5829

PXN

paxillin;PXN;paxillin

-

12q24.31

protein-coding

OBJECTIVE: To study the expression of paxillin in the two subgroups of human breast cancer cells with high and low metastatic potentialities and the effect of paxillin on tumor metastasis and adhesion. METHODS: Human breast cancer MDA-MB-435s cells were cultured in Transwell chamber with artificial matrigel, two subgroups of MDA-MB-435s cells with different metastatic potentiality were obtained by the ability of cells penetrating artificial matrigel. The expressions of paxillin mRNA and protein were examined by Immune histochemistry, Western blot and RT-PCR. The adhesion rates of the cells were examined by MTT. RESULTS: It was revealed by Immune histochemistry, Western blot, and RT-PCR that the expressions of paxillin at mRNA and protein levels were significantly higher in the cells with high metastatic potentiality. The difference was significant (t = 25.02,10.10, 17.18, P < 0.01). The adhesion rate was higher in the cells with high metastatic potentiality, and the difference was significant (F = 41.87, P < 0.01). CONCLUSION: The expression of paxillin may play an important role in human breast cancer metastasis and adhesion.

MLK3 kinase activates multiple mitogen-activated protein kinases and plays a critical role in cancer cell migration and invasion. In the tumor microenvironment, prometastatic factors drive breast cancer invasion and metastasis, but their associated signaling pathways are not well-known. Here, we provide evidence that MLK3 is required for chemokine (CXCL12)-induced invasion of basal breast cancer cells. We found that MLK3 induced robust phosphorylation of the focal adhesion scaffold paxillin on Ser 178 and Tyr 118, which was blocked by silencing or inhibition of MLK3-JNK. Silencing or inhibition of MLK3, inhibition of JNK, or expression of paxillin S178A all led to enhanced Rho activity, indicating that the MLK3-JNK-paxillin axis limits Rho activity to promote focal adhesion turnover and migration. Consistent with this, MLK3 silencing increased focal adhesions and stress fibers in breast cancer cells. MLK3 silencing also decreased the formation of breast cancer lung metastases in vivo, and breast cancer cells derived from mouse lung metastases showed enhanced Ser 178 paxillin phosphorylation. Taken together, our findings suggest that the MLK3-JNK-paxillin signaling axis may represent a potential therapeutic target and/or prognostic marker in breast cancer metastasis.

BACKGROUND: Colorectal carcinoma is one of the most common malignant tumors. Despite advances in therapy, mortality is still very high. The aim of this study was to evaluate the expression of paxillin in the human colon adenocarcinoma cell line SW480 and its role in cell cycle and apoptosis. We also investigated the expression of paxillin in colorectal carcinoma tissues and its relationship to clinicopathological features and survival. METHODS: Paxillin short hairpin RNA (shRNA) was constructed and transfected into the colon adenocarcinoma cell line SW480. The influence of paxillin shRNA on the cell cycle and cell apoptosis was analyzed by flow cytometry. Immunohistochemistry staining was used to assess the expression of paxillin and its association with the expression of carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19-9, p53 and Bcl-2 in 102 patients with primary colorectal carcinoma. Western blotting was also used to investigate the expression of paxillin. Medical records were reviewed and a clinicopathological analysis was performed. RESULTS: In vitro, the percentage of cells in S phase was (45.23+/-1.05)%, (43.53+/-1.23)%, and (36.13+/-0.57)% in the blank control group, negative control group, and paxillin shRNA group respectively. It was significantly decreased in the paxillin shRNA group (P = 0.000). The early apoptosis index of the paxillin shRNA group (17.2+/-1.18%) was significantly increased compared to the control shRNA group ((13.17+/-1.15)%, P = 0.013). Paxillin was positive in 71 (69.6%) patients, and it was found to be overexpressed in tumor tissues compared with normal adjacent tissues. Paxillin positive rate was higher in patients who are less than 50-years old (100.0% vs. 65.6%, P = 0.016). Paxillin expression was associated with a high histologic grade of carcinoma (81.4% vs. 61.0%, P = 0.031), a high rate of regional lymph node metastasis (22.5% vs. 13.0%, P = 0.031), mesenteric artery lymph node metastasis (100.0% vs. 64.8%, P = 0.008), distant metastasis (94.1% vs. 64.7%, P = 0.016) and a high tumor Node metastasis (TNM) stage (94.1%, 73.2%, 60.0%, and 50%, P = 0.030). Multivariate analyses revealed that recurrence was associated with the rate of regional lymph node metastasis (P = 0.001) and paxillin expression (P = 0.024). Multivariate analysis indicated that the overall survival is related to the TNM stage (P = 0.000). CONCLUSIONS: In vitro, paxillin may promote cell proliferation and inhibit apoptosis in SW480 cells. Paxillin may be a potential metastasis predictor, and an independent prognosis factor of recurrence. It may also be related to poor patient outcomes, but was not an independent predictor of survival.

The objective of the present study was to investigate the expression of paxillin and focal adhesion kinase (FAK) mRNA in esophageal carcinoma tissues, and their relationship with clinicopathological parameters, as well as to analyze the correlation of paxillin and FAK mRNA levels in esophageal carcinoma. By using reverse transcription polymerase chain reaction (RT-PCR), the mRNA expression levels of paxillin and FAK were detected in 121 samples of esophageal carcinoma, 43 samples of atypical hyperplasia and 56 samples of normal esophageal mucosa. The results showed that the positive rates of paxillin and FAK mRNA expression in esophageal carcinoma were 87.6 and 80.17%, respectively, which were significantly higher (P<0.05) than those in atypical hyperplasia (44.19 and 39.53%) and normal esophageal mucosa (5.36 and 12.5%). Notably, paxillin and FAK mRNA expression levels were significantly correlated with the differentiation degree and depth of invasion of esophageal carcinoma and with lymph node metastasis (P<0.05). In addition, paxillin and FAK mRNA expression levels in esophageal carcinoma were positively correlated (r=0.4804, P=0.000). In conclusion, the combined detection of paxillin and FAK mRNA expression is expected to provide a theoretical basis for the molecular diagnosis of esophageal carcinoma.

AIM: To evaluate the relationship of expression of paxillin, syndecan-1 and EMMPRIN proteins with clinicopathological features in hepatocellular carcinoma (HCC). METHODS: Fifty-one patients who underwent HCC resection were recruited in the study. Paxillin, syndecan-1 and EMMPRIN proteins in HCC tissues were detected with immunohistochemical staining. RESULTS: Of 51 cases of HCC, 23 (45%) exhibited paxillin protein positive expression. Of 42 cases of adjacent non-tumor liver tissues, 24 (57%) exhibited positive expression. Positive paxillin protein expression was associated with low differentiation (r = 0.406, P = 0.004), with the presence of portal vein thrombosis (r = 0.325, P = 0.021), with extra-hepatic metastasis (r = 0.346, P = 0.014). Of 51 cases of HCC, 28 (55%) exhibited syndecan-1 protein positive expression. Of 42 cases of adjacent non-tumor liver tissues, 23 (55%) exhibited positive expression. Positive snydecan-1 protein expression was associated with well differentiation (r = 0.491, P = 0.001), with no extra-hepatic metastasis (r = 0.346, P = 0.014). Of 51 cases of HCC, 28 (55%) exhibited EMMPRIN protein positive expression. Of 42 cases of adjacent non-tumor liver tissues, 21 (50%) exhibited positive expression. expression of EMMPRIN protein was not associated with serum AFP level, HBsAg status, presence of microsatellite nodule, tumor size, presence of cirrhosis and necrosis, differentiation, presence of portal vein thrombosis, extra-hepatic metastasis, disease-free survival and overall survival (P>0.05). expression of paxillin protein was correlated conversely with the expression of syndecan-1 protein in HCC (r = -0.366, P = 0.010). CONCLUSION: expression of paxillin and syndecan-1 proteins in HCC may affect its invasive and metastatic ability of the tumor. There may be a converse correlation between the expression of paxillin and syndecan-1 protein in HCC. expression of EMMPRIN protein may be detected in HCC, but it may play little role in the invasion and metastasis of HCC.

To acquire information on signal alteration corresponding to the changes in metastatic potential, we analysed protein tyrosine phosphorylation of low- and high-metastatic human osteosarcoma HuO9 sublines, which were recently established as the first metastatic model of human osteosarcoma. Tyrosine phosphorylation of proteins around 60, 70, and 120-130 kDa was enhanced in high-metastatic sublines. Among these proteins, the protein around 70 kDa, which was most remarkably phosphorylated, was identified as paxillin, a scaffold protein in integrin signaling. Activity of Src family kinase correlated well with metastatic potential, and a Src family kinase inhibitor, PP2, not only abolished tyrosine phosphorylation of paxillin but also impaired the motility of high-metastatic sublines. The expression of paxillin was also elevated in high-metastatic sublines, and knocking down of paxillin expression by RNAi method resulted in attenuated motility of high-metastatic cells. We also demonstrated that the phosphorylated form of paxillin is essential for the migration-promoting effect in human osteosarcoma. These findings suggest that enhanced activity of Src family kinases and overexpression of paxillin synergistically contribute to the high metastatic potential of human osteosarcoma through the hyperphosphorylation of paxillin.

AIMS: To investigate the relationship between paxillin expression and clinicopathological features and metastasis in salivary adenoid cystic carcinoma (SACC). METHODS: A total of 47 SACC were assessed histochemically for paxillin expression. Paxillin immunoreactivity was compared with histological type, clinical stage and distant metastasis. RESULTS: Paxillin expression was identified in 57.45% of SACC as cytoplasmic staining and the expression was correlated with distant metastasis and clinical stage (P < 0.05), but not with histological type. CONCLUSIONS: Our observations indicate that paxillin expression is upregulated in SACC. High expression of paxillin was correlated with a more advanced stage and metastasis in SACC, suggesting that paxillin is a disease marker in advanced SACC and SACC with distant metastasis, and, consequently, may have value as a therapeutic target for SACC.