Inhibition of doxorubicin-induced HER3-PI3K-AKT signalling enhances apoptosis of ovarian cancer cells.

Resistance to chemotherapy is a serious problem for the successful treatment of ovarian cancer patients but signalling pathways that contribute to this chemoinsensitivity are largely unknown. We demonstrate that the chemotherapeutic drug doxorubicin induces activation of the HER3-PI3K-AKT signalling cascade in ovarian cancer cells. We further show that the induction of this anti-apoptotic signalling pathway is based on upregulated expression of HER3 ligands, their shedding by the metalloprotease ADAM17, and is dependent on the HER2 receptor. The doxorubicin-mediated activation of this important survival cascade can be blocked by the kinase inhibitors lapatinib or erlotinib as well as by the therapeutic monoclonal antibody trastuzumab. Inhibition of the doxorubicin-induced activation of HER3-PI3K-AKT signalling significantly increased apoptosis of ovarian cancer cells. Besides doxorubicin, treatment of cells with cisplatin resulted in activation of the HER3 receptor whereas other chemotherapeutics did not show this effect. The increase in HER3 phosphorylation was detected in well-established ovarian cancer cell lines which originate from patients previously treated with these chemotherapeutic drugs. Based on these results, we postulate that activation of the HER3-PI3K-AKT cascade represents a major mechanism of chemoresistance in ovarian cancer.

Direct genetic analysis of single disseminated cancer cells for prediction of outcome and therapy selection in esophageal cancer.

The increasing use of primary tumors as surrogate markers for prognosis and therapeutic decisions neglects evolutionary aspects of cancer progression. To address this problem, we studied the precursor cells of metastases directly for the identification of prognostic and therapeutic markers and prospectively analyzed single disseminated cancer cells from lymph nodes and bone marrow of 107 consecutive esophageal cancer patients. Whole-genome screening revealed that primary tumors and lymphatically and hematogenously disseminated cancer cells diverged for most genetic aberrations. However, we identified chromosome 17q12-21, the region comprising HER2, as the most frequent gain in disseminated tumor cells that were isolated from both ectopic sites. Survival analysis demonstrated that HER2 gain in a single disseminated tumor cell but not in primary tumors conferred high risk for early death.

Genetic alterations in the tyrosine kinase transcriptome of human cancer cell lines.

Protein tyrosine kinases (PTKs) play a critical role in the manifestation of cancer cell properties, and respective signaling mechanisms have been studied extensively on immortalized tumor cells. To characterize and analyze commonly used cancer cell lines with regard to variations in the primary structure of all expressed PTKs, we conducted a cDNA-based sequence analysis of the entire tyrosine kinase transcriptome of 254 established tumor cell lines. The profiles of cell line intrinsic PTK transcript alterations and the evaluation of 155 identified polymorphisms and 234 somatic mutations are made available in a database designated "Tykiva" (tyrosine kinome variant). Tissue distribution analysis and/or the localization within defined protein domains indicate functional relevance of several genetic alterations. The cysteine replacement of the highly conserved Y367 residue in fibroblast growth factor receptor 4 or the Q26X nonsense mutation in the tumor-suppressor kinase CSK are examples, and may contribute to cell line-specific signaling characteristics and tumor progression. Moreover, known variants, such as epidermal growth factor receptor G719S, that were shown to mediate anticancer drug sensitivity could be detected in other than the previously reported tumor types. Our data therefore provide extensive system information for the design and interpretation of cell line-based cancer research, and may stimulate further investigations into broader clinical applications of current cancer therapeutics.

ErbB-3 predicts survival in ovarian cancer.

BACKGROUND: HER3 (erbB-3) is a member of the epidermal growth factor receptor (EGFR) family. After dimerization with other members of the EGFR family several signal transduction cascades can be activated, including phosphoinosite 3'-kinase (PI3-K)/Akt and extracellular signal-regulated kinase (ERK1/2). Here, we studied a possible association between HER3 expression and prognosis in patients with ovarian cancer. METHODS: Tumor tissue of 116 consecutive patients diagnosed with primary epithelial ovarian cancer between 1986 and 1995 was analyzed immunohistochemically for HER3 expression. A possible influence of HER3 expression on survival was studied by multivariate Cox regression adjusting for established clinical prognostic factors. RESULTS: A positive HER3 expression was observed in 53.4% of the patients. HER3 expression was associated with decreased survival in proportional hazard modeling, including the International Federation of Gynecology and Obstetrics (FIGO) stage, histologic grade and type, residual disease, and age. After likelihood ratio forward as well as backward selection, only HER3 expression (hazard ratio, 1.71; 95% CI, 1.10 to 2.67; P = .018), FIGO stage (hazard ratio, 4.78; 95% CI, 1.89 to 12.08; P = .001), residual tumor (hazard ratio, 2.69; 95% CI, 1.40 to 5.17; P = .003), and age (hazard ratio, 2.06; 95% CI, 1.17 to 3.65; P = .013) were found to be significant. Kaplan-Meier plots demonstrated a clear influence of HER3 expression on survival time. Median survival time was 3.31 years (95% CI, 1.93 to 4.68) for patients with low HER3 expression, compared with only 1.80 years (95% CI, 0.83 to 2.78) for patients with HER3 overexpression (log-rank test P = .0034). CONCLUSION: HER3 may represent a new prognostic factor in primary epithelial ovarian cancer. Pending validation, exploration of therapeutic strategies to block HER3 could be warranted.

Geometric organization of the extracellular matrix in the control of integrin-mediated adhesion and cell function in osteoblasts.

Cell-extracellular matrix (ECM) interactions play a central role in tissue architecture and turnover. Particularly, integrin-mediated cell adhesion participates in biochemical and physical signals. The aim of this study is to investigate the importance of ECM organization for alveolar bone osteoblasts adhesion and to determine the effects on cell functions such as collagen and fibronectin production. By applying new concepts from the nanotechnology to biological systems, we have developed materials decorated with nano-patterns of peptides of the ECM arranged at a distance of 58 or 73 nm. On these surfaces, human osteoblasts from alveolar bone were cultured for 1-96 hr and examined by video and fluorescence microscopy. Protein quantification by western blotting and gene expression by RT-PCR were also performed. Good cell adhesion and spreading was observed on the 58 nm pattern after 30 min, while weak adhesion and increased motility was evident in osteoblasts on the 73 nm pattern, leading to alteration of cell shape and reduction of cell area after 24 hr. Moreover, cells on the 73 nm did not form focal adhesions and failed to organize the cytoskeleton. After 96 hr in culture, osteoblasts on the 73 nm retained intracellular collagen and produced a disorganized fibronectin network. Osteoblast adhesion and intra-and extra-cellular molecules reorganization are regulated not only by the composition but also by the structure of the extracellular environment. Our novel in vitro system makes it possible to elucidate some of the mechanisms necessary for the maintenance of tissue architecture and mechanical strength, as well as for the design of artificial materials for future clinical applications.