BackgroundThe cellular apoptosis susceptibility (CAS) protein is regarded as a proliferation-associated protein that associates with tumour proliferation as it associates with microtubule and functions in the mitotic spindle checkpoint. However, there is no any actual experimental study showing CAS (or CSE1 and CSE1L) can increase the proliferation of cancer cells. Previous pathological study has reported that CAS was strongly positive stained in all of the metastasis melanoma that be examined. Thus, CAS may regulate the invasion and metastasis of cancers. CAS is highly expressed in cancers; if CAS is associated with cancer proliferation, then increased CAS expression should be able to increase the proliferation of cancer cells. We studied whether increased CAS expression can increase cancer cell proliferation and whether CAS regulates the invasion of cancer cells.MethodsWe enhanced or reduced CAS expression by transfecting CAS or anti-CAS expression vectors into human MCF-7 breast cancer cells. The proliferations of cells were determined by trypan blue exclusion assay and flow cytometry analysis. Invasion of cancer cells were determined by matrigel-based invasion assay.ResultsOur studies showed that increased CAS expression was unable to enhance cancer cell proliferation. Immunofluorescence showed CAS was distributed in cytoplasm areas near cell membrane and cell protrusions. CAS was localized in cytoplasmic vesicle and immunogold electronmicroscopy showed CAS was located in vesicle membrane. CAS overexpression enhanced matrix metalloproteinase-2 (MMP-2) secretion and cancer cell invasion. Animal experiments showed CAS reduction inhibited the metastasis of B16-F10 melanoma cells by 56% in C57BL/6 mice.ConclusionOur results indicate that CAS increases the invasion but not the proliferation of cancer cells. Thus, CAS plus ECM-degradation proteinases may be used as the markers for predicting the advance of tumour metastasis.

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Fibroblasts alter their mode of attachment and focal contact when placed on square arrays of silicon pillars. The pillars had 1-microm diameters with identical surface chemistry. Distance between pillars is 9 microm and height of pillars is 1, 5, or 10 microm on substrates. We found that these micropillars, rather than specific interactions, provided more opportunities for mechanical interlocking of the fibroblasts and acted as physical barriers that restrained cell migration. The cellular morphology and behavior is guidable by the height of pillars. In some cases, the fibroblasts filled in the intervals among several pillars; in others, a pillar protruded visibly through the cell body but did not pierce it, the cells were survived. Therefore, fibroblasts were immobilized upon in situ and the cytoplasma migrated outward to the bottom of the substrate subsequently. Laminin plays a critical role in cell attachment to the basement membrane. The results of laminin expression in fibroblasts suggest that pillar pattern appears to change cellular behavior and affect laminin expression significantly.

Human CO respiration requires rapid conversion between CO and HCO Carbonic anhydrase II facilitates this reversible reaction inside red blood cells, and band 3 [anion exchanger 1 (AE1)] provides a passage for HCO flux across the cell membrane. These 2 proteins are core components of the CO transport metabolon. Intracellular HO is necessary for CO/HCO conversion. However, abundantly expressed aquaporin 1 (AQP1) in erythrocytes is thought not to be part of band 3 complexes or the CO transport metabolon. To solve this conundrum, we used Förster resonance energy transfer (FRET) measured by fluorescence lifetime imaging (FLIM-FRET) and identified interaction between aquaporin-1 and band 3 at a distance of 8 nm, within the range of dipole-dipole interaction. Notably, their interaction was adaptable to membrane tonicity changes. This suggests that the function of AQP1 in tonicity response could be coupled or correlated to its function in band 3-mediated CO/HCO exchange. By demonstrating AQP1 as a mobile component of the CO transport metabolon, our results uncover a potential role of water channel in blood CO transport and respiration.-Hsu, K., Lee, T.-Y., Periasamy, A., Kao, F.-J., Li, L.-T., Lin, C.-Y., Lin, H.-J., Lin, M. Adaptable interaction between aquaporin-1 and band 3 reveals a potential role of water channel in blood CO transport.