Osteopontin-enhanced hepatic metastasis of colorectal cancer cells.

Liver metastasis is a major cause of mortality from colorectal cancer (CRC). However, mechanisms underlying this process are largely unknown. Osteopontin (OPN) is a secreted phosphorylated glycoprotein that is involved in tumor migration and metastasis. The role of OPN in cancer is currently unclear. In this study, OPN mRNA was examined in tissues from CRC, adjacent normal mucosa, and liver metastatic lesions using quantitative real-time PCR analysis. The protein expression of OPN and its receptors (integrin αv and CD44 v6) was detected by using an immunohistochemical (IHC) method. The role of OPN in liver metastasis was studied in established colon cancer Colo-205 and SW-480 cell lines transfected with sense- or antisense-OPN eukaryotic expression plasmids by flow cytometry and cell adhesion assay. Fluorescence redistribution after photobleaching (FRAP) was used to study gap functional intercellular communication (GJIC) among OPN-transfected cells. It was found that OPN was highly expressed in metastatic hepatic lesions from CRC compared to primary CRC tissue and adjacent normal mucosa. The expression of OPN mRNA in tumor tissues was significantly related with the CRC stages. OPN expression was also detected in normal hepatocytes surrounding CRC metastatic lesions. Two known receptors of OPN, integrin αv and CD44v6 proteins, were strongly expressed in hepatocytes from normal liver. CRC cells with forced OPN expression exhibited increased heterotypic adhesion with endothelial cells and weakened intercellular communication. OPN plays a significant role in CRC metastasis to liver through interaction with its receptors in hepatocytes, decreased homotypic adhesion, and enhanced heterotypic adhesion

Expression of integrin αv and CD44v6 in normal hepatocytes with Immunohistochemistry. a,

<p>In <i>IHC</i>, integrin αv proteins (brown positive stain) were localized in cytoplasm of hepatocytes (×400). <b>b,</b> CD44v6 proteins (brown positive stain) were localized in cytoplasm of hepatocytes (×400).</p

OPN mRNA location in CRC and its liver metastasis with in situ mRNA hybridization. a,

<p>In <i>ISH</i>, the positive stain presents blue-purple under microscope. The OPN mRNA, which indicates a positive signal, was found in cytoplasm of CRC cells in primary lesions (×400). <b>b,</b> The stain in adjacent normal colorectal tissues was negative (×400). <b>c,</b> OPN mRNA was found in cytoplasm of CRC cells liver metastatic tissue. Adjacent normal liver tissues stains negative (×100).</p

Gap junctional intercellular communication (GJIC) with gap-FRAP in SW-480-pcDNA3.1(+) and SW-480-pcDNA3.1(+) OPN cells. a1,

<p>uniform fluorescence intensity before photobleaching in SW-480-pcDNA3.1(+). <b>a2,</b> weakened fluorescence intensity after photobleaching in SW-480-pcDNA3.1(+). <b>a3,</b> fluorescence redistribution after 10minutes in SW-480-pcDNA3.1(+). <b>b1,</b> uniform fluorescence intensity before photobleaching SW-480-pcDNA3.1(+) OPN cells. <b>b2,</b> weakened fluorescence intensity after photobleaching SW-480-pcDNA3.1(+) OPN cells. <b>b3,</b> faint fluorescence redistribution after 10minutes SW-480-pcDNA3.1(+) OPN cells. <b>c,</b> The percentage of fluorescence redistribution after photobleaching (FRAP%) in SW-480-pcDNA3.1(+) and SW-480-pcDNA3.1(+) OPN cells<b>.</b> After 5 minutes of photobleaching, the percentage of fluorescence redistribution after photobleaching (FRAP%) 24.65±4.08% in SW-480-pcDNA3.1(+) -OPN compared 44.74±6.23% in SW-480-pcDNA3.1(+)(<i>t</i> = 17.07, <i>P</i><0.001), and after 10 minutes, the FRAP% was still be inhibited at 25.98±4.48% in SW-480-pcDNA3.1(+) -OPN while it was redistributed to 64.92%±5.39% in the SW-480-pcDNA3.1(+) cells (<i>t</i> = 35.16, <i>P</i><0.001).</p

OPN protein localization in the CRC and its liver metastasis visualized by immunohistochemistry. a

<p>In <i>IHC</i>, OPN proteins (brown positive stain) were localized in cytoplasm of CRC cells in primary lesions(x200). <b>b</b> Adjacent normal colorectal tissues were negative(x200). <b>c</b> Positive stain was found both in CRC cells and adjacent normal hepatocytes in liver metastatic tissues(x100). <b>d</b> As controls, OPN proteins stain in normal liver tissues without CRC metastasis was negative(x100).</p

Study on grid inefficiency for mesh-type Frisch-grid ionization chambers

In this study, the grid inefficiency $$\sigma$$ for a mesh-type Frisch-grid ionization chamber (FGIC) was investigated using the finite element method and Monte Carlo method. A grid inefficiency $$\sigma$$ evaluation model was developed, which can determine the relationship between the physical parameters of the detector and the grid inefficiency with reasonable accuracy. An artificial neural network (ANN) was applied in the investigation of the grid inefficiency factor $$\sigma$$. The trained ANN was able to describe and predict the grid inefficiency factor $$\sigma$$ with different physical parameters for the mesh-type FGIC. Thus, it can serve as a reference for the development of mesh-type FGICs and correct grid inefficiency $$\sigma$$ measurements