High Proportion Of Breast Cancers Research Articles

Abstract LB168: Blocking SIRPα on myeloid cells synergizes with radiation therapy in mouse breast cancer models

Abstract Focal tumor radiation therapy (RT) induces an immunogenic cell death associated with endogenous adjuvants that promote uptake of cancer antigens by conventional dendritic cells (cDCs). The expression of CD47 is markedly increased in a high proportion of breast cancers (BC) and correlates with poor-prognosis molecular subtypes. CD47 interaction with SIRPα expressed at the surface of cDCs and macrophages provides a negative signal that inhibits phagocytosis of dying cancer cells, hindering cross-presentation of tumor-derived antigens and activation of anti-tumor T cells. Thus, we hypothesized that the “don't-eat-me” signal mediated by CD47/SIRPα acts as a barrier to RT-induced anti-tumor immunity. Using two mouse BC models refractory to immune checkpoint blockade, we investigated the effects of RT combined with SIRPα; blockade on the development of anti-tumor immunity. BALB/c mice were inoculated subcutaneously in one or both flanks with the syngeneic TSA BC cells. RT was delivered to one tumor in 8 Gy doses on three consecutive days once tumor volume reached 60-80 mm3. SIRPα; blocking (MY1, OSAKA University [Garcia, et al. J Immunol. 2011;187:2268]) or isotype control antibodies (Abs) were given one day prior to RT and every 3 days thereafter. Some mice also received PD-L1 blocking Abs (BioXcell) every 3 days starting one day after RT completion. Mice were followed for tumor growth and splenic immune cells were analyzed by flow cytometry. Similar experiments were performed in the AT-3 mouse model of triple-negative BC (C57BL/6 background). SIRPα; blockade alone did not inhibit TSA tumor growth, but it significantly improved tumor response to RT (p<0.05), leading to complete regression of the irradiated tumor in 50-60% of the mice. In addition, the combination of SIRPα; blockade with RT significantly inhibited the growth (p<0.05) of a contralateral non-irradiated tumor (abscopal response), suggesting that it induced a systemic anti-tumor immune response. Consistent with systemic immune activation induced by SIRPα; blockade, the percentage of PD1+ CD4 T cells was increased in the spleen of mice treated with SIRPα; Abs compared to control Abs (p<0.01), regardless of RT. In the myeloid compartment, SIRPα; blockade led to a reduction in PD-L1 expression on type 2 conventional DC (cDC2) whereas cDC1 and macrophages showed increased PD-L1 expression. However, addition of anti-PD-L1 to RT+anti-SIRPα; did not further improve abscopal responses. The ability of SIRPα; blockade to significantly improve tumor control induced by RT was also seen in the AT-3 model (p<0.01).Overall, obtained results support the hypothesis that SIRPα; blockade potentiates the ability of RT to induce anti-tumor T cell responses and improve local and systemic tumor control. We are currently investigating the mechanisms of RT interaction with SIRPα; blockade to provide the rationale for translating these findings to the clinic. Citation Format: Claire Lhuillier, Maud Charpentier, Sergio Trombetta, Sandra Demaria. Blocking SIRPα on myeloid cells synergizes with radiation therapy in mouse breast cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB168.

Treating obesity as primary prevention of cancer.

e13556 Background: Prevalence of obesity in Hispanic population has been increasing. Obesity is a ‘super carcinogen’ and largely modifiable factor. We hypothesize due to current increase in prevalence of obesity there will be similar change in trend of malignancy among Hispanics and treating obesity can lead to decrease prevalence of both health conditions. Methods: National Health and Nutrition Examination Survey (NHANES) from year 1999 through 2016 was used to analyze obesity prevalence across different races. Surveillance Epidemiology and End Result (SEER) data was analyzed for racial distribution of overall and different kind of malignancies stratified by different races from 1999 through 2016. Differences of prevalence among different groups were calculated using likelihood ratio. Results: After exclusion criteria final sample size was 48,816 from NHANES and 6,868,226 from SEER dataset. Prevalence of obesity steadily increased in all races with highest change in Hispanics (31.7% in 1999-2000 to 47.3% in 2015-2016). Proportion of Hispanics with cancer also steadily increased from 7.5% in 1999-2000 to 11.3 in 2015-2016 in SEER dataset. States with high Hispanic population (New Mexico, California and New Jersey) had higher proportion of breast cancer (15.4%) compared to other states (14.5%) (p-value < 0.0001). Conclusions: Upward trend of obesity and malignancy is evident among Hispanic population. Hispanic populated states are showing higher prevalence of certain metabolically active malignancies. This increase in prevalence can be explained by “Migration Effect”. By intervening obesity 18% population attributable factor (PAF) is achievable. Opportunity exists to change this increasing trend in cancer epidemiology by treating obesity as primary prevention.

Characterization of FGD5 Expression in Primary Breast Cancers and Lymph Node Metastases.

Faciogenital dysplasia 5 ( FGD5) amplification drives tumor cell proliferation, and is present in 9.5% of breast cancers. We describe FGD5 expression, assess associations between FGD5 amplification and FGD5 expression, and assess FGD5 expression in relation to proliferation and prognosis. FGD5 immunohistochemistry was done on primary tumors ( n=829) and lymph node metastases ( n=231) from a cohort of Norwegian patients. We explored associations between FGD5 amplification, FGD5 expression, and proliferation, and analyzed the prognostic value of FGD5 expression by estimating cumulative risks of death and hazard ratios (HRs). We identified nuclear and cytoplasmic expression in 64% and 73% of primary tumors, respectively, and found an association between gene amplification and nuclear expression ( p=0.02). The proportion of cases with FGD5 expression was higher in lymph node metastases, compared with primary tumors ( p=0.004 for nuclear and p=0.001 for cytoplasmic staining). Neither proliferation nor prognosis was associated with FGD5 expression (age-adjusted HR 1.12 [95% confidence interval = 0.89-1.41] for nuclear expression; and 0.88 [95% CI = 0.70-1.12] for cytoplasmic expression). FGD5 is expressed in a high proportion of breast cancers and lymph node metastases. There was a correlation between FGD5 amplification and nuclear expression, but no association between FGD5 expression and proliferation or prognosis.

The expression of CXCL13 and its relation to unfavorable clinical characteristics in young breast cancer.

BackgroundYoung breast cancer occupies a higher and higher proportion of breast cancer, especially in Asia, and is associated with a more unfavorable prognosis compared with the disease arising in older women. However, the poor prognosis of young breast cancer cannot be fully explained by the clinical and molecular factors.MethodsThis study investigated 1125 Chinese breast cancer patients diagnosed from 2009 to 2013. A data mining of gene expression profiles was performed for the young and older breast cancer patients, identifying significantly differentially expressed genes. Quantitative RT-PCR, Western blotting and immunohistochemistry assay were carried out for the clinical sample validations.ResultsThe investigation firstly displayed that young patients (≤45 years) accounted for 47.6 % (535/1125) of breast cancer, and clinically associated with some unfavorable factors related to poor prognosis, such as invasive pathological type, high tumor grade, lymph node positive, ER negative and triple-negative subtype. Subsequently, 553 significantly differentially expressed genes were identified by the data mining. Of them, a set of genes related to immune function were observed to be up-regulated in young patients with breast cancer. Impressively, the CXCL13 (C-X-C motif chemokine 13) expression level showed the most significant difference (FC = 2.64, P = 8.2 × 10−4). Furthermore, the validations with clinical samples and correlation analysis demonstrated that CXCL13 was indeed highly expressed in young breast cancer and closely associated with some prognostic factors including lymph node positive and ER negative.ConclusionThis is the first to indicate the clinical relevance of CXCL13 to young breast cancer and represents a potential therapeutic target for young breast cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-015-0521-1) contains supplementary material, which is available to authorized users.

Assessment of diagnosis of inflammatory breast cancer cases at two cancer centers in E gypt and T unisia

The diagnosis of inflammatory breast cancer (IBC) is largely clinical and therefore inherently somewhat subjective. The objective of this study was to evaluate the diagnosis of IBC at two centers in North Africa where a higher proportion of breast cancer is diagnosed as IBC than in the United States (U.S.). Physicians prospectively enrolled suspected IBC cases at the National Cancer Institute (NCI) – Cairo, Egypt, and the Institut Salah Azaiz (ISA), Tunisia, recorded extent and duration of signs/symptoms of IBC on standardized forms, and took digital photographs of the breast. After second-level review at study hospitals, photographs and clinical information for confirmed IBC cases were reviewed by two U.S. oncologists. We calculated percent agreement between study hospital and U.S. oncologist diagnoses. Among cases confirmed by at least one U.S. oncologist, we calculated median extent and duration of signs and Spearman correlations. At least one U.S. oncologist confirmed the IBC diagnosis for 69% (39/50) of cases with photographs at the NCI-Cairo and 88% (21/24) of cases at the ISA. All confirmed cases had at least one sign of IBC (erythema, edema, peau d'orange) that covered at least one-third of the breast. The median duration of signs ranged from 1 to 3 months; extent and duration of signs were not statistically significantly correlated. From the above-mentioned outcomes, it can be concluded that the diagnosis of a substantial proportion of IBC cases is unambiguous, but a subset is difficult to distinguish from other types of locally advanced breast cancer. Among confirmed cases, the extent of signs was not related to delay in diagnosis.

Abstract PD08-06: Significant Clinical impact of recurrent BRCA1 and BRCA2 (BRCA) mutations in Mexico

Abstract Background: Breast cancer (BC) is the most commonly diagnosed cancer and the leading cancer cause of death in Hispanic women. Although the incidence of breast cancer in Hispanics is less than that for non-Hispanic white women, our studies on the prevalence of deleterious mutations in the BRCA genes among high-risk Hispanics in the US suggest that BRCA mutations may account for a higher proportion of BC in this population. However, a lack of research on BRCA mutations in Hispanics has limited the implementation of prevention efforts and the scope of comparative studies of genetic factors that influence BC and ovarian cancer (OC) risk within Hispanic populations – this is especially true of Mexico where there has been little access to clinical BRCA gene analyses. Objective/Methods: We used an economic panel assay (HISPANEL) on a mass spectroscopy platform (Sequenom) to analyze DNA from 189 cancer cases (92 unselected OC; 97 BC) from the National Cancer Institute in Mexico City for recurrent BRCA mutations, including a large rearrangement (BRCA1 ex9-12del) that we hypothesize is a Mexican founder mutation. Results: Overall, 14% (27/189) harbored a germline BRCA mutation (25 BRCA1, 2 BRCA2) detected by the HISPANEL (17% in OC; 11% in BC). BRCA1 ex9-12del was detected in 9.8% (9/92) of unselected OC cases, representing 56% of the 16 BRCA mutations. It also represented 36% (4/11) of the BRCA mutations detected in the BC cases. Mean age at onset of BC for BRCA-associated cases (n = 11) was 46 years old (range 31–63); 8/11 were triple negative BC (TNBC) – a BRCA mutation was detected in 24% (8/34) of all TNBC cases. Conclusions: The remarkable frequency of the BRCA1 ex9-12del mutation, accounting for 56% of BRCA mutations in the OC cases and 36% of BC cases, supports our hypothesis of regional origin of this Mexican founder mutation approximately 1,474 years ago. Similar to our experience in the Mexican American population, the HISPANEL, which includes recurrent BRCA mutations found in women of Hispanic ancestry, appears to have high sensitivity and thus is likely to have clinical utility while reducing overall genotyping cost among underserved women in Mexico. Both in the US Hispanic populations and in Mexico, the prevalence of the Mexican founder mutation make it a significant public health issue, and presents an opportunity for cost effective in BC and OC prevention. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD08-06.

Abstract LB-193: APOBEC3 catalyzed genomic mutations in breast cancer

Abstract In this work, we present evidence that an endogenous DNA mutating protein, APOBEC3, is massively overexpressed in a high proportion of breast cancers and that this overexpression may be responsible for the genetic variability seen in these cancers. Multiple driver mutations are required for cancer development and recent genome-wide approaches have revealed that many cancers, including breast, harbor staggering numbers of mutations, both point mutations as well as gross chromosomal rearrangements. The molecular origins of most of these somatic aberrations remain unclear. In this work, we test the hypothesis that APOBEC3, an endogenous DNA mutator, is a causative factor driving these mutations. One clue derives from the fact that C/G-to-T/A transition mutations, both within and outside of methyl-C-p-G dinucleotide motifs, predominate in subsets of many tumor types, including breast cancer. We demonstrate that APOBEC3, a DNA cytosine deaminase, is a likely endogenous source of mutation in breast cancer. We show, using quantitative reverse transcriptase PCR (qRT-PCR), that APOBEC3 is overexpressed in a majority of commonly available breast cancer cell lines (34/44) when compared to MCF-10A and hTERT-HMEC control lines. This overexpression phenotype persists when examining primary breast tumors (24/37) using patient-matched normal tissues as controls. APOBEC3 is predominantly localized to the nuclear compartment when overexpressed, as seen using fluorescently tagged APOBEC3. Additionally, its catalytic DNA cytosine to uracil deamination activity is dramatically elevated in this compartment in multiple breast cancer cell lines, as quantified using a FRET-based DNA oligonucleotide cleavage assay. This presentation will discuss the potential impact of this potent endogenous mutagen on the breast cancer genome and the implications for tumor evolution and therapy resistance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-193. doi:10.1158/1538-7445.AM2011-LB-193

42. PI3K pathway activation in breast cancer is associated with the basal-like phenotype and cancer-specific mortality

Breast cancer is a common malignancy with current therapies tailored to steroid hormone (ER, PR) and HER2 receptor status. Understanding the biological basis of resistance to current targeted therapies and the identification of new potential therapeutic targets is an ongoing challenge. The PI3K pathway is altered in a high proportion of breast cancers and may contribute to endocrine resistance. We undertook the first integrative study of mutational and expression analysis of key regulators of the PI3K pathway in a cohort of invasive breast cancer patients with known treatment outcomes. The alterations identified in our cohort of breast cancer patients included <i>PIK3CA</i> mutations 7%, i.e., 12 of 168 cancers, <i>PIK3CA</i> amplification 14%, i.e., 28 of 209 cancers, PTEN loss 28%, i.e., 73 of 258 tumours and pAKT activation 24%, i.e., 62 of 258 tumours. Overall 72%, i.e., 139 of 193 primary breast cancers, where at least one parameter was altered, had an activated PI3K pathway. PI3K pathway activation was significantly associated with negative ER (<i>p</i>=0.0008) and PR (<i>p</i>=0.006) status, high tumour grade (<i>p</i>=0.032) and a ‘basal-like' phenotype (<i>p</i>=0.030), where 92%, i.e., 25 of 27 tumours had an active pathway. In univariate analysis an activated PI3K pathway was associated with death from breast cancer; however, in multivariate analysis it was not an independent predictor of breast cancer-related death. No association was identified between an activated pathway and tamoxifen or chemotherapy-treated patients. We conclude that >70% of breast cancers have an altered PI3K pathway and this might be exploited to therapeutic advantage especially in ‘basal-like' cancers.

The role of MNK proteins and eIF4E phosphorylation in breast cancer cell proliferation and survival

eIF4E is over-expressed in many tumours, including a high proportion of breast cancers. eIF4E is an oncogene, and signalling pathways which promote eIF4E activity represent potential targets for therapeutic intervention in cancer. MNKs phosphorylate eIF4E on serine 209, a modification that can be required for eIF4E-dependent cell transformation. There is therefore a clear requirement to determine the role of MNKs in the proliferation and survival of cells from the major human tumours, such as breast cancer. Phosphorylated eIF4E protein was readily detectable in some breast tumour samples, but was below the limits of detection in others. Of 6 breast cancer cell lines representing the major sub-types of breast cancer, phosphorylated eIF4E was readily detectable in 5 of them, with MCF-7 cells displaying markedly lower levels. Long term colony forming assays demonstrated that all the five lines with high levels of phosphorylated eIF4E were highly sensitive to a MNK inhibitor. In short term assays, a range of responses was revealed. MCF-7 cells were insensitive in both assays. The anti-proliferative effects of the MNK inhibitor in breast cancer cells are primarily cytostatic, rather than cytotoxic, and are potentially due to the inhibition of cyclin D1 synthesis. Our data provide evidence that the sensitivity of breast cancer cells to MNK inhibition may correlate with baseline levels of eIF4E phosphorylation, and suggest that a proportion of breast cancers could be sensitive to inhibiting MNK kinase activity, and that the presence of phosphorylated eIF4E could provide a biomarker for the identification of responsive tumours.

PI3K Pathway Activation in Breast Cancer Is Associated with the Basal-Like Phenotype and Cancer-Specific Mortality.

Abstract Background: Current biological therapies for breast cancer are tailored to steroid hormone (ER, PR) and HER2 receptor status. Understanding the biological basis of resistance to current targeted therapies and the identification of new potential therapeutic targets is an ongoing challenge. The PI3K pathway is altered in a high proportion of breast cancers and may be associated with specific phenotypes and therapeutic resistance. We undertook an integrative study of mutational, copy number and expression analysis of key regulators of the PI3K pathway in a cohort of 292 invasive breast cancer patients with known treatment outcomes.Material and Methods: Mutations in 3 "hotspots" in exons 9 and 20 of the PIK3CA gene were determined by sequencing and PIK3CA gene copy number by qPCR. PTEN loss and Akt activation i.e. pAkt (Ser473) were assessed by immunohistochemistry using tissue microarrays. Cores were scored by 2 independent observers blinded to clinicopathological data and patient outcome and a histoscore calculated by multiplying the percent positive cells and staining intensity in a range 0-3. Standard statistical tests were applied to assess relationship between the measured parameters and patient outcome.Results: Alterations identified included PIK3CA mutations (12/168 i.e. 7%), PIK3CA copy number gain (28/209 i.e. 14%), PTEN loss (73/258 i.e. 28%) and AKT activation (62/258 i.e. 24%). Overall at least one parameter was altered in 72% i.e. 139 of 193 assessable primary breast cancers. PI3K pathway activation was significantly associated with ER negative (P=0.0008) and PR negative (P=0.006) status, high tumor grade (P=0.032) and a "basal-like" phenotype (P=0.01), where 92% (25/27) of tumors had an altered pathway. In univariate analysis PI3K pathway aberrations were associated with death from breast cancer however this relationship was not maintained in multivariate analysis. No association was identified between an activated pathway and outcome in tamoxifen- or chemotherapy-treated patients.Discussion: We conclude that &amp;gt;70% of breast cancers have an alteration in at least one component of the PI3K pathway and this might be exploited to therapeutic advantage especially in "basal-like" cancers. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2123.

PI3K pathway activation in breast cancer is associated with the basal‐like phenotype and cancer‐specific mortality

Breast cancer is a common malignancy with current biological therapies tailored to steroid hormone (ER, PR) and HER2 receptor status. Understanding the biological basis of resistance to current targeted therapies and the identification of new potential therapeutic targets is an ongoing challenge. The PI3K pathway is altered in a high proportion of breast cancers and may contribute to therapeutic resistance. We undertook an integrative study of mutational, copy number and expression analyses of key regulators of the PI3K pathway in a cohort of 292 invasive breast cancer patients with known treatment outcomes. The alterations identified in this cohort included PIK3CA mutations (12/168, i.e. 7%), PIK3CA copy number gain (28/209, i.e. 14%), PTEN loss (73/258, i.e. 28%) and AKT activation (62/258, i.e. 24%). Overall at least 1 parameter was altered in 72% (139/193) of primary breast cancers. PI3K pathway activation was significantly associated with ER negative (p = 0.0008) and PR negative (p = 0.006) status, high tumor grade (p = 0.032) and a "basal-like" phenotype (p = 0.01), where 92% (25/27) of tumors had an altered pathway. In univariate analysis, PI3K pathway aberrations were associated with death from breast cancer; however, this relationship was not maintained in multivariate analysis. No association was identified between an activated pathway and outcome in tamoxifen- or chemotherapy-treated patients. We concluded that >70% of breast cancers have an alteration in at least 1 component of the PI3K pathway and this might be exploited to therapeutic advantage especially in "basal-like" cancers.

Breast cancer associated transcriptional repressor PLU‐1/JARID1B interacts directly with histone deacetylases

The PLU-1/JARID1B nuclear protein, which is expressed in a high proportion of breast cancers, but shows restricted expression elsewhere, belongs to the ARID family of proteins, known to play important roles in development, differentiation, transcriptional regulation and chromatin remodeling. PLU-1/JARID1B is a strong transcriptional repressor, and here we show that the protein localizes in MAD bodies when cotransfected with class IIa histone deacetylases (HDACs) or N-CoR. Direct binding to class I and class IIa HDACs is demonstrated, while the interaction with N-CoR appears to be indirect. The domains involved in the HDAC4-PLU-1/JARID1B interaction were investigated in detail, and the data show that 2 PHD domains in PLU-1/JARID1B, which are involved in transcriptional repression, are also crucial for binding to a domain in the 5' region of HDAC4, overlapping the MEF-2 binding region. Physiological relevance of this interaction in the mammary gland is suggested from the observation that HDAC4 and PLU-1/JARID1B are coexpressed in the pregnant and involuting mouse mammary gland and are both silenced at lactation. Significantly, the expression of both proteins is seen in breast cancers.

Induction of spermidine/spermine N1-acetyltransferase in breast cancer tissues treated with the polyamine analogue N1, N11-diethylnorspermine.

The polyamine analogue, N1, N11-diethylnorspermine (DENSpm), is currently being evaluated in clinical trials for the treatment of solid tumors. The response of solid tumors to this drug has been associated with superinduction of the polyamine catabolic enzyme, spermine/spermidine N1-acetyltransferase (SSAT). Therefore, to estimate the response of breast cancers to DENSpm, we measured induction of SSAT in breast cancer explants treated in vitro with this polyamine analogue. Expression of SSAT protein was evaluated by immunohistochemistry in tissue explants from 38 invasive breast cancer tumors incubated in vitro in the presence (or absence) of DENSpm. In addition, SSAT enzymatic activity was measured in tissue explants from four tumors with high cellularity. SSAT expression was significantly increased in 30 of 38 tumor samples treated with DENSpm compared to untreated controls. This induction of SSAT protein expression was found specifically in neoplastic cells of the treated samples, and was seen in all histologic patterns (ductal, lobular, and mucinous) of breast cancer examined. In tumor samples evaluated for changes in SSAT enzymatic activity, these changes correlated closely with changes in protein expression. Immunohistochemical staining for induction of SSAT correlates with measures of enzymatic activity in a small sample where measurements were possible and suggests that immunohistochemistry may be used for predicting response of breast cancers to DENSpm. A high proportion of breast cancers induced SSAT in response to DENSpm, supporting the continued consideration of this class of agents for treatment of breast cancer.

Overexpression of Cyclooxygenase-2 Is Associated with Breast Carcinoma and Its Poor Prognostic Factors

Cyclooxygenase is the rate-limiting enzyme that catalyzes the conversion of arachidonic acid to prostaglandins. The inducible form, cyclooxygenase-2, is known to be overexpressed in various human cancers including the colon, stomach, and urinary bladder. In this study, we evaluated the overexpression of cyclooxygenase-2 in 64 cases of breast cancer and correlated the results with clinicopathologic parameters. Immunohistochemical staining for cyclooxygenase-2 demonstrated positivity of the tumor cells in 46 of 64 cases (72%). Cyclooxygenase-2 overexpression was significantly correlated with larger tumor size and advanced clinical stage. Cyclooxygenase-2 overexpression tended to be more frequently observed in cases with presence of lymph node metastasis and in cases without expression of estrogen and progesterone; however, there was no significant correlation statistically. Nuclear and histologic grade were not well correlated with cyclooxygenase-2 overexpression. When ductal carcinoma in situ was considered separately, 32 of 42 cases (76%) were positive for cyclooxygenase-2. We conclude that cyclooxygenase-2 is up-regulated in a high proportion of breast cancers. The overexpression of cyclooxygenase-2 was associated with larger tumor size and advanced clinical stage, although lymph node status, estrogen and progesterone expression, and nuclear and histologic grade were not significantly correlated. Therefore, cyclooxygenase-2 overexpression may be a feature of the aggressive phenotype and may be useful as a prognostic indicator in breast cancer.

High frequency of p53 gene mutations in primary breast cancers in Japanese women, a low-incidence population

The pattern of acquired mutations in the p53 tumour-suppressor gene is potentially useful for determining factors contributing to carcinogenesis in diverse populations differing in incidence and/or mortality from the disease. We previously reported differences in mutational patterns of the p53 gene in primary breast cancers from Midwest US Caucasian, African-American and Austrian women. Herein, we report 16 mutations in 27 primary breast cancers from Japanese women from Hirosaki, a population with a low incidence of breast cancer. The frequency of 59.3% of p53 mutations is the highest reported in breast cancers from a particular ethnic group thus far. A relatively high number of mutations (7/16) were heterozygous in at least some tumour cell clusters. Intergroup comparisons of the mutational pattern between this population and several other US, European and Japanese populations do not show any statistically significant differences. There were recurrent mutations at two sites, codon 273 (R --> H; three mutations), a common hotspot of mutations in breast and other cancers, and codon 183 (S --> Stop; two mutations), a very rare location for p53 mutations. These mutations were shown to be independent and presumably not in the germ line. The highest frequency of p53 mutations raises the possibility that p53 mutagenesis is a predominant factor for breast cancer development in this low-risk Japanese group, whereas in other cohorts different mechanisms are likely to account for the higher proportion of breast cancer. Further studies are needed to confirm the present observations.

Failure to detect gonadotrophin-releasing hormone receptors in human benign and malignant breast tissue and in MCF-7 and MDA-MB-231 cancer cells

We have measured the binding of radiolabelled analogues of gonadotrophin-releasing hormone (GnRH) to homogenates of human breast cancer and benign breast tissue, and to MCF-7 and MDA-MB-231 cell lines. Although incubation of breast cancer homogenates with the 125I-labelled GnRH agonist analogues, buserelin [(D-Ser tBU 6)GnRH 1–9 ethylamide] and tryptorelin [(D-Trp 6) GnRH 1–9 ethylamide] appeared to show significant though low, specific GnRH agonist binding in a high proportion of breast cancers ( 32 42 for buserelin; 15 32 for tryptorelin) and benign breast tissues ( 13 16 for buserelin; 10 12 for tryptorelin), after correction for displaceable binding in control assay tubes, GnRH agonist binding to breast tissue was no longer apparent. The lack of specific binding was not due to inactivation of GnRH agonist tracers, as >86% of the unbound tracer was still capable of rebinding to fresh placental membranes after incubation with breast cancer homogenates. GnRH agonist did not bind to MCF-7 and MDA-MB-231 cells, however GnRH agonist tracer inactivation following exposure to these cells was very high. We have shown recently that human placental receptors bound salmon GnRH and chicken GnRH II as well as GnRH agonists, but not other isoforms of GnRH. However, no isoform of GnRH bound significantly to human breast tumour tissue. In summary, we could not confirm the presence of specific GnRH binding sites in homogenates and membranes from human breast tissues in this study. Low levels of apparently specific binding of GnRH agonist tracers could be accounted for entirely by displacement of tracer from assay tubes. Inability to demonstrate specific binding was not due to extensive inactivation of GnRH tracers (although this may be a factor in the failure to demonstrate GnRH binding to MCF-7 and MDA-MB-231 cell lines).

469 Reversible pharmacological castration with the LH-RH-agonist buserelin: Results in endometriosis

We have measured the binding of radiolabelled analogues of gonadotrophin-releasing hormone (GnRH) to homogenates of human breast cancer and benign breast tissue, and to MCF-7 and MDA-MB-231 cell lines. Although incubation of breast cancer homogenates with the 125I-labelled GnRH agonist analogues, buserelin [(D-Ser tBU6)GnRH 1–9 ethylamide] and tryptorelin [(D-Trp6) GnRH 1–9 ethylamide] appeared to show significant though low, specific GnRH agonist binding in a high proportion of breast cancers (3242 for buserelin; 1532 for tryptorelin) and benign breast tissues (1316 for buserelin; 1012 for tryptorelin), after correction for displaceable binding in control assay tubes, GnRH agonist binding to breast tissue was no longer apparent. The lack of specific binding was not due to inactivation of GnRH agonist tracers, as >86% of the unbound tracer was still capable of rebinding to fresh placental membranes after incubation with breast cancer homogenates. GnRH agonist did not bind to MCF-7 and MDA-MB-231 cells, however GnRH agonist tracer inactivation following exposure to these cells was very high. We have shown recently that human placental receptors bound salmon GnRH and chicken GnRH II as well as GnRH agonists, but not other isoforms of GnRH. However, no isoform of GnRH bound significantly to human breast tumour tissue.In summary, we could not confirm the presence of specific GnRH binding sites in homogenates and membranes from human breast tissues in this study. Low levels of apparently specific binding of GnRH agonist tracers could be accounted for entirely by displacement of tracer from assay tubes. Inability to demonstrate specific binding was not due to extensive inactivation of GnRH tracers (although this may be a factor in the failure to demonstrate GnRH binding to MCF-7 and MDA-MB-231 cell lines).

Value of mammography in reduction of mortality from breast cancer in mass screening.

A randomized mass screening program using mammography as well as clinical examination in women aged 40 to 64 years resulted in a higher proportion of breast cancer detected with no axillary lymph node involvement and subsequently a substantial reduction in mortality in a study group as compared to a matched control. Both clinical examination and mammography contributed independently to the yield. However, in women under 50 in this study, mammography led to detection of only a small proportion of additional cases, while at age 50 years and over omission of either modality would have led to substantially lower cancer detection rates. The particularly substantial contribution of mammography is underscored by a case fatality rate of only 2 per cent in cancers detected in mammography alone.It would be reasonable to conclude that further follow-up to determine long-term effect of the screening procedures is indicated.It would also seem useful to evaluate the contribution of newer improved methods of mammography...