Uteroglobin reverts the transformed phenotype in the endometrial adenocarcinoma cell line HEC-1A by disrupting the metabolic pathways generating platelet-activating factor

Uteroglobin, originally named blastokinin, is a protein synthesized and secreted by most epithelia, including the endometrium. Uteroglobin has strong anti-inflammatory properties that appear to be due, at least in part, to its inhibitory effect on the activity of the enzyme phospholipase A(2). In addition, recent experimental evidence indicates that uteroglobin exerts antiproliferative and antimetastatic effects in different cancer cells via a membrane receptor. The human endometrial adenocarcinoma cell line HEC-1A does not express uteroglobin. Thus, we transfected HEC-1A cells with human uteroglobin cDNA. The transfectants showed a markedly reduced proliferative potential as assessed by impaired plating efficiency as well as by reduced growth in soft agar. Cytofluorimetric analysis clearly indicated that in uteroglobin-transfected cells the time for completion of the cell cycle was increased. We previously demonstrated that HEC-1A cells actively synthesize platelet-activating factor, one of the products of phospholipase A(2) activity. In addition, we demonstrated that platelet-activating factor stimulates the proliferation of these cells through an autocrine loop. In uteroglobin transfectants, the activity of phospholipase A(2) and platelet-activating factor acetyl-transferase, which are involved in the synthesis of platelet-activating factor, was significantly reduced compared with wild-type and vector-transfected cells (p < 0.05). Our results indicate that enforced expression of uteroglobin in HEC-1A cells markedly reduced their growth potential and significantly impaired the synthesis of platelet-activating factor, an autocrine growth factor for these cells. These data suggest that one possible mechanism for the recently observed antineoplastic properties of uteroglobin may be the inhibition of the synthesis of platelet-activating factor.

Differential inhibitory effects on human endometrial carcinoma cell growth of luteinizing hormone-releasing hormone analogues

In addition to its function as a key hormone in the regulation of the pituitary-gonadal axis, luteinizing hormone-releasing hormone (LHRH) probably also affects various extrapituitary tissues. LHRH binding sites and in vitro antiproliferative effects of LHRH analogues have been reported in human endometrial cancer. The effects of the LHRH agonist leuproreline and LHRH antagonist antide were studied on the cell growth, DNA synthesis, and cell cycle distribution of the human endometrial cancer cell lines HEC-1A and HEC-1B by the sulforhodamine B (SRB) method, [3H]thymidine assay incorporation, and propidium iodide DNA staining, respectively. In the presence of 1.0-100 microM leuproreline the proliferation of HEC-1A cells was significantly reduced as early as 3 days after drug exposure, with a minimum growth value of 69.9 +/- 3.6% (mean +/- SE) at the highest concentration tested (100 microM). Similar antiproliferative effects were obtained following a 6-day treatment with the LHRH antagonist antide. Also, inhibitory effects on [3H]thymidine incorporation into the DNA of the HEC-1A cell line were noted after a 6-day exposure to both LHRH analogues, in the above-mentioned concentration range. Cell cycle analysis of HEC-1A cells cultured in the presence of 10 microM leuproreline and antide showed a slight accumulation of cells in the G0/G1 phase, while the proportions of cells in the S and G2/M phases concomitantly decreased. No significant effects on proliferation, DNA synthesis, and cell cycle distribution were observed in HEC-1B cells with either leuproreline or antide (up to 100 and 10 microM, respectively) after a 6-day exposure. Both Northern blot analysis and reverse transcription polymerase chain reaction failed to detect expression of mRNA for the LHRH receptor in both HEC-1A and HEC-1B cell lines. In addition, the LHRH analogues did not affect the intracellular free calcium concentration, indicating that the classic signal transduction for LHRH is absent or impaired in HEC-1A cells. The observed direct inhibitory actions on HEC-1A cells support the concept that the two LHRH analogues may exert biological effects via cellular effectors distinct from the "classic" LHRH receptor. Although the mechanism by which these direct actions are produced is still obscure, these results might help to establish the basis for new approaches to the therapy of endometrial cancer.

Flow cytometric analysis of DNA ploidy and cell proliferation activity in colorectal carcinoma

The aim of this study was to evaluate the relationship between DNA ploidy, proliferative activity and other prognostic factors and the survival of patients with colorectal cancer. 45 patients were prospectively investigated for 6 years. Fresh multiple samples for flow cytometric analysis of DNA content were collected during surgical resection of primary tumor. A 42% frequency of aneuploidy was observed with a median DNA index value of 1.54. The proliferative activity (%S+G2M cells) was higher in the aneuploid cell sub-population (28.6%) compared to the diploid counterpart (22.7%)(p = 0.05). No significant relationship between DNA ploidy and tumor site, Dukes' stage, histological type, grading age or sex was observed. No correlation between DNA ploidy and survival was demonstrated, including in the analysis of patient subsets according to stage. No additive prognostic information was obtained from a breakdown analysis as a function of DI values, percentages of aneuploid cells and proliferative activity. This study suggests that flow cytometric content analysis lacks prognostic value in colorectal carcinoma.

In vitro effects of brodimoprim on human polymorphonuclear leukocyte functions. Preliminary results

The in vitro effects of brodimoprim and trimethoprim on the functions of human polymorphonuclear (PMN) leukocytes have been studied comparatively evaluating chemotaxis, phagocytosis and production of superoxide anion. No significant effects of both diaminopyrimidines on chemotaxis and phagocytic activity of PMNs have been observed while both brodimoprim and trimethoprim enhanced the oxidative burst. A synergistic activity between the host immune system and the direct antimicrobial action of brodimoprim may occur while using this diaminopyrimidine in vivo.

Biochemical modulation of fluoropyrimidines by antifolates and folates in an in vitro model of human leukemia

Although 5-fluorouracil (FUra) is one of the most effective cytotoxic agents in the treatment of various solid tumors (carcinomas of the gastro-intestinal tract, breast, head and neck), remissions occur in only 20 to 30% of cases and usually are of short duration. Recently, preclinical studies have shown that the antitumor activity of FUra can be potentiated by modulating the metabolism of this drug by using other substances, in particular antifolates of folates. Pretreatment with antifolates may, by blocking de novo purine biosynthesis and consequently increasing phosphoribosyl pyrophosphate (PRPP) pools, enhance the conversion of FUra to active fluoronucleotide pools via orotate phosphoribosyltransferase. Methotrexate (MTX) pretreatment may also enhance binding of the fluoropyrimidine inhibitor, 5-fluodeoxyuridylate (FdUMP), to the target enzyme, thymidylate synthase (TS), indirectly by increasing dihydrofolate polyglutamates or directly, as MTX polyglutamates, by enhancing the formation of ternary complexes with FdUMP and TS. Exogenous folates, in particular 5-formyltetrahydrofolate (folinate, leucovorin, LV), can, by raising the intracellular levels of 5, 10-methylenetetrahydrofolate, lead to increased formation and stabilization of the ternary complex formed by TS, the folate coenzyme, and FdUMP. In vitro studies have also shown potentiation of FUra cytotoxicity by antifolates and folates against human lymphoblastic leukemia cell lines. Thus, while FUra may have little or no single agent activity in leukemias and lymphomas, it may be converted to an active drug in these neoplasms by appropriate modulation. Clinical studies of sequential MTX-FUra or combined LV-FUra based upon experimental tumor results reviewed herein, are warranted.