Properties and regulation of 17 beta-hydroxysteroid oxidoreductase of OVCAR-3, CAOV-3, and A431 cells: effects of epidermal growth factor, estradiol, and progesterone

MicroRNA-196a promotes cell proliferation and inhibits apoptosis in human ovarian cancer by directly targeting DDX3 and regulating the PTEN/PI3K/AKT signaling pathway

MicroRNAs (miRNAs/miRs) are small noncoding RNAs 19–24 nucleotides in length, which can play an important role in tumor development. However, the influence of miRNAs on the tumorigenicity of ovarian cancer cells has not been fully elucidated. Previously, DEAD box protein (DDX) 1 has been shown to play a role in tumor suppression of ovarian cancer progression. However, the functions of other DDX members in ovarian cancer development remain largely unknown. In the present study, it was demonstrated that overexpression of miR-196a promoted ovarian cancer cell proliferation. In addition, DDX3 was significantly downregulated in ovarian cancer cell lines relative to the normal ovarian cell line. Moreover, DDX3 was identified as a direct target of miR-196a in ovarian cancer cells. In addition, a preliminary mechanistic investigation indicated that downregulation of DDX3 promoted ovarian cancer cell proliferation through the PTEN/PI3K/AKT pathway. Taken together, this confirmed an association between DDX3 and miR-196a in ovarian cancer, and showed that miR-196a promoted the proliferation of ovarian cancer cells and attenuated apoptosis by downregulating the expression of DDX3 through the PTEN/PI3K/AKT pathway. Overall, the results of the present study suggested that DDX3 could be a novel target for ovarian cancer treatment.

17β-Estradiol Stimulates Generation of Reactive Species Oxygen and Nitric Oxide in Ovarian Adenocarcinoma Cells (OVCAR 3)

BACKGROUND

Experimental and epidemiological evidence supports a role for steroid hormones in the pathogenesis of ovarian cancer. Among steroid hormones, 17β-estradiol (E2) has the most potent effect on proliferation, apoptosis and metastasis.

OBJECTIVES

In the present study, we investigated the effect of E2 on production of ROS and NO in ovarian cancer cells.

MATERIALS AND METHODS

Ovarian adenocarcinoma cell line (OVCAR-3) was cultured and treated with various concentrations of E2, antioxidants (N-acetyle cysteine and Ebselen) and ICI182780 as an estrogen receptor antagonist. MTT test was performed to evaluate cell viability. NO and ROS levels were measured by Griess and DCFH-DA methods, respectively.

RESULTS

ROS levels as well as NO levels were increased in OVCAR-3 cells treated with E2. The increase in ROS production was in parallel with increased cell viability which indicates that estrogen-induced ROS can participate in cancer progression. ICI182780 abolished E2-induced ROS production. Progesterone was also effective in reducing ROS and NO generation.

CONCLUSIONS

NO and ROS are important molecules in signaling networks in cell. These molecules can be used as therapeutic targets for prevention and treatment of ovary cancer and other estrogen-induced malignancies.

A useful cell system for studying the regulation of 17HSD/KSR type 2 activity and expression in ovarian epithelial cancer

17β-Hydroxysteroid dehydrogenase/17-ketosteroid reductase (17HSD/KSR) activity and 17HSD/KSR types 1, 2, 4, and 5 mRNA levels were characterized in ovarian cancer cell lines derived from patients unexposed to radiation or chemotherapy. Activity was at the limit of detection in TOV-112D and TOV-21G cells. Activity in OV-90 was comparable to that in human placental tissue, was predominantly microsomal and was 17HSD/KSR type 2-like in substrate specificity and inhibition patterns. In monolayers, conversion of testosterone (T) to androstenedione (A) was 12-fold greater than that of A to T. Reduction of fetal bovine serum to 0.3% in the culture medium had no effect on 17β-HSD activity. Significant levels of type 1 and type 2 mRNAs were observed in OV-90 while only trace amounts were detected in TOV-21G. In contrast, type 4 mRNA levels were comparable for OV-90 and TOV-21G. Type 5 mRNA was detected in both cell lines but its level in OV-90 was twice that of TOV-21G. In OV-90, the type 2-like activity was predominant even though the type 5 mRNA level was 2.5-fold higher than that of the type 2. OV-90 cells may be a useful system for studying the regulation of 17HSD/KSR type 2 activity and expression in ovarian epithelial cancer.

Regulation of 17beta-hydroxysteroid dehydrogenase type 2, type 4 and type 5 by calcitriol, LXR agonist and 5alpha-dihydrotestosterone in human prostate cancer cells

Vitamin D seems to be involved in the control of prostate cancer cell growth. 17beta-Hydroxysteroid dehydrogenases type 2, type 4 and type 5 are enzymes which regulate intracellular concentration of active sex steroid hormones, which in turn, regulate the development, growth, and function of the prostate and play a role in the development and progression of prostate cancer. Using quantitative real-time PCR we find that calcitriol up-regulates HSD17B type 2, type 4 and type 5 in human prostate cancer LNCaP and PC3 cells but not in stromal cells. LXR agonist, TO-901317, suppresses the expression of HSD17B2 mRNA and inhibits calcitriol induced HSD17B2 expression. TO-901317 up-regulates the expression of HSD17B5 but not that of HSD17B4. 5alpha-Dihydrotestosterone up-regulates the expression of HSD17B2 and HSD17B4 but it significantly inhibits HSD17B5 expression by 70%. Calcitriol has no effect on DHT mediated expression of the three genes. The regulation of HSD17B2, HSD17B4 and HSD17B5 by ligands of LXR and VDR as well as AR in prostate cancer cells suggests a complex interaction of these signaling systems in the prostate.

Estrogens and epithelial ovarian cancer

OBJECTIVE

Molecular mechanisms involved in ovarian carcinogenesis are still unclear, but there is growing evidence that estrogens promote tumor progression in an epithelial ovarian cancer (EOC) subgroup.

METHODS

We reviewed current knowledge on the effects of estrogens in ovarian carcinogenesis and new potential research focuses concerning hormonal therapy of EOC.

RESULTS

Experimentally, estrogen stimulates the growth of ovarian tumor cell lines expressing estrogen receptors (ER). We and other authors have demonstrated differential expression of ERalpha or beta during ovarian carcinogenesis, with overexpression of ERalpha as compared to ERbeta in cancer. This differential expression in ER suggests that estrogen-induced proteins may act as ovarian tumor-promoting agents. Among these proteins, c-myc, fibulin-1, cathepsin-D, or several kallikreins may play a role, since high expression levels have been found in EOC. Consistently, recent prospective epidemiological studies have indicated that estrogen replacement therapy in postmenopausal women may increase ovarian cancer incidence and mortality.

CONCLUSION

Questions on the estrogen-sensitivity and potential benefits of new hormone therapies in an EOC subgroup should be readdressed in the light of recent experimental and clinical data.

Androgenic and estrogenic 17beta-hydroxysteroid dehydrogenase/17-ketosteroid reductase in human ovarian epithelial tumors: evidence for the type 1, 2 and 5 isoforms

17beta-Hydroxysteroid dehydrogenase/17-ketosteroid reductases (17HSD/KSR) play a key role in regulating steroid receptor occupancy in normal tissues and tumors. Although 17HSD/KSR activity has been detected in ovarian epithelial tumors, our understanding of which isoforms are present and their potential for steroid metabolism is limited. In this investigation, 17HSD/KSR activity from a series of ovarian epithelial tumors was assayed in cytosol and microsomes under conditions which differentiate between isoforms. Inhibition studies were used to further characterize the steroid specificities of isoforms in the two subcellular fractions. Activity varied widely between tumors of the same histopathologic classification. The highest levels of activity were observed in mucinous tumors. Michaelis constants, maximum velocities, estradiol-17beta/testosterone (E(2)/T) activity ratios and inhibition patterns were consistent with a predominance of microsomal 17HSD/KSR2 and cytosolic 17HSD/KSR5, isoforms reactive with both E(2) and T, with evidence of estrogenic 17HSD/KSR1 in cytosol from some samples. In tumors where activity and mRNA expression were both characterized, Northern blots, PCR and sequence analysis indicated 17HSD/KSR5 was the predominant isoform. The presence of 17HSD/KSR5, which also has both 3alpha-HSD/KSR and 20alphaHSD/KSR activity, and 17HSD/KSR2 which also has 20alpha-HSD activity, could influence not only estrogen and androgen binding but progesterone receptor occupancy, as well, in receptor-containing tumors.

Altered androgen metabolism eventually leads hepatocellular carcinoma to an impaired hormone responsiveness

Sex steroid hormones are thought, among several other risk factors, to play a role in liver malignancies. For example, from epidemiological studies in hepatocellular carcinoma (HCC), a clear disadvantage for male sex is evident. In addition, elevated levels of serum testosterone (T) and increased T to Estradiol (E(2)) ratio have been reported to predict an increased risk of HCC for male cirrhotic patients. On the other hand, palliative treatment of liver cancer patients with anti-hormones has been widely used in the past. However, the molecular mechanism(s) underlying sex steroid action on either normal or transformed liver cells, have not yet been fully clarified, nor endocrine discriminants have been satisfactorily assessed for an adequate characterization of liver cancer tissues. In this paper, we report studies on hormonal status of human liver tissues and cells, especially focusing on androgens, to better define endocrine end-points of interest for HCC. A consistent evidence from ex vivo or in vitro systems strongly suggests that high affinity binding sites of androgens are expressed at sufficient concentrations to induce a biological response in either normal or phenotipically transformed hepatocytes; in the latter, however, high heterogeneity and/or more scattering concentrations were encountered. Further, experimental data seem to suggest that lack of response to androgens may be due to a rapid metabolic conversion of steroids by neoplastic tissues and cells. Cancer hepatocytes privilege in fact 5beta more than 5alpha metabolic pathway of androgens. This may eventually lead biologically active androgens to be transformed into less active derivatives, as it occurs for T which is massively converted (>90% at 6 h) thus hindering the whole mechanism of action of androgens.

On the formation of steroidal amidoesters of 4-[N,N-bis(2-chloroethyl)amino]benzoic acid and their cytotoxic activity

The 4-[N,N-bis(2-chloroethyl)amino]benzoate of 17beta-acetamido-5alpha-androstan-3beta-ol, 17beta-acetamido-5-androsten-3beta-ol, 3beta-acetamido-5alpha-androstan-17beta-ol and 3alpha-acetamido-5beta-androstan-17beta-ol have been prepared and their antineoplastic effect evaluated against MIA Pa-Ca-2 pancreatic carcinoma, T47D breast carcinoma and A431 squamus cell carcinoma. Among the compounds tested, the compound 17beta-acetamido-3beta-hydroxy-5-androsten-4-[N, N-bis(2-chloroethyl)amino]benzoate appeared to possess a significant cytotoxic effect against A431 cells.

Expression of different 17beta-hydroxysteroid dehydrogenase types and their activities in human prostate cancer cells

The 17beta-hydroxysteroid dehydrogenase (17betaHSD) enzyme system governs important redox reactions at the C17 position of steroid hormones. Different 17betaHSD types (no. 1-4) have been identified to date in peripheral human tissues, such as placenta, testis, and breast. However, there is little information on their expression and activity in either normal or malignant prostate. In the present work, we have inspected pathways of 17beta-oxidation of either androgen or estrogen in human prostate cancer cells (LNCaP, DU145, and PC3) in relation to the expression of messenger RNAs (mRNAs) for 17betaHSD types 1-4. These cell systems feature distinct steroid receptor status and response to hormones. We report here that high expression levels of 17betaHSD4 were consistently observed in all three cell lines, whereas even greater amounts of 17betaHSD2 mRNA were detected solely in PC3 cells. Neither 17betaHSD1 nor 17betaHSD3 mRNAs could be detected in any cell line. From a metabolic standpoint, intact cell analysis showed a much lower extent of 17beta-oxidation of both androgen [testosterone (T)] and estrogen [estradiol (E2)] in LNCaP and DU145 cells compared to PC3 cells, where a greater precursor degradation and higher formation rates of oxidized derivatives (respectively, androstenedione and estrone) were observed. Using subcellular fractionation, we have been able to differentiate among 17betaHSD types 1-4 on the basis of their distinct substrate specificities and subcellular localization. This latter approach gave rise to equivalent results. PC3 cells, in fact, displayed a high level of microsomal activity with a low E2/T activity ratio and approximately equal apparent Km values for E2 and T, suggesting the presence of 17betaHSD2. Dehydrogenase specific activity with both E2 and T was also detected, although at lower levels, in LNCaP and DU145 cells. No evidence for reductase activity could be obtained in either the soluble or microsomal fraction of any cell line. As comparable expression levels of 17betaHSD4 were seen in the three cell lines, 17betaHSD2 is a likely candidate to account for the predominant oxidative activity in PC3 cells, whereas 17betaHSD4 may account for the lower extent of E2 oxidation seen in both LNCaP and DU145 cells. This is the first report on the expression of four different 17betaHSD types in human prostate cancer cells. It ought to be emphasized that for the first time, analysis of different 17betaHSD activities in either intact or fractionated cells harmonizes with the expression of relevant mRNAs species.