Additive effect of apicidin and doxorubicin in sulfatase 1 expressing hepatocellular carcinoma in vitro and in vivo

6-O-endosulfatases in tumor metastasis: heparan sulfate proteoglycans modification and potential therapeutic targets

Metastasis is the leading cause of cancer-associated mortality. Although advances in the targeted treatment and immunotherapy have improved the management of some cancers, the prognosis of metastatic cancers remains unsatisfied. Therefore, the specific mechanisms in tumor metastasis need further investigation. 6-O-endosulfatases (SULFs), comprising sulfatase1 (SULF1) and sulfatase 2 (SULF2), play pivotal roles in the post-synthetic modifications of heparan sulfate proteoglycans (HSPGs). Consequently, these extracellular enzymes can regulate a variety of downstream pathways by modulating HSPGs function. During the past decades, researchers have detected the expression of SULF1 and SULF2 in most cancers and revealed their roles in tumor progression and metastasis. Herein we reviewed the metastasis steps which SULFs participated in, elucidated the specific roles and mechanisms of SULFs in metastasis process, and discussed the effects of SULFs in different types of cancers. Moreover, we summarized the role of targeting SULFs in combination therapy to treat metastatic cancers, which provided some novel strategies for cancer therapy.

Nicotinamide N-Methyltransferase: A Promising Biomarker and Target for Human Cancer Therapy

Cancer cells typically exhibit a tightly regulated program of metabolic plasticity and epigenetic remodeling to meet the demand of uncontrolled cell proliferation. The metabolic-epigenetic axis has recently become an increasingly hot topic in carcinogenesis and offers new avenues for innovative and personalized cancer treatment strategies. Nicotinamide N-methyltransferase (NNMT) is a metabolic enzyme involved in controlling methylation potential, impacting DNA and histone epigenetic modification. NNMT overexpression has been described in various solid cancer tissues and even body fluids, including serum, urine, and saliva. Furthermore, accumulating evidence has shown that NNMT knockdown significantly decreases tumorigenesis and chemoresistance capacity. Most importantly, the natural NNMT inhibitor yuanhuadine can reverse epidermal growth factor receptor tyrosine kinase inhibitor resistance in lung cancer cells. In this review, we evaluate the possibility of NNMT as a diagnostic biomarker and molecular target for effective anticancer treatment. We also reveal the exact mechanisms of how NNMT affects epigenetics and the development of more potent and selective inhibitors.

LncRNA AERRIE Is Required for Sulfatase 1 Expression, but Not for Endothelial-to-Mesenchymal Transition

Endothelial cells can acquire a mesenchymal phenotype through a process called Endothelial-to-Mesenchymal transition (EndMT). This event is found in embryonic development, but also in pathological conditions. Blood vessels lose their ability to maintain vascular homeostasis and ultimately develop atherosclerosis, pulmonary hypertension, or fibrosis. An increase in inflammatory signals causes an upregulation of EndMT transcription factors, mesenchymal markers, and a decrease in endothelial markers. In our study, we show that the induction of EndMT results in an increase in long non-coding RNA AERRIE expression. JMJD2B, a known EndMT regulator, induces AERRIE and subsequently SULF1. Silencing of AERRIE shows a partial regulation of SULF1 but showed no effect on the endothelial and mesenchymal markers. Additionally, the overexpression of AERRIE results in no significant changes in EndMT markers, suggesting that AERRIE is marginally regulating mesenchymal markers and transcription factors. This study identifies AERRIE as a novel factor in EndMT, but its mechanism of action still needs to be elucidated.

Targeting molecular signal transduction pathways in hepatocellular carcinoma and its implications for cancer therapy

Hepatocellular carcinoma is a substantial health concern. It is currently the third dominating cause of mortality associated with cancer worldwide. The development of hepatocellular carcinoma is an intricate process that encompasses the impairment of genetic, epigenetic, and signal transduction mechanisms contributing to an aberrant metabolic system, enabling tumorigenesis. Throughout the past decade, research has led to the revelation of molecular pathways implicated in the progression of this notorious disorder. The altered signal transduction pathways, such as the mitogen-activated protein kinase pathway, phosphoinositol 3-kinase/protein kinase B/mammalian target of rapamycin pathway, WNT/β-catenin pathway, hepatocyte growth factor/c-MET pathway, and just another kinase/signal transducers and activators of transcription signaling pathway is of much therapeutic significance, as targeting them may avail to revert, retard or avert hepatocarcinogenesis. The present review article sums up the contemporary knowledge of such signaling mechanisms, including their therapeutic targets and betokens that novel and efficacious therapies can be developed only by the keen understanding of their character in hepatocarcinogenesis. In additament, we address the role of consequential therapeutic agents and preclinical nondrug therapies known for combating hepatocarcinogenesis.

Platycodin D reverses histone deacetylase inhibitor resistance in hepatocellular carcinoma cells by repressing ERK1/2-mediated cofilin-1 phosphorylation

BACKGROUND

Chemoresistance remains the main obstacle in hepatocellular carcinoma (HCC) therapy. Despite significant advances in HCC therapy, HCC still has a poor prognosis. Thus, there is an urgent need to identify a treatment target to reverse HCC chemotherapy resistance. Platycodon grandiflorus (PG) is a perennial herb that has been used as food and traditional Chinese medicine for thousands of years in Northeast Asia. Platycodin D (PD), a main active triterpenoid saponin found in the root of PG, has been reported to possess anticancer properties in several cancer cell lines, including HCC; however, the reversal effect of this molecule on HCC chemoresistance remains largely unknown.

PURPOSE

This study aimed to investigate the role and the mechanism of PD-mediated reversal of the histone deacetylase inhibitor (HDACi) resistance in HCC cells.

METHODS

Human HCC cells (HA22T) and HDACi-resistant (HDACi-R) cells were used. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Combination index was used to calculate the synergism potential. Expression of ERK1/2 (total/phospho), cofilin-1 (total/phospho) and apoptosis-related protein was determined using western blotting. Mitochondrial membrane potential was assessed using the JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide) probe. Apoptosis was detected using the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Mitochondrial reactive oxygen species generation was measured using the MitoSOX Red fluorescent probe.

RESULTS

We found that PD treatment inhibited cell viability both in HA22T HCC and HDACi-R cells. Inhibition of ERK1/2 by PD98059 could reverse drug resistance in HDACi-R cells treated with PD98059 and PD. Nevertheless, pre-treatment with U46619, an ERK1/2 activator, rescued PD-induced apoptosis by decreasing levels of apoptosis-related proteins in HCC cells. The combined treatment of PD with apicidin a powerful HDACi, dramatically enhanced the apoptotic effect in HDACi-R cells.

CONCLUSION

For the first time, we showed that PD reversed HDACi resistance in HCC by repressing ERK1/2-mediated cofilin-1 phosphorylation. Thus, PD can potentially be a treatment target to reverse HCC chemotherapy resistance in future therapeutic trials.

Calmodulin/CaMKII-γ mediates prosurvival capability in apicidin-persistent hepatocellular carcinoma cells via ERK1/2/CREB/c-fos signaling pathway

Calmodulin (CaM), a Ca²⁺ binding protein, plays a critical role in cancer initiation and progression through binding and activating numerous target proteins, including Ca²⁺ /calmodulin-dependent protein kinase (CaMK) family proteins. However, the mechanisms underlying the effects of CaM/CaMKs on the survival capability of liver cancer cells is unclear, and this study investigates this mechanism in apicidin-persistent HA22T cells. CaM level was upregulated, especially in the cytosol, in apicidin-persistent HA22T cells than in parental HA22T cells and was positively associated with cell proliferation and migration capacity of apicidin-persistent HA22T cells. Further, the expression of CaM-activated CaMKs-dependent signaling cascades, including CaMKK2, CaMKIV, CaMKII-γ, and p-CaMKII was observed in apicidin-persistent HA22T cells, which were transiently activated by mitogen-activated protein kinase oncogenic signaling, such as CREB, ERK1/2, and c-fos. Furthermore, a specific CaM inhibitor trifluoperazine reduced the levels of p-CREB, p-ERK1/2, and c-fos in apicidin-persistent HA22T cells than in parental HA22T cells. Additionally, inhibition of CaM also suppressed CaM-induced Bcl-XL (an antiapoptotic protein) expression in apicidin-persistent HA22T cells. Our finding emphasizes an essential role of CaM/CaMKs in augmentation of the survival capability of apicidin-persistent liver cancer cells and suggests that CaM inhibition significantly attenuates CaM-induced tumor growth and abrogates antiapoptotic function and also offers a promising therapeutic target for cancer treatment.

Parameritannin A-2 from Urceola huaitingii enhances doxorubicin-induced mitochondria-dependent apoptosis by inhibiting the PI3K/Akt, ERK1/2 and p38 pathways in gastric cancer cells

Parameritannin A-2 (PA-2) is a natural product extracted from the stems of the plant Urceola huaitingii. Our previous studies have shown that PA-2 exhibits significant synergistic anticancer effects with doxorubicin (DOX) in HGC27 gastric cancer cell lines. Here we report that our isobolographic analysis confirms the synergistic cytotoxic effects of PA-2 and DOX in HGC27 cells. Flow cytometry and immunoblotting indicate that PA-2 enhances DOX-mediated apoptosis. Importantly, PA-2 enhances the intracellular accumulation of DOX in HGC27 cells. The combination of DOX and PA-2 remarkably increases the release of cytochrome C and the activation of caspase-3 and caspase-9, compared with DOX treatment alone. Moreover, PA-2 attenuates the DOX-induced activation of Akt, ERK1/2 and p38 signaling pathways, providing a molecular mechanism for the synergistic effects of DOX and PA-2 in the induction of apoptosis. In conclusion, our studies demonstrate that PA-2 and DOX synergistically induce mitochondria-dependent apoptosis as PA-2 inhibits the PI3K/Akt, ERK1/2 and p38 pathways in HGC27 cells. These findings suggest that the combination treatment with PA-2 and DOX may represent a potent therapy for gastric cancer.

Cryptotanshinone (Dsh-003) from Salvia miltiorrhiza Bunge inhibits prostaglandin E2-induced survival and invasion effects in HA22T hepatocellular carcinoma cells

Human hepatocellular carcinoma (HCC) is currently the second most common cancer and one of the leading causes of cancer-related mortality in Taiwan. Previous reports show that the expression of (E-type prostaglandin 2) EP2 and (E-type prostaglandin 4) EP4 are elevated in HCC and further demonstrate that Prostaglandin E2 (PGE2) induces HA22T cell proliferation and metastasis through EP2 and EP4 receptor. Danshen (root of Salvia miltiorrhiza Bunge) is a very important and popular traditional Chinese herbal medicine which is widely and successfully used against breast cancer, leukemia, pancreatic cancer, and head and neck squamous carcinoma cells. In this study, we used Cryptotansinone (Dsh-003) (MW 269.14) from Danshen to investigate their effect and corresponding mechanism of action in PGE2-treated HA22T cells. Dsh-003 inhibited HA22T cell viability and further induced cell apoptosis in PGE2-treated HA22T cells. Furthermore, Dsh-003 inhibited EP2, EP4, and their downstream effector such as p-PI3K and p-Akt expression in HA22T hepatocellular carcinoma cells. We also observed that Dsh-003 blocked PGE2-induced cell migration by down-regulating PGE2-induced β-catenin expression and by up-regulating E-cadherin and GSK3-β expression. All these findings suggest that Dsh-003 inhibit human HCC cell lines and could potentially be used as a novel drug for HCC treatment.

HDAC inhibitor apicidin suppresses murine oral squamous cell carcinoma cell growth in vitro and in vivo via inhibiting HDAC8 expression

Apicidin, a cyclic peptide histone deacetylase (HDAC) inhibitor, has been demonstrated to exhibit antitumor activity in a number of human cancer types. The present study examined the antitumor activity of apicidin in murine oral squamous cell carcinoma (OSCC) cells. Inhibition of cell proliferation and the expression of selective HDACs were determined in apicidin-treated AT-84 murine OSCC cells. A C3H mouse model with subcutaneous injection of AT-84 cells was used to assess the in vivo effect of apicidin on tumor growth. Apicidin-induced cell growth inhibition and selectively reduced HDAC8 expression in AT-84 cells. Induction of apoptosis and autophagy was observed in apicidin-treated AT-84 cells. Apicidin notably inhibited tumor growth by up to 46% relative to the control group at the end of a 14-day period in a murine tumor model. The immunohistochemistry results in tumor tissues indicated that apicidin inhibited cell proliferation and induced apoptosis and autophagy in AT-84 cell-derived tumor tissues. Overexpression of HDAC8 was observed in the nucleus and cytoplasm in tumor tissues and apicidin significantly inhibited the level of HDAC8 expression, compared with the vehicle group. These results indicated that apicidin inhibited cell proliferation through HDAC8 inhibition in murine OSCC cells in vitro and in vivo. The present study indicated that apicidin may be an effective therapeutic agent for OSCC.

Sulfatase-1 overexpression indicates poor prognosis in urothelial carcinoma of the urinary bladder and upper tract

Urothelial carcinoma (UC), arising from the urothelium of the urinary tract, can occur in the upper (UTUC) and the urinary bladder (UBUC). A representative molecular aberration for UC characteristics and prognosis remains unclear. Data mining of Gene Expression Omnibus focusing on UBUC, we identified sulfatase-1 (SULF1) upregulation is associated with UC progression. SULF1 controls the sulfation status of heparan sulfate proteoglycans and plays a role in tumor growth and metastasis, while its role is unexplored in UC. To first elucidate the clinical significance of SULF1 transcript expression, real-time quantitative RT-PCR was performed in a pilot study of 24 UTUC and 24 UBUC fresh samples. We identified that increased SULF1 transcript abundance was associated with higher primary tumor (pT) status. By testing SULF1 immunoexpression in independent UTUC and UBUC cohorts consisted of 340 and 295 cases, respectively, high SULF1 expression was significantly associated with advanced pT and nodal status, higher histological grade and presence of vascular invasion in both UTUC and UBUC. In multivariate survival analyses, high SULF1 expression was independently associated with worse DSS (UTUC hazard ratio [HR] = 3.574, P < 0.001; UBUC HR = 2.523, P = 0.011) and MeFS (UTUC HR = 3.233, P < 0.001; UBUC HR = 1.851, P = 0.021). Furthermore, depletion of SULF1 expression by using RNA interference leaded to impaired cell proliferative, migratory, and invasive abilities in vitro. In addition, we further confirmed oncogenic role of SULF1 with gain-of function experiments. In conclusion, our findings implicate the oncogenic role of SULF1 expression in UC, suggesting SULF1 as a prognostic and therapeutic target of UC.

Modification of Epigenetic Histone Acetylation in Hepatocellular Carcinoma

Cells respond to various environmental factors such as nutrients, food intake, and drugs or toxins by undergoing dynamic epigenetic changes. An imbalance in dynamic epigenetic changes is one of the major causes of disease, oncogenic activities, and immunosuppressive effects. The aryl hydrocarbon receptor (AHR) is a unique cellular chemical sensor present in most organs, and its dysregulation has been demonstrated in multiple stages of tumor progression in humans and experimental models; however, the effects of the pathogenic mechanisms of AHR on epigenetic regulation remain unclear. Apart from proto-oncogene activation, epigenetic repressions of tumor suppressor genes are involved in tumor initiation, procession, and metastasis. Reverse epigenetic repression of the tumor suppressor genes by epigenetic enzyme activity inhibition and epigenetic enzyme level manipulation is a potential path for tumor therapy. Current evidence and our recent work on deacetylation of histones on tumor-suppressive genes suggest that histone deacetylase (HDAC) is involved in tumor formation and progression, and treating hepatocellular carcinoma with HDAC inhibitors can, at least partially, repress tumor proliferation and transformation by recusing the expression of tumor-suppressive genes such as TP53 and RB1.

Paper-based microreactor array for rapid screening of cell signaling cascades

Investigation of cell signaling pathways is important for the study of pathogenesis of cancer. However, the related operations used in these studies are time consuming and labor intensive. Thus, the development of effective therapeutic strategies may be hampered. In this work, gel-free cell culture and subsequent immunoassay has been successfully integrated and conducted in a paper-based microreactor array. Study of the activation level of different kinases of cells stimulated by different conditions, i.e., IL-6 stimulation, starvation, and hypoxia, was demonstrated. Moreover, rapid screening of cell signaling cascades after the stimulations of HGF, doxorubicin, and UVB irradiation was respectively conducted to simultaneously screen 40 kinases and transcription factors. Activation of multi-signaling pathways could be identified and the correlation between signaling pathways was discussed to provide further information to investigate the entire signaling network. The present technique integrates most of the tedious operations using a single paper substrate, reduces sample and reagent consumption, and shortens the time required by the entire process. Therefore, it provides a first-tier rapid screening tool for the study of complicated signaling cascades. It is expected that the technique can be developed for routine protocol in conventional biological research laboratories.

PI3K/Akt/mTOR and Ras/Raf/MEK/ERK signaling pathways inhibitors as anticancer agents: Structural and pharmacological perspectives

The protein kinases regulate cellular functions such as transcription, translation, proliferation, growth and survival by the process of phosphorylation. Over activation of signaling pathways play a major role in oncogenesis. The PI3K signaling pathway is dysregulated almost in all cancers due to the amplification, genetic mutation of PI3K gene and the components of the PI3K pathway themselves. Stimulation of the PI3K/Akt/mTOR and Ras/Raf/MEK/ERK pathways enhances growth, survival, and metabolism of cancer cells. Recently, the PI3K/Akt/mTOR and Ras/Raf/MEK/ERK signaling pathways have been identified as promising therapeutic targets for cancer therapy. The kinase inhibitors with enhanced specificity and improved pharmacokinetics have been considered for design and development of anticancer agents. This review focuses primarily on the Ras/Raf/MEK/ERK and PI3K/Akt/mTOR signaling pathways as therapeutic targets of anticancer drugs, their specific and dual inhibitors, structure activity relationships (SARs) and inhibitors under clinical trials.

Phosphatidylinositol- 3-kinase inhibitor induces chemosensitivity to a novel derivative of doxorubicin, AD198 chemotherapy in human bladder cancer cells in vitro

BACKGROUND

Doxorubicin (Dox) is widely used to treat progressed bladder cancer after transurethral resection. The use of Dox-chemotherapy has been limited due to induced drug resistance and cumulative cardiotoxic effects. N-benzyladriamycin-14-valerate (AD198), a novel derivative of Dox, has a potential to become a more effective treatment than Dox by overcoming drug resistance and cardio-toxicity as shown in the rodent model of lymphoma in vivo. The purpose of this study was to compare the efficacy of Dox and AD198 and explore their mechanisms in inhibition on human bladder cancer cells in vitro.

METHODS

We evaluated the effects of Dox and AD198 on cell viability of human transitional cell carcinoma (TCC) cell lines T24 and UMUC3 by MTS assay in vitro. The effects of Dox and AD198 on cell apoptosis were determined by caspase 3/7 assay, generation of reactive oxygen species (ROS), and Western Blotting (WB) analysis.

RESULTS

AD198 was more effective than Dox in inhibition of cell viability of T24 and UMUC3 cells in vitro. Both Dox and AD198 significantly increased the generation of ROS and induced apoptosis in caspase-dependent and -independent manner in T24 and UMUC3 cells. AD 198 induced significantly higher production of ROS as compared to Dox in human TCC cells. Dox and AD198 activated the pro-apoptotic p38 MAPK pathway; however, on the other hand also increased phosphorylation of AKT, an anti-apoptotic signaling pathway, in T24 and UMUC3 cells. Combined treatment of PI3K inhibitor (LY294002) with Dox or AD198 inhibited cell viability of T24 and UMUC3 cells more effectively than any of drug treatments alone.

CONCLUSIONS

These data suggest that AD198 as novel derivative of Dox, could be a used as effective treatment for bladder cancer. Dox and AD198 induced PI3K/AKT signaling pathway that is a one of the indicators of pro-survival and possible drug-resistance mechanisms of chemotherapies in bladder cancer. Combined therapies of Dox or AD198 with inhibitors of PI3K/AKT signaling pathway might lead to more effective treatment outcome for patients diagnosed with bladder cancer based on our in vitro experiments.

Restoration of epigenetically silenced SULF1 expression by 5-aza-2-deoxycytidine sensitizes hepatocellular carcinoma cells to chemotherapy-induced apoptosis

Background

Hepatocellular carcinoma (HCC) is the second most frequent cause of cancer death worldwide. Sulfatase 1 (SULF1) functions as a tumor suppressor in HCC cell lines in vitro but also has an oncogenic effect in some HCCs in vivo.

Aim

The purpose of this study was to examine the mechanisms regulating SULF1 and its function in HCC.

Methods

First, SULF1 mRNA and protein expression were examined. Second, we examined SULF1 gene copy numbers in HCC cells. Third, we assessed whether DNA methylation or methylation and/or acetylation of histone marks on the promoter regulate SULF1 expression. Finally, we examined the effect of 5-aza-2′-deoxycytidine (5-Aza-dC) on sulfatase activity and drug-induced apoptosis.

Results

SULF1 mRNA was downregulated in nine of eleven HCC cell lines, but only in six of ten primary tumors. SULF1 mRNA correlated with protein expression. Gene copy number assessment by fluorescence in situ hybridization showed intact SULF1 alleles in low-SULF1-expressing cell lines. CpG island methylation in the SULF1 promoter and two downstream CpG islands did not show an inverse correlation between DNA methylation and SULF1 expression. However, chromatin immunoprecipitation showed that the SULF1 promoter acquires a silenced chromatin state in low-SULF1-expressing cells through an increase in di/trimethyl-K9H3 and trimethyl-K27H3 and a concomitant loss of activating acetyl K9, K14H3 marks. 5-Aza-dC restored SULF1 mRNA expression in SULF1-negative cell lines, with an associated increase in sulfatase activity and sensitization of HCC cells to cisplatin-induced apoptosis.

Conclusion

SULF1 gene silencing in HCC occurs through histone modifications on the SULF1 promoter. Restoration of SULF1 mRNA expression by 5-Aza-dC sensitized HCC cells to drug-induced apoptosis.

Activation of the transforming growth factor-β/SMAD transcriptional pathway underlies a novel tumor-promoting role of sulfatase 1 in hepatocellular carcinoma

In vitro studies have proposed a tumor suppressor role for sulfatase 1 (SULF1) in hepatocellular carcinoma (HCC); however, high expression in human HCC has been associated with poor prognosis. The reason underlying this paradoxical observation remains to be explored. Using a transgenic (Tg) mouse model overexpressing Sulf1 (Sulf1-Tg), we assessed the effects of SULF1 on the diethylnitrosamine model of liver carcinogenesis. Sulf1-Tg mice show a higher incidence of large and multifocal tumors with diethylnitrosamine injection compared to wild-type mice. Lung metastases were found in 75% of Sulf1-Tg mice but not in wild-type mice. Immunohistochemistry, immunoblotting, and reporter assays all show a significant activation of the transforming growth factor-β (TGF-β)/SMAD transcriptional pathway by SULF1 both in vitro and in vivo. This effect of SULF1 on the TGF-β/SMAD pathway is functional; overexpression of SULF1 promotes TGF-β-induced gene expression and epithelial-mesenchymal transition and enhances cell migration/invasiveness. Mechanistic analyses demonstrate that inactivating mutation of the catalytic site of SULF1 impairs the above actions of SULF1 and diminishes the release of TGF-β from the cell surface. We also show that SULF1 expression decreases the interaction between TGF-β1 and its heparan sulfate proteoglycan sequestration receptor, TGFβR3. Finally, using gene expression from human HCCs, we show that patients with high SULF1 expression have poorer recurrence-free survival (hazard ratio 4.1, 95% confidence interval 1.9-8.3; P = 0.002) compared to patients with low SULF1. We also found strong correlations of SULF1 expression with TGF-β expression and with several TGF-β-related epithelial-mesenchymal transition genes in human HCC.

CONCLUSION

Our study proposes a novel role of SULF1 in HCC tumor progression through augmentation of the TGF-β pathway, thus defining SULF1 as a potential biomarker for tumor progression and a novel target for drug development for HCC.

Post-Synthetic Regulation of HS Structure: The Yin and Yang of the Sulfs in Cancer

Heparan sulfate (HS) is a complex polysaccharide that takes part in most major cellular processes, through its ability to bind and modulate a very large array of proteins. These interactions involve saccharide domains of specific sulfation pattern (S-domains), the assembly of which is tightly orchestrated by a highly regulated biosynthesis machinery. Another level of structural control does also take place at the cell surface, where degrading enzymes further modify HS post-synthetically. Amongst them are the Sulfs, a family of extracellular sulfatases (two isoforms in human) that catalyze the specific 6-O-desulfation of HS. By targeting HS functional sulfated domains, Sulfs dramatically alter its ligand binding properties, thereby modulating a broad range of signaling pathways. Consequently, Sulfs play major roles during development, as well as in tissue homeostasis and repair. Sulfs have also been associated with many pathologies including cancer, but despite increasing interest, the role of Sulfs in tumor development still remains unclear. Studies have been hindered by a poor understanding of the Sulf enzymatic activities and conflicting data have shown either anti-oncogenic or tumor-promoting effects of these enzymes, depending on the tumor models analyzed. These opposite effects clearly illustrate the fine tuning of HS functions by the Sulfs, and the need to clarify the mechanisms involved. In this review, we will detail the present knowledge on the structural and functional properties of the Sulfs, with a special focus on their implication during tumor progression. Finally, we will discuss attempts and perspectives of using the Sulfs as a biomarker of cancer prognosis and diagnostic and as a target for anti-cancer therapies.

Apicidin-resistant HA22T hepatocellular carcinoma cells massively promote pro-survival capability via IGF-IR/PI3K/Akt signaling pathway activation

Despite rapid advances in the diagnostic and surgical procedures, hepatocellular carcinoma (HCC) remains one of the most difficult human malignancies to treat. This may be due to the chemoresistant behaviors of HCC. It is believed that acquired resistance could be overcome and improve the overall survival of HCC patients by understanding the mechanisms of chemoresistance in HCC. A stable HA22T cancer line, which is chronically resistant to a histone deacetylase inhibitor, was established. After comparing the molecular mechanism of apicidin-R HA22T cells to parental ones by Western blotting, cell cycle-regulated proteins did not change in apicidin-R cells, but apicidin-R cells were more proliferative and had higher tumor growth (wound-healing assay and nude mice xenograft model). Moreover, apicidin-R cells displayed increased levels of p-IGF-IR, p-PI3K, p-Akt, Bcl-xL, and Bcl-2 but also significantly inhibited the tumor suppressor PTEN protein and apoptotic pathways when compared to the parental strain. Therefore, the highly proliferative effect of apicidin-R HA22T cells was blocked by Akt knockdown. For all these findings, we believe that novel strategies to attenuate IGF-IR/PI3K/Akt signaling could overcome chemoresistance toward the improvement of overall survival of HCC patients.

Human sulfatase-1 inhibits the migration and proliferation of SMMC-7721 hepatocellular carcinoma cells by downregulating the growth factor signaling

AIM

  The human sulfatase-1 (hSulf-1) gene regulates the sulfation of heparan sulfate proteoglycans (HSPG) and suppresses tumorigenesis and angiogenesis by inhibiting several growth factor signaling pathways. Because the serine-threonine protein kinase (AKT) and extracellular signal-regulated kinase (ERK) signaling pathways are critical in cell survival, proliferation, migration and angiogenesis, the possible correlation between hSulf-1 and AKT/ERK signaling in hepatocellular carcinoma (HCC) cells needs further exploration.

METHODS

  Adenovirus Ad5-hSulf1 carrying the hSulf-1 gene, and vectors carrying hSulf-1 shRNA, AKT shRNA and ERK shRNA were constructed and used to manipulate the expression of hSulf-1, AKT and ERK in SMMC-7721 cells. The scarification test, transwell and 3-(4 5-dimethylthiazol-2-yl)-2 5-diphenyltetrazolium bromide assays were used to examine the cellular migration and proliferation, and the expression of hSulf-1 and signaling factors, including the total and phosphorylated AKT and ERK, was analyzed by western blot in SMMC-7721 cells.

RESULTS

  After infection with Ad5-hSulf1, the expression of hSulf-1 was increased with viral multiplicity of infection in SMMC-7721 cells. Compared with the control adenovirus Ad5-EGFP and blank control groups, cells in the Ad5-hSulf1 group were showed that the phosphorylation of AKT and ERK was decreased. Meanwhile, the cell migration and cell viability were obviously suppressed.

CONCLUSION

  The expression of hSulf-1 mediated by adenovirus in HCC cells could downregulate the activity of AKT and ERK signaling pathways, and inhibit HCC cell migration and proliferation. The hSulf-1 gene may be considered as a candidate of antitumor factor for cancer gene therapy.

Apicidin and docetaxel combination treatment drives CTCFL expression and HMGB1 release acting as potential antitumor immune response inducers in metastatic breast cancer cells

Currently approved combination regimens available for the treatment of metastatic tumors, such as breast cancer, have been shown to increase response rates, often at the cost of a substantial increase in toxicity. An ideal combination strategy may consist of agents with different mechanisms of action leading to complementary antitumor activities and safety profiles. In the present study, we investigated the effects of the epigenetic modulator apicidin in combination with the cytotoxic agent docetaxel in tumor breast cell lines characterized by different grades of invasiveness. We report that combined treatment of apicidin and docetaxel, at low toxicity doses, stimulates in metastatic breast cancer cells the expression of CTCF-like protein and other cancer antigens, thus potentially favoring an antitumor immune response. In addition, apicidin and docetaxel co-treatment specifically stimulates apoptosis, characterized by an increased Bax/Bcl-2 ratio and caspase-8 activation. Importantly, following combined exposure to these agents, metastatic cells were also found to induce signals of immunogenic apoptosis such as cell surface expression of calreticulin and release of considerable amounts of high-mobility group box 1 protein, thus potentially promoting the translation of induced cell death into antitumor immune response. Altogether, our results indicate that the combined use of apicidin and docetaxel, at a low toxicity profile, may represent a potential innovative strategy able to activate complementary antitumor pathways in metastatic breast cancer cells, associated with a potential control of metastatic growth and possible induction of antitumor immunity.

Diacylglycerol kinase alpha enhances hepatocellular carcinoma progression by activation of Ras-Raf-MEK-ERK pathway

BACKGROUND & AIMS

Diacylglycerol kinases (DGKs) were recently recognized as key regulators in cell signaling pathways. We investigated whether DGKα is involved in human hepatocellular carcinoma (HCC) progression.

METHODS

We silenced or overexpressed DGKα in HCC cells and assessed its effect on tumor progression. DGKα expression in 95 surgical samples was analyzed by immunohistochemistry, and the expression status of each sample was correlated with clinicopathological features.

RESULTS

DGKα was detected in various HCC cell lines but at very low levels in the normal liver. Knockdown of DGKα significantly suppressed cell proliferation and invasion. Overexpression of wild type (WT) DGKα, but not its kinase-dead (KD) mutant, significantly enhanced cell proliferation. DGKα knockdown impaired MEK and ERK phosphorylation, but did not inhibit Ras activation in HCC cells. In a xenograft model, WT DGKα overexpression significantly enhanced tumor growth compared to the control, but KD DGKα mutant had no effect. Immunohistochemical studies showed that DGKα was expressed in cancerous tissue, but not in adjacent non-cancerous hepatocytes. High DGKα expression (≥20%) was associated with high Ki67 expression (p<0.05) and a high rate of HCC recurrence (p=0.033) following surgery. In multivariate analyses, high DGKα expression was an independent factor for determining HCC recurrence after surgery.

CONCLUSIONS

DGKα is involved in HCC progression by activation of the MAPK pathway. DGKα could be a novel target for HCC therapeutics as well as a prognostic marker.

HSulf-1 suppresses cell growth and down-regulates Hedgehog signaling in human gastric cancer cells

Gastric cancer is the second most lethal cancer worldwide. Despite the current surgical and adjuvant therapies, 5-year survival remains less than 20-25% in the US, Europe and China. Therefore, there is an urgent need to identify new therapeutic targets for treating this malignant disease. Accumulating evidence has supported that aberrant activation of the Hedgehog signaling pathway plays a crucial role in tumorigenesis and progression of gastric cancer. Human sulfatase-1 (HSulf-1) is a recently identified enzyme that desulfates cell surface heparan sulfate proteoglycans (HSPGs), which is critical for Hedgehog signal transduction under a highly sulfated state. HSulf-1 has recently emerged as a tumor suppressor gene in certain types of cancer, including ovarian, breast, myeloma and hepatocellular carcinoma; however, its role in gastric cancer remains to be elucidated. Therefore, we established HSulf-1-expressing monoclonal MKN28 gastric cancer cells to investigate its function in gastric cancer. Expression of HSulf-1 significantly suppressed cellular proliferation and growth in MKN28 gastric cancer cells. Notably, HSulf-1 inhibits Gli-mediated transcription and down-regulates the expression of Hedgehog target genes, including GLI1, PTCH1/2, HHIP, CCND1, C-MYC and BCL-2. Collectively, the study provides evidence that HSulf-1 may function as a tumor suppressor in gastric cancer. It suppresses gastric cancer cell proliferation, possibly through abrogating the Hedgehog signaling pathway. The study provides new mechanistic insight into HSulf-1- mediated tumor suppression, and supports the use of HSulf-1 as a potential new therapeutic target in treating gastric cancer.

SULFs in human neoplasia: implication as progression and prognosis factors

Background

The sulfation pattern of heparan sulfate chains influences signaling events mediated by heparan sulfate proteoglycans located on cell surface. SULF1 and SULF2 are two endosulfatases able to cleave specific 6-O sulfate groups within the heparan chains. Their action can modulate signaling processes, many of which with key relevance for cancer development and expansion. SULF1 has been associated with tumor suppressor effects in various models of cancer, whereas SULF2 dysregulation was in relation with protumorigenic actions. However, other observations argue for contradictory effects of these sulfatases in cancer, suggesting the complexity of their action in the tumor microenvironment.

Methods

We compared the expression of the genes encoding SULF1, SULF2 and heparan sulfate proteoglycans in a large panel of cancer samples to their normal tissue counterparts using publicly available gene expression data, including the data obtained from two cohorts of newly-diagnosed multiple myeloma patients, the Oncomine Cancer Microarray database, the Amazonia data base and the ITTACA database. We also analysed prognosis data in relation with these databases.

Results

We demonstrated that SULF2 expression in primary multiple myeloma cells was associated with a poor prognosis in two independent large cohorts of patients. It remained an independent predictor when considered together with conventional multiple myeloma prognosis factors. Besides, we observed an over-representation of SULF2 gene expression in skin cancer, colorectal carcinoma, testicular teratoma and liver cancer compared to their normal tissue counterpart. We found that SULF2 was significantly over-expressed in high grade uveal melanoma compared to low grade and in patients presenting colorectal carcinoma compared to benign colon adenoma.

We observed that, in addition to previous observations, SULF1 gene expression was increased in T prolymphocytic leukemia, acute myeloid leukemia and in renal carcinoma compared to corresponding normal tissues. Furthermore, we found that high SULF1 expression was associated with a poor prognosis in lung adenocarcinoma.

Finally, SULF1 and SULF2 were simultaneously overexpressed in 6 cancer types: brain, breast, head and neck, renal, skin and testicular cancers.

Conclusions

SULF1 and SULF2 are overexpressed in various human cancer types and can be associated to progression and prognosis. Targeting SULF1 and/or SULF2 could be interesting strategies to develop novel cancer therapies.

Sulfatase 2 protects hepatocellular carcinoma cells against apoptosis induced by the PI3K inhibitor LY294002 and ERK and JNK kinase inhibitors

BACKGROUND

Sulfatase 2 (SULF2), an extracellular heparan sulphate 6-O-endosulphatase, has an oncogenic effect in hepatocellular carcinoma (HCC) that is partially mediated through glypican 3, which promotes heparin-binding growth factor signalling and HCC cell growth. SULF2 also increases phosphorylation of the anti-apoptotic Akt kinase substrate GSK3β and SULF2 expression is associated with a decreased apoptotic index in human HCCs.

METHODS

We investigated the functional and mechanistic effects of SULF2 on drug-induced apoptosis of HCC cells using immunohistochemistry, Western immunoblotting, gene transfection, real-time quantitative polymerase chain reaction, MTT and apoptosis assays and immunocytochemistry.

RESULTS

The increased expression of SULF2 in human HCCs was confirmed by immunohistochemistry and immunoblotting. Treatment with inhibitors of MEK, JNK and PI3 kinases decreased the viability of SULF2-negative Hep3B HCC cells and induced apoptotic caspase 3 and 7 activity, which was most strongly induced by the PI3K inhibitor LY294002. Forced expression of SULF2 in Hep3B cells significantly decreased activity of the apoptotic caspases 3 and 7 and induced resistance to LY294002-induced apoptosis. As expected, LY294002 inhibited activation of Akt kinase by PI3K. Conversely, knockdown of SULF2 using an shRNA construct targeting the SULF2 mRNA induced profound cell growth arrest and sensitized the endogenously SULF2-expressing HCC cell lines Huh7 and SNU182 to drug-induced apoptosis. The effects of knockdown of SULF2 on HCC cells were mediated by decreased Akt phosphorylation, downregulation of cyclin D1 and the anti-apoptotic molecule Bcl-2, and upregulation of the pro-apoptotic molecule BAD.

CONCLUSION

The prosurvival, anti-apoptotic effect of SULF2 in HCC is mediated through activation of the PI3K/Akt pathway.

Involvement of miR-199a downregulation in the preventive effects of Jianpi Jiedu Recipe against experimental hepatocarcinoma in rats

AIM: To investigate the preventive effects of Jianpi Jiedu Recipe against diethylnitrosamine-induced hepatocarcinoma in rats and explore the involvement of miR-199a downregulation in this process.

METHODS: Male Wistar rats were randomly divided into three groups: normal control group (n = 25), model group (n = 40 ) and prevention group (n = 40). The normal control group was given normal saline [10 mL/(kg•d) ig] for 12 weeks, the model group was given diethylnitrosamine dissolved in drinking water (80 ppm) at a dose of 8 mg/(kg•d) for the same duration, and the prevention group was given both diethylnitrosamine at the same dose and Jianpi Jiedu Recipe [17.5 g/(kg•d), ig] for the same duration. Five rats in each group were executed at weeks 4, 8, 12 and 16, respectively, and the remaining rats were killed at week 20. Meanwhile, the mortality, incidence of ascites, and liver and spleen index were measured. Hematoxylin-eosin staining (HE) was used to examine hepatic pathological changes. The expression of miR-199a mRNA was detected by real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: At week 20, the mortality rate and the incidence rate of ascites were 0% and 0% in the normal control group, 42.5% and 87.5% in the model group, and 17.5% and 44.4% in the prevention group, respectively. The mortality rate and the incidence of ascites were significantly lower in the prevention group than in the model group (both P < 0.05). At week 16, the incidence of HCC was 100% in both the model group and prevention group and 0% in the normal control group, the incidence of grade III liver cancer was 100% (5/5) in the model group, and the incidences of grade I, II and III liver cancer were 40% (2/5), 40% (2/5 ) and 20% (1/5) in the prevention group, respectively. Compared with the model group, the liver and spleen index in the prevention group were significantly reduced at all time points (all P < 0.01). Real-time RT-PCR results showed that the expression of miR-199a was significantly upregulated in the model group. However, miR-199a expression was significantly downregulated in the prevention group at all time points except at week 16 (all P < 0.01).

CONCLUSION: Jianpi Jiedu Recipe has good preventive effects against hepatocarcinoma in rats perhaps partly by downregulating miR-199a expression.

The tumor suppressor function of human sulfatase 1 (SULF1) in carcinogenesis

INTRODUCTION

Human sulfatase 1 (SULF1) was recently identified and shown to desulfate cellular heparan sulfate proteoglycans (HSPGs). Since sulfated HSPGs serve as co-receptors for many growth factors and cytokines, SULF1 was predicted to modulate growth factor and cytokine signaling.

DISCUSSION

The role of SULF1 in growth factor signaling and its effects on human tumorigenesis are under active investigation. Initial results show that SULF1 inhibits the co-receptor function of HSPGs in multiple receptor tyrosine kinase signaling pathways, particularly by the heparin binding growth factors--fibroblast growth factor 2, vascular endothelial growth factor, hepatocyte growth factor, PDGF, and heparin-binding epidermal growth factor (HB-EGF). SULF1 is downregulated in the majority of cancer cell lines examined, and forced expression of SULF1 decreases cell proliferation, migration, and invasion. SULF1 also promotes drug-induced apoptosis of cancer cells in vitro and inhibits tumorigenesis and angiogenesis in vivo.

CONCLUSION

Strategies targeting SULF1 or the interaction between SULF1 and the related sulfatase 2 will potentially be important in developing novel cancer therapies.