Prostaglandin E2 and cyclic AMP in tumor and plasma of breast cancer patients

Multi-Omics Approach Points to the Importance of Oxylipins Metabolism in Early-Stage Breast Cancer

The involvement of oxylipins, metabolites of polyunsaturated fatty acids, in cancer pathogenesis was known long ago, but only the development of the high-throughput methods get the opportunity to study oxylipins on a system level. The study aimed to elucidate alterations in oxylipin metabolism as characteristics of breast cancer patients. We compared the ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) oxylipin profile signatures in the blood plasma of 152 healthy volunteers (HC) and 169 patients with different stages of breast cancer (BC). To integrate lipidomics, transcriptomics, and genomics data, we analyzed a transcriptome of 10 open database datasets obtained from tissues and blood cells of BC patients and SNP data for 33 genes related to oxylipin metabolism. We identified 18 oxylipins, metabolites of omega-3 or omega-6 polyunsaturated fatty acids, that were differentially expressed between BCvsHC patients, including anandamide, prostaglandins and hydroxydocosahexaenoic acids. DEGs analysis of tissue and blood samples from BC patients revealed that 19 genes for oxylipin biosynthesis change their expression level, with CYP2C19, PTGS2, HPGD, and FAAH included in the list of DEGs in the analysis of transcriptomes and the list of SNPs associated with BC. Results allow us to suppose that oxylipin signatures reflect the organism's level of response to the disease. Our data regarding changes in oxylipins at the system level show that oxylipin profiles can be used to evaluate the early stages of breast cancer.

Prostaglandin E2 Reverses the Effects of DNA Methyltransferase Inhibitor and TGFB1 on the Conversion of Naive T Cells to iTregs

Naturally occurring regulatory T cells (nTregs) are produced under thymic (tTregs) or peripherally induced (pTregs) conditions in vivo. On the other hand, Tregs generated from naive T cells in vitro under some circumstances, such as treatment with transforming growth factor-β (TGFB), are called induced Tregs (iTregs). Tregs are especially characterized by FOXP3 expression, which is mainly controlled by DNA methylation. nTregs play important roles in the suppression of immune response and self-tolerance. The prostaglandin E2 (PGE2) pathway was reported to contribute to regulatory functions of tumor-infiltrating nTregs. In this study, we examined whether PGE2 contributes to the formation of iTregs treated with TGFB1 and 5-aza-2'-deoxycytidine (5-aza-dC), which is a DNA methyltransferase inhibitor. We found that the protein and gene expression levels of FOXP3 and IL-10 were increased in 5-aza-dC and TGFB1-treated T cells in vitro. However, the addition of PGE2 to these cells reversed these increments significantly. In CFSE-based cell suppression assays, we demonstrated that PGE2 decreased the suppressive functions of 5-aza-dC and TGFB1-treated T cells.

Cyclooxygenase-2 169C>G and 8473T>C gene polymorphisms and prostaglandin E2 level in breast cancer: a case-control study

AIMS

Cyclooxygenase 2 (COX-2) with the resulting prostaglandin E2 (PGE2) is linked to increased risk of human breast cancer (BC). The aim of this study was to determine COX-2 169C>G and 8473T>C gene polymorphisms and PGE2 level at various stages of BC clarifying the role of COX-2 gene polymorphism and PGE2 in relation to BC.

METHODS

The study population comprised 160 women at different stages of BC and 150 gender- and age-matched healthy control subjects. Plasma PGE2 was measured by ELISA, the COX-2 gene polymorphisms were determined using PCR-RFLP.

RESULTS

The variant alleles COX-2 169G and 8473C were significantly associated with BC susceptibility [OR=3.1, 95% CI (2.2-4.4), P<0.001 for 169C>G and OR=1.74, 95%CI (1.3-2.4), P=0.005 for 8473C]. However, both COX-2 gene polymorphisms were not associated with breast cancer stage. Plasma PGE2 levels were significantly increased in patients compared to the controls. In early and late stages of BC, there was a significant increase in the plasma PGE2 levels towards the presence of homozygous GG compared with homozygous CC (P<0.001) for 169 C>G, also towards the presence of CC than TT (P<0.001) for 8473T>C SNP.

CONCLUSION

The 169C>G and 8473T>C polymorphisms of the COX-2 gene were associated with the BC in Egyptian women. Furthermore, individuals with COX-2 169GG and 8473CC genotypes showed significant increase in plasma PGE2 levels. PGE2 levels may serve as a predictor of poor prognosis in patients with BC.

Association between NSAIDs use and breast cancer risk: a systematic review and meta-analysis

The association between non-steroidal anti-inflammatory drugs (NSAIDs) use and breast cancer has remained controversial. Therefore, an overall quantitative estimate of the association needs to be studied. A systematic review and meta-analysis was executed to explore the pooled estimate for relative risk (RR) and 95% confidence interval (CI) using random or fixed effects models based on heterogeneity analysis. Overall 26 studies with 528,705 participants were included. The RR of NSAIDs use and the incidence of breast cancer was 0.94 (95% CI: 0.88-1.00) with random effects model. A slight reduction of breast cancer by taking aspirin and ibuprofen was both observed with pooled RR of 0.91 (95% CI: 0.83-0.98) and 0.81 (95% CI: 0.67-0.97), respectively. Our results indicate that NSAIDs use is associated with a slight decrease for the development of breast cancer with a marginally statistical significant difference. The associations are slightly more obvious in aspirin and ibuprofen use.

Inverse correlation between serum PGE2 and T classification in head and neck cancer

BACKGROUND

Prostaglandin E2 (PGE2) serum levels have been shown previously to be increased in tumor bearing mice as well as in patients with solid tumors; however, the impact on the course or stage of disease has not been shown. We hypothesized that PGE2 is strictly required for aggressive and especially early-stage tumors of the head and neck to provoke invasion and angiogenesis.

METHODS

We analyzed the serum PGE2 levels of 100 patients with head and neck squamous cell carcinoma of different stages before and 1 year after treatment and compared the results with the serum levels of 40 healthy donors and the secretion profile of 8 different squamous cell carcinoma cell lines.

RESULTS

Our investigations showed a statistically significant inverse correlation between PGE2 serum levels and tumor stage. Furthermore, this effect has been reflected by the results of our cell culture analyses, which showed an inversely regulated PGE2 secretion into the medium during the process of proliferation. Interestingly, the serum levels of PGE2 were significantly downregulated 1 year after successful treatment.

CONCLUSIONS

We conclude that PGE2 serum level as an indicator for early-stage cancer of the head and neck may function as a tumor marker during the follow-up period.

Prostaglandin E2 levels and lymphocyte subsets in portal venous drainage of colorectal cancers

Local immunosurveillance may play an important role in the growth and spread of tumors. To investigate the local immune response, we determined prostaglandin E2 (PGE2) levels (n = 23) and lymphocyte subsets (n = 10) in the portal vein draining the tumors of patients with colorectal cancer. PGE2 levels in the portal vein were significantly higher than those in the radial artery. Portal PGE2 levels in patients with advanced stage tumors (Duke's C and D) and lymph node metastases were significantly higher than those of patients with Duke's A and B tumors without lymph node metastases. Moreover, four of the nine patients with portal PGE2 levels greater than 100 pg/mL had liver metastases within 2 years of surgery. There were no differences in lymphocyte subsets between the portal vein and the radial artery. PGE2 levels in the portal vein draining colorectal tumor may thus be closely related to tumor progression and recurrence and may serve as a predictor of tumor recurrence in patients with colorectal cancer.

Acetylsalicylic acid (ASA) protects the prostaglandin-cAMP-system of human hypernephroma cells against irradiation-induced alterations

There is abundant evidence that inhibitors of prostaglandin (PG) biosynthesis might increase the radioresponse of certain tumour cells. This study investigated specific PG binding sites, eicosanoid production as well as intracellular cAMP levels in cultured human hypernephroma cells derived from 11 patients upon nephrectomy. Scatchard analyses of the binding data revealed specific PGE1-, PGE2- as well as PGI2-binding sites (PGE1: Bmax = 755 +/- 206 fmol mg-1 protein, Kd = 3.7 +/- 2.7 nM PGE2: Bmax = 494 +/- 221 fmol mg-1 protein, Kd = 4.2 +/- 2.5 nM; PGI2: Bmax = 693 +/- 164 fmol mg-1 protein, Kd = 6.0 +/- 4.5 nM). Significant (P < 0.01) increase in PG binding sites expressed on human hypernephroma cells (PGE1: Bmax = 1084 +/- 303 fmol mg-1 protein, Kd = 2.8 +/- 1.3 nM; PGE2: Bmax = 663 +/- 309 fmol mg-1 protein, Kd = 2.2 +/- 1.5 nM; PGI2: Bmax = 1021 +/- 391 fmol/protein, Kd = 4.2 +/- 3.6 nM) and inhibition of PG biosynthesis (TXB2: -82.5%, PGE2: -87.5%. PGD2: -80.6%, PGF2: -81.3%) were found after acetylsalicylic acid (ASA)-treatment (0.5 mg 10(-6) cells for 24 h). Following irradiation (60Co, 1.0 Gy/min-1 over 10(min), PG binding sites (PGE1: Bmax = 266 +/- 153 fmol mg-1 protein, Kd = 5.0 +/- 5.0 nM; PGE2: Bmax = 148 +/- 66 fmol mg-1 protein, Kd = 4.7 +/- 3.6 nM; PGI2: Bmax = 325 +/- 194 fmol mg-1 protein, Kd = 6.8 +/- 7.1 nM) were significantly (P < 0.01) diminished. However, irradiation had no significant effect on PG binding sites in ASA-pretreated cells (PGE1: Bmax = 699 +/- 240 fmol mg-1 protein, Kd = 3.5 +/- 1.8 nM; iloprost: Bmax = 766 +/- 452 fmol mg-1 protein, Kd = 3.2 +/- 2.2 nM). Although there was no significant difference in the basal values for cAMP between control and ASA-treated group cells, the PG-induced cAMP-production was less pronounced in the control group. Taken together, the findings suggest that ASA may modify the radioresponse of cultured human hypernephroma cells by preventing the decrease of PG binding sites induced by irradiation.

Clinical significance of prostacyclin and thromboxane in cancer of the female breast and genital tract

Studies investigating the role of thromboxane A2 and prostacyclin in cancer of the female breast and genital tract are reviewed. Whereas thromboxane A2 was found to promote the tumour growth and metastasis, prostacyclin exerted a protective effect in maintaining vascular and platelet homeostasis. Thus, monitoring of prostacyclin and thromboxane levels in plasma and urine of cancer patients may be essential for the evaluation of tumour growth and metastasis. Of all modulators of thromboxane and prostacyclin biosynthesis, nafazatrom was found to exhibit promising results for the treatment of advanced breast cancer, although its use in the routine therapy is questionable at this stage.

Prognostic significance of plasma prostaglandin E concentration in patients with head and neck cancer

Plasma prostaglandin E (PGE) levels were determined by radioimmunoassay in 53 patients with various stages (II, III, and IV) of hypopharyngeal and laryngeal squamous cell carcinoma, in 12 non-cancer patients and in 10 healthy volunteers. The mean PGE concentration was somewhat higher in non-cancer patients (mean +/- SD = 34.6 +/- 5.37 pg/ml) than in healthy subjects (28.1 +/- 4.96 pg/ml). In spite of a high data variability, the mean preoperative PGE levels in cancer patients were proportional to the stage of the disease and higher than in non-cancer patients (41.2 +/- 19.7 pg/ml, 52.8 +/- 26.7 pg/ml and 82.0 +/- 34.9 pg/ml in stages II, III and IV respectively). The mean plasma PGE concentration significantly decreased for all tumour stages 15-30 days after surgical removal of the tumour, but rose again in some patients within 6-18 months after surgery. The incidence of tumour recurrences 6 and 18 months after surgery was significantly higher in patients with an increased preoperative PGE level (greater than 43.3 pg/ml) than in those patients with a PGE level within the normal range (less than 43.3 pg/ml). The mortality was also higher in the former group, but the difference did not reach the level of significance. Similarly, the mean preoperative and most postoperative concentrations of PGE were significantly higher in patients in whom tumour recurred within 18 months than in tumour-free patients.

Production of prostaglandin E by squamous carcinoma of the head and neck and adenocarcinoma of gastrointestinal tissue

The production of prostaglandin E ex vivo was studied in samples of 31 squamous cell carcinomas of the head and neck (SCCHN) and 12 adenocarcinomas of gastrointestinal tract (ACGI). As a control, the PGE production was measured in 22 samples of noninvolved mucosa in patients with SCCHN and 12 samples of gastrointestinal mucosas. The mean PGE production by SCCHN was significantly higher than in normal mucosa. Furthermore, the PGE production by tumors which recurred or spread to regional lymph node within 18 months after surgery was higher than in tumors which did not recur within that interval. Also, production of PGE by noninvolved mucosa was significantly higher in patients in which tumor recurred after surgery than in patients which were tumor free. On the other hand, the mean production of PGE by ACGI was not different from that of normal mucosa. These data show that determination of PGE production might have prognostic significance in SCCHN.

Prognostic value of prostaglandin F2 alpha concentrations in breast carcinoma

Prostaglandin F2 alpha (PGF2 alpha) concentrations were measured by radioimmunoassay in homogenised primary tumours from 57 patients with breast cancer. These patients were followed up from 60 to 78 months (median 63 months) after surgery and PGF2 alpha concentrations were related prospectively to metastatic spread and survival. The amounts of PGF2 alpha varied greatly in the different tumours (range 0-90 ng/mg protein), but no significant association was found between PGF2 alpha concentrations and disease free survival, time of relapse, site of recurrence, or overall survival. It therefore seems unlikely that measurement of PGF2 alpha in breast carcinoma is important in the prognosis of the disease.

Prostacyclin and thromboxane in benign and malignant breast tumours

6-keto-PGF1 alpha and thromboxane B2 were determined by radioimmunoassay in 37 extracts of breast carcinomata, 8 fibroadenomata, 12 sclerocystic-disease specimens and 51 normal breast tissues. More prostanoids were extracted from carcinomata than from normal specimens, fibroadenomata or sclerocystic-disease tissues (P less than 0.05). The 6-keto-PGF1 alpha/TXB2 ratio was higher in carcinomata than in normal tissues and fibroadenomata (P less than 0.05) but was not significantly different from the ratio in sclerocystic disease. The prostaglandin levels and the 6-keto-PGF1 alpha/TXB2 ratios from carcinomata did not correlate significantly with age, tumour size, differentiation, lymph node status, nuclear-cytoplasmic ratio, host cell reaction, mast cells, necrosis, elastosis, fibrosis or blood vessel density. Lower nuclear density was associated with lower 6-keto-PGF1 alpha/TXB2 ratios (P = 0.01) whereas the latter value was higher when infiltration was lower (P = 0.03). There was a positive correlation between mitotic index and the 6-keto-PGF1 alpha/TXB2 ratio (P = 0.04). Cumulation of variables revealed lower prostanoid ratios in tumours greater than 2 cm without lymph node metastasis then tumours less than 2 cm with lymph node metastasis (P = 0.04). A first follow-up (14 months) showed a higher 6-keto-PGF1 alpha/TXB2 ratio in patients who developed metastasis (P = 0.04). Our study does not confirm the hypothesis that high prostacyclin levels are a good prognostic index in breast cancer.

Biological half-life of prostacyclin and 6-oxo-PGF1 alpha levels in plasma of patients with colonic cancer

Prostaglandins have been shown to play a central role in the formation of cancer. The synthesis of prostacyclin and its bioavailability may be an important local determinant for metastasis. As the amount of the biologically active substance is dependent in part on the half-life (T/2) we examined the question as to whether the T/2 of prostaglandin I2 (PGI2) is altered in patients suffering from colonic cancer at various stages of the disease. In addition, the influence of various therapeutic regimens was investigated. In 58 patients with various stages of colonic cancer no significant difference in PGI2-T/2 could be detected. No significant difference could be found before (10, 11 +/- 1, 9 min) and after (10, 03 +/- 1, 8 min) tumor resection, before (9, 89 +/- 1, 5 min) and after 10, 35 +/- 1,8 min) chemotherapy, before (10, 36 +/- 1, 5 min) and after (10, 89 +/- 2, 31 min) irradiation as well as before (8, 86 +/- 1, 9 min) and after (9, 07 +/- 1, 2 min) tumor resection at least 4 to 6 years ago. In 14 healthy people PGI2-T/2 (10, 05 +/- 2, 1 min) did not differ significantly. In all the 58 patients the plasma levels of 6-oxo-PGF1 alpha, the stable derivative of PGI2 were measured. As compared to healthy controls (less than 1 pg/ml) the actual 6-oxo-PGF1 alpha values of patients with colonic cancer were significantly increased. However, no correlation to the T/2 of PGI2 (r between 0, 03 and 0, 21, n.s.) in plasma in vitro could be discovered. After curative tumor resection and after chemotherapy the plasma levels of 6-oxo-PGF1 alpha were significantly lower than before. The data suggest that in patients suffering from colonic cancer the speed of degradation of PGI2 is not a key determinant in local hemostatic dysregulation favouring early metastasis. However, PGI2 or its stable derivatives may be involved in the development of colonic cancer.

Prostaglandin E2 and cyclic nucleotides in plasma and urine of colonic cancer patients

Prostaglandin E2 and cyclic nucleotide levels were measured in plasma and urine of 14 patients with colonic cancer. The measurements were performed 1 day before and 8 days after the removal of the tumor by operation. There was no difference between the plasma PGE2 levels (in form of the 13, 14-dihydro-15-keto metabolite) before and after the operation, but they were significantly higher than the level of a control group. No differences before and after operation were found between plasma cyclic AMP (cAMP) levels, plasma cyclic GMP (cGMP) levels, urinary cAMP levels and urinary cGMP levels. All the cyclic nucleotide concentrations were within the normal range. No correlation could be found between the stage of the tumor spread and any of the substances analyzed. The conclusions are that plasma PGE2 and plasma and urinary cyclic nucleotides do not originate from the colonic tumor tissue, and that these substances cannot be used as tumor markers.

Prostaglandin F2 alpha in benign and malignant breast tumours

Prostaglandin F2 alpha (PGF2 alpha) was determined by radioimmunoassay in 57 breast carcinomata, 16 fibroadenomata, and 33 sclero-cystic-disease (SCD) specimens. In 41 cases of carcinoma and 10 cases of fibroadenoma, histologically non-malignant tissue was also obtained from the same breast. PGF2 alpha levels were significantly elevated in breast cancer when compared with the normal tissues and benign diseases (P less than 0.005 for each group). High PGF2 alpha levels were positively correlated with differentiation, positive oestrogen and progestagen receptor status, and low mitotic index. Tumours with good prognosis (less than 20 mm, negative lymph nodes, some degree of differentiation) showed significantly higher PGF2 alpha levels than tumours with a bad prognosis (greater than 20 mm, positive nodes and undifferentiated). A tendency for elevated PGF2 alpha levels was observed with negative lymphatic permeation, postmenopausal status, low grade of nuclear and cellular polymorphism and high degree of elastosis and fibrosis. No correlation was observed between PGF2 alpha levels and host-cell reaction. Plasma levels of 15-keto-13, 14-dihydro-PGF2 alpha were not elevated in cancer patients when compared with the SCD-group. The present study demonstrates that PGF2 alpha levels are high in tumours with good prognosis. However, since other authors have suggested that a high PGE2 production is a bad prognostic index, it is possible that conversion of PGE2 to PGF2 alpha by 9-keto-reductase explains this relationship. Nevertheless, the presented results question the unrestricted use of prostaglandin-synthesis-inhibitors in the treatment of breast cancer.

The concentrations of 6-keto-PGF1 alpha and TXB2 in plasma samples from patients with benign and malignant tumours of the breast

Peripheral plasma concentrations of 6-keto-PGF1 alpha and TXB2 were measured in patients with benign and malignant tumours of the breast, in patients with non-gynecological diseases, and in healthy female controls. The values were significantly higher in female patients with malignant tumours of the breast than in healthy controls (146 +/- 28 vs 13 +/- 2.5 pg/ml for 6-keto-PGF1 alpha p less than 0.01 and 78 +/- 17 vs 11 +/- 2 pg/ml for TXB2, p less than 0.01). Benign tumours of the breast were also associated with significantly raised plasma levels of 6-keto-PGF1 alpha and TXB2 compared to normal controls (52 +/- 5 vs 13 +/- 2.5 pg/ml for 6-keto-PGF1 alpha, p less than 0.01 and 26 +/- 5 vs 11 +/- 2 pg/ml for TXB2, p less than 0.05). The high levels of 6-keto-PGF1 alpha and TXB2 were not found to be correlated with clinical and histopathological data. The surgical removal of the primary tumour has apparently no effect on the plasma concentrations of 6-keto-PGF1 alpha and TXB2 over a follow-up period of 9 days after operation. The lack of alterations in the ratio of TXB2:6-keto-PGF1 alpha in the cancer patients and other subjects studied before and after surgery is indicative of the regulatory power of metabolic systems to preserve the homeostatic balance.

Plasma and urine cyclic nucleotide levels in patients with neoplastic diseases

Plasma and/or urine cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP) levels were measured in 67 normal subjects, 55 patients with nonneoplastic diseases, and 324 patients with ten different types of cancer. There were no significant differences in plasma and urine cyclic nucleotide levels between normal subjects and patients with non-neoplastic diseases. In untreated cancer patients, plasma and urine cAMP levels were similar to those of normal subjects, whereas plasma and urine cGMP levels were markedly higher. This pattern was common to all the cancer groups studied. Chemotherapy per se did not seem to influence cyclic nucleotide levels in cancer patients. However, plasma and urine cGMP levels normalized in all patients who attained complete remission. Moreover, in acute leukemia patients who relapsed, plasma cGMP levels increased significantly with respect to the complete remission values, thus suggesting that this parameter may be useful in monitoring the response of cancer patients to treatment.