Rac1-GTPase activation plays a key role in the development and progression of cardiac remodeling. Therefore, we engineered a transgenic mouse model by overexpressing cDNA of a constitutively active form of Zea maize Rac gene (ZmRacD) specifically in the hearts of FVB/N mice. Echocardiography and MRI analyses showed cardiac hypertrophy in old transgenic mice, as evidenced by increased left ventricular (LV) mass and LV mass-to-body weight ratio, which are associated with relative ventricular chamber dilation and systolic dysfunction. LV hypertrophy in the hearts of old transgenic mice was further confirmed by an increased heart weight-to-body weight ratio and histopathology analysis. The cardiac remodeling in old transgenic mice was coupled with increased myocardial Rac-GTPase activity (372%) and ROS production (462%). There were also increases in α(1)-integrin (224%) and β(1)-integrin (240%) expression. This led to the activation of hypertrophic signaling pathways, e.g., ERK1/2 (295%) and JNK (223%). Pravastatin treatment led to inhibition of Rac-GTPase activity and integrin signaling. Interestingly, activation of ZmRacD expression with thyroxin led to cardiac dilation and systolic dysfunction in adult transgenic mice within 2 wk. In conclusion, this is the first study to show the conservation of Rho/Rac proteins between plant and animal kingdoms in vivo. Additionally, ZmRacD is a novel transgenic model that gradually develops a cardiac phenotype with aging. Furthermore, the shift from cardiac hypertrophy to dilated hearts via thyroxin treatment will provide us with an excellent system to study the temporal changes in cardiac signaling from adaptive to maladaptive hypertrophy and heart failure.

Prolonged exposure to unopposed estrogens is a major risk factor for the development of endometrial cancer. Oxidative metabolism of estradiol (E 2 ) into the catecholestrogens (CEs), 4-hydroxyestradiol (4-OHE 2 ) and 2-hydroxyestradiol (2-OHE 2 ), may play an important role in estrogen carcinogenicity. CEs can be oxidized to the corresponding ortho-quinone derivatives with concomitant formation of the reactive oxygen species (ROS). Catechol-O-methyltransferase (COMT) is the major enzyme involved in the detoxification of CEs in extrahepatic tissues. We investigated the potential of E 2 , 2-OHE 2 and 4-OHE 2 to induce microsatellite instability (MSI) and neoplastic transformation of immortalized human endometrial glandular (EM) cells. We also investigated the functional significance of COMT gene expression on modulating the effects of E 2 and CEs in EM cells. Our data indicated that E 2 and 4-OHE 2 induce MSI, ROS and neoplastic transformation in EM cells. The capacity of E 2 and its catechol metabolites to induce MSI, ROS and neoplastic transformation in EM cells is ranked as follows: 4-OHE 2 > E 2 > 2-OHE 2 . Knockdown of COMT expression in EM cells resulted in increased estrogenic milieu and increased estrogen-induced cell proliferation. More importantly, knockdown of COMT increased the propensity of E 2 or CEs to induce ROS, MSI and neoplastic transformation of EM cells. In contrast, overexpression of COMT in EM cells significantly reduced the cellular estrogenic milieu and protected against E 2 -or CEs-induced, ROS, MSI and neoplastic transformation. The capacity of E 2 or CEs to induce neoplastic transformation of human endometrial glandular cells in vitro may suggest that E 2 -induced endometrial cancer is mediated by its metabolism into CEs. Our study clearly indicates that COMT gene expression plays a critical role in modulating the hormonal and carcinogenic effects of E 2 and CEs and, consequently, modifies the risk for E 2 -induced endometrial cancer. To the best of our knowledge, this is the first study to (i) demonstrate the potential capacity of estrogen and its catechol metabolites to induce neoplastic transformation of immortalized human endometrial glandular cells; and (ii) illustrate the important role of COMT gene expression in protecting against E 2 -induced endometrial cancer. ' 2008 Wiley-Liss, Inc. Key words: catecholestrogens;COMT; genomic instability; endometrial cancer Endometrial cancer is the most common cancer of the genital tract in American women and ranks first in incidence and second in mortality among gynecological malignancies. 1 It is estimated that the rates of endometrial cancer in American women are among the highest in the world. 2 The risk factors for endometrial cancer include nulliparity, early age at menarche, late age at menopause, obesity and long-term use of estrogen replacement therapy (ERT). These risk factors seem to relate, either directly or indirectly, prolonged exposure to an unopposed estrogen. 3 Most endometrial carcinomas are Type I estrogen-associated endo...

Increased mechanical stress/hypertension in the vessel wall triggers the hypertrophic signaling pathway, resulting in structural remodeling of vasculature. Vascular hypertrophy of resistance vessels leads to reduced compliance and elevation of blood pressure. We showed before that increased expression of profilin1 protein in the medial layer of the aorta induces stress fiber formation, triggering the hypertrophic signaling resulting in vascular hypertrophy and, ultimately, hypertension in older mice. Our hypothesis is that profilin1 induced vascular hypertrophy in resistance vessels, which led to elevation of blood pressure, both of which contributed to the modulation of vascular function. Our results showed significant increases in the expression of alpha(1)- and beta(1)-integrins (280 + or - 6.3 and 325 + or - 7.4%, respectively) and the activation of the Rho/Rho-associated kinase (ROCK) II pathway (260 and 350%, respectively, P < 0.05) in profilin1 mesenteric arteries. The activation of Rho/ROCK led to the inhibition of endothelial nitric oxide synthase expression (39 + or - 5.4%; P < 0.05) and phosphorylation (35 + or - 4.5%; P < 0.05) but also an increase in myosin light chain 20 phosphorylation (372%, P < 0.05). There were also increases in hypertrophic signaling pathways in the mesenteric arteries of profilin1 mice such as phospho-extracellular signal-regulated kinase 1/2 and phospho-c-Jun NH(2)-terminal kinase (312.15 and 232.5%, respectively, P < 0.05). Functional analyses of mesenteric arteries toward the vasoactive drugs were assessed using wire-myograph and showed significant increases in the vascular responses of profilin1 mesenteric arteries toward phenylephrine, but significant decreases in response toward ROCK inhibitor Y-27632, ACh, sodium nitrite, and cytochalasin D. The changes in vascular responses in the mesenteric arteries of profilin1 mice are due to vascular hypertrophy and the elevation of blood pressure in the profilin1 transgenic mice.

Histone deacetylase 6 (HDAC6) is an attractive target for cancer therapeutic intervention. Selective HDAC6 inhibitors is important to minimise the side effects of pan inhibition. Thus, new class of hydroxamic acid-based derivatives were designed on structural basis to perform preferential activity against HDAC6 targeting solid tumours. Interestingly, 1-benzylbenzimidazole-2-thio- N -hydroxybutanamide 10a showed impressive preference with submicromolar potency against HDAC6 (IC 50 = 510 nM). 10a showed cytotoxic activity with interesting profile against CCHE-45 at (IC 50 = 112.76 µM) when compared to standard inhibitor Tubacin (IC 50 = 20 µM). Western blot analysis of acetylated-α-tubulin verified the HDAC6 inhibiting activity of 10a . Moreover, the insignificant difference in acetylated-α-tubulin induced by 10a and Tubacin implied the on-target cytotoxic activity of 10a . Docking of 10a in the binding site of HDAC6 attributed the activity of 10a to π-π stacking with the amino acids of the hydrophobic channel of HDAC6 and capture of zinc metal in bidentate fashion. The therapeutic usefulness besides the on-target activity may define 10a as an interesting safe-lead inhibitor for future development.