Expression of leptin and its receptor in female breast cancer in relation with selected apoptotic markers.

Leptin and its receptor may be engaged in pathogenesis of breast cancer among various human tumors. In vitro investigations showed leptin-mediated escalation of estrogen synthesis and boosted activity of estrogen receptor ERalpha. Furthermore, leptin induced growth of malignant cells, counteracted apoptosis and stimulated cell migration as well as overexpression of angiogenic factors and degrading enzymes that split network of intercellular matrix. On the other side, leptin has been reported to favor apoptosis, lately. Proapoptotic effect of leptin action was revealed in interstitial cells of bone marrow and adipocytes. Our past reports provide evidences for overexpression of leptin and its receptor in breast cancer in comparison with benign mammary lesions. In current study we aimed at assessment of eventual relationships between leptin, leptin receptor and selected protein regulators of apoptosis in breast cancer. We applied immunohistochemistry for leptin, leptin receptor, anti-apoptotic Bcl-2 and Bcl-xL as well as pro-apoptotic Bak and Bax expression assessment in 106 cases of human breast cancers. The immunoreaction was graded and statistically evaluated. Expression of leptin was positively correlated with Bcl-xL, Bak and Bax (

Increased expression of gap junction protein--connexin 32 in lymph node metastases of human ductal breast cancer.

Gap junctions are specialized cell membrane channels composed of connexins (Cxs), which mediate the direct passage of small molecules between adjacent cells. They are involved in the regulation of cell cycle, cell signaling and differentiation as well as probably invasion and metastasis. Up to now, Cx32 status in human breast cancer has not been studied. Consequently, the aim of the present study was the evaluation of the expression of connexin 32 (Cx32) in primary breast tumors (PTs) and matched-paired metastases to lymph nodes (MLNs) in correlation with selected clinicopathological features. Tissue samples from 79 women were examined by immunohistochemistry, using the streptavidin-biotin-peroxidase complex technique for Cx32. Cytoplasmic expression of Cx32 was detected in 31 of 79 breast cancers (39.2%). Both epithelial and myoepithelial cells of normal ducts adjacent to the tumor did not express Cx32. Increased expression of studied Cx was observed in metastases to lymph nodes relative to primary tumors. Additionally, Cx32-negative primary tumors developed Cx32-positive metastases. Statistical comparisons of Cx32 expression in the matched pairs indicate that this protein significantly increased in lymph node metastases compared to primary tumors (

Expression of connexins 26, 32 and 43 in the human colon--an immunohistochemical study.

Gap junctional intercellular communication (GJIC) is a mechanism for direct cell-to-cell signalling and is mediated by gap junctions (GJs), which consist of proteins called connexins (Cxs). GJIC plays a critical role in tissue development and differentiation and is important in maintenance of tissue homeostasis. The purpose of the study was to evaluate the expression of Cx26, Cx32 and Cx43 in the human colon. Surgical specimens were obtained from patients who underwent surgical resection of colorectal tumours. Tissue samples (50 cases) were collected from normal colon, at the maximum distance from the tumor. Using antibodies for Cx26, Cx32 and Cx43, immunohistochemical detection was made. In epithelial cells, strong Cx26 immunoreactivity was found, whereas Cx32 and Cx43 were sparsely distributed. Strong Cx43 immunostaining in muscularis mucosae was observed. In the circular layer of muscularis externa, expression of Cx43 and Cx26 was seen, but only in the portion closest to the submucosa. No immunoreactivity was found in the longitudinal muscle layer. Small vessels stained positively only for Cx43. Furthermore, there was no difference in staining between samples derived from various sections of the colon. This study showed immunohistochemically for the first time the expression of Cx26 in human colon mucosa

STAT3 and hypoxia induced proteins--HIF-1alpha, EPO and EPOR in relation with Bax and Bcl-xL in nodal metastases of ductal breast cancers.

STAT3 contributes to increase of EPO expression which is also HIF-1 dependent. EPO receptor activates STAT3. Expressions of STAT3 and hypoxia induced proteins: HIF-1, EPO and EPOR show mutual correlations in primary ductal breast cancers, which suggest co-operation among these proteins. Moreover, EPO-EPOR signaling was reported to mediate cell survival by targeting Bcl-xL in competition with Bax-dependent apoptosis. Our present study was focused on immunohistochemical evaluation of STAT3, HIF-1alpha, EPO and EPOR in relation to apoptosis regulators, Bax and Bcl-xL in 39 metastases of ductal breast cancers to lymph nodes. The proteins were abundantly expressed by cancer cells. HIF-1alpha correlated with EPOR in all and in chemotherapy treated metastases (r=0.428, p=0.007 and r=0.462, p=0.040, respectively). HIF-1 associated significantly with EPO in chemotherapy spared metastases (r=0.549, p=0.015) and comparison between those proteins almost reached statistical significance in entire number of metastatic breast cancers (r=0.309, p=0.056). Metastases from T2 primary tumors had significantly higher expressions of HIF-1alpha, EPO and EPOR compared to T1 originating metastases (p=0.020, p=0.028, p=0.021, respectively). Bax correlated with EPO and EPOR in all studied nodal metastases (r=0.449, p=0.006 and r=0.421, p=0.011, respectively) and so did Bcl-xL with HIF-1alpha (r=0.440, p=0.007), EPO and EPOR (r=0.383, p=0.021, r=0.495, p=0.002, respectively). Metastatic breast cancers seem to be areas of intensive signaling by STAT3, HIF-1, EPO and EPOR. Strong Bax and Bcl-xL labeling reflects accelerated cell turnover in nodal metastases. By means of association with Bcl-xL, HIF-1alpha, EPO and EPOR could favor growth of nodal metastases and survival of breast cancers cells

Expression of connexin 26 in endometrial adenocarcinoma--analysis of correlations with some anatomoclinical features.

Alterations of gap junctional intercellular communication appear to play a role in the development and progression of cancer. Gap junction channel is composed of two connexons - hexameric units formed of transmembrane proteins called connexins (Cxs). The aim of the study was to evaluate the expression and localization of Cx26 in 73 cases of endometrial cancers and to estimate the relationships between expression of this protein and selected anatomoclinical features. The control group consisted of 20 sections of normal endometrium in various menstrual cycle phases, obtained from premenopausal women. In the normal endometrium punctate, membrane-associated immunoreactivity for Cx26 was observed. 54 of 73 endometrial cancers showed Cx26 expression, but 46/54 (85%) immunopositive sections revealed cytoplasmic localization for Cx26 with granular or occasionally diffuse immunostaining pattern. In addition, part of Cx26-positive tumours showed mixed: cytoplasmic and membranous staining pattern and focally also nuclear or perinuclear immunostaining was present. In 21/54 (39%) of Cx26-positive cases weak staining pattern was seen, however in 33/54 (61%) cancers strong reaction was noted. We did not find relationship between Cx26 expression and patients' age, histological type of cancer and histological grade, nevertheless we observed positive association between Cx26 expression and tumour size (p=0.037). In conclusion, our results suggest that transformed malignant cells continue to produce Cx26, which are probably not assembled into functional gap junction channels, but could still play other roles in endometrial cancer cells

Increased Expression of Leptin and the Leptin Receptor as a Marker of Breast Cancer Progression: Possible Role of Obesity-Related Stimuli

Abstract Purpose: Recent in vitro studies suggested that the autocrine leptin loop might contribute to breast cancer development by enhancing cell growth and survival. To evaluate whether the leptin system could become a target in breast cancer therapy, we examined the expression of leptin and its receptor (ObR) in primary and metastatic breast cancer and noncancer mammary epithelium. We also studied whether the expression of leptin/ObR in breast cancer can be induced by obesity-related stimuli, such as elevated levels of insulin, insulin-like growth factor-I (IGF-I), estradiol, or hypoxic conditions. Experimental Design: The expression of leptin and ObR was examined by immunohistochemistry in 148 primary breast cancers and 66 breast cancer metastases as well as in 90 benign mammary lesions. The effects of insulin, IGF-I, estradiol, and hypoxia on leptin and ObR mRNA expression were assessed by reverse transcription-PCR in MCF-7 and MDA-MB-231 breast cancer cell lines. Results: Leptin and ObR were significantly overexpressed in primary and metastatic breast cancer relative to noncancer tissues. In primary tumors, leptin positively correlated with ObR, and both biomarkers were most abundant in G3 tumors. The expression of leptin mRNA was enhanced by insulin and hypoxia in MCF-7 and MDA-MB-231 cells, whereas IGF-I and estradiol stimulated leptin mRNA only in MCF-7 cells. ObR mRNA was induced by insulin, IGF-I, and estradiol in MCF-7 cells and by insulin and hypoxia in MDA-MB-231 cells. Conclusions: Leptin and ObR are overexpressed in breast cancer, possibly due to hypoxia and/or overexposure of cells to insulin, IGF-I, and/or estradiol

The relationships between hypoxia-dependent markers: HIF-1alpha, EPO and EPOR in colorectal cancer

Abstract: Hypoxia triggers production of several cytoprotective proteins. Hypoxia-inducible factor 1alpha (HIF-1α) is a powerful stimulator of transcription of many genes, including erythropoietin (EPO) in hypoxia-affected cells. Recent data have also implicated signaling by EPO receptor (EPOR) as a new factor influencing tumor progression. The aim of the study was to detect by immunohistochemistry the presence of HIF-1α, EPO and EPOR in colorectal cancer (CRC) in reference to clinicopathological variables. We found the presence of the studied proteins in specimens of all 125 CRC patients which is suggestive of the occurrence of hypoxia in colorectal cancer tissues. The expression of HIF-1α correlated significantly with the presence of EPO and EPOR in all samples (P < 0.001, r = 0.549 and P < 0.001, r = 0.536, respectively). Significant correlations (from P < 0.024 to P < 0.001) were found in the analyses of CRC subgroups such as histopathological type tumor, tumor grade, tumor stage and patients with lymph nodes metastases. The same high significant correlations (P < 0.001) were observed in group of sex, age and tumor location. However, the values of the correlation coefficients (r) which usually ranged from 0.5 to 0.6 suggest the existence of independent or concurrent mechanism stimulating generation of these proteins in colorectal cancer

Relationships between hypoxia markers and the leptin system, estrogen receptors in human primary and metastatic breast cancer: effects of preoperative chemotherapy

<p>Abstract</p> <p>Background</p> <p>Tumor hypoxia is marked by enhanced expression of hypoxia-inducible factor-α (HIF-1α) and glucose transporter-1 (Glut-1). Hypoxic conditions have also been associated with overexpression of angiogenic factors, such as leptin. The aim of our study was to analyze the relationships between hypoxia markers HIF-1α, Glut-1, leptin, leptin receptor (ObR) and other breast cancer biomarkers in primary and metastatic breast cancer in patients treated or untreated with preoperative chemotherapy.</p> <p>Methods</p> <p>The expression of different biomarkers was examined by immunohistochemistry in 116 primary breast cancers and 65 lymph node metastases. Forty five of these samples were obtained form patients who received preoperative chemotherapy and 71 from untreated patients.</p> <p>Results</p> <p>In primary tumors without preoperative chemotherapy, HIF-1α and Glut-1 were positively correlated (p = 0.02, r = 0.437). HIF-1α in primary and metastatic tumors without preoperative therapy positively correlated with leptin (p < 0.0001, r = 0.532; p = 0.013, r = 0.533, respectively) and ObR (p = 0.002, r = 0.319; p = 0.083, r = 0.387, respectively). Hypoxia markers HIF-1α and Glut-1 were negatively associated with estrogen receptor alpha (ERα) and positively correlated with estrogen receptor beta (ERβ). In this group of tumors, a positive correlation between Glut-1 and proliferation marker Ki-67 (p = 0.017, r = 0.433) was noted. The associations between HIF-1α and Glut-1, HIF-1α and leptin, HIF-1α and ERα as well as Glut-1 and ERβ were lost following preoperative chemotherapy.</p> <p>Conclusions</p> <p>Intratumoral hypoxia in breast cancer is marked by coordinated expression of such markers as HIF-1α, Glut-1, leptin and ObR. The relationships among these proteins can be altered by preoperative chemotherapy.</p