Molecular characterization of breast cancer cell lines by a low-density microarray.

We designed a low-density microarray carrying 132 DNA capture sequences highly specific for genes known to be differentially expressed among breast tumors and BCC lines or associated with specific tumor properties (cell-cycle alteration, proteolysis, adhesion, hormone sensitivity, etc). We analyzed gene expression in 11 BCC lines among which 6 had already been extensively studied (BT-474, Hs578T, MCF-7, MDA-MB-231, MDA-MB-453, T-47D) and 5 were still poorly characterized (Evsa-T, IBEP-1, IBEP-2, IBEP-3, KPL-1). Some data obtained were verified or extended by real-time polymerase chain reaction (real-time PCR), Northern blotting, Western blotting, immunohistochemistry and cell growth studies. Clustering analysis of the low-density microarray data allowed the sorting of BCC lines into two classes and supported a major discriminatory role for ER alpha, confirming data from previous studies. A few genes that are highly and specifically expressed in one cell line were identified, such as MGB1 (mammaglobin 1) in Evsa-T cells, and PIP (prolactin-inducible protein) in MDA-MB-453 BCC, suggesting an apocrine origin for these latter cells. Two BCC lines (IBEP-1 and IBEP-3) that had been previously characterized as ER alpha-negative, were classified by the low-density microarray among ER alpha-positive lines (MCF-7, T-47D, IBEP-2, BT-474, KPL-1) and were indeed confirmed as receptor-positive (at both mRNA and protein levels) and hormone-responsive cells. In conclusion, our results support the utility of a low-density microarray approach in cases where the cost and exhaustiveness of high-density microarrays may constitute a drawback; for instance, in obtaining a rapid phenotype evaluation in cell populations freshly isolated from breast tumors.

The Prognostic Significance of Metabolic Response Heterogeneity in Metastatic Colorectal Cancer.

BACKGROUND: Tumoral heterogeneity is a major determinant of resistance in solid tumors. FDG-PET/CT can identify early during chemotherapy non-responsive lesions within the whole body tumor load. This prospective multicentric proof-of-concept study explores intra-individual metabolic response (mR) heterogeneity as a treatment efficacy biomarker in chemorefractory metastatic colorectal cancer (mCRC). METHODS: Standardized FDG-PET/CT was performed at baseline and after the first cycle of combined sorafenib (600mg/day for 21 days, then 800mg/day) and capecitabine (1700 mg/m²/day administered D1-14 every 21 days). MR assessment was categorized according to the proportion of metabolically non-responding (non-mR) lesions (stable FDG uptake with SUVmax decrease <15%) among all measurable lesions. RESULTS: Ninety-two patients were included. The median overall survival (OS) and progression-free survival (PFS) were 8.2 months (95% CI: 6.8-10.5) and 4.2 months (95% CI: 3.4-4.8) respectively. In the 79 assessable patients, early PET-CT showed no metabolically refractory lesion in 47%, a heterogeneous mR with at least one non-mR lesion in 32%, and a consistent non-mR or early disease progression in 21%. On exploratory analysis, patients without any non-mR lesion showed a significantly longer PFS (HR 0.34; 95% CI: 0.21-0.56, P-value <0.001) and OS (HR 0.58; 95% CI: 0.36-0.92, P-value 0.02) compared to the other patients. The proportion of non-mR lesions within the tumor load did not impact PFS/OS. CONCLUSION: The presence of at least one metabolically refractory lesion is associated with a poorer outcome in advanced mCRC patients treated with combined sorafenib-capecitabine. Early detection of treatment-induced mR heterogeneity may represent an important predictive efficacy biomarker in mCRC. TRIAL REGISTRATION: ClinicalTrials.gov NCT01290926.