Teresa Tellez

Overexpression of Clusterin in Human Breast Carcinoma

Clusterin has been implicated in numerous processes including active cell death, immune regulation, cell adhesion and morphological transformation. The purpose of this study was to examine clusterin expression in a large series of breast carcinomas by immunohistochemistry and in situ hybridization. The study included 40 samples of non-neoplastic glandular epithelia, 42 benign lesions, 15 atypical intraductal hyperplasias, 35 carcinomas in situ, 114 invasive carcinomas, and lymph node metastases from 40 patients. Epithelial normal cells were always negative for clusterin expression and only 19% of the benign lesions presented positive staining. In contrast to the benign lesions, however, the frequency of clusterin positive samples increased in atypical hyperplasias (47%, P = 0.08), intraductal carcinomas (49%, P = 0.01) and invasive carcinomas (53%, P < 0.001). Positive staining presented a cytoplasmic pattern, except in 3 cases of invasive carcinomas which had nuclear staining. Clusterin mRNA by in situ hybridization confirmed the specific cellular pattern of clusterin expression by immunohistochemistry. Clusterin expression was associated with large tumor size (P = 0.04), estrogen and progesterone receptor negative status (P = 0.02 and P = 0.001, respectively) and with the progression from primary carcinoma to metastatic carcinoma in lymph nodes (80% metastatic nodes had positive expression) (P = 0.004). Ten of 15 (67%) primary carcinomas without clusterin expression became positive in lymph node metastases, while most (22 of 25, 88%) of the clusterin-positive primary carcinomas were also immunoreactive in metastases. In survival analysis, clusterin expression did not represent a prognostic indicator by uni- or multivariate analysis. The increased clusterin expression in breast carcinomas tended to correlate inversely with the apoptotic index (P = 0.09) which indicates that clusterin gene expression is not a prerequisite to cellular death by apoptosis. From these results, we suggest that clusterin may have a role in tumorigenesis and progression of human breast carcinomas.

Anticlusterin treatment of breast cancer cells increases the sensitivities of chemotherapy and tamoxifen and counteracts the inhibitory action of dexamethasone on chemotherapy-induced cytotoxicity

IntroductionOverexpression of the apoptosis-related protein clusterin is associated with breast cancer development and tumor progression. We describe the use of clusterin-specific antisense oligonucleotides and antibodies to sensitize breast carcinoma cells to anticancer drugs routinely used in breast cancer therapy.MethodsMCF-7 and MDA-MB-231 cells were treated with the oligonucleotide or antibody, chemotherapeutic agents (doxorubicin or paclitaxel), tamoxifen, or with combinations of these.ResultsTreatments that include antisense clusterin oligonucleotide or antibody to clusterin have been shown to reduce the number of viable cells more effectively than treatment with the drugs alone. We also demonstrate that dexamethasone pretreatment of breast cancer cell lines inhibits chemotherapy-induced cytotoxicity and is associated with the transcriptional induction of clusterin. However, anticlusterin treatment increases chemotherapy-induced cytotoxicity, even in the presence of glucocorticoids, suggesting a possible role for these proteins in glucocorticoid-mediated survival.ConclusionThese data suggest that combined treatment with antibodies to clusterin or antisense clusterin oligodeoxynucleotides and paclitaxel, doxorubicin, or tamoxifen could be a novel and attractive strategy to inhibit the progression of breast carcinoma by regulation of the clusterin function. Moreover, glucocorticoid activation in breast cancer cells regulates survival signaling by the direct transactivation of genes like clusterin which encode proteins that decrease susceptibility to apoptosis. Given the widespread clinical administration of dexamethasone before chemotherapy, understanding glucocorticoid-induced survival mechanisms is essential for achieving optimal therapeutic responses.

Expression of the Antiapoptotic Proteins Clusterin and Bcl-2 in Laryngeal Squamous Cell Carcinomas

Bcl-2 and clusterin genes have been related to the inhibition of apoptosis, an event that plays a key role in malignant transformation and in invasive disease. In this work, we determine the significance of clusterin and bcl-2 expression in a large series of laryngeal carcinomas. We used immunohistochemical methods and in situ hybridization to examine the expression of these proteins. Nontumoral epithelial laryngeal tissues did not express clusterin and bcl-2 proteins. However, 9% (14 out of 154) and 25% of these tumors (39 of 154) had positive clusterin and bcl-2 staining, respectively. Clusterin expression was significantly related to the degree of local invasion and higher bcl-2 expression was found in these clusterin-positive tumors (p < 0.05). Bcl-2 expression was significantly correlated with supraglottic localization, nodal metastases, invasion in depth, and poorly differentiated tumors. However, by multivariate analysis, bcl-2 was shown to be an independent predictor of good prognosis in these tumors (OR = 0.12, 95% CI = 0.02–0.91). These findings indicate that clusterin and bcl-2 are upregulated in laryngeal carcinomas and their expression is related to the invasiveness of these tumors.

Clusterin expression is associated with decreased disease‐free survival of patients with colorectal carcinomas

Redondo M, Rodrigo I, Alcaide J, Tellez T, Roldan M J, Funez R, Diaz‐Martin A, Rueda A & Jiménez E
(2010) Histopathology 56, 932–936
Clusterin expression is associated with decreased disease‐free survival of patients with colorectal carcinomas

The Role of Clusterin (CLU) in Malignant Transformation and Drug Resistance in Breast Carcinomas

Breast cancer is the main cause of cancer-related death among women in Western countries. Current research is focused on identifying antiapoptotic proteins which could be a possible target for novel chemotherapeutic drugs. Secretory clusterin (sCLU) is an extracellular chaperone that has been functionally implicated in DNA repair, cell-cycle regulation, apoptotic cell death and tumorigenesis. The implication of sCLU in carcinogenesis and the progression of breast carcinomas make it an interesting gene, worthy of investigation. It has been reported to present powerful antiapoptotic activity and to perform a prosurvival function with most therapeutic treatments for breast cancer. This review summarizes our current understanding of the role of CLU in tumorigenesis, progression, and response to treatment in breast carcinomas.

Detection methods predict differences in biology and survival in breast cancer patients

BackgroundThe aim of this study was to measure the biological characteristics involved in tumorigenesis and the progression of breast cancer in symptomatic and screen-detected carcinomas to identify possible differences.MethodsFor this purpose, we evaluated clinical-pathological parameters and proliferative and apoptotic activities in a series of 130 symptomatic and 161 screen-detected tumors.ResultsAfter adjustment for the smaller size of the screen-detected carcinomas compared with symptomatic cancers, those detected in the screening program presented longer disease-free survival (RR = 0.43, CI = 0.19-0.96) and had high estrogen and progesterone receptor concentrations more often than did symptomatic cancers (OR = 3.38, CI = 1.72-6.63 and OR = 3.44, CI = 1.94-6.10, respectively). Furthermore, the expression of bcl-2, a marker of good prognosis in breast cancer, was higher and HER2/neu expression was lower in screen-detected cancers than in symptomatic cancers (OR = 1.77, CI = 1.01-3.23 and OR = 0.64, CI = 0.40-0.98, respectively). However, when comparing prevalent vs incident screen-detected carcinomas, prevalent tumors were larger (OR = 2.84, CI = 1.05-7.69), were less likely to be HER2/neu positive (OR = 0.22, CI = 0.08-0.61) and presented lower Ki67 expression (OR = 0.36, CI = 0.17-0.77). In addition, incident tumors presented a shorter survival time than did prevalent ones (RR = 4.88, CI = 1.12-21.19).ConclusionsIncident carcinomas include a variety of screen-detected carcinomas that exhibit differences in biology and prognosis relative to prevalent carcinomas. The detection method is important and should be taken into account when making therapy decisions.

Regulation of Clusterin Expression in Human Cancer via DNA Methylation

Background/Aims: Clusterin has attracted much recent attention because of its association with tumorigenesis and the progression of human carcinomas. The present study was designed to examine the role of clusterin methylation as an indicator of clusterin expression in tumor cell lines and breast tissue samples. Methods: For this purpose, we used methylation-sensitive restriction analysis followed by PCR. Results: None of the non-tumoral breast samples showed expression of clusterin by immunohistochemistry, and a methylated state was found in the promoter region of the gene. However, a demethylated state was found in 5 of 6 analyzed carcinoma cell lines. Four of 5 demethylated cell lines presented moderate to strong expression of clusterin, while no expression was detected in the unmethylated cell line. The inverse correlation found in most cell lines between clusterin expression and promoter methylation was also found in most human tumors analyzed (p < 0.001). Thus, a methylated state was present in 14 carcinomas, 12 of them with a null expression of clusterin, while a demethylated state was detected in 7 breast tumor samples, with 5 of them presenting strong expression. Conclusions: We conclude that clusterin expression is under epigenetic control via methylation of its promoter.

Downregulation of clusterin mediates sensitivity to protein kinase inhibitors in breast cancer cells.

The efficacy of protein kinase inhibitors (PKIs) has been shown in clinical assays for cancer, but as isolated agents, they only have a modest effect. One of the most important characteristics of mitogen-activated PKIs is their ability to decrease the apoptotic threshold of cancer cells, sensitizing them to the action of other antiapoptotic agents. The secretory clusterin protein is an inhibitor of apoptosis with a cytoprotective function. We describe the use of clusterin-specific antisense oligonucleotides and siRNA to sensitize breast carcinoma cells to several PKIs. MCF-7 and MDA-MB-231 cells were treated with antisense oligonucleotide or siRNA to clusterin and the following PKIs: H-89, chelerythrine and genistein. The three inhibitors used in this study upregulated clusterin expression and treatments that included antisense oligonucleotide or siRNA to clusterin reduced the number of viable cells more effectively than did treatment with the drugs alone. Therefore, treatment with such combinations may benefit patients with breast cancer.

Factors that influence treatment delay in patients with colorectal cancer

A prospective study was performed of patients diagnosed with colorectal cancer (CRC), distinguishing between colonic and rectal location, to determine the factors that may provoke a delay in the first treatment (DFT) provided. 2749 patients diagnosed with CRC were studied. The study population was recruited between June 2010 and December 2012. DFT is defined as time elapsed between diagnosis and first treatment exceeding 30 days. Excessive treatment delay was recorded in 65.5% of the cases, and was more prevalent among rectal cancer patients. Independent predictor variables of DFT in colon cancer patients were a low level of education, small tumour, ex-smoker, asymptomatic at diagnosis and following the application of screening. Among rectal cancer patients, the corresponding factors were primary school education and being asymptomatic. We conclude that treatment delay in CRC patients is affected not only by clinicopathological factors, but also by sociocultural ones. Greater attention should be paid by the healthcare provider to social groups with less formal education, in order to optimise treatment attention.

A sensitive enzyme immunoassay for angiotensin II in serum

A sensitive and specific enzyme immunoassay for measuring angiotensin II (AII) has been developed as a convenient alternative to a radioimmunoassay. An antiserum to AII was prepared using AII conjugated by carbodi-imide to rabbit serum albumin, and coated on to microwell plates. The labelled antigen was prepared from AII and horseradish peroxidase using the periodate method. This enzyme immunoassay was a simple two-step procedure: 0.1 ml of AII-extracted plasma was incubated for 1 h at 37 degrees C; and 1 ml of labeled AII was incubated for 1 h at 37 degrees C. Bound horseradish peroxidase activity was then determined using o-phenylenediamine as chromogen by measuring the absorbance at 492 nm. The lower detection limit of the assay was 3.5 pmol l-1. Between- and within-assay RSD values were 8.8-18.3% and 6.9-17%, respectively, for concentrations of 10-40 pmol l-1. The accuracy of the assay, determined by recovery and linearity experiments, was 89-106% for recovery and 91-126% for parallelism. The results obtained by the present ELISA method were well correlated with those obtained by an established radioimmunoassay (n = 10, r = 0.96, intercept = 0.9 and slope = 1.02). This assay is easy to perform, rapid and does not require radioisotopes; thus it could be widely applied in clinical laboratories.