Human peritoneal fluid exerts ovulation- and nonovulation-sourced oncogenic activities on transforming fallopian tube epithelial cells

Secretory cells in the fallopian tube fimbria epithelium (FTE) are regarded as the main cells of origin of ovarian high-grade serous carcinoma (HGSC). Ovulation is the main cause of FTE oncogenesis, which proceeds through a sequence of TP53 mutations, chromosomal instability due to Rb/cyclin E aberration, in situ carcinoma (STIC), and metastasis to the ovary and peritoneum (metastatic HGSC). Previously, we have identified multiple oncogenic activities of the ovulatory follicular fluid (FF), which exerts the full spectrum of transforming activity on FTE cells at different stages of transformation. After ovulation, the FF is transfused into the peritoneal fluid (PF), in which the FTE constantly bathes. We wondered whether PF exerts the same spectrum of oncogenic activities as done by FF and whether these activities are derived from FF. By using a panel of FTE cell lines with p53 mutation (FT282-V), p53/CCNE1 aberrations (FT282-CCNE1), and p53/Rb aberrations plus spontaneous transformation, and peritoneal metastasis (FEXT2), we analyzed the changes of different transformation phenotypes after treating with FF and PF collected before or after ovulation. Similar to effects exhibited by FF, we found that, to a lesser extent, PF promoted anchorage-independent growth (AIG), migration, anoikis resistance, and peritoneal attachment in transforming FTE cells. The more transformed cells were typically more affected. Among the transforming activities exhibited by PF treatment, AIG, Matrigel invasion, and peritoneal attachment growth were higher with luteal-phase PF treatment than with the proliferative-phase PF treatment, suggesting an ovulation source. In contrast, changes in anoikis resistance and migration activities were similar in response to treatment with PF collected before and after ovulation, suggesting an ovulation-independent source. The overall transforming activity of luteal-phase PF was verified in an i.p. co-injection xenograft mouse model. Co-injection of Luc-FEXT2 cells with either FF or luteal-phase PF supported early peritoneal implantation, whereas co-injection with follicular-phase PF did not. This study, for the first time, demonstrates that PF from ovulating women can promote different oncogenic phenotypes in FTE cells at different stages of malignant transformation. Most of these activities, other than anoikis resistance and cell migration, are sourced from ovulation.

Choline Incorporation into Phospholipids in Mesothelial Cells in Vitro

Objective

To determine the effect of extracellular choline concentration on phospholipid production and handling by peritoneal mesothelial cells in vitro.

Design and Measurements

Radiolabeled choline was used to monitor the formation of phosphatidylcholine {PC), sphingomyelin (SPH), and Iysophosphatidylcholine (LPC) by rat and rabbit mesothelial cells as a function of concentration and time of exposure to choline. The subcellular location of the newly formed phospholipids was examined by ultracentrifugation in Percoll-sucrose gradients using analytical cell fractionation techniques. The fatty acid composition of the PC formed was determined by thin-layer chromatography (TLC) and gas chromatography.

Results

Choline incorporation into PC, SPH, and LPC increased with extracellular choline levels up to 640 μmol/L, which is 100 times greater than physiological levels of choline in plasma and 20 times higher than choline levels measured in peritoneal dialysis effluent. The newly formed, radiolabeled phospholipids were primarily found in a single subcellular compartment that exhibited a buoyant density of 1.05 g/mL in Percollsucrose gradients. Analysis of the fatty acyl groups of PC obtained from the mesothelial cells showed enrichment in palmitic [16:0], oleic [18:1], and linoleic [18:2] acids.

Conclusion

The rate of phospholipid formation by mesothelial cells in vitro can be manipulated, in part, by choline concentration.

The Biology of the Mesothelium during Peritoneal Dialysis

Substantial derangements of mesothelial biology are observed during experimental simulations of dialysis conditions, inferred from the content of human dialysis effluent and visualized by microscopy of human mesothelial biopsies. Canosmotically active solutions be made biocompatible with the osmoregulatory system of the mesothelium? Can the contributions of the mesothelium to host defenses against inflammation and/or infection be supported during CAPD? Do underlying metabolic derangements present in various kidney diseases and end-stage renal disease, regardless of cause, require customized CAPD protocols and solutions? Use of dialysis solutions less directly toxic to the mesothelium is a necessary step toward some day manipulating peritoneal biology by pharmacological and therapeutic modalities.

Lubrication of visceral movement and gastric motility by peritoneal surfactant

Four studies are described as a means of evaluating the hypothesis that surface-active phospholipid (SAPL) enhances the lubrication of gastric motility and visceral movement in general. In the first two studies, a lipid extract from ovine peritoneal rinsings was found to have remarkable antiwear capabilities ex vivo and to reduce friction to a remarkably low level as quantified by a coefficient of kinetic friction of 0.008 +/- 0.002 (n = 10). Moreover, this lipid extract demonstrated both these features of lubrication at high load. In other studies, peritoneal lipid extract was found to be highly surface-active, while many lamellar bodies (LB) have been identified in omentum and, by analogy with the lung and the stomach, would therefore appear to be a source of SAPL. Lubrication by peritoneal surfactant is discussed as another example of a ubiquitous barrier to abrasion and other potential insults common to all visceral surfaces.

A rapid high performance liquid chromatographic method for the analysis of choline in human plasma and peritoneal dialysis effluent: application in the assessment of choline loss in continuous ambulatory peritoneal dialysis

Mesothelial cells lining the peritoneal cavity utilize choline in the synthesis of a phosphatidylcholine-rich material thought to play a role in peritoneal homeostasis. This function is particularly important for patients undergoing continuous ambulatory peritoneal dialysis (CAPD). To assess choline loss in these patients, we measured choline in plasma and peritoneal dialysis effluent (PDE) by a rapid high performance liquid chromatography (HPLC) procedure that combined electrochemical detection with an immobilized enzyme reactor. Chromatography was performed directly on plasma and PDE ultrafiltrates. In 30 patients, the amount of choline lost to the dialysate was 129 +/- 49 mumol per day and 32 +/- 8 mumol per dwell (mean +/- SD). The average plasma choline concentration was 22.5 mumol/L, a value somewhat higher than the mean value reported for normal adults (9 mumol/L). The average PDE choline concentration was 14 mumol/L. There was a positive correlation between daily choline loss of dialysate and plasma choline concentrations (r = 0.826).