Single cell analysis techniques have great potential in the cancer genomics field. The detection and characterization of circulating tumour cells are important for identifying metastatic disease at an early stage and monitoring it. This protocol is based on transcript profiling using Reverse Transcriptase Multiplex Ligation-dependent Probe Amplification (RT-MLPA), which is a specific method for simultaneous detection of multiple mRNA transcripts. Because of the small amount of (circulating) tumour cells, a pre-amplification reaction is performed after reverse transcription to generate a sufficient number of target molecules for the MLPA reaction. We designed a highly sensitive method for detecting and quantifying a panel of seven genes whose expression patterns are associated with breast cancer, and optimized the method for single cell analysis. For detection we used a fluorescence-dependent semi-quantitative method involving hybridization of unique barcodes to an array. We evaluated the method using three human breast cancer cell lines and identified specific gene expression profiles for each line. Furthermore, we applied the method to single cells and confirmed the heterogeneity of a cell population. Successful gene detection from cancer cells in human blood from metastatic breast cancer patients supports the use of RT-MLPA as a diagnostic tool for cancer genomics.

The ATM-p53 DNA-damage response (DDR) pathway has a crucial role in chemoresistance in CLL, as indicated by the adverse prognostic impact of genetic aberrations of TP53 and ATM. Identifying and distinguishing TP53 and ATM functional defects has become relevant as epigenetic and posttranscriptional dysregulation of the ATM/p53 axis is increasingly being recognized as the underlying cause of chemoresistance. Also, specific treatments sensitizing TP53- or ATM-deficient CLL cells are emerging. We therefore developed a new ATM-p53 functional assay with the aim to (i) identify and (ii) distinguish abnormalities of TP53 versus ATM and (iii) enable the identification of additional defects in the ATM-p53 pathway. Reversed transcriptase multiplex ligation-dependent probe amplification (RT-MLPA) was used to measure ATM and/or p53-dependent genes at the RNA level following DNA damage using irradiation. Here, we showed that this assay is able to identify and distinguish three subgroups of CLL tumors (i.e., TP53-defective, ATM-defective and WT) and is also able to detect additional samples with a defective DDR, without molecular aberrations in TP53 and/or ATM. These findings make the ATM-p53 RT-MLPA functional assay a promising prognostic tool for predicting treatment responses in CLL.

BACKGROUNDWe have previously reported an array comparative genomic hybridization profile that identifies triple-negative breast cancers (TNBC), with BRCA1 dysfunction and a high sensitivity to intensified dose bifunctional alkylating agents. To determine the effect of conventional-dose chemotherapy in patients with this so-called BRCA1-like profile, clinical characteristics and survival were studied in a large group of TNBC patients.PATIENTS AND METHODSDNA was isolated and BRCA1-like status was assessed in 101 patients with early-stage TNBC receiving adjuvant cyclophosphamide-based chemotherapy. Clinical characteristics and survival were compared between BRCA1-like and non-BRCA1-like groups. Results Sixty-six tumors (65%) had a BRCA1-like profile. Patients with BRCA1-like tumors tended to be younger and had more often node-negative disease (P = 0.06 and P = 0.03, respectively). Five-year recurrence-free survival was 80% for the BRCA1-like group and 75% for the non-BRCA1-like group (P = 0.35). T stage was the only variable significantly associated with survival.CONCLUSIONSBRCA1-like tumors share clinical features, like young age at diagnosis and similar nodal status, with breast cancers in BRCA1 mutation carriers. Their prognosis is similar to that of non-BRCA1-like tumors when conventional-dose chemotherapy is administered. TNBCs that are classified as BRCA1-like may contain a defect in homologous recombination and could, in theory, benefit from the addition of poly ADP ribose polymerase inhibitors.

Abstract Background Our group has previously employed array Comparative Genomic Hybridization (aCGH) to assess the genomic patterns of BRCA1-mutated breast cancers. It is reasonable to assume that this pattern indicates ‘BRCAness’ and thus serves as a marker for homologous recombination deficiency. This BRCA1-like aCGH profile is also present in about half of all triple negative sporadic breast cancers and has been shown to be predictive for benefit from intensive chemotherapy with DNA crosslinking agents. To study BRCA1-like tumors and conventional dose chemotherapy sensitivity in more detail, we compared clinical factors and survival rates in a uniform cohort of triple negative breast tumors treated with alkylating agents. Patients and methods 103 patients with triple negative tumors received conventional dose adjuvant chemotherapy with doxorubicin/cyclophosphamide. DNA was extracted from tumor samples and BRCA1-like profiles were assessed. Tumors were classified as BRCA1 -like or non-BRCA1-like. Standard clinical and histopathological factors were determined and compared between both groups. Relapse free survival (RFS), disease specific survival (DSS) and overall survival (OS) after diagnosis were compared between BRCA1-like and non-BRCA1-like tumors. Results 66 tumors (65%) had a BRCA1-like profile, while 35 tumors (35%) did not show such a profile. Patients with BRCA1-like tumors tended to be younger and had more often node-negative disease compared to the patients with non-BRCA1-like tumors (p=0.058 and p=0.034, respectively). There was no significant difference in survival between BRCA1-like and non BRCA1-like patients after treatment with alkylating agents: the median RFS was 121 vs. 109 months, median DSS was 129 vs. 114 months and OS was 127 vs. 110 months, for BRCA1-like versus non-BRCA1-like tumors. T-stage was the only variable significantly associated with survival. Conclusion BRCA1-like tumors occurred in younger patients and were more often node negative, which are features shared with tumors in BRCA1-mutation carriers. We did not observe a difference in survival between BRCA1-like and non-BRCA1-like triple negative breast cancers after treatment with conventional dose chemotherapy with alkylating agents. These results confirm our previous findings that BRCA1-like tumors have similar sensitivity to anthracycline-based adjuvant chemotherapy as other triple-negative tumors. It will be important to establish whether BRCA1-like tumors also share the exquisite sensitivity of BRCA-mutated tumors to PARP-inhibitors. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD03-08.

BackgroundTumors with homologous recombination deficiency (HRD), such as BRCA1-associated breast cancers, are not able to reliably repair DNA double-strand breaks (DSBs) and are therefore highly sensitive to both DSB-inducing chemotherapy and poly (ADP-ribose) polymerase inhibitors. We have studied markers that may indicate the presence of HRD in HER2-negative breast cancers and related them to neoadjuvant chemotherapy response.Patients and methodsArray comparative genomic hybridization (aCGH), BRCA1 promoter methylation, BRCA1 messenger RNA (mRNA) expression and EMSY amplification were assessed in 163 HER2-negative pretreatment biopsies from patients scheduled for neoadjuvant chemotherapy.ResultsFeatures of BRCA1 dysfunction were frequent in triple-negative (TN) tumors: a BRCA1-like aCGH pattern, promoter methylation and reduced mRNA expression were observed in, respectively, 57%, 25% and 36% of the TN tumors. In ER+ tumors, a BRCA2-like aCGH pattern and the amplification of the BRCA2 inhibiting gene EMSY were frequently observed (43% and 13%, respectively) and this BRCA2-like profile was associated with a better response to neoadjuvant chemotherapy.ConclusionsAbnormalities associated with BRCA1 inactivation are present in about half of the TN breast cancers but were not predictive of chemotherapy response. In ER+/HER2- tumors, a BRCA2-like aCGH pattern was predictive of chemotherapy response. These findings should be confirmed in independent series.