Maria Loreto Bravo

Paclitaxel-PHBV nanoparticles and their toxicity to endometrial and primary ovarian cancer cells

This report is an integrated study to include the molecular simulation, physicochemical characterization and biological analysis of a paclitaxel-loaded PHBV nanoparticle that demonstrates uptake, release and cytotoxicity in cancer cell lines. Taking this nanoparticle one step closer to its use in a clinical setting, we demonstrate that it causes significant cell death in primary cultures of stage IIIc serous ovarian cancer cells isolated from six patients. Molecular simulations revealed a high affinity of paclitaxel for the water-polymer interface, thus the drug is delivered only when the polymer near it is degraded. The Fourier transform infrared spectroscopy suggests the formation of a short-lived crystalline phase, also observed in the CG simulations, and transmission electron microscopy revealed branched structures on the surface of particles, which disappeared after 4 days. Biological analyses indicated that these particles have a 48-h window of toxicity protection, allowing for the endocytosis of the particle by the cells; this finding was corroborated by confocal microscopy and flow cytometry. The low cost to synthesize PHBV using microorganisms and the potential chemical modifications of the polymer make it attractive for inexpensive, large-scale pharmaceutical production.

Metformin, at Concentrations Corresponding to the Treatment of Diabetes, Potentiates the Cytotoxic Effects of Carboplatin in Cultures of Ovarian Cancer Cells

The use of the type 2 diabetics drug metformin has been correlated with enhanced progression-free survival in ovarian cancer. The literature has speculated that this enhancement is due to the high concentration of metformin directly causing cancer cell death. However, this explanation does not fit with clinical data reporting that the women exposed to constant micromolar concentrations of metformin, as present in the treatment of diabetes, respond better to chemotherapy. Herein, our aim was to examine whether micromolar concentrations of metformin alone could bring about cancer cell death and whether micromolar metformin could increase the cytotoxic effect of commonly used chemotherapies in A2780 and SKOV3 cell lines and primary cultured cancer cells isolated from the peritoneal fluid of patients with advanced ovarian cancer. Our results in cell lines demonstrate that no significant loss of viability or change in cell cycle was observed with micromolar metformin alone; however, we observed cytotoxicity with micromolar metformin in combination with chemotherapy at concentrations where the chemotherapy alone produced no loss in viability. We demonstrate that previous exposure and maintenance of metformin in conjunction with carboplatin produces a synergistic enhancement in cytotoxicity of A2780 and SKOV3 cells (55% and 43%, respectively). Furthermore, in 5 (44%) of the 11 ovarian cancer primary cultures, micromolar metformin improved the cytotoxic response to carboplatin but not paclitaxel or doxorubicin. In conclusion, we present data that support the need for a clinical study to evaluate the adjuvant maintenance or prescription of currently approved doses of metformin during the chemotherapeutic treatment of ovarian cancer.

Platelets enhance tissue factor protein and metastasis initiating cell markers, and act as chemoattractants increasing the migration of ovarian cancer cells

BackgroundAn increase in circulating platelets, or thrombocytosis, is recognized as an independent risk factor of bad prognosis and metastasis in patients with ovarian cancer; however the complex role of platelets in tumor progression has not been fully elucidated. Platelet activation has been associated with an epithelial to mesenchymal transition (EMT), while Tissue Factor (TF) protein expression by cancer cells has been shown to correlate with hypercoagulable state and metastasis. The aim of this work was to determine the effect of platelet-cancer cell interaction on TF and “Metastasis Initiating Cell (MIC)” marker levels and migration in ovarian cancer cell lines and cancer cells isolated from the ascetic fluid of ovarian cancer patients.MethodsWith informed patient consent, ascitic fluid isolated ovarian cancer cells, cell lines and ovarian cancer spheres were co-cultivated with human platelets. TF, EMT and stem cell marker levels were determined by Western blotting, flow cytometry and RT-PCR. Cancer cell migration was determined by Boyden chambers and the scratch assay.ResultsThe co-culture of patient-derived ovarian cancer cells with platelets causes: 1) a phenotypic change in cancer cells, 2) chemoattraction and cancer cell migration, 3) induced MIC markers (EMT/stemness), 3) increased sphere formation and 4) increased TF protein levels and activity.ConclusionsWe present the first evidence that platelets act as chemoattractants to cancer cells. Furthermore, platelets promote the formation of ovarian cancer spheres that express MIC markers and the metastatic protein TF. Our results suggest that platelet-cancer cell interaction plays a role in the formation of metastatic foci.

Progesterone promotes focal adhesion formation and migration in breast cancer cells through induction of protease-activated receptor-1

Progesterone and progestins have been demonstrated to enhance breast cancer cell migration, although the mechanisms are still not fully understood. The protease-activated receptors (PARs) are a family of membrane receptors that are activated by serine proteases in the blood coagulation cascade. PAR1 (F2R) has been reported to be involved in cancer cell migration and overexpressed in breast cancer. We herein demonstrate that PAR1 mRNA and protein are upregulated by progesterone treatment of the breast cancer cell lines ZR-75 and T47D. This regulation is dependent on the progesterone receptor (PR) but does not require PR phosphorylation at serine 294 or the PR proline-rich region mPRO. The increase in PAR1 mRNA was transient, being present at 3  h and returning to basal levels at 18  h. The addition of a PAR1-activating peptide (aPAR1) to cells treated with progesterone resulted in an increase in focal adhesion (FA) formation as measured by the cellular levels of phosphorylated FA kinase. The combined but not individual treatment of progesterone and aPAR1 also markedly increased stress fiber formation and the migratory capacity of breast cancer cells. In agreement with in vitro findings, data mining from the Oncomine platform revealed that PAR1 expression was significantly upregulated in PR-positive breast tumors. Our observation that PAR1 expression and signal transduction are modulated by progesterone provides new insight into how the progestin component in hormone therapies increases the risk of breast cancer in postmenopausal women.

Progesterone utilizes distinct membrane pools of tissue factor to increase coagulation and invasion and these effects are inhibited by TFPI

Tissue factor (TF) serving as the receptor for coagulation factor VII (FVII) initiates the extrinsic coagulation pathway. We previously demonstrated that progesterone increases TF, coagulation and invasion in breast cancer cell lines. Herein, we investigated if tissue factor pathway inhibitor (TFPI) could down‐regulate progesterone‐increased TF activity in these cells. Classically, TFPI redistributes TF‐FVII‐FX‐TFPI in an inactive quaternary complex to membrane associated lipid raft regions. Herein, we demonstrate that TF increased by progesterone is localized to the heavy membrane fraction, despite progesterone‐increased coagulation originating almost exclusively from lipid raft domains, where TF levels are extremely low. The progesterone increase in coagulation is not a rapid effect, but is progesterone receptor (PR) dependent and requires protein synthesis. Although a partial relocalization of TF occurs, TFPI does not require the redistribution to lipid rafts to inhibit coagulation or invasion. Inhibition by TFPI and anti‐TF antibodies in lipid raft membrane fractions confirmed the dependence on TF for progesterone‐mediated coagulation. Through the use of pathway inhibitors, we further demonstrate that the TF up‐regulated by progesterone is not coupled to the progesterone increase in TF‐mediated coagulation. However, the progesterone up‐regulated TF protein may be involved in progesterone‐mediated breast cancer cell invasion, which TFPI also inhibits. J. Cell. Physiol. 226: 3278–3285, 2011.

2-Methoxyestradiol Inhibits Progesterone-Dependent Tissue Factor Expression and Activity in Breast Cancer Cells

Abstract2-Methoxyestradiol (2ME) is an endogenous metabolite of 17β-estradiol with antiangiogenic and antitumor properties, although its mechanisms of action remain unclear. Progestins in hormone replacement therapy increase the risk of breast cancer. Progesterone also enhances the procoagulant activity and invasive potential of progesterone receptor (PR)-positive breast cancer cell lines, an effect largely mediated by induction of tissue factor (TF), the cellular activator of the coagulation cascade. Here we show that 2ME abrogates the induction TF expression in progesterone-treated breast cancer cells via a mechanism that does not involve the estrogen receptor. Instead, we demonstrate that by selectively antagonizing ERK1/2 signaling in breast cancer cells, 2ME limits the transactivation potential of ligand-bound PR and inhibits the expression of endogenous progesterone targets, such as TF and signal transducer and activator of transcription 5. We further demonstrate that 2ME can alter the phosphorylation status of PR. Thus, 2ME prevents progesterone-dependent increase in breast cancer cell invasiveness and procoagulant activity by uncoupling PR from the ERK1/2 signal transduction pathway.

Diabetic concentrations of metformin inhibit platelet-mediated ovarian cancer cell progression

Clinical studies have suggested a survival benefit in ovarian cancer patients with type 2 diabetes mellitus taking metformin, however the mechanism by which diabetic concentrations of metformin could deliver this effect is still poorly understood. Platelets not only represent an important reservoir of growth factors and angiogenic regulators, they are also known to participate in the tumor microenvironment implicated in tumor growth and dissemination. Herein, we investigated if diabetic concentrations of metformin could impinge upon the previously reported observation that platelet induces an increase in the tube forming capacity of endothelial cells (angiogenesis) and upon ovarian cancer cell aggressiveness. We demonstrate that metformin inhibits the increase in angiogenesis brought about by platelets in a mechanism that did not alter endothelial cell migration. In ovarian cancer cell lines and primary cultured cancer cells isolated from the ascitic fluid of ovarian cancer patients, we assessed the effect of combinations of platelets and metformin upon angiogenesis, migration, invasion and cancer sphere formation. The enhancement of each of these parameters by platelets was abrogated by the present of metformin in the vast majority of cancer cell cultures tested. Neither metformin nor platelets altered proliferation; however, metformin inhibited the increase in phosphorylation of focal adhesion kinase induced by platelets. We present the first evidence suggesting that concentrations of metformin present in diabetic patients may reduce the actions of platelets upon both endothelial cells and cancer cell survival and dissemination.

Potencial herramienta en la personalización del tratamiento oncológico: Casos clínicos

Our laboratory has implemented an in vitro assay to estimate the response to chemotherapy in ovarian cancer cells pertaining to individual patients. In two selected patients, we determined the correlation between an in vitro assay of cells from suspected ovarian cancer ascites, with the clinical chemotherapy response. Cancer cells isolated from peritoneal fluid with suspected ovarian cancer were tested for cytotoxicity with corresponding chemotherapy regimens. Circulating Cal25 levels and attending physician consultation determined clinical course and response to chemotherapy. The in vitro assay result correlated with Cal25 levels, progression free survival and attending physician evaluation. The assay predicted correctly the failure of two successive chemotherapy regimes in the first patient, while predicting a favorable clinical response in the second subject.

Structural and functional identification of vasculogenic mimicry in vitro

Vasculogenic mimicry (VM) describes a process by which cancer cells establish an alternative perfusion pathway in an endothelial cell-free manner. Despite its strong correlation with reduced patient survival, controversy still surrounds the existence of an in vitro model of VM. Furthermore, many studies that claim to demonstrate VM fail to provide solid evidence of true hollow channels, raising concerns as to whether actual VM is actually being examined. Herein, we provide a standardized in vitro assay that recreates the formation of functional hollow channels using ovarian cancer cell lines, cancer spheres and primary cultures derived from ovarian cancer ascites. X-ray microtomography 3D-reconstruction, fluorescence confocal microscopy and dye microinjection conclusively confirm the existence of functional glycoprotein-rich lined tubular structures in vitro and demonstrate that many of structures reported in the literature may not represent VM. This assay may be useful to design and test future VM-blocking anticancer therapies.

Patient inflammatory status and CD4+/CD8+ intraepithelial tumor lymphocyte infiltration are predictors of outcomes in high-grade serous ovarian cancer

BACKGROUND High-grade serous ovarian cancer (HGSOC) is the most prevalent and aggressive histologic type of ovarian cancer. To date, there are no reliable biomarkers to effectively predict patient prognosis. Studies have demonstrated inflammation and tumor infiltrating lymphocytes (TILs) correlate with a bad and good prognosis, respectively. Here, we sought to evaluate systemic inflammation and TILs as early prognostic markers of survival. METHODS Neutrophil-to-lymphocyte ratio (NLR) and serum Lactate Dehydrogenase (LDH) were used as indicators of systemic inflammation. NLR, serum LDH, tumor infiltrating lymphocytes (TILs), PDL1 and quality of debulking surgery were evaluated as determinants of progression-free survival (PFS) and overall survival (OS) in a cohort of 128 HGSOC patients. RESULTS Initial univariate analysis showed that systemic inflammation measures (NLR and serum LDH), debulking surgery, and intra-epithelial TILs have a significant impact on both PFS and OS. After adjustment for several variables, multivariate analyses confirmed intraepithelial CD4+ T-cells, systemic inflammation measures, PDL1 and debulking surgery as determinants of better OS and PFS. CONCLUSIONS Systemic inflammation and TILs are early determinants of OS in HGSOC. Other variables such as the quality of debulking surgery and PDL1 also improve survival of patients. Regarding TIL sub-populations, intraepithelial CD4+ cells are associated to an increase in both PFS and OS. We also confirmed previous reports that demonstrate intraepithelial CD8+ cells correlate with an increase on PFS in ovarian cancer. A combined score using systemic inflammation and TILs may be of prognostic value for HGSOC patients.