It has been shown that the risk of breast cancer developing in certain morphologically identifiable benign breast lesions correlates with expression of estrogen receptor alpha (ER-alpha). Although ER-alpha and ER-beta genes share a large degree of homology, it is generally thought that their distribution and functions are substantially different in many tissues. Recent development of reliable antibodies to ER-beta has provided this first opportunity to test the hypothesis that the likelihood of malignant transformation in morphologically benign breast lesions can be accurately defined by the distribution and level of ER-beta expression relative to that of ER-alpha. Using a monoclonal antibody, ER-beta protein expression has been analyzed in 53 normal breasts and compared with a cohort of histologically distinct breast lesions of different prognostic risk (54 hyperplasia of usual type, 35 ductal carcinoma in situ, and 141 invasive cancers). All of these tissues were also assessed for ER-alpha. Expression of ER-beta protein was also analyzed in an additional spectrum of benign breast lesions with low or negligible risk of progression to malignancy. The median proportion of cells expressing ER-beta was highest in normal breast lobules (median 94.33%, interquartile range 78.25-99.00) but declined significantly through usual ductal hyperplasia (median 76.67, interquartile range 49.17-95.00, P = 0.002) and ductal carcinoma in situ (median 70.00, interquartile range 59.00-85.00, P = 0.009) to invasive cancer (median 60.00, interquartile range 50.00-80.00, P < 0.001). An appreciable proportion (33.81%) of ER-alpha-negative invasive cancers expressed ER-beta. A high but variable level of ER-beta expression occurred in the benign lesions. The data from the intact histologic tissues were evaluated with respect to the relative expression of ER-alpha and ER-beta in five mammary cell lines of different behavioral phenotype (MCF7, ZR-75, T47D, MDAMB231, HUMA121). The highly significant differences in expression and distinct tissue distributions of ER-alpha and ER-beta within the histologic lesions of defined risk, together with the data from the cell lines, support the original hypothesis that the tissue concentration, relative occurrence, and/or interaction of these two types of estrogen receptor may play an important role in modulating mammary tumorigenesis.

Prp2 is an RNA-dependent ATPase that activates the spliceosome before the first transesterification reaction of pre-mRNA splicing. Prp2 has extensive homology throughout the helicase domain characteristic of DEXD/ H-box helicases and a conserved carboxyl-terminal domain also found in the spliceosomal helicases Prp16, Prp22, and Prp43. Despite the extensive homology shared by these helicases, each has a distinct, sequential role in splicing; thus, uncovering the determinants of specificity becomes crucial to the understanding of Prp2 and the other DEAH-splicing helicases. Mutations in an 11-mer near the C-terminal end of Prp2 eliminate its spliceosome binding and splicing activity. Here we show that a helicase-associated protein interacts with this domain and that this interaction contributes to the splicing process. First, a genome-wide yeast two-hybrid screen using Prp2 as bait identified Spp2, which contained a motif with glycine residues found in a number of RNA binding proteins. SPP2 was originally isolated as a genetic suppressor of a prp2 mutant. In a reciprocal screen, Spp2 specifically pulled out the C-terminal half of Prp2. Mutations in the Prp2 C-terminal 11-mer that disrupted function or spliceosome binding also disrupted Spp2 interaction. A screen of randomly mutagenized SPP2 clones identified an Spp2 protein with a mutation in the G patch that could restore interaction with Prp2 and enhanced splicing in a prp2 mutant strain. The study identifies a potential mechanism for Prp2 specificity mediated through a unique interaction with Spp2 and elucidates a role for a helicase-associated protein in the binding of a DEXD/H-box protein to the spliceosome.Pre-mRNA splicing is a dynamic process through which snRNPs and trans-acting proteins interact in an ordered manner in the spliceosome to remove introns from pre-mRNA. The process of splicing can be broken down in vitro to the steps of spliceosome formation, the first transesterification reaction, the second transesterification reaction, the release of mature mRNA, and the recycling of the snRNPs. DEXD/H-box helicases act upon the spliceosome to catalyze assembly, activation, and disassembly of the spliceosome in an ordered, stepwise manner (40). Comprehending the action of these helicases and their effect on the spliceosome is essential to understanding the process of pre-mRNA splicing.Prp2 is an RNA-dependent ATPase (21) belonging to the DEAH subfamily of DEXD/H-box helicases that includes Prp16, Prp22, and Prp43 (40). The DEAH splicing factors share homology extending from the helicase domain through the carboxyl terminus. Despite the extensive homology shared between the DEAH family splicing helicases, each has a distinct, sequential role in the splicing reaction. Prp2 activates the spliceosome upon ATP hydrolysis before the first transesterification reaction (20, 22), Prp16 acts before the second transesterification reaction (38), Prp22 has roles in the second step of pre-mRNA splicing and mRNA release from the spliceosome (37, 42), and Prp43 is involv...

We demonstrate that, in human bladder cancer, amplification of the E2F3 gene, located at 6p22, is associated with overexpression of its encoded mRNA transcripts and high levels of expression of E2F3 protein. Immunohistochemical analyses of E2F3 protein levels have established that around one-third (33/101) of primary transitional cell carcinomas of the bladder overexpress nuclear E2F3 protein, with the proportion of tumours containing overexpressed nuclear E2F3 increasing with tumour stage and grade. When considered together with the established role of E2F3 in cell cycle progression, these results suggest that the E2F3 gene represents a candidate bladder cancer oncogene that is activated by DNA amplification and overexpression.

No abstract

TIG1 may be a tumor suppressor gene whose diminished expression is involved in the malignant progression of prostate cancer.

To test the hypothesis that expression of osteopontin (OPN), an integrin-binding glycoprotein, can independently predict the potential aggressiveness of prostate cancer, the status of OPN expression in benign and malignant prostate cancer cell lines and tissues was analysed by Western blot and immunohistochemistry. Amongst the four prostate cell lines analysed, the level of OPN expressed in the benign PNT-2 cells was set at 1, the relative level of OPN expressed in the weakly malignant cell line LNCaP was increased to 1.5. In the highly malignant cell lines Du-145 and PC-3, the level of OPN expression was further increased to 2.9 and 4.4, respectively. An increased expression of OPN was also observed in the prostate tissue samples. When the level of OPN in normal tissue was set at 1, its level in benign prostate hyperplasia (BPH) was similar at 0.99 6 0.2, whereas the OPN level in the highly malignant carcinoma tissue was greatly increased by nearly 6-fold to 5.9 6 0.3. Amongst the 116 cases examined immunocytochemically, of the 10 normal cases, 3 (30%) were unstained and 7 (70%) stained weakly positive (1). Amongst the 36 BPH samples, 32 (89%) stained weakly positive (1) and 4 (11%) were unstained (2). For the 70 carcinomas analysed, 31 (44%) stained strongly positive (111), 20 (29%) stained moderately positive (11) and 19 (27%) stained weakly positive (1). These results showed that the level of OPN expressed between the normal and the BPH samples was not significantly different (Fisher's exact test, p 5 0.16). However, in comparison to that in the BPH samples, the expression of OPN in the carcinoma tissues was significantly increased (Chi-square test, p < 0.0001). Kaplan-Meier survival analysis showed that the increased level of OPN expression was significantly (n 5 70, p 5 0.03) associated with reduced survival time of the patients. The OPN expression was increased with the increasing Gleason scores of the carcinomas (Chi-square test, p < 0.001). The results in our study support our hypothesis and suggest that the increased OPN level may be involved in the malignant transformation of prostate epithelial cells and OPN expression level is an important determinant for patient survival. ' 2005 Wiley-Liss, Inc.Key words: prostate carcinoma; osteopontin; benign prostate hyperplasia (BPH); Gleason scores; patient survival Prostate cancer has become the most common male cancer and the second leading cause of death from male malignant disease in the United States and Europe, and this disease kills more than 40,000 men per year in the developed world. 1,2 Despite the increasing incidence, the molecular basis of prostate cancer progression, invasion and metastasis is still not fully understood. The complicated molecular pathology of prostate cancer may involve a series of sequential genetic events, which cause the initiation and progression of the malignant changes of prostate epithelial cells. The complicated genetic events responsible for tumorigenicity and metastasis of prostate cancer may be classified in a simple ...

Expression of Na + channel protein was analysed in established cell lines of rat and human prostatic carcinoma origin by flow cytometry using a fluorescein-labelled polyclonal antibody. In many cell lines examined, the obtained frequency distribution profiles were bimodal and identified a subpopulation of cells which expressed high levels of Na + channel protein. A significant positive correlation was demonstrated between the proportion of channel-expressing cells and the functional ability of individual cell lines to invade a basement membrane matrix in vitro. In addition, two transfectant cell lines containing rat prostate cancer genomic DNA were found to express significantly elevated levels of Na + channel protein when compared with the original benign recipient cell line. Enhanced Na + channel expression by two metastatic derivatives of these transfectant cells directly correlated with increased invasiveness in vitro. These studies strongly support the hypothesis that expression of Na + channel protein and the metastatic behaviour of prostatic carcinoma cells are functionally related, either by endowing the membranes of these cells with specialised electrophysiological properties (e.g. enhancing their motility and/or secretory activities) and/or by perturbing endogenous mechanisms regulating ionic homeostasis within the cells.z 1998 Federation of European Biochemical Societies.

No abstract