Negative association of steroids with immunotherapy efficacy in a multi-tumor cohort: time and dose-dependent.

Previous studies have suggested a negative impact of steroids on the efficacy of immune checkpoint inhibitors (ICI), but how this effect is modulated by the dosage and time of administration is yet to be clarified. We have performed a retrospective analysis of 475 patients with advanced solid tumors treated with ICI as monotherapy from 2015 to 2022. Data regarding immune-related adverse events (irAEs) and clinical outcomes were collected. For each patient, the daily steroid dose (in mg/kg of prednisone) was registered until disease progression or death. The impact of cumulative doses on response rates and survival outcomes was analyzed within different periods. The objective response rate (ORR) was significantly lower among patients exposed to steroids within 30 days before the first cycle of ICI (C1) (20.3% vs. 36.7%, p < 0.01) and within the first 90 days of treatment (25.7% vs. 37.7%, p = 0.01). This negative association was confirmed by multivariable analysis. Higher mean steroid doses were observed among non-responders, and cumulative doses were inversely correlated with the disease control rate (DCR) around ICI initiation. Remarkably, poorer outcomes were observed even in patients belonging to the lowest dose quartile compared to the steroid-naïve population. The exposure to steroids after 6 months of ICI was not associated with worse survival outcomes. Our results suggest that the potential impact of steroids on ICI efficacy may be time-dependent, prevailing around ICI initiation, and dose-dependent, with modulation of neutrophil-to-lymphocyte ratio as a possible underlying mechanism.

Burnout in nursing: A vision of gender and "invisible" unrecorded care.

AIM: To reflect on how characteristics inherent in the nursing profession might be related to burnout syndrome among the nursing collective. BACKGROUND: Most people are unaware of the tasks and responsibilities of the nursing profession, as well as the burnout rates suffered by nurses. The nursing profession is a feminized profession, and this feminization may lead to the assignment of gender stereotypes and roles traditionally attributed to women. Much of the care provided by nurses is unrecorded, "invisible" and could be seen as an extension of their role as caregivers. METHODS: This is a discussion paper. The literature on gender stereotypes, unrecorded (invisible) care in nursing and burnout are the argumentative basis of this work. DISCUSSION: Stereotypes and gender roles may explain the lack of recognition of some of the carework carried out by nurses. Care, which is the essence of the profession, continues to be largely invisible and is not valued. This lack of recognition of invisible care, coupled with gender stereotypes, may help to understand burnout syndrome in nursing. IMPACT FOR NURSING: Health organizations should take into account the history of the nursing profession and the stereotypes associated with it. It is necessary to recognize and make visible much of the care provided by nurses which are not recorded (invisible care), since this would facilitate the visibilization of the workload and could reduce the possibility of suffering burnout. If we want quality care and staff who enjoy the greatest possible well-being, it will be necessary to take these variables into consideration. One purpose should be: to care for them so that they can provide quality care to others. NO PATIENT OR PUBLIC CONTRIBUTION: This is a discussion paper.

Paternal alcohol consumption has intergenerational consequences in male offspring.

PURPOSE: Alcoholism is a heterogeneous set of disorders caused by ethanol intake. Harmful effects of paternal consumption on the offspring are poorly explored and not fully understood. We analyzed the effect of paternal alcohol consumption on both their own reproductive capacity and that of their male offspring. METHODS: We used a model of ethanol consumption (15% v/v in drinking water) for 12 days in adult CF-1 male mice. DNA integrity and post-translational modifications of histones were assessed in sperm; testicular weight, histology, and DNA fragmentation were analyzed. Treated or untreated male mice were mated with non-treated females to obtain two cell embryos that were cultured for 7 days; morphology and embryonic cell death were evaluated. Males of both groups were mated with non-treated females. Adult male offspring was euthanized, and sperm and testicular parameters determined. RESULTS: Paternal ethanol consumption caused histological and epigenetic changes, as well as damage in DNA integrity in the testicular germline and sperm. These alterations gave rise to deleterious effects on embryonic development and to testicular and spermatic changes in the offspring. CONCLUSION: This study provides critical information on reproductive disturbances brought about by paternal alcohol consumption and the profound impact these could have on the male progeny. The need to explore the effects of paternal alcohol consumption in detail and warn about the importance of controlling alcohol intake for the well-being of future generations should not be underscored.

Her-2 Targeted Therapy in Advanced Urothelial Cancer: From Monoclonal Antibodies to Antibody-Drug Conjugates.

Metastatic urothelial cancer, associated with a poor prognosis, is still major cause of cancer-related death, with scarce options of effective treatment after progression to platinum-based chemotherapy and immunotherapy. The human epithelial growth factor receptor 2 (Her-2) has been identified as a new therapeutic target in medical oncology. However, despite the encouraging results in breast and gastric cancers, clinical trials with anti-Her-2 monoclonal antibodies and tyrosine-kinase inhibitors have shown limited efficacy of this strategy in urothelial tumors. Notably, more favorable data have been recently shown that antibody-drug conjugates are currently emerging as a novel promising approach for Her-2 targeted therapy in advanced urothelial cancer.

Receptor Tyrosine Kinase Inhibitors for the Treatment of Recurrent and Unresectable Bone Sarcomas.

Bone sarcomas are a heterogeneous group of rare tumors with a predominance in the young population. Few options of systemic treatment are available once they become unresectable and resistant to conventional chemotherapy. A better knowledge of the key role that tyrosine kinase receptors (VEGFR, RET, MET, AXL, PDGFR, KIT, FGFR, IGF-1R) may play in the pathogenesis of these tumors has led to the development of multi-target inhibitors (TKIs) that are progressively being incorporated into our therapeutic arsenal. Osteosarcoma (OS) is the most frequent primary bone tumor and several TKIs have demonstrated clinical benefit in phase II clinical trials (cabozantinib, regorafenib, apatinib, sorafenib, and lenvatinib). Although the development of TKIs for other primary bone tumors is less advanced, preclinical data and early trials have begun to show their potential benefit in advanced Ewing sarcoma (ES) and rarer bone tumors (chondrosarcoma, chordoma, giant cell tumor of bone, and undifferentiated pleomorphic sarcoma). Previous reviews have mainly provided information on TKIs for OS and ES. We aim to summarize the existing knowledge regarding the use of TKIs in all bone sarcomas including the most recent studies as well as the potential synergistic effects of their combination with other systemic therapies.

The threat of COVID-19 and its influence on nursing staff burnout.

AIMS: To evaluate whether the perceived threat of COVID-19 moderates the influence of work resources and demands on burnout. DESIGN: A cross-sectional study. METHODS: We used a convenience sample of 771 nurses working in 10 hospitals in northern Spain. The data on burnout, demand, and resources at work and the perceived threat of COVID-19 were compiled in the second fortnight of April 2020 using an online questionnaire. We used several hierarchical linear regression models. RESULTS: Work overload, material and human resources and social support at work were significant in explaining burnout. The perceived threat of COVID-19 variable was also significant and presented the highest regression coefficient (ß = 0.392). The perceived threat of COVID-19 moderated the relationship between social support at work and burnout. CONCLUSION: The perceived threat of COVID-19 helped to explain the degree of burnout in nurses and moderated the relationship between social support at work and burnout. IMPACT: Hospitals should implement strategies to ensure that health emergency situations are not perceived as a threat. In pandemics, the organization should maintain clear, fluid, and regular communication with the nursing staff, which would help increase staff members' confidence and sense of control.

Phytochemical Study of the Genus Salpichroa (Solanaceae), Chemotaxonomic Considerations, and Biological Evaluation in Prostate and Breast Cancer Cells.

Twelve Salpichroa taxa have been phytochemically analyzed. From the aerial parts of S. scandens, four known salpichrolides A, C, I, S, and an unreported withanolide named salpichrolide V (1), were isolated. In S. dependens, S. gayi, S. glandulosa subsp. glandulosa, S. glandulosa subps. weddellii, S. leucantha, S. micrantha, S. microloba, S. proboscidea, S. ramosissima, S. tristis var. tristis, and S. weberbauerii, no withanolides were found. The chemical content of ca. 85% of the Salpichroa taxa is in agreement with molecular studies, which suggest that Salpichroa and Jaborosa, a genus considered morphologically close to Salpichroa, are distant in the systematic of the Solanoideae subfamily. Moreover, the in vitro cytotoxic activity of a set of natural salpichrolides and derivatives was examined against two prostate carcinoma cell lines (PC3 and LNCaP) and two human breast cancer cell lines (MCF-7 and T47D). Several compounds showed moderate activity (IC50  = 64.91 - 29.97 µm).

An overview of nursing in Europe: a SWOT analysis.

This article sets out a global analysis of the weaknesses, threats, strengths and opportunities that define the current situation of nursing in Europe. The nursing profession in Europe is suffering from a crisis of self-efficacy with the syndrome of burnout being one of its consequences. Other weaknesses include shortage of staff, job insecurity, devalued nursing image in society and the lack of recognition of emotional and psychological dimensions of care. The threats to this profession are linked to the lack of prestige and social recognition and to the current economic crisis in Europe. The European economic crisis favours staff shortages and increased European migration flow. The strength of the group lies in the art of caring, which is its defining feature. Primary Care Nursing and Hospital Liaison Nursing demonstrate the great professional adaptability in meeting the needs of the ever-changing society. The European Higher Education Area and the strengthening of the specialties provide opportunities for the nursing profession. Both represent an important progress towards solid professionalism that will give nursing greater visibility. Moreover, nursing must implement strategies to disseminate its activity and emerge from anonymity. Nursing must show society the image it wants to project.

Post-surgery statin use contributes to favorable outcomes in patients with early breast cancer.

BACKGROUND: Statins are a group of lipid-lowering drugs with pleiotropic effects that include, but are not limited to the inhibition of cholesterol synthesis resulting in a wide range of anti-inflammatory, anti-tumor, immunomodulatory, and anti-thrombotic properties. This study aimed to determine the impact of the prior to- or after- breast surgery usage of statins on the tumor prognosis in breast cancer (BC) patients. METHODS: A cohort of patients diagnosed with early invasive ductal BC (n=301) at the Hospital Italiano de Buenos Aires, Argentina, with a minimum follow-up period of 10 years after the surgical procedure were included and stratified according to the time of use of statins and type of statin used. Then, local relapse-free survival (RFS), metastasis-free survival (MFS), bone metastasis-free survival (BMFS), visceral metastasis-free (VMFS), mixed metastasis (bone and visceral)-free survival (mix-MFS) and overall survival (OS) were analyzed. RESULTS: Statins usage after breast surgery was related with lesser metastatic occurrence (p=0.017), lower number of metastatic foci (p=0.034) and fewer dead events (p=0.041), as well as longer MFS (p=0.013) and OS (p=0.027). When stratified by the nature of statins (hydrophilic or lipophilic), only the relatively hydrophilic statin rosuvastatin (ROSU) had an impact on the increase of MFS and OS (p=0.018 and p=0.030, respectively). CONCLUSION: Post-surgery statins usage was associated with increased MFS and OS, with increased benefits of ROSU over simvastatin (SIM) or atorvastatin (ATOR). These results set the rationale for additional studies addressing the use of statins, and particularly, rosuvastatin, to improve the outcome of BC patients.

Role of hydroxymethylglutharyl-coenzyme A reductase in the induction of stem-like states in breast cancer.

PURPOSE: De novo synthesis of cholesterol and its rate-limiting enzyme, 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMGCR), is deregulated in tumors and critical for tumor cell survival and proliferation. However, the role of HMGCR in the induction and maintenance of stem-like states in tumors remains unclear. METHODS: A compiled public database from breast cancer (BC) patients was analyzed with the web application SurvExpress. Cell Miner was used for the analysis of HMGCR expression and statin sensitivity of the NCI-60 cell lines panel. A CRISPRon system was used to induce HMGCR overexpression in the luminal BC cell line MCF-7 and a lentiviral pLM-OSKM system for the reprogramming of MCF-7 cells. Comparisons were performed by two-tailed unpaired t-test for two groups and one- or two-way ANOVA. RESULTS: Data from BC patients showed that high expression of several members of the cholesterol synthesis pathway were associated with lower recurrence-free survival, particularly in hormone-receptor-positive BC. In silico and in vitro analysis showed that HMGCR is expressed in several BC cancer cell lines, which exhibit a subtype-dependent response to statins in silico and in vitro. A stem-like phenotype was demonstrated upon HMGCR expression in MCF-7 cells, characterized by expression of the pluripotency markers NANOG, SOX2, increased CD44 +/CD24low/ -, CD133 + populations, and increased mammosphere formation ability. Pluripotent and cancer stem cell lines showed high expression of HMGCR, whereas cell reprogramming of MCF-7 cells did not increase HMGCR expression. CONCLUSION: HMGCR induces a stem-like phenotype in BC cells of epithelial nature, thus affecting tumor initiation, progression and statin sensitivity.

Adoptive T cell therapy for solid tumors: current landscape and future challenges.

Adoptive cell therapy (ACT) comprises different strategies to enhance the activity of T lymphocytes and other effector cells that orchestrate the antitumor immune response, including chimeric antigen receptor (CAR) T-cell therapy, T-cell receptor (TCR) gene-modified T cells, and therapy with tumor-infiltrating lymphocytes (TILs). The outstanding results of CAR-T cells in some hematologic malignancies have launched the investigation of ACT in patients with refractory solid malignancies. However, certain characteristics of solid tumors, such as their antigenic heterogeneity and immunosuppressive microenvironment, hamper the efficacy of antigen-targeted treatments. Other ACT modalities, such as TIL therapy, have emerged as promising new strategies. TIL therapy has shown safety and promising activity in certain immunogenic cancers, mainly advanced melanoma, with an exciting rationale for its combination with immune checkpoint inhibitors. However, the implementation of TIL therapy in clinical practice is hindered by several biological, logistic, and economic challenges. In this review, we aim to summarize the current knowledge, available clinical results, and potential areas of future research regarding the use of T cell therapy in patients with solid tumors.

Regulation of leptin expression by 17beta-estradiol in human placental cells involves membrane associated estrogen receptor alpha.

The placenta produces a wide number of molecules that play essential roles in the establishment and maintenance of pregnancy. In this context, leptin has emerged as an important player in reproduction. The synthesis of leptin in normal trophoblastic cells is regulated by different endogenous biochemical agents, but the regulation of placental leptin expression is still poorly understood. We have previously reported that 17ß-estradiol (E(2)) up-regulates placental leptin expression. To improve the understanding of estrogen receptor mechanisms in regulating leptin gene expression, in the current study we examined the effect of membrane-constrained E(2) conjugate, E-BSA, on leptin expression in human placental cells. We have found that leptin expression was induced by E-BSA both in BeWo cells and human placental explants, suggesting that E(2) also exerts its effects through membrane receptors. Moreover E-BSA rapidly activated different MAPKs and AKT pathways, and these pathways were involved in E(2) induced placental leptin expression. On the other hand we demonstrated the presence of ERα associated to the plasma membrane of BeWo cells. We showed that E(2) genomic and nongenomic actions could be mediated by ERα. Supporting this idea, the downregulation of ERα level through a specific siRNA, decreased E-BSA effects on leptin expression. Taken together, these results provide new evidence of the mechanisms whereby E(2) regulates leptin expression in placenta and support the importance of leptin in placental physiology.

[Predicting risk of caries in schoolchildren from northwestern Mexico: longitudinal study]. / Predicción de riesgo de caries en escolares del noroeste de México: estudio longitudinal.

OBJECTIVE: To analyze the caries risk through the Bratthall's Cariogram (BC) and the frequency of dental caries in a Mexican northwest children population for 12 months period. MATERIAL AND METHODS: A cohort of 583 scholar children between 6 and 10 years old from Sinaloa state was involved for 12 months period (2007-2008). The Bratthall's Cariogram was used to predict caries risk and the. WHO's criteria were used to obtain the caries index. The caries risk association with clinical variables was analyzed by logistic regression analysis and Sperman's Rho rank correlation test was used to evaluate the correlation between DMFT index and BC. RESULTS: The caries risk increased with respect to age (p < 0.05), the CB identified correctly children for high risk (85%) and low risk (65%) caries for a 12 months period. The baseline values of BC showed a positive correlation with DMFT index (0.86 and p = 0.0001); the diagnostic test evaluation showed the following values: positive predictive value of 87%, negative predictive value of 63%, sensitivity of 93% and specificity of 63%. CONCLUSIONS: The caries risk increased with the age in the studied population. The Bratthall's Cariogram is a useful screening test to evaluate the risk for dental caries at individual and population levels.

Peritumoral adipose tissue promotes lipolysis and white adipocytes browning by paracrine action.

Background: Stromal adipocytes and tumor breast epithelial cells undergo a mutual metabolic adaptation within tumor microenvironment. Therefore, browning and lipolysis occur in cancer associated adipocytes (CAA). However, the paracrine effects of CAA on lipid metabolism and microenvironment remodeling remain poorly understood. Methods: To analyze these changes, we evaluated the effects of factors in conditioned media (CM) derived from explants of human breast adipose tissue from tumor (hATT) or normal (hATN) on morphology, degree of browning, the levels of adiposity, maturity, and lipolytic-related markers in 3T3-L1 white adipocytes by Western blot, indirect immunofluorescence and lipolytic assay. We analyzed subcellular localization of UCP1, perilipin 1 (Plin1), HSL and ATGL in adipocytes incubated with different CM by indirect immunofluorescence. Additionally, we evaluated changes in adipocyte intracellular signal pathways. Results: We found that adipocytes incubated with hATT-CM displayed characteristics that morphologically resembled beige/brown adipocytes with smaller cell size and higher number of small and micro lipid droplets (LDs), with less triglyceride content. Both, hATT-CM and hATN-CM, increased Pref-1, C/EBPß LIP/LAP ratio, PPARγ, and caveolin 1 expression in white adipocytes. UCP1, PGC1α and TOMM20 increased only in adipocytes that were treated with hATT-CM. Also, hATT-CM increased the levels of Plin1 and HSL, while decreased ATGL. hATT-CM modified the subcellular localization of the lipolytic markers, favoring their relative content around micro-LDs and induced Plin1 segregation. Furthermore, the levels of p-HSL, p-ERK and p-AKT increased in white adipocytes after incubation with hATT-CM. Conclusions: In summary, these findings allow us to conclude that adipocytes attached to the tumor could induce white adipocyte browning and increase lipolysis as a means for endocrine/paracrine signaling. Thus, adipocytes from the tumor microenvironment exhibit an activated phenotype that could have been induced not only by secreted soluble factors from tumor cells but also by paracrine action from other adipocytes present in this microenvironment, suggesting a "domino effect".

BRAF Inhibitors in Metastatic Colorectal Cancer and Mechanisms of Resistance: A Review of the Literature.

Metastatic colorectal cancer (mCRC) with mutated BRAF exhibits distinct biological and molecular features that set it apart from other subtypes of CRC. Current standard treatment for these tumors involves a combination of chemotherapy (CT) and VEGF inhibitors. Recently, targeted therapy against BRAF and immunotherapy (IT) for cases with microsatellite instability (MSI) have been integrated into clinical practice. While targeted therapy has shown promising results, resistance to treatment eventually develops in a significant portion of responsive patients. This article aims to review the available literature on mechanisms of resistance to BRAF inhibitors (BRAFis) and potential therapeutic strategies to overcome them.

Current Landscape of Immunotherapy for Advanced Sarcoma.

There is substantial heterogeneity between different subtypes of sarcoma regarding their biological behavior and microenvironment, which impacts their responsiveness to immunotherapy. Alveolar soft-part sarcoma, synovial sarcoma and undifferentiated pleomorphic sarcoma show higher immunogenicity and better responses to checkpoint inhibitors. Combination strategies adding immunotherapy to chemotherapy and/or tyrosine-kinase inhibitors globally seem superior to single-agent schemes. Therapeutic vaccines and different forms of adoptive cell therapy, mainly engineered TCRs, CAR-T cells and TIL therapy, are emerging as new forms of immunotherapy for advanced solid tumors. Tumor lymphocytic infiltration and other prognostic and predictive biomarkers are under research.

Human periprostatic adipose tissue: its influence on prostate cancer cells.

BACKGROUND/AIMS: Adipose microenvironment is involved in signaling pathways that influence prostate cancer (PCa) progression. However, the role of human periprostatic adipose tissue (PPAT) from patients with benign prostatic hyperplasia (BPH) has not been studied and compared to that of PPAT from PCa patients. The aim of this paper was to investigate the influence of factors derived from both PPATs on the behavior of androgen-dependent and castration resistant PCa cells. METHODS: PPAT conditioned media (CM) were obtained from tissue samples from patients with clinically primary PCa (TPPAT) or BPH (BPPAT). Cell adhesion, proliferation, migration and metalloproteinase expression were evaluated following exposure of LNCaP (androgen dependent) and PC3 (androgen independent) prostate cancer cell lines to BPPAT or TPPAT CM. RESULTS: Proliferation or motility of LNCaP or PC3 cells were not significantly affected by TPPAT or BPPAT CM. The number of LNCaP but not PC3 cells attached to components of TPPAT CM significantly decreased compared to cells attached to BPPAT CM. PPAT produced and released pro-MMP-9. Zymograms demonstrated that TPPAT CM induced a significant increase in pro-MMP-9 activity compared to BPPAT CM in LNCaP cells but not in PC3 cells. CONCLUSIONS: We conclude that TPPAT released factors, such as pro-MMP-9, could induce the invasive capacity of LNCaP cells and speculate that PPAT derived factors could, in the early stages of prostate cancer, modulate disease progression.

Periprostatic Adipose Tissue Microenvironment: Metabolic and Hormonal Pathways During Prostate Cancer Progression.

The periprostatic adipose tissue (PPAT) is a site of invasion of prostate cancer (PCa) and is part of the microenvironment. It was shown that PPAT secretes factors and fatty acids (FAs) that alter the microenvironment of the PCa. The PPAT secretome of patients with PCa-T3 stage (PPAT-T3) has a metabolic profile enriched in several pathways related to energy production, indicating a greater energy requirement by the tumor, when compared to that of patients in the PCa-T2 stage (PPAT-T2). PPAT-T3 also shows enrichment in pathways related to hormone response, polyamine synthesis, and control of protein synthesis, through amino acid, RNA, and nucleotide metabolism. PPAT-T2 and PPAT-BPH secretomes have less complex metabolic profile, both related with energy balance, while PPAT-BPH has hormone response through insulin pathway. Undoubtedly, a deeper characterization of the human PPAT will lead to a better understanding of the disease and possibly allow new stratification factors and the design of a specific therapy that targets crucial components of the tumor microenvironment as another way to treat or control the disease.

Renal peritumoral adipose tissue undergoes a browning process and stimulates the expression of epithelial-mesenchymal transition markers in human renal cells.

Tumor cells can interact with neighboring adipose cells and adipocyte dedifferentiation appears to be an important aspect of tumorigenesis. We evaluated the size of adipocytes in human adipose explants from normal (hRAN) and kidney cancer (hRAT); changes in the expression of WAT and BAT/beige markers in hRAN and hRAT; the expression of epithelial-mesenchymal transition (EMT) cell markers in human kidney tumor (786-O, ACHN and Caki-1); and non-tumor (HK-2) epithelial cell lines incubated with the conditioned media (CMs) of hRAN and hRAT. We observed that hRAT adipocytes showed a significantly minor size compared to hRAN adipocytes. Also, we observed that both Prdm16 and Tbx1 mRNA and the expression of UCP1, TBX1, PPARγ, PCG1α, c/EBPα LAP and c/EBPα LIP was significantly higher in hRAT than hRAN. Finally, we found an increase in vimentin and N-cadherin expression in HK-2 cells incubated for 24 h with hRAT-CMs compared to hRAN- and control-CMs. Furthermore, desmin and N-cadherin expression also increased significantly in 786-O when these cells were incubated with hRAT-CMs compared to the value observed with hRAN- and control-CMs. We observed a significant decrease in E-cadherin expression in the ACHN cell line incubated with hRAT-CMs versus hRAN- and control-CMs. However, we did not observe changes in E-cadherin expression in HK-2, 786-O or Caki-1. The results obtained, together with the results previously published by our group, allow us to conclude that perirenal white adipose tissue browning contributes to tumor development in kidney cancer. In addition, hRAT-CMs increases the expression of mesenchymal markers in renal epithelial cells, which could indicate a regulation of EMT due to this adipose tissue.

Classical membrane progesterone receptors in murine mammary carcinomas: agonistic effects of progestins and RU-486 mediating rapid non-genomic effects.

In this article, we demonstrate the expression of functional progesterone binding sites at the cell membrane in murine mammary carcinomas that are stimulated by progestins and inhibited by antiprogestins. Using confocal immunofluorescence, ligand binding and cell compartment-specific western blots, we were able to identify the presence of the classical progesterone receptors. Medroxyprogesterone acetate (MPA) and RU-486 (1 × 10(-11) and 1 × 10(-8) M) behaved as agonists activating extracellular signal-regulated kinases (ERKs) and progestin-regulated proteins, except for Cyclin D1 and Tissue factor which failed to increase with 1 × 10(-8) M RU-486, an experimental condition that allows PR to bind DNA. These results predicted a full agonist effect at low concentrations of RU-486. Accordingly, at concentrations lower than 1 × 10(-11) M, RU-486 increased cell proliferation in vitro. This effect was abolished by incubation with the ERK kinase inhibitor PD 98059 or by OH-tamoxifen. In vivo, at a daily dose of 1.2 µg/kg body weight RU-486 increased tumor growth, whereas at 12 mg/kg induces tumor regression. Our results indicate that low concentrations of MPA and RU-486 induce similar agonistic non-genomic effects, whereas RU-486 at higher concentrations may inhibit cell proliferation by genomic-induced effects. This suggests that RU-486 should be therapeutically administered at doses high enough to guarantee its genomic inhibitory effect.