Downregulation of P-gp, Ras and p-ERK1/2 contributes to the arsenic trioxide-induced reduction in drug resistance towards doxorubicin in gastric cancer cell lines

Research progress on arsenic, arsenic-containing medicinal materials, and arsenic-containing preparations: clinical application, pharmacological effects, and toxicity

Introduction: The toxicity of arsenic is widely recognized globally, mainly harming human health by polluting water, soil, and food. However, its formulations can also be used for the clinical treatment of diseases such as leukemia and tumors. Arsenic has been used as a drug in China for over 2,400 years, with examples such as the arsenic-containing drug realgar mentioned in Shennong's Herbal Classic. We have reviewed references on arsenic over the past thirty years and found that research has mainly focused on clinical, pharmacological, and toxicological aspects. Results and Discussion: The finding showed that in clinical practice, arsenic trioxide is mainly used in combination with all-trans retinoic acid (ATRA) at a dose of 10 mg/d for the treatment of acute promyelocytic leukemia (APL); realgar can be used to treat acute promyelocytic leukemia, myelodysplastic syndrome, and lymphoma. In terms of pharmacology, arsenic mainly exerts anti-tumor effects. The dosage range of the action is 0.01-80 μmol/L, and the concentration of arsenic in most studies does not exceed 20 μmol/L. The pharmacological effects of realgar include antiviral activity, inhibition of overactivated lactate dehydrogenase, and resistance to malaria parasites. In terms of toxicity, arsenic is toxic to multiple systems in a dose-dependent manner. For example, 5 μmol/L sodium arsenite can induce liver oxidative damage and promote the expression of pro-inflammatory factors, and 15 μmol/L sodium arsenite induces myocardial injury; when the concentration is higher, it is more likely to cause toxic damage.

Role of microRNAs in regulation of doxorubicin and paclitaxel responses in lung tumor cells

Lung cancer as the leading cause of cancer related mortality is always one of the main global health challenges. Despite the recent progresses in therapeutic methods, the mortality rate is still significantly high among lung cancer patients. A wide range of therapeutic methods including chemotherapy, radiotherapy, and surgery are used to treat lung cancer. Doxorubicin (DOX) and Paclitaxel (TXL) are widely used as the first-line chemotherapeutic drugs in lung cancer. However, there is a significant high percentage of DOX/TXL resistance in lung cancer patients, which leads to tumor recurrence and metastasis. Considering, the side effects of these drugs in normal tissues, it is required to clarify the molecular mechanisms of DOX/TXL resistance to introduce the efficient prognostic and therapeutic markers in lung cancer. MicroRNAs (miRNAs) have key roles in regulation of different pathophysiological processes including cell division, apoptosis, migration, and drug resistance. MiRNA deregulations are widely associated with chemo resistance in various cancers. Therefore, considering the importance of miRNAs in chemotherapy response, in the present review, we discussed the role of miRNAs in regulation of DOX/TXL response in lung cancer patients. It has been reported that miRNAs mainly induced DOX/TXL sensitivity in lung tumor cells by the regulation of signaling pathways, autophagy, transcription factors, and apoptosis. This review can be an effective step in introducing miRNAs as the non-invasive prognostic markers to predict DOX/TXL response in lung cancer patients.

Interaction Analysis of MRP1 with Anticancer Drugs Used in Ovarian Cancer: In Silico Approach

Multidrug resistance (MDR) is one of the major therapeutic challenges that limits the efficacy of chemotherapeutic response resulting in poor prognosis of ovarian cancer (OC). The multidrug resistance protein 1 (MRP1) is a membrane-bound ABC transporter involved in cross resistance to many structurally and functionally diverse classes of anticancer drugs including doxorubicin, taxane, and platinum. In this study, we utilize homology modelling and molecular docking analysis to determine the binding affinity and the potential interaction sites of MRP1 with Carboplatin, Gemcitabine, Doxorubicin, Paclitaxel, and Topotecan. We used AutoDock Vina scores to compare the binding affinities of the anticancer drugs against MRP1. Our results depicted Carboplatin < Gemcitabine < Topotecan < Doxorubicin < Paclitaxel as the order of binding affinities. Paclitaxel has shown the highest binding affinity whereas Carboplatin displayed the lowest affinity to MRP1. Interestingly, our data showed that Carboplatin, Paclitaxel, and Topotecan bind specifically to Asn510 residue in the transmembrane domains 1 of the MRP1. Our results suggest that Carboplatin could be an appropriate therapeutic choice against MRP1 in OC as it couples weakly with Carboplatin. Further, our findings also recommend opting Carboplatin with Gemcitabine as a combinatorial chemotherapeutic approach to overcome MDR phenotype associated with recurrent OC.

Pharmacokinetic herb-drug interactions between Aidi injection and doxorubicin in rats with diethylnitrosamine-induced hepatocellular carcinoma

BACKGROUND

Aidi Injection (ADI), a Chinese herbal preparation with anti-cancer activity, is used for the treatment of hepatocellular carcinoma (HCC). Several clinical studies have shown that co-administration of ADI with doxorubicin (DOX) is associated with reduced toxicity of chemotherapy, enhanced clinical efficacy and improved quality of life for patients. However, limited information is available about the herb-drug interactions between ADI and DOX. The study aimed to investigate the pharmacokinetic mechanism of herb-drug interactions between ADI and DOX in a rat model of HCC.

METHODS

Experimental HCC was induced in rats by oral administration of diethylnitrosamine. The HCC rats were pretreated with ADI (10 mL/kg, intraperitoneal injection) for 14 consecutive days prior to administration of DOX (7 mg/kg, intravenous injection) to investigate pharmacokinetic interactions. Plasma concentrations of DOX and its major metabolite, doxorubicinol (DOXol), were determined using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

RESULTS

Preadministration of ADI significantly altered the pharmacokinetics of DOX in HCC rats, leading to increased plasma concentrations of both DOX and DOXol. The area under the plasma drug concentration-time curve (AUCs) of DOX and DOXol in rats pretreated with ADI were 3.79-fold and 2.92-fold higher, respectively, than those in control rats that did not receive ADI.

CONCLUSIONS

Increased levels of DOX and DOXol were found in the plasma of HCC rats pretreated with ADI.

Molecular mechanisms of chemo- and radiotherapy resistance and the potential implications for cancer treatment

Cancer is a leading cause of death worldwide. Surgery is the primary treatment approach for cancer, but the survival rate is very low due to the rapid progression of the disease and presence of local and distant metastasis at diagnosis. Adjuvant chemotherapy and radiotherapy are important components of the multidisciplinary approaches for cancer treatment. However, resistance to radiotherapy and chemotherapy may result in treatment failure or even cancer recurrence. Radioresistance in cancer is often caused by the repair response to radiation-induced DNA damage, cell cycle dysregulation, cancer stem cells (CSCs) resilience, and epithelial-mesenchymal transition (EMT). Understanding the molecular alterations that lead to radioresistance may provide new diagnostic markers and therapeutic targets to improve radiotherapy efficacy. Patients who develop resistance to chemotherapy drugs cannot benefit from the cytotoxicity induced by the prescribed drug and will likely have a poor outcome with these treatments. Chemotherapy often shows a low response rate due to various drug resistance mechanisms. This review focuses on the molecular mechanisms of radioresistance and chemoresistance in cancer and discusses recent developments in therapeutic strategies targeting chemoradiotherapy resistance to improve treatment outcomes.

The ATO/miRNA-885-5p/MTPN axis induces reversal of drug-resistance in cholangiocarcinoma

PURPOSE

Cholangiocarcinoma (CCA) is the second most malignant tumor of the hepatobiliary system. Due to its cumbersome early diagnosis and rapid progression, chemotherapy has become the main treatment option. Primary drug resistance is a major cause of the poor efficacy of chemotherapeutic drugs. Therefore, it is considered urgent to explore new drugs to overcome primary drug resistance of CCA.

METHODS

Western blot and qRT-PCR assays were used to assess the expression of myotrophin (MTPN) and microRNA-885-5p (miR-885-5p) in CCA tissues and cells. The viability of CCA cells treated with arsenic trioxide (ATO), 5-fluorouracil (5-Fu) and cisplatin (CDDP) was analyzed using a CCK-8 assay. A luciferase reporter assay was used to assess the interaction between miR-885-5p and MTPN. Kaplan-Meier analyses were used for survival assessments.

RESULT

We found that ATO can reduce the resistance of CCA cells to 5-Fu and CDDP and promote the killing effect of 5-Fu and CDDP. Low-dose ATO showed an anti-drug-resistance effect through up-regulation of the expression of miR-885-5p. Combined with sequencing results and database predictions, we found that MTPN may serve as a direct target of miR-885-5p. After MTPN knockdown, the sensitivity of CCA cells to 5-FU and CDDP was increased. Finally, we found that ATO can reverse chemotherapy resistance induced by overexpression of MTPN.

CONCLUSION

Our data indicate that the ATO/miR-885-5p/MTPN axis may serve as a target for improving the sensitivity of CCA cells to chemotherapy.

Inhibitors of Chemoresistance Pathways in Combination with Ara-C to Overcome Multidrug Resistance in AML. A Mini Review

Acute myeloid leukemia (AML), the most common type of leukemia in older adults, is a heterogeneous disease that originates from the clonal expansion of undifferentiated hematopoietic progenitor cells. These cells present a remarkable variety of genes and proteins with altered expression and function. Despite significant advances in understanding the molecular panorama of AML and the development of therapies that target mutations, survival has not improved significantly, and the therapy standard is still based on highly toxic chemotherapy, which includes cytarabine (Ara-C) and allogeneic hematopoietic cell transplantation. Approximately 60% of AML patients respond favorably to these treatments and go into complete remission; however, most eventually relapse, develop refractory disease or chemoresistance, and do not survive for more than five years. Therefore, drug resistance that initially occurs in leukemic cells (primary resistance) or that develops during or after treatment (acquired resistance) has become the main obstacle to AML treatment. In this work, the main molecules responsible for generating chemoresistance to Ara-C in AML are discussed, as well as some of the newer strategies to overcome it, such as the inclusion of molecules that can induce synergistic cytotoxicity with Ara-C (MNKI-8e, emodin, metformin and niclosamide), subtoxic concentrations of chemotherapy (PD0332991), and potently antineoplastic treatments that do not damage nonmalignant cells (heteronemin or hydroxyurea + azidothymidine).

Lymphatic metastasis-related TBL1XR1 enhances stemness and metastasis in gastric cancer stem-like cells by activating ERK1/2-SOX2 signaling

The poor prognosis of gastric cancer (GC) results largely from metastasis and chemotherapy resistance. Toward novel therapeutic strategies that target or evade these phenomena, we evaluated the function of the transcriptional regulator transducin (β)-like 1 X-linked receptor 1 (TBL1XR1) in GC cells, including stem-like cells. In this study, the correlation of expression of TBL1XR1 and clinical features and GC patients' outcomes was evaluated. Knockdown or exogenous expression of TBL1XR1 was combined with in vitro (2D and 3D cultures) and in vivo (mouse lung and lymphatic metastasis models) assays to evaluate the function of TBL1XR1. TBL1XR1's downstream signaling was delineated by phospho-kinase array and knockdown of candidate mediators. Analysis of clinical data showed that TBL1XR1 overexpression was correlated with worse prognosis. Functional assays showed that TBL1XR1 promoted stemness, epithelial-mesenchymal transition (EMT), and lung and lymphatic metastasis in GC cells. TBL1XR1 activated ERK1/2-Sox2 signaling and was dependent on signaling via PI3K/AKT, in GC stem-like cells distinguished by CD44 expression. Moreover, inhibition of these signaling proteins reversed chemoresistance in in vitro and in vivo models. Taken together, our results indicate that TBL1XR1 promotes stemness and metastasis in GC, making it a potential prognostic indicator. The PI3K/AKT-TBL1XR1-ERK1/2-Sox2 axis may represent a target for the treatment of GC.

Multidrug Resistance of Gastric Cancer: The Mechanisms and Chinese Medicine Reversal Agents

Chemotherapy is the main clinical treatment method of gastric cancer. Multidrug resistance (MDR) has become a common phenomenon with the development of tumors, which alleviates the effect of chemotherapy and makes it difficult to break the bottleneck of survival rate of advanced gastric cancer. Therefore, the exploration of MDR reversal agents for gastric cancer is the focus and also the difficulty of current treatment. Currently, the researches on the mechanisms of drug resistance in gastric cancer have been continuously deepened, which reveal different pathways and targets of MDR, laying a solid foundation for studying reversal agents. As a kind of natural medicine, traditional Chinese medicine (TCM) owns the characteristics of low toxicity, high safety and effectiveness. It can inhibit the occurrence, growth and metastasis of tumors, and reverse MDR via multiple pathways and mechanisms, the pathological function of which has become a research hotspot in recent years. TCM reversers are mainly divided into Chinese medicine monomers, Chinese patent medicines, and Chinese herbal compounds. With certain quantity and advantage, TCM reversers for MDR play an important role in the clinical treatment and show great potential in gastric cancer.

K-Ras-ERK1/2 accelerates lung cancer cell development via mediating H3K18ac through the MDM2-GCN5-SIRT7 axis

Context: H3^K18ac is linked to gene expression and DNA damage. Nevertheless, whether H3^K18ac participates in regulating Ras-ERK1/2-affected lung cancer cell phenotypes remains unclear. Objective: We explored the effects of H3^K18ac on Ras-ERK1/2-affected lung cancer cell phenotypes. Material and methods: NCI-H2126 cells were transfected with, pEGFP-K-Ras^WT and pEGFP-K-Ras^G12V/T35S plasmids for 48 h, and transfection with pEGFP-N1 served as a blank control. Then H3^K18ac and AKT and ERK1/2 pathways-associated factors were examined. Different amounts of the H3^K18Q (0.5, 1, and 2 μg) plasmids and Ras^G12V/T35S were co-transfected into NCI-H2126 cells, cell viability, cell colonies and migration were analyzed for exploring the biological functions of H3^K18ac in NCI-H2126 cells. The ERK1/2 pathway downstream factors were detected by RT-PCR and ChIP assays. The regulatory functions of SIRT7, GCN5 and MDM2 in Ras-ERK1/2-regulated H3^K18ac expression were finally uncovered. Results: Ras^G12V/T35S transfection decreased the expression of H3^K18ac about 2.5 times compared with the pEGFP-N1 transfection group, and activated ERK1/2 and AKT pathways. Moreover, H3^K18ac reduced cell viability, colonies, migration, and altered ERK1/2 downstream transcription in NCI-H2126 cells. Additionally, SIRT7 knockdown increased H3^K18ac expression and repressed cell viability, migration and the percentage of cells in S phase by about 50% compared to the control group, as well as changed ERK1/2 downstream factor expression. Besides, Ras-ERK1/2 decreased H3^K18ac was linked to MDM2-regulated GCN5 degradation. Conclusion: These observations disclosed that Ras-ERK1/2 promoted the development of lung cancer via decreasing H3^K18ac through MDM2-mediated GCN5 degradation. These findings might provide a new therapeutic strategy for lung cancer.

2,4,6-Tribromophenol Exposure Decreases P-Glycoprotein Transport at the Blood-Brain Barrier

2,4,6-Tribromophenol (TBP, CAS No. 118-79-6) is a brominated chemical used in the production of flame-retardant epoxy resins and as a wood preservative. In marine environments, TBP is incorporated into shellfish and consumed by predatory fish. Food processing and water treatment facilities produce TBP as a byproduct. 2,4,6-Tribromophenol has been detected in human blood and breast milk. Biologically, TBP interferes with estrogen and thyroid hormone signaling, which regulate important transporters of the blood-brain barrier (BBB). The BBB is a selectively permeable barrier characterized by brain microvessels which are composed of endothelial cells mortared by tight-junction proteins. ATP-binding cassette (ABC) efflux transporters on the luminal membrane facilitate the removal of unwanted endobiotics and xenobiotics from the brain. In this study, we examined the in vivo and ex vivo effects of TBP on two important transporters of the BBB: P-glycoprotein (P-gp, ABCB1) and Multidrug Resistance-associated Protein 2 (MRP2, ABCC2), using male and female rats and mice. 2,4,6-Tribromophenol exposure ex vivo resulted in a time- (1-3 h) and dose- (1-100 nM) dependent decrease in P-gp transport activity. MRP2 transport activity was unchanged under identical conditions. Immunofluorescence and western blotting measured decreases in P-gp expression after TBP treatment. ATPase assays indicate that TBP is not a substrate and does not directly interact with P-gp. In vivo dosing with TBP (0.4 µmol/kg) produced decreases in P-gp transport. Co-treatment with selective protein kinase C (PKC) inhibitors prevented the TBP-mediated decreases in P-gp transport activity.

Role of microRNAs in drug resistance of gastric cancer cells

Drug therapy is an important component of comprehensive treatments for gastric cancer (GC), but drug resistance of cancer cells often leads to treatment failure. It is significant to explore the drug resistance mechanism of GC cells. It has been reported that microRNAs (miRNAs) are closely related to drug resistance in GC. However, there are many kinds of microRNAs, which possess complex mechanisms and are not widely applied in clinical patients, so there are still many areas to be investigated about the relationship between microRNAs and drug resistance in GC. In this review, we review the role of miRNAs in the formation of drug resistance and discuss the existing problems and future directions.

K-ras-ERK1/2 down-regulates H2A.XY142ph through WSTF to promote the progress of gastric cancer

Background

Histone H2AX phosphorylation at the site of Tyr-142 can participates in multiple biological progressions, which is including DNA repair. Ras pathway is closely involved in human cancers. Our study investigated the effects of Ras pathway via regulating H2AX.^Y142ph.

Methods

Gastric cancer cell line SNU-16 and MKN1 cells were transfected with Ras for G12D and T35S site mutation. The phosphorylation of H2A.X^Y142 and ERK1/2, WSTF and MDM2 was detected by western blot. Cell viability, cell colonies and migration was analyzed by MTT assay, soft-agar colony formation assay, and Transwell assay, respectively. The expression of Ras pathway related downstream factors, EYA3 and WSTF was detected by qRT-PCR. The relationship between Ras and downstream factors were detected by ChIP. The cell cycle progression was measured by flow cytometry.

Results

Ras^G12D/T35V transection decreased the phosphorylation of H2A.X^Y142 and activated phosphorylation of ERK-1/2. H2A.X^Y142 inhibited cell viability, colonies and migration. H2A.X^Y142ph altered the expression of Ras downstream factors. CHIP assay revealed that Ras^G12D/T35V could bind to the promoters of these Ras pathway downstream factors. Silence of EYA3 increased H2A.X^Y142ph and inhibited cell viability, migration and percent cells in S stage. Furthermore, silence of EYA3 also changed the downstream factors expression. WSTF and H2A.X^Y142ph revealed the similar trend and MDM2 on the opposite.

Conclusion

Ras/ERK signal pathway decreased H2A.X^Y142ph and promoted cell growth and metastasis. This Ras regulation process was down-regulated by the cascade of MDM2-WSTF-EYA3 to decrease H2A.X^Y142ph in SNU-16 cells.

ERK is a Pivotal Player of Chemo-Immune-Resistance in Cancer

The extracellular signal-related kinases (ERKs) act as pleiotropic molecules in tumors, where they activate pro-survival pathways leading to cell proliferation and migration, as well as modulate apoptosis, differentiation, and senescence. Given its central role as sensor of extracellular signals, ERK transduction system is widely exploited by cancer cells subjected to environmental stresses, such as chemotherapy and anti-tumor activity of the host immune system. Aggressive tumors have a tremendous ability to adapt and survive in stressing and unfavorable conditions. The simultaneous resistance to chemotherapy and immune system responses is common, and ERK signaling plays a key role in both types of resistance. In this review, we dissect the main ERK-dependent mechanisms and feedback circuitries that simultaneously determine chemoresistance and immune-resistance/immune-escape in cancer cells. We discuss the pros and cons of targeting ERK signaling to induce chemo-immune-sensitization in refractory tumors.

Traditional Chinese medicine-combination therapies utilizing nanotechnology-based targeted delivery systems: a new strategy for antitumor treatment

Cancer is a major public health problem, and is now the world’s leading cause of death. Traditional Chinese medicine (TCM)-combination therapy is a new treatment approach and a vital therapeutic strategy for cancer, as it exhibits promising antitumor potential. Nano-targeted drug-delivery systems have remarkable advantages and allow the development of TCM-combination therapies by systematically controlling drug release and delivering drugs to solid tumors. In this review, the anticancer activity of TCM compounds is introduced. The combined use of TCM for antitumor treatment is analyzed and summarized. These combination therapies, using a single nanocarrier system, namely codelivery, are analyzed, issues that require attention are determined, and future perspectives are identified. We carried out a systematic review of >280 studies published in PubMed since 1985 (no patents involved), in order to provide a few basic considerations in terms of the design principles and management of targeted nanotechnology-based TCM-combination therapies.

Effects of proton pump inhibitors on reversing multidrug resistance via downregulating V-ATPases/PI3K/Akt/mTOR/HIF-1α signaling pathway through TSC1/2 complex and Rheb in human gastric adenocarcinoma cells in vitro and in vivo

Background

Our study aimed to explore the effects of PPIs on reversing multidrug resistance (MDR) to chemotherapy in gastric cancer by inhibiting the expression of V-ATPases and the PI3K/Akt/mTOR/HIF-1α signal pathway.

Methods

The gastric cancer cell lines SGC7901 and the multidrug resistance cell lines SGC7901/MDR were pretreated by the pantoprazole or the esomeprazole, respectively. Real-time PCR was used to determine mRNA levels, and western blotting and immunofluorescent staining analyses were employed to determine the protein expressions and intracellular distributions of the V-ATPases, PI3K, Akt, mTOR, HIF-1α, P-gp and MRP1 before and after PPIs pretreatment. SGC7901/MDR cells were planted on the athymic nude mice. Then the effects of PPZ pretreatment and/or ADR were compared by determining the tumor size, tumor weight and nude mice weight.

Results

PPIs pretreatment could inhibit mRNA levels of V-ATPases, MDR1 and MRP1, PI3K, Akt, mTOR and HIF-1α. PPIs inhibited V-ATPases and down-regulated the expressions of P-gp and MRP1. And further to block the expression of mTOR by Rapamycin could obviously inhibit the expressions of HIF-1α, P-gp and MRP1 in a dose-dependent manner. Therefore, PPIs inhibited the expressions of V-ATPases and then reversed MDR of the chemotherapy in gastric cancer by inhibiting P-gp and MRP1, and it could be speculated that the mechanism might be closely related to down-regulating the PI3K/Akt/mTOR/HIF-1α signaling pathway. Meanwhile, PPIs also could inhibit the expressions of TSC1/TSC2 complex and Rheb which might be involved into regulating the signaling pathway intermediately. The weight growth rate of the mice bearing tumor in the treatment group was lower than that of the nude mice in the normal group, while the weight growth rate of the mice in control group was significantly lower than that of the normal group and the treatment group, presenting a downward trend.

Conclusion

Therefore, PPIs inhibited the expressions of V-ATPases and then reversed MDR of the chemotherapy in gastric cancer by inhibiting P-gp and MRP1, and it could be speculated that the mechanism might be closely related to down-regulating the PI3K/Akt/mTOR/HIF-1α signaling pathway, and also to inhibiting the expressions of TSC1/TSC2 complex and Rheb which might be involved into regulating the signaling pathway intermediately.

TIPE2 sensitizes osteosarcoma cells to cis-platin by down-regulating MDR1 via the TAK1- NF-κB and - AP-1 pathways

TIPE2 participates in multiple types of cancer development. However, its mechanism underlying chemoresistance in osteosarcoma has not been elucidated. Herein, we observed the expression of TIPE2 and MDR1 in cis-platin-resistant osteosarcoma tissues and cell lines. Compared to their matched sensitive cell lines and tissues, TIPE2 was downregulated while MDR1 expression was increased. Further investigation showed that overexpression of TIPE2 effectively inhibited MDR1 expression and greatly sensitized osteosarcoma cells to cis-platin, both in vivo and in vitro. Mechanistically, TIPE2 inhibited the transcription of the MDR1 promoter by interfering with the TAK1-NF-κB and -AP-1 pathways. Overall, our results elucidated for the first time that TIPE2 sensitizes osteosarcoma cells to cis-platin through downregulation of MDR1 and may be a novel target in osteosarcoma therapy.

UBE2C Is a Potential Biomarker of Intestinal-Type Gastric Cancer With Chromosomal Instability

This study explored potential biomarkers associated with Lauren classification of gastric cancer. We screened microarray datasets on gastric cancer with information of Lauren classification in gene expression omnibus (GEO) database, and compared differentially expressing genes between intestinal-type or diffuse-type gastric cancer. Four sets of microarray data (GSE2669, GSE2680, GDS3438, and GDS4007) were enrolled into analysis. By differential gene analysis, UBE2C, CDH1, CENPF, ERO1L, SCD, SOX9, CKS1B, SPP1, MMP11, and ANLN were identified as the top genes related to intestinal-type gastric cancer, and MGP, FXYD1, FAT4, SIPA1L2, MUC5AC, MMP15, RAB23, FBLN1, ANXA10, and ADH1B were genes related to diffuse-type gastric cancer. We comprehensively validated the biological functions of the intestinal-type gastric cancer related gene UBE2C and evaluated its clinical significance on 1,868 cases of gastric cancer tissues from multiple medical centers of Shanghai, China. The gain of copy number on 20q was found in 4 out of 5 intestinal-type cancer cell lines, and no similar copy number variation (CNV) was found in any diffuse-type cancer cell line. Interfering UBE2C expression inhibited cell proliferation, migration and invasion in vitro, and tumorigenesis in vivo. Knockdown of UBE2C resulted in G2/M blockage in intestinal-type gastric cancer cells. Overexpression of UBE2C activated ERK signal pathway and promoted cancer cell proliferation. U0126, an inhibitor of ERK signaling pathway reversed the oncogenic phenotypes caused by UBE2C. Moreover, overexpression of UBE2C was identified in human intestinal-type gastric cancer. Overexpression of UBE2C protein predicted poor clinical outcome. Taken together, we characterized a group of Lauren classification-associated biomarkers, and clarified biological functions of UBE2C, an intestinal-type gastric cancer associated gene. Overexpression of UBE2C resulted in chromosomal instability that disturbed cell cycle and led to poor prognosis of intestinal-type gastric cancer.

Arsenic trioxide attenuates STAT-3 activity and epithelial-mesenchymal transition through induction of SHP-1 in gastric cancer cells

BACKGROUND

We investigated the effect of arsenic trioxide (ATO) for inhibition of signal transducer and activator of transcription 3 (STAT3) and epithelial-mesenchymal transition (EMT) in gastric cancer cells, and the role of SH2 domain-containing phosphatase-1 (SHP-1) during this process.

METHODS

We used AGS cells, which showed minimal SHP-1 expression and constitutive STAT3 expression. After treatment of ATO, cellular migration and invasion were assessed by using wound closure assay, Matrigel invasion assay and 3-D culture invasion assay. To validate the role of SHP-1, pervanadate, a pharmacologic phosphatase inhibitor, and SHP-1 siRNA were used. Xenograft tumors were produced, and ATO or pervanadate were administered via intraperitoneal (IP) route.

RESULTS

Treatment of ATO 5 and 10 μM significantly decreased cellular migration and invasion in a dose-dependent manner. Western blot showed that ATO upregulated SHP-1 expression and downregulated STAT3 expression, and immunofluorescence showed upregulation with E-cadherin (epithelial marker) and downregulation of Snail1 (mesenchymal marker) expression by ATO treatment. Anti-migration and invasion effect and modulation of SHP-1/STAT3 axis by ATO were attenuated by pervanadate or SHP-1 siRNA. IP injection of ATO significantly decreased the xenograft tumor volume and upregulated SHP-1 expression, which were attenuated by co-IP injection of pervanadate.

CONCLUSION

Our data suggest that ATO inhibits STAT3 activity and EMT process by upregulation of SHP-1 in gastric cancer cells.

A systematic review and meta-analysis of bidirectional effect of arsenic on ERK signaling pathway

Arsenic is a toxic metal, which ultimately leads to cell apoptosis. ERK is considered a key transcriptional regulator of arsenic‑induced apoptosis. Due to a few controversial issues about arsenic‑mediated extracellular signal‑regulated MAP kinases (ERK) signaling, a meta‑analysis was performed. Subgroup analyses demonstrated that high doses (≥2 µmol/l) of arsenic increased the expression of Ras, ERK, ERK1, ERK2, phosphorylated (p)‑ERK, p‑ERK1, and p‑ERK2, while low doses (<2 µmol/l) decreased the expression of Ras, ERK1, p‑ERK, and p‑ERK2 when compared to control groups. Long term exposure (>24 h) to arsenic led to inhibition of expression of ERK1, p‑ERK1, and p‑ERK2, whereas short‑term exposure (≤24 h) triggered the expression of ERK1, ERK2, p‑ERK, p‑ERK1, and p‑ERK2. Furthermore, normal cells exposed to arsenic exhibited higher production levels of Ras and p‑ERK. Conversely, exposure of cancer cells to arsenic showed a lower level of production of Ras and p‑ERK as well as higher level of p‑ERK1 and p‑ERK2 as compared to control group. Short‑term exposure of normal cells to high doses of arsenic may promote ERK signaling pathway. In contrast, long‑term exposure of cancer cells to low doses of arsenic may inhibit ERK signaling pathway. This study may be helpful in providing a theoretical basis for the diverging result of arsenic adverse effects on one hand and therapeutic mechanisms on the other concerning arsenic‑induced apoptosis.

Arsenic trioxide potentiates the effectiveness of etoposide in Ewing sarcomas

Ewing sarcomas (ES) are rare mesenchymal tumours, most commonly diagnosed in children and adolescents. Arsenic trioxide (ATO) has been shown to efficiently and selectively target leukaemic blasts as well as solid tumour cells. Since multidrug resistance often occurs in recurrent and metastatic ES, we tested potential additive effects of ATO in combination with the cytostatic drugs etoposide and doxorubicin. The Ewing sarcoma cell lines A673, RD-ES and SK-N-MC as well as mesenchymal stem cells (MSC) for control were treated with ATO, etoposide and doxorubicin in single and combined application. Viability and proliferation (MTS assay, colony formation, 3D spheroid culture) as well as cell death induction (western blot analysis, flow cytometry) were analysed. In the MTS viability assays ATO treatment significantly reduced the metabolic activity of all three ES cell lines (A673, RD-ES and SK-N-MC) examined. Moreover, all ES cell lines were sensitive to etoposide, whereas MSC remained unaffected by the drug concentrations used. With the exception of ATO in RD-ES cells, all drugs induced apoptosis in the ES cell lines, indicated by caspase-3 and PARP cleavage. Combination of the agents potentiated the reduction of viability as well as the inhibitory effect on clonal growth. In addition, cell death induction was obviously enhanced in RD-ES and SK-N-MC cells by a combination of ATO and etoposide compared to single application. Summarised, the combination of low dose, physiologically easily tolerable ATO with commonly used etoposide and doxorubicin concentrations efficiently and selectively suppressed viability and colony formation in ES cell lines, whereas a combination of ATO and etoposide was favourable for cell death induction. In addition to an increase of the effectiveness of the cytostatic drugs and prevention of potential drug resistance, this approach may also reduce toxicity effects, since the individual doses can be reduced.

Effect of miR-155 knockdown on the reversal of doxorubicin resistance in human lung cancer A549/dox cells

Doxorubicin has been widely used in the treatment of cancer. However, acquired doxorubicin resistance severely hinders the application of the drug. In the present study, doxorubicin resistance was investigated in lung carcinoma. microRNA-155 (miR-155) was found to be upregulated in the doxorubicin-resistant A549/dox cell line. Suppression of miR-155 in this cell line considerably reversed doxorubicin resistance, and doxorubicin-induced apoptosis and cell cycle arrest were recovered. Furthermore, reverse transcription-polymerase chain reaction and western blot analysis revealed that miR-155 suppression downregulated the expression of multidrug resistance protein 1, multidrug resistance-associated protein 1, breast cancer resistance protein, glutathione S-transferase-π, Survivin and B-cell lymphoma 2, and upregulated the expression of caspase-3 and caspase-8. In addition, it was found that miR-155 suppression inhibited the activation of AKT and extracellular signal-regulated kinase. The transcriptional activity of nuclear factor-κB and activator protein-1 was also downregulated. In summary, the present results indicate that miR-155 may participate in doxorubicin resistance in lung carcinoma. The current study provides a novel target for lung carcinoma treatment.