LKB1 loss in melanoma disrupts directional migration toward extracellular matrix cues.

Somatic inactivation of the serine/threonine kinase gene STK11/LKB1/PAR-4 occurs in a variety of cancers, including ∼10% of melanoma. However, how the loss of LKB1 activity facilitates melanoma invasion and metastasis remains poorly understood. In LKB1-null cells derived from an autochthonous murine model of melanoma with activated Kras and Lkb1 loss and matched reconstituted controls, we have investigated the mechanism by which LKB1 loss increases melanoma invasive motility. Using a microfluidic gradient chamber system and time-lapse microscopy, in this paper, we uncover a new function for LKB1 as a directional migration sensor of gradients of extracellular matrix (haptotaxis) but not soluble growth factor cues (chemotaxis). Systematic perturbation of known LKB1 effectors demonstrated that this response does not require canonical adenosine monophosphate-activated protein kinase (AMPK) activity but instead requires the activity of the AMPK-related microtubule affinity-regulating kinase (MARK)/PAR-1 family kinases. Inhibition of the LKB1-MARK pathway facilitated invasive motility, suggesting that loss of the ability to sense inhibitory matrix cues may promote melanoma invasion.

Qualitative identification of dibenzoylmethane in licorice root (Glycyrrhiza glabra) using gas chromatography-triple quadrupole mass spectrometry.

Licorice root (Glycyrrhiza glabra), an herbal Chinese medicine, has shown medicinal uses in therapeutics and cancer prevention. Dibenzoylmethane (DBM; 1, 3-diphenyl-1, 3-propadinedione), a small beta-diketone, has been reported to be a minor constituent of licorice and a known deregulator of the human prostate cancer cell cycle. Characterization of the phytochemical profiles of licorice root forms including commercially available DBM will advance our search in identifying novel reagents for prostate cancer therapeutics. Gas chromatography- triple quadrupole-mass spectrometric analysis was used for detecting DBM in licorice root extracts. DBM and all licorice forms exhibited a component with a retention time of 14.5 minutes. The major fragment ions detected were at m/z 77, 105, 147, 223 and 224 at the identified retention time by selected reaction monitoring/SRM. These data confirm the presence of DBM from its natural source (G. glabra), and the GC-MS/SRM method helps in the identification of this minor component in a complex biological matrix.