Biophenotypes and survival of BRCA1 and TP53 deleted breast cancer in young women

Characterization of the HER2 status in BRCA-mutated breast cancer: a single institutional series and systematic review with pooled analysis

BACKGROUND

Pathogenic variants (PVs) in BRCA1/2 genes account for ∼6% of breast and 20% of ovarian cancers. Most breast tumors developed by BRCA1 carriers are triple negative. BRCA2 tumors have similar rates of estrogen receptor positivity as sporadic controls but are less likely to be human epidermal growth factor receptor 2 (HER2)-positive. Prevalence of HER2 positivity among breast cancers (BCs) in BRCA1/2 mutation carriers is poorly and variably described, ranging from 0% to 10% and 0% to 13% in BRCA1 and BRCA2 carriers, respectively.

PATIENTS AND METHODS

We assessed the prevalence of HER2 positivity among a single institutional cohort of 398 BCs developed in carriers of BRCA1/2 PVs (240 BRCA1, 158 BRCA2). Subsequently, a systematic review of the literature and pooled analysis was carried out.

RESULTS

In our series we found a 7% HER2 positivity rate among all first BRCA1/2 BCs overall. In BRCA1 carriers, 5.4% of BCs were HER2-positive compared with 9.5% in BRCA2-mutated patients. Among bilateral BCs, HER2-positive cases were 15.2% in the BRCA1 group and 23.1% in the BRCA2 group. Notably, six BRCA1 and eight BRCA2 carriers showed discordant HER2 status between BC and bilateral BC (23.7%, 14/59). The systematic review included 21 083 BRCA1/2 patients from 73 eligible studies. The pooled rate of BRCAmut/HER2-positive BCs is 9.1% (95% confidence interval 7.3% to 11.2%). BRCA1 and BRCA2 when reported as separate data ranged from 0% to 33.3% (mean 8.3%) and from 0% to 86% (mean 10.3%), respectively.

CONCLUSIONS

As compared with sporadic cases, BCs occurring in BRCA1 and/or BRCA2 PVs carriers are less frequently HER2-positive. Prevalence of HER2 positivity in our series was consistent with pooled analysis and did not exceed 10%. Although not common, co-existence of BRCA mutations and HER2 overexpression and/or gene amplification should be acknowledged. More research is needed to better characterize this subgroup of patients who should not be excluded a priori from clinical trials of targeted therapy for BRCA1/2-driven cancers.

Spinophilin loss correlates with poor patient prognosis in advanced stages of colon carcinoma

PURPOSE

The genomic region 17q21 is frequently associated with microsatellite instability and LOH in cancer, including gastric and colorectal carcinomas. This region contains several putative tumor suppressor genes, including Brca1, NM23, prohibitin, and spinophilin (Spn, PPP1R9B, neurabin II). The scaffold protein Spn is one of the regulatory subunits of phosphatase-1 (PP1) that targets PP1 to distinct subcellular locations and couples PP1 to its target. Thus, Spn may alter cell-cycle progression via the regulation of the phosphorylation status of the retinoblastoma protein, a direct target of PP1. Therefore, we analyzed whether Spn levels were reduced in colorectal carcinomas and whether Spn levels correlated with prognosis or response to therapy.

EXPERIMENTAL DESIGN

By means of immunohistochemistry or quantitative PCR, we studied the levels of Spn in stages II, III, and IV colorectal carcinoma tumors and correlated to other clinicopathologic features as well as prognosis or response to therapy.

RESULTS

Spn was lost in a percentage of human gastric, small intestine, and colorectal carcinomas. In patients with colorectal carcinoma, tumoral Spn downregulation correlated with a more aggressive histologic phenotype (poorer tumor differentiation and higher proliferative Ki67 index). Consistent with this observation, lower Spn protein expression levels were associated with faster relapse and poorer survival in patients with stage III colorectal carcinoma, particularly among those receiving adjuvant fluoropyrimidine therapy. We validated this result in an independent cohort of patients with metastatic colorectal carcinoma treated with standard chemotherapy. Although patients that achieved an objective tumor response exhibited Spn levels similar to nontumoral tissue, nonresponding patients showed a significant reduction in Spn mRNA levels.

CONCLUSIONS

Our data suggest that Spn downregulation contributes to a more aggressive biologic behavior, induces chemoresistance, and is associated with a poorer survival in patients with advanced stages of colorectal carcinoma.

Loss of heterozygosity at BRCA1 locus is significantly associated with aggressiveness and poor prognosis in breast cancer

BACKGROUND

BRCA1 and BRCA2 are two major tumor suppressor genes for hereditary breast and ovarian cancer. In sporadic breast cancer, although somatic mutations of these genes are rare, loss of heterozygosity (LOH) at BRCA1 and BRCA2 loci is common.

METHODS

LOH at BRCA1 and BRCA2 loci were investigated in 202 Japanese invasive breast cancer patients. The relationships between LOH at these gene loci and clinicopathologic characteristics were analyzed.

RESULTS

Among 166 informative cases for both BRCA1 and BRCA2 loci, 69 (41.6%) and 52 (31.3%) tumors revealed LOH at BRCA1 and BRCA2 loci, respectively. LOH at BRCA1 LOH or BRCA2 locus was associated with higher nuclear grade (P < 0.0001, P = 0.0187). LOH at BRCA1 locus was associated with estrogen receptor and progesterone receptor negativity (P = 0.001 and P = 0.015) and significantly shorter disease-free survival (P < 0.0001), distant metastasis-free survival (P < 0.0001), and overall survival (P < 0.0001). In contrast, LOH at BRCA2 locus had no associations with estrogen receptor or progesterone receptor status and prognosis. LOH at BRCA1 locus was independently associated with poor prognosis in terms of disease-free survival (hazard ratio 3.08, 95% confidence interval [CI] 1.58-6.18, P = 0.0009), distant metastasis-free survival (hazard ratio 5.18, 95% CI 2.35-12.19, P < 0.0001), and overall survival (hazard ratio 4.97, 95% CI 1.84-15.1, P = 0.0013).

CONCLUSIONS

LOH at BRCA1 locus could be an independent prognostic biomarker useful in identifying a subgroup of patients with poor prognosis.

Clinical implication of p53 overexpression in breast cancer patients younger than 50 years with a triple-negative subtype who undergo a modified radical mastectomy

OBJECTIVE

The purpose of this study was to identify the clinicopathological characteristics and prognostic value of p53 overexpression in breast cancer patients treated with a modified radical mastectomy.

METHODS

The medical records of 197 patients who had undergone modified radical mastectomy between January 1991 and December 2008 were reviewed retrospectively. Breast cancer subtype and p53 overexpression were investigated using immunohistochemistry and/or fluorescent in situ hybridization analysis of surgical specimens.

RESULTS

The median follow-up after the modified radical mastectomy was 56.1 months (range, 14.7-232.7). The median age was 47 years (range, 31-72). p53 overexpression was noted in 73 patients (37.1%). Breast cancer-specific death rate (P = 0.011), cancer progression (P = 0.024), distant metastasis (P = 0.015), hormone receptor negativity (P < 0.001) and human epidermal growth factor receptor 2 positivity (P = 0.017) were detected more frequently in patients with p53 overexpression. The overall survival rates were significantly lower in the p53-overexpression group than in the non-p53-overexpression group (P = 0.021, log-rank test). In the multivariate analysis, p53 overexpression showed the strongest prognostic significance in patients aged <50 years (P = 0.039) and with the triple-negative subtype (P = 0.023).

CONCLUSIONS

p53 overexpression correlated with breast cancer-specific death rates and adverse prognostic factors in patients treated with modified radical mastectomy. p53 overexpression might be a more reliable prognosticator in patients aged <50 years and with the triple-negative subtype. More effective systemic treatments might be warranted for these patients exhibiting p53 overexpression. Further validation is required to make more definite conclusions.

Down-regulation of spinophilin in lung tumours contributes to tumourigenesis

The scaffold protein spinophilin (Spn, PPP1R9B) is one of the regulatory subunits of phosphatase-1a (PP1), targeting it to distinct subcellular locations and to its target. Loss of Spn reduces PPP1CA levels, thereby maintaining higher levels of phosphorylated pRb. This effect contributes to an increase in p53 activity. However, in the absence of p53, reduced levels of Spn increase the tumourigenic properties of cells. In addition, Spn knockout mice have a reduced lifespan, an increased number of tumours and increased cellular proliferation in some tissues, such as the mammary ducts. In addition, the combined loss of Spn and p53 activity leads to an increase in mammary carcinomas, confirming the functional relationship between p53 and Spn. In this paper, we report that Spn is absent in 20% and reduced in another 37% of human lung tumours. Spn reduction correlates with malignant grade. Furthermore, the loss of Spn also correlates with p53 mutations. Analysis of miRNAs in a series of lung tumours showed that miRNA106a* targeting Spn is over-expressed in some patients, correlating with decreased Spn levels. Proof-of-concept experiments over-expressing miRNA106a* or Spn shRNA in lung tumour cells showed increased tumourigenicity. In conclusion, our data showed that miRNA106a* over-expression found in lung tumours might contribute to tumourigenesis through Spn down-regulation in the absence of p53.

Differential association of BRCA1 and BRCA2 genes with some breast cancer-associated genes in early and late onset breast tumors

BACKGROUND

Accumulating evidence indicating more aggressive features of breast carcinoma (BC) in young women than their older counterparts have raised the question of whether these differences are present at the genetic level.

METHODS

For this purpose, we performed a comparative analysis of the frequency of deletions of BRCA1, BRCA2, BRCAX, TP53, ATM, and RB1 and amplification of Cyclin D1 and also studied the interrelation and prognostic significance of these genetic alterations in 30 early onset (< or =40 years) and 33 late onset (>40 years) cases of BC. These gene alterations were also studied in 11 other types of breast lesions.

RESULTS

A differential pattern of alterations (deletion/amplification) was observed in the two age groups, with the sequence in younger women being BRCA1 (72%), TP53 (71%), ATM (64%), BRCA2 (62%), RB1 (60%), Cyclin D1 (43%), and BRCAX (24%) and that in the older group being TP53 (66%), RB1 (63%), BRCA1 (56%), ATM (53%), BRCA2 (45%), Cyclin D1 (24%), and BRCAX (23%). Similar, differential correlations were also seen with several clinicopathological parameters, prognosis, and combinations of alterations among these genes in the two age groups.

CONCLUSIONS

Differential frequencies and interrelationships of genetic alterations and prognoses in these two age groups indicate that the molecular pathways for the development of tumors in both age groups may not be similar, though the ultimate effect is deregulation of cell cycle checkpoints and defects in the DNA repair pathway.

Loss of heterozygosity of the BRCA1 and FHIT genes in patients with sporadic breast cancer from Southern Brazil

AIM

The evaluation of allelic losses at the FHIT and the BRCA1 genes and at three other loci at the 17q region in a series of 34 sporadic breast cancer cases from Southern Brazil.

METHODS

The samples were evaluated for loss of heterozygosity (LOH) at the FHIT and the BRCA1 genes and at three other microsatellite markers at 17q, and the findings were correlated with clinicopathological parameters.

RESULTS

The BRCA1 intragenic marker, D17S855, had the highest frequency of LOH, detected in 10 of 24 informative cases, followed by the D17S579 (six of 23 informative cases), D17S806 (five of 21 informative cases), and D17S785 markers (five of 21 informative cases). LOH at the FHIT intragenic marker, D3S1300, was found in six of 25 informative cases. In four of the six cases with LOH of the FHIT gene, there was concomitant loss of the BRCA1 intragenic marker.

CONCLUSIONS

The frequency of allelic losses in the FHIT and BRCA1 loci in the Southern Brazilian population is similar to that described in the general population. No correlations were found when the total LOH frequency was compared with tumour size, grade, or presence of axillary lymph node metastasis. Further studies using larger sporadic breast cancer samples and additional markers would be useful to confirm these findings, in addition to establishing more specific associations with clinicopathological parameters in this specific population.

FISH analysis of BRCA1 copy number in paraffin-embedded ovarian cancer tissue samples

We investigated the BRCA1 gene copy number in unselected ovarian malignancies. Both additional genes (amplification) as well as deletion (loss of heterozygosity, LOH) are often thought to have a role in the initiation or progression of cancer. In addition, if there were little change, deletion studies might help identify BRCA1 mutation carriers. Forty-seven paraffin-embedded ovarian tissue blocks obtained between 1984 and 1997 were used for this study. A sample was "deletion-positive" when BRCA1-deleted cells in the tumor area were significantly different from the benign area. Twenty-five (53%) cases were found to be "deletion-positive". The average age of onset of "deletion-positive" patients was 50.8 years and of "deletion-negative" 57.8 years (P < 0.05). There was no statistical difference between groups in the staging, histology, or prognosis. A Kaplan-Meier study did show a trend towards poorer survival for "deletion-positive" patients. FISH permits unique molecular characterization of malignancies at a cellular level. Double amplification of HER-2 and c-myc predicts poor ovarian cancer survival. There appears to be a definite role for BRCA1 deletion in reducing the age of ovarian cancer onset and possibly in overall survival. Further FISH studies of this and other patient sets using additional molecular markers are needed.

Breast cancer in young women: clinicopathological features and biological specificity

Literature data suggest that breast cancers occurring in young patients may be different from those arising in older women. In this study the clinicopathologic characteristics of 50 patients under 40 years of age were compared with those of patients aged over 60. Patients under 40 years old more frequently had a family history of breast cancer than did older patients (24% vs 17%) and had more often used oral contraceptives (29% vs 13%); on average they had experienced menarche 1 year earlier. For early onset breast carcinomas there was a higher frequency of grade 3 tumours (38% vs 17%) and oestrogen receptor negativity (46% vs 20%). In addition, in younger patients the carcinomas were mostly DNA aneuploid (78% vs 58%), with a higher proliferation rate (48% vs 26%) and more frequent c-erbB-2 overexpression (48% vs 26%) and p53 alteration (30% vs 8%). Our data demonstrate that breast cancers arising in young women have a significantly different biopathological profile from those in older patients, with a predominance of unfavourable prognostic parameters.

DNA repair and breast carcinoma susceptibility in women

BACKGROUND

Breast carcinoma is the most common cancer and the second leading cause of cancer-related deaths among women. The disease represents approximately 31% of all cancers in Puerto Rican women. Several DNA repair pathways are involved in preventing carcinogenesis. The current study evaluated the hypothesis that a reduced DNA repair capacity (DRC) is a susceptibility factor for breast carcinoma.

METHODS

A retrospective case-control clinical study was performed to compare age-matched DRC in 33 women with histopathologically confirmed breast carcinoma (cases) and 47 cancer-free women (controls). DRC was measured using a host cell reactivation assay with a luciferase reporter gene and then transfected into human peripheral lymphocytes. A questionnaire was used to solicit breast carcinoma risk factors.

RESULTS

Women with breast carcinoma had a mean DRC of 5.6% +/- 0.5 standard error of the mean (SEM). Cancer cases had a 36% reduction (P<0.001) in DRC when compared with the control group (DRC=8.7% +/- 0.7 SEM). Younger participants with breast carcinoma were found to have a more significant reduction in DRC when compared with age-matched controls. Family (odds ratio [OR]=4.1), maternal lineage (OR=5.5), and maternal (OR=12.4) history of breast carcinoma were found to be the only statistically significant (P<0.05) risk factors associated with the disease.

CONCLUSIONS

The findings supported the hypothesis that a low DRC is a susceptibility factor for breast carcinoma. A 1% decrease in DRC corresponded to a 22% increase in breast carcinoma risk. To the authors' knowledge, the current study was the first to directly determine the DRC of women with breast carcinoma. Because DRC is an independent risk factor for breast carcinoma, the DRC of women may be a useful marker in predicting susceptibility.

Breast cancer in young women (?35 years): Genomic aberrations detected by comparative genomic hybridization

Sporadic breast cancer in young women is different from the one in older patients regarding pathological features and aggressiveness of the tumors, but the spectrum of genetic alterations are largely unknown. We used comparative genomic hybridization (CGH) to analyze DNA copy number changes in 88 tumor samples from women </=35 years of age. Findings were compared to histopathological data including tumor type, grading, lymph nodes and metastasis. Genomic gains clustered to chromosome arms 1q (64.8%), 8q (61.4%), 17q (50.0%), 20q (33.0%), 3q (20.5%), 1p (17.0%), 5p (17.0%) and 15q (17%). Losses were commonly located on 8p (19.3 %), 11q (11.4%), 16q (11.4%), 17p (11.4%) and 18q (10.2%). A comparison with published CGH data from breast carcinomas of similar type and grade showed the following differences: (1) gains were much more frequent than losses, and (2) losses on 8p22-p23 were more prevalent in patients with positive lymph node metastasis (p = 0.02), and Grade III tumors were associated with gains on the long arm of chromosome 8 (p = 0.01). Therefore, alterations in these genomic regions may be responsible for the reduced survival of patients with early onset breast cancer.

Molecular cytogenetic investigations of synchronous bilateral breast cancer

BACKGROUND

Bilaterality in breast cancer is a rare event and together with an early onset of disease points towards inheritance of the disease. However, most cases seem to occur sporadically, either in a synchronous or metachronous manner.

METHODS

Thirty two invasive carcinomas and one in situ carcinoma from 16 patients with synchronous, bilateral breast cancer were investigated by means of comparative genomic hybridisation (CGH) and polymerase chain reaction based multiplex microsatellite analysis. The results were analysed conventionally and were also subjected to a biomathematical cluster analysis.

RESULTS

On average, bilateral breast cancer cases showed a low number of genetic alterations, a low frequency of genetic amplifications, and a high rate of chromosomal 16q losses. A distinct, characteristic genetic alteration associated with bilateral breast disease could not be found. Although two tumour pairs appeared to be related using biomathematical processing for microsatellite analysis, this result was reproduced by CGH data processing in one patient only.

CONCLUSIONS

Most synchronous, bilateral breast cancer cases seem to represent independent tumours rather than metastatic events. Nevertheless, the possibility of a specific susceptibility remains.

Allelic loss in breast cancer

Breast cancer is the most prevalent cancer type in women and allelic loss constitutes one of the commonest genetic alterations in mammary neoplasias. Frequent detection of Loss of Heterozygosity indicates genes with putative tumour suppressor activity in breast carcinomas. Imbalance between two alleles might also be related with increased expression of an oncogene within a locus. Loci exhibiting frequent allelic loss in breast cancer have been detected, spread throughout the genome, and may contain genes with potential significance in breast carcinogenesis. Loss of Heterozygosity patterns in breast cancer give evidence for multiple clonality of the disease, and that accumulation of such lesions is probably implicated in disease development. Studies on deletions of known breast cancer genes suggest interactions with other common genetic events during disease initiation and progression. Allelic loss has been repeatedly associated with adverse characteristics and poor outcome in breast neoplasms. Detection of allelic loss in the serum of breast cancer patients and in premalignant breast lesions could herald the potential for diagnosis of the disease at an early, and thus curable, stage.

Genetic and cytogenetic analyses of breast cancer yield different perspectives of a complex disease

Genomic instability in breast cancer results in low-level changes in DNA copy number, a significant but poorly understood mechanism underlying the genetic heterogeneity of this disorder. Two different approaches, loss of heterozygosity (LOH) and comparative genomic hybridization (CGH), have been used to probe the genetics of breast cancer evolution. LOH is a locus specific method that detects the variation in the parental origin of DNA, but is not quantitative. CGH provides a genome-wide accounting of the magnitude of DNA copy number changes, but not parental origin. Both methods have identified complex and heterogeneous patterns of DNA losses, duplications, and amplifications during breast cancer evolution. LOH and CGH technologies interrogate very distinct mechanisms driving breast tumor evolution, yet are seldom used in parallel to profile specimens. Thus, the relative significance of genetic versus numerical variations of DNA in breast cancer evolution remains undefined. This review will attempt to summarize some of the successes of these investigations, highlight some complex and confounding observations emerging from these studies, and discuss the potential of these studies to improve our understanding of breast cancer biology and treatment.