Progesterone Receptor (PR) Promoter Methylation – Role as a Predictive and Prognostic Marker in Breast Cancer

Estrogen receptor α expression is a well known and clinically utilized predictor of endocrine treatment response. In addition, loss of expression of the progesterone receptor (PR), an estrogen induced gene, has been shown to be associated with resistance to endocrine therapy. PR is known to be epigenetically regulated by DNA methylation, but only a few studies have correlated PR DNA methylation with its expression in breast cancer. Previous studies are contradictory and have been limited by small sample size. There is also evidence that differential expression of the two PR isoforms, PRA and PRB, might contribute to breast tumorigenesis, and altered hormone response. Whether PRA and/or PRB DNA methylation could predict response to endocrine therapy remains an open question. Further, there are no published studies so far testing whether PRA and/or PRB methylation have prognostic significance.Our objective was 1) to determine whether there was an association between PRA and/or PRB methylation levels with total PR expression in breast tumors, and 2) to determine if PRA and/or PRB methylation would have predictive and/or prognostic value. For this study, we utilized tumor DNA from patients with ER-positive breast tumors which were treated with adjuvant tamoxifen after surgery (n=500), and from patients treated with surgery only (n=500). PR expression was determined by ligand binding assay, and PRA and PRB promoter methylation was measured by bisulfite pyrosequencing.Both PRA and PRB methylation were significantly (p<0.0001) associated with PR expression, in an inverse relationship. Low PR expression was significantly (p=0.02) associated with worse overall survival (OS), and there was a trend towards shorter disease free survival (DFS) in the tamoxifen treated group. There was no association between PR expression and survival in the untreated group. PRA methylation was significantly (p<0.0001) associated with PRB methylation. Intriguingly, increased PRA methylation was significantly associated with shorter DFS (p=0.047) and OS (p=0.0067) in tamoxifen treated patients, and with shorter OS (p=0.008) in the untreated patients. In contrast, there was no significant association between PRB methylation and survival in either tamoxifen treated or untreated patients.Our results show that PR expression is significantly associated with PR methylation. The data suggest that PRA methylation is a predictive marker for tamoxifen response and also a prognostic marker for breast cancer progression. This is the largest study so far to elucidate the association of PRA and PRB methylation with PR status, response to tamoxifen, and tumor prognosis, and we believe that it provides useful insights into the role of PR methylation in breast tumorigenesis.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2002.

Heterogeneity of gene expression in stromal fibroblasts of breast carcinomas and normal breast

Abstract #105

Background: The cancer microenvironment plays a critical role in tumor development and progression. Cancer associated fibroblasts (CAF) constitute a significant component of the tumor stroma and participate in reciprocal communication with the tumor cells. Information on differential gene expression specifically in stromal fibroblasts is sparse and data describing the variability of gene expression in CAF and normal fibroblasts (NF) is currently lacking. The purpose of this study was to identify genes differentially expressed in CAF and matched NF and to analyze the heterogeneity of gene expression profiles in the two cell types.
 Materials and methods: Fibroblast cell cultures were established from 6 patients with primary invasive breast cancer. Gene expression profiles were generated using oligonucleotide microarrays (Affymetrix HG-U133 Plus 2.0). Differentially expressed genes were ranked using Empirical Bayes modeling. A cut-off value of 0.005 was chosen for the posterior probability of equivalent expression. Lists of overexpressed genes were generated after eliminating genes with less than two-fold overexpression.
 Results: 17 genes were overexpressed in CAF compared to NF with known functions in paracrine and intracellular signaling, transcription regulation and extracellular matrix production. Using the same posterior probability cut-off, we identified 7 genes which were expressed at least two-fold higher in NF than in CAF. These genes have purported roles in steroid hormone metabolism, transcription, migration and cell signaling. Using semiquantitative RT-PCR and immunohistochemistry, we confirmed the over- and underexpression of a subset of 10 differentially expressed genes. The heterogeneity of gene expression in CAF vs. NF was compared with F-tests to determine variances. The estimated probability of NF gene expression variance being higher than CAF gene expression variance was 0.547 with a 95% confidence interval of 0.543 to 0.551 (p<0.0001), indicating that gene expression is more variable in NF than in CAF. By ranking the q-values of individual genes we identified 3 known genes, which show a significant difference in variance between CAF and NF (p<0.05).
 Conclusion: Altered gene expression in fibroblasts likely contributes to tumor growth and progression by enhancing ECM production, promoting stromal-epithelial paracrine signaling and altering steroid hormone metabolism. The inter-individual heterogeneity of gene expression in NF may indicate that the mammary stroma varies between individuals, supporting the hypothesis that the ability of the stroma to act as a barrier to cancer development and tumor progression may also be variable. Conversely, the heterogeneous gene expression in NF may be a reflection of a relative synchronization and uniformity of gene expression in CAF.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 105.

Effect of Ultrasonic Degradation on In Vitro Antioxidant Activity of Polysaccharides from Porphyra yezoensis (Rhodophyta)

This article aims to study the effect of ultrasonic degradation on antioxidant activity of polysaccharides from Porphyra yezoensis (Rhodophyta) (PSPY), and to look for the relationship between molecular structure of fractions (F1, F2, and F3) from ultrasonic-degraded PSPY (UDPSPY) and their activities of scavenging hydroxyl and superoxide anion radicals, chelating ability of iron ion and reducing power. Results of antioxidant assays indicated that the UDPSPY had higher antioxidant activity of scavenging superoxide anion radical and hydroxyl radical than that of the PSPY. As antioxidant activities of the fractions are concerned, this result might suggest that decreasing molecular weight and increasing sulfate group content in the molecule were vital and necessary factors for improving antioxidant activity of PSPY. Decrease of molecular weight was the dominant reason for increasing activities of scavenging non-site and site specific hydroxyl radical and reducing power of F1, F2, and F3, and increase of sulfate group content in the molecule was the dominant reason for increasing activities of scavenging superoxide anion radical and chelating ferrous ions of F1, F2, and F3. It was possible that ultrasonic treatment could be a new and effective method for enhancing PSPY's antioxidant activity.

Significant alterations of biodistribution and immune responses in Balb/c mice administered with adenovirus targeted to CD40(+) cells

CD40 ligation has been shown to promote antigen-presenting functions of dendritic cells, which express CD40 receptor. Here we reported significantly altered biodistribution and immune responses with the use of CD40-targeted adenovirus. Compared with unmodified adenovirus 5, the CD40-targeted adenovirus following intravenous administration (i.v.) resulted in increased transgene expressions in the lung and thymus, which normally do not take up significant amounts of adenovirus. Intradermal injection saw modified adenovirus being mainly processed in local draining lymph nodes and skin. Following intranasal administration (i.n.), neither unmodified nor targeted viruses were found to be in the liver or spleen, which predominantly took up the virus following i.v. administration. However, inadvertent infection of the brain was found with unmodified adenoviruses, with the second highest gene expression among 14 tissues examined. Importantly, such undesirable effects were largely ablated with the use of targeted vector. Moreover, the targeted adenovirus elicited more sustained antigen-specific cellular immune responses (up to 17-fold) at later time points (30 days post boosting), but also significantly hampered humoral responses irrespective of administration routes. Additional data suggest the skewed immune responses induced by the targeted adenoviruses were not due to the identity of the transgene but more likely a combination of overall transgene load and CD40 stimulation.

A unified approach for lesion segmentation on MRI of multiple sclerosis

Accurate determination of lesion volumes on brain MR images is hampered by the presence of a large number of false positive and negative classifications. A strategy that combines parametric and nonparametric techniques is developed and implemented for minimizing the false classifications. Initially, CSF and lesions are segmented using Parzen window classifier. Image processing, morphological operations, and ratio map of proton density (PD) and T2 weighted images are used for minimizing false positives. Lesions are delineated using fuzzy connectedness principle. Contextual information was used for minimizing false negative lesion classifications. Gray and white matter classification is realized using HMRF-EM algorithm.

The relationship between polymorphisms of HCMV UL144 ORF and clinical manifestations in 73 strains with congenital and/or perinatal HCMV infection

Human cytomegalovirus (HCMV) displays genetic variability and can cause a wide range of diseases in neonates. To explore the relationship between polymorphisms and clinical manifestations, the UL144 genes from 73 clinical strains were sequenced. All of the strains, which came from 70 infants with suspected congenital and/or perinatal HCMV infection, were non-passage strains. Among them, 23 strains were from surgery specimens, and the others were from urine samples. Clinically, 12 infants displayed asymptomatic infection and 58 patients displayed symptomatic infection. The results showed that 36 patients (49.3%) were infected with strains belonging to UL144 group G1 (G1a 33/36, G1b 3/36), 19 patients (28.8%) were infected with strains belonging to group G2, and 15 patients (21.9%) were infected with strains belonging to group G3. This result indicated that UL144 group G1 was the predominant genotype in congenital and/or perinatal HCMV infection in northern China. Compared with the distribution pattern of strains in UL144 genotypes of data from Chicago, Iowa and Texas, and Japan by chi-square test, the difference was statistically significant. This suggested that the distribution pattern of strains in UL144 genotype was related to geographic location. However, no linkage was observed between the UL144 genotypes and the severity and/or outcome of HCMV disease.

Sequence variability of the human cytomegalovirus UL141 Open Reading Frame in clinical strains

Human cytomegalovirus (HCMV) displays genetic polymorphisms. HCMV disease and tissue tropism may be related to specific genomic variability among strains. This work analyzed the genetic polymorphism of UL141 open reading frame (ORF), one of the genes in HCMV UL/b' region, from 21 clinical strains. 8 previously published UL141 sequences in the GenBank were used for sequence comparison. Detailed sequence analysis showed that the UL141 gene was highly conserved at both the nucleotide and amino acid level. The coding regions were identical in size. The nucleotide and amino acid sequence identities among all strains were 96.9-100% and 97.6-100%, respectively.

Single-Crystalline Diluted Magnetic Semiconductor GaN:Mn Nanowires

Single-crystalline diluted magnetic semiconductor GaN:Mn nanowires with controlled Mn concentrations have been successfully synthesized and incorporated into devices. These nanowires exhibit Curie temperatures above room temperature, magnetoresistances near room temperature, and spin-dependent transport. The nanowires are used as building blocks for the fabrication of GaN:Mn/n-SiC based light-emitting diodes.

Characterisation of water behaviour in cellulose ether polymers using low frequency dielectric spectroscopy

The behaviour of water in hydroxypropylmethylcellulose (HPMC) K100LV, K4M, K15M, K100M, E4M, F4M and HPC polymers was characterised using low frequency dielectric spectroscopy (LFDS). Dielectric responses of 25% (w/w) HPMC K15M gels and deionised water were found to be similar at +22 and 0 degrees C. However, at -30 degrees C, a dielectric response typical of a solid was apparent. The melting of frozen water within gels was detected as increases in the magnitude of the dielectric response with increase in temperature. More than one phase transition was visible in the majority of gels studied which may be related to the presence of different states of water melting at different temperatures. In addition to polymer concentration, both polymer molecular weight and substitution level influenced the nature of the transitions. The magnitude of the dielectric response was increased in all HPMC gel systems in comparison to the response seen in deionised water. Drug addition affected the transitions occurring during the melting of ice in the gels. This may be related to the presence of ionic species in the systems. LFDS studies on cellulose ether gels have provided some interesting evidence for the existence of more than one state of water within such gel systems. The results are in good agreement with thermal analysis findings in similar gel systems.

[Bioreactor-landfill site for leaching solution treatment]

The study utilizes the system combined bioreactor with landfill site to treat leachate. The results show that the system helped the degradation of the organic pollutants in the leachate to be divided into two-phases, the hydrolytic fermentation and acid-production phases mainly occurred in the landfill site, the acidification rate was 40%-50%, the methane-production chiefly occurred in the bioreactor(UASB). It treated the leachate significantly and benefits the collection and utilization of methane gas. Also, the system accelerates the process of degrading municipal solid waste and stabilizing landfill site.

[A study on tongue cancer cell labeling using bromodeoxyuridine (BrdU) incorporation in vitro]

OBJECTIVE

The aim of this study is to evaluate of Bromodeoxyuridine (BrdU) label in the proliferation of the tongue cancer.

METHODS

The authors used 80 micrograms/ml BrdU or iododeoxyuridine (IdU) to label three cases of fresh tissue of tongue cancer and four bottles of Tca8113 cells in logarithmic growth period in vitro. They were fixed and embedded in the routine procedure, and then in serial sections. These specimens were labeled with BrdU polyclonal antibody (1:200), and PCNA monoclonal antibody (1:100), stained using immunohistochemical ABC method. The authors observed the shapes and sizes of those positive cells, counted their label indexes (LI) of BrdU- or IdU-positive cells and PCNA- positive cells respectively. Four bottles of Tca8113 cells were cultured for 1-4 days. One bottle of the cells was every day used in the experimental study about comparing the cells labeled BrdU with those of the S phase of FCM in same cultural time.

RESULTS

The positive cells generally owned a larger round nucleus, sometimes in company with sister cells. There was no difference of positive cells in these two kinds of labeling methods between the incorporation of BrdU or IdU and the expression of proliferating cell nuclear antigen (P > 0.05). The cells of S phase with FCM method were much more than that method with BrdU incorporation (P < 0.001).

CONCLUSION

The method of BrdU labeling could be used in tumor cellular proliferation studies.