Krzysztof Helewski

Role of Notch signaling pathway in gastric cancer pathogenesis

Notch signaling pathway is activated dynamically during evolution playing significant role in cell fate determination and differentiation. It has been known that alterations of this pathway may lead to human malignancies, including gastric cancer. Despite a decline in the overall incidence, this disease still remains an important global health problem. Therefore, a better understanding of the molecular alterations underlying gastric cancer may contribute to the development of rationally designed molecular targeted therapies. It has been reported that Notch1 receptor could become a prognostic marker of gastric cancer and novel target for gastric cancer therapy. Among the novel and targeted approaches for the treatment of gastric cancer is also the process of Notch receptors regulation by specific microRNA. γ-secretase inhibitors are also taken into consideration.

The Notch ligand Delta-like 4 (DLL4) as a target in angiogenesis-based cancer therapy?

Angiogenesis is a complex multistep process by which new capillary structures arise from pre-existing vessels in response to angiogenic stimuli. This process plays a key role during tumorigenesis because the vascular network within the tumor enables malignant cells to establish distant metastases. Thus, it is not surprising that targeting tumors with angiogenesis-based therapy remains a significant area of preclinical and clinical studies. One of the most prominent factors considered as a promising target in such therapy is the Notch ligand Delta-like 4 (DLL4). Emerging evidence suggests that blockade of DLL4 in tumors results in excessive but non-productive angiogenesis which affects tumor growth, even in tumors which are insensitive to anti-VEGF therapy. Nevertheless, the careful evaluation of adverse effects on normal organs’ physiology in relation to therapeutic doses of DLL4 inhibitors will be critical for advancement of DLL4 blocking agents in clinical practice.

Tissue Factor and Tissue Factor Pathway Inhibitor in Chronically Inflamed Gallbladder Mucosa

We characterised a tissue factor (TF) and tissue factor pathway inhibitor (TFPI) expression in relation to severity of inflammatory infiltration of the gallbladder mucosa in a chronic cholecystitis. We prospectively studied the gallbladder specimens obtained from 54 patients who had undergone cholecystectomy due to chronic calculous cholecystitis and 16 calculosis-free gallbladder specimens obtained from patients who underwent cholecystectomy due to the polyp/polyps as well as in cases of gallbladder injury. To assess TF and TFPI immunoreactivity by immunohistochemistry, the monoclonal anti-human TF and TFPI antibodies were used. The inflammatory infiltration of the gallbladder mucosa was reflected by the number of CD3 and CD68 positive cells. The expression of TF and TFPI differed significantly between the cholecystitis and the control group. Most capillary endothelial cells of the cholecystitis group presented weak expression for TFPI. The mean number of CD3 positive lymphocytes in the cholecystitis group was 18.6 ± 12.2, but the mean number of CD68 positive cells was 29.7 ± 13.9. In the control sections, it was 3.1 ± 1.9 and 8.8 ± 3.9, respectively (P < 0.001). The results of the current study suggest that the tissue procoagulant state found may be engaged in the etiopathogenesis of the cholecystitis.

Therapeutic Window for Calcium-Channel Blockers in the Management of Dilated Cardiomyopathy: A Prospective, Two-Centre Study on Non-Advanced Disease

Objective: This study aimed to investigate the usefulness of the calcium-channel blocker verapamil in non-advanced dilated cardiomyopathy (DCM). Methods: This was a randomised trial of 70 DCM patients treated with carvedilol (36 patients) and verapamil (instead of β-blocker; 34 patients) for 12 months. The remaining heart failure (HF) therapy was constant in both groups. The primary outcomes were to determine selected echocardiography parameters and functional status of patients. The secondary outcome included death, heart transplantation and re-hospitalisation due to HF progression. Results: Of the primary outcomes, only the mean ratio of early to late transmitral flow velocities increased significantly in the verapamil-treated patients as compared with the carvedilol-based therapy (1.1 ± 0.3 vs. 0.7 ± 0.2; 95% CI –0.6 to –0.1; p = 0.015). Simultaneously, the Minnesota Quality of Life improved significantly in the verapamil group (95% CI 5.2–19.9; p = 0.002). It was accompanied by the favourable effect of verapamil therapy on exercise capacity in the 6-min walk test (95% CI 21.3–110.7; p = 0.005). Conclusion: The addition of verapamil to angiotensin-converting enzyme and aldosterone inhibitors in non-advanced DCM patients has been shown to have a neutral or even positive effect in a few patients.

Immunohistochemical assessment of mitochondrial superoxide dismutase (MnSOD) in colorectal premalignant and malignant lesions

Introduction It is generally accepted that mitochondria are a primary source of intracellular reactive oxygen species (ROS). Under physiological circumstances they are permanently formed as by-products of aerobic metabolism in the mitochondria. To counter the harmful effect of ROS, cells possess an antioxidant defence system to detoxify ROS and avert them from accumulation at high concentrations. Mitochondria-located manganese superoxide dismutase (MnSOD, SOD2) successfully converts superoxide to the less reactive hydrogen peroxide (H2O2). To the best of our knowledge, there are no available data regarding immunohistochemical expression of MnSOD in colorectal neoplastic tissues. Aim To investigate the immunohistochemical expression status of MnSOD in colorectal premalignant and malignant lesions. Material and methods This study was performed on resected specimens obtained from 126 patients who had undergone surgical resection for primary sporadic colorectal cancer, and from 114 patients who had undergone colonoscopy at the Municipal Hospital in Jaworzno (Poland). Paraffin-embedded, 4-µm-thick tissue sections were stained for rabbit polyclonal anti SOD2 antibody obtained from GeneTex (clone TF9-10-H10 from America Diagnostica). Results Results of our study demonstrated that the development of colorectal cancer is connected with increased expression of MnSOD both in adenoma and adenocarcinoma stages. Samples of adenocarcinoma with G2 and G3 grade showed significantly higher levels of immunohistochemical expression of this antioxidant enzyme. Moreover, patients with the presence of lymphovascular invasion and higher degree of regional lymph node status have been also characterised by higher levels of MnSOD expression. The samples of adenoma have been characterised by higher levels of MnSOD expression in comparison to normal mucosa as well. Interestingly, there was no significant correlation between expression and histological type of adenoma. Conclusions Development of colorectal cancer is connected with increased expression of MnSOD both in adenoma and adenocarcinoma stages.

Response to Dual Antiplatelet Therapy Does Not Impact Bleeding Risks in Patients Undergoing Oral Surgery after Acute Coronary Syndromes

Introduction: Oral surgery (OS) in patients on antecedent dual antiplatelet therapy (DAPT) may be associated with extra bleeding risks. Monitoring platelet activity in such patients may be beneficial for safety when performing OS. Objectives: The aim of this study was to assess whether platelet function during DAPT impacted the risk of bleeding following OS in patients with acute coronary syndromes (ACS). Patients and Methods: Patients who required OS on top of DAPT with aspirin and clopidogrel (n = 55) for invasively treated ACS were included. The control group (n = 33) consisted of patients who underwent OS with no antiplatelet agent. Platelet aggregation before OS was assessed with a Multiplate® analyzer. Bleeding during OS and at days 1, 3, 7 and 10 after surgery was serially evaluated. Results: All 88 patients completed the study. An incomplete response to aspirin or clopidogrel was observed in 43.6% of the patients. In 11% of the cases, an excessive response to clopidogrel was demonstrated. No excessive bleeding upon OS was exhibited in either group during the entire follow-up. Platelet aggregation values and the use of DAPT did not impact the performance of OS. Conclusion: Therapy with clopidogrel and aspirin after ACS does not seem to increase the risk of real-life bleeding following OS, regardless of the platelet activity response to DAPT.

Tissue hemostasis and chronic inflammation in colon biopsies of patients with inflammatory bowel disease.

Inflammatory bowel disease (IBD) is characterized by a chronic inflammation accompanied by procoagulation settings. However, tissue hemostasis in IBD patients was only incidentally reported. Accordingly, the current study characterizes changes in tissue hemostasis components in a colon inflammatory setting. Serial cryostat sections of endoscopic mucosal biopsy specimens taken from 26 consecutive IBD patients diagnosed de novo and normal colon resection specimens taken from 6 patients were immunohistochemically stained with monoclonal anti-human tissue factor (TF), tissue factor pathway inhibitor (TFPI), thrombomodulin (TM), as well as CD3 and CD68 positive cells. The hemostatic components studied differed significantly from the control subjects. Up-regulation predominated in the case of TF while down-regulation was mainly found in TM and TFPI in IBD. In the control sections, TF was observed in a few fibroblast-shaped cells in the lamina propria, while in the majority of IBD sections, TF positively stained small microvessels, infiltrating mononuclear cells and fibroblast-shaped cells tightly surrounding the colon crypts. Thrombomodulin intensively stained the endothelium of the small capillary vessels in the control, whereas such staining mainly accompanied infiltrating mononuclear cells of the IBD subjects. Tissue factor pathway inhibitor positively stained the endothelium of the small capillary vessels in the control group, whereas in the IBD group endothelial cells presented only weak TFPI staining. The mean number of CD3-positive lymphocytes in IBD was 23.3 ± 14.3, but the mean number of CD68-positive cells was 114.5 ± 55.8. In the control sections, it was 4.1 ± 2.4 and 39.6 ± 17.9, respectively. There was no relationship between CD3 and CD68 (+) cells and the hemostasis markers studied. The results of the current study indicate a shift of tissue hemostasis toward the procoagulant state irrespective of the severity of inflammatory infiltration. In addition, TF distribution in the colon sections of IBD patients may indicate a role in the restoration of the barrier function in injured intestinal mucosa.

Angiogenesis in primary hyperparathyroidism

Angiogenesis can be described as a formation of new vessels from the existing microvasculature and is a process of great importance to the tumor development. Parathyroid tissue can trigger spontaneous induction of angiogenesis in vitro and in vivo models in a vascular endothelial growth factor (VEGF)-dependent manner. Autotransplantated parathyroid tissue after thyroidectomy is able to form new vasculature and produce parathormone, maintaining calcium homeostasis. A great amount of factors contributes to the process of new vessel formation in primary hyperparathyroidism, such as VEGF, transforming growth factor β, and angiopoietins. Studies demonstrated that markers for angiogenesis can be useful in distinguishing between parathyroid hyperplasia and neoplasia, due to the increased angiogenesis in parathyroid proliferative lesions compared with parathyroid adenomas. These factors include, inter alia, VEGF, VEGFR2, CD105, and fibroblast growth factor-2. Although these differences appear promising in the differential diagnosis, there is an overlap between benign and malignant parathyroid lesions and there is no definite cutoff value. Loss of heterozygosity and comparative genomic hybridization studies revealed chromosomal regions frequently altered in parathyroid tumorigenesis at 9p21, 1p21-22, 1p35-36, and 11q13. Therefore, immunohistochemistry and genetic testing should be an additional diagnostic marker in combination with the traditional criteria. A better understanding of angiogenesis in primary hyperparathyroidism could result in more precise assessment of diagnosis and more effective treatment, especially in those cases, in which the commonly used parameters are insufficient.