Novel mutations in the
공공데이터포털
Background Breast cancer is the most common female malignancy and a major cause of death in middle-aged women. So far, germline mutations in the BRCA1 and BRCA2 genes in patients with early-onset breast and/or ovarian cancer have not been identified within the Iranian population. Methods With the collaboration of two main centres for cancer in Iran, we obtained clinical information, family history and peripheral blood from 83 women under the age of 45 with early-onset breast cancer for scanning of germline mutations in the BRCA1 and BRCA2 genes. We analysed BRCA1 exons 11 and BRCA2 exons 10 and 11 by the protein truncation test, and BRCA1 exons 2, 3, 5, 13 and 20 and BRCA2 exons 9, 17, 18 and 23 with the single-strand conformation polymorphism assay on genomic DNA amplified by polymerase chain reaction. Results Ten sequence variants were identified: five frameshifts (putative mutations – four novel); three missense changes of unknown significance and two polymorphisms, one seen commonly in both Iranian and British populations. Conclusions Identification of these novel mutations suggests that any given population should develop a mutation database for its programme of breast cancer screening. The pattern of mutations seen in the BRCA genes seems not to differ from other populations studied. Early-onset breast cancer (less than 45 years) and a limited family history is sufficient to justify mutation screening with a detection rate of over 25% in this group, whereas sporadic early-onset breast cancer (detection rate less than 5%) is unlikely to be cost-effective.
Mutation analysis of the CHK2 gene in breast carcinoma and other cancers
공공데이터포털
Background Mutations in the CHK2 gene at chromosome 22q12.1 have been reported in families with Li-Fraumeni syndrome. Chk2 is an effector kinase that is activated in response to DNA damage and is involved in cell-cycle pathways and p53 pathways. Methods We screened 139 breast tumors for loss of heterozygosity at chromosome 22q, using seven microsatellite markers, and screened 119 breast tumors with single-strand conformation polymorphism and DNA sequencing for mutations in the CHK2 gene. Results Seventy-four of 139 sporadic breast tumors (53%) show loss of heterozygosity with at least one marker. These samples and 45 tumors from individuals carrying the BRCA2 999del5 mutation were screened for mutations in the CHK2 gene. In addition to putative polymorphic regions in short mononucleotide repeats in a non-coding exon and intron 2, a germ line variant (T59K) in the first coding exon was detected. On screening 1172 cancer patients for the T59K sequence variant, it was detected in a total of four breast-cancer patients, two colon-cancer patients, one stomach-cancer patient and one ovary-cancer patient, but not in 452 healthy individuals. A tumor-specific 5' splice site mutation at site +3 in intron 8 (TTgt [a → c]atg) was also detected. Conclusion We conclude that somatic CHK2 mutations are rare in breast cancer, but our results suggest a tumor suppressor function for CHK2 in a small proportion of breast tumors. Furthermore, our results suggest that the T59K CHK2 sequence variant is a low-penetrance allele with respect to tumor growth.
Immunodetection of nmt55/p54
공공데이터포털
Background We previously identified and characterized a novel 55 kDa nuclear protein, termed nmt55/p54nrb, whose expression was decreased in a subset of human breast tumors. The objective of this study was to determine if this reduced expression in human breast tumors was attributed to the regulation of mRNA transcription or the presence of altered forms of this protein. Results Northern blot analysis and ribonuclease protection assay indicated that nmt55/p54nrb mRNA is expressed at varying levels in estrogen receptor positive (ER+) and estrogen receptor negative (ER-) human breast tumors suggesting that reduced expression of nmt55/p54nrb protein in ER- tumors was not due to transcriptional regulation. To determine if multiple protein isoforms are expressed in breast cancer, we utilized Western blot and immunohistochemical analyses, which revealed the expression of an nmt55/p54nrb protein isoform in a subset of ER+ tumors. This subset of ER+ human breast tumors expressed an altered form of nmt55/p54nrb that was undetectable with an amino-terminal specific antibody suggesting that this isoform contains alterations or modifications within the amino terminal domain. Conclusions Our study indicates that nmt55/p54nrb protein is post-transcriptionally regulated in human breast tumors leading to reduced expression in ER- tumors and the expression of an amino terminal altered isoform in a subset of ER+ tumors. The potential involvement of nmt55/p54nrb in RNA binding and pre-mRNA splicing may be important for normal cell growth and function; thus, loss or alteration of protein structure may contribute to tumor growth and progression.
Decreased expression of the mannose 6- phosphate/insulin-like growth factor-II receptor promotes growth of human breast cancer cells
공공데이터포털
Background Loss or mutation of the mannose 6-phosphate/insulin-like growth factor-II receptor (M6P/IGF2R) has been found in breast cancer. However, whether or not decreased levels of functional M6P/IGF2R directly contribute to the process of carcinogenesis needs to be further verified by functional studies. Methods In this study, using viral and ribozyme strategies we reduced the expression of M6P/IGF2R in human breast cancer cells and then examined the effect on growth and apoptosis of these cells. Results Our results showed that infection of MCF-7 cells with the adenovirus carrying a ribozyme targeted against the M6P/IGF2R mRNA dramatically reduced the level of transcripts and the functional activity of M6P/IGF2R in these cells. Accordingly, cells treated with the ribozyme exhibited a higher growth rate and a lower apoptotic index than control cells (infected with a control vector). Furthermore, decreased expression of M6P/IGF2R enhanced IGF-II-induced proliferation and reduced cell susceptibility to TNF-induced apoptosis. Conclusions These results suggest that M6P/IGF2R functions as a growth suppressor and its loss or mutation may contribute to development and progression of cancer. This study also demonstrates that adenoviral delivery of the ribozyme provides a useful tool for investigating the role of M6P/IGF2R in regulation of cell growth.
Deficiency ofPtenaccelerates mammary oncogenesis in MMTV-Wnt-1transgenic mice
공공데이터포털
Background Germline mutations in the tumor suppressor PTEN predispose human beings to breast cancer, and genetic and epigenetic alterations of PTEN are also detected in sporadic human breast cancer. Germline Pten mutations in mice lead to the development of a variety of tumors, but mammary carcinomas are infrequently found, especially in mice under the age of six months. Results To better understand the role of PTEN in breast tumor development, we have crossed Pten heterozygous mice to MMTV-Wnt-1 transgenic mice that routinely develop ductal carcinomas in the mammary gland. Female Wnt-1 transgenics heterozygous for Pten developed mammary tumors earlier than Wnt-1 transgenics that were wild type for Pten. In most tumors arising in Pten heterozygotes, the Pten wild-type allele was lost, suggesting that cells lacking Pten function have a growth advantage over cells retaining a wild type allele. Tumors with LOH contained high levels of activated AKT/PKB, a downstream target of the PTEN/PI3K pathway. Conclusions An animal model has been developed in which the absence of Pten collaborates with Wnt-1 to induce ductal carcinoma in the mammary gland. This animal model may be useful for testing therapies specific for tumors deregulated in the PTEN/PI3K/AKT pathway.
Di-, tri- and tetra-5'-
공공데이터포털
Background The human FHIT gene is inactivated early in the development of many human cancers and loss of Fhit in mouse predisposes to cancer while reintroduction of FHIT suppresses tumor formation via induction of apoptosis. Fhit protein, a diadenosine polyphosphate hydrolase, does not require hydrolase activity to function in tumor suppression and may signal for apoptosis as an enzyme-substrate complex. Thus, high affinity nonhydrolyzable substrate analogs may either promote or antagonize Fhit function, depending on their features, in Fhit + cells. Previously synthesized analogs with phosphorothioadenosyl substitutions and "supercharged" branches do not bind better than natural substrates and thus have limited potential as cellular probes. Results Here we link adenosine 5'-O-phosphates and phosphorothioates to short-chain polyols to generate a series of substrate analogs. We obtain structure-activity data in the form of in vitro Fhit inhibition for four types of analog substitutions and describe two compounds, inhibitory constants for which are 65 and 75-fold lower than natural substrates. Conclusions The best Fhit inhibitors obtained to date separate two or more 5'-O-phosphoromonothioadenosyl moieties with as many bond lengths as in AppppA, maintain oxygen at the location of the α-β bridging oxygen, and replace carbon for the β phosphorus.
Datasets for Figures and Tables in SIX1 regulates aberrant endometrial epithelial cell differentiation and cancer trajectory
공공데이터포털
Data associated with the figures presented in this study are images, graphics, or tabulated data based on histopathologic analysis performed by a certified study pathologist or image analysis. Data for Tables 1 and 2 provide incidence, labeling scores, and p-values for statistical tests for uterine pathology and IHC expression by treatment group and timepoint or human endometrial tissue, as described in the Main Text file of the manuscript. Manual histopathologic data can be found in excel spreadsheets and are based on presence/absences (yes/no) of a pathologic finding and/or severity score as described in the manuscript (Fig. 1, 2, 3, 4). The image analysis data is based on the quantified area that is designated as “positive” for a particular immunohistochemical stain (Fig. 2, 4, and Suppl. Fig. S2). Supplementary Table 1 provides summary information on antibodies used for immunohistochemistry. Supplementary fig. S1 includes real time RT-PCR data standardized to a housekeeping gene and western blot data. This dataset is associated with the following publication: Suen, A., W. Jefferson, C. Wood, and C. Williams. SIX1 regulates aberrant endometrial epithelial cell differentiation and cancer trajectory. Molecular Cancer Research. American Association for Cancer Research, Inc., Philadelphia, PA, USA, 17(12): 2369-2382, (2019).
Datasets for Figures and Tables in SIX1 regulates aberrant endometrial epithelial cell differentiation and cancer trajectory
공공데이터포털
Data associated with the figures presented in this study are images, graphics, or tabulated data based on histopathologic analysis performed by a certified study pathologist or image analysis. Data for Tables 1 and 2 provide incidence, labeling scores, and p-values for statistical tests for uterine pathology and IHC expression by treatment group and timepoint or human endometrial tissue, as described in the Main Text file of the manuscript. Manual histopathologic data can be found in excel spreadsheets and are based on presence/absences (yes/no) of a pathologic finding and/or severity score as described in the manuscript (Fig. 1, 2, 3, 4). The image analysis data is based on the quantified area that is designated as “positive” for a particular immunohistochemical stain (Fig. 2, 4, and Suppl. Fig. S2). Supplementary Table 1 provides summary information on antibodies used for immunohistochemistry. Supplementary fig. S1 includes real time RT-PCR data standardized to a housekeeping gene and western blot data. This dataset is associated with the following publication: Suen, A., W. Jefferson, C. Wood, and C. Williams. SIX1 regulates aberrant endometrial epithelial cell differentiation and cancer trajectory. Molecular Cancer Research. American Association for Cancer Research, Inc., Philadelphia, PA, USA, 17(12): 2369-2382, (2019).
Breast cancer mortality among Ashkenazi Jewish women in São Paulo and Porto Alegre, Brazil
공공데이터포털
Background Increased BRCA1 and BRCA2 germline mutation rates have been reported in Ashkenazi Jewish women in North America, Europe and Israel, and have been mentioned as possibly related to a higher incidence of breast and ovarian cancer among these communities. The present study was carried out with the aim of obtaining evidence on the magnitude of breast cancer as a cause of death among Ashkenazi women in Brazil. Methods We reviewed all death certificates archived in the Jewish Burial Societies of São Paulo (1971-1997) and Porto Alegre (1948-1997), two of the main and oldest Jewish communities in Brazil. Breast cancer observed deaths were compared with expected deaths according to breast cancer mortality in the general population. Results The observed ratios were approximately quite close to unity, suggesting a similar breast cancer mortality pattern among the Ashkenazi population and the general population in both cities. These results maintain similar behavior regardless of whether analyzed before or after the mid-1980s, when mammography came to be increasingly performed in Brazil. Cancer proportional mortality ratios were 1.04 (0.83-1.29) in São Paulo and 1.16 (0.84-1.57) in Porto Alegre before 1985, and 1.17 (1.00-1.44) and 1.21 (0.81-1.79), respectively, between 1985 and 1997. Some evidence of the maintenance of protective risk factors such as high parity has been observed among Ashkenazi women in São Paulo. Conclusion A quite similar breast cancer mortality pattern was observed between Ashkenazi Jewish women and the general population in São Paulo and Porto Alegre, Brazil. These results may suggest an environmental role on germ mutation expression reported in this ethnic group.