Abstract-Unlike the ubiquitous angiotensin-converting enzyme (ACE), the ACE-related carboxypeptidase 2 (ACE 2) is predominantly expressed in the heart, kidney, and testis. ACE 2 degrades angiotensin (Ang) II to Ang (1-7) and Ang I to Ang (1-9). We investigated the expression of ACE and ACE 2 in a rodent model of type 2 diabetes. ACE and ACE 2 were measured in kidney and heart from 8-week-old no diabetic control (db/m) mice and diabetic (db/db) mice, which at this young age have obesity and hyperglycemia without nephropathy. Key Words: angiotensin-converting enzyme Ⅲ renin-angiotensin system Ⅲ diabetic nephropathy Ⅲ obesity Ⅲ mice Ⅲ ACE-related carboxypeptidase 2 A lterations within the renin-angiotensin system (RAS) are considered to be pivotal for the development of diabetic complications, particularly diabetic renal disease and hypertension. 1-4 The angiotensin-converting enzyme (ACE), a key element of RAS, is primarily a membrane-bound protein residing on the surface of epithelial and endothelial cells. 5 Through its 2 catalytic domains, ACE cleaves the inactive precursor angiotensin (Ang) I to Ang II, which induces vasoconstriction, aldosterone release, and acts as growth modulator. [5][6][7] Most tissue beds, including the kidney, express a local RAS that acts independently of the circulating system. [7][8][9] There is also a growing body of evidence that implicates the more recently characterized peptides Ang (1-7) and Ang (3-8) as additional bioactive components of the RAS. 10 -12 Recently, a homologue of ACE, an ACE-related carboxypeptidase (ACE 2), has been identified in humans and rodents. [13][14][15] It contains only a single enzymatic site that is capable of catalyzing Ang I to Ang (1-9). It also degrades Ang II to the vasodilator Ang (1-7) and this may counterbalance the Ang II-forming activity of ACE. 15,16 In contrast to ACE, ACE 2 activity is not inhibited by ACE inhibitors. 13 Previous studies using the streptozocin (STZ) model of diabetes revealed decreased renal expression of ACE. [17][18][19] A recent study using this rat diabetic model showed a reduction in ACE 2 as well. 18 These previous studies involved diabetic rats with advanced renal lesions. [17][18][19] The aim of the present study was to characterize the expression of ACE and ACE 2 in kidney from diabetic mice (db/db) before the development of nephropathy. The db/db mouse is a genetic model of type 2 diabetes caused by an inactivating mutation of the leptin receptor gene that results in a shorter intracellular domain of the receptor and a failure to transduce signals. 20,21 As a result of this mutation, hyperglycemia develops in association with insulin resistance and obesity at Ϸ4 to 7 weeks after birth. 22 The db/db mouse eventually has some, but not all, features of

Purpose To assess the clinical and pathological significance of mast cell infiltration in human pancreatic cancer and evaluate crosstalk between mast cells and cancer cells in vitro. Experimental Design Immunohistochemistry for tryptase was performed on 53 pancreatic cancer specimens. Mast cell counts were correlated with clinical variables and survival. Serum tryptase activity from cancer patients was compared to patients with benign pancreatic disease. In vitro, the effect of pancreatic cancer conditioned media on mast cell migration was assessed. The effect of conditioned media from the human mast cell line, LAD-2, on cancer and normal ductal cell proliferation was assessed by thymidine incorporation. Matrigel invasion assays were used to evaluate the effect of mast cell conditioned media on cancer cell invasion in the presence and absence of a matrix metalloproteinase inhibitor, GM6001. Results Mast cell infiltration was significantly increased in pancreatic cancer compared to normal pancreatic tissue [11.4±6.7vs.2.0±1.4(p<0.001)]. Increased infiltrating mast cells correlated with higher grade tumors (p<0.0001) and worse survival. Patients with pancreatic cancer had elevated serum tryptase activity (p<0.05). In vitro, AsPC1 and PANC-1 cells induced mast cell migration. Mast cell conditioned media induced pancreatic cancer cell migration, proliferation and invasion but had no effect on normal ductal cells. Furthermore, the effect of mast cells on cancer cell invasion was in large part MMP-dependent. Conclusions Tumor infiltrating mast cells are associated with worse prognosis in pancreatic cancer. In vitro, the interaction between mast cells and pancreatic cancer cells promote tumor growth and invasion.

Our results demonstrate that the flavonoid apigenin decreases glucose uptake and downregulates the GLUT-1 glucose transporter in human pancreatic cancer cells. In addition, the inhibitory effects of apigenin and the PI3K inhibitors on GLUT-1 are similar, indicating that the PI3K/Akt pathway is involved in mediating apigenin's effects on downstream targets such as GLUT-1.

Purpose: Arachidonic acid metabolism via the cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) pathways modulates cell growth and apoptosis. Many studies have examined the effects of COX inhibitors on human colorectal cancer, but the role of 5-LOX in colonic cancer development has not been well studied. The purpose of this study was to evaluate the expression of 5-LOX in colonic polyps and cancer and the effect of 5-LOX inhibition on colon cancer cell proliferation. Experimental Design: Colonic polyps, cancer, and normal mucosa were evaluated for 5-LOX expression by immunohistochemistry. Reverse transcription-PCR was used to establish 5-LOX expression in colon cancer cells. Thymidine incorporation and cell counts were used to determine the effect of the nonspecific LOX inhibitor Nordihydroguaiaretic Acid and the 5-LOX inhibitor Rev5901on DNA synthesis. A heterotopic xenograft model in athymic mice using HT29 and LoVo human colon cancer cells was used to evaluate the effect of the 5-LOX inhibitor zileuton on tumor growth. Results: 5-LOX is overexpressed in adenomatous polyps and cancer compared with that of normal colonic mucosa. LOX inhibition and 5-LOX inhibition decreased DNA synthesis in a concentration-and time-dependent manner in the Lovo cell line (P < 0.05). Inhibition of 5-LOX in an in vivo colon cancer xenograft model inhibited tumor growth compared with that of controls (P < 0.05).Conclusions: This study showed that 5-LOX is up-regulated in adenomatous colon polyps and cancer compared with normal colonic mucosa. The blockade of 5-LOX inhibits colon cancer cell proliferation both in vitro and in vivo and may prove a beneficial chemopreventive therapy in colon cancer.