Sphingosine kinase 1 is a reliable prognostic factor and a novel therapeutic target for uterine cervical cancer

SLC5A3 is important for cervical cancer cell growth

Novel molecular targets for cervical cancer must be identified. This study examined the role of SLC5A3, a myo-inositol transporter, in the pathogenesis of cervical cancer. Through boinformatics analysis, we showed that the SLC5A3 mRNA levels were upregulated in cervical cancer tissues. The upregulated SLC5A3 mRNA levels were negatively correlated with survival and progression-free interval. Genes co-expressed with SLC5A3 were enriched in multiple signaling cascades involved in cancer progression. In primary/established cervical cancer cells, SLC5A3 shRNA/knockout (KO) exerted growth-inhibitory effects and promoted cell death/apoptosis. Furthermore, SLC5A3 knockdown or KO downregulated myo-inositol levels, induced oxidative injury, and decreased Akt-mTOR activation in cervical cancer cells. In contrast, supplementation of myo-inositol or n-acetyl-L-cysteine or transduction of a constitutively active Akt1 construct mitigated SLC5A3 KO-induced cytotoxicity in cervical cancer cells. Lentiviral SLC5A3 overexpression construct transduction upregulated the cellular myo-inositol level and promoted Akt-mTOR activation, enhancing cervical cancer cell proliferation and migration. The binding of TonEBP to the SLC5A3 promoter was upregulated in cervical cancer. In vivo studies showed that intratumoral injection of SLC5A3 shRNA-expressing virus arrested cervical cancer xenograft growth in mice. SLC5A3 KO also inhibited pCCa-1 cervical cancer xenograft growth. The SLC5A3-depleted xenograft tissues exhibited myo-inositol downregulation, Akt-mTOR inactivation, and oxidative injury. Transduction of sh-TonEBP AAV construct downregulated SLC5A3 expression and inhibited pCCa-1 cervical cancer xenograft growth. Together, overexpressed SLC5A3 promotes growth of cervical cancer cells, representing as a novel therapeutic oncotarget for the devastating disease.

The Expression and Clinical Significance of Sphingosine Kinase 1 and Vascular Endothelial Growth Factor in Endometrial Carcinoma

The aim of the study is to investigate the expression of sphingosine kinase 1 (SPHK1) and vascular endothelial growth factor (VEGF) in patients with endometrial carcinoma and its clinical significance. The tissues of 86 cases of patients with endometrial carcinoma and 54 cases of patients with endometrial atypical hyperplasia were collected. The expression of SPHK1 and VEGF in the tissue was detected by immunohistochemistry. The expression of SPHK1 in patients with endometrial carcinoma was compared with the clinicopathological data. Results. 69 cases (82.1%) of endometrial carcinoma were positive for SPHK1, which was higher than 2 cases (3.7%) of endometrial atypical hyperplasia (P < 0.05). The VEGF expression in 54 patients (62.8%) with endometrial carcinoma was higher than that in 12 patients with endometrial atypical hyperplasia (22.2%) (P < 0.05). There was a positive correlation between SPHK1 and VEGF expressions in endometrial carcinoma (c = 0.595). The expression of SPHK1 in endometrial cancer patients was different in different pathological types, FIGO stages, lymph node metastasis, ER, and PR positive or not, and the difference between the two groups was significant (P < 0.05). There was no difference in age, degree of differentiation, and depth of myometrial infiltration (P < 0.05). The expression of SPHK1 in patients with endometrial carcinoma is increased, which is helpful for early detection of patients with endometrial carcinoma, and may play a synergistic role with VEGF in the pathogenesis and development of endometrial carcinoma.

Validation of a Patient-Derived Xenograft Model for Cervical Cancer Based on Genomic and Phenotypic Characterization

Simple Summary

The rate of total tumor engraftment of patient-derived xenografts is 50% in cervical cancer. These cancers retain their histopathological characteristics. The gene mutations and expression patterns associated with carcinogenesis and infiltration and the expression levels of genes in extracellular vesicles released from the tumors are similar between patient-derived xenograft models and primary tumors. Patient-derived xenograft models of cervical cancer could be potentially useful tools for translational research.

Abstract

Patient-derived xenograft (PDX) models are useful tools for preclinical drug evaluation, biomarker identification, and personalized medicine strategies, and can be developed by the heterotopic or orthotopic grafting of surgically resected tumors into immunodeficient mice. We report the PDX models of cervical cancer and demonstrate the similarities among original and different generations of PDX tumors. Fresh tumor tissues collected from 22 patients with primary cervical cancer were engrafted subcutaneously into NOD.CB17-PrkdcSCID/J mice. Histological and immunohistochemical analyses were performed to compare primary and different generations of PDX tumors. DNA and RNA sequencing were performed to verify the similarity between the genetic profiles of primary and PDX tumors. Total RNA in extracellular vesicles (EVs) released from primary and PDX tumors was also quantified to evaluate gene expression. The total tumor engraftment rate was 50%. Histologically, no major differences were observed between the original and PDX tumors. Most of the gene mutations and expression patterns related to carcinogenesis and infiltration were similar between the primary tumor and xenograft. Most genes associated with carcinogenesis and infiltration showed similar expression levels in the primary tumor and xenograft EVs. Therefore, compared with primary tumors, PDX models could be potentially more useful for translational research.

Increased Sphingosine Kinase 1 Expression Is Associated with Poor Prognosis in Human Solid Tumors: A Meta-Analysis

Methods

PubMed, Web of Science, Embase, CNKI, and Wanfang databases were thoroughly searched for eligible studies, in which the relationship between SPHK1 expression and cancer prognosis was evaluated. Hazard ratios (HRs) and 95% confidence intervals (CIs) were pooled to estimate the impact of SPHK1 expression on cancer patients' survival. Odds ratios (ORs) and 95% CIs were combined to assess the association between SPHK1 expression and clinicopathological characteristics of cancer patients. The certainty of evidence was evaluated by Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) criteria.

Results

Thirty studies comprising 32 cohorts with 5965 patients were included in this meta-analysis. The outcomes indicated that elevated SPHK1 expression was associated with worse overall survival (OS) (HR = 1.71, 95% CI: 1.45-2.01, P < 0.001) and disease-free survival (DFS) (HR = 1.34, 95% CI: 1.13-1.59, P = 0.001). What is more, SPHK1 overexpression was significantly correlated with certain phenotypes of tumor aggressiveness, such as clinical stage (OR = 2.07, 95% CI: 1.39-3.09, P < 0.001), tumor invasion (OR = 2.16, 95% CI: 1.47-3.18, P < 0.001), lymph node metastasis (OR = 2.04, 95% CI: 1.71-2.44, P < 0.001), and distant metastasis (OR = 3.16, 95% CI: 2.44-4.09, P < 0.001). The quality of the evidence for both OS and DFS was low.

Conclusions

Increased SPHK1 expression is related to poor prognosis in human cancers and may serve as a promising prognostic marker and therapeutic target for malignant patients. However, conclusions need to be treated with caution because of lack of high quality of evidence.

Targeting Sphingolipids for Cancer Therapy

Sphingolipids are an extensive class of lipids with different functions in the cell, ranging from proliferation to cell death. Sphingolipids are modified in multiple cancers and are responsible for tumor proliferation, progression, and metastasis. Several inhibitors or activators of sphingolipid signaling, such as fenretinide, safingol, ABC294640, ceramide nanoliposomes (CNLs), SKI-II, α-galactosylceramide, fingolimod, and sonepcizumab, have been described. The objective of this review was to analyze the results from preclinical and clinical trials of these drugs for the treatment of cancer. Sphingolipid-targeting drugs have been tested alone or in combination with chemotherapy, exhibiting antitumor activity alone and in synergism with chemotherapy in vitro and in vivo. As a consequence of treatments, the most frequent mechanism of cell death is apoptosis, followed by autophagy. Aslthough all these drugs have produced good results in preclinical studies of multiple cancers, the outcomes of clinical trials have not been similar. The most effective drugs are fenretinide and α-galactosylceramide (α-GalCer). In contrast, minor adverse effects restricted to a few subjects and hepatic toxicity have been observed in clinical trials of ABC294640 and safingol, respectively. In the case of CNLs, SKI-II, fingolimod and sonepcizumab there are some limitations and absence of enough clinical studies to demonstrate a benefit. The effectiveness or lack of a major therapeutic effect of sphingolipid modulation by some drugs as a cancer therapy and other aspects related to their mechanism of action are discussed in this review.

Patient-Derived Xenograft Models in Cervical Cancer: A Systematic Review

BACKGROUND

Patient-derived xenograft (PDX) models have been a focus of attention because they closely resemble the tumor features of patients and retain the molecular and histological features of diseases. They are promising tools for translational research. In the current systematic review, we identify publications on PDX models of cervical cancer (CC-PDX) with descriptions of main methodological characteristics and outcomes to identify the most suitable method for CC-PDX.

METHODS

We searched on PubMed to identify articles reporting CC-PDX. Briefly, the main inclusion criterion for papers was description of PDX created with fragments obtained from human cervical cancer specimens, and the exclusion criterion was the creation of xenograft with established cell lines.

RESULTS

After the search process, 10 studies were found and included in the systematic review. Among 98 donor patients, 61 CC-PDX were established, and the overall success rate was 62.2%. The success rate in each article ranged from 0% to 75% and was higher when using severe immunodeficient mice such as severe combined immunodeficient (SCID), nonobese diabetic (NOD) SCID, and NOD SCID gamma (NSG) mice than nude mice. Subrenal capsule implantation led to a higher engraftment rate than orthotopic and subcutaneous implantation. Fragments with a size of 1-3 mm3 were suitable for CC-PDX. No relationship was found between the engraftment rate and characteristics of the tumor and donor patient, including histology, staging, and metastasis. The latency period varied from 10 days to 12 months. Most studies showed a strong similarity in pathological and immunohistochemical features between the original tumor and the PDX model.

CONCLUSION

Severe immunodeficient mice and subrenal capsule implantation led to a higher engraftment rate; however, orthotopic and subcutaneous implantation were alternatives. When using nude mice, subrenal implantation may be better. Fragments with a size of 1-3 mm3 were suitable for CC-PDX. Few reports have been published about CC-PDX; the results were not confirmed because of the small sample size.

The Role of Ceramide Metabolism and Signaling in the Regulation of Mitophagy and Cancer Therapy

Simple Summary

Sphingolipids are membrane-associated lipids that are involved in signal transduction pathways regulating cell death, growth, and migration. In cancer cells, sphingolipids regulate pathways relevant to cancer therapy, such as invasion, metastasis, apoptosis, and lethal mitophagy. Notable sphingolipids include ceramide, a sphingolipid that induces death and lethal mitophagy, and sphingosine-1 phosphate, a sphingolipid that induces survival and chemotherapeutic resistance. These sphingolipids participate in regulating the process of mitophagy, where cells encapsulate damaged mitochondria in double-membrane vesicles (called autophagosomes) for degradation. Lethal mitophagy is an anti-tumorigenic mechanism mediated by ceramide, where cells degrade many mitochondria until the cancer cell dies in an apoptosis-independent manner.

Abstract

Sphingolipids are bioactive lipids responsible for regulating diverse cellular functions such as proliferation, migration, senescence, and death. These lipids are characterized by a long-chain sphingosine backbone amide-linked to a fatty acyl chain with variable length. The length of the fatty acyl chain is determined by specific ceramide synthases, and this fatty acyl length also determines the sphingolipid’s specialized functions within the cell. One function in particular, the regulation of the selective autophagy of mitochondria, or mitophagy, is closely regulated by ceramide, a key regulatory sphingolipid. Mitophagy alterations have important implications for cancer cell proliferation, response to chemotherapeutics, and mitophagy-mediated cell death. This review will focus on the alterations of ceramide synthases in cancer and sphingolipid regulation of lethal mitophagy, concerning cancer therapy.

L-ascorbyl 6-palmitate as lead compound targeting SphK1: an in silico and in vitro investigation

Sphingosine kinases (SphKs) are a class of lipid kinases, that have received extensive attention as important rate-limiting enzyme in tumor. Inhibition of the activity of SphK1 can lead to an anticancer effect. Herein, we describe the discovery process and biological characteristics of a new SphK1 inhibitor, ascorbyl palmitate, discovered through computer-aided drug design. Biochemical experiments show that ascorbyl palmitate has a strong inhibitory effect on SphK1, with an IC50 value of 6.4 μM. The MTT experiment showed that ascorbyl palmitate had anti-cancer effects toward the U87, A549, 22RV1, and A375 cell lines. Among them, ascorbyl palmitate has prominent inhibitory activity against the 22RV1 cell line, with an IC50 value of 41.57 μM. To explore the structure–activity relationship, four ascorbyl palmitate derivatives were synthesized and tested for kinase activity. The outstanding effect of ascorbyl palmitate toward SphK1 and its known non-toxicity suggest that ascorbyl palmitate may be a lead compound for the development of effective SphK1 anti-cancer inhibitors.

Exploring Metabolic Adaptations to the Acidic Microenvironment of Osteosarcoma Cells Unveils Sphingosine 1-Phosphate as a Valuable Therapeutic Target

Simple Summary

By studying the role of tumor acidosis in osteosarcoma, we have identified a novel lipid signaling pathway that is selectively activated in acid-induced highly metastatic cell subpopulation. Furthermore, when combined to low-serine/glycine diet, the targeting of this acid-induced lipid pathway by the FDA-approved drug FTY720 significantly impaired tumor growth. This new knowledge will provide a giant leap in the understanding of the molecular mechanisms responsible for sarcoma relapses and metastasis. Finally, we paved the way to the recognition of a novel biomarker, as our data provided evidence of significantly high circulating levels in the serum of osteosarcoma patients of S1P, a lipid member of the identified acid-driven metabolic pathway.

Abstract

Acidity is a key player in cancer progression, modelling a microenvironment that prevents immune surveillance and enhances invasiveness, survival, and drug resistance. Here, we demonstrated in spheroids from osteosarcoma cell lines that the exposure to acidosis remarkably caused intracellular lipid droplets accumulation. Lipid accumulation was also detected in sarcoma tissues in close proximity to tumor area that express the acid-related biomarker LAMP2. Acid-induced lipid droplets-accumulation was not functional to a higher energetic request, but rather to cell survival. As a mechanism, we found increased levels of sphingomyelin and secretion of the sphingosine 1-phosphate, and the activation of the associated sphingolipid pathway and the non-canonical NF-ĸB pathway, respectively. Moreover, decreasing sphingosine 1-phosphate levels (S1P) by FTY720 (Fingolimod) impaired acid-induced tumor survival and migration. As a confirmation of the role of S1P in osteosarcoma, we found S1P high circulating levels (30.8 ± 2.5 nmol/mL, n = 17) in the serum of patients. Finally, when we treated osteosarcoma xenografts with FTY720 combined with low-serine/glycine diet, both lipid accumulation (as measured by magnetic resonance imaging) and tumor growth were greatly inhibited. For the first time, this study profiles the lipidomic rearrangement of sarcomas under acidic conditions, suggesting the use of anti-S1P strategies in combination with standard chemotherapy.

The Tumorigenic Effect of Sphingosine Kinase 1 and Its Potential Therapeutic Target

Sphingosine kinase 1 (SPHK1) regulates cell proliferation and survival by converting sphingosine to the signaling mediator sphingosine 1-phosphate (S1P). SPHK1 is widely overexpressed in most cancers, promoting tumor progression and is associated with clinical prognosis. Numerous studies have explored SPHK1 as a promising target for cancer therapy. However, due to insufficient knowledge of SPHK1 oncogenic mechanisms, its inhibitors’ therapeutic potential in preventing and treating cancer still needs further investigation. In this review, we summarized the metabolic balance regulated by the SPHK1/S1P signaling pathway and highlighted the oncogenic mechanisms of SPHK1 via the upregulation of autophagy, proliferation, and survival, migration, angiogenesis and inflammation, and inhibition of apoptosis. Drug candidates targeting SPHK1 were also discussed at the end. This review provides new insights into the oncogenic effect of SPHK1 and sheds light on the future direction for targeting SPHK1 as cancer therapy.

The Application of Patient-Derived Xenograft Models in Gynecologic Cancers

Recently, due to the limitations of cell line models and animal models in the preclinical research with insufficient reflecting the physiological situation of humans, patient-derived xenograft (PDX) models of many cancers have been widely developed because of their better representation of the tumor heterogeneity and tumor microenvironment with retention of the cellular complexity, cytogenetics, and stromal architecture. PDX models now have been identified as a powerful tool for determining cancer characteristics, developing new treatment, and predicting drug efficacy. An increase in attempts to generate PDX models in gynecologic cancers has emerged in recent years to understand tumorigenesis. Hence, this review summarized the generation of PDX models and engraftment success of PDX models in gynecologic cancers. Furthermore, we illustrated the similarity between PDX model and original tumor, and described preclinical utilization of PDX models in gynecologic cancers. It would help supply better personalized therapy for gynecologic cancer patients.

Sorafenib Treatment and Modulation of the Sphingolipid Pathway Affect Proliferation and Viability of Hepatocellular Carcinoma In Vitro

Hepatocellular carcinoma (HCC) shows a remarkable heterogeneity and is recognized as a chemoresistant tumor with dismal prognosis. In previous studies, we observed significant alterations in the serum sphingolipids of patients with HCC. This study aimed to investigate the in vitro effects of sorafenib, which is the most widely used systemic HCC medication, on the sphingolipid pathway as well as the effects of inhibiting the sphingolipid pathway in HCC. Huh7.5 and HepG2 cells were stimulated with sorafenib, and inhibitors of the sphingolipid pathway and cell proliferation, viability, and concentrations of bioactive metabolites were assessed. We observed a significant downregulation of cell proliferation and viability and a simultaneous upregulation of dihydroceramides upon sorafenib stimulation. Interestingly, fumonisin B1 (FB1) and the general sphingosine kinase inhibitor SKI II were able to inhibit cell proliferation more prominently in HepG2 and Huh7.5 cells, whereas there were no consistent effects on the formation of dihydroceramides, thus implying an involvement of distinct metabolic pathways. In conclusion, our study demonstrates a significant downregulation of HCC proliferation upon sorafenib, FB1, and SKI II treatment, whereas it seems they exert antiproliferative effects independently from sphingolipids. Certainly, further data would be required to elucidate the potential of FB1 and SKI II as putative novel therapeutic targets in HCC.

KSP siRNA/paclitaxel-loaded PEGylated cationic liposomes for overcoming resistance to KSP inhibitors: Synergistic antitumor effects in drug-resistant ovarian cancer

Despite the promising anticancer effects of kinesin spindle protein (KSP) inhibition, functional plasticity of kinesins induced resistance against KSP inhibitors in a variety of cancers, leading to clinical failure. Additionally, paclitaxel is a widely used anticancer agent, but drug resistance has limited its use in the recurrent cancers. To overcome resistance against KSP inhibitors, we paired KSP inhibition with microtubule stabilization using KSP siRNA and paclitaxel. To enable temporal co-localization of both drugs in tumor cells in vivo, we exploited PEGylated cationic liposomes carrying both simultaneously. Drug synergism study shows that resistance against KSP inhibition can be suppressed by the action of microtubule-stabilizing paclitaxel, because microtubule stabilization prevents a different kinesin Kif15 from replacing all essential functions of KSP when KSP is inhibited. Our combination therapy showed more effective antiproliferative activity in vitro and in vivo than either paclitaxel or KSP siRNA alone. Ultimately, we could observe significantly improved therapeutic effects in the drug-resistant in vivo models, including cell line and patient-derived xenografts. Taken together, our combination therapy provides a potential anticancer strategy to overcome resistance against KSP inhibitors. Particularly, this strategy also provides an efficient approach to improve the therapeutic effects of paclitaxel in the drug-resistant cancers.

S1P Signaling in the Tumor Microenvironment

Sphingosine-1-phosphate (S1P), together with other phosphosphingolipids, has been found to regulate complex cellular function in the tumor microenvironment (TME) where it acts as a signaling molecule that participates in cell-cell communication. S1P, through intracellular and extracellular signaling, was found to promote tumor growth, angiogenesis, chemoresistance, and metastasis; it also regulates anticancer immune response, modulates inflammation, and promotes angiogenesis. Interestingly, cancer cells are capable of releasing S1P and thus modifying the behavior of the TME components in a way that contributes to tumor growth and progression. Therefore, S1P is considered an important therapeutic target, and several anticancer therapies targeting S1P signaling are being developed and tested in clinics.

OScc: an online survival analysis web server to evaluate the prognostic value of biomarkers in cervical cancer

Aim: To establish a web server that can mutually validate prognostic biomarkers of cervical cancer. Methods: Four datasets including expression profiling and relative clinical follow-up data were collected from Gene Expression Omnibus and The Cancer Genome Atlas. The web server was developed by R software. Results: The web server was named OScc including 690 patients and can be accessed at http://bioinfo.henu.edu.cn/CESC/CESCList.jsp . The Kaplan–Meier survival curves with log-rank p-value and hazard ratio will be generated of interested gene in OScc. Compared with previous predictive tools, OScc had the advantages of registration-free, larger sample size and subgroup analysis. Conclusion: The OScc is highly valuable to perform the preliminary assessment and validation of new or interested prognostic biomarkers for cervical cancer.

Phospho-Sphingosine Kinase 1 Expression in Lymphatic Spread of Esophageal Squamous Cell Carcinoma

BACKGROUND

Lymphatic spread is the main mode of progression of esophageal squamous cell carcinoma (ESCC). Sphingosine-1-phosphate (S1P) is a pleiotropic bioactive lipid mediator, which produced by sphingosine kinase 1 (SphK1) activated by phosphorylation. The SphK1-S1P axis has a crucial role in lymphangiogenesis. However, the significance of phospho-SphK1 (pSphK1) in the progression of ESCC has not been fully investigated.

MATERIALS AND METHODS

We evaluated pSphK1 expression in 92 surgically resected tumor tissues of ESCC by the immunohistochemistry. Fifty-nine (64%) patients with moderate or strong expression and 33 (36%) with negative or weak expression were classified in the pSphK1-high and pSphK1-low groups, respectively.

RESULTS

Higher pathological N category (pN) was more frequently observed in the pSphK1-high group (P < 0.01). The median number of lymph node metastasis (pSphK1-high: 2 versus pSphK1-low: 0; P < 0.01), the proportion of patients with lymphatic invasion (69% versus 18%; P < 0.01) and that with intramural metastasis (27% versus 3%; P < 0.01) were significantly higher in the pSphK1-high group. The presence of lymphatic invasion (odds ratio [OR] 5.63; P < 0.01) and pN1-3 (OR 3.26; P = 0.04) were independently associated with high pSphK1 expression. The 5-y overall survival rate of the pSphK1-high group was significantly lower than that of the pSphK1-low group (50.8% versus 67.3%; P = 0.01). High pSphK1 expression was not identified as a significant independent prognostic factor.

CONCLUSIONS

We provide the first evidence of the association between high expression of pSphK1 and both lymphatic spread and patient outcomes in ESCC.

NCK1 promotes the angiogenesis of cervical squamous carcinoma via Rac1/PAK1/MMP2 signal pathway

OBJECTIVE

The study was to explore the roles of Nck1 in the angiogenesis of cervical squamous cell carcinoma (CSCC).

METHODS

mRNA and protein levels were evaluated with real-time quantitative PCR and immunohistochemisty/western blotting respectively. The cancer microvessel density (MVD) was assayed with CD34 endothelial labeling. Nck1 gene knock-in (SiHa-Nck1+) and knock-down (SiHa-Nck1-) were achieved by gene transfection and siRNA respectively. Protein level from cellular supernatant was measured with ELISA. Proliferation, migration and tube formation of the Human Umbilical Vein Endothelial cells (HUVECs) were evaluated by CCK-8 cell viability assay, transwell chamber assay and in vitro Matrigel tubulation assay respectively.

RESULTS

Nck1 level gradually increased from normal cervical epithelia to high-grade CIN, overexpressed in CSCC and was associated with cancer MVD. The ability of proliferation, migration and tube formation of HUVECs was enhanced in SiHa-Nck1+-treated while decreased in SiHa-NcK1--treated cells compared to SiHa-control-treated cells. Mechanistically, RAC1-GTP, p-PAK1 and MMP2 were increased in SiHa-NCK1+ cells and pretreatment with the Rac1 inhibitor (NSC23766) significantly decreased their levels. Furthermore, inhibition of PAK1 reduced MMP2 level in SiHa-Nck1+ cells whereas the level of Rac1-GTP was unaltered. Also, inhibition of Rac1 or PAK1 impaired angiogenesis-inducing capacity of cancer cells.

CONCLUSIONS

Nck1 promotes the angiogenesis-inducing capacity of CSCC via the Rac1/PAK1/MMP2 signal pathway.

Down-regulation of HPGD by miR-146b-3p promotes cervical cancer cell proliferation, migration and anchorage-independent growth through activation of STAT3 and AKT pathways

While the application of early screening and HPV vaccines has reduced the incidence and mortality rates of cervical cancer, it remains the third most common carcinoma and fourth leading cause of cancer-associated death among women worldwide. The precise mechanisms underlying progression of cervical cancer are not fully understood at present. Here, we detected significant down-regulation of 15-hydroxyprostaglandin dehydrogenase (HPGD) in cervical cancer tissues. Overexpression of HPGD inhibited cervical cancer cell proliferation, migration and anchorage-independent growth to a significant extent. To clarify the mechanisms underlying HPGD down-regulation in cervical cancer, miRNA microarray, bioinformatics and luciferase reporter analyses were performed. HPGD was identified as a direct target of miR-146b-3p displaying up-regulation in cervical cancer tissues. Similar to the effects of HPGD overexpression, down-regulation of miR-146b-3p strongly suppressed proliferation, migration and anchorage-independent growth of cervical cancer cells. Furthermore, HPGD negatively regulated activities of STAT3 and AKT that promote cervical cancer cell proliferation. Notably, HPV oncogenes E6 and E7 were determined as potential contributory factors to these alterations. Our results collectively suggest that the HPGD/miR-146b-3p axis plays a significant role in cervical cancer and may serve as a potentially effective therapeutic target.

Investigation of PP2A and Its Endogenous Inhibitors in Neuroblastoma Cell Survival and Tumor Growth

High-risk neuroblastoma continues to carry a poor prognosis. Nearly 50% of these tumors relapse following extensive treatment regimens. Protein phosphatase 2A (PP2A), a tumor suppressor, has been shown to be downregulated in many human cancers via multiple mechanisms including upregulation of its endogenous inhibitors, I2PP2A or CIP2A. We hypothesized that inhibition of the endogenous PP2A inhibitors or activation of PP2A would decrease tumorigenicity in human neuroblastoma cells. Four human neuroblastoma cell lines were utilized. Expression of PP2A and its endogenous inhibitors I2PP2A and CIP2A was confirmed by immunoblotting. PP2A activation was measured via phosphatase activation assay. Multiple parallel methods including siRNA inhibition of the endogenous PP2A inhibitors and pharmacologic activation of PP2A were utilized. Cell viability, proliferation, migration, and invasion assays were performed. In vivo studies were utilized to determine the effects of PP2A activation on neuroblastoma tumor growth. Inhibition of the endogenous inhibitors of PP2A or pharmacologic activation of PP2A with the PP2A activator FTY720 led to decreased neuroblastoma cell viability, proliferation, migration, and invasion. Treatment of mice bearing SK-N-AS or SK-N-BE(2) neuroblastoma tumors with FTY720 resulted in a significant decrease in tumor growth compared to vehicle-treated animals. In conclusion, activation of PP2A may provide a novel therapeutic target for neuroblastoma.

Sphingolipid metabolism and drug resistance in ovarian cancer

Despite progress in understanding molecular aberrations that contribute to the development and progression of ovarian cancer, virtually all patients succumb to drug resistant disease at relapse. Emerging data implicate bioactive sphingolipids and regulation of sphingolipid metabolism as components of response to chemotherapy or development of resistance. Increases in cytosolic ceramide induce apoptosis in response to therapy with multiple classes of chemotherapeutic agents. Aberrations in sphingolipid metabolism that accelerate the catabolism of ceramide or that prevent the production and accumulation of ceramide contribute to resistance to standard of care platinum- and taxane-based agents. The aim of this review is to highlight current literature and research investigating the influence of the sphingolipids and enzymes that comprise the sphingosine-1-phosphate pathway on the progression of ovarian cancer. The focus of the review is on the utility of sphingolipid-centric therapeutics as a mechanism to circumvent drug resistance in this tumor type.

CD44-Targeting PLGA Nanoparticles Incorporating Paclitaxel and FAK siRNA Overcome Chemoresistance in Epithelial Ovarian Cancer

Chemotherapy is commonly used in the treatment of ovarian cancer, yet most ovarian cancers harbor inherent resistance or develop acquired resistance. Therefore, novel therapeutic approaches to overcome chemoresistance are required. In this study, we developed a hyaluronic acid-labeled poly(d,l-lactide-co-glycolide) nanoparticle (HA-PLGA-NP) encapsulating both paclitaxel (PTX) and focal adhesion kinase (FAK) siRNA as a selective delivery system against chemoresistant ovarian cancer. The mean size and zeta potential of the HA-PLGA-NP were 220 nm and -7.3 mV, respectively. Incorporation efficiencies for PTX and FAK siRNA in the HA-PLGA-NPs were 77% and 85%, respectively. HA-PLGA-NP showed higher binding efficiency for CD44-positive tumor cells as compared with CD44-negative cells. HA-PLGA (PTX+FAK siRNA)-NP caused increased cytotoxicity and apoptosis in drug-resistant tumor cells. Treatment of human epithelial ovarian cancer tumor models HeyA8-MDR (P < 0.001) and SKOV3-TR (P < 0.001) with HA-PLGA (PTX+FAK siRNA)-NP resulted in significant inhibition of tumor growth. Moreover, in a drug-resistant, patient-derived xenograft (PDX) model, HA-PLGA (PTX+FAK siRNA)-NP significantly inhibited tumor growth compared with PTX alone (P < 0.002). Taken together, HA-PLGA-NP acts as an effective and selective delivery system for both the chemotherapeutic and the siRNA in order to overcome chemoresistance in ovarian carcinoma.Significance: These findings demonstrate the efficacy of a novel, selective, two-in-one delivery system to overcome chemoresistance in epithelial ovarian cancer. Cancer Res; 78(21); 6247-56. ©2018 AACR.

FTY720 Decreases Tumorigenesis in Group 3 Medulloblastoma Patient-Derived Xenografts

Group 3 tumors account for 28% of medulloblastomas and have the worst prognosis. FTY720, an immunosuppressant currently approved for treatment of multiple sclerosis, has shown antitumor effects in several human cancer cell lines. We hypothesized that treatment with FTY720 (fingolimod) would decrease tumorigenicity in medulloblastoma patient-derived xenografts (PDXs). Three Group 3 medulloblastoma PDXs (D341, D384 and D425) were utilized. Expression of PP2A and its endogenous inhibitors I2PP2A and CIP2A was detected by immunohistochemistry and immunoblotting. PP2A activation was measured via phosphatase activation kit. Cell viability, proliferation, migration and invasion assays were performed after treatment with FTY720. Cell cycle analysis was completed using flow cytometry. A flank model using D425 human medulloblastoma PDX cells was used to assess the in vivo effects of FTY720. FTY720 activated PP2A and led to decreased medulloblastoma PDX cell viability, proliferation, migration and invasion and G1 cell cycle arrest in all three PDXs. FTY720 treatment of mice bearing D425 medulloblastoma PDX tumors resulted in a significant decrease in tumor growth compared to vehicle treated animals. FTY720 decreased viability, proliferation, and motility in Group 3 medulloblastoma PDX cells and significantly decreased tumor growth in vivo. These results suggest that FTY720 should be investigated further as a potential therapeutic agent for medulloblastoma.

Biomarkers could facilitate prediction of worse clinical outcome of cancer with special insight to cervical cancer

Cervical cancer incidence, globally, is second only to malignant breast cancer. The main causative factor is thought to be human papillomavirus (HPV) infection as a result of many sexual partners. Despite radiotherapy, chemotherapy and surgical treatment, the survival rate of patients with advanced disease is low. Metastasis is one of the stages of cancerogenesis in which tumour cells acquire the ability to migrate and create tumour secondary foci. Tumour biomarkers, proteins produced by neoplastic cells, quantified in body fluids or in tissues, play a key role in treatment monitoring and in determining the prognosis for further years of life. In recent years, the search for cervical cancer biomarkers has been intensively sought. They can become a decisive factor in making radical treatment and, in the near future, a potential therapeutic goal. The article presents and briefly describes the biomarkers of metastasis in cervical cancer studied in recent years and highlights their potential therapeutic use.

More than Just an Immunosuppressant: The Emerging Role of FTY720 as a Novel Inducer of ROS and Apoptosis

Fingolimod hydrochloride (FTY720) is a first-in-class of sphingosine-1-phosphate (S1P) receptor modulator approved to treat multiple sclerosis by its phosphorylated form (FTY720-P). Recently, a novel role of FTY720 as a potential anticancer drug has emerged. One of the anticancer mechanisms of FTY720 involves the induction of reactive oxygen species (ROS) and subsequent apoptosis, which is largely independent of its property as an S1P modulator. ROS have been considered as a double-edged sword in tumor initiation/progression. Intriguingly, prooxidant therapies have attracted much attention due to its efficacy in cancer treatment. These strategies include diverse chemotherapeutic agents and molecular targeted drugs such as sulfasalazine which inhibits the CD44v-xCT (cystine transporter) axis. In this review, we introduce our recent discoveries using a chemical genomics approach to uncover a signaling network relevant to FTY720-mediated ROS signaling and apoptosis, thereby proposing new potential targets for combination therapy as a means to enhance the antitumor efficacy of FTY720 as a ROS generator. We extend our knowledge by summarizing various measures targeting the vulnerability of cancer cells' defense mechanisms against oxidative stress. Future directions that may lead to the best use of FTY720 and ROS-targeted strategies as a promising cancer treatment are also discussed.

The association of pretreatment thrombocytosis with prognosis and clinicopathological significance in cervical cancer: a systematic review and meta-analysis

Previous studies reported inconsistent findings about the relationship between pretreatment thrombocytosis and survival in patients with cervical cancer. This study aimed to evaluate the prognostic significance of thrombocytosis in cervical cancer. We searched databases to identify relevant articles. Pooled hazard ratios (HRs), odds ratios (ORs), and 95% confidence intervals (CIs) were calculated. Fourteen studies including 3,394 patients were eligible for the meta-analysis. Overall, an elevated platelet count was significantly associated with inferior overall survival (OS, hazard ratio [HR]: 1.66, 95% confidence interval [CI]: 1.42–1.95, P < 0.001) and recurrence-free survival (RFS, HR: 1.67, 95% CI: 1.15–2.42, P = 0.007) but not progression-free survival (PFS, HR: 1.21, 95% CI: 0.89–1.64; P = 0.235). The results were similar for low stage patients treated with surgery alone. Moreover, a pretreatment thrombocytosis status was significantly associated with higher clinical stage (odd ratio [OR]: 2.39, 95% CI: 1.68–3.38, P < 0.001), positive pelvic node status (OR: 1.58, 95% CI: 1.01– 2.45, P = 0.044) and larger tumor size (OR: 2.32, 95% CI: 1.39–3.87, P = 0.001). Pretreatment thrombocytosis is an independent prognosis predictor in cervical cancer patients. It may be used as a readily available biomarker to refine clinical outcome prediction for cervical cancer patients.

Stromal p16 expression is significantly increased in malignant ovarian neoplasms

Alterations in p16 protein expression have been reported to be associated with tumor development and progression. However, p16 expression status in the peritumoral stroma has been rarely investigated. We investigated the stromal p16 expression in ovarian neoplasms using immunohistochemistry, and differences in the expression status depending on the degree of malignancy and histological type were analyzed. This study included 24, 21, and 46 cases of benign, borderline, and malignant ovarian lesions, respectively, of which 29, 25, and 32 cases were serous, mucinous, and endometriosis-associated lesions. Most benign lesions showed negative or weak expression, whereas borderline lesions showed focal, moderate expression. Malignant lesions showed markedly elevated stromal p16 expression compared with benign or borderline lesions. There were significant differences in stromal p16 expression between benign and borderline lesions (P < 0.001) and between borderline and malignant lesions (P < 0.001). These significances remained when analysis was performed based on lesion classification as serous, mucinous, and endometriosis-associated. In contrast, differences in stromal p16 expression among the histological types were not significant. Stromal p16 expression in ovarian neoplasms was absent or weak in benign and focal, moderate in borderline lesions, whereas malignant lesions exhibited diffuse, moderate-to-strong p16 immunoreactivity. Our observations suggest that stromal p16 expression is involved in the development of ovarian carcinoma. Further studies are necessary to confirm our preliminary results.

Sphk1 promotes breast epithelial cell proliferation via NF-κB-p65-mediated cyclin D1 expression

Lipid metabolism is crucially involved with the promotion of malignant progression and metastasis in various cancers. Growing evidence suggests that many types of cancers express high levels of sphingosine kinase 1 (Sphk1), which is known to mediate cell proliferation We hypothesized that Sphk1/sphingosine-1-phosphate (S1P) signaling contributes to tumor progression. In MCF10A and MCF10A-Sphk1 breast epithelial cells, we used TNF-α to activate the Sphk1/S1P pathway and the measured expression levels of NF-κBp65 and cyclin D1 mRNA and protein in the presence and absence of an NF-κB-p65 inhibitor. Chromatin immunoprecipitation assays were performed to determine whether NF-κB-p65 binds to the cyclin D1 promoter. We found that overexpression of Sphk1 induced NF-κB-p65 activation, increased expression of cyclin D1, shortened the cell division cycle, and thus promoted proliferation of breast epithelial cells. These findings provide insight into the mechanism by which an Sphk1/NF-κB-p65/cyclin D1 signaling pathway mediates cell proliferation.

Stromal p16 expression is significantly increased in endometrial carcinoma

p16 is a negative regulator of cell proliferation and is considered a tumor suppressor protein. Alterations in p16 protein expression are associated with tumor development and progression. However, the p16 expression status in the peritumoral stroma has not been investigated in the endometrium. Therefore, we evaluated stromal p16 expression in different types of endometrial lesions using immunohistochemistry. Differences in the p16 expression status according to the degree of malignancy and histological type were analyzed. This study included 62, 26, and 36 cases of benign, precancerous, and malignant endometrial lesions, respectively. Most benign lesions showed negative or weak expression, whereas precancerous lesions showed a variable degree of staining proportion and intensity. Atypical hyperplasia/endometrial intraepithelial neoplasia (AH/EIN) and serous endometrial intraepithelial carcinoma (SEIC) had significantly higher stromal p16 expression levels than benign lesions. Endometrioid carcinoma (EC), serous carcinoma (SC), and carcinosarcoma showed significantly elevated stromal p16 expression levels compared with benign and precancerous lesions. In addition, there were significant differences in stromal p16 expression between AH/EIN and SEIC and between EC and SC. In contrast, differences in stromal p16 expression among nonpathological endometrium, atrophic endometrium, endometrial polyp, and hyperplasia without atypia were not statistically significant. Our observations suggest that stromal p16 expression is involved in the development and progression of endometrial carcinoma, and raise the possibility that p16 overexpression in the peritumoral stroma is associated with aggressive oncogenic behavior of endometrial SC.

Sphingosine kinase 2 supports the development of BCR/ABL-independent acute lymphoblastic leukemia in mice

Background

Sphingosine kinase (SphK) 2 has been implicated in the development of a range of cancers and inhibitors of this enzyme are currently in clinical trial. We have previously demonstrated a role for SphK2 in the development of acute lymphoblastic leukemia (ALL).

Methods

In this and our previous study we use mouse models: in the previous study the disease was driven by the proto-oncogene BCR/ABL1, while in this study cancer risk was elevated by deletion of the tumor suppressor ARF.

Results

Mice lacking ARF and SphK2 had a significantly reduced incidence of ALL compared mice with wild type SphK2.

Conclusions

These results show that the role of SphK2 in ALL development is not limited to BCR/ABL1 driven disease extending the potential use of inhibitors of this enzyme to ALL patients whose disease have driver mutations other than BCR/ABL1.

The sphingosine kinase 2 inhibitor ABC294640 inhibits cervical carcinoma cell growth

ABC294640 is a specific sphingosine kinase 2 (SphK2) inhibitor. The anti-cervical carcinoma activity by ABC294640 was tested in this study. ABC294640 inhibited in vitro growth of the established (C33A and HeLa lines) and primary human cervical carcinoma cells. The SphK2 inhibitor also induced G1-S arrest and apoptosis in cervical carcinoma cells. It was yet non-cytotoxic to SphK2-low human cervical epithelial cells. ABC294640 inhibited SphK activation, causing sphingosine-1-phosphate depletion, signal transducer and activator of transcription 3 in-activation and ceramide production. Bcl-2 is a key resistance factor of ABC294640. Pharmacological Bcl-2 inhibition or Bcl-2 shRNA potentiated ABC294640-induced C33A cell growth inhibition and apoptosis. On the other hand, exogenous over-expression of Bcl-2 attenuated ABC294640's cytotoxicity against C33A cells. In vivo, ABC294640 administration inhibited C33A xenograft tumor growth in mice. Co-administration of the Bcl-2 inhibitor GDC-0199 further potentiated ABC294640's anti-tumor activity. Together, we suggest that ABC294640 might have translational value for the treatment of human cervical carcinoma.

Predictive and prognostic value of sphingosine kinase 1 expression in patients with invasive ductal carcinoma of the breast

Sphingosine kinase 1 (SPHK1) has been found to be upregulated in many different types of human malignancy and plays a crucial role in cancer development and progression. However, the potential of SPHK1 to act as a predictive and prognostic biomarker in breast cancer remains to be clarified. In the present study, SPHK1 expression was evaluated in breast cancer cell lines and 224 breast cancer tissue samples using immunohistochemical staining. Compared to the normal mammary epithelial cell line MCF-10A, SPHK1 mRNA and protein expression levels increased in the breast cancer cell lines SK-BR-3, MDA-MB-231, MDA-MB-436, and MCF-7. Immunohistochemical staining revealed SPHK1 expression to be significantly increased in breast cancer tissue compared to normal breast tissue, with 85 (37.9%) of the 224 invasive ductal carcinomas (IDC) exhibiting high SPHK1 expression. High SPHK1 expression in IDC showed a significant association with higher histological grade, distant metastasis, and triple negativity, and was shown to be an independent predictor for distant metastasis development. In addition, patients with high SPHK1 expression had significantly lower progression-free survival and overall survival rates compared to those with low SPHK1 expression. Our data suggest that SPHK1 is involved in the development and progression of breast cancer and can serve as a potential predictive biomarker of distant metastasis and patient outcome.

SHH gene silencing suppresses epithelial-mesenchymal transition, proliferation, invasion, and migration of cervical cancer cells by repressing the hedgehog signaling pathway

The study aimed to investigate the mechanism by which the sonic Hedgehog (SHH) gene silencing acts upon epithelial-mesenchymal transition (EMT), proliferation, invasion, and migration of cervical cancer (CC) cells via the Hedgehog signaling pathway. RT-qPCR and Western blotting were all employed to detect the SHH mRNA and protein expressions. HeLa and CasKi cells were cultured and subsequently divided into the blank, negative control (NC), and SHH-RNAi groups. A cell counting kit-8 (CCK-8) assay was utilized for cell proliferation. Cell migration and invasion ability were evaluated through scratching test and Transwell assay. The mRNA and protein expressions of the Hedgehog signaling pathway-related factors were detected using RT-qPCR and Western blotting, respectively. After tumor xenograft in nude mice, tumor growth was subsequently observed. SHH mRNA and protein expressions were greater in the SHH-RNAi group than in the blank and NC groups. Compared with the blank group and NC groups, the SHH-RNAi group displayed inhibited levels of proliferation, migration, invasion abilities, as well as a decreased in the Hh signaling pathway-related factors, as well as a reduction in the mRNA and protein expressions of N-cadherin and Vimentin, however, on the contrary increased expressions of E-cadherin were observed. Following tumor xenograft in nude mice, tumor growth was exhibited vast levels of inhibition, particularly in the SHH-RNAi group in comparison to the blank and the NC groups. During the study it was well established that SHH gene silencing suppresses EMT, proliferation, invasion, and migration of CC cells through the repression of the Hedgehog signaling pathway.

"Dicing and Splicing" Sphingosine Kinase and Relevance to Cancer

Sphingosine kinase (SphK) is a lipid enzyme that maintains cellular lipid homeostasis. Two SphK isozymes, SphK1 and SphK2, are expressed from different chromosomes and several variant isoforms are expressed from each of the isozymes, allowing for the multi-faceted biological diversity of SphK activity. Historically, SphK1 is mainly associated with oncogenicity, however in reality, both SphK1 and SphK2 isozymes possess oncogenic properties and are recognized therapeutic targets. The absence of mutations of SphK in various cancer types has led to the theory that cancer cells develop a dependency on SphK signaling (hyper-SphK signaling) or “non-oncogenic addiction”. Here we discuss additional theories of SphK cellular mislocation and aberrant “dicing and splicing” as contributors to cancer cell biology and as key determinants of the success or failure of SphK/S1P (sphingosine 1 phosphate) based therapeutics.

B-cell translocation gene 1 is downregulated by promoter methylation in ovarian carcinoma

A better understanding of tumor biology is important in the identification of molecules that are downregulated in malignancy and in determining their role in tumor suppression. B-cell translocation gene 1 (BTG1) has been shown to act as a tumor suppressor in several types of human malignancy. In this study, we analyzed BTG1 expression in ovarian carcinoma cell lines, and we investigated the mechanism underlying the observed alterations. The methylation status of the BTG1 promoter region was determined by methylation-specific polymerase chain reaction, and the effect of demethylation on BTG1 expression was analyzed. BTG1 protein expression in ovarian high-grade serous carcinoma tissue samples was evaluated using immunohistochemistry. BTG1 mRNA and protein expression were reduced in ovarian carcinoma cells. In BTG1-silenced ovarian cancer cells, the BTG1 promoter was highly methylated. Treatment with 5-aza-deoxycytidine significantly elevated BTG1 mRNA and protein expression. Immunostaining demonstrated that BTG1 expression was significantly lower in ovarian carcinoma tissue samples than nonpathological ovaries and fallopian tubes. We demonstrated that BTG1 silencing in ovarian carcinoma occurs through epigenetic repression and is involved in the ovarian carcinogenesis. Our data suggest that BTG1 is a potential therapeutic target for patients with ovarian carcinoma.

Prognostic value of the pretreatment neutrophil-to-lymphocyte ratio in cervical cancer: a meta-analysis and systematic review

The prognostic value of pretreatment neutrophil-to-lymphocyte ratio (NLR) in cervical cancer remains controversial. We conducted a meta-analysis based on the data from 13 studies with 3729 patients to evaluate the association between the pretreatment NLR and the clinical outcomes of overall survival and progression-free survival in patients with cervical cancer. The relationship between NLR and clinicopathological parameters was also assessed. Hazard ratio (HR) or odds ratio (OR) with its 95% confidence interval (CI) was used as the effect size estimate. Our analysis indicated that elevated pretreatment NLR was a poor prognostic marker for patients with cervical cancer because it predicted unfavorable overall survival (HR = 1.375, 95% CI: 1.200–1.576) and progression-free survival (HR = 1.646, 95% CI: 1.313–2.065). Increased NLR is also significantly associated with the larger tumor size (OR = 1.780, 95% CI: 1.090–2.908), advanced clinical stage (OR = 2.443, 95% CI: 1.730–3.451), and positive lymph node metastasis (OR = 2.380, 95% CI: 1.775–3.190). By these results, high pretreatment NLR predicted a shorter survival period for patients with cervical cancer, and it could be served as a novel index of prognostic evaluation in patients with cervical cancer.

Inhibition of basal-like breast cancer growth by FTY720 in combination with epidermal growth factor receptor kinase blockade

BACKGROUND

New molecular targets are needed for women with triple-negative breast cancer (TNBC). This pre-clinical study investigated the combination of the EGFR inhibitor gefitinib with the sphingosine kinase (SphK) inhibitor FTY720 (Fingolimod), aiming to block tumorigenic signaling downstream of IGFBP-3, which is abundantly expressed in basal-like TNBC.

METHODS

In studies of breast cancer cell growth in culture, proliferation was monitored by IncuCyte live-cell imaging, and protein abundance was determined by western blotting. In vivo studies of mammary tumor growth used two models: orthotopic xenograft tumors derived from three basal-like TNBC cell lines, grown in immune-deficient mice, and syngeneic murine 4T1 tumors grown in immune-competent mice. Protein abundance in tumor tissue was assessed by immunohistochemistry.

RESULTS

Quantitated by live-cell imaging, the inhibitor combination showed synergistic cytostatic activity in basal-like cell lines across several TNBC molecular subtypes, the synergy being decreased by IGFBP-3 downregulation. Suppression of the tumorigenic mediator CD44 by gefitinib was potentiated by FTY720, consistent with CD44 involvement in the targeted pathway. In MDA-MB-468 and HCC1806 orthotopic TNBC xenograft tumors in nude mice, the drug combination inhibited tumor growth and prolonged mouse survival, although this effect was not significant for the gefitinib-resistant cell line HCC70. Combination treatment of murine 4T1 TNBC tumors in syngeneic BALB/c mice was more effective in immune-competent than immune-deficient (nude) mice, and a relative loss of tumor CD3 (T-cell) immunoreactivity caused by FTY720 treatment alone was alleviated by the drug combination, suggesting that, even at an FTY720 dose causing relative lymphopenia, the combination is still effective in an immune-competent setting. Immunohistochemistry of xenograft tumors showed significant enhancement of caspase-3 cleavage and suppression of Ki67 and phospho-EGFR by the drug combination, but SphK1 downregulation occurred only in MDA-MB-468 tumors, so is unlikely to be integral to treatment efficacy.

CONCLUSIONS

Our data indicate that targeting IGFBP-3-dependent signaling pathways through gefitinib-FTY720 co-therapy may be effective in many basal-like breast cancers, and suggest tissue IGFBP-3 and CD44 measurement as potential biomarkers of treatment efficacy.

Mammalian sphingosine kinase (SphK) isoenzymes and isoform expression: challenges for SphK as an oncotarget

The various sphingosine kinase (SphK) isoenzymes (isozymes) and isoforms, key players in normal cellular physiology, are strongly implicated in cancer and other diseases. Mutations in SphKs, that may justify abnormal physiological function, have not been recorded. Nonetheless, there is a large and growing body of evidence demonstrating the contribution of gain or loss of function and the imbalance in the SphK/S1P rheostat to a plethora of pathological conditions including cancer, diabetes and inflammatory diseases. SphK is expressed as two isozymes SphK1 and SphK2, transcribed from genes located on different chromosomes and both isozymes catalyze the phosphorylation of sphingosine to S1P. Expression of each SphK isozyme produces alternately spliced isoforms. In recent years the importance of the contribution of SpK1 expression to treatment resistance in cancer has been highlighted and, additionally, differences in treatment outcome appear to also be dependent upon SphK isoform expression. This review focuses on an exciting emerging area of research involving SphKs functions, expression and subcellular localization, highlighting the complexity of targeting SphK in cancer and also comorbid diseases. This review also covers the SphK isoenzymes and isoforms from a historical perspective, from their first discovery in murine species and then in humans, their role(s) in normal cellular function and in disease processes, to advancement of SphK as an oncotarget.

Overexpression of sphingosine kinase 1 is predictive of poor prognosis in human breast cancer

Sphingosine kinase 1 (SPHK1) is a bioactive lipid mediator that has been identified as a biomarker in various cancers and is considered to play an important role in tumor progression. In the present study, the expression level of SPHK1 was examined in breast cancer clinical specimens, and its association with patient survival was investigated to clarify the clinical significance of SPHK1 in breast cancer. SPHK1 mRNA expression was increased in breast cancer tissues compared with that in matched adjacent breast tissues in 19 of 32 paired tissue specimens (59.4%). Immunohistochemical analysis of 122 breast cancer cases revealed that the expression levels of SPHK1 were upregulated in 64 tumor tissues (52.5%), and increased expression levels of the protein were significantly associated with the presence of lymph node metastasis (P=0.0016), number of positive lymph nodes (P=0.0268) and presence of distant metastasis (P=0.0097). Increased SPHK1 protein expression was also associated with human epidermal growth factor receptor 2 status (P=0.0100), initial symptoms (P=0.0025) and tumor location (P=0.0457). Patients with increased SPHK1 protein expression had shorter overall survival and disease-free survival times compared with patients with lower SPHK1. Univariate and multivariate analyses indicated that high SPHK1 expression may be a poor prognostic factor. These results indicated that SPHK1 may perform an important role in breast cancer and may be a predictive factor in patients with breast cancer.

NMR metabolomics highlights sphingosine kinase-1 as a new molecular switch in the orchestration of aberrant metabolic phenotype in cancer cells

Strong experimental evidence in animal and cellular models supports a pivotal role of sphingosine kinase‐1 (SK1) in oncogenesis. In many human cancers, SK1 levels are upregulated and these increases are linked to poor prognosis in patients. Here, by employing untargeted NMR‐based metabolomic profiling combined with functional validations, we report the crucial role of SK1 in the metabolic shift known as the Warburg effect in A2780 ovarian cancer cells. Indeed, expression of SK1 induced a high glycolytic rate, characterized by increased levels of lactate along with increased expression of the proton/monocarboxylate symporter MCT1, and decreased oxidative metabolism, associated with the accumulation of intermediates of the tricarboxylic acid cycle and reduction in CO₂ production. Additionally, SK1‐expressing cells displayed a significant increase in glucose uptake paralleled by GLUT3 transporter upregulation. The role of SK1 is not limited to the induction of aerobic glycolysis, affecting metabolic pathways that appear to support the biosynthesis of macromolecules. These findings highlight the role of SK1 signaling axis in cancer metabolic reprogramming, pointing out innovative strategies for cancer therapies.

FTY720 inhibits mesothelioma growth in vitro and in a syngeneic mouse model

BACKGROUND

Malignant mesothelioma (MM) is a very aggressive type of cancer, with a dismal prognosis and inherent resistance to chemotherapeutics. Development and evaluation of new therapeutic approaches is highly needed. Immunosuppressant FTY720, approved for multiple sclerosis treatment, has recently raised attention for its anti-tumor activity in a variety of cancers. However, its therapeutic potential in MM has not been evaluated yet.

METHODS

Cell viability and anchorage-independent growth were evaluated in a panel of MM cell lines and human mesothelial cells (HM) upon FTY720 treatment to assess in vitro anti-tumor efficacy. The mechanism of action of FTY720 in MM was assessed by measuring the activity of phosphatase protein 2A (PP2A)-a major target of FTY720. The binding of the endogenous inhibitor SET to PP2A in presence of FTY720 was evaluated by immunoblotting and immunoprecipitation. Signaling and activation of programmed cell death were evaluated by immunoblotting and flow cytometry. A syngeneic mouse model was used to evaluate anti-tumor efficacy and toxicity profile of FTY720 in vivo.

RESULTS

We show that FTY720 significantly suppressed MM cell viability and anchorage-independent growth without affecting normal HM cells. FTY720 inhibited the phosphatase activity of PP2A by displacement of SET protein, which appeared overexpressed in MM, as compared to HM cells. FTY720 promoted AKT dephosphorylation and Bcl-2 degradation, leading to induction of programmed cell death, as demonstrated by caspase-3 and PARP activation, as well as by cytochrome c and AIF intracellular translocation. Moreover, FTY720 administration in vivo effectively reduced tumor burden in mice without apparent toxicity.

CONCLUSIONS

Our preclinical data indicate that FTY720 is a potentially promising therapeutic agent for MM treatment.

A novel sphingosine kinase 1 inhibitor (SKI-5C) induces cell death of Wilms' tumor cells in vitro and in vivo

Sphingosine kinase 1 (SphK1) is over-expressed in many cancers and therefore serves as a biomarker for cancer prognosis. SKI-5C is a new SphK1 inhibitor, and until now its molecular function in Wilms' tumor cells remained unknown. Here, using CCK-8 and nude mice experiments we assessed cell growth in Wilms' tumor cell lines (SK-NEP-1 and G401) in vitro and in vivo. We demonstrated that SphK1 is highly expressed in SK-NEP-1 and G401 cells, and through annexin V/propidium iodide staining and flow cytometry analysis, we detected cell apoptosis. Treatment with SKI-5C inhibited proliferation and induced apoptosis of SK-NEP-1 and G401 cells in a dose-dependent manner. Moreover, SKI-5C treatment inhibited the growth of SK-NEP-1 xenograft tumors in nude mice, with few side effects. Our microarray analysis revealed that SKI-5C-treated SK-NEP-1 cells mostly downregulated PRKACA and significantly inhibited phosphorylation of ERK1/2 and NF-κB p65. These results imply that SKI-5C induces apoptosis of SK-NEP-1 cells through the PRKACA/MAPK/NF-κB pathway. While, further research is required to determine the underlying details, these results provide new clues for the molecular mechanism of cell death induced by SKI-5C and suggest that SKI-5C may act as new candidate drug for Wilms' tumor.

Sphingosine-1 Phosphate: A New Modulator of Immune Plasticity in the Tumor Microenvironment

In the last 15 years, increasing evidences demonstrate a strong link between sphingosine-1-phosphate (S1P) and both normal physiology and progression of different diseases, including cancer and inflammation. Indeed, numerous studies show that tissue levels of this sphingolipid metabolite are augmented in many cancers, affecting survival, proliferation, angiogenesis, and metastatic spread. Recent insights into the possible role of S1P as a therapeutic target has attracted enormous attention and opened new opportunities in this evolving field. In this review, we will focus on the role of S1P in cancer, with particular emphasis in new developments that highlight the many functions of this sphingolipid in the tumor microenvironment. We will discuss how S1P modulates phenotypic plasticity of macrophages and mast cells, tumor-induced immune evasion, differentiation and survival of immune cells in the tumor milieu, interaction between cancer and stromal cells, and hypoxic response.

Increased expression of SKP2 is an independent predictor of locoregional recurrence in cervical cancer via promoting DNA-damage response after irradiation

Although radiation therapy was known to be effective to cervical cancer, loco-regional recurrences are frequently found in patients. We aimed to identify a molecular marker predicting the response of cervical cancer to radiotherapy. We included the patients (n = 149) with cervical cancer who had undergone radiotherapy from 2004 to 2006. Tumor samples were collected to examine the association between the expression of S-phase kinase-associated protein 2 (SKP2) and prognosis in cervical cancer. We found higher expression of SKP2 associated with recurrence (HRs: 2.52, p < 0.001), death (HRs: 2.01, p < 0.001) and higher locoregional recurrence rate (HRs: 3.76, p < 0.001). Cervical cancer cell lines with higher expression of SKP2 showed higher colony formation, cell survival rate and fewer DNA damages after irradiation. SKP2-C25, an inhibitor for SKP2 activity, dose-dependently decreased cell viability after irradiation and knockdown of SKP2 impaired DNA-damage response and sensitized the cervical cancer cells to irradiation. Our data showed the SKP2 represents a promising tool to identify patients with cervical cancer who have a higher risk of locoregional recurrence after radiotherapy. Targeting SKP2 may serve as a potential radiosensitizer for developing effective therapeutic strategies against cervical cancer.

Clinical Trials of Antiangiogenesis Therapy in Recurrent/Persistent and Metastatic Cervical Cancer

BACKGROUND

Treatment options for women with metastatic, persistent, or recurrent cervical cancer are limited and thus the disease portends a poor prognosis. It is critical to understand the pathophysiology of cervical cancer to better delineate therapeutic targets. The development of antiangiogenic therapies and their subsequent analysis in rigorous therapeutic trials have redefined current management strategies and is an exciting area of current exploration.

RESULTS

Translational trials have furthered the understanding of molecular determinants of angiogenesis. Phase II trials have shown promising trends with developing antiangiogenic therapies. A practice-changing phase III trial has recently been published. Given the potential benefits and different toxicity spectrum compared with standard cytotoxic chemotherapy, antiangiogenic options are under active investigation for this vulnerable patient population. Emerging data are promising for other antiangiogenic-directed therapeutics, as well as cervical cancer molecular biomarkers to guide diagnosis and treatment.

CONCLUSION

Antiangiogenic therapies have evolved during the past 20 years and remain an exciting area of current exploration.

IMPLICATIONS FOR PRACTICE

Understanding of the angiogenic microenvironment has furthered understanding of tumor biology and management. Antiangiogenic therapies show promise for women with advanced cervical cancer. A review of the evolution of these biologic agents shows them to be an effective and tolerable management strategy for many patients in this vulnerable population, with exciting future potential.

Overexpression of SphK1 enhances cell proliferation and invasion in triple-negative breast cancer via the PI3K/AKT signaling pathway

Sphingosine kinase 1 (SphK1) expression is elevated in various cancers and is associated with shorter survival times for patients. However, the molecular mechanism of SphK1 up-regulation in triple-negative breast cancer (TNBC) remains unclear. In this study, we assayed the expression level of SphK1 in TNBC tissues by qRT-PCR and immunohistochemistry. The level of S1P was quantified by ELISA in the serum of TNBC patients. Our results found that the levels of SphK1 and S1P were significantly increased in TNBC patients compared with normal control. Furthermore, knockdown of SphK1 with siRNA decreased TNBC cell proliferation and inhibited cell migration/invasion. These data suggest that SphK1 has an important role in TNBC and presents an attractive therapeutic target for the treatment for TNBC.