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Abstract Ubiquitination involves the attachment of ubiquitin to lysine residues on substrate proteins or itself, which can result in protein monoubiquitination or polyubiquitination. Ubiquitin attachment to different lysine residues can generate diverse substrate-ubiquitin structures, targeting proteins to different fates. The mechanisms of lysine selection are not well understood. Ubiquitination by the largest group of E3 ligases, the RING-family E3 s, is catalyzed through co-operation between the non-catalytic ubiquitin-ligase (E3) and the ubiquitin-conjugating enzyme (E2), where the RING E3 binds the substrate and the E2 catalyzes ubiquitin transfer. Previous studies suggest that ubiquitination sites are selected by E3-mediated positioning of the lysine toward the E2 active site. Ultimately, at a catalytic level, ubiquitination of lysine residues within the substrate or ubiquitin occurs by nucleophilic attack of the lysine residue on the thioester bond linking the E2 catalytic cysteine to ubiquitin. One of the best studied RING E3/E2 complexes is the Skp1/Cul1/F box protein complex, SCFCdc4, and its cognate E2, Cdc34, which target the CDK inhibitor Sic1 for K48-linked polyubiquitination, leading to its proteasomal degradation. Our recent studies of this model system demonstrated that residues surrounding Sic1 lysines or lysine 48 in ubiquitin are critical for ubiquitination. This sequence-dependence is linked to evolutionarily conserved key residues in the catalytic region of Cdc34 and can determine if Sic1 is mono- or poly-ubiquitinated. Our studies indicate that amino acid determinants in the Cdc34 catalytic region and their compatibility to those surrounding acceptor lysine residues play important roles in lysine selection. This may represent a general mechanism in directing the mode of ubiquitination in E2 s.

Breast cancer is one of the leading causes of cancer-related mortality in women. During tumor growth, periods of hypoxia are followed by reoxygenation due to neovascularisation leading to disturbed redox homeostasis. ROS (Reactive Oxygen Species) produced under hypoxia activate HIF1α. ROS can also activate the major antioxidant transcription factor NRF2, but also cause damage to biomolecules. Lipids are susceptible to peroxidation, as evidenced by the formation of reactive aldehydes, among which, HNE (4-hydroxynonenal) is the most studied one. Knowing that HIF1α (Hypoxia Inducing Factor 1α) is associated with breast cancer malignancy, we aimed to investigate its correlation with HNE and NRF2 (Nuclear factor erythroid 2-related factor 2). Our results show that HIF1α is activated in breast cancer, indicating an increase in ROS but not followed by HNE production. On the other hand, NRF2 was increased in all types of breast cancer suggesting that oxidative stress is present in these pathologies, but also supporting HIF1α. Interestingly, NRF2 was activated in HER2 positive and TNBC, indicating the role of stromal NRF2 in breast cancer malignancy., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ana Cipak Gasparovic reports financial support was provided by Croatian Ministry of Science and Technology., (Copyright © 2023 Elsevier GmbH. All rights reserved.)

The most common nonmelanoma skin cancers (NMSC) are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). The incidence of NMSC is 18-20 times higher than the incidence of melanoma. The Cyclooxygenase-2 (COX-2) and Matrix Metalloproteinase-1 (MMP-1) enzymes have both been linked to the development of these diseases but their exact significance is unknown. We conducted a retrospective analysis on 148 adult patients with cutaneous BCC and SCC. Cases were divided according to the sub-types of BCC and the degree of SCC differentiation. Immunohistochemical staining for COX-2 and MMP-1 was performed and analyzed to determine if the expression of these biomarkers were associated with BCC subtypes and the degree of SCC. differentiation. We did not find a significant association of the level of differentiation of SCC with the immunohistochemical expression for MMP-1 or COX-2. There was a significant association between BCC subtypes and immunohistochemical expression for MMP-1; positive expression of this enzyme reduces the odds for the infiltrative subtypes by 90%. A marginally significant association between BCC subtypes and immunohistochemical expression for COX-2 was also found. This enzyme was highly expressed in non-infiltrative basal cell carcinoma types (94%) compared with infiltrative types (71%). In conclusion, we did not find a significant predictor for SCC expression levels for either of two biomarkers, while the expression of MMP-1 in BCC was significantly inversely associated with the infiltrative type (moderate sensitivity and high specificity). Further research with larger sample sizes is needed to precisely determine the role these enzymes have in these diseases.

Triple-negative breast cancer (TNBC) occurs in around one-sixth of all breast cancer (BC) patients, with the most aggressive behavior and worst prognosis of all BC subtypes. It is a heterogeneous disease, with specific molecular characteristics and natural dynamics of early recurrence and fast progression. Due to the lack of biomarkers or any valid treatment targets, it can only be treated with classic cytotoxic chemotherapy. We analyzed a cohort of 152 patients, median age 58 years, diagnosed with and treated for early stage TNBC at the University Hospital for Tumors, Sestre milosrdnice University Hospital Centre, Zagreb, Croatia, during the 2009-2012 period. Patients were treated with primary surgical approach, adjuvant chemotherapy and adjuvant irradiation. We observed a relatively large proportion of locally advanced TNBC at diagnosis, with large tumor size and nodal involvement, with high grade and high proliferation index Ki67. Patient age, tumor size and lymph node involvement, as expected, were significant and clinically most important prognostic factors for 5-year disease-free survival (67%; 95% CI 60%-75%) and overall absolute survival rate (74%; 95% CI 66%-81%).

The aim was to determine immunohistochemical expression of NEDD9 protein in head and neck squamous cell carcinoma (HNSCC) and the possible relation of its expression with primary tumor size (T), regional lymph node status (N), stage of disease (TNM) and survival period. A total of 131 patients with primary tumor localization in the area of oropharynx, hypopharynx and larynx, monitored for at least 5 years after initial surgical treatment were analyzed. The study included 128 male and three female patients, median age 62.0 (range 53.0-68.0) years. Of these, 105 (95%) patients showed positive NEDD9 expressed by dyed cytoplasm. There were no significant differences in NEDD9 expression according to TNM tumor status. Patients with positive NEDD9 expression had a significantly higher median (IQR) survival time 51.0 (15.0-60.0) months as compared to 22.5 (9.0-55.0) months in patients with negative NEDD9 expression (p=0.048). NEDD9 negative expression, controlled for the influence of other variables included in the Cox's proportional hazards model, had a significant hazard ratio (HR) of 2.10 (95% CI: 1.23-3.58; p=0.006). The results of our study showed that NEDD9 expression might be an independent prognostic marker in patients with HNSCC regarding data on overall survival and mortality.

Primary malignant melanoma of the urinary bladder is rare, with only 20 cases reported to date. We present a case of an 87-year-old woman with multiple comorbidities who presented with advanced urinary bladder neoplasm. Histopathologic analysis suggested melanoma of the urinary bladder. No previous or concurrent diagnosis of cutaneous melanoma was documented. The patient underwent transurethral resection of the tumor before and during hospitalization at our hospital but died shortly after due to widespread disease. Autopsy was not performed.

Multielemental analysis of whole blood can provide significant information for the evaluation of nutritional status and diagnosis of certain diseases as well as for the assessment of exposure to potentially toxic metals. However, the quantification of multiple elements in whole blood is not easy partly because of the wide variation in element concentrations (from ng L -1 to g L -1 ) and the complex matrix. The aim of this work was to develop a fast, sustainable, and reliable analytical method, in combination with low-power TXRF, for multielemental analysis of blood samples. Firstly, a set of experiments were carried out to select the best diluent type and dilution factor using the control material SeronormTM Trace Elements Whole Blood L-1. A critical evaluation of the parameters affecting the sample deposition on the reflector was also carried out including a study of the shape and element distribution of the deposited residue on the reflector by micro X-ray fluorescence spectrometry. Using the best analytical conditions, limits of detection estimated were in the low milligrams per kilogram range and similar to those obtained using more complex sample treatments such as digestion. Accuracy and precision of the results were in most cases acceptable (recoveries 89-102%, RSD 6-8%, n = 5). Only underestimated values were obtained for light elements such as potassium. To prove the applicability of the method, several blood samples from control and thyroid disease patients were analyzed. Despite the fact that more samples need to be analyzed, it seems that Zn and Br contents in some of the patients are significantly higher compared to control samples. Graphical abstract.

Background: Proliferation rate is a major determinant of the biologic behavior of the tumor and provides information that can be used to guide treatment decisions., Methods: This ring study included 27 pathologists from 14 Institutions, in order to assess inter-observer concordance between pathologists in Croatia. We analyzed Ki-67 proliferative index on ten randomly selected breast cancer samples comparing consistency between visual assessment using light microscopy compared to digital image analyses results from one central laboratory as a referral value., Results: When we analyzed Ki-67 as numeric value high concordance rate was found between Ki-67 score visually assessed in all participating Institutions compared to referral value assessed by digital image analysis (ICC 0.76, 95% CI 0.58-0.91), and Krippendorff's alpha was 0.79 (95% CI 0.58-1.00). Concordance was better in slides with higher Ki-67 values. When we categorized Ki-67 values according to generally accepted 20% cut-off value we noticed the lower concordance rate among participants in our study., Conclusion: Proliferation remains one of the most important parameters for tumor characterization helpful in making clinical decisions, but it should be used with great caution. Standardization of the Ki-67 assessment is essential and proliferating index should be expressed as exact numeric value. For patients with proliferative index near the cut-off value, other factors must be considered in making clinical decisions.

Introduction: The aim of this case report was to discuss an extremely rare oral lesion as a result of primary pulmonary tuberculosis., Case Report: In this case report, the patient with refractory painless ulceration at ventral surface of the tongue was described. Detailed medical history was taken followed by clinical examination of the oral mucosa and palpation of regional lymph nodes. Clinical examination revealed ulceration on the patient's ventro-lateral surface of the tongue, approximately two centimeters in diameter. Palpation of regional lymph nodes has not revealed enlargement. The toluidine blue test of the suspected lesion was performed at each control examination. Biopsy samples for histopathologic diagnosis were taken three times. The analysis of the first biopsy sample for histopathology revealed a non-specific inflammation, the second biopsy revealed a caseous necrosis without positive Ziehl-Neelsen staining and the third biopsy revealed a granulomatous inflammation which was highly suspicious of sarcoidosis. During hospitalization, the patient underwent a complete physical examination, and laboratory and radiological diagnostics. Physical chest examination revealed bilaterally coarse crepitations and laboratory findings of his complete blood count revealed normocytic anemia of chronic disease. Radiographic examination of lungs showed multiple small nodules bilaterally and positive direct sputum smear., Conclusion: Although oral tuberculosis is a rare condition, it must be taken into account in differential diagnosis of refractory painless oral ulcers., Competing Interests: Conflict of interest: Authors declare they have no conflict of interest.

Since the incidence of cancer has increased over the years, adequate prevention programmes are needed. Thyroid cancer is one of the fastest growing cancer types in the world. In this study we performed a case-control study of 100 untreated patients with thyroid diseases (papillary thyroid cancer, follicular thyroid adenoma, and other thyroid diseases) and 100 control volunteers. Oxidative status differed among the two investigated groups. The patients' group had 1.60-fold higher concentrations of malondialdehyde and 1.26-fold higher concentrations of protein carbonyls. At the same time, the concentrations of glutathione and catalase activity were by 32% and 35% lower, respectively. A similar effect was observed for the cytogenetic status where higher comet assay tail intensity (1.84-fold) and the total numbers of chromosome aberrations (1.47-fold), micronuclei (2.32-fold), nucleoplasmic bridges (3.98-fold), and nuclear buds (2.34-fold) were detected. As for protein expression in thyroid tissue, 97.89% were positive for either B-Raf or Ret. Interestingly, the papillary thyroid cancer patients more frequently expressed B-Raf proteins compared to the follicular thyroid adenoma patients and patients with other thyroid diseases. Human biomonitoring studies enable a risk assessment of general population, such data could be used to identify risk subgroups., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Expression of Breast Cancer Metastasis Suppressor 1 (BRMS1) reduces the incidence of metastasis in many human cancers, without affecting tumorigenesis. BRMS1 carries out this function through several mechanisms, including regulation of gene expression by binding to the mSin3/histone deacetylase (HDAC) transcriptional repressor complex. In the present study, we show that BRMS1 is a novel substrate of Cyclin-Dependent Kinase 2 (CDK2) that is phosphorylated on serine 237 (S237). Although CDKs are known to regulate cell cycle progression, the mutation of BRMS1 on serine 237 did not affect cell cycle progression and proliferation of MDA-MB-231 breast cancer cells; however, their migration was affected. Phosphorylation of BRMS1 does not affect its association with the mSin3/HDAC transcriptional repressor complex or its transcriptional repressor activity. The serine 237 phosphorylation site is immediately proximal to a C-terminal nuclear localization sequence that plays an important role in BRMS1-mediated metastasis suppression but phosphorylation does not control BRMS1 subcellular localization. Our studies demonstrate that CDK-mediated phosphorylation of BRMS1 regulates the migration of tumor cells.

Objective: The identification of myoepithelial cells (MEC) is a valuable clue in the differential diagnosis of breast lesions. A series of breast lesions with occasional absence of or decrease in the staining for some MEC markers was analyzed for the expression of a novel marker, p40, and results were compared to the p63 staining profile., Methods: Samples (n = 34) from patients with benign sclerosing lesions (n = 11), ductal carcinoma in situ (n = 13) and adenomyoepithelial lesions (n = 10) and associated normal breast tissues (n = 31) were selected to evaluate the differential expression of p40 and p63 using immunohistochemistry. Triple-negative, cytokeratin 5 (CK5)-expressing invasive breast carcinomas (n = 19) were also assessed for p40 expression., Results: Normal structures showed similar diffuse and strong MEC positivity using p40 and p63 in all 31 cases. The two antibodies performed similarly in all 34 breast lesions acknowledged to present altered expression of MEC markers; focal losses of expression occurred in a parallel fashion. CK5-positive carcinomas expressed p40 more frequently than p63 (18/19 vs. 8/19) and the staining was more marked., Conclusions: It seems that both antibodies can be used interchangeably for MEC identification, but show differences in the labeling at least in a subset of tumor cells in triple-negative carcinomas., (© 2015 S. Karger AG, Basel.)

Thyroid cancer is one of the fastest growing cancer types worldwide. Using the cytokinesis-block micronucleus (CBMN) and comet assays, we performed a case-control study of 23 untreated papillary thyroid cancer (PTC) patients and 23 healthy volunteers. PTC patients showed higher basal DNA damage in peripheral blood lymphocytes. The CBMN assay indicated that the numbers of micronuclei, nuclear buds, and nucleoplasmic bridges among the cases were 2.67-, 2.79-, and 7.72-fold higher, respectively, than among the controls (p < 0.05). Comet assay tail lengths and tail intensities were 1.20- and 1.94-fold higher, respectively (p < 0.05). In additional, 14 thyroid tissues from PTC patients were probed for Raf-B and Ret expression; all samples were positive for at least one of these proteins., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The attachment of ubiquitin (Ub) to lysines on substrates or itself by ubiquitin-conjugating (E2) and ubiquitin ligase (E3) enzymes results in protein ubiquitination. Lysine selection is important for generating diverse substrate-Ub structures and targeting proteins to different fates; however, the mechanisms of lysine selection are not clearly understood. The positioning of lysine(s) toward the E2/E3 active site and residues proximal to lysines are critical in their selection. We investigated determinants of lysine specificity of the ubiquitin-conjugating enzyme Cdc34, toward substrate and Ub lysines. Evaluation of the relative importance of different residues positioned -2, -1, +1 and +2 toward ubiquitination of its substrate, Sic1, on lysine 50 showed that charged residues in the -1 and -2 positions negatively impact on ubiquitination. Modeling suggests that charged residues at these positions alter the native salt-bridge interactions in Ub and Cdc34, resulting in misplacement of Sic1 lysine 50 in the Cdc34 catalytic cleft. During polyubiquitination, Cdc34 showed a strong preference for Ub lysine 48 (K48), with lower activity towards lysine 11 (K11) and lysine 63 (K63). Mutating the -2, -1, +1 and +2 sites surrounding K11 and K63 to mimic those surrounding K48 did not improve their ubiquitination, indicating that further determinants are important for Ub K48 specificity. Modeling the ternary structure of acceptor Ub with the Cdc34~Ub complex as well as in vitro ubiquitination assays unveiled the importance of K6 and Q62 of acceptor Ub for Ub K48 polyubiquitination. These findings provide molecular and structural insight into substrate lysine and Ub K48 specificity by Cdc34.