Cancer metastasis chemoprevention prevents circulating tumour cells from germination

The war against cancer traces back to the signature event half-a-century ago when the US National Cancer Act was signed into law. The cancer crusade costs trillions with disappointing returns, teasing the possibility of a new breakthrough. Cure for cancer post-metastases still seems tantalisingly out of reach. Once metastasized, cancer-related death is extremely difficult, if not impossible, to be reversed. Here we present cancer pre-metastasis chemoprevention strategy that can prevent circulating tumour cells (CTCs) from initiating metastases safely and effectively, and is disparate from the traditional cancer chemotherapy and cancer chemoprevention. Deep learning of the biology of CTCs and their disseminating organotropism, complexity of their adhesion to endothelial niche reveals that if the adhesion of CTCs to their metastasis niche (the first and the most important part in cancer metastatic cascade) can be pharmaceutically interrupted, the lethal metastatic cascade could be prevented from getting initiated. We analyse the key inflammatory and adhesive factors contributing to CTC adhesion/germination, provide pharmacological fundamentals for abortifacients to intervene CTC adhesion to the distant metastasis sites. The adhesion/inhibition ratio (AIR) is defined for selecting the best cancer metastasis chemopreventive candidates. The successful development of such new therapeutic modalities for cancer metastasis chemoprevention has great potential to revolutionise the current ineffective post-metastasis treatments.

Embedding similarities between embryos and circulating tumor cells: fundamentals of abortifacients used for cancer metastasis chemoprevention

Background

The global epidemiological studies reported lower cancer risk after long-term use of contraceptives. Our systematic studies demonstrated that abortifacients are effective in preventing cancer metastases induced by circulating tumor cells (CTCs). However, the molecular and cellular mechanisms by which abortifacients prevent CTC-based cancer metastases are almost unknown. The present studies were designed to interdisciplinarily explore similarities and differences between embryo implantation and cancer cell adhesion/invasion.

Methods

Biomarker expressions on the seeding embryo JEG-3 and cancer MCF-7 cells, as well as embedding uterine endometrial RL95-2 and vascular endothelial HUVECs cells were examined and compared before and after treatments with 17β-estradiol plus progesterone and abortifacients. Effects of oral metapristone and mifepristone on embryo implantation in normal female mice and adhesion/invasion of circulating tumor cells (CTCs) in BALB/C female mice were examined.

Results

Both embryo JEG-3 and cancer MCF-7 cells expressed high sLex, CD47, CAMs, while both endometrial RL95-2 and endothelial HUVECs exhibited high integrins and ICAM-1. Near physiological concentrations of 17β-estradiol plus progesterone promoted migration and invasion of JEG-3 and MCF-7 cells via upregulating integrins and MMPs. Whereas, mifepristone and metapristone significantly inhibited migration and invasion of JEG-3 and MCF-7 cells, and inhibited JEG-3 and MCF-7 adhesion to matrigel, RL95-2 cells and HUVECs, respectively. The inhibitions were realized by downregulating sLex, MMPs in JEG-3 and MCF-7 cells, and downregulating integrins in RL95-2 cells and HUVECs, respectively. Mifepristone and metapristone significantly inhibited both embryo implantation and cancer cell metastasis in mice.

Conclusions

The similarities between the two systems provide fundamentals for abortifacients to intervene CTC adhesion/invasion to the distant metastatic organs. The present studies offer the rationale to repurpose abortifacients for safe and effective cancer metastasis chemoprevention.

Identification of novel biomarkers of prostate cancer through integrated analysis

Background

The current methods adopted to screen for prostate cancer (PCa) can sometimes be misleading and inaccurate. Moreover, for advanced stages of PCa, the current effect of treatment is not satisfactory for some patients. Accordingly, we aimed to identify new biomarkers for the diagnosis and prognosis of PCa.

Methods

A series of bioinformatic tools were utilized to search for potential new biomarkers of PCa and analyze their functions, expression, clinical relevance, prognostic value, and underlying mechanisms.

Results

Although ASPN was overexpressed in PCa, EDN3, PENK, MEIS2, IGF1, and CXCL12 were downregulated. The univariate Cox regression analysis showed that abnormally high expression of ASPN and low expression of other genes predicted worse prognosis. Moreover, the multivariate Cox regression analysis showed that ASPN, PENK, and MEIS2 were independently associated with the overall survival (OS) of patients, whereas other markers were not. The outcomes of gene ontology and gene set enrichment analysis showed that the expression levels of these genes might be associated with cell proliferation and infiltration of immune cells in PCa.

Conclusions

We demonstrated that ASPN, EDN3, PENK, MEIS2, IGF1, and CXCL12 are possibly novel diagnostic indicators for PCa, whereas ASPN, PENK, and MEIS2 show appealing potential to predict the prognosis of this disease.

Current status of sorafenib nanoparticle delivery systems in the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of liver cancer and one of the leading causes of cancer-related death worldwide. Advanced HCC displays strong resistance to chemotherapy, and traditional chemotherapy drugs do not achieve satisfactory therapeutic efficacy. Sorafenib is an oral kinase inhibitor that inhibits tumor cell proliferation and angiogenesis and induces cancer cell apoptosis. It also improves the survival rates of patients with advanced liver cancer. However, due to its poor solubility, fast metabolism, and low bioavailability, clinical applications of sorafenib have been substantially restricted. In recent years, various studies have been conducted on the use of nanoparticles to improve drug targeting and therapeutic efficacy in HCC. Moreover, nanoparticles have been extensively explored to improve the therapeutic efficacy of sorafenib, and a variety of nanoparticles, such as polymer, lipid, silica, and metal nanoparticles, have been developed for treating liver cancer. All these new technologies have improved the targeted treatment of HCC by sorafenib and promoted nanomedicines as treatments for HCC. This review provides an overview of hot topics in tumor nanoscience and the latest status of treatments for HCC. It further introduces the current research status of nanoparticle drug delivery systems for treatment of HCC with sorafenib.

Regorafenib inhibits migration, invasion, and vasculogenic mimicry of hepatocellular carcinoma via targeting ID1-mediated EMT

Regorafenib is approved for patients with unresectable hepatocellular carcinoma (HCC) following sorafenib. However, the effect of regorafenib on HCC metastasis and its mechanism are poorly understood. Here, our data showed that regorafenib significantly restrained the migration, invasion and vasculogenic mimicry (VM) of HCC cells, and downregulated the expression of epithelial-to-mesenchymal transition (EMT)/VM-related molecules. Using RNA-seq and cellular thermal shift assays, we found that inhibitor of differentiation 1 (ID1) was a key target of regorafenib. In HCC tissues, the protein expression of ID1 was positively correlated with EMT and VM formation (CD34- /PAS+ ). Functionally, ID1 knockdown inhibited HCC cell migration, invasion, metastasis, and VM formation in vitro and in vivo, with upregulation of E-cadherin and downregulation of Snail and VE-cadherin. Moreover, Snail overexpression promoted the migration, invasion, and VM formation of ID1 knockdown cells. Snail knockdown reduced the migration, invasion, and VM formation of ID1 overexpression cells. Finally, regorafenib suppressed VM formation and decreased the expression of ID1, VE-cadherin and Snail in HCC PDX model. In conclusion, we manifested that regorafenib distinctly inhibited EMT in HCC cells via targeting ID1, leading to the suppression of cell migration, invasion and VM formation. These findings suggest that regorafenib may be developed as a suitable therapeutic agent for HCC metastasis.

Metapristone (RU486-derivative) inhibits endometrial cancer cell progress through regulating miR-492/Klf5/Nrf1 axis

Background

Endometrial cancer is an invasive gynecological cancer prevalent in the world. The pathogenesis of endometrial cancer is related to multiple levels of regulation, referring to oestrogen, tumor-suppressor gene (e.g. PTEN) or microRNAs (e.g. miR-23a and miR-29b). Metapristone is a hormone-related drug, which is widely used in clinical treatment of endometrial cancer. However, the underlying regulatory mechanism of metapristone on endometrial cancer is still unclear, especially the regulatory effect on microRNAs. The aim of this study is to investigate the specific molecular mechanism of metapristone regulating microRNAs in the treatment of endometrial cancer.

Methods

RL95-2 cells and Ishikawa cells were used as the endometrial cancer models. MiR-492 or si-miR-492 was transfected into RL95-2 cells and Ishikawa cells to explore the role of miR-492 in endometrial cancer. The cell cancer model and mice cancer model were used to confirm the function and mechanism of metapristone affected on endometrial cancer in vitro and in vivo. Mechanically, cell proliferation was monitored using MTT assay, cell colony formation assay and EdU assay. Luciferase reporter assay was used to identify the downstream target gene of miR-492. The protein expression and RNA expression were respectively measured by western blot and qRT-PCR for cell signaling pathway research, subsequently, were verified in the mice tumor model via immunohistochemistry.

Results

Metapristone as a kind of hormone-related drug significantly inhibited the endometrial cancer cell growth through regulating cell apoptosis-related gene expression. Mechanically, miR-492 and its target genes Klf5 and Nrf1 were highly expressed in the endometrial cancer cell lines, which promoted cell proliferation and inhibited cell apoptosis. Metapristone decreased the expression of miR-492 and its target genes Klf5 and Nrf1, leading to endometrial cancer cell growth inhibition in vitro and in vivo.

Conclusion

Metapristone inhibited the endometrial cancer cell growth through regulating the cell apoptosis-related signaling pathway and decreasing the expression of miR-492 and its downstream target genes (Klf5 and Nrf1), which provided the theoretical basis in clinical treatment of endometrial cancer.

The CXCL12-CXCR4 Signaling Axis Plays a Key Role in Cancer Metastasis and is a Potential Target for Developing Novel Therapeutics against Metastatic Cancer

Metastasis is the main cause of death in cancer patients; there is currently no effective treatment for cancer metastasis. This is primarily due to our insufficient understanding of the metastatic mechanisms in cancer. An increasing number of studies have shown that the C-X-C motif chemokine Ligand 12 (CXCL12) is overexpressed in various tissues and organs. It is a key niche factor that nurtures the pre-metastatic niches (tumorigenic soil) and recruits tumor cells (oncogenic "seeds") to these niches, thereby fostering cancer cell aggression and metastatic capabilities. However, the C-X-C motif chemokine Receptor 4 (CXCR4) is aberrantly overexpressed in various cancer stem/progenitor cells and functions as a CXCL12 receptor. CXCL12 activates CXCR4 as well as multiple downstream multiple tumorigenic signaling pathways, promoting the expression of various oncogenes. Activation of the CXCL12-CXCR4 signaling axis promotes Epithelial-Mesenchymal Transition (EMT) and mobilization of cancer stem/progenitor cells to pre-metastatic niches. It also nurtures cancer cells with high motility, invasion, and dissemination phenotypes, thereby escalating multiple proximal or distal cancer metastasis; this results in poor patient prognosis. Based on this evidence, recent studies have explored either CXCL12- or CXCR4-targeted anti-cancer therapeutics and have achieved promising results in the preclinical trials. Further exploration of this new strategy and its potent therapeutics effect against metastatic cancer through the targeting of the CXCL12- CXCR4 signaling axis may lead to a novel therapy that can clean up the tumor microenvironment ("soil") and kill the cancer cells, particularly the cancer stem/progenitor cells ("seeds"), in cancer patients. Ultimately, this approach has the potential to effectively treat metastatic cancer.

CXCL12/CXCR4 Axis-Targeted Dual-Functional Nano-Drug Delivery System Against Ovarian Cancer

Introduction

Traditional chemotherapy for ovarian cancer is limited due to drug resistance and systemic side effects. Although various targeted drug delivery strategies have been designed to enhance drug accumulation at the tumor site, simply improvement of targeting capability has not consistently led to satisfactory outcomes. Herein, AMD3100 was selected as the targeting ligand because of its high affinity to chemokine receptor 4 (CXCR4), which was highly expressed on ovarian cancer cells. Moreover, the AMD3100 has been proved having blockage capability of stromal cell-derived factor 1 (SDF-1 or CXCL12)/CXCR4 axis and to be a sensitizer of chemotherapeutic therapy. We designed a dual-functional targeting delivery system by modifying paclitaxel (PTX)-loaded PEGylation bovine serum albumin (BSA) nanoparticles (NPs) with AMD3100 (AMD-NP-PTX), which can not only achieve specific tumor-targeting efficiency but also enhance the therapeutic outcomes.

Methods

AMD3100 was chemically modified to Mal-PEG-NHS followed by reacting with BSA, then AMD-NP-PTX was synthesized and characterized. The targeting efficiency of AMD-NP was evaluated both in vitro and in vivo. The anticancer effect of AMD-NP-PTX was determined on Caov3 cells and ovarian cancer-bearing nude mice. Finally, the potential therapeutic mechanism was studied.

Results

AMD-NP-PTX was synthesized successfully and well characterized. Cellular uptake assay and in vivo imaging experiments demonstrated that NPs could be internalized by Caov3 cells more efficiently after modification of AMD3100. Furthermore, the AMD-NP-PTX exhibited significantly enhanced inhibition effect on tumor growth and metastasis compared with PTX, NP-PTX and free AMD3100 plus NP-PTX both in vitro and in vivo, and demonstrated improved safety profile. We also confirmed that AMD-NP-PTX worked through targeting CXCL12/CXCR4 axis, thereby disturbing its downstream signaling pathways including epithelial–mesenchymal transition (EMT) processes and nuclear factor κB (NF-κB) pathway.

Conclusion

The AMD-NP-PTX we designed would open a new avenue for dual-functional NPs in ovarian cancer therapy.

CXCR4 antagonist AMD3100 (plerixafor): From an impurity to a therapeutic agent

AMD3100 (plerixafor), a CXCR4 antagonist, has opened a variety of avenues for potential therapeutic approaches in different refractory diseases. The CXCL12/CXCR4 axis and its signaling pathways are involved in diverse disorders including HIV-1 infection, tumor development, non-Hodgkin lymphoma, multiple myeloma, WHIM Syndrome, and so on. The mechanisms of action of AMD3100 may relate to mobilizing hematopoietic stem cells, blocking infection of X4 HIV-1, increasing circulating neutrophils, lymphocytes and monocytes, reducing myeloid-derived suppressor cells, and enhancing cytotoxic T-cell infiltration in tumors. Here, we first revisit the pharmacological discovery of AMD3100. We then review monotherapy of AMD3100 and combination use of AMD3100 with other agents in various diseases. Among those, we highlight the perspective of AMD3100 as an immunomodulator to regulate immune responses particularly in the tumor microenvironment and synergize with other therapeutics. All the pre-clinical studies support the clinical testing of the monotherapy and combination therapies with AMD3100 and further development for use in humans.

WDR74 modulates melanoma tumorigenesis and metastasis through the RPL5-MDM2-p53 pathway

The key molecules and underlying mechanisms of melanoma metastasis remain poorly understood. Using isobaric tag for relative and absolute quantitation (iTRAQ) proteomic screening, probing of patients' samples, functional verification, and mechanistic validation, we identified the important role of the WD repeat-containing protein 74 (WDR74) in melanoma progression and metastasis. Through gain- and loss-of-function approaches, WDR74 was found to promote cell proliferation, apoptosis resistance, and aggressive behavior in vitro. Moreover, WDR74 contributed to melanoma growth and metastasis in vivo. Mechanistically, WDR74 modulates RPL5 protein levels and consequently regulates MDM2 and insulates the ubiquitination degradation of p53 by MDM2. Our study is the first to reveal the oncogenic role of WDR74 in melanoma progression and the regulatory effect of WDR74 on the RPL5-MDM2-p53 pathway. Collectively, WDR74 can serve as a candidate target for the prevention and treatment of melanoma in the clinic.

COX-2 Signaling in the Tumor Microenvironment

Tumorigenesis is a multistep, complicated process, and many studies have been completed over the last few decades to elucidate this process. Increasingly, many studies have shifted focus toward the critical role of the tumor microenvironment (TME), which consists of cellular players, cell-cell communications, and extracellular matrix (ECM). In the TME, cyclooxygenase-2 (COX-2) has been found to be a key molecule mediating the microenvironment changes. COX-2 is an inducible form of the enzyme that converts arachidonic acid into the signal transduction molecules (thromboxanes and prostaglandins). COX-2 is frequently expressed in many types of cancers and has been closely linked to its occurrence, progression, and prognosis. For example, COX-2 has been shown to (1) regulate tumor cell growth, (2) promote tissue invasion and metastasis, (3) inhibit apoptosis, (4) suppress antitumor immunity, and (5) promote sustainable angiogenesis. In this chapter, we summarize recent advances of studies that have evaluated COX-2 signaling in TME.

Reversing the Tumor Target: Establishment of a Tumor Trap

Despite the tremendous progress made in the field of cancer therapy in recent years, certain solid tumors still cannot be successfully treated. Alongside classical treatments in the form of chemotherapy and/or radiotherapy, targeted treatments such as immunotherapy that cause fewer side effects emerge as new options in the clinics. However, these alternative treatments may not be useful for treating all types of cancers, especially for killing infiltrative and circulating tumor cells (CTCs). Recent advances pursue the trapping of these cancer cells within a confined area to facilitate their removal for therapeutic and diagnostic purposes. A good understanding of the mechanisms behind tumor cell migration may drive the design of traps that mimic natural tumor niches and guide the movement of the cancer cells. To bring this trapping idea into reality, strong efforts are being made to create structured materials that imitate myelinated fibers, blood vessels, or pre-metastatic niches and incorporate chemical cues such as chemoattractants or adhesive proteins. In this review, the different strategies used (or could be used) to trap tumor cells are described, and relevant examples of their performance are analyzed.

Co-delivery of sorafenib and metapristone encapsulated by CXCR4-targeted PLGA-PEG nanoparticles overcomes hepatocellular carcinoma resistance to sorafenib

Background

Sorafenib is approved as a standard therapy for advanced hepatocellular carcinoma (HCC), but its clinical application is limited due to moderate therapeutic efficacy and high incidence of acquired resistance resulted from elevated levels of SDF-1/CXCR4 axis induced by prolonged sorafenib treatment. We previously demonstrated metapristone (RU486 metabolite) as a cancer metastatic chemopreventive agent targeting SDF-1/CXCR4 axis. Therefore, we hypothesized that combining sorafenib with metapristone could synergistically suppress cell proliferation, enhance anti-cancer activity and repress potential drug resistance.

Methods

Changes in cellular CXCR4 expression by metapristone were analyzed by RT-PCR and western blotting. Effect of combining sorafenib with metapristone on cell viability was examined by MTT assay; combination index value was calculated to evaluate the synergistic effect of combined therapy. To overcome poor pharmacokinetics and reduce off-target toxicity, CXCR4-targeted nanoparticles (NPs) were developed to co-deliver sorafenib and metapristone into CXCR4-expressing HCC in vitro and in vivo; cell proliferation, colony formation and apoptosis assays were conducted; nude mice bearing HCC xenograft were used to examine effects of this therapeutic approach on HCC progression.

Results

Here we showed metapristone significantly reduced CXCR4 expression in HCC. Combinatory chemotherapy of sorafenib with metapristone synergistically suppressed HCC proliferation and resistance. CXCR4-targeted PEGylated poly (lactic-co-glycolic acid) NPs conjugated with LFC131 (a peptide inhibitor of CXCR4), could deliver more sorafenib and metapristone into HCC via specific recognition and binding with transmembrane CXCR4, and resulted in the enhanced cytotoxicity, colony inhibition and apoptosis by regulating more Akt/ERK/p38 MAPK/caspase signaling pathways. Co-delivery of sorafenib with metapristone by the LFC131-conjugated NPs showed prolonged circulation and target accumulation at tumor sites, and thus suppressed tumor growth in a tumor xenograft model.

Conclusions

In conclusion, co-delivery of sorafenib and metapristone via the CXCR4-targeted NPs displays a synergistic therapy against HCC. Our results suggest combinational treatment of chemotherapeutics offer an effective strategy for enhancing the therapeutic efficacy on carcinoma, and highlight the potential application of ligand-modified tumor-targeting nanocarriers in delivering drugs as a promising cancer therapeutic approach.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1216-x) contains supplementary material, which is available to authorized users.

Advanced assessment of migration and invasion of cancer cells in response to mifepristone therapy using double fluorescence cytochemical labeling

Background

Previous work in our laboratory demonstrated that antiprogestin mifepristone impairs the growth and adhesion of highly metastatic cancer cells, and causes changes in their cellular morphology. In this study, we further assess the anti-metastatic properties of mifepristone, by studying whether cytostatic doses of the drug can inhibit the migration and invasion of various cancer cell lines using a double fluorescence cytochemical labeling approach.

Methods

Cell lines representing cancers of the ovary (SKOV-3), breast (MDA-MB-231), glia (U87MG), or prostate (LNCaP) were treated with cytostatic concentrations of mifepristone. Wound healing and Boyden chamber assays were utilized to study cellular migration. To study cellular invasion, the Boyden chamber assay was prepared by adding a layer of extracellular matrix over the polycarbonate membrane. We enhanced the assays with the addition of double fluorescence cytochemical staining for fibrillar actin (F-actin) and DNA to observe the patterns of cytoskeletal distribution and nuclear positioning while cells migrate and invade.

Results

When exposed to cytostatic concentrations of mifepristone, all cancer cells lines demonstrated a decrease in both migration and invasion capacities measured using standard approaches. Double fluorescence cytochemical labeling validated that mifepristone-treated cancer cells exhibit reduced migration and invasion, and allowed to unveil a distinct migration pattern among the different cell lines, different arrays of nuclear localization during migration, and apparent redistribution of F-actin to the nucleus.

Conclusion

This study reports that antiprogestin mifepristone inhibits migration and invasion of highly metastatic cancer cell lines, and that double fluorescence cytochemical labeling increases the value of well-known approaches to study cell movement.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5587-3) contains supplementary material, which is available to authorized users.

Cyclooxygenase-2 in cancer: A review

Cyclooxygenase-2 (COX-2) is frequently expressed in many types of cancers exerting a pleiotropic and multifaceted role in genesis or promotion of carcinogenesis and cancer cell resistance to chemo- and radiotherapy. COX-2 is released by cancer-associated fibroblasts (CAFs), macrophage type 2 (M2) cells, and cancer cells to the tumor microenvironment (TME). COX-2 induces cancer stem cell (CSC)-like activity, and promotes apoptotic resistance, proliferation, angiogenesis, inflammation, invasion, and metastasis of cancer cells. COX-2 mediated hypoxia within the TME along with its positive interactions with YAP1 and antiapoptotic mediators are all in favor of cancer cell resistance to chemotherapeutic drugs. COX-2 exerts most of the functions through its metabolite prostaglandin E2. In some and limited situations, COX-2 may act as an antitumor enzyme. Multiple signals are contributed to the functions of COX-2 on cancer cells or its regulation. Members of mitogen-activated protein kinase (MAPK) family, epidermal growth factor receptor (EGFR), and nuclear factor-κβ are main upstream modulators for COX-2 in cancer cells. COX-2 also has interactions with a number of hormones within the body. Inhibition of COX-2 provides a high possibility to exert therapeutic outcomes in cancer. Administration of COX-2 inhibitors in a preoperative setting could reduce the risk of metastasis in cancer patients. COX-2 inhibition also sensitizes cancer cells to treatments like radio- and chemotherapy. Chemotherapeutic agents adversely induce COX-2 activity. Therefore, choosing an appropriate chemotherapy drugs along with adjustment of the type and does for COX-2 inhibitors based on the type of cancer would be an effective adjuvant strategy for targeting cancer.

CXCR7 is not obligatory for CXCL12-CXCR4-induced epithelial-mesenchymal transition in human ovarian cancer

Although the CXCL12-CXCR4/CXCR7 chemokine axis is demonstrated to play an integral role in tumor progression, the controversy exists and the role of CXCL12-CXCR4/CXCR7 signaling axis in epithelial-mesenchymal transition (EMT) of human ovarian cancer has not been explored. Here, we showed that in ovarian cancer CXCL12 induced EMT phenotypes including the spindle-like cell morphology, podia and stress fiber formation, a decrease in E-cadherin expression, and increases in mesenchymal N-cadherin and vimentin expressions. These effects of CXCL12 could be antagonized by the CXCR4 antagonist AMD3100, but not by the anti-CXCR7 antibody. The expressions of the EMT markers were significantly down-regulated by the CXCR4 siRNA, and up-regulated by the pcDNA3.1/CXCR4 plasmid, whereas not affected by the CXCR7 siRNA. Furthermore, intraperitoneal administration of AMD3100 inhibited tumor dissemination and growth in the nude mice inoculated with ovarian IGROV-1 cells with a concomitant reduction in EMT marker expressions. Collectively, these data suggest that CXCR4, rather than CXCR7, plays a key role in CXCL12-activated EMT phenotypes, and targeting the CXCL12-CXCR4 chemokine axis represents a potential therapeutic strategy to prevent ovarian cancer progression.

Contribution of regulatory T cells to cancer: A review

Regulatory T cells (Tregs) represent a low number of T-cell population under normal conditions, and they play key roles for maintaining immune system in homeostasis. The number of these cells is extensively increased in nearly all cancers, which is for dampening responses from immune system against cancer cells, metastasis, tumor recurrence, and treatment resistance. The interesting point is that apoptotic Tregs are stronger than their live counterparts for suppressing responses from immune system. Tregs within the tumor microenvironment have extensive positive cross-talks with other immunosuppressive cells including cancer-associated fibroblasts, cancer cells, macrophage type 2 cells, and myeloid-derived suppressor cells, and they have negative interactions with immunostimulatory cells including cytotoxic T lymphocytes (CTL) and natural killer cells. A wide variety of markers are expressed in Tregs, among them forkhead box P3 (FOXP3) is the most specific marker and the master regulator of these cells. Multiple signals are activated by Tregs including transforming growth factor-β, signal transducer and activator of transcription, and mTORC1. Treg reprogramming from an immunosuppressive to immunostimulatory proinflammatory phenotype is critical for increasing the efficacy of immunotherapy. This would be applicable through selective suppression of tumor-bearing receptors in Tregs, including FOXP3, programmed death-1, T-cell immunoglobulin mucin-3, and CTL-associated antigen-4, among others. Intratumoral Tregs can also be targeted by increasing the ratio for CTL/Treg.

Role of CXCL12-CXCR4 axis in ovarian cancer metastasis and CXCL12-CXCR4 blockade with AMD3100 suppresses tumor cell migration and invasion in vitro

Ovarian cancer (OC) is a lethal gynecologic tumor, which brings its mortality to the head. CXCL12 and its receptor chemokine receptor 4 ( CXCR4) have been found to be highly expressed in OC and contribute to the disease progression by affecting tumor cell proliferation and invasion. Here, in this study, we aim to explore whether the blockade of CXCL12-CXCR4 axis with AMD3100 (a selective CXCR4 antagonist) has effects on the progression of OC. On the basis of the gene expression omnibus database of OC gene expression chips, the OC differentially expressed genes were screened by microarray analysis. OC (nonmetastatic and metastatic) and normal ovarian tissues were collected to determine the expressions of CXCL12 and CXCR4. A series of AMD3100, shRNA against CXCR4, and pCNS-CXCR4 were introduced to treat CAOV3 cells with the highest CXCR4 was assessed. Cell viability, apoptosis, migration, and invasion were all evaluated. The microarray analysis screened out the differential expression of CXCL12-CXCR4 in OC. CXCL12 and CXCR4 expressions were increased in OC tissues, particularly in the metastatic OC tissues. Downregulation of CXCR4 by AMD3100 or shRNA was observed to have a critical role in inhibiting cell proliferation, migration, and invasion of the CAOV3 OC cell line while promoting cell apoptosis. Overexpressed CXCR4 brought significantly promoting effects on the proliferation and invasiveness of OC cells. These results reinforce that the blockade of CXCL12-CXCR4 axis with AMD3100 inhibits the growth of OC cells. The antitumor role of the inhibition of CXCL12-CXCR4 axis offers a preclinical validation of CXCL12-CXCR4 axis as a therapeutic target in OC.

Metapristone (RU486 metabolite) suppresses NSCLC by targeting EGFR-mediated PI3K/AKT pathway

Therapies targeting epidermal growth factor receptor (EGFR) can effectively treat with non-small cell lung cancer (NSCLC), but NSCLC's drug resistance makes it intractable. Herein, we showed that RU486 metabolite metapristone inhibited the proliferation of various NSCLC cell lines with either wild (A549, H1299, H520) or mutated EGFR (H1975, HCC827). The suppression was resulted from inhibition by metapristone of EGFR signaling pathways through down-regulating the EGFR, PTEN, as well as AKT and ERK proteins. In addition, metapristone inhibited anti-apoptotic marker Bcl-2, and activated pro-apoptotic key signaling proteins caspase-3, and poly (ADP-ribose) polymerase. Metapristone induced A549 and H1975 cell cycle via arrest at the G0-G1 stage. What's more, metapristone inhibited the growth of NSCLC xenografts in BALB/c nude mice through decreasing the expression of tumor growth biomarkers PCNA and EGFR. Taken together, the present study demonstrated that metapristone suppressed NSCLC proliferation by promoting apoptosis via decrease the cellular EGFR-mediated PI3K/AKT pathways. The results suggest metapristone a new treatment for EGFR-overexpressed NSCLC.

Mifepristone inhibits ovarian cancer metastasis by intervening in SDF-1/CXCR4 chemokine axis

SDF-1/CXCR4 signaling axis determines the proliferative potential and site-specific cancer metastasis. Recent studies suggest involvement of the axis and steroidal hormone in ovarian cancer metastasis. Here we hypothesize that mifepristone (RU486), a well-known progesterone-based abortifacient, might interfere this axis and inhibit ovarian cancer metastasis. Mifepristone at concentrations < IC50 inhibited expression of CXCR4 on cell surface of ovarian cancer SKOV-3 and IGROV-1, and reduced expression of the intracellular CXCR4 protein and its related mRNA activated by SDF-1. SDF-1 significantly stimulated proliferation of SKOV-3 and IGROV-1 cells with concomitant increases in intracellular phosphorylation of Akt and ERK. SDF-1 activated cell chemotatic migration and actin polymerization, and up-regulated expression of MMP-2, MMP-9, COX-2, VEGF without influencing the adhesion molecules ICAM-1 and integrins β1, α1, α3, α5, and α6. The above-mentioned effects of SDF-1 could be antagonized by mifepristone concentration-dependently, and CXCR4 antagonist AMD3100. Mifepristone suppressed the SDF-1-induced migration, invasion and adhesion of the cancer cells to extracellular matrixes. Three-day pretreatment of nude mice with mifepristone (5 and 20 mg/kg/day) followed by a single intraperitoneal IGROV-1 inoculation, along with repeated SDF-1 and mifepristone administrations in turn every other day for 36 days significantly reduced ascitic fluid, metastatic foci, tumor weight and immunoreactivity of CXCR4 in comparison with the SDF-1-treated control. Our results suggest that mifepristone inhibit SDF-1/CXCR4 signaling axis, may have preventive and therapeutic effects on ovarian cancer metastasis.