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Background: The aim of the current study was to examine the role of semaphorin 3C (SEMA3C) in breast cancer., Materials and Methods: SEMA3C transcripts expressed by breast tissues were determined using real-time polymerase chain reaction (PCR). Knock-down of SEMA3C was performed in MDA-MB-231 and MCF-7 breast cancer cell lines using anti-SEMA3C hammerhead ribozyme transgenes. The effect of SEMA3C knockdown on cancer cells was determined using in vitro cellular function assays., Results: Higher SEMA3C transcript levels were significantly associated with poor differentiation of cancer cells, and transcript levels were significantly reduced in oestrogen receptor-positive tumours. Knock-down of SEMA3C expression resulted in a decrease in cell proliferation, adhesion and invasion of breast cancer cells., Conclusion: Higher SEMA3C expression is correlated with tumour differentiation. Inhibition of SEMA3C reduces adhesion and invasion of breast cancer cells. This suggests that SEMA3C may play a significant role in morphological changes of cancer cells, leading to enhanced growth and dissemination., (Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)

Background/aim: The ribosomal S6 protein kinase (RSK) family is an important effector of extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) that could influence tumour metastasis by phosphorylating proteins in both the nuclear and cytoplasmic compartments. Aberrant expression of RSK is evident in certain malignancies but the role played by RSK in breast cancer is still not clear. This study aimed to examine the expression of RSK in human breast cancer specimens and its role to breast cancer metastasis., Materials and Methods: The expression of RSK1 to -3 were separately examined in human breast cancer tissues (normal, n=33; cancer, n=112) using quantitative real-time polymerase chain reaction (Q-PCR) and immunohistochemistry. Migration and adhesion of breast cancer cells treated with the RSK inhibitor SL0101 were investigated by electric cell impedance sensing (ECIS). The effect on growth and invasion of RSK1-3 was then investigated using in vitro models., Results: The clinical data and immunohistochemistry revealed that expression of RSK1 and RSK3 were less in tumour tissues than normal. mRNA expression of RSK2 was negatively correlated with grade, TNM staging, and survival rate. SL0101 inhibited adhesion of the MCF-7 and MDA-231 breast cancer cell lines. SL0101 suppressed MDA-231 invasion and the alternate RSK inhibitor BRD7389 inhibited the invasion of MCF-7 and MDA-231 cells., Conclusion: RSK1 and 3 but not RSK2 are down-regulated in breast tumour and are associated with disease progression. RSK may be a key component in the progression and metastasis of breast cancer., (Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)

Phosphoinositide 3-kinase enhancer (PIKE) belongs to a family of GTP-binding proteins, including three isoforms, PIKE-S, PIKE-L and PIKE-A. PIKE-S and PIKE-L interact with PI3K to enhance the activity of PI3K, but PIKE-A directly binds to AKT and up-regulates its activity. PIKEs also interacts with a variety of signaling molecules in addition to PI3K and AKT, to trigger multiple physiological functions. Overexpression or mutation of PIKE has been observed in a variety of tumors, especially PIKE-A, which acts as a proto-oncogene, promoting cancer cell growth, transformation and invasion through AKT signaling. Knockdown of PIKE-A or blocking of PIKE-A/AKT interactions enhances apoptosis, inhibits cancer cell proliferation, migration and invasion. Moreover, PIKE plays an important role in tumorigenesis through other signaling pathways, such as focal adhesion kinase, signal transducer and activator of transcription 5A, and nuclear factor kappa-light-chain-enhancer of activated B cells. The current review explores the functional role of PIKE and its potential in cancer therapy., (Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)

Background: Occludin is an integral membrane protein localised at tight junctions (TJ). There is no consensus regarding its paramount role in TJ. In previous work we showed that occludin is aberrantly expressed in both human breast tissues and cancer cell lines. This study demonstrates a link to bone metastasis in human cancer., Materials and Methods: Primary breast tumours (n=124) and matched normal tissues (n=30) were processed for quantitative polymerase chain reaction (QPCR) analysis. A hammerhead ribozyme was constructed to create occludin knockdown cell lines, MDA-MB-231(ΔOcc) and PC-3(ΔOcc). The effect of human bone matrix extract (BME) was investigated using cell growth and electric cell impedance sensing (ECIS) technology to measure changes in attachment/migration. Trans-epithelial resistance (TER) was measured for assessing changes in TJ function. Cells used were MDA-MB-231, PC-3, CORL-23, SKMES-1 and A-549 human cancer cell lines., Results: Tumours from patients with bone metastasis had significantly lower occludin expression compared to those remaining alive/well (60.7±21 vs. 331±98, respectively, p=0.008). This was striking in ductal carcinomas, where patients alive/well had significantly higher occludin expression compared to those with bone metastasis (391±12.5 vs. 67.9±28, respectively, p=0.0014). ECIS demonstrated that MDA-MB-231(ΔOcc) showed reduced attachment to 5% BME compared to controls (84% vs. 100%) that prevented closure of wounded cell layers. Moreover, these cells had reduced growth on BME. In addition, BME changed the TER of a number of human cell lines and was able to effect changes in the growth of MDA-MB-241 and PC-3 cells, with greater effect on knockdown cells., Conclusion: This is the first study to demonstrate that occludin expression has a clear relationship with bone metastasis in human cancer. The discrepancy between this and the in vitro data indicating a reduction in migration/growth rate of occludin knockdown indicates that loss of occludin leads to complex changes in human cancer cell phenotype., (Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)