Hepatocyte growth factor (HGF) protects c-met-expressing Burkitt''s lymphoma cell lines from apoptotic death induced by DNA damaging agents

The relative sensitivity of neoplastic cells to DNA damaging agents is a key factor in cancer therapy. In this paper, we show that pretreatment of Burkitt's lymphoma cell lines expressing the c-met protooncogene with hepatocyte growth factor (HGF) protects them from death induced by DNA damaging agents commonly used in tumour therapy. This protection was observed in assays based on morphological assessment of apoptotic cells and DNA fragmentation assays. The protection was dose- and time-dependent — maximal protection requiring pre-incubation with 100 ng/ml HGF for 48 h. Western blotting analysis and flow cytometric studies revealed that HGF inhibited doxorubicin- and etoposide-induced decreases in the levels of the anti-apoptotic proteins Bcl-XL, and to a lesser extent Bcl-2, without inducing changes in the pro-apoptotic Bax protein. Overall, these studies suggest that the accumulation of HGF within the microenvironment of neoplastic cells may contribute to the development of a chemoresistant phenotype.

Identification of an unknown b-agonist in feed by liquid chromatography/bioassay/quadrupole time-of-flight tandem mass spectrometry with accurate mass measurement.

A new approach to the search for residues of unknown growth promoting agents such as anabolic steroids and -agonists in feed is presented. Following primary extraction and clean-up, samples are separated using gradient liquid chromatography (LC). The effluent is split towards two identical 96-well fraction collectors and an optional electrospray quadrupole time-of-flight mass spectrometry (QTOFMS) system for accurate mass measurement. One 96-well plate is used for a bioassay (enzyme-immuno assay, receptor assay) and will detect the bioactivity and position of the relevant peak in the chromatogram. The positive well in the second 96-well plate is used for identification by LC/QTOFMS/MS. The value of this LC/bioassay/QTOFMS/MS methodology is highlighted by the finding and structure elucidation of a new -agonist in a feed extract.