Morphoproteomic analysis reveals an overexpressed and constitutively activated phospholipase D1-mTORC2 pathway in endometrial carcinoma.

The mammalian target of rapamycin (MTOR) assembles into two distinct complexes: mTOR complex 1 (mTORC1) is predominantly cytoplasmic and highly responsive to rapamycin, whereas mTOR complex 2 (mTORC2) is both cytoplasmic and nuclear, and relatively resistant to rapamycin. mTORC1 and mTORC2 phosphorylatively regulate their respective downstream effectors p70S6K/4EBP1, and Akt. The resulting activated mTOR pathways stimulate protein synthesis, cellular proliferation, and cell survival. Moreover, phospholipase D (PLD) and its product, phosphatidic acid (PA) have been implicated as one of the upstream activators of mTOR signaling. In this study, we investigated the activation status as well as the subcellular distribution of mTOR, and its upstream regulators and downstream effectors in endometrial carcinomas (ECa) and non-neoplastic endometrial control tissue. Our data show that the mTORC2 activity is selectively elevated in endometrial cancers as evidenced by a predominant nuclear localization of the activated form of mTOR (p-mTOR at Ser2448) in malignant epithelium, accompanied by overexpression of nuclear p-Akt (Ser473), as well as overexpression of vascular endothelial growth factor (VEGF)-A isoform, the latter a resultant of target gene activation by mTORC2 signaling via hypoxia-inducible factor (HIF)-2alpha. In addition, expression of PLD1, one of the two major isoforms of PLD in human, is increased in tumor epithelium. In summary, we demonstrate that the PLD1/PA-mTORC2 signal pathway is overactivated in endometrial carcinomas. This suggests that the rapamycin-insensitive mTORC2 pathway plays a major role in endometrial tumorigenesis and that therapies designed to target the phospholipase D pathway and components of the mTORC2 pathway should be efficacious against ECa.

{\it In vivo\/} magnetic resonance studies of experimental liver disease: Carbon tetrachloride hepatotoxicity and alcohol-induced fatty liver in rat

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) were used to non-invasively determine if cirrhosis induced by carbon tetrachloride (CCl$\sb4$) and phospholipase-D (PLD) could be distinguished from fatty infiltration in rat. MRS localization and water suppression methods were developed, implemented and evaluated in terms of their application to in vivo proton NMR studies of experimental liver disease. MRS studies were also performed to quantitate fatty infiltration resulting from carbon tetrachloride (CCl$\sb4$) or alcohol (ethanol) administration and the MRS results were confirmed using biochemical total lipid analysis and histology. $\rm T\sb1$ weighted MR images acquired weekly, 48 hours post administration, demonstrated only a slight increase in overall liver intensity with CCl$\sb4$ or alcohol administration, which is consistent with previously reported results. The MR images were able to detect nodules resulting from CCl$\sb4$+PLD induced cirrhosis as hypointense regions, also consistent with previous reports. Localized in vivo water and lipid proton $\rm T\sb1$ relaxation time measurements were performed and demonstrated no statistically significant trends for either agent. In vivo proton spectra were also acquired using stimulated echo techniques to quantitatively follow the changes in liver lipid content. The changes in liver lipid content observed using MRS were verified by total lipid analysis using the Folch technique and histology. The in vivo $\rm T\sb1$ and lipid quantification data str inconsistent with the previous hypothesis that the changes in $\rm T\sb1$ weighted images were the result of increased "free" water content and, therefore, increased water $\rm T\sb1$ relaxation times. These data indicate that the long term changes are more likely the result of changes in lipid content. The data are also shown to agree with the accepted hypothesis that the time course and mechanism of fatty infiltration are different for CCl$\sb4$ and alcohol. The hypothesis that the lipids resulting from either protocol are from the same lipid fraction(s), presumably triglycerides, is also supported. And lastly, on the basis of MR images and quantitative MRS lipid information, it was shown that cirrhosis could be distinguished from fatty infiltration. ^

Assessment of cone beam computed tomography techniques for imaging lung damage in mice in vivo

Lung damage is a common side effect of chemotherapeutic drugs such as bleomycin. This study used a bleomycin mouse model which simulates the lung damage observed in humans. Noninvasive, in vivo cone-beam computed tomography (CBCT) was used to visualize and quantify fibrotic and inflammatory damage over the entire lung volume of mice. Bleomycin was used to induce pulmonary damage in vivo and the results from two CBCT systems, a micro-CT and flat panel CT (fpCT), were compared to histologic measurements, the standard method of murine lung damage quantification. Twenty C57BL/6 mice were given either 3 U/kg of bleomycin or saline intratracheally. The mice were scanned at baseline, before the administration of bleomycin, and then 10, 14, and 21 days afterward. At each time point, a subset of mice was sacrificed for histologic analysis. The resulting CT images were used to assess lung volume. Percent lung damage (PLD) was calculated for each mouse on both the fpCT (PLDfpcT) and the micro-CT (PLDμCT). Histologic PLD (PLDH) was calculated for each histologic section at each time point (day 10, n = 4; day 14, n = 4; day 21, n = 5; control group, n = 5). A linear regression was applied to the PLDfpCT vs. PLDH, PLDμCT vs. PLDH and PLDfpCT vs. PLDμCT distributions. This study did not demonstrate strong correlations between PLDCT and PLDH. The coefficient of determination, R, was 0.68 for PLDμCT vs. PLDH and 0.75 for the PLD fpCT vs. PLDH. The experimental issues identified from this study were: (1) inconsistent inflation of the lungs from scan to scan, (2) variable distribution of damage (one histologic section not representative of overall lung damage), (3) control mice not scanned with each group of bleomycin mice, (4) two CT systems caused long anesthesia time for the mice, and (5) respiratory gating did not hold the volume of lung constant throughout the scan. Addressing these issues might allow for further improvement of the correlation between PLDCT and PLDH. ^