their incidence is increasing despite successful antiretroviral therapy. The mechanism behind this phenomenon remains unclear. Here, we obtained daughter clones of murine mammary gland adenocarcinoma 4T1luc2 cells expressing consensus reverse transcriptase of HIV-1 subtype A FSU_A strain (RT_A) with and without primary mutations of drug resistance. In in vitro tests, mutations of resistance to nucleoside inhibitors K65R/M184V reduced the polymerase, and to nonnucleoside inhibitors K103N/G190S, the RNase H activities of RT_A. Expression of these RT_A variants in 4T1luc2 cells led to increased production of the reactive oxygen species (ROS), lipid peroxidation, enhanced cell motility in the wound healing assay, and upregulation of expression of Vimentin and Twist. These properties, particularly, the expression of Twist, correlated with the levels of expression RT_A and/or the production of ROS. When implanted into syngeneic BALB/C mice, 4T1luc2 cells expressing nonmutated RT_A demonstrated enhanced rate of tumor growth and increased metastatic activity, dependent on the level of expression of RT_A and Twist. No enhancement was observed for the clones expressing mutated RT_A variants. Plausible mechanisms are discussed involving differential interactions of mutated and nonmutated RTs with its cellular partners involved in the regulation of ROS. This study establishes links between the expression of HIV-1 RT, production of ROS, induction of EMT, and enhanced propagation of RT-expressing tumor cells. Such scenario can be proposed as one of the mechanisms of HIV-induced/enhanced carcinogenesis not associated with immune suppression.

Background and Objective. Distinction between benign and malignant thyroid tumors is essential for proper clinical management. The aim of this study was to evaluate the diagnostic potential of a set of 3 molecular markers in the differential diagnosis of thyroid tumors. Material and Methods. Immunohistochemistry for HBME-1, E-cadherin (E-CAD), and CD56 was carried out in 36 follicular adenomas, 77 colloid goiters, 36 papillary thyroid carcinomas, and 14 follicular carcinomas. Sixty-eight thyroid fine needle aspiration (FNA) cases confirmed by subsequent surgical resection specimens were selected. Immunocytochemistry for HBME-1, E-CAD, and CD56 was performed in these cases, including 25 papillary thyroid carcinomas, 1 follicular carcinoma, 22 follicular adenomas, and 20 colloid goiters. Results. PTC was characterized by a decreased expression of E-CAD and CD56 contrary to the surrounding benign thyroid tissues. There was no HBME-1 expression in benign thyroid tissues, but it was high in papillary thyroid carcinomas and weak in follicular adenomas. The expression of E-CAD and CD56 was significantly higher in follicular adenomas than in the surrounding thyroid tissues. Analyzing the FNA material, HBME-1 expression was documented in 96% of papillary thyroid carcinomas, but there was no expression in the benign lesions. E-CAD and CD56 expression was significantly weakened in papillary thyroid carcinomas, but enhanced in follicular adenomas. Conclusions. HBME-1 was found only in malignant lesions and can be considered the most sensitive, specific single marker in papillary thyroid carcinomas. CD56 and E-CAD can assist in the decision-making on the benign and malignant nature of the nodule. Immunocytochemistry is of value as an ancillary test to enhance the diagnostic accuracy of thyroid FNA samples.

Purpose Parathyroid carcinoma (PC) is remarkable for its rare occurrence and challenging diagnostics. PC accounts for 0.1-5 % cases of primary hyperparathyroidism (PHPT). The differentiation from benign tumours is difficult even by morphological criteria. To address these issues, we assessed the PC frequency in two separate European PHPT cohorts and evaluated the demographic, clinical, morphological and molecular background. Methods A retrospective study was carried out, using continuously maintained database (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014) of PHPT patients from two tertiary referral university hospitals in Europe. The demographic, clinical data and frequency of PC among surgically treated PHPT was detected. Immunohistochemistry (IHC) was performed to detect parafibromin, representing protein product of HRPT2 gene and proliferation marker Ki-67. Results Both PHPT cohorts were characterised by close mean age values (58.6 and 58.0 years) and female predominance. The frequency of PC differed significantly between the cohorts: 2.1 vs. 0.3 %; p=0.004. PC was characterised by invariable complete loss of parafibromin contrasting with parathyroid adenomas. The proliferation fraction was similar in both PC cohorts (10.6 and 11.0 %). PC showed significantly higher proliferation fraction than typical parathyroid adenomas (1.6 %), atypical adenomas (1.6 %) or adenomas featuring focal loss of parafibromin (2.2 %). Conclusions PC frequency can range significantly between the two European cohorts. The differences can be attributable to selection bias of patients referred for surgery and are not caused by discordant definition of malignant parathyroid histology. Diffuse loss of parafibromin and increased proliferation fraction by Ki-67 are valuable adjuncts in PC diagnostics due to significant differences with various clinical and morphological subtypes of adenoma.

The panel consisting of three markers, HBME-1, E-CAD and CD56, can be recommended as an adjunct to morphology criteria. HBME-1 is found in malignant lesions only and is the most sensitive and specific single marker in PTC. Decreased expression of E-CAD and CD56 distinguishes PTC from FA and FC. Both FA and FC are characterised by high expression of E-CAD and CD56. The practical use of Ki-67 is difficult due to low values. The role of adhesion factors in thyroid malignancies may be superior in comparison with cell proliferation.

Background: Inflammation plays an important albeit dual role in carcinogenesis. Survival studies have highlighted the prognostic significance of peritumorous inflammation. Currently, the theoretical background allows inflammation, epithelial mesenchymal transition (EMT) and the closely associated stem cell differentiation in colorectal carcinoma (CRC) to be linked. However, there is scarce direct morphological evidence. Purpose and methods: The aim of our study was to investigate the role of inflammation in cancer growth and invasion by analyzing the association between inflammation and known morphological prognostic features of colorectal cancer, EMT, stemness and mismatch repair (MMR) protein expression. The study was designed as a retrospective morphological and immunohistochemical assessment of 553 consecutive cases of surgically treated primary CRC. Results: There were statistically significant associations between high-grade inflammation and lower pT (p = 0.002), absence of lymph node metastases (p < 0.001) and less frequent lymphatic (p = 0.003), venous (p = 0.017), arterial (p = 0.012), perineural (p = 0.001) and intraneural (p = 0.01) invasion. In contrast, Crohn's like reaction (CLR) by density of lymphoid follicles in the invasive front lacked significant differences in regard to pT, pN, tumor invasion into surrounding structures (blood or lymphatic vessels, nerves), grade or necrosis (all p > 0.05). The expression of E-cadherin, CD44 and MMR proteins yielded no statistically significant associations with peritumorous inflammation by Klintrup-Mäkinen score or the density of lymphoid follicles. Nevertheless, E-cadherin levels were significantly associated with the density of eosinophils (p = 0.007). Conclusion: High-grade peritumorous inflammation is associated with beneficial morphologic CRC features, including less frequent manifestations of invasion, and is not secondary to tissue damage and necrosis. CLR is not associated with cancer spread by pTN; this finding indirectly suggests an independent role of CLR in carcinogenesis. Further, inflammation by Klintrup-Mäkinen grade and CLR is not dependent on epithelial-mesenchymal transition and stem cell differentiation. Our study highlights the complex associations between inflammation, tumor morphology, EMT, stemness and MMR protein expression in human CRC tissues.

We would like to present a patient with a classical phenotype of a rare disorder - Cowden syndrome, its diagnostics and management challenges. A breast surgeon has to be aware of this rare condition when treating a patient with breast manifestations of Cowden syndrome and has to refer the patient to a clinical geneticist for further evaluation. Sequencing of the PTEN gene showed the Asp24Gly mutation. According to the latest literature data, the lifetime risk of breast cancer for Cowden syndrome patients is 81% and surgery is a justified option to reduce the risk of breast cancer. Bilateral risk-reducing mastectomy with immediate reconstruction was performed to eliminate further risk of breast cancer. 3 years after the risk-reducing breast surgery the patient is satisfied with the outcome. This is to our best knowledge the first reported Cowden syndrome case with follow-up data after risk-reducing measures have been taken.

The study represents a comprehensive retrospective morphological and immunohistochemical profiling of pancreatic neuroendocrine neoplasms (PNENs) in order to reveal the associations between morphological and molecular parameters. The local tumour spread (T), presence of metastases in regional lymph nodes (N) and distant organs (M), tumour grade (G) and resection line status (R) by pathology findings (pTNMGR), mitotic activity, perineural, vascular and lymphatic invasion were assessed in 16 surgically resected PNENs. By immunohistochemistry, expression of Ki-67, p53, p27, p21, cyclin D1, Bcl-2, E-cadherin, CD44, vimentin, cyclooxygenase 2 (COX-2), microvascular density, and cytokeratin (CK) spectrum, along with neuroendocrine, intestinal and squamous markers were detected. Descriptive statistics, Chi-square test, Spearman's rank correlation, Mann-Whitney and Kruskal-Wallis methods were applied; p < 0.05 was considered significant. Ki-67, CK19, p63, vimentin and COX-2 were significantly up-regulated in PNENs in comparison to benign pancreatic islets. A complex network of morphological and molecular associations was identified. Ki-67 correlated with PNEN size (p = 0.022), the World Health Organization 2004 and 2010 classification grades (p = 0.021 and p = 0.002), stage (p = 0.028) and mitotic count (p = 0.007) but among molecular markers -with CK19 (p = 0.033) and vimentin (p = 0.045). CK19 was significantly up-regulated in PNENs, having higher pT (p = 0.018), pR (p = 0.025), vascular (p = 0.020), perineural (p = 0.026) and lymphatic invasion (p = 0.043). In conclusion, proliferation activity (by Ki-67), E-cadherin, vimentin and CK19 are important molecular characteristics of PNENs due to significant associations with morphological tumour characteristics, pTNMGR and invasive growth.