Identification of a novel truncating PALB2 mutation and analysis of its contribution to early-onset breast cancer in French-Canadian women

Background

PALB2 has recently been identified as a breast cancer susceptibility gene. PALB2 mutations are rare causes of hereditary breast cancer but may be important in countries such as Finland where a founder mutation is present. We sought to estimate the contribution of PALB2 mutations to the burden of breast cancer in French Canadians from Quebec.

Methods

We screened all coding exons of PALB2 in a sample of 50 French-Canadian women diagnosed with either early-onset breast cancer or familial breast cancer at a single Montreal hospital. The genetic variants identified in this sample were then studied in 356 additional women with breast cancer diagnosed before age 50 and in 6,448 newborn controls.

Results

We identified a single protein-truncating mutation in PALB2 (c.2323 C>T, resulting in Q775X) in 1 of the 50 high-risk women. This variant was present in 2 of 356 breast cancer cases and in none of 6,440 newborn French-Canadian controls (P = 0.003). We also identified two novel new non-synonymous single nucleotide polymorphisms in exon 4 of PALB2 (c.5038 A>G [I76V] and c.5156 G>T [G115V]). G115V was found in 1 of 356 cases and in 15 of 6,442 controls (P = 0.6). The I76V variant was not identified in either the extended case series or the controls.

Conclusion

We have identified a novel truncating mutation in PALB2. The mutation was found in approximately 0.5% of unselected French-Canadian women with early-onset breast cancer and appears to have a single origin. Although mutations are infrequent, PALB2 can be added to the list of breast cancer susceptibility genes for which founder mutations have been identified in the French-Canadian population.     

PIK3CA-activating mutations and chemotherapy sensitivity in stage II–III breast cancer

Introduction

In vitro evidence suggests that PIK3CA (phosphatidylinositol 3-kinase, catalytic, alpha polypeptide) activation may be associated with altered chemotherapy sensitivity in cancer.

Methods

Tumor DNA from 140 patients with stage II–III breast cancer undergoing neoadjuvant chemotherapy was sequenced for PIK3CA mutations on exons 1, 9, and 20. Mutation status was correlated with clinical/pathological parameters and chemotherapy response as (a) pathological complete response (pCR) versus residual cancer or (b) quantitative residual cancer burden (RCB) scores, including stratification for estrogen receptor (ER) expression status, type of chemotherapy, and by exons.

Results

Twenty-three patients (16.4%) harbored a PIK3CA mutation, with 12, 11, and 0 mutations located in exons 9, 20, and 1, respectively. PIK3CA exon 9 mutations were more frequent among node-negative (52% versus 25%; P = 0.012) than node-positive tumors, particularly among ER-positive tumors. pCR rates and RCB scores were similar among patients with the wild-type and mutant PIK3CA genes, even after stratification by ER status, chemotherapy regimen (anthracycline versus anthracycline plus paclitaxel), or exon.

Conclusion

PIK3CA mutations are not associated with altered sensitivity to preoperative anthracycline-based or taxane-based chemotherapies in ER-positive and ER-negative breast tumors. In this study, PIK3CA mutation was associated with a decreased rate of node-positive disease, particularly among ER-positive tumors.     

Tumor DNA in plasma of breast cancer patients. Relation to treatment

Background

The present study was designed to investigate the possible impact of treatment on changes in plasma DNA showing tumor DNA features in breast cancer patients.

Methods

Thirty-eight patients were included. DNA extracted from tumor and normal tissues, normal blood cells, and plasma was used for molecular studies. Molecular alterations in six polymorphic markers (TH2, D10S197, D16S421, D17S855, D17S654, D9S161), mutations in TP53, and aberrant methylation of the first exon of p16^INK4a were used to characterize tumor and plasma DNA. After mastectomy, 26 patients received adjuvant chemotherapy and 12, hormone therapy.

Results

At least one molecular alteration was detected in 28 tumors, and 9 patients showed more than one concomitant molecular change. Twenty patients (53%) displayed loss of heterozygosity (LOH), 6 (16%) TP53 mutations and 11 (29%) methylation of the first exon of p16^INK4a. The same molecular aberration was observed in plasma DNA of 18 patients (14 receiving chemotherapy and 4 hormone therapy). Six months after mastectomy, these molecular alterations persisted in the plasma DNA of 6 patients (5 who had completed adjuvant chemotherapy and 1 under hormone therapy).

Conclusions

Circulating plasma DNA present after mastectomy is modified only partially by adjuvant chemotherapy or hormone therapy.     

Amphiregulin and Epiregulin mRNA expression in primary colorectal cancer and corresponding liver metastases

Background

A single nucleotide polymorphism located in the 3'-untranslated region of the KRAS oncogene (KRAS variant; rs61764370) disrupts a let-7 miRNA binding and was recently reported to act as a genetic marker for increased risk of developing human cancers. We aimed to investigate an association of the KRAS variant with sporadic and familial breast cancer and breast tumor characteristics.

Methods

Genotyping was accomplished in 530 sporadic postmenopausal breast cancer cases, 165 familial breast cancer cases (including N = 29, who test positive for BRCA1/2 mutations) and 270 postmenopausal control women using the flurogenic 5' nuclease assay. Information on hormone replacement therapy (HRT) use and tumor characteristics in sporadic breast cancer cases was ascertained from a postal questionnaire and pathology reports, respectively. Associations between the KRAS genotype and breast cancer or breast tumor characteristics were assessed using chi-square test and logistic regression models.

Results

No evidence of association was observed between the KRAS variant and risk of sporadic and familial breast cancer - either among BRCA carriers or non-BRCA carriers. The KRAS variant was statistically significantly more often associated with human epidermal growth factor receptor 2 (HER2) - positive tumors and tumors of higher histopathologic grade. However, both associations were detected only in HRT users.

Conclusion

Our data do not support the hypothesis that the KRAS variant rs61764370 is implicated in the aetiology of sporadic or of familial breast cancer. In postmenopausal women using HRT, the KRAS variant might lead to HER2 overexpressed and poorly-differentiated breast tumors, both indicators of a worse prognosis.     

The intronic G13964C variant in p53 is not a high-risk mutation in familial breast cancer in Australia

Background

Mutations in BRCA1 and BRCA2 account for approximately 50% of breast cancer families with more than four affected cases, whereas exonic mutations in p53, PTEN, CHK2 and ATM may account for a very small proportion. It was recently reported that an intronic variant of p53 - G13964C - occurred in three out of 42 (7.1%) 'hereditary' breast cancer patients, but not in any of 171 'sporadic' breast cancer control individuals (P = 0.0003). If this relatively frequent occurrence of G13964C in familial breast cancer and absence in control individuals were confirmed, then this would suggest that the G13964C variant plays a role in breast cancer susceptibility.

Method

We genotyped 71 familial breast cancer patients and 143 control individuals for the G13964C variant using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) analysis.

Results

Three (4.2%; 95% confidence interval [CI] 0–8.9%) G13964C heterozygotes were identified. The variant was also identified in 5 out of 143 (3.5%; 95% CI 0.6–6.4%) control individuals without breast cancer or a family history of breast cancer, however, which is no different to the proportion found in familial cases (P = 0.9).

Conclusion

The present study would have had 80% power to detect an odds ratio of 4.4, and we therefore conclude that the G13946C polymorphism is not a 'high-risk' mutation for familial breast cancer.     

Low prevalence of GJB2 mutations in non-syndromic hearing loss in Western India

Objectives

To identify the prevalence of GJB2 (Cx 26)and GJB6 (Cx 30) mutations in hearing impaired individuals from Western and South India.

Study design

Cross-sectional study.

Methods

Families with hearing impaired individuals (prelingual, non-syndromic, sensori-neural hearing loss) were enrolled and genomic DNA was extracted. Primers were designed for amplifying the coding and non-coding exons including flanking splice sites of the Cx 26 gene. Probands heterozygous or negative for Cx 26 mutations were further analyzed for the 342Kb deletion encompassing D13S1830 microsatellite marker on Cx 30.

Results

Two hundred and eighty-eight patients were enrolled in the study and 116 (40.3%) were diagnosed to have mutations in the coding exon 2 of Cx 26 gene. Fifty-four (18.8%) probands were found to have mutations in both the alleles while the remaining 62 (21.5%) were heterozygous for Cx 26 mutations. W24X, and W77X were the common mutations identified. The prevalence of familial deafness was similar in both consanguineous and non-consanguineous families (33% and 34.9% respectively). Mutations in the non-coding exon 1 and intron 1 as well as the 342 kb deletion involving D13S1830 marker on Cx 30 were ruled out in two hundred and thirty-four deaf individuals carrying none or only one mutation in the exon 2 of Cx 26 gene.

Conclusion

Cx30 mutations do not contribute to the autosomal recessive non-syndromic hearing loss (NSHL) in the Indian population. Homozygous Cx26 mutations account only for about 1/5th (18.8%) of autosomal recessive non-syndromic hearing implying the need to explore other contributory loci.     

Comparable frequency of BRCA1, BRCA2 and TP53 germline mutations in a multi-ethnic Asian cohort suggests TP53 screening should be offered together with BRCA1/2 screening to early-onset breast cancer patients

Introduction

Germline TP53 mutations cause an increased risk to early-onset breast cancer in Li-Fraumeni syndrome (LFS) families and the majority of carriers identified through breast cancer cohorts have LFS or Li-Fraumeni-like (LFL) features. However, in Asia and in many low resource settings, it is challenging to obtain accurate family history and we, therefore, sought to determine whether the presence of early-onset breast cancer is an appropriate selection criteria for germline TP53 testing.

Methods

A total of 100 patients with early-onset breast cancer (?? 35 years) treated at University Malaya Medical Centre between 2003 and 2009, were analyzed for germline mutations in BRCA1, BRCA2 and TP53 by full DNA sequencing. Of the mutations identified, we examined their likely pathogenicity on the basis of prevalence in a case-control cohort, co-segregation analyses and loss of heterozygosity (LOH) in tumor tissues.

Results

We identified 11 BRCA1 (11%) and 6 BRCA2 (6%) germline carriers among early-onset breast cancer patients. Of the 83 BRCA-negative patients, we identified four exonic variants and three intronic variants in TP53. Of these, two exonic variants are clinically relevant (E346X and p. G334_R335dup6) and two novel missense mutations (A138V and E285K) are likely to be clinically relevant, on the basis of co-segregation and loss of heterozygosity (LOH). Notably, E285K was found in two unrelated individuals and haplotype analyses suggest a founder effect. Two of the three intronic variants are likely benign based on their prevalence in a control population. Clinically relevant TP53 germline mutations were identified in three of the four patients (75%) with a family history of at least two LFS-linked cancers (breast, bone or soft tissue sarcoma, brain tumors or adrenocortical cancer); 1 of the 17 patients (6%) with a family history of breast cancer only, and 1 of the 62 patients (< 2%) with no family history of breast or LFS-linked cancers.

Conclusions

Our study reports germline BRCA1, BRCA2 and TP53 mutations are found in early-onset breast cancer patients at 11%, 6% and 5% respectively, suggesting that TP53 mutation screening should be considered for these patients. However, we find that even in low resource Asian settings where family history is poorly reported, germline TP53 mutations are found predominantly among breast cancer patients with a family history of LFS-linked cancers.     

Relevance of PTEN loss in brain metastasis formation in breast cancer patients

Introduction

With the improvement of therapeutic options for the treatment of breast cancer, the development of brain metastases has become a major limitation to life expectancy in many patients. Therefore, our aim was to identify molecular markers associated with the development of brain metastases in breast cancer.

Methods

Patterns of chromosomal aberrations in primary breast tumors and brain metastases were compared with array-comparative genetic hybridization (CGH). The most significant region was further characterized in more detail by microsatellite and gene-expression analysis, and finally, the possible target gene was screened for mutations.

Results

The array CGH results showed that brain metastases, in general, display similar chromosomal aberrations as do primary tumors, but with a notably higher frequency. Statistically significant differences were found at nine different chromosomal loci, with a gain and amplification of EGFR (7p11.2) and a loss of 10q22.3-qter being among the most significant aberrations in brain metastases (P < 0.01; false discovery rate (fdr) < 0.04). Allelic imbalance (AI) patterns at 10q were further verified in 77 unmatched primary tumors and 21 brain metastases. AI at PTEN loci was found significantly more often in brain metastases (52%) and primary tumors with a brain relapse (59%) compared with primary tumors from patients without relapse (18%; P = 0.003) or relapse other than brain tumors (12%; P = 0.006). Loss of PTEN was especially frequent in HER2-negative brain metastases (64%). Furthermore, PTEN mRNA expression was significantly downregulated in brain metastases compared with primary tumors, and PTEN mutations were frequently found in brain metastases.

Conclusions

These results demonstrate that brain metastases often show very complex genomic-aberration patterns, suggesting a potential role of PTEN and EGFR in brain metastasis formation.     

Molecular evaluation of <Emphasis Type="Italic">PIK3CA</Emphasis> gene mutation in breast cancer: determination of frequency,distribution pattern and its association with clinicopathological findings in Indian patients

Somatic mutations in the PIK3CA gene are common in breast cancer and represent a clinically useful marker for prognosis and therapeutic target. Activating mutations in the PI3K p110 catalytic subunit (PIK3CA) have been identified in 18–40 % of breast carcinomas. In this study, we evaluated PIK3CA mutation in 185 Indian breast cancer patients by direct DNA sequencing. PIK3CA mutations were observed in 23.2 % (43/185) of breast tumor samples. PIK3CA mutations were more frequent exon 30 (76.8 %) than in exon 9 (23.2 %). Mutations were mostly clustered within two hotspot region between nucleotides 1624 and 1636 or between 3129 and 3140. Sequencing analysis revealed four different missense mutations at codon 542 and 545 (E542K, E545K, E545A and E545G) in the helical domain and two different amino acid substitutions at codon 1047 (H1047R and H1047L) in the kinase domain. None of the cases harbored concomitant mutations at multiple codons. PIK3CA mutations were more frequent in older patients, smaller size tumors, ductal carcinomas, grade II tumors, lymph node-positive tumors and non-DCIS tumors; however, none of the differences were significant. In addition, PIK3CA mutations were common in ER+, PR+ and HER2+ cases (30 %), and a comparatively low frequency were noted in triple-negative tumors (13.6 %). In conclusion, to our knowledge, this is the largest study to evaluate the PIK3CA mutation in Indian breast cancer patients. The frequency and distribution pattern of PIK3CA mutations is similar to global reports. Furthermore, identification of molecular markers has unique strengths and can provide insights into the pathogenic process of breast carcinomas.     

Mutation analysis of FANCD2, BRIP1/BACH1, LMO4 and SFN in familial breast cancer

Introduction

Mutations in known predisposition genes account for only about a third of all multiple-case breast cancer families. We hypothesized that germline mutations in FANCD2, BRIP1/BACH1, LMO4 and SFN may account for some of the unexplained multiple-case breast cancer families.

Methods

The families used in this study were ascertained through the Kathleen Cuningham Foundation Consortium for Research into Familial Breast Cancer (kConFab). Denaturing high performance liquid chromatography (DHPLC) analysis of the coding regions of these four genes was conducted in the youngest affected cases of 30 to 267 non-BRCA1/2 breast cancer families. In addition, a further 399 index cases were also screened for mutations in two functionally significant regions of the FANCD2 gene and 253 index cases were screened for two previously reported mutations in BACH1 (p. P47A and p. M299I).

Results

DHPLC analysis of FANCD2 identified six silent exonic variants, and a large number of intronic variants, which tagged two common haplotypes. One protein truncating variant was found in BRIP1/BACH1, as well as four missense variants, a silent change and a variant in the 3' untranslated region. No missense or splice site mutations were found in LMO4 or SFN. Analysis of the missense, silent and frameshift variants of FANCD2 and BACH1 in relatives of the index cases, and in a panel of controls, found no evidence suggestive of pathogenicity.

Conclusion

There is no evidence that highly penetrant exonic or splice site mutations in FANCD2, BRIP1/BACH1, LMO4 or SFN contribute to familial breast cancer. Large scale association studies will be necessary to determine whether any of the polymorphisms or haplotypes identified in these genes contributes to breast cancer risk.     

Rare variants in the ATM gene and risk of breast cancer

Introduction

The ataxia-telangiectasia mutated (ATM) gene (MIM ID 208900) encodes a protein kinase that plays a significant role in the activation of cellular responses to DNA double-strand breaks through subsequent phosphorylation of central players in the DNA damage-response pathway. Recent studies have confirmed that some specific variants in the ATM gene are associated with increased breast cancer (BC) risk. However, the magnitude of risk and the subset of variants that are pathogenic for breast cancer remain unresolved.

Methods

To investigate the role of ATM in BC susceptibility, we studied 76 rare sequence variants in the ATM gene in a case-control family study of 2,570 cases of breast cancer and 1,448 controls. The variants were grouped into three categories based on their likely pathogenicity, as determined by in silico analysis and analyzed by conditional logistic regression. Likely pathogenic sequence variants were genotyped in 129 family members of 27 carrier probands (15 of which carried c.7271T > G), and modified segregation analysis was used to estimate the BC penetrance associated with these rare ATM variants.

Results

In the case-control analysis, we observed an odds ratio of 2.55 and 95% confidence interval (CI, 0.54 to 12.0) for the most likely deleterious variants. In the family-based analyses, the maximum-likelihood estimate of the increased risk associated with these variants was hazard ratio (HR) = 6.88 (95% CI, 2.33 to 20.3; P = 0.00008), corresponding to a 60% cumulative risk of BC by age 80 years. Analysis of loss of heterozygosity (LOH) in 18 breast tumors from women carrying likely pathogenic rare sequence variants revealed no consistent pattern of loss of the ATM variant.

Conclusions

The risk estimates from this study suggest that women carrying the pathogenic variant, ATM c.7271T > G, or truncating mutations demonstrate a significantly increased risk of breast cancer with a penetrance that appears similar to that conferred by germline mutations in BRCA2.     

The prevalence of BRCA1 mutations among young women with triple-negative breast cancer

Background

Molecular screening for BRCA1 and BRCA2 mutations is now an established component of risk evaluation and management of familial breast cancer. Features of hereditary breast cancer include an early age-of-onset and over-representation of the 'triple-negative' phenotype (negative for estrogen-receptor, progesterone-receptor and HER2). The decision to offer genetic testing to a breast cancer patient is usually based on her family history, but in the absence of a family history of cancer, some women may qualify for testing based on the age-of-onset and/or the pathologic features of the breast cancer.

Methods

We studied 54 women who were diagnosed with high-grade, triple-negative invasive breast cancer at or before age 40. These women were selected for study because they had little or no family history of breast or ovarian cancer and they did not qualify for genetic testing using conventional family history criteria. BRCA1 screening was performed using a combination of fluorescent multiplexed-PCR analysis, BRCA1 exon-13 6 kb duplication screening, the protein truncation test (PTT) and fluorescent multiplexed denaturing gradient gel electrophoresis (DGGE). All coding exons of BRCA1 were screened. The two large exons of BRCA2 were also screened using PTT. All mutations were confirmed with direct sequencing.

Results

Five deleterious BRCA1 mutations and one deleterious BRCA2 mutation were identified in the 54 patients with early-onset, triple-negative breast cancer (11%).

Conclusion

Women with early-onset triple-negative breast cancer are candidates for genetic testing for BRCA1, even in the absence of a family history of breast or ovarian cancer.     

Contribution of <Emphasis Type="Italic">BRCA1</Emphasis> large genomic rearrangements to early-onset and familial breast/ovarian cancer in Pakistan

Background

Germline mutations in BRCA1 and BRCA2 (BRCA1/2) account for the majority of hereditary breast and/or ovarian cancers. Pakistan has one of the highest rates of breast cancer incidence in Asia, where BRCA1/2 small-range mutations account for 17% of early-onset and familial breast/ovarian cancer patients. We report the first study from Pakistan evaluating the prevalence of BRCA1/2 large genomic rearrangements (LGRs) in breast and/or ovarian cancer patients who do not harbor small-range BRCA1/2 mutations.

Materials and methods

Both BRCA1/2 genes were comprehensively screened for LGRs using multiplex ligation-dependent probe amplification in 120 BRCA1/2 small-range mutations negative early-onset or familial breast/ovarian cancer patients from Pakistan (Group 1). The breakpoints were characterized by long-range PCR- and DNA-sequencing analyses. An additional cohort of 445 BRCA1/2 negative high-risk patients (Group 2) was analyzed for the presence of LGRs identified in Group 1.

Results

Three different BRCA1 LGRs were identified in Group 1 (4/120; 3.3%), two of these were novel. Exon 1–2 deletion was observed in two unrelated patients: an early-onset breast cancer patient and another bilateral breast cancer patient from a hereditary breast cancer (HBC) family. Novel exon 20–21 deletion was detected in a 29-year-old breast cancer patient from a HBC family. Another novel exon 21–24 deletion was identified in a breast-ovarian cancer patient from a hereditary breast and ovarian cancer family. The breakpoints of all deletions were characterized. Screening of the 445 patients in Group 2 for the three LGRs revealed ten additional patients harboring exon 1–2 deletion or exon 21–24 deletion (10/445; 2.2%). No BRCA2 LGRs were identified.

Conclusions

LGRs in BRCA1 are found with a considerable frequency in Pakistani breast/ovarian cancer cases. Our findings suggest that BRCA1 exons 1–2 deletion and exons 21–24 deletion should be included in the recurrent BRCA1/2 mutations panel for genetic testing of high-risk Pakistani breast/ovarian cancer patients.

     

A common missense variant in BRCA2 predisposes to early onset breast cancer

Introduction

Mutations in the BRCA2 gene are one of the two major causes of hereditary breast cancer. Protein-truncating mutations of BRCA2 are usually deleterious and increase the risk of breast cancer up to 80% over a lifetime. A few missense mutations in BRCA2 are believed to have a similarly high penetrance, apart from more common neutral polymorphisms. It is often difficult to classify a particular sequence variant as a mutation or a polymorphism. For a deleterious variant, one would expect a greater allele frequency in breast cancer cases than in ethnic-matched controls. In contrast, neutral polymorphic variants should be equally frequent in the two groups.

Methods

We genotyped 3,241 cases of breast cancer diagnosed at under 51 years of age, unselected for family history, from 18 hospitals throughout Poland and 2,791 ethnic-matched controls for a single BRCA2 C5972T variant.

Results

The variant was present in approximately 6% of the Polish population. In the study, 13 women (11 cases and two controls (OR = 4.7; p = 0.02)) were homozygous for the variant allele. The overall odds ratio for breast cancer in women with a single copy of the BRCA2 C5972T variant was 1.1 (p = 0.7); however, the effect was significant for patients diagnosed at or before age 40 (OR = 1.4; p = 0.04). We reviewed the association between the BRCA2 variant in different histologic subgroups and found the effect most pronounced in women who had ductal carcinoma in situ (DCIS) with micro-invasion (OR = 2.8; p < 0.0001).

Conclusion

The BRCA2 C5972T allele is a common variant in Poland that increases the risk of DCIS with micro-invasion. The homozygous state is rare but increases the risk of breast cancer five-fold.     

Germline mutations of PALB2 gene in a sequential series of Chinese patients with breast cancer

Background

PALB2 (Partner and Localizer of BRCA2) is recently recognized as a breast cancer predisposition gene. Germline loss-of-function mutations in PALB2 lead to increased breast cancer risk. Since the germline mutation frequency of PALB2 is much less than BRCA1/2, the distinct mutation spectrum of PALB2 is still obscure. To verify the utility of PALB2 genetic testing in Chinese population, we assessed the mutational frequency, spectrum, and predictors of the PALB2 gene in a sequential series of Chinese breast cancer patients from our Research DNA Bank.

Methods

We examined breast cancer samples (n = 2279) collected from 2000 through 2016 from Chinese patients who agreed to participate in research DNA banking. To identify the mutations, complete coding sequence and intron–exon boundaries of PALB2 were screened with Next-Generation Sequencing. Personal and family histories were synchronously collected for mutation identification.

Results

Among the 2279 breast cancer patients, 305 patients were familial breast cancer cases and the rest 1967 patients were sporadic breast cancer cases. PALB2 loss-of-function mutation carriers accounted for 1.31% (n = 4) and 0.56% (n = 11) in familial and sporadic breast cancer cohort separately. In total, 30 missenses, four nonsenses, three frameshifts, three splicings, and one inframe deletions of PALB2 were identified in this study. Among the deleterious mutations, PALB2 c.1744C>T, c.2748+1G>A, c.2749?1G>C, c.3114?1G>A were newly identified in sporadic breast cancer, and c.3271delC newly found in familial breast cancer. Based on in silico analysis, we found two potentially damaging missense variants with high frequency: c.1213C>G, c.3054G>C, and classified six new potentially damaging missense variants.

Conclusions

Our data presented the germline mutation status of PALB2 in Chinese breast cancer patients, suggesting that loss-of-function germline mutations of PALB2 are important in both familial and sporadic breast cancer. Clinically, these data may be helpful in genetic counseling of breast cancer patients with PALB2 germline mutation.

     

Inhibition of CCN6 (WISP3) expression promotes neoplastic progression and enhances the effects of insulin-like growth factor-1 on breast epithelial cells

Introduction

Evidence suggests that alterations in estrogen signaling pathways, including estrogen receptor-α (ER-α), occur during breast cancer development. A point mutation in ER-α (nucleotide A908G), producing an amino acid change from lysine to arginine at codon 303 (K303R) results in receptor hypersensitivity to estrogen. This mutation was initially reported in one-third of hyperplastic benign breast lesions, although several recent studies failed to detect it in benign or malignant breast tissues.

Methods

We screened 653 microdissected, newly diagnosed invasive breast tumors from patients in the Carolina Breast Cancer Study, a population-based case-control study of breast cancer in African American and white women in North Carolina, for the presence of the ER-α A908G mutation by using single-strand conformational polymorphism (SSCP) analysis and ³³P-cycle sequencing.

Results

We detected the ER-α A908G mutation in 37 of 653 (5.7%) breast tumors. The absence of this mutation in germline DNA confirmed it to be somatic. Three tumors exhibited only the mutant G base at nucleotide 908 on sequencing, indicating that the wild-type ER-α allele had been lost. The ER-α A908G mutation was found more frequently in higher-grade breast tumors (odds ratio (OR) 2.83; 95% confidence interval (CI) 1.09 to 7.34, grade II compared with grade I), and in mixed lobular/ductal tumors (OR 2.10; 95% CI 0.86 to 5.12) compared with ductal carcinomas, although the latter finding was not statistically significant.

Conclusion

This population-based study, the largest so far to screen for the ER-α A908G mutation in breast cancer, confirms the presence of the mutant in invasive breast tumors. The mutation was associated with higher tumor grade and mixed lobular/ductal breast tumor histology.     

Profil moléculaire du carcinome micropapillaire invasif du sein

Background

Invasive micropapillary carcinoma of the breast is a rare and aggressive histological variant of breast carcinoma. The new molecular classification of breast cancers distinguishing five subtypes, which are characterized by distinct molecular and immunohistochemical features as well as the histological one.

Aims of study

Define the molecular characteristics of invasive micropapillary carcinoma of the breast.

Methods

This is a retrospective review, from 2002 to 2008, included 7 cases of invasive micropapillary carcinoma of the breast diagnosed at the Department of Pathology, Farhat Hached hospital, Sousse, Tunisia. The clinico-pathological features, treatment modalities as well as immunohistochemical features patient??s outcome were recorded.

Results

The mean age of patients was 43.7 years (30?C63 years). Nodular tumefaction was the most common presenting symptom (6 cases) and inflammatory breast in one case. We found visceral metastases (liver) in one case. Five patients underwent surgery, in association with neoadjuvant chemotherapy in 3 cases and adjuvant chemotherapy in 2 cases. These patients underwent post-operative radiotherapy. Tumor size ranged from 10 to 160 millimeters. We found three tumors with histologic grade II, two tumors with grade III and one tumor with grade I. Lymphatic invasion and lymph node metastases were seen respectively in 3 and 4 cases. Estrogen receptors were expressed in 4/7 cases and progesterone receptors were expressed in 5/7 cases. Her 2 was expressed in 2/7 cases, CK5/6 and EGFR were negative in all cases. The Ki-67 was positive in 3 cases. Four cases have a luminal A profile, one case a luminal B profile, one case Her 2 profile and one case ??normal-breast-like?? profile.

Conclusion

Invasive micropapillary carcinoma of the breast is a rare and aggressive histological variant of breast carcinoma which has a heterogeneous molecular profile; further study is required to confirm these constatations.     

Chromodomain helicase DNA binding protein 5 plays a tumor suppressor role in human breast cancer

Introduction

The chromodomain helicase DNA binding protein 5 (CHD5) has recently been identified as a tumor suppressor in a mouse model. The CHD5 locus at 1p36 is deleted, and its mutation has been detected in breast cancer. We, therefore, evaluated whether CHD5 plays a role in human breast cancer.

Methods

We screened mutations in 55 tumors, determined promoter methylation in 39 tumors, measured RNA expression in 90 tumors, analyzed protein expression in 289 tumors, and correlated expression changes with clinicopathological characteristics of breast cancer. Functional effects of CHD5 on cell proliferation, invasion and tumorigenesis were also tested.

Results

Although only one mutation was detected, CHD5 mRNA expression was significantly reduced, accompanied by frequent genomic deletion and promoter methylation, in breast cancer. The extent of methylation was significantly associated with reduced mRNA expression, and demethylating treatment restored CHD5 expression. Lower CHD5 mRNA levels correlated with lymph node metastasis (P = 0.026). CHD5 protein expression was also reduced in breast cancer, and lack of CHD5 expression significantly correlated with higher tumor stage, ER/PR-negativity, HER2 positivity, distant metastasis and worse patient survival (P ≤ 0.01). Functionally, ectopic expression of CHD5 in breast cancer cells inhibited cell proliferation and invasion in vitro and tumorigenesis in nude mice. Consistent with the inhibition of invasion, CHD5 down-regulated mesenchymal markers vimentin, N-cadherin and ZEB1 in breast cancer cells.

Conclusion

Down-regulation of CHD5, mediated at least in part by promoter methylation, contributes to the development and progression of human breast cancer.     

Antitumor effectiveness of different amounts of electrical charge in Ehrlich and fibrosarcoma Sa-37 tumors

Background

Tumor-associated antigens recognized by humoral effectors of the immune system are a very attractive target for human cancer diagnostics and therapy. Recent advances in molecular techniques have led to molecular definition of immunogenic tumor proteins based on their reactivity with autologous patient sera (SEREX).

Methods

Several high complexity phage-displayed cDNA libraries from breast carcinomas, human testis and breast carcinoma cell lines MCF-7, MDA-MB-468 were constructed. The cDNAs were expressed in the libraries as fusion to bacteriophage lambda protein D. Lambda-displayed libraries were efficiently screened with sera from patients with breast cancer.

Results

A panel of 21 clones representing 18 different antigens, including eight proteins of unknown function, was identified. Three of these antigens (T7-1, T11-3 and T11-9) were found to be overexpressed in tumors as compared to normal breast. A serological analysis of the 21 different antigens revealed a strong cancer-related profile for at least five clones (T6-2, T6-7, T7-1, T9-21 and T9-27).

Conclusions

Preliminary results indicate that patient serum reactivity against five of the antigens is associated with tumor disease. The novel T7-1 antigen, which is overexpressed in breast tumors and recognized specifically by breast cancer patient sera, is potentially useful in cancer diagnosis.