Aleksandra Piotrowska

Podoplanin expression by cancer-associated fibroblasts predicts poor outcome in invasive ductal breast carcinoma

Pula B, Jethon A, Piotrowska A, Gomulkiewicz A, Owczarek T, Calik J, Wojnar A, Witkiewicz W, Rys J, Ugorski M, Dziegiel P & Podhorska‐Okolow M 
(2011) Histopathology 59, 1249–1260 
Podoplanin expression by cancer‐associated fibroblasts predicts poor outcome in invasive ductal breast carcinoma

Long term potentiation affects intracellular metalloproteinases activity in the mossy fiber — CA3 pathway

Matrix Metalloproteinases (MMPs) are a family of endopeptidases known to process extracellular proteins. In the last decade, studies carried out mainly on the Schaffer collateral-CA1 hippocampal projection have provided solid evidence that MMPs regulate synaptic plasticity and learning. Recently, our group has shown that MMP blockade disrupts LTP maintenance also in the mossy fiber-CA3 (mf-CA3) projection (Wojtowicz and Mozrzymas, 2010), where LTP mechanisms are profoundly different (NMDAR-independent and presynaptic expression site). However, how plasticity of this pathway correlates with activity and expression of MMPs remains unknown. Interestingly, several potential MMP substrates (especially of gelatinases) are localized intracellularly but little is known about MMP activity in this compartment. In the present study we have asked whether LTP is associated with the expression and activity of gelatinases in apparent intra- and extracellular compartments along mf-CA3 projection. In situ zymography showed that LTP induction was associated with increased gelatinases activity in the cytoplasm of the hilar and CA3 neurons. Using gelatin zymography, immunohistochemistry and immunofluorescent staining we found that this effect was due to de novo synthesis and activation of MMP-9 which, 2-3h after LTP induction was particularly evident in the cytoplasm. In contrast, MMP-2 was localized preferentially in the nuclei and was not affected by LTP induction. In conclusion, we demonstrate that LTP induction in the mf-CA3 pathway correlates with increased expression and activity of MMP-9 and provide the first evidence that this increase is particularly evident in the neuronal cytoplasm and nucleus.

alpha-Amanitin induced apoptosis in primary cultured dog hepatocytes.

Amatoxin poisoning is caused by mushroom species belonging to the genera Amanita, Galerina and Lepiota with the majority of lethal mushroom exposures attributable to Amanita phalloides. High mortality rate in intoxications with these mushrooms is principally a result of the acute liver failure following significant hepatocyte damage due to hepatocellular uptake of amatoxins. A wide variety of amatoxins have been isolated; however, alpha-amanitin (alpha-AMA) appears to be the primary toxin. Studies in vitro and in vivo suggest that alpha-AMA does not only cause hepatocyte necrosis, but also may lead to apoptotic cell death. The objective of this study was to evaluate the complex hepatocyte apoptosis in alpha-AMA cytotoxicity. All experiments were performed on primary cultured canine hepatocytes. The cells were incubated for 12 h with alpha-AMA at a final concentration of 1, 5, 10 and 20 microM. Viability test (MTT assay), apoptosis evaluation (TUNEL reaction, detection of DNA laddering and electron microscopy) were performed at 6 and 12 h of exposure to alpha-AMA. There was a clear correlation between hepatocyte viability, concentration of alpha-AMA and time of exposure to this toxin. The decline in cultured dog hepatocyte viability during the exposure to alpha-AMA is most likely preceded by enhanced cellular apoptosis. Our results demonstrate that apoptosis might contribute to pathogenesis of the severe liver injury in the course of amanitin intoxication, particularly during the early phase of poisoning.

Benzylpenicillin, acetylcysteine and silibinin as antidotes in human hepatocytes intoxicated with α-amanitin

Fatalities due to mushroom poisonings are increasing worldwide, with high mortality rate resulting from ingestion of amanitin-producing species. Intoxications caused by amanitin-containing mushrooms represent an unresolved problem in clinical toxicology since no specific and fully efficient antidote is available. The objective of this study was a comparative evaluation of benzylpenicillin (BPCN), acetylcysteine (ACC) and silibinin (SIL) as an antidotes in human hepatocytes intoxicated with alpha-amanitin (alpha-AMA). All experiments were performed on cultured human hepatocytes. Cytotoxicity evaluation of cultured cells using MTT assay and measurement of lactate dehydrogenase (LDH) activity was performed at 12, 24 and 48h of exposure to alpha-AMA and/or antidotes. The significant decline of cell viability and significant increase of LDH activity were observed in all experimental hepatocyte cultures after 12, 24 and 36h exposure to alpha-AMA at concentration 2microM. Exposure of the cells to alpha-AMA resulted also in significant reduction of cell spreading and attachment. However, addition of tested antidotes to experimental cultures significantly stimulated cell proliferation and attachment. In cell cultures exposed simultaneously to alpha-AMA and tested antidotes cytotoxic parameters (MTT and LDH) were not significantly different from control incidences. The cytoprotective effect of all antidotes was not dose-related, which reflects a high efficacy of all these substances. Administration of studied antidotes was not associated with any adverse effects in hepatocytes. The administration of ACC, BPCN or SIL to human hepatocyte cultures showed a similar strong protective effect against cell damage in alpha-AMA toxicity.

Early morphological and functional alterations in canine hepatocytes due to α-amanitin, a major toxin of Amanita phalloides.

The toadstool death cap (Amanita phalloides) and its subspecies, destroying angel (A. virosa) and death angel (A. verna) are responsible for nearly 95% of all fatal mushroom poisonings. High mortality rate in A. phalloides intoxications is principally a result of the acute liver failure following significant hepatocyte damage due to hepatocellular uptake of amanitins, the major toxins of this mushroom. This study evaluated early morphological and functional alterations in hepatocytes exposed to different concentrations of α-amanitin (α-AMA). All experiments were performed on cultured canine hepatocytes since intoxicated with A. phalloides dogs have clinical course and pathological findings similar to those seen in humans. The overall functional integrity and viability of cultured hepatocytes were assessed using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and by measurements of lactate dehydrogenase (LDH), total protein, and urea levels. Our results showed that the course of α-AMA toxicity in cultured dog hepatocytes is divided into two phases. The first phase comprises functional cell impairments expressed by significant increase of LDH activity and inhibition of protein and urea synthesis when compared with the control group. This is followed by discrete changes in hepatocyte ultrastructure, including marginalization and condensation of nuclear chromatin, as well as formation of the foamlike cytoplasm. The second stage is lethal and is characterized by ongoing necrosis, and/or apoptosis. This may be related to dose of toxin and time of exposure.

Influence of commonly used clinical antidotes on antioxidant systems in human hepatocyte culture intoxicated with α-amanitin

α-Amanitin (α-AMA) is the main toxin of Amanita phalloides and its subspecies (A. virosa and A. verna). The primary mechanism of α-AMA toxicity is associated with protein synthesis blocking in hepatocytes. Additionally, α-AMA exhibits prooxidant properties that may contribute to its severe hepatotoxicity. The aim of the present study was to assess the effect of α-AMA on lipid peroxidation and the activities of superoxide dismutase (SOD) and catalase (CAT) in human hepatocyte culture. The effects of benzylpenicillin (BPCN), N-acetyl-L-cysteine (ACC), and silibinin (SIL) on SOD and CAT activities and on lipid peroxidation in human hepatocyte culture intoxicated with α-AMA were also examined. In human hepatocyte culture, 48-hour exposure to α-AMA at a 2-μM concentration caused an increase in SOD activity, a reduction of CAT activity, and a significant increase in lipid peroxidation. Changes in SOD and CAT activity caused by α-AMA could probably enhance lipid peroxidation by increased generation of hydrogen peroxide combined with reduced detoxification of that oxygen radical. The addition of antidotes (ACC or SIL) to the culture medium provided more effective protection against lipid peroxidation in human hepatocytes intoxicated with α-AMA than the addition of BPCN, possessing no antioxidant properties.

Benzylpenicyllin and acetylcysteine protection from α-amanitin-induced apoptosis in human hepatocyte cultures

High mortality rate in Amanita phalloides (death cap) intoxications is a result of the acute liver failure following hepatocyte damage due to hepatocellular uptake of amatoxins. α-Amanitin (α-AMA), the major amatoxin, blocks a RNA polymerase II, which results in inhibition of transcription of DNA and protein synthesis processes and leads to hepatocyte death. α-AMA is also a strong apoptosis inductor and may play a significant role in pathogenesis of hepatic damage in course of amanitin intoxication. The aim of this study was to examine mechanisms of α-AMA-induced apoptosis in human hepatocytes, as well as in determining if commonly clinically used antidotes benzylpenicillin (BPCN) and N-acetylcysteine (ACC) are able to protect human hepatocytes against α-AMA-induced apoptosis. The experiment was performed on cultured human hepatocytes. Viability of cultured hepatocytes was assessed using the MTT assay, whereas apoptosis processes were evaluated by the electron microscopy, detection of DNA laddering, determination of caspase-3 activity, and measuring annexin V, p53 and Bcl-2 protein concentration. Cytotoxicity and apoptosis evaluation were performed after 24 h of exposure to α-AMA and/or tested antidotes.Both ACC and BPCN were well tolerated by human hepatocyte cultures, and exposure to those substances did not reduce cell viability nor induce apoptosis. Exposure of hepatocytes to α-AMA at concentration 2μM resulted in derangement of cell cultures, apoptosis and significant reduction in cell viability. α-AMA-induced apoptosis in human heptocyte cultures is p53- and caspase-3-dependent. Human hepatocyte cultures are exposed simultaneously to α-AMA and tested antidotes (BPCN or ACC) showed significantly higher cell viability and significantly lower values of apoptosis markers compared to the cultures exposed to α-AMA only.

Angiotensin II type 1 receptor (AT-1R) expression correlates with VEGF-A and VEGF-D expression in invasive ductal breast cancer.

Recent studies point to the involvement of angiotensin II (Ang II) receptor type 1 (AT-1R) on processes of metastasing, stimulation of invasiveness and angiogenesis in tumours. In this study, the correlation between intensity of AT-1R expression and expression of lymph- and angiogenesis markers in invasive ductal breast cancers (IDC) was examined. Immunohistochemical studies (IHC) were performed on archival material of 102 IDC cases. Only 28 (27.5%) cases manifested low AT-1R expression while 74 (72.5%) cases demonstrated a moderate or pronounced AT-1R expression. Expression intensity of AT-1R was found to correlate with expressions of VEGF-A (r = 0.26; p = 0.008) and VEGF-D (r = 0.24; p = 0.015). Out of the examined markers of angiogenesis and lymphangiogenesis only the pronounced expression of VEGF-C was found to correlate with patient poor clinical outcome (p = 0.009). The positive correlation between AT-1R and VEGF-A and VEGF-D could point to stimulatory action of Ang II on their expression what might result in augmented lymph- and angiogenesis in IDC.

Hsp-27 Expression in Invasive Ductal Breast Carcinoma

The aim of this study was to determine the intensity of Hsp-27 protein expression in fibrocystic breast changes (FC) and invasive ductal breast carcinoma (IDC) and to examine its impact on patients’ clinico-pathological characteristics and overall survival. Immunohistochemical reactions were conducted on archival samples of 20 cases of FC and 101 cases of IDC treated in the years 1999-2002. Nuclear-cytoplasmic Hsp-27 expression was observed in 92 (92.1%) of the examined cases of IDC and all the cases of FC. Significantly higher Hsp-27 expression was observed in G2 (p<0.01) and G3 cases (p<0.0001) as compared to FC. HER-2 positive cases had higher Hsp-27 expression (p=0.0153), than HER-2 negative cases. Our research showed that Hsp-27 could have a impact on tumour malignancy. Moreover, the positive correlation between expression of Hsp-27 and HER-2 positive cases was demonstrated.

Expression of metallothionein I/II and Ki-67 antigen in various histological types of basal cell carcinoma

Basal cell carcinoma (BCC) is the most frequent skin cancer, with many different histological subtypes. Recent studies have investigated the expression of proliferative markers, but little is known about the expression of metallothioneins (MT) in different histological subtypes of this cancer and their impact on proliferation intensity in BCC. In this study, we examined MT-I/II expression by immunohistochemistry in 58 different histological subtypes of BCC (38 nodular, six adenoid, eight infiltrative, and six metatypic cases) and correlated its expression with tumor size and Ki-67 proliferation rate. Statistical analysis revealed no significant differences in the expression of studied markers in regard to the histological subtype. A positive correlation between MT and Ki-67 expression was observed for all the studied cases (r = 0.26; p = 0.049), but was even stronger in the metatypic subtype of BCC (r = 0.85; p = 0.033). MT and Ki-67 expression did not correlate with tumor size. In conclusion, it seems that metallothioneins may have an impact on the proliferation rate of BCC, but further studies are required to determine whether MT may be a risk factor of recurrences.