Glucocorticoids promote lung metastasis of pancreatic cancer cells through enhancing cell adhesion, migration and invasion.

Glucocorticoids (GCs) are the important stress hormones and widely prescribed as drugs. Although stress has been suggested as a promoter of tumor progression, the direct influence of GCs on metastasis of tumor is not fully understood. Metastasis is a major cause of death in pancreatic cancer patients. In the present study, we investigated the effect of GCs on progression of pancreatic cancer and elucidated the underlying mechanism. It was found that GCs significantly promote cell adhesion, migration, and invasion of pancreatic cancer cells in vitro and their lung metastasis in vivo. Further mechanistic studies showed that GCs notably up-regulate the expression of a trans-membrane glycoprotein, mucin 1 (MUC1) and increase the activation of AKT. Inhibiting MUC1 expression not only attenuates the activation of AKT, but also significantly reduces the promoting effects of GCs on cell adhesion, migration, invasion, and lung metastasis of pancreatic cancer cells. Moreover, GCs not only significantly up-regulate expression of Rho-associated kinase 1/2 (ROCK1/2) and matrix metalloproteinase 3 and 7 (MMP3/7), but also activate ROCK2, which are also involved in the pro-migratory and pro-invasive effects of GCs in pancreatic cancer cells. Taken together, our findings reveal that GCs promote metastasis of pancreatic cancer cells through complex mechanism. MUC1-PI3K/AKT pathway, ROCK1/2 and MMP3/7 are involved in the promoting effect of GCs on cell migration, invasion and metastasis in pancreatic cancer cells. These results suggest the importance of reducing stress and GCs administration in patients with pancreatic cancer to avoid an increased risk of cancer metastasis.

Up-regulation of Rho-associated kinase 1/2 by glucocorticoids promotes migration, invasion and metastasis of melanoma.

Although glucocorticoids (GCs) regulate proliferation, differentiation and apoptosis of tumor cells, their influence on metastasis of tumor cells is poorly understood. Melanoma is a type of skin cancers with high metastasis. We investigated the effect of GCs on metastasis of melanoma cells and its mechanism. We found that GCs significantly promoted the adhesion, migration, invasion of melanoma cells in vitro and lung metastasis in experimental melanoma metastasis mice. Dexamethasone (Dex), a synthetic GC, did not change the RhoA, RhoB and RhoC signalings, but significantly increased the expression and activity of Rho-associated kinase 1/2 (ROCK1/2). The effect of Dex was to increase ROCK1/2 stability mediated by glucocorticoid receptor. Inhibiting ROCK1/2 activity with Y-27632, a ROCK1/2 inhibitor abrogated the pro-migration and pro-metastasis effects of GCs in vitro and in vivo, indicating that ROCK1/2 mediated the pro-metastasis effects of GCs. Activation of PI3K/AKT also contributed to the pro-migration and pro-invasion effects of Dex partially through up-regulating ROCK1/2 expression. Additionally, Dex also down-regulated the expression of tissue inhibitors of matrix metalloproteinase-2. Taken together, our findings provide new data to understand the possible promoting roles and mechanisms of GCs in melanoma metastasis.

Correlation between activation of PI3K/AKT/mTOR pathway and prognosis of breast cancer in Chinese women.

BACKGROUND: Abnormal activation of PI3K/AKT/mTOR (PAM) pathway, caused by PIK3CA mutation, KRAS mutation, PTEN loss, or AKT1 mutation, is one of the most frequent signaling abnormalities in breast carcinoma. However, distribution and frequencies of mutations in PAM pathway are unclear in breast cancer patients from the mainland of China and the correlation between these mutations and breast cancer outcome remains to be identified. METHODS: A total of 288 patients with invasive ductal breast cancer were recruited in this study. Mutations in PIK3CA (exons 4, 9 and 20), KRAS (exon 2) and AKT1 (exon 3) were detected using Sanger sequencing. PTEN loss was measured by immunohistochemistry assay. Correlations between these genetic aberrations and clinicopathological features were analyzed. RESULTS: The frequencies of PIK3CA mutation, KRAS mutation, AKT1 mutation and PTEN loss were 15.6%, 1.8%, 4.4% and 35.3%, respectively. However, except for PTEN loss, which was tied to estrogen receptor (ER) status, these alterations were not associated with other clinicopathological features. Survival analysis demonstrated that PIK3CA mutation, PTEN loss and PAM pathway activation were not associated with disease-free survival (DFS). Subgroup analysis of patients with ER positive tumors revealed that PIK3CA mutation more strongly reduced DFS compared to wild-type PIK3CA (76.2% vs. 54.2%; P = 0.011). PIK3CA mutation was also an independent factor for bad prognosis in ER positive patients. CONCLUSIONS: AKT1, KRAS and PIK3CA mutations and PTEN loss all exist in women with breast cancer in the mainland China. PIK3CA mutation may contribute to the poor outcome of ER positive breast carcinomas, providing evidence for the combination of PI3K/AKT/mTOR inhibitors and endocrine therapy.

Up-regulation of stomatin expression by hypoxia and glucocorticoid stabilizes membrane-associated actin in alveolar epithelial cells.

Stomatin is an important lipid raft-associated protein which interacts with membrane proteins and plays a role in the membrane organization. However, it is unknown whether it is involved in the response to hypoxia and glucocorticoid (GC) in alveolar epithelial cells (AEC). In this study we found that hypoxia and dexamethasone (dex), a synthetic GC not only up-regulated the expression of stomatin alone, but also imposed additive effect on the expression of stomatin in A549 cells, primary AEC and lung of rats. Then we investigated whether hypoxia and dex transcriptionally up-regulated the expression of stomatin by reporter gene assay, and found that dex, but not hypoxia could increase the activity of a stomatin promoter-driven reporter gene. Further deletion and mutational studies demonstrated that a GC response element (GRE) within the promoter region mainly contributed to the induction of stomatin by dex. Moreover, we found that hypoxia exposure did not affect membrane-associated actin, but decreased actin in cytoplasm in A549 cells. Inhibiting stomatin expression by stomatin siRNA significantly decreased dense of peripheral actin ring in hypoxia or dex treated A549 cells. Taken all together, these data indicated that dex and/or hypoxia significantly up-regulated the expression of stomatin in vivo and in vitro, which could stabilize membrane-associated actin in AEC. We suppose that the up-regulation of stomatin by hypoxia and dex may enhance the barrier function of alveolar epithelia and mediate the adaptive role of GC to hypoxia.

[Mixed infection and risk factors in children with severe adenovirus pneumonia].

OBJECTIVE: To investigate the mixed infection and analyze risk factors in children with severe adenovirus pneumonia. METHODS: A retrospective analysis was performed on the clinical data of 756 children with adenovirus pneumonia between June 2009 and June 2011. Pathogens and risk factors were studied in 216 severe cases. RESULTS: Of the 216 severe cases, 138 (63.9%) were aged from 6 months to 2 years, and 161 (74.5%) developed the disease in the winter and spring; 177 (81.9%) were affected by 1-4 pathogens besides adenovirus, including 74 cases (34.3%) infected with one pathogen as an addition. A total of 334 pathogen strains were identified from the respiratory secretions and sera of the 216 cases. Of them, 163 (48.8%) were bacterial strains, dominated by Gram-negative bacteria (124 strains), 108 (32.3%) were viral strains, and 40 (12.0%) were fungal strains. Multivariate logistic regression analysis indicated that congenital heart disease, congenital airway abnormalities, nutritional anemia, recurrent pulmonary infection, and surgical history were the independent risk factors for severe adenovirus pneumonia in children, with odds ratios of 3.3, 11.1, 7.2, 14.3 and 12.9 respectively (P<0.05). CONCLUSIONS: Severe adenovirus pneumonia is mostly seen in children aged from 6 months to 2 years and occurs frequently in the winter and spring. Many cases are also infected with other pathogens, most commonly Gram-negative bacteria. Congenital heart disease, congenital airway abnormalities, nutritional anemia, recurrent pulmonary infection and surgical history are the independent risk factors for severe adenovirus pneumonia in children.