Analysis of and prognostic information from disseminated tumour cells in bone marrow in primary breast cancer: a prospective observational study

Background

Disseminated tumour cells (DTCs) in the bone marrow of patients with breast cancer have been identified as an independent predictor of poor prognosis in patients with non-metastatic disease. This prospective study aimed to evaluate the presence and prognostic value of DTCs in the bone marrow of female patients with primary breast cancer.

Methods

Between 1999 and 2003, bone marrow aspirates were obtained from patients at the time of surgery for primary invasive breast cancer. DTCs in bone marrow were identified using monoclonal antibodies against cytokeratins for detection of epithelial cells. The detection of DTCs was related to clinical follow-up with distant disease-free survival (DDFS) and breast cancer-specific survival as endpoints. Bone marrow aspirates from adult healthy bone marrow donors were analysed separately.

Results

DTCs were analysed in 401 patients, and cytokeratin-positive cells were found in 152 of these (38%). An immunofluorescence (IF) staining procedure was used in 327 patients, and immunocytochemistry (IC) was performed in 74 patients. The IF-based method resulted in 40% DTC-positive cases, whereas 30% were positive using IC (p = 0.11). The presence of DTCs in bone marrow was not significantly related to patient or tumour characteristics. The presence of DTCs was not a prognostic factor for DDFS (IF: hazards ratio [HR], 2.2; 95% confidence interval [CI], 0.63–2.2; p = 0.60; IC: HR, 0.84; 95% CI, 0.09–8.1; p = 0.88). Significant prognostic factors were lymph node metastases, oestrogen receptor positivity, Nottingham histological grade, and tumour size using Cox univariate analysis. The analyses were positive for epithelial cells in bone marrow from adult healthy donors in 19 (25%) samples.

Conclusions

The detection of DTCs in bone marrow in primary breast cancer was previously shown to be a predictor of poor prognosis. We were not able to confirm these results in a prospective cohort including unselected patients before the standard procedure was established. Future studies with a standardised patient protocol and improved technique for isolating and detecting DTCs may reveal the clinical applications of DTC detection in patients with micrometastases in the bone marrow.

Abstract PD04-01: Does Analysis of Disseminated Tumor Cells in Bone Marrow Give Additional Prognostic Information in Primary Breast Cancer? Analysis of Disseminated Tumor Cells in Bone Marrow — Report of a Prospective Study with 5 Years Follow-Up

Introduction: Disseminated tumor cells (DTC) in bone marrow of patients with breast cancer has, beyond the formerly known and clinically used prognostic markers, in recent publications been identified as an independent predictor of poor prognosis in patients with non-metastatic disease. Detection of DTC could therefore be a way to identify patients with an increased risk of recurrence among patients with a “good” standard prognostic profile. The present prospective study aimed to evaluate the presence and prognostic value of DTC in bone marrow in women undergoing surgery for primary breast cancer.

Material and methods: From 1999 to 2003 bone marrow aspirates were obtained from the sternal crest in 569 patients during surgery for primary invasive breast cancer. Tumor cells in bone marrow were identified with cytokeratins (4,5,6,7,8,10,13,14,15,16,18,19) against epithelial cells and analyzed with immunofluorescence and immunohistochemistry. The results were related to clinical follow up for 5 years using distant disease free survival (DDFS) and breast cancer specific survival (BCSS) as end-points by uni-and multivariate analysis including standard prognostic factors.

Results: Analysis of DTC were performed in 445 patients and cytokeratin positive cells were found in 159 of these (36%). The presence of DTC in bone marrow was not related to lymph node metastases (N+ 38% vs N-35%, p= 0.4), ER+/ER-(38% vs 30%, p= 0.2) or histological grade (40% grade 1; 37% grade 2; 30% grade 3, p= 0.18). BCSS was related to: lymph node engagement (+ vs -; HR 3.5, p< 0.001), ER (+ vs -; HR 0.55, p= 0.046), histological grade (2 vs 1: HR 4.9, p= 0.03; 3 vs 1: HR 7.4, p= 0.008), age (HR 1.02/year, p= 0.04) and tumor size (>20 mm vs <20 mm: HR 1.8, p= 0.05) in Cox multivariate analysis. Presence of DTC did not correlate either with DDFS (p= 0.97) or BCSS (p= 0.75). In the subgroup N0/ER-, a significantly higher rate of distant metastases was observed in patients with micrometastases in bone marrow (2/12 vs 0/25; p= 0.04; log rank test) and BCSS in the same subgroup was significantly related to the presence of DTC in bone marrow (2/12 vs 0/25; p= 0.04).

Conclusion: Detection of micrometastases in bone marrow in primary breast cancer has previously been shown to be a significant independent predictor of poor prognosis in different studies. In a consecutive cohort including unselected patients we were not able to confirm these results. Our data suggest that it is too early to implement the method of bone marrow aspiration and diagnosis of DTC in clinical routine.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD04-01.

Numb protein expression correlates with a basal-like phenotype and cancer stem cell markers in primary breast cancer

Decreased expression of Numb, resulting in activation of the proto-oncogene Notch1 and reduction in the tumor suppressor p53, has been demonstrated in mammary carcinomas. The aim of this study was to investigate the relationship between Numb protein expression and clinicopathological characteristics, tumor biological subtypes and putative cancer stem cell markers in a well-characterized cohort of primary human breast cancers. Immunohistochemistry was performed on tissue microarrays of primary invasive breast tumors using a polyclonal anti-Numb primary antibody. Of the 241 tumors evaluated, 50 (21%) displayed deficient or reduced Numb immunoreactivity. Retained Numb expression was significantly correlated to estrogen (ER) and progesterone receptor (PR) positivity (P < 0.001 and P = 0.004, respectively). Interestingly, we found that a higher percentage of the tumors with deficient or reduced Numb expression belonged to the triple-negative (ER-/PR-/HER2-) subgroup compared to tumors with retained Numb expression (P = 0.004). Transcriptional profiling of a subset of these tumors linked NOTCH1 and BIRC5, both downstream targets of Numb, to the triple-negative subgroup in an inverse manner. Typically, subgroups characterized by the low expression of Numb expressed higher levels of NOTCH1 and BIRC5 (encoding survivin). We also found deficient expression of Numb in a significantly higher proportion of BRCA1 dependent tumors, which are usually triple-negative, compared to sporadic tumors. The expression of Numb in 14 breast cancer cell lines correlated similarly to their respective molecular subtypes. We further established an inverse correlation between the Numb expression levels and the CD44+/CD24- cancer stem cell phenotype (P = 0.05) in primary tumors. Finally, decreased Numb expression was associated with poorer distant disease-free survival (P = 0.01). Taken together, our results indicate that loss of Numb expression is a marker of tumor aggressiveness, potentially linked to BRCA1 status and a cancer stem cell phenotype in primary breast cancer.

Genomic alterations in histopathologically normal breast tissue from BRCA1 mutation carriers may be caused by BRCA1 haploinsufficiency

Multiple biopsies of normal breast tissue from 10 BRCA1 mutation carriers have been analyzed using array-based comparative genomic hybridization. Normal breast tissue from five age-matched control subjects without a family history of breast cancer was included for reference purposes. We repeatedly found multiple low copy number aberrations at a significantly higher frequency in histopathologically normal tissue from BRCA1 mutation carriers than in normal control tissue. Some of these aberrations were similar across samples from different patients and linked to biological functions such as transcriptional regulation and DNA binding. We also observed a high degree of genomic heterogeneity between samples from the same patient, suggestive of tissue heterogeneity and etiological clonality in the breast epithelium. We show that neither loss of heterozygosity nor promoter methylation of the wild-type BRCA1 allele is the predominant mechanistic origin of the observed genomic instability. Instead, we propose that haploinsufficiency of BRCA1 might be the underlying cause responsible for initiation of breast cancer in these predisposed women, making cells vulnerable to mitotic recombination. We also propose that loss of ERalpha expression is preceded by genetic instability in the initiation of BRCA1-dependent tumorigenesis, indicating that the breast epithelium of BRCA1 mutation carriers may initially be estrogen-responsive. Our results imply that genomic instability instigated by BRCA1 haploinsufficiency may be required for breast cancer initiation in BRCA1 mutation carriers. Finding molecular markers of tumor initiation and progression, for the potential use in early disease detection, may be of great clinical importance for the improved management of at-risk women.

Characterization of a hotspot region on chromosome 12 for amplification in ring chromosomes in atypical lipomatous tumors

Ring chromosomes are cytogenetic hallmarks of genomic amplification in several bone and soft tissue tumors, in particular atypical lipomatous tumors (ALT). In ALT, the ring chromosomes invariably contain amplified material from the central part of the long arm of chromosome 12, mainly 12q12-->15, but often also segments from other chromosomes are involved. Previous studies have shown that one of the recurrent amplicons in ALT, located in 12q13.3-14.1 and harboring the candidate target genes TSPAN31 and CDK4, often has a sharp centromeric border. To characterize this breakpoint region in more detail, 12 cases of ALT with ring chromosomes were analyzed by array comparative genomic hybridization and fluorescence in situ hybridization. In the seven cases showing a sharply delineated amplicon in 12q13.3-14.1, the breakpoint region was further investigated by real time quantitative polymerase chain reaction and Vectorette PCR. The breakpoints clustered to a 146-kb region containing 11 genes. Whereas there was no indication that the breakpoints gave rise to fusion genes, in silico analysis revealed that the breakpoint region was enriched for repeated elements that could be important for ring chromosome formation in ALT.

Comparison of cisplatin sensitivity and the 18F fluoro-2-deoxy 2 glucose uptake with proliferation parameters and gene expression in squamous cell carcinoma cell lines of the head and neck

Background

The survival of patients with locally advanced head and neck cancer is still poor, with 5-year survival rates of 24–35%. The identification of prognostic and predictive markers at the molecular and cellular level could make it possible to find new therapeutic targets and provide "taylor made" treatments. Established cell lines of human squamous cell carcinoma (HNSCC) are valuable models for identifying such markers.

The aim of this study was to establish and characterize a series of cell lines and to compare the cisplatin sensitivity and 18F fluoro-2 deoxy 2 glucose (18F-FDG) uptake of these cell lines with other cellular characteristics, such as proliferation parameters and TP53 and CCND1 status.

Methods

Explant cultures of fresh tumour tissue were cultivated, and six new permanent cell lines were established from 18 HNSCC cases. Successfully grown cell lines were analysed regarding clinical parameters, histological grade, karyotype, DNA ploidy, and index and S-phase fraction (Spf). The cell lines were further characterized with regard to their uptake of 18F-FDG, their sensitivity to cisplatin, as measured by a viability test (crystal violet), and their TP53 and CCND1 status, by fluorescence in situ hybridization (FISH), polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) with DNA sequencing and, for cyclin D1, by immunohistochemistry.

Results

Patients with tumours that could be cultured in vitro had shorter disease-free periods and overall survival time than those whose tumours did not grow in vitro, when analysed with the Kaplan-Meier method and the log-rank test. Their tumours also showed more complex karyotypes than tumours from which cell lines could not be established. No correlation was found between TP53 or CCND1 status and 18F-FDG uptake or cisplatin sensitivity. However, there was an inverse correlation between tumour cell doubling time and 18F-FDG uptake.

Conclusion

In vitro growth of HNSCC cells seem to be an independent prognostic factor, with cell lines being more readily established from aggressive tumours, a phenomenon more dependent on the molecular genetic characteristics of the tumour cells than on tumour location or TNM status.

Cytogenetic characterization and gene expression profiling of the trastuzumab-resistant breast cancer cell line JIMT-1

Resistance to the HER-2 targeting drug trastuzumab can be observed clinically, but the lack of suitable experimental models hampers studies of resistance mechanisms. We characterized a HER-2-positive carcinoma cell line (JIMT-1) derived from a 62-year-old breast cancer patient which was clinically resistant to trastuzumab. Multicolor fluorescence in situ hybridization revealed a complex hyperdiploid karyotype with numerous marker chromosomes and unbalanced translocations. Comparative genomic hybridization (CGH) revealed numerous regions of copy number aberration (CNA). Further analysis by array CGH identified 27 regions of CNA (16 amplified, 11 deleted). Thirty-eight percent of the genes in the amplified regions were overexpressed, compared to only 9% in regions of normal copy number ratios (CNR). Accordingly, 26% of the genes in the deleted regions were underexpressed, compared to 10% in regions of normal CNR. Most amplified and overexpressed genes were located on chromosome 1 as well as on 8q, 12q14.1, 17q11 approximately q21, and 20q13. In 17q11 approximately q21, we identified two separate amplicons, the HER-2 amplicon and a previously unreported amplicon at 17q21.31. Several aberrant genes are implicated in cancer development (e.g., JUN, CDK4, and SLUG protooncogenes, as well as the drug/hormone-metabolizing genes GSTM1 and CYP24). We conclude that cytogenetic and expression profiling of JIMT-1 revealed several new features that need further characterization and may shed light on trastuzumab resistance.

High-throughput genomic technology in research and clinical management of breast cancer. Molecular signatures of progression from benign epithelium to metastatic breast cancer

It is generally accepted that early detection of breast cancer has great impact on patient survival, emphasizing the importance of early diagnosis. In a widely recognized model of breast cancer development, tumor cells progress through chronological and well defined stages. However, the molecular basis of disease progression in breast cancer remains poorly understood. High-throughput molecular profiling techniques are excellent tools for the study of complex molecular alterations. By accurately mapping changes in the genome and subsequent biological/molecular pathways, the chances of finding potential novel treatment targets as well as intervention strategies are enhanced, and ultimately lives can be saved. This review provides a brief summary of recent progress in identifying molecular markers for invasiveness in early breast lesions.

Amplification of the cyclin D1 gene is associated with tumour subsite, DNA non-diploidy and high S-phase fraction in squamous cell carcinoma of the head and neck

Amplification of CCND1 (cyclin D1 gene) in squamous cell carcinoma of the head and neck (SCCHN) is correlated to poor prognosis. The purpose of this study was to investigate whether CCND1 amplification is related to different subsites and also to DNA ploidy status and S-phase fraction (SPF). Biopsies from 67 patients with SCCHN were analysed for CCND1 amplification by fluorescence in situ hybridisation (FISH) and for ploidy status and SPF by flow cytometry (FCM). Twenty-one of 67 tumours (31%) showed CCND1 amplification and the frequencies differed significantly between different subsites (p = 0.01). Tumours from hypopharynx, larynx and oropharynx showed higher rates of amplification as compared to tumours from oral cavity and epipharynx. CCND1 amplification was also associated to DNA non-diploidy and high SPF (p = 0.002 and p = 0.002, respectively). In conclusion, the rate of CCND1 amplification differed between different subsites in SCCHN and was also associated to a more aggressive tumour phenotype, as defined by DNA non-diploidy and high SPF.

Patterns of chromosomal imbalances defines subgroups of breast cancer with distinct clinical features and prognosis. A study of 305 tumors by comparative genomic hybridization

Chromosomal copy number aberrations (CNAs) are common in breast cancer and involve genomic regions in a frequency and combination, suggesting distinct routes of tumor development. We studied chromosomal gains (+) and losses (-) by comparative genomic hybridization from a series of 305 unselected primary invasive breast cancers. CNAs were observed in >90% of the tumors and involved all chromosomal arms in various frequencies, the most common being +1q (55%), +8q (41%), +16p (40%), +17q (28%), -13q (27%), -16q (22%), +20q (19%), -8p (18%), and +11q (16%). Eighteen pairs of CNAs were revealed as significantly associated using Fisher's exact test with Bonferroni correction, the most common pairs being -8p/+8q, +17q/+20q, and -4q/-13q. To study more complex relationships between individual CNAs, principal component analysis and distance-based tree modeling were performed independently. Three distinct patterns of CNAs were observed. Group A was defined by +1q, +16p, and -16q, group B by +11q, +20q, +17q, and -13q, and group C by -8p and +8q. Group A was correlated to positive estrogen receptor and progesterone receptor (PgR) status (P < 0.001 and P < 0.05, respectively). Groups B and C were correlated to DNA nondiploidy (P < 0.001 and P < 0.05), high histological grade and lymph node positivity (P < 0.05), and group B also to high proliferation rate, large primary tumor size (P < 0.001), and negative PgR status (P < 0.05). Patients with aberrations in group A only had a significantly higher breast cancer survival rate than all other patients. The worst survival was seen for patients with aberrations in group C only along with the patients displaying aberrations from all CNA pattern groups (ABC). The 5-year survival rates vary from 96% in group A to 56% in group C. These correlations were independent of node status, tumor size, and PgR status in a multivariate analysis. We conclude that patterns of copy number gains and losses define breast tumors with distinct clinicopathological features and patient prognosis.

Characterization of a novel breast carcinoma xenograft and cell line derived from a BRCA1 germ-line mutation carrier

A human tumor xenograft (L56Br-X1) was established from a breast cancer axillary lymph node metastasis of a 53-year-old woman with a BRCA1 germ-line nonsense mutation (1806C>T; Q563X), and a cell line (L56Br-C1) was subsequently derived from the xenograft. The xenograft carries only the mutant BRCA1 allele and expresses mutant BRCA1 mRNA but no BRCA1 protein as determined by immunoprecipitation or Western blotting. The primary tumor, lymph node metastasis, and xenograft were hypodiploid by DNA flow cytometry, whereas the cell line displayed an aneuploidy apparently developed via polyploidization. Cytogenetic analysis, spectral karyotyping, and comparative genomic hybridization of the cell line revealed a highly complex karyotype with numerous unbalanced translocations. The xenograft and cell line had retained a somatic TP53 missense mutation (S215I) originating from the primary tumors, as well as a lack of immunohistochemically detectable expression of steroid hormone receptors, epidermal growth factor receptor, human epidermal growth factor receptor 2 (HER-2), and keratin 8. Global gene expression analysis by cDNA microarrays supported a correlation between the expression profiles of the primary tumor, lymph node metastasis, xenograft, and cell line. We conclude that L56Br-X1 and L56Br-C1 are useful model systems for studies of the pathogenesis and new therapeutic modalities of BRCA1-induced human breast cancer.

Chromosomal rearrangements and oncogene amplification precede aneuploidization in the genetic evolution of breast cancer

Breast carcinoma is thought to arise because of multiple successive changes in the genome of the normal epithelial cells. However, little is known of the order of appearance of different types of genetic aberrations We studied the ERBB2 (Her-2/neu) and CCND1 (cyclin D1) oncogene amplification in flow cytometrically sorted diploid and nondiploid tumor cell populations by fluorescence in situ hybridization (FISH). The purity of the cell sorting was confirmed by static DNA image cytometry. Spectral karyotyping was used to define differences in a genome-wide manner between two distinctly different aneuploid cell clones found in each of two breast cancer cell lines. FISH indicated the presence of gene amplification both in diploid and nondiploid cell clones in 17 of the 21 amplification-containing tumors analyzed. The oncogene copy numbers remained unchanged throughout aneuploidization in 11 of 17 tumors. The remaining six tumors showed an increase in oncogene copy number as well as the number of chromosome 11 or 17 centromeres (the original location of CCNDI and ERBB2, respectively). Breast carcinoma cell lines MDA-157 and MDA-436 showed a significant number of chromosomal rearrangements in the near-diploid clones, which were present in duplicate in the corresponding aneuploid (polyploid) clones. These results indicate that ploidy shift, ie., aneuploidization, in breast cancer is a late genetic event which is preceded by both oncogene amplifications as well as many chromosomal rearrangements.