Oxytocin and oxytocin receptors in cancer cells and proliferation

Dual role of pregnancy in breast cancer risk

Reproductive history is one of the strongest risk factors for breast cancer in women. Pregnancy can promote short-term breast cancer risk, but also reduce a woman's lifetime risk of breast cancer. Changes in hormone levels before and after pregnancy are one of the key factors in breast cancer risk. This article summarizes the changes in hormone levels before and after pregnancy, and the roles of hormones in mammary gland development and breast cancer progression. Other factors, such as changes in breast morphology and mammary gland differentiation, changes in the proportion of mammary stem cells (MaSCs), changes in the immune and inflammatory environment, and changes in lactation before and after pregnancy, also play key roles in the occurrence and development of breast cancer. This review discusses the dual effects and the potential mechanisms of pregnancy on breast cancer risk from the above aspects, which is helpful to understand the complexity of female breast cancer occurrence.

Dual COX-2/5-LOX inhibitors from Zanthoxylum simulans inhibit gastric cancer cells by cross-mediating thyroid, estrogen, and oxytocin signaling pathways

Cyclooxygenase 2 (COX-2) and 5-lipoxygenase (5-LOX) are overexpressed in gastric cancer cells, the dual inhibitors of which exhibit potential against metastasis and invasion with fewer side effects. To discover inhibitors targeting COX-2 and 5-LOX, we conducted ultrafiltration and enrichment calculation to screen candidates in quaternary alkaloids (QAs) from Zanthoxylum simulans through LC and LC-Q-TOF. For intensive peaks, peaks 19 (berberine) and 21 (chelerythrine) were observed as the most potent dual candidates and showed selective affinity to 5-LOX over COX-2. Peak 19 showed an enrichment at 4.36 for COX-2 and 22.81 for 5-LOX, while peak 21 showed an enrichment at 7.81 for COX-2 and 24.49 for 5-LOX. Molecular docking results revealed chelerythrine as a better dual inhibitor, showing time- and dose-dependent anti-proliferation against AGS cells. Bio-informatics strategies, such as Gene Expression Omnibus (GEO), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG), suggested that hormone pathways in gastric cancer cells might be mediated by chelerythrine. Further reviews and summaries helped outline the mechanisms by which COX-2/5-LOX inhibitors might promote apoptosis in gastric cancer cells via estrogen, thyroid, and oxytocin signaling pathways. Chelerythrine was also added to gastric cancer cells to verify the regulation of these three signaling pathways. As a result, significant calling back of thyroid-stimulating hormone receptor (TSHR), thyroid hormone α3 (TRα3), and thyroid hormone receptor β1 (TRβ1) and suppressing estrogen receptor α36 (ER-α36)-Src could benefit the anti-proliferation of chelerythrine. However, it was disappointing that regulation of estrogen receptor α66 (ER-α66), estrogen receptor β (ER-β), and oxytocin receptor (OTR) contributed inversely negative effects on anti-gastric cancer cells. At present, the integrative study not only revealed chelerythrine as the most potent dual COX-2/5-LOX inhibitor from QAs but also generally highlighted that comprehensive regulation of the estrogen, thyroid, and oxytocin pathway should be noted once gastric cancer cells were treated with inflammatory inhibitors.

The effectiveness of oxytocin in the treatment of stimulant use disorders: a systematic review

OBJECTIVES

The purpose of this review is to examine human study evidence on the effectiveness of oxytocin in this patient population. Despite stimulant use disorder being a major public health concern, there are no validated pharmacological treatments. Psychosocial interventions show limited effectiveness especially in the more severe cases of stimulant use disorder, whereas animal models suggest that oxytocin may be a useful treatment.

METHODS

A literature search using Medline, Embase, and PsychInfo was undertaken. Search results were subsequently imported into Covidence to identify relevant studies.

RESULTS

Six studies were included in this review, two of which were pilot studies. Although oxytocin was well tolerated across studies, no study showed a statistically significant reduction in reported cocaine use or cravings. One study suggested oxytocin increased the desire to use cocaine, although the population of participants should be taken into consideration. In contrast, one study showed a trend towards reduced self-reported cocaine use.

CONCLUSION

Available research does not support the use of oxytocin in the management of stimulant use disorder; however, included studies are small in sample size and limited in number. There were several noteworthy findings unrelated to this review's primary and secondary outcomes, which are of interest and warrant further research. We provide suggestions for future studies in this area of research. Considering the limited data available at this time, further studies are required before any definitive conclusions can be made regarding the use of oxytocin in stimulant use disorder management.

The efficacy of oxytocin gel in postmenopausal women with vaginal atrophy: an updated systematic review and meta-analysis

BACKGROUND

Genitourinary syndrome of menopause (GSM) is a common and disturbing issue in the postmenopausal period. Unlike vasomotor symptoms, it has a progressive trend. Our study aims to evaluate the efficacy and safety of oxytocin gel versus placebo gel in postmenopausal women with GSM.

METHODS

A systematic review and meta-analysis synthesizing randomized controlled trials (RCTs) from Web of Science, SCOPUS, PubMed, and Cochrane Central Register of Controlled Trials databases on January 18, 2023. Keywords such as "oxytocin," "intravaginal," "vaginal," "atrophic," and "atrophy" were used. We used Review Manager (RevMan) version 5.4 in our analysis. We used the risk ratio (RR) for dichotomous outcomes and the mean difference (MD) for continuous outcomes; both were presented with the corresponding 95% confidence interval (CI) and were calculated with the Mantel-Haenszel or inverse variance statistical method. Cochrane's Q test and the I2 statistic were used as measures of statistical inconsistency and heterogeneity. The Cochrane Risk of Bias Tool for RCTs was used for the quality assessment of the included studies.

RESULTS

Seven studies with 631 patients were included. Regarding the maturation index, there was a statistically insignificant increase in the oxytocin arm (MD = 12.34, 95% CI (-12.52-37.19), P = 0.33). Clinically assessed vaginal atrophy showed a statistically significant reduction in the oxytocin group (RR = 0.32, 95% CI (0.23 - 0.10), P < 0.00001). For dyspareunia, vaginal pH, and histological evaluation of vaginal atrophy, there was a statistically insignificant difference between the two groups (RR = 1.02, 95% CI (0.82-1.27), P = 0.84), (MD = -0.74, 95% CI (-1.58-0.10), P = 0.08), and (MD = -0.38, 95% CI (-0.82-0.06), P = 0.09), respectively. There was no significant difference in the safety profile between the two groups as measured by endometrial thickness (MD = 0.00, 95% CI (-0.23-0.23), P = 0.99).

CONCLUSIONS

Although oxytocin has been proposed as a viable alternative to estrogen in the treatment of GSM, our findings show the opposite. Larger, high-quality RCTs are needed to confirm or refute our results.

TRIAL REGISTRATION

PROSPERO registration number CRD42022334357.

Effect of topical oxytocin gel on vaginal mucosa in postmenopausal Egyptian women: a clinical randomized trial

BACKGROUND

Vaginal atrophy is common after menopause and is often linked to sexual dysfunction, particularly dyspareunia.

AIM

The study aimed to investigate the effect of intravaginally applied oxytocin on expressions of vaginal atrophy.

METHODS

Fifty postmenopausal women aged 47 to 66 years with vaginal atrophy participated in this double-blinded placebo-controlled study. The women were randomized to intravaginal treatment with either gel with 600 IU/mL of oxytocin (oxytocin group) or gel alone (control group) once daily for 2 weeks. The gel consisted of hypromellose, pH 3.8 (Vagovital).

OUTCOMES

The color of the vaginal mucosa, the vaginal pH, and the cytology of vaginal epithelial cells were investigated before and after treatment.

RESULTS

The color of the vaginal mucosa shifted from pale to red in all 25 patients treated with oxytocin but only in 4 patients in the control group (P < .001). There was a significant decrease in intravaginal pH in the oxytocin group and the control group, with the delta value being significantly greater in the oxytocin group than in the control group (P < .001). The vaginal maturation index increased significantly (P < .001) in the oxytocin group but not in the control group.

CLINICAL IMPLICATIONS

Topical oxytocin gel offers an effective solution to the sexual dysfunction that is related to vaginal atrophy after menopause.

STRENGTHS AND LIMITATIONS

Strengths include studying different outcomes of applying the oxytocin gel for vaginal atrophy. Limitations include the small-scale population with a relatively short duration of treatment (2 weeks).

CONCLUSION

Intravaginal treatment with a gel containing 600 IU/mL of oxytocin effectively counteracts physical expressions of vaginal atrophy.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT05275270; https://clinicaltrials.gov/ct2/show/NCT05275270).

Oxytocin accelerates tight junction formation and impairs cellular migration in 3D spheroids: evidence from Gapmer-induced exon skipping

Oxytocin (OXT) is a neuropeptide that has been associated with neurological diseases like autism, a strong regulating activity on anxiety and stress-related behavior, physiological effects during pregnancy and parenting, and various cellular effects in neoplastic tissue. In this study, we aimed to unravel the underlying mechanism that OXT employs to regulate cell-cell contacts, spheroid formation, and cellular migration in a 3D culture model of human MLS-402 cells. We have generated a labeled OXT receptor (OXTR) overexpressing cell line cultivated in spheroids that were treated with the OXTR agonists OXT, Atosiban, and Thr4-Gly7-oxytocin (TGOT); with or without a pre-treatment of antisense oligos (Gapmers) that induce exon skipping in the human OXTR gene. This exon skipping leads to the exclusion of exon 4 and therefore a receptor that lost its intracellular G-protein-binding domain. Sensitive digital PCR (dPCR) provided us with the means to differentiate between wild type and truncated OXTR in our cellular model. OXTR truncation differentially activated intracellular signaling cascades related to cell-cell attachment and proliferation like Akt, ERK1/2-RSK1/2, HSP27, STAT1/5, and CREB, as assessed by a Kinase Profiler Assay. Digital and transmission electron microscopy revealed increased tight junction formation and well-organized cellular protrusions into an enlarged extracellular space after OXT treatment, resulting in increased cellular survival. In summary, OXT decreases cellular migration but increases cell-cell contacts and therefore improves nutrient supply. These data reveal a novel cellular effect of OXT that might have implications for degenerating CNS diseases and tumor formation in various tissues.

High Oxytocin Receptor Expression Linked to Increased Cell Migration and Reduced Survival in Patients with Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with limited treatment options and high mortality. The oxytocin receptor (OTR) is a class-A G protein-coupled receptor that has been linked to breast cancer, but its role in tumorigenesis and disease progression remains underexplored. OTR expression is highest in tumour-adjacent breast tissue, followed by normal and tumour tissue, indicating a potential role in the tumour microenvironment. OTR levels were higher in migrated MDA-MB-231 cells than in the control parental cells cultured in normal medium; OTR overexpression/knock-down and metastasis biomarker experiments revealed that high OTR expression enhanced metastasis capabilities. These findings align well with data from a murine breast cancer metastasis model, where metastasised tumours had higher OTR expression than the corresponding primary tumours, and high OTR expression also correlates to reduced survival in TNBC patients. OTR agonists/antagonists did not affect MDA-MB-231 cell migration, and pharmacological analysis revealed that the OT/OTR signalling was compromised. High OTR expression enhanced cell migration in an OTR ligand-independent manner, with the underlying mechanism linked to the EGF-mediated ERK1/2-RSK-rpS6 pathway. Taken together, high OTR expression seems to be involved in TNBC metastasis via increasing cell sensitivity to EGF. These results support a potential prognostic biomarker role of OTR and provide new mechanistic insights and opportunities for targeted treatment options for TNBC.

Synergistic antitumor activity of 5-fluorouracil and atosiban against microsatellite stable colorectal cancer through restoring GATA3

Clinically, 5-fluorouracil (5-Fu) is a first-line drug for the treatment of patients with colorectal cancer (CRC). However, chemoresistance to 5-Fu-based chemotherapy is a leading obstacle in achieving effective treatment for CRC, especially microsatellite stable (MSS) CRC. Since the cytotoxicity of 5-Fu is negatively correlated with oxytocin receptor (OXTR) expression in MSS CRC cell lines, our current study aimed to investigate the synergistic antitumor activity of 5-Fu combined with atosiban, an antagonist of OXTR. Our results suggested that atosiban remarkably potentiated the inhibitory effect of 5-Fu on the growth of MSS-type CRC cells in vitro and in vivo. Moreover, 5-Fu induced GATA3 in MSS CRC cells and tumors, which were eradicated by atosiban. Further investigation showed that atosiban strengthened the antitumor activity of 5-Fu through eradiation of 5-Fu-induced GATA3 in MSS-type CRC cells. Taken together, our findings suggest that atosiban potentiates the antitumor effect of 5-Fu by abolishing 5-Fu-induced GATA3, which provides a novel therapeutic strategy for MSS-type CRC via the combination of atosiban and 5-Fu.

Prognostic role of oxytocin receptor in colon adenocarcinoma

The oxytocin receptor (OXTR) is directly involved in the pathological mechanisms of multiple cancers, including breast cancer, prostate cancer, and ovarian cancer; however, the role of OXTR in the modulation of colon adenocarcinoma (COAD) growth, metastasis, and clinical prognosis remains to be elucidated. This study used systematic bioinformatics analysis to explore the effects of OXTR on modulating COAD growth and prognosis in patients with COAD. Compared with normal tissues, OXTR mRNA level was higher in COAD tissues, which was associated with tumor progression. Elevated mRNA level of OXTR also indicated a poor prognosis in COAD patients. Furthermore, high mRNA level of OXTR was significantly associated with pathways involved in cell cycle regulation and signal transduction pathways, including the hedgehog, mTOR, TGF-β, and Wnt signaling pathways. OXTR expression was significantly correlated with the infiltration level of type 2T helper cell, central memory CD8 T cell, CD56 bright natural killer cell, activated CD8 T cell, activated B cell, and Type 1T helper cell. Moreover, silencing OXTR inhibited cell proliferation, migration, and invasion, and arrested the cell cycle. In conclusion, high mRNA level of OXTR indicates poor prognosis.

Oxytocin stimulates lipolysis, prostaglandin E2 synthesis, and leptin secretion in 3T3-L1 adipocytes

A model of oxytocin in the regulation of metabolic status has described one of oxytocin synthesis and release from the neurohypophysis in response to leptin, to suppress further leptin release. In addition, a lipogenic role for oxytocin has been suggested, consistent with an insulinergic action. This model, however, may be incorrect. Oxytocin reduces fat mass in the absence of either leptin or leptin receptor signalling, thereby challenging the interdependence between leptin and oxytocin. An oxytocin induced production of the anti-lipolytic prostaglandin E₂ (PGE₂) might account for this. Media from 3T3-L1 differentiated adipocytes treated with oxytocin (0-50 nmol.L^-1) for 24 hrs were assayed for PGE₂, leptin, adiponectin, and glycerol. Harvested cells were analysed for lipid droplet triglyceride and cytosolic free fatty acid (FFA) by flow cytometry, and for altered expression of lipolytic and lipogenic associated gene ontology transcripts by cDNA array. Both PGE₂ and leptin secretion were significantly increased by oxytocin treatment whilst adiponectin secretion was not. A significant increase in cytosolic FFA was detected following oxytocin treatment, similar to that determined following treatment with isoproterenol (positive control). A significant increase in glycerol release to the culture media confirmed a lipolytic effect. No enrichment of lipolytic and lipogenic associated gene ontology transcripts was determined, but significant overrepresentation of chemosensory olfactory transcripts was. In conclusion, oxytocin stimulates lipolysis in 3T3-L1 adipocytes, mediated by autocrine/paracrine actions of PGE₂ and leptin. To confirm that this response is mediated solely by the oxytocin receptor, further experiments would require those effects being blocked by a specific oxytocin antagonist.

Oxytocin receptor is a promising therapeutic target of malignant mesothelioma

Malignant mesothelioma (MM) is one of the most aggressive tumors. We conducted bioinformatics analysis using Cancer Cell Line Encyclopedia (CCLE) datasets to identify new molecular markers in MM. Overexpression of oxytocin receptor (OXTR), which is a G‐protein–coupled receptor for the hormone and neurotransmitter oxytocin, mRNA was distinctively identified in MM cell lines. Therefore, we assessed the role of OXTR and its clinical relevance in MM. Kaplan‐Meier and Cox regression analyses were applied to assess the association between overall survival and OXTR mRNA expression using The Cancer Genome Atlas (TCGA) datasets. The function of OXTR and the efficacy of its antagonists were investigated in vitro and in vivo using MM cell lines. Consistent with the findings from CCLE datasets analysis, OXTR mRNA expression was highly increased in MM tissues compared with other cancer types in the TCGA datasets, and MM cases with high OXTR expression showed poor overall survival. Moreover, OXTR knockdown dramatically decreased MM cell proliferation in cells with high OXTR expression via tumor cell cycle disturbance, whereas oxytocin treatment significantly increased MM cell growth. OXTR antagonists, which have high selectivity for OXTR, inhibited the growth of MM cell lines with high OXTR expression, and oral administration of the OXTR antagonist, cligosiban, significantly suppressed MM tumor progression in a xenograft model. Our findings suggest that OXTR plays a crucial role in MM cell proliferation and is a promising therapeutic target that may broaden potential therapeutic options and could be a prognostic biomarker of MM.

Integrated chromatin and transcriptomic profiling of patient-derived colon cancer organoids identifies personalized drug targets to overcome oxaliplatin resistance

Colorectal cancer is a leading cause of cancer deaths. Most colorectal cancer patients eventually develop chemoresistance to the current standard-of-care therapies. Here, we used patient-derived colorectal cancer organoids to demonstrate that resistant tumor cells undergo significant chromatin changes in response to oxaliplatin treatment. Integrated transcriptomic and chromatin accessibility analyses using ATAC-Seq and RNA-Seq identified a group of genes associated with significantly increased chromatin accessibility and upregulated gene expression. CRISPR/Cas9 silencing of fibroblast growth factor receptor 1 (FGFR1) and oxytocin receptor (OXTR) helped overcome oxaliplatin resistance. Similarly, treatment with oxaliplatin in combination with an FGFR1 inhibitor (PD166866) or an antagonist of OXTR (L-368,899) suppressed chemoresistant organoids. However, oxaliplatin treatment did not activate either FGFR1 or OXTR expression in another resistant organoid, suggesting that chromatin accessibility changes are patient-specific. The use of patient-derived cancer organoids in combination with transcriptomic and chromatin profiling may lead to precision treatments to overcome chemoresistance in colorectal cancer.

Pregnancy associated breast cancer (PABC): Report from a gestational cancer registry from a tertiary cancer care centre, India

Background

Pregnancy associated breast cancer (PABC) is a rare entity and defined as breast cancer diagnosed during pregnancy or one-year post-partum. There is sparse data especially from low and middle-income countries (LMIC) and merits exploration.

Methods

The study (2013–2020) evaluated demographics, treatment patterns and outcomes of PABC.

Results

There were 104 patients, median age of 31 years; 43 (41%) had triple-negative disease, 31(29.8%) had hormone-receptor (HR) positive and HER2 negative, 14 (13.5%) had HER2-positive and HR negative and 16(15.4%) had triple positive disease. 101(97%) had IDC grade III tumors and 74% had delayed diagnosis. 72% presented with early stage (24, EBC) or locally advanced breast cancer (53, LABC) and received either neoadjuvant (n = 49) or adjuvant (n = 26) chemotherapy and surgery. Trastuzumab, tamoxifen, and radiotherapy were administered post-delivery. At a median follow up of 27 (IQR:19–35) months, the estimated 3-year event-free survival (EFS) for EBC and LABC was 82% (95% CI: 65.2–100) and 56% (95% CI: 42–75.6%) and for metastatic 24% (95% CI: 10.1%–58.5%) respectively.

Of the 104 patients, 34 were diagnosed antepartum (AP) and 15 had termination, 2 had preterm and 16 had full-term deliveries(FTDs). Among postpartum cohort (n = 70), 2 had termination, 1 had preterm, 67 had FTDs. 83(including 17 from AP) children from both cohorts were experiencing normal milestones.

Conclusion

Data from the first Indian PABC registry showed that the majority had delayed diagnosis and aggressive features(TNBC, higher grade). Treatment was feasible in majority and stage matched outcomes were comparable to non-PABCs.

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Pregnancy associated breast cancer (PABC) is a rare and Challenging entity with lack of data from low-middle income countries.

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First Indian data showed that stage matched oncologic outcomes were comparable to non-PABC.

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Obstetric outcomes were similar to non-cancer associated pregnancies with normal cognitive development.

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Creating awareness and early diagnosis is of utmost importance to improve prognosis in this unique entity

The efficacy and safety of intravaginal oxytocin on vaginal atrophy: A systematic review

Genitourinary syndrome of menopause is a major issue in menopausal health. Because unlike vasomotor symptoms, it has a progressive trend. In this regard we conducted a systematic review to evaluate the efficacy of intravaginal oxytocin on postmenopausal vaginal atrophy. A search was performed for published studies in Cochrane Library, MEDLINE, Web of Science, Embase, Scopus, ProQuest, Google Scholar and Persian databases without time and language limitations. Only randomized controlled trials that compared intravaginal oxytocin with placebos were included. The outcome measures were objective and subjective assessed symptoms of vaginal atrophy. Statistical heterogeneity was evaluated using the I². The standardized mean differences were pooled the fixed effects model. Of the five included studies, four studies meta-analysed. The meta-analysis in terms of the cytological analysis (standardized mean difference: 35.13, 95% confidence interval: 32.59-37.67, n = 218, I² = 96%) was statistically significant. In terms of histological assessments (standardized mean difference: -0.38, 95% confidence interval: -0.94 to 0.17, n = 38, I² = 0%) and endometrial thickness (standardized mean difference: 0.05, 95% confidence interval: -0.20 to -0.31, n = 95, I² = 0%), there were no statistically significant differences between the groups. Three studies reported a statistically significant improvement in the subjective symptoms; however, we were unable to perform a meta-analysis. Four of the included studies assessed side effects, but only two studies reported them. Oxytocin as a nonestrogenic compound can be a suitable alternative for the treatment of vaginal atrophy, especially in women with contraindications for using estrogenic compounds. Further good quality clinical trials with long-term follow-ups are recommended to demonstrate the effects of intravaginal gel in the treatment of vaginal atrophy.

Expression of Arginine Vasopressin Type 2 Receptor in Canine Mammary Tumours: Preliminary Results

The aims of this study were to investigate the potential association of arginine vasopressin type 2 receptor (AVPR2) in canine mammary tumours with expression of oestrogen receptors α (ORα) and β (ORβ) and clinicopathological features of the neoplasms. Twenty-six canine mammary tumour samples (11 benign, 15 malignant) were immunolabelled for AVPR2, ORα and ORβ antigens. Moderate to intense immunolabelling of AVPR2 antigen, found in all neoplasms, was not significantly associated with expression of ORα or ORβ antigens or with clinicopathological features. These findings indicate a potential role for AVPR2 in the development of canine mammary tumours and the use of AVPR2-selective vasopressin analogues as therapeutic options.

Oxytocin and oxytocin receptor alterations, decreased survival, and increased chemoresistance in patients with pancreatic cancer

BACKGROUND

Oxytocin (OXT) and its receptor (OXTR) is associated with cancer. The present study was to investigate the correlation between the genetic expression alterations of OXT and OXTR and the outcomes in patients with pancreatic cancer (PC).

METHODS

Information regarding OXT and OXTR genetic alterations and changes in gene expression were retrieved from the Cancer Genome Atlas (TCGA) databases and analyzed using the cBioPortal online tool. We assessed the correlation of overall survival and disease/progression-free months to either OXT or OXTR genetic alterations and changes in gene expression using Kaplan-Meier and Cox regression analyses. Quantitative PCR (qPCR) was conducted to assess the mRNA expression levels of OXT and OXTR in human PC cell lines.

RESULTS

Five percent of PC cases showed mRNA upregulation in the OXT gene. These PC cases also showed genetic alterations and changes in gene expression of OXTR. The median months of survival and disease-free survival were lower for PC cases with genetic alterations and changes in gene expression in the OXT and OXTR genes as compared to those without such alterations. qPCR data showed that OXT and OXTR mRNA expression were 1-fold and 10-fold higher, respectively in PANC-1 cell lines as compared to L3.6pl cell lines in direct negative correlation with responsiveness to gemcitabine.

CONCLUSIONS

These data suggest that OXT and OXTR may potentially be important in PC progression, chemoresistance, and patient survival, and potentially could have prognostic and therapeutic implications in a subset of PC patients.

Oxytocin is a principal hormone that exerts part of its effects by active fragments

Oxytocin is a nonapeptide consisting of a cyclic six amino-acid structure and a tail of three amino acids. It was originally known for its ability to induce milk ejection and to stimulate uterine contractions. More recently, oxytocin has been shown to stimulate social behaviors, and exert pain-relieving, anti-stress/anti-inflammatory and restorative effects. We hypothesize that oxytocin is a principal hormone that, in part, exerts its effects after degradation to active fragments with more specific effect profiles. Experimental findings on rats show that administered oxytocin exerts biphasic effects. For example, after an initial increase in pain threshold, a second more long-lasting increase follows. Blood pressure and cortisol levels initially increase and then reverse into a long-lasting decrease in blood pressure and cortisol. Whereas the initial effects are, the second-phase effects are not blocked by an oxytocin antagonist, but by an opioid mu-antagonist and by an alpha 2-adrenoreceptor antagonist, respectively, suggesting that other receptors are involved. Repeated administration of oxytocin induces multiple anti-stress effects, which are mediated by alpha 2-adrenoreceptors. Repeated administration of linear oxytocin and linear oxytocin fragments with a retained C-terminal reduce spontaneous motor activity, a sedative or anti-stress effect, suggesting that alpha 2-adrenoreceptors have been activated. In contrast, linear mid-fragments stimulate motor activity. Low-intensity stimulation of cutaneous nerves in rats, as well as breastfeeding and skin-to-skin contact between mothers and babies, trigger immediate anti-stress effects. Some of these effects are likely caused by open ring/linear C-terminal fragments activating alpha 2-adrenoreceptors. Oxytocin fragments may be pre-formed and released in the brain or created by metabolic conversion of the principal hormone oxytocin in the central nervous system. Oxytocin and its fragments may also be released from peripheral sites, such as peripheral nerves, the gastrointestinal tract, and blood vessels in response to decreased sympathetic or increased parasympathetic nervous tone. Smaller fragments of oxytocin produced in the periphery may easily pass the blood-brain barrier to induce effects in the brain. In conclusion, oxytocin is linked to many different, sometimes opposite effects. The intact cyclic molecule may act to initiate social interaction and associated psychophysiological effects, whereas linear oxytocin and C-terminal fragments may induce relaxation and anti-stress effects following social interaction. In this way, the principal hormone oxytocin and its fragments may take part in a behavioral sequence, ranging from approach and interaction to calm and relaxation. Linear fragments, with an exposed cysteine-residue, may exert anti-inflammatory and antioxidant effects and thereby contribute to the health-promoting effects of oxytocin.

Effects of Oxytocin on Cell Proliferation in a Corticotroph Adenoma Cell Line

BACKGROUND

Oxytocin (OXT) has been reported to act as a growth regulator in various tumor cells. However, there is a paucity of data on the influence of OXT on cell proliferation of corticotroph adenomas. This study aimed to examine whether OXT affects cell growth in pituitary tumor cell lines (AtT20 and GH3 cells) with a focus on corticotroph adenoma cells.

METHODS

Reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay were conducted with AtT20 cells to confirm the effects of OXT on hormonal activity; flow cytometry was used to assess changes in the cell cycle after OXT treatment. Moreover, the impact of OXT on proliferating cell nuclear antigen (PCNA), nuclear factor κB, and mitogen-activated protein kinase signaling pathway was analyzed by Western blot.

RESULTS

OXT treatment of 50 nM changed the gene expression of OXT receptor and pro-opiomelanocortin within a short time. In addition, OXT significantly reduced adrenocorticotropic hormone secretion within 1 hour. S and G2/M populations of AtT20 cells treated with OXT for 24 hours were significantly decreased compared to the control. Furthermore, OXT treatment decreased the protein levels of PCNA and phosphorylated extracellular-signal-regulated kinase (P-ERK) in AtT20 cells.

CONCLUSION

Although the cytotoxic effect of OXT in AtT20 cells was not definite, OXT may blunt cell proliferation of corticotroph adenomas by altering the cell cycle or reducing PCNA and P-ERK levels. Further research is required to investigate the role of OXT as a potential therapeutic target in corticotroph adenomas.

Oxytocin in the tumor microenvironment is associated with lower inflammation and longer survival in advanced epithelial ovarian cancer patients

BACKGROUND

Prior research demonstrates a protective role for oxytocin in ovarian cancer based on its anti-proliferative, anti-migratory, and anti-invasive effects in vitro and in vivo. However, the role of endogenous oxytocin has not been examined in ovarian cancer patients. Oxytocin also has anti-inflammatory properties that have not been examined in cancer. The purpose of this investigation was to examine relationships between endogenous oxytocin, tumor-associated inflammation (interleukin-6), and survival in advanced epithelial ovarian cancer patients.

METHODS

Tumor microenvironment (ascites) and plasma oxytocin levels were analyzed via ELISA on extracted samples obtained from 79 patients. In vitro models were used to characterize oxytocin and oxytocin receptor expression in four ovarian cancer cell lines and to investigate direct anti-inflammatory effects of oxytocin on tumor cell secretion of interleukin-6. High and variable levels of oxytocin were observed in ascites, up to 200 times greater than in plasma. Higher levels of ascites oxytocin were associated with lower levels of systemic and tumor-associated interleukin-6, an inflammatory cytokine implicated in ovarian tumor progression. Oxytocin also attenuated interleukin-6 secretion from multiple ovarian tumor cell lines in vitro. Higher levels of ascites oxytocin were associated with a significant survival advantage and statistical mediation analyses suggested this effect was partially mediated by interleukin-6.

CONCLUSIONS

These data identify a previously unacknowledged hormone in the ovarian tumor microenvironment and provide initial evidence that oxytocin has protective effects in ovarian cancer via anti-inflammatory mechanisms. Future studies should examine the therapeutic utility of oxytocin.

Expression of Oxytocin Receptors in Canine Mammary Tumours

The aims of the present study were: (1) to investigate the presence of oxytocin receptors in benign and malignant canine mammary tumours (CMTs) and to evaluate the possible association between oxytocin receptor (OTR) expression and the expression of oestrogen receptor (OR) α and ORβ, and (2) to examine associations between receptor expression and tumour size, clinical stage, histological subtype, tumour grading and lymph node status. Forty-three canine mammary tumour samples (19 benign, 24 malignant) were examined by immunohistochemistry to detect OTR, ORα and ORβ expression. Results were expressed as total score for each receptor, calculated as the sum of the percentage of positive cells and the intensity of immunolabelling. In all of the evaluated mammary tumour samples, OTRs were identified and their expression tended to be higher in benign tumours than malignant tumours. Among the malignant tumours, the expression of OTR was significantly higher in grade I and II lesions than in grade III lesions. ORα-positive tumours had a tendency towards a higher OTR total score than ORα-negative tumours. These results report for the first time that CMTs express OTRs and their expression is associated with the presence of ORα. An interaction between oxytocin and the OTR might play a role in the development and progression of this type of neoplasia.

Oxytocin involves in chronic stress-evoked melanoma metastasis via β-arrestin 2-mediated ERK signaling pathway

Stress is associated with an increased risk of lung metastasis in melanoma. However, the underlying mechanism is elusive. Oxytocin (OXT), a neurohormone produced by the hypothalamus, plays a vital role in laboring induction and lactation. Emerging evidence suggests that OXT also regulates human emotions, social cognition, social behaviors and stress-related disorders. Here, we reported that a significant up-regulation of oxytocin receptors (OXTRs) was observed in malignant melanoma. The activation of OXTRs dramatically promoted migration, invasion and angiogenesis but not the proliferation of melanoma cells in vitro and in vivo via β-arrestin 2-dependent ERK-VEGF/MMP-2 pathway. Next, chronic restraint stress significantly elevated the plasma level of OXT. Notably, 21 days chronic restraint stress facilitated lung metastasis of melanoma and reduced overall survival in mice, which were largely abrogated by knocking down either OXTR or β-arrestin 2. These findings provide evidence that chronic stress hormone-OXT promotes lung metastasis of melanoma via a β-arrestin 2-dependent mechanism and suggest that OXT, a novel pro-metastasis factor, is a potential therapeutic target for melanoma.

Clinical value screening, prognostic significance and key pathway identification of miR-204-5p in endometrial carcinoma: A study based on the Cancer Genome Atlas (TCGA), and bioinformatics analysis

BACKGROUND

Endometrial carcinoma is one of the common carcinomas in the female reproductive system. It is reported that miR-204-5p is down-regulated in endometrial carcinoma. However, the mechanism and key pathways of miR-204-5p in endometrial carcinoma have not been clarified.

MATERIAL/METHODS

We evaluated the expression profiles and prognostic value of miR-204-5p expression in endometrial carcinoma by using bioinformatics analysis of a public dataset from TCGA. Drug of endometrial carcinoma from DrugBank, GO analysis, KEGG analysis, PPI network, mutation, as well as assessment of the prognostic significance were performed to the overlapping target genes of miR-204-5p in endometrial carcinoma. The relative expression levels of miR-204-5p target genes in endometrial carcinoma, including SF3B1, FBXW7, SPOP, and BRD4, were assessed by real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

First, through DrugBank website, we obtained target drugs for endometrial carcinoma. MiR-204-5p expression was found to be lower in the endometrial carcinoma tissues than in adjacent normal tissues from TCGA. Next, we identified 143 genes as potential targets of miR-204-5p. Then, through GO enrichment analysis, KEGG signaling pathway and PPI analysis, we revealed the key networks in endometrial carcinoma. Next, mutation and assessment of the prognostic significance of endometrial carcinoma were obtained. At last, in endometrial carcinoma, the relative expression of SF3B1 and BRD4 increased, and the relative expression of FBXW7 decreased.

CONCLUSIONS

MiR-204-5p is down-regulated in endometrial carcinoma and affects the prognostic significance of endometrial carcinoma, which might play an important role in the tumorigenesis of endometrial carcinoma.

Differential expression profiles of the transcriptome in bone marrow-derived cells in lung cancer revealed by next generation sequencing and bioinformatics

A pre-metastatic niche (PMN) facilitates cancer metastasis through mobilization and recruitment of bone marrow-derived cells (BMDCs) and associated factors. In bone marrow, hematogenous cells, including osteoclasts, macrophages and lymphocytes, and mesenchymal cells, including mesenchymal stem cells, osteoblasts and adipocytes, are involved in PMN formation. Patients with lung cancer and metastasis have a poor prognosis and shortened median survival time. Bone marrow has been considered fertile ground for dormant and proliferating tumor cells, and mobilizing and recruiting BMDCs and immune cells can establish a PMN. However, the role of BMDCs in PMN formation is not yet fully understood. The present study aimed to investigate the association between BMDCs and PMN in bone marrow tissue samples. The results demonstrated that bone marrow served an important role in lung cancer progression and that eight pathways were potentially involved, including ‘T-cell receptor signaling pathway’, ‘osteoclast differentiation’, ‘MAPK signaling pathway’, ‘VEGF signaling pathway’, ‘leukocyte transendothelial migration’, ‘signaling pathways regulating the pluripotency of stem cells’, ‘oxytocin signaling pathway’ and ‘cell adhesion molecules (CAMs)’. In addition, the present study investigated the role of BMDCs in facilitating lung cancer metastasis. In conclusion, the results from the present study suggested that molecular alterations in gene expression may provide a novel signature in lung cancer, which may aid in the development of novel diagnostic and therapeutic strategies for patients with lung cancer and bone metastasis.

Preventive effects of oxytocin and oxytocin receptor in breast cancer pathogenesis

AIM

Modifications of oxytocin (OT) concentration and OT receptor (OXTR) expression level have different effects on breast cancer-derived cells. This study was conducted to evaluate OT variation in breast cancer patients and to evaluate OXTR expression changes in breast cancer tissues.

METHODS

The plasma concentrations of OT in both breast cancer patients and healthy individuals' samples were assessed. OXTR variations were then assessed in both cancerous and noncancerous breast tissues.

RESULTS

OT had an increase in breast cancer patients and expression of OXTR in contralateral breast was more than cancerous tissues.

CONCLUSION

Despite the high levels of OT concentration in breast cancer patients, it seems that a lower expression of OXTR in cancerous tissues can be effective in the breast cancer progression.

Oxytocin and cancer: An emerging link

The neuropeptide hormone oxytocin, which is released from the posterior pituitary gland, is involved in a number of physiological processes. Understanding of its effects is gradually increasing due to new research in this area. While mostly recognized as a reproductive system hormone, oxytocin also regulates other organ systems such as the brain and cardiovascular system. Recently, research has focused on unraveling its involvement in cancer, and emerging evidence suggests a potential role for oxytocin as a cancer biomarker. This review summarizes observations linking oxytocin and cancer, with a special emphasis on prostate cancer, where it may promote cell proliferation. Research suggests that oxytocin effects may depend on cell type, concentration of the hormone, its interactions with other hormones in the microenvironment, and the precise localization of its receptor on the cell membrane. Future research is needed to further elucidate the involvement of oxytocin in cancer, and whether it could be a clinical cancer biomarker or therapeutic target.

Exploratory analysis of the human breast DNA methylation profile upon soymilk exposure

Upon soy consumption, isoflavone metabolites attain bioactive concentrations in breast tissue possibly affecting health. Though in vitro epigenetic activity of soy metabolites has been described, the in vivo impact on the epigenome is largely unknown. Therefore, in this case-control study, the breast glandular tissue DNA methylome was explored in women undergoing an aesthetic breast reduction. After a run-in phase, 10 generally healthy Belgian or Dutch women received soymilk for 5 days. MethylCap-seq methylation profiles were compared with those of 10 matched controls. Isoflavones and their microbial metabolites were quantified in urine, serum, and glandular breast tissue (liquid chromatography-mass spectrometry) and 17β-estradiol in glandular breast tissue (immunoassay). Global DNA methylation levels were obtained for 6 cases and 5 controls using liquid chromatography-mass spectrometry. Although lower MethylCap-seq coverages were observed, mass spectrometry results and computational LINE-1 methylation analysis did not provide evidence supporting global methylation alterations upon treatment. At a false discovery rate of 0.05, no differentially methylated loci were identified. Moreover, a set of previously identified loci was specifically tested, but earlier reported results could not be validated. In conclusion, after a 5-day soymilk treatment, no major general epigenetic reprogramming in breast tissue could be found in this exploratory study.

Oxytocin effects on experimental skin wound healing

OBJECTIVE

Oxytocin (OXY) has significant effects on mammalian behavior. Next to its role in lactation and social interactions, it is described to support better wound healing as well. However, direct OXY effects on wound healing and the regeneration of the microvascular network are still not clarified. We therefore examined the effects of OXY and an OXY receptor antagonist [atosiban (ATO)] on skin wound healing, focusing on epithelialization and neovascularization.

METHODS

Skin wound healing has been assessed using intravital fluorescence microscopy in a model of full dermal thickness wounds in the dorsal skin fold chamber of hairless mice. Animals received repetitive low or high doses of OXY or ATO. Morphological and cellular characterization of skin tissue repair was performed by histology and in vitro cell assays.

RESULTS

The assessment of skin tissue repair using this therapy regimen showed that OXY and ATO had no major influence on epithelialization, neovascularization, wound cellularity, or inflammation. Moreover, OXY and ATO did neither stimulate nor deteriorate keratinocyte or fibroblast migration and proliferation.

CONCLUSION

In summary, this study is the first to demonstrate that OXY application does not impair skin wound healing or cell behavior. However, until now, the used transmitter system seems not to be clarified in detail, and it might be proposed that it is associated with the stress response of the organism to various stimuli.

A genome-wide association study reveals candidate genes for the supernumerary nipple phenotype in sheep (Ovis aries)

Genome-wide association studies (GWASs) have been widely applied in livestock to identify genes associated with traits of economic interest. Here, we conducted the first GWAS of the supernumerary nipple phenotype in Wadi sheep, a native Chinese sheep breed, based on Ovine Infinium HD SNP BeadChip genotypes in a total of 144 ewes (75 cases with four teats, including two normal and two supernumerary teats, and 69 control cases with two teats). We detected 63 significant SNPs at the chromosome-wise threshold. Additionally, one candidate region (chr1: 170.723-170.734 Mb) was identified by haplotype-based association tests, with one SNP (rs413490006) surrounding functional genes BBX and CD47 on chromosome 1 being commonly identified as significant by the two mentioned analyses. Moreover, Gene Ontology enrichment for the significant SNPs identified by the GWAS analysis was functionally clustered into the categories of receptor activity and synaptic membrane. In addition, pathway mapping revealed four promising pathways (Wnt, oxytocin, MAPK and axon guidance) involved in the development of the supernumerary nipple phenotype. Our results provide novel and important insights into the genetic mechanisms underlying the phenotype of supernumerary nipples in mammals, including humans. These findings may be useful for future breeding and genetics in sheep and other livestock.

Regulation of angiogenic behaviors by oxytocin receptor through Gli1-indcued transcription of HIF-1α in human umbilical vein endothelial cells

Angiogenesis is a dynamic hypoxia-stimulated process playing a key role in tissue growth and repair under various pathophysiological circumstances. Abnormal angiogenesis contributes to the pathogenesis of many human diseases. Oxytocin receptor is a classical G-protein-coupled receptor expressed on endothelial cells. The present study was aimed to investigate how oxytocin receptor regulated the angiogenic behaviors of human umbilical vein endothelial cells (HUVECs). We found that oxytocin at 0.1μM significantly increased cell proliferation, upregulated the mRNA and protein expression of CD31 and vWF (two important endothelial markers), and enhanced the tuber formation capacity in HUVECs. However, oxytocin receptor inhibitor atosiban at 10μM significantly suppressed these angiogenic properties of HUVECs. Additionally, hypoxia-inducible factor-1α (HIF-1α) inhibitor PX-478 at 20μM also remarkably inhibited the angiogenic properties of HUVECs. We further found that atosiban at 10μM significantly repressed the promoter activity of HIF-1α and reduced the mRNA and protein expression of HIF-1α in HUVECs. Moreover, pharmacological inhibition of HIF-1α by PX-478 at 20μM abolished oxytocin-enhanced angiogenic properties of HUVECs. Finally, transcription factor Gli1 inhibitor GANT-58 at 5μM significantly abolished oxytocin-induced mRNA and protein expression of HIF-1α, while the nuclear abundance of Gli1 was significantly reduced by atosiban at 10μM, but was increased by oxytocin at 0.1μM in HUVECs. GANT-58 at 5μM also significantly abolished oxytocin-enhanced angiogenic properties of HUVECs. Altogether, these discoveries suggested that oxytocin receptor signaling promoted the angiogenic behaviors of HUVECs via Gli1-indcued transcription of HIF-1α. We provided novel molecular insights into endothelial cell-mediated angiogenesis.

Oxytocin-secreting system: A major part of the neuroendocrine center regulating immunologic activity

Interactions between the nervous system and immune system have been studied extensively. However, the mechanisms underlying the neural regulation of immune activity, particularly the neuroendocrine regulation of immunologic functions, remain elusive. In this review, we provide a comprehensive examination of current evidence on interactions between the immune system and hypothalamic oxytocin-secreting system. We highlight the fact that oxytocin may have significant effects in the body, beyond its classical functions in lactation and parturition. Similar to the hypothalamo-pituitary-adrenal axis, the oxytocin-secreting system closely interacts with classical immune system, integrating both neurochemical and immunologic signals in the central nervous system and in turn affects immunologic defense, homeostasis, and surveillance. Lastly, this review explores therapeutic potentials of oxytocin in treating immunologic disorders.

An Exploratory Study of the Effects of Mind–Body Interventions Targeting Sleep on Salivary Oxytocin Levels in Cancer Survivors

Cancer survivors experience high levels of distress, associated with a host of negative psychological states, including anxiety, depression, and fear of recurrence, which often lead to sleep problems and reduction in quality of life (QOL) and well-being. As a neuropeptide hormone associated with affiliation, calmness, and well-being, oxytocin may be a useful biological measure of changes in health outcomes in cancer survivors. In this exploratory study, which comprised a subset of participants from a larger study, we evaluated ( a) the feasibility and reliability of salivary oxytocin (sOT) levels in cancer survivors and ( b) the effects of 2 sleep-focused mind–body interventions, mind–body bridging (MBB) and mindfulness meditation (MM), compared with a sleep hygiene education (SHE) control, on changes in sOT levels in 30 cancer survivors with self-reported sleep disturbance. Interventions were conducted in 3 sessions, once per week for 3 weeks. Saliva samples were collected at baseline, postintervention (~1 week after the last session), and at the 2-month follow-up. In this cancer survivor group, we found that intra-individual sOT levels were fairly stable across the 3 time points, of about 3 months’ duration, and mean baseline sOT levels did not differ between females and males and were not correlated with age. Correlations between baseline sOT and self-report measures were weak; however, several of these relationships were in the predicted direction, in which sOT levels were negatively associated with sleep problems and depression and positively associated with cancer-related QOL and well-being. Regarding intervention effects on sOT, baseline-subtracted sOT levels were significantly larger at postintervention in the MBB group as compared with those in SHE. In this sample of cancer survivors assessed for sOT, at postintervention, greater reductions in sleep problems were noted for MBB and MM compared with that of SHE, and increases in mindfulness and self-compassion were observed in the MBB group compared with those in SHE. The findings in this exploratory study suggest that sOT may be a reliable biological measure over time that may provide insight into the effects of mind–body interventions on health outcomes in cancer survivors.

Suicide attempt and future risk of cancer: a nationwide cohort study in Sweden

PURPOSE

Little is known about cancer incidence among patients with a history of suicide attempt. Suicide attempters have lower levels of oxytocin, a hormone related to lactation, stress, social functioning, and well-being, and recent research indicates influence on carcinogenesis. We hypothesized that the low oxytocin levels among suicide attempters results in an increased risk of cancer in general and in organs with oxytocin receptors in particular.

METHODS

A nationwide cohort study of patients aged 15 years or older with hospitalization for self-inflicted injury or attempted suicide was identified from the Swedish patient register in 1968-2011. The cancer outcomes were identified from the Swedish cancer register. Cancer risk in suicide attempters was compared with the risk in the background population of the corresponding age, sex, and calendar period by calculating standardized incidence ratios (SIRs) with 95 % confidence intervals (95 % CI).

RESULTS

The 186,627 patients (83,637 men and 102,990 women) hospitalized for self-inflicted injury or attempted suicide contributed with 2.6 million person-years at risk. The SIR for all cancer was 1.3 (95 % CI 1.27-1.33) in men and 1.25 (1.22-1.28) in women. For cancers in organs rich in oxytocin receptors (uterus, breast, and brain), the corresponding SIRs were 1.02 (0.87-1.19) and 1.13 (1.09-1.17), respectively. There was a particularly increased risk of cancers related to alcohol and tobacco in both sexes.

CONCLUSION

Patients attempting suicide have an increased risk of cancer. However, this increase does not seem to be associated with low oxytocin levels, but rather to exposures like tobacco smoking and alcohol consumption.

Oxytocin has therapeutic effects on cancer, a hypothesis

Oxytocin (OT) is the first peptide hormone structurally assessed and chemically synthesized in biologically active form. This hormone acts as an important factor in a human reproductive system particularly during pregnancy and lactation in women. So far, different therapeutic roles for OT have been identified as a spectrum from central and peripheral actions on male and female reproductive systems, circulatory system, musculoskeletal system, etc. Some in vitro and in vivo studies also revealed that OT is responsible for bivariate biological functions involved in cancer as following. By activating OT receptor in tumoral cells, OT enacts as a growth regulator, whether activator or inhibitor. Regarding the increase of OT in some conditions such as breastfeeding, exercise, and multiparity, we can relate the effect of these conditions on cancer with OT effects. Based on this hypothesis, we present a review on the effects of this neuropeptide on various types of cancer and also the influence of these conditions on the same cancer.

Overexpression of membrane proteins in primary and metastatic gastrointestinal neuroendocrine tumors

BACKGROUND

Small bowel and pancreatic neuroendocrine tumors (SBNETs and PNETs) are rare tumors whose incidence is increasing. Drugs targeting the somatostatin receptor are beneficial in these tumors. To identify additional cell-surface targets, we recently found receptors and membrane proteins with gene expression significantly different from adjacent normal tissues in a small number of primary SBNETs and PNETs. We set out to validate these expression differences in a large group of primary neuroendocrine tumors and to determine whether they are present in corresponding liver and lymph node metastases.

METHODS

Primary SBNETs and PNETs, normal tissue, nodal, and liver metastases were collected and mRNA expression of six target genes was determined by quantitative PCR. Expression was normalized to GAPDH and POLR2A internal controls, and differences as compared to normal tissue were assessed by Welch's t test.

RESULTS

Gene expression was determined in 45 primary PNETs with 20 nodal and 17 liver metastases, and 51 SBNETs with 50 nodal and 29 liver metastases. Compared to normal tissue, the oxytocin receptor (OXTR) showed significant overexpression in both primary and metastatic SBNETs and PNETs. Significant overexpression was observed for MUC13 and MEP1B in PNET primary tumors, and for GPR113 in primary SBNETs and their metastases. SCTR and ADORA1 were significantly underexpressed in PNETs and their metastases. OXTR protein expression was confirmed by immunohistochemistry.

CONCLUSIONS

OXTR is significantly overexpressed relative to normal tissue in primary SBNETs and PNETs, and this overexpression is present in their liver and lymph node metastases, making OXTR a promising target for imaging and therapeutic interventions.

Oxytocin administration attenuates atherosclerosis and inflammation in Watanabe Heritable Hyperlipidemic rabbits

Oxytocin (OT) is a neurohypophyseal peptide traditionally associated with female reproductive functioning, and more recently with prosocial behavior. OT and its receptor are also expressed in the heart and vascular tissue and play a role in cardiovascular homeostasis. In vitro, it has been demonstrated that OT decreases NADPH-dependent superoxide production and pro-inflammatory cytokine release from vascular endothelial cells and macrophages, suggesting that OT may attenuate pathophysiological processes involved with atherosclerotic lesion formation. The present study sought to determine the effect of chronic exogenous OT administration on inflammation and atherosclerosis in an animal model of dyslipidemia and atherosclerosis, the Watanabe Heritable Hyperlipidemic (WHHL) rabbit. Twenty-two, 3-month-old WHHLs were surgically implanted with osmotic mini-pumps containing OT (n=11) or vehicle (n=11), and then were individually housed for the entire study. Blood and 24-h urine samples were taken at baseline and after 8 (midpoint) and 16 (endpoint) weeks of treatment. At endpoint, the aortas and visceral fat samples were dissected and stored for analyses. There were no group differences in body weight, serum lipids, plasma/urinary measures of oxidative stress, plasma cortisol or urinary catecholamines over the 16-week treatment. OT-treated animals exhibited significantly lower plasma C-reactive protein levels at midpoint and endpoint and developed significantly less atherosclerosis in the thoracic aorta relative to vehicle control animals at endpoint (p<0.05). Cytokine gene expression from visceral adipose tissue samples suggested that there was a decrease in adipose tissue inflammation in the OT-treated group compared to the vehicle control group, however these differences were not statistically significant. These results suggest that chronic peripheral OT administration can inhibit inflammation and atherosclerotic lesion development.

Deciphering the specific role of Gαi/o isoforms: functional selective oxytocin ligands and somatostatin SST5 receptor mutants

Receptor coupling to different G-proteins and β-arrestins has been described for a number of GPCRs (G-protein-coupled receptors), suggesting a multi-state model of receptor activation in which each receptor can assume a number of different active conformations, each capable of promoting the coupling to a specific effector. Consistently, functional-selective ligands and biased agonists have been described to be able to induce and/or stabilize only a subset of specific active conformations. Furthermore, GPCR mutants deficient in selective coupling have been reported. Functional selective ligands and receptor mutants thus constitute unique tools to dissect the specific roles of different effectors, in particular among the Gi/o family. In the present mini-review, we focus on (i) the identification of functional selective OXT (oxytocin)-derived peptides capable of activating single Gi/o isoforms, namely Gi1 or Gi3; and (ii) the characterization of an SS (somatostatin) receptor SST5 mutant selectively impaired in its GoA coupling. These analogues and receptor mutants represent unique tools for examining the contribution of Gi/o isoforms in complex biological responses and open the way for the development of drugs with peculiar selectivity profiles.

Oxytocin does not attenuate the ex vivo production of inflammatory cytokines by lipopolysaccharide-activated monocytes and macrophages from healthy male and female donors

BACKGROUND

Oxytocin (OT) is a neuropeptide shown to attenuate inflammatory responses in both humans and animals, but the specific mechanism underlying these actions has not yet been identified. Preliminary research in humans suggests that monocytes (MOs) and macrophages (MPs) could be the target of anti-inflammatory actions of OT. Here, we present a series of ex vivo experiments in human MOs and MPs, testing whether OT attenuates the cytokine responses of these cells to a common bacterial product, lipopolysaccharide (LPS).

METHODS

MO experiments were conducted using blood samples taken from healthy volunteers after obtaining informed consent. MPs were purchased frozen from a cell supplier. All samples were cultured under standard conditions: for 6 h at 37°C in a 5% CO2 atmosphere. A number of variables were considered: volunteer sex, method of MO isolation, LPS concentration, OT concentration, preincubation with OT, cytokines measured, and method of cytokine measurement.

RESULTS

Regardless of the specific conditions, no attenuation of LPS-stimulated cytokine production by OT was observed in either MOs or MPs.

CONCLUSION

OT does not attenuate MO or MP inflammatory cytokine production following LPS stimulation. The previously observed anti-inflammatory properties of OT may be attributable to effects on other classes of immune cells or actions in other lymphoid compartments. Alternatively, the effects of OT on inflammation could be secondary to other neurohormonal changes it elicits.

Salubrious effects of oxytocin on social stress-induced deficits

Social relationships are a fundamental aspect of life, affecting social, psychological, physiological, and behavioral functions. While positive social interactions can attenuate stress and promote health, the social environment can also be a major source of stress when it includes social disruption, confrontation, isolation, or neglect. Social stress can impair the basal function and stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis, impairing function of multiple biological systems and posing a risk to mental and physical health. In contrast, social support can ameliorate stress-induced physiological and immunological deficits, reducing the risk of subsequent psychological distress and improving an individual's overall well-being. For better clinical treatment of these physiological and mental pathologies, it is necessary to understand the regulatory mechanisms of stress-induced pathologies as well as determine the underlying biological mechanisms that regulate social buffering of the stress system. A number of ethologically relevant animal models of social stress and species that form strong adult social bonds have been utilized to study the etiology, treatment, and prevention of stress-related disorders. While undoubtedly a number of biological pathways contribute to the social buffering of the stress response, the convergence of evidence denotes the regulatory effects of oxytocin in facilitating social bond-promoting behaviors and their effect on the stress response. Thus, oxytocin may be perceived as a common regulatory element of the social environment, stress response, and stress-induced risks on mental and physical health. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

Topical oxytocin reverses vaginal atrophy in postmenopausal women: a double-blind randomized pilot study

Introduction

Oxytocin is a peptide hormone produced in the hypothalamus and it is best known for its role in labour and lactation. This double-blind, randomized study was performed at Huddinge Hospital of Karolinska Institutet, Stockholm in order to test the effectiveness of topical oxytocin gel in women with postmenopausal vaginal atrophy.

Methods

Twenty postmenopausal women (at least two years after menopause) with symptoms of vaginal atrophy such as vaginal dryness, pain, itching, discomfort and bleeding during intercourse were enrolled in the study when visual inspection of the vagina had confirmed that their mucosa was atrophic. The participants were randomized to intravaginal treatment with either oxytocin or placebo gel for seven days. Before and after treatment, a gynaecological examination and a visual and colposcopic inspection of the vagina were performed, biopsies from the vaginal mucosa were taken and blood samples were collected for analysis of circulating levels of estradiol and oxytocin.

Results

Prior to treatment, visual and colposcopic inspection showed that all of the 20 participants had an atrophic vaginal mucosa. After treatment with the oxytocin gel, the examination showed that the vaginal epithelium of seven of the 10 participants in the oxytocin group had become healthier and normalized. No change in these parameters was observed among the 10 participants in the placebo group. This difference between the oxytocin and placebo groups was significant ( P= 0.003). Seven participants in the active group and four in the placebo group reported relief of symptoms of vaginal atrophy after seven days of applying the gel. The effect of oxytocin to normalize the morphological appearance of the vaginal mucosa was almost significant when compared with the placebo group ( P= 0.07). There was no significant difference between the circulating levels of estradiol and oxytocin in both the oxytocin and placebo groups before and after treatment. None of the participants reported any side-effects.

Conclusion

Topical treatment with oxytocin appears to improve vaginal atrophy in postmenopausal women. A limitation of this pilot study is that it was based on a small study population hence the results should be regarded with caution. Larger studies are in progress to establish the possibility of using oxytocin as a clinical treatment for vaginal atrophy.

Oxytocin increases invasive properties of endometrial cancer cells through phosphatidylinositol 3-kinase/AKT-dependent up-regulation of cyclooxygenase-1, -2, and X-linked inhibitor of apoptosis protein

Traditionally, oxytocin (OT) is well known to play a crucial role in the regulation of cyclic changes in the uterus, implantation of the embryo, and parturition. Recently, an additional role for OT has been identified in several types of cancer cells in which OT acts as a growth regulator. In endometrial cancer cells, OT is known to efficiently inhibit cellular proliferation. In the present study, we show that OT increases invasiveness of human endometrial carcinoma (HEC) cells, which are otherwise resistant to the growth-inhibiting effects of OT. Using pharmacological inhibitors, invasion assay, RNA interference, and immunofluorescence, we found that OT enhances the invasive properties of HEC cells through up-regulation of X-linked inhibitor of apoptosis protein (XIAP), matrix-metalloproteinase 2 (MMP2), and matrix-metalloproteinase 14 (MMP14). In addition, we show that OT-mediated invasion is both cyclooxygenase 1 (PTGS1) and cyclooxygenase-2 (PTGS2) dependent via the phosphatidylinositol 3-kinase/AKT (PIK3/AKT) pathway. PTGS2 knockdown by shRNA resulted in XIAP down-regulation. We also show that OT receptor is overexpressed in grade I to III endometrial cancer. Taken together, our results describe for the first time a novel role for OT in endometrial cancer cell invasion.

Stress buffering effects of oxytocin on HIV status in low-income ethnic minority women

BACKGROUND

Elevated perceptions of psychosocial stress and stressful life events are linked to faster disease progression in individuals living with HIV and these associations may be stronger for women from ethnic minority populations. Levels of neurohormones such as oxytocin (OT), cortisol, and norepinephrine (NE) have been shown to influence the effects of psychosocial stress in different populations. Understanding how intrinsic neuroendocrine substances moderate the effects of stressors in minority women living with HIV (WLWH) may pave the way for interventions to improve disease management.

METHODS

We examined circulating levels of plasma OT as a moderator of the effects of stress on disease status (viral load, CD4+ cell count) in 71 low-income ethnic minority WLWH.

RESULTS

At low levels of OT, there was an inverse association between stress and CD4+ cell counts. Counter-intuitively, at high levels of OT there was a positive association between stress and CD4+ cell counts. This pattern was unrelated to women's viral load. Other neuroendocrine hormones known to down-regulate the immune system (cortisol, norepinephrine) did not mediate the effects of OT and stress on immune status.

CONCLUSIONS

OT may have stress buffering effects on some immune parameters and possibly health status in low income ethnic minority WLWH reporting elevated stress.

Hypothalamus-pituitary-thyroid axis disruption in rats with breast cancer is related to an altered endogenous oxytocin/insulin-regulated aminopeptidase (IRAP) system

Associations of breast cancer with diseases of the thyroid have been repeatedly reported, but the mechanism underlying this association remains to be elucidated. It has been reported that oxytocin (OXT) attenuates the thyroid-stimulating hormone (TSH) release in response to thyrotrophin-releasing hormone (TRH) and decreased plasma levels of TSH as well as the thyroid hormones by an effect mediated by the central nervous system. Oxytocinase (IRAP) is the regulatory proteolytic enzyme reported to hydrolyze OXT. Changes in IRAP activity have been reported in both human breast cancer and N-methyl-nitrosourea (NMU)-induced rat mammary tumours. Here, we measure IRAP activity fluorometrically using cystyl-β-naphthylamide as the substrate, in the hypothalamus-pituitary-thyroid axis together with the circulating levels of OXT, and its relationship with circulating levels of TSH and free thyroxine (fT4), as markers of thyroid function in control rats and rats with breast cancer induced by NMU. We found decreased thyroid function in rats with breast cancer induced by NMU, supported by the existence of lower serum circulating levels of both TSH and fT4 than their corresponding controls. Concomitantly, we found a decrease of hypothalamic IRAP activity and an increase in circulating levels of OXT. We propose that breast cancer increases OXT pituitary release by decreasing its hypothalamic catabolism through IRAP activity, probably due to the alteration of the estrogenic endocrine status. Thus, high circulating levels of OXT decreased TSH release from the pituitary, and therefore, of thyroid hormones from the thyroid, supporting the association between breast cancer and thyroid function disruption.

The bovine milk proteome: cherishing, nourishing and fostering molecular complexity. An interactomics and functional overview

Bovine milk represents an essential source of nutrients for lactating calves and a key raw material for human food preparations. A wealth of data are present in the literature dealing with massive proteomic analyses of milk fractions and independent targeted studies on specific groups of proteins, such as caseins, globulins, hormones and cytokines. In this study, we merged data from previous investigations to compile an exhaustive list of 573 non-redundant annotated protein entries. This inventory was exploited for integrated in silico studies, including functional GO term enrichment (FatiGO/Babelomics), multiple pathway and network analyses. As expected, most of the milk proteins were grouped under pathways/networks/ontologies referring to nutrient transport, lipid metabolism and objectification of the immune system response. Notably enough, another functional family was observed as the most statistically significant one, which included proteins involved in the induction of cellular proliferation processes as well as in anatomical and haematological system development. Although the latter function for bovine milk proteins has long been postulated, studies reported so far mainly focused on a handful of molecules and missed the whole overview resulting from an integrated holistic analysis. A preliminary map of the bovine milk proteins interactome was also built up, which will be refined in future as result of the widespread use of quantitative methods in protein interaction studies and consequent reduction of false-positives within associated databases.

Oxytocin stimulates in vitro angiogenesis via a Pyk-2/Src-dependent mechanism

We previously reported that the hypothalamic hormone oxytocin (OT), best known for its uterotonic activity, also stimulates migration and invasion in human umbilical vein endothelial cells (HUVECs), thus suggesting a possible role for the peptide in the regulation of angiogenesis. We identified the Gq coupling of OT receptors (OTRs) and phospholipase C (PLC) as the main effectors of OT's action in HUVECs. Moreover, the pro-migratory effect of OT required the OTR-induced activation of the phosphatidylinositol-3-kinase (PI-3-K)/AKT/endothelial nitric oxide synthase (eNOS) pathway. To better characterize the proposed pro-angiogenic effect of OT in HUVECs, we have now utilized a three-dimensional (3-D) in vitro angiogenesis assay, and demonstrated that OT stimulates the outgrowth of capillary-like structures from HUVEC spheroids to an extent comparable to that of vascular endothelial growth factor (VEGF). This OT effect was abolished by inhibitors of PLC, PI-3-K and Src kinase. It was also found that OT phosphorylates proline-rich tyrosine kinase-2 (Pyk-2) and Src kinase in a PLC- and calcium-dependent manner. Furthermore, knockdown of Pyk-2 expression by RNA interference markedly impaired Src phosphorylation, migration and endothelial cell sprouting induced by OT. In conclusion, by using a pharmacological and genetic approach, the OT pro-angiogenic action and the cascade of intracellular signals responsible for it were defined by showing for the first time that OT, by interacting with its Gq-coupled receptor, induces HUVEC capillary outgrowth via Pyk-2 phosphorylation, which activates Src which in turn activates the PI-3-K/AKT pathway.

Oxytocin alleviates the neuroendocrine and cytokine response to bacterial endotoxin in healthy men

Oxytocin is a hormone and neurotransmitter found to have anti-inflammatory functions in rodents. Here we used experimental bacterial endotoxinemia to examine the role of exogenous oxytocin administration on innate immune responses in humans. Ten healthy men received, in a randomized, placebo-controlled, crossover design, placebo, oxytocin, LPS, and LPS + oxytocin. Oxytocin treatment resulted in a transient or prolonged reduction of endotoxin-induced increases in plasma ACTH, cortisol, procalcitonin, TNF-alpha, IL-1 receptor antagonist, IL-4, IL-6, macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, monocyte chemoattractant protein-1 (MCP-1), interferon-inducible protein 10, and VEGF. In vitro, oxytocin had no impact on LPS effects in releasing TNF-alpha, IL-6, and MCP-1 in monocytes and peripheral blood mononuclear cells from healthy human donors. In summary, oxytocin decreases the neuroendocrine and cytokine activation caused by bacterial endotoxin in men, possibly due to the pharmacological modulation of the cholinergic anti-inflammatory pathway. Oxytocin might be a candidate for the therapy of inflammatory diseases and conditions associated with high cytokine and VEGF levels.