SUMMARY:Extensive studies have demonstrated that transforming growth factor-beta (TGF-b ) plays an important role in the progression of renal diseases. TGF-b exerts its biological functions mainly through its downstream signalling molecules, Smad2 and Smad3. It is now clear that Smad3 is critical for TGF-b 's pro-fibrotic effect, whereas the functions of Smad2 in fibrosis in response to TGFb still need to be determined. Our recent studies have demonstrated that Smad signalling is also a critical pathway for renal fibrosis induced by other pro-fibrotic factors, such as angiotensin II and advanced glycation end products (AGE). These pro-fibrotic factors can activate Smads directly and independently of TGF-b . They can also cause renal fibrosis via the ERK/p38 MAP kinase-Smad signalling cross-talk pathway. In contrast, blockade of Smad2/3 activation by overexpression of an inhibitory Smad7 prevents collagen matrix production induced by TGF-b , angiotensin II, high glucose and AGE and attenuates renal fibrosis in various animal models including rat obstructive kidney, remnant kidney and diabetic kidney diseases. Results from these studies indicate that Smad signalling is a key and final common pathway of renal fibrosis. In addition, TGF-b has anti-inflammatory and immuneregulatory properties. Our most recent studies demonstrated that TGF-b transgenic mice are protected against renal inflammation in mouse obstructive and diabetic models. Upregulation of renal Smad7, thereby blocking NF. k B activation via induction of I k B a , is a central mechanism by which TGFb inhibits renal inflammation. In conclusion, TGF-b signals through Smad2/3 to mediate renal fibrosis, whereas induction of Smad7 inhibits renal fibrosis and inflammation. Thus, targeting Smad signalling by overexpression of Smad7 may have great therapeutic potential for kidney diseases.

The recent discovery of the angiotensin II (Ang II)-breakdown enzyme, angiotensin I converting enzyme (ACE) 2, suggests the importance of Ang II degradation in hypertension. The present study explored the signaling mechanism by which ACE2 is regulated under hypertensive conditions. Real-time PCR and immunohistochemistry showed that ACE2 mRNA and protein expression levels were high, whereas ACE expression levels were moderate in both normal kidney and heart. In contrast, patients with hypertension showed marked ACE up-regulation and ACE2 down-regulation in both hypertensive cardiopathy and, particularly, hypertensive nephropathy. The inhibition of ACE2 expression was shown to be associated with ACE up-regulation and activation of extracellular regulated (ERK)1/2 and p38 mitogen-activated protein (MAP) kinases. In vitro, Ang II was able to upregulate ACE and down-regulate ACE2 in human kidney tubular cells, which were blocked by an angiotensin II (AT)1 receptor antagonist (losartan), but not by an AT2 receptor blocker (PD123319). Furthermore, blockade of ERK1/2 or p38 MAP kinases by either specific inhibitors or a dominant-negative adenovirus was able to abolish Ang II-induced ACE2 down-regulation in human kidney tubular cells. In conclusion, Ang II is able to up-regulate ACE and down-regulate ACE2 expression levels under hypertensive conditions both in vivo and in vitro. The AT1 receptor-mediated ERK/p38 MAP kinase signaling pathway may be a key mechanism by which Ang II down-regulates ACE2 expression, implicating an ACE/ACE2 imbalance in hypertensive cardiovascular and renal damage. The prevalence of hypertension is approximately 30% based on National Health and Nutrition Examination Survey data, 1 making it one of the most important risk factors for cardiovascular disease, the major cause of mortality in the United States.The recent discovery of the angiotensin II (Ang II) breakdown enzyme angiotensin I -converting enzyme (ACE)2 and alternative Ang II-generating pathways such as chymase, in addition to ACE, has increased the complexity of our understanding of Ang II generation and degradation in hypertension. 2,3 ACE2 is a breakdown enzyme responsible for the degradation of Ang II to Angiotensin 1-7 peptide. The later has vasodilatory properties and has its own unique receptor, the Mas receptor. 3 Emerging evidence shows that ACE2 plays an important role in negatively regulating hypertension. In rat models of hypertension, renal ACE2 mRNA and protein are decreased, although this could not be confirmed in human hypertensive nephropathy in a prior study. 4 Further, in rats treated with ACE inhibitors and angiotensin receptor blockers, an increase in local renal ACE2 activity is noted. 5,6 We have shown earlier that ACE is up-regulated in human diabetic nephropathy accompanied with hypertension, a condition associated with high Ang II levels. 7 Taken together, these findings suggest that there may be an alteration in the ACE/ACE2 balance in hypertension in a manner that favors increased Ang II generation (ie, upre...

Background-Angiotensin II is a key mediator of diabetes-related vascular disease. It is now recognized that in addition to angiotensin-converting enzyme, chymase is an important alternative angiotensin II-generating enzyme in hypertension and diabetes. However, the mechanism of induction of chymase in diabetes remains unknown. Methods and Results-Here, we report that chymase is upregulated in coronary and renal arteries in patients with diabetes by immunohistochemistry. Upregulation of vascular chymase is associated with deposition of advanced glycation end products (AGEs), an increase in expression of the receptor for AGEs (RAGE), and activation of ERK1/2 MAP kinase. In vitro, AGEs can induce chymase expression and chymase-dependent angiotensin II generation in human vascular smooth muscle cells via the RAGE-ERK1/2 MAP kinase-dependent mechanism. This is confirmed by blockade of AGE-induced vascular chymase expression with a neutralizing RAGE antibody and an inhibitor to ERK1/2 and by overexpression of the dominant negative ERK1/2. Compared with angiotensin-converting enzyme, chymase contributes to the majority of angiotensin II production (Ͼ70%, PϽ0.01) in response to AGEs. Furthermore, AGE-induced angiotensin II production is blocked by the anti-RAGE antibody and by inhibition of ERK1/2 MAP kinase activities. Conclusions-AGEs

Her-2/neu or c-erbB-2, a 185-kD protein is an important prognostic indicator/target for therapy in metastatic breast carcinoma. Recent reports have also identified a role for Her-2/neu overexpression in other solid tumors. We performed a retrospective analysis to evaluate the prevalence and prognostic role of Her-2/neu overexpression in patients with glioblastoma multiforme (GBM). Data collection (chart review) included demographic information, symptoms at presentation, histologic grade, survival time, and treatment offered. Testing for Her-2/neu overexpression was performed on paraffin-embedded archival tumor tissue using immunohistochemistry (IHC) (Hercep test). An IHC score of 2+ or greater was considered overexpression. An experienced pathologist who was blinded from the clinical history performed all the IHC testing. Between 1990 and 2001, 149 subjects (68 females, 81 males) with a biopsy-proven diagnosis of GBM were identified. Age range was 26 to 79 years (mean: 64 years) and overall mean survival was 12 months. Her-2/neu overexpression was detected in 23 patients (15.4%). Interestingly, the median survival for patients whose pathologic specimens revealed Her-2/neu overexpression was 4 months compared to those who lacked overexpression, in whom survival was 8 months. After adjusting for age, performance status, smoking history, and treatment, logistic regression analysis (with a survival of <3 months as the dependent variable) revealed that Her-2/neu overexpression significantly (p < 0.01) increased the odds of early mortality (<3 months). The results of our large study indicate that Her-2/neu overexpression may be a poor prognostic marker in patients with GBM. In addition, in a proportion of subjects (15.4%), Her-2/neu may be a potential target for tumor-specific monoclonal antibody therapy. The role of trastuzumab (alone or in combination with conventional therapy) needs to be evaluated.

HER-2/neu overexpression seen in 10.4% appears to predict a slight increased mortality in patients with primary malignant brain tumors, especially glioblastoma multiforme, and is associated with a high incidence of a second primary malignancy outside the CNS. Additionally, our data suggests that other clinical variables were predictive of increased mortality, including tumor location (occipital), histology (glioblastoma), and presenting symptoms (nausea/vomiting). The large, heterogeneous sample employed in our study allows more definitive conclusions to be made with regard to the usefulness of HER-2/neu and other clinical predictors of survival in patients with primary brain tumors.