The newly identified SYLF lipid-binding domain of SH3YL1 mediates phosphoinositide binding during dorsal membrane morphogenesis.

Downregulation of cell-cell adhesion and upregulation of cell migration play critical roles in the conversion of benign tumors to aggressive invasive cancers. In this study, we show that changes in cell-cell adhesion and cancer cell migration/invasion capacity depend on the level of phosphatidylinositol 4-phosphate [PI(4)P] in the Golgi apparatus in breast cancer cells. Attenuating SAC1, a PI(4)P phosphatase localized in the Golgi apparatus, resulted in decreased cell-cell adhesion and increased cell migration in weakly invasive cells. In contrast, silencing phosphatidylinositol 4-kinase IIIb, which generates PI(4)P in the Golgi apparatus, increased cell-cell adhesion and decreased invasion in highly invasive cells. Furthermore, a PI(4)P effector, Golgi phosphoprotein 3, was found to be involved in the generation of these phenotypes in a manner that depends on its PI(4)P-binding ability. Our results provide a new model for breast cancer cell progression in which progression is controlled by PI(4)P levels in the Golgi apparatus. Cancer Res; 74(11); 3054-66. Ó2014 AACR.

Metastatic melanoma is highly resistant to drug treatment, and the underlying mechanisms of this resistance remain unclear. Increased tissue stiffness is correlated with tumor progression, but whether increased tissue stiffness contributes to treatment resistance in melanoma is not known. To investigate the effect of substrate stiffness on melanoma cell treatment responsiveness, PEG hydrogels were utilized as a cell culture system to precisely vary matrix elasticity and investigate melanoma cell responses to a commercially available pharmacological inhibitor (PLX4032). The tensile moduli were varied between 0.6 and 13.1 kPa (E) and the effects of PLX4032 on metabolic activity, apoptosis, and proliferation were evaluated on human cell lines derived from radial growth phase (WM35) and metastatic melanoma (A375). The A375 cells were found to be stiffness-independent; matrix elasticity did not alter cell morphology or apoptosis with PLX4032 treatment. The WM35 cells, however, were more dependent on substrate modulus, displaying increased apoptosis and smaller focal adhesions on compliant substrates. Culturing melanoma cells on PEG hydrogels revealed stage-dependent responses to PLX4032 that would have otherwise been masked if cultured strictly on TCPS. These findings demonstrate the utility of PEG hydrogels as a versatile in vitro culture platform with which to investigate the molecular mechanisms of melanoma biology and treatment responsiveness.

The serine/threonine kinase Akt plays a central role in cell survival and proliferation. Its activation is linked to tumorigenesis in several human cancers. Although many Akt substrates have been elucidated, the Akt-binding proteins that regulate Akt function remain unclear. We report herein having identified casein kinase 2-interacting protein-1 (CKIP-1) as an Akt pleckstrin homology (PH) domain-binding protein with Akt inhibitory function. CKIP-1 formed a complex with each Akt isoform (Akt1, Akt2, and Akt3) via its NH 2 terminus. Dimerization of CKIP-1 via its leucine zipper (LZ) motif at the COOH terminus was found to be associated with Akt inactivation because deletion of the LZ motif eliminated Akt inhibitory function, although it could still bind to Akt. Expression of the NH 2 terminus-deleted CKIP-1 mutant containing the LZ motif, but lacking Akt-binding ability, induced Akt phosphorylation and activation by sequestering the ability of endogenous CKIP-1 to bind to Akt. Stable CKIP-1 expression caused Akt inactivation and cell growth inhibition in vitro. In addition, the growth of stable CKIP-1 transfectants xenografted into nude mice was slower than that of mock transfectants. These results indicate that CKIP-1, a novel Akt PH domain-interacting protein, would be a candidate of tumor suppressor with an Akt inhibitory function. [Cancer Res 2007;67(20):9666-76]

BackgroundLiquid biopsy approaches, such as measuring circulating tumour cells (CTCs), have recently been introduced in several clinical studies. However, the development of CTCs as a predictive marker for treatment effects on breast cancer remains an enormous task. We investigated CTCs, including epithelial mesenchymal transition (EMT) status, from metastatic breast cancer patients who had received eribulin-based treatment, which reportedly suppresses EMT as a means of tumour suppression. Our aim was to test the possibility of this method serving as a tool predicting eribulin efficacy.MethodsTwenty-two patients were enrolled and peripheral blood samples were collected before eribulin treatment. CTCs were then examined using a Microfluidic Chip device. CTCs positive for vimentin and pan-cytokeratin were defined as mesenchymal and epithelial CTCs, respectively. Progression-free survival (PFS) and clinical response were assessable in 20 and 18 patients, respectively, in relation to the number of CTCs.ResultsNumbers of total CTCs were significantly increased in patients with progressive disease during treatment (p = 0.006). Median PFS was 14.6 weeks and patients with more total and mesenchymal CTCs at baseline had significantly shorter PFS (p = 0.0013 and 0.013, respectively). Multivariate logistic regression analysis revealed small number of total baseline CTCs and long disease-free survival to be related to long PFS (p = 0.0004 and 0.020, respectively).ConclusionsOur data suggest that determining both mesenchymal and epithelial CTCs at baseline might be a good tool for predicting eribulin responsiveness. Evaluation of mesenchymal CTC can be considered as a parameter in larger studies, while most clinical trials are currently employing only the detection of the epithelial cellular adhesion molecule (EpCAM).Electronic supplementary materialThe online version of this article (10.1186/s12967-018-1663-8) contains supplementary material, which is available to authorized users.