Mifepristone improves chemo-radiation response in glioblastoma xenografts

The Role of Paxillin Aberrant Expression in Cancer and Its Potential as a Target for Cancer Therapy

Paxillin is a multi-domain adaptor protein. As an important member of focal adhesion (FA) and a participant in regulating cell movement, paxillin plays an important role in physiological processes such as nervous system development, embryonic development, and vascular development. However, increasing evidence suggests that paxillin is aberrantly expressed in many cancers. Many scholars have also recognized that the abnormal expression of paxillin is related to the prognosis, metastases, invasion, survival, angiogenesis, and other aspects of malignant tumors, suggesting that paxillin may be a potential cancer therapeutic target. Therefore, the study of how aberrant paxillin expression affects the process of tumorigenesis and metastasis will help to develop more efficacious antitumor drugs. Herein, we review the structure of paxillin and its function and expression in tumors, paying special attention to the multifaceted effects of paxillin on tumors, the mechanism of tumorigenesis and progression, and its potential role in tumor therapy. We also hope to provide a reference for the clinical prognosis and development of new tumor therapeutic targets.

Progesterone Receptor Together with PKCα Expression as Prognostic Factors for Astrocytomas Malignancy

Introduction

Astrocytomas are the most common and aggressive primary brain tumors, and they are classified according to the degree of malignancy on a scale of I to IV, in which grade I is the least malignant and grade IV the highest. Many factors are related to astrocytomas progression as progesterone receptor (PR), whose transcriptional activity could be regulated by phosphorylation by protein kinase C alpha (PKCα) at the residue Ser400. Our aim was to investigate if PR phosphorylation together with PKCα expression could be used as a prognostic factor for astrocytomas malignancy.

Methods

By immunofluorescence, we detected the content of PKCα, PR and its phosphorylation at Ser400 in 46 biopsies from Mexican patients with different astrocytoma malignancy grades; by bioinformatic tools using TCGA data, we evaluated the expression of PR and PKCα mRNA according to astrocytoma malignancy grades. For all statistical analyses, significance was p<0.05.

Results

We detected a positive correlation between the tumor grade and the content of PKCα, PR and its phosphorylation at Ser400, as well as the intracellular colocalization of these proteins. Interestingly, using an in silico assay, we found that the PR and PKCα expression at mRNA level has an inverse ratio with astrocytomas tumor grade.

Discussion

These results indicate that PR and its phosphorylation at Ser400 site, as well as PKCα and their colocalization, could be considered as possible malignancy biomarkers for astrocytomas grades I–IV.

Mifepristone Repurposing in Treatment of High-Grade Gliomas

Glioma is the most common and aggressive primary tumor of the central nervous system. The standard treatment for malignant gliomas is surgery followed by chemoradiotherapy. Unfortunately, this treatment has not produced an adequate patient response, resulting in a median survival time of 12–15 months and a 5-year overall survival of <5%. Although new strategies have been sought to enhance patient response, no significant increase in the global survival of glioma patients has been achieved. The option of developing new drugs implies a long and costly process, making drug repurposing a more practical alternative for improving glioma treatment. In the last few years, researchers seeking more effective cancer therapy have pursued the possibility of using anti-hormonal agents, such as mifepristone. The latter drug, an antagonist for progesterone and glucocorticoid receptors, has several attractive features: anti-tumor activity, low cytotoxicity to healthy cells, and modulation of the chemosensitivity of several cancer cell lines in vitro. Hence, the addition of mifepristone to temozolomide-based glioblastoma chemotherapy may lead to a better patient response. The mechanisms by which mifepristone enhances glioma treatment are not yet known. The current review aims to discuss the potential role of mifepristone as an adjuvant drug for the treatment of high-grade gliomas.

Cancer and Stress: Does It Make a Difference to the Patient When These Two Challenges Collide?

Simple Summary

Head and neck cancers are the sixth most common cancer in the world. The burden of the disease has remained challenging over recent years despite the advances in treatments of other malignancies. The very use of the word malignancy brings about a stress response in almost all adult patients. Being told you have a tumour is not a word anyone wants to hear. We have embarked on a study which will investigate the effect of stress pathways on head and neck cancer patients and which signalling pathways may be involved. In the future, this will allow clinicians to better manage patients with head and neck cancer and reduce the patients’ stress so that this does not add to their tumour burden.

Abstract

A single head and neck Cancer (HNC) is a globally growing challenge associated with significant morbidity and mortality. The diagnosis itself can affect the patients profoundly let alone the complex and disfiguring treatment. The highly important functions of structures of the head and neck such as mastication, speech, aesthetics, identity and social interactions make a cancer diagnosis in this region even more psychologically traumatic. The emotional distress engendered as a result of functional and social disruption is certain to negatively affect health-related quality of life (HRQoL). The key biological responses to stressful events are moderated through the combined action of two systems, the hypothalamus–pituitary–adrenal axis (HPA) which releases glucocorticoids and the sympathetic nervous system (SNS) which releases catecholamines. In acute stress, these hormones help the body to regain homeostasis; however, in chronic stress their increased levels and activation of their receptors may aid in the progression of cancer. Despite ample evidence on the existence of stress in patients diagnosed with HNC, studies looking at the effect of stress on the progression of disease are scarce, compared to other cancers. This review summarises the challenges associated with HNC that make it stressful and describes how stress signalling aids in the progression of cancer. Growing evidence on the relationship between stress and HNC makes it paramount to focus future research towards a better understanding of stress and its effect on head and neck cancer.

Mifepristone as a Potential Therapy to Reduce Angiogenesis and P-Glycoprotein Associated With Glioblastoma Resistance to Temozolomide

Glioblastoma, the most common primary central nervous system tumor, is characterized by extensive vascular neoformation and an area of necrosis generated by rapid proliferation. The standard treatment for this type of tumor is surgery followed by chemotherapy based on temozolomide and radiotherapy, resulting in poor patient survival. Glioblastoma is known for strong resistance to treatment, frequent recurrence and rapid progression. The aim of this study was to evaluate whether mifepristone, an antihormonal agent, can enhance the effect of temozolomide on C6 glioma cells orthotopically implanted in Wistar rats. The levels of the vascular endothelial growth factor (VEGF), and P-glycoprotein (P-gp) were examined, the former a promoter of angiogenesis that facilitates proliferation, and the latter an efflux pump transporter linked to drug resistance. After a 3-week treatment, the mifepristone/temozolomide regimen had decreased the level of VEGF and P-gp and significantly reduced tumor proliferation (detected by PET/CT images based on 18F-fluorothymidine uptake). Additionally, mifepristone proved to increase the intracerebral concentration of temozolomide. The lower level of O6-methylguanine-DNA-methyltransferase (MGMT) (related to DNA repair in tumors) previously reported for this combined treatment was herein confirmed. After the mifepristone/temozolomide treatment ended, however, the values of VEGF, P-gp, and MGMT increased and reached control levels by 14 weeks post-treatment. There was also tumor recurrence, as occurred when administering temozolomide alone. On the other hand, temozolomide led to 100% mortality within 26 days after beginning the drug treatment, while mifepristone/temozolomide enabled 70% survival 60–70 days and 30% survived over 100 days, suggesting that mifepristone could possibly act as a chemo-sensitizing agent for temozolomide.

Liposomes Co-Encapsulating Cisplatin/Mifepristone Improve the Effect on Cervical Cancer: In Vitro and In Vivo Assessment

Cervical cancer is usually diagnosed in the later stages despite many campaigns for early detection and continues to be a major public health problem. The standard treatment is cisplatin-based chemotherapy plus radiotherapy, but patient response is far from ideal. In the research for new drugs that enhance the activity of cisplatin, different therapeutic agents have been tested, among them the antiprogestin mifepristone. Nevertheless, the efficacy of cisplatin is limited by its low specificity for tumor tissue, which causes severe side effects. Additionally, cervical tumors often become drug resistant. These problems could possibly be addressed by the use of liposome nanoparticles to encapsulate drugs and deliver them to the target. The aim of this study was to prepare liposome nanoparticles that co-encapsulate cisplatin and mifepristone, evaluate their cytotoxicity against HeLa cells and in vivo with subcutaneous inoculations of xenografts in nu/nu mice, and examine some plausible mechanisms of action. The liposomes were elaborated by the reverse-phase method and characterized by physicochemical tests. The nanoparticles had a mean particle size of 109 ± 5.4 nm and a Zeta potential of -38.7 ± 1.2 mV, the latter parameter indicating a stable formulation. These drug-loaded liposomes significantly decreased cell viability in vitro and tumor size in vivo, without generating systemic toxicity in the animals. There was evidence of cell cycle arrest and increased apoptosis. The promising results with the co-encapsulation of cisplatin/mifepristone warrant further research.

The Effect of Glucocorticoids on Angiogenesis in the Treatment of Solid Tumors

Glucocorticoids are steroid hormones produced by the adrenal cortex in a circadian manner and they participate in many physiological and pathological processes. Synthetic glucocorticoids have been universally applied to treat inflammatory diseases and immune disorders. Due to their angiostatic property, glucocorticoids are often added to regimens for cancer treatment. In the current review, we summarize how glucocorticoids influence angiogenesis in common solid tumors based on literature from the last ten years. Usage of glucocorticoids can be a double-edged sword in the treatment of some malignancies. There are still unanswered questions about the role of glucocorticoids in the treatment regimens of some common cancers. Therefore, we suggest prudent and restricted administration of glucocorticoids to treat solid tumors.

Tibolone Effects on Human Glioblastoma Cell Lines

BACKGROUND

Ovarian steroid hormones are involved in modulating the growth of glioblastomas (the most common, aggressive, and lethal brain tumor) through the interaction with their intracellular receptors. Activation of sex hormone receptors is involved in glioblastomas progression. Tibolone (TIB) is a selective tissue estrogenic activity regulator widely prescribed to treat menopausal symptoms and to prevent bone lost. The effects of TIB on the growth of glioblastoma are unknown.

AIM OF THE STUDY

To evaluate the effects of TIB on cell number, migration, and invasion of two derived human glioblastoma cell lines (U251 MG and U87), as well as the role of this steroid in estrogen and progesterone receptors activity and content.

METHODS

U251-MG and U87 human glioblastoma cell lines were grown with different doses of TIB. The number of cells was determined and migration and invasion tests were carried out. Protein expression was performed by Western blot.

RESULTS

We observed that TIB (10 nM) increased the number of cells by inducing proliferation with no effects on cell migration or invasion. The increase in cell proliferation induced by TIB was blocked by estrogen (ERs) or progesterone receptor (PRs) antagonists, ICI 182, 780 and RU 486, suggesting that these receptors mediate proliferating actions of TIB; TIB also modified the content of ERs and PRs by increasing ER-α, ER-β, and PR-B, while decreased PR-A.

CONCLUSION

Our results suggest that TIB increases cell number and proliferation of human glioblastoma cells through the regulation of ERs and PRs actions and content.

Mifepristone Overcomes Tumor Resistance to Temozolomide Associated with DNA Damage Repair and Apoptosis in an Orthotopic Model of Glioblastoma

The standard treatment for glioblastoma multiforme (GBM) is surgery followed by chemo/radiotherapy. A major limitation on patient improvement is the high resistance of tumors to drug treatment, likely responsible for their subsequent recurrence and rapid progression. Therefore, alternatives to the standard therapy are necessary. The aim of the present study was to evaluate whether mifepristone, an antihormonal agent, has a synergistic effect with temozolomide (used in standard therapy for gliomas). Whereas the mechanism of temozolomide involves damage to tumor DNA leading to apoptosis, tumor resistance is associated with DNA damage repair through the O⁶-methylguanine-DNA-methyltransferase (MGMT) enzyme. Temozolomide/mifepristone treatment, herein examined in Wistar rats after orthotopically implanting C6 glioma cells, markedly reduced proliferation. This was evidenced by a decreased level of the following parameters: a proliferation marker (Ki-67), a tumor growth marker (¹⁸F-fluorothymidine uptake, determined by PET/CT images), and the MGMT enzyme. Increased apoptosis was detected by the relative expression of related proteins, (e.g. Bcl-2 (B-cell lymphoma 2), Bax (bcl-2-like protein 4) and caspase-3). Thus, greater apoptosis of tumor cells caused by their diminished capacity to repair DNA probably contributed significantly to the enhanced activity of temozolomide. The results suggest that mifepristone could possibly act as a chemo-sensitizing agent for temozolomide during chemotherapy for GBM.

Selective glucocorticoid receptor-activating adjuvant therapy in cancer treatments

Although adverse effects and glucocorticoid resistance cripple their chronic use, glucocorticoids form the mainstay therapy for acute and chronic inflammatory disorders, and play an important role in treatment protocols of both lymphoid malignancies and as adjuvant to stimulate therapy tolerability in various solid tumors. Glucocorticoid binding to their designate glucocorticoid receptor (GR), sets off a plethora of cell-specific events including therapeutically desirable effects, such as cell death, as well as undesirable effects, including chemotherapy resistance, systemic side effects and glucocorticoid resistance. In this context, selective GR agonists and modulators (SEGRAMs) with a more restricted GR activity profile have been developed, holding promise for further clinical development in anti-inflammatory and potentially in cancer therapies. Thus far, the research into the prospective benefits of selective GR modulators in cancer therapy limped behind. Our review discusses how selective GR agonists and modulators could improve the therapy regimens for lymphoid malignancies, prostate or breast cancer. We summarize our current knowledge and look forward to where the field should move to in the future. Altogether, our review clarifies novel therapeutic perspectives in cancer modulation via selective GR targeting.

Antihormonal agents as a strategy to improve the effect of chemo-radiation in cervical cancer: in vitro and in vivo study

Background

Over the past few years, the concurrent use of cisplatin-based chemotherapy and radiation therapy has dramatically improved the local response and increased overall survival in early-stage cervical cancer. However, for the advanced stages of the disease this standard treatment has proved insufficient. We investigated the capacity of Mifepristone and ICI 182,780, which are anti-progestin and anti-estrogen drugs, respectively, to act as chemo-radiosensitizing agents in cervical cancer cells and cervix xenografts.

Methods

The effect of chemo-radiation alone or combined with Mifepristone or ICI 182,780 was evaluated in HeLa cells and with tumor growth in cervix xenografts. After concomitant chemo-radiotherapy, the effect of each of these antihormonal agents on apoptosis (determined by Annexing V assay) and the cell cycle phases were determined by flow cytometry. The expression of angiogenic factor VEGF in tumor samples was determined using quantitative RT-PCR analysis of VEGF gene expression.

Results

Compared to radiation alone or radiation/cisplatin therapy, there was significantly higher cytotoxicity and a greater antitumoral effect with the combined application of radiation/cisplatin and Mifepristone or ICI 182,780. Analyses of the apoptosis and cell cycle demonstrated changes only with ICI, not with Mifepristone, when was applied in combination with radiation/cisplatin. The analysis of VEGF mRNA expression levels in tumors at the end of the study demonstrated a significant inhibition, compared to radiation only or the radiation/cisplatin treatment, after concurrent chemo-radiotherapy and each one of the antihormonal drugs.

Conclusion

Mifepristone and ICI 182,780 may be potentially promising chemo-radiosensitizing compounds to be used in combination with ionizing irradiation and cisplatin in the treatment of patients with advanced cervical cancer.

Systems pharmacology of mifepristone (RU486) reveals its 47 hub targets and network: comprehensive analysis and pharmacological focus on FAK-Src-Paxillin complex

Mifepristone (RU486), a synthetic steroid compound used as an abortifacient drug, has received considerable attention to its anticancer activity recently. To explore the possibility of using mifepristone as a cancer metastasis chemopreventive, we performed a systems pharmacology analysis of mifepristone-related molecules in the present study. Data were collected by using Natural Language Processing (NLP) and 513 mifepristone-related genes were dug out and classified functionally using a gene ontology (GO) hierarchy, followed by KEGG pathway enrichment analysis. Potential signal pathways and targets involved in cancer were obtained by integrative network analysis. Total thirty-three proteins were involved in focal adhesion-the key signaling pathway associated with cancer metastasis. Molecular and cellular assays further demonstrated that mifepristone had the ability to prevent breast cancer cells from migration and interfere with their adhesion to endothelial cells. Moreover, mifepristone inhibited the expression of focal adhesion kinase (FAK), paxillin, and the formation of FAK/Src/Paxillin complex, which are correlated with cell adhesion and migration. This study set a good example to identify chemotherapeutic potential seamlessly from systems pharmacology to cellular pharmacology, and the revealed hub genes may be the promising targets for cancer metastasis chemoprevention.

Progesterone induces the growth and infiltration of human astrocytoma cells implanted in the cerebral cortex of the rat

Progesterone (P4) promotes cell proliferation in several types of cancer, including brain tumors such as astrocytomas, the most common and aggressive primary intracerebral neoplasm in humans. In this work, we studied the effects of P4 and its intracellular receptor antagonist, RU486, on growth and infiltration of U373 cells derived from a human astrocytoma grade III, implanted in the motor cortex of adult male rats, using two treatment schemes. In the first one, fifteen days after cells implantation, rats were daily subcutaneously treated with vehicle (propylene glycol, 160  μ L), P4 (1 mg), RU486 (5 mg), or P4 + RU486 (1 mg and 5 mg, resp.) for 21 days. In the second one, treatments started 8 weeks after cells implantation and lasted for 14 days. In both schemes we found that P4 significantly increased the tumor area as compared with the rest of the treatments, whereas RU486 blocked P4 effects. All rats treated with P4 showed tumor infiltration, while 28.6% and 42.9% of the animals treated with RU486 and P4 + RU486, respectively, presented it. Our data suggest that P4 promotes growth and migration of human astrocytoma cells implanted in the motor cortex of the rat through the interaction with its intracellular receptor.