MDR1-P-glycoprotein behaves as an oncofetal protein that promotes cell survival in gastric cancer cells

P-glycoprotein (P-gp)-driven cancer drug resistance: biological profile, non-coding RNAs, drugs and nanomodulators

Drug resistance has compromised the efficacy of chemotherapy. The dysregulation of drug transporters including P-glycoprotein (P-gp) can mediate drug resistance through drug efflux. In this review, we highlight the role of P-gp in cancer drug resistance and the related molecular pathways, including phosphoinositide 3-kinase (PI3K)-Akt, phosphatase and tensin homolog (PTEN) and nuclear factor-κB (NF-κB), along with non-coding RNAs (ncRNAs). Extracellular vesicles secreted by the cells can transport ncRNAs and other proteins to change P-gp activity in cancer drug resistance. P-gp requires ATP to function, and the induction of mitochondrial dysfunction or inhibition of glutamine metabolism can impair P-gp function, thus increasing chemosensitivity. Phytochemicals, small molecules and nanoparticles have been introduced as P-gp inhibitors to increase drug sensitivity in human cancers.

Unlocking mitochondrial drug targets: The importance of mitochondrial transport proteins

A disturbed mitochondrial function contributes to the pathology of many common diseases. These organelles are therefore important therapeutic targets. On the contrary, many adverse effects of drugs can be explained by a mitochondrial off-target effect, in particular, due to an interaction with carrier proteins in the inner membrane. Yet this class of transport proteins remains underappreciated and understudied. The aim of this review is to provide a deeper understanding of the role of mitochondrial carriers in health and disease and their significance as drug targets. We present literature-based evidence that mitochondrial carrier proteins are associated with prevalent diseases and emphasize their potential as drug (off-)target sites by summarizing known mitochondrial drug-transporter interactions. Studying these carriers will enhance our knowledge of mitochondrial drug on- and off-targets and provide opportunities to further improve the efficacy and safety of drugs.

Pharmacokinetics and tissue distribution of 12 major active components in normal and chronic gastritis rats after oral administration of Weikangling capsules

ETHNOPHARMACOLOGICAL RELEVANCE

Weikangling Capsules (WKLCs) have been used in the clinic for the treatment of gastrointestinal disorders for more than 30 years. However, the pharmacokinetic characteristics and tissue distribution of its major bioactive components in rats under different physiological and pathological conditions are unclear.

AIM OF THE STUDY

In this study, we aimed to clarify the differences in pharmacokinetic parameters and tissue distribution of the major active components in WKLCs under physiological and pathological states.

MATERIALS AND METHOD

Normal and ethanol-induced chronic gastritis rats received 2.16 g/kg WKLCs by gavage, and urine, feces, plasma, and tissue (heart, liver, spleen, lung, kidney, stomach, and small intestine) samples were obtained. The active components in urine, feces and plasma were detected by ultra-high-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS). A rapid and sensitive analytical method, ultra-high-performance liquid chromatography coupled with triple-quadrupole linear ion-trap tandem mass spectrometry (UHPLC-QTRAP-MS/MS), was established and validated to clarify and compare the pharmacokinetics and tissue distribution of the major active components in normal and chronic gastritis rats.

RESULTS

A total of 36 chemical components in the feces, urine, and plasma of chronic gastritis rats were identified by UHPLC-Q-TOF-MS/MS. Among them, 20 were the prototype components of WKLCs, and 16 were metabolites. The pharmacokinetic characteristics and tissue distribution of 12 prototype components were successfully analyzed by UHPLC-QTRAP-MS/MS. The pharmacokinetic results showed that the C_max, AUC_0-t, and AUC_0-∞ of paeoniflorin, glycyrrhizic acid, and glycyrrhetinic acid were distinctly higher than those of the other components in normal and chronic gastritis rats. Compared to normal rats, the C_max, AUC_0-t, and AUC_0-∞ of albiflorin, liquiritin apioside, liquiritin, isoliquiritin, ononin, isoliquiritigenin, dactylorhin A, and glycyrrhizic acid were significantly increased in chronic gastritis rats (P < 0.05), while the C_max, AUC_0-t and AUC_0-∞ of militarine and liquiritigenin had significantly lower decreases in chronic gastritis rats (P < 0.05). The results of the tissue distribution showed that the 12 components were widely distributed in the heart, liver, spleen, lung, kidney, stomach, and small intestine of rats, of which the liver, kidney, stomach, and small intestine were the main accumulative organs. Compared with normal rats, the concentrations of 12 components in the liver, kidney, stomach, and small intestine of chronic gastritis rats were widely higher than those of normal rats at the same time points.

CONCLUSION

The pharmacokinetic characteristics and tissue distribution of 12 active components of WKLCs were comprehensively characterized and elucidated in normal and chronic gastritis rats. These findings laid a solid foundation for revealing the pharmacodynamic material basis of WKLCs in treating gastrointestinal disorders.

P-glycoprotein and cancer: what do we currently know?

Acquired resistance during cancer treatment is unfortunately a frequent event. There are several reasons for this, including the ability of the ATP-binding cassette transporters (ABC transporters), which are integral membrane proteins, to export chemotherapeutic molecules from the interior of the tumor cells. One important member of this family is the protein known as Permeability Glycoprotein (P-Glycoprotein, P-gp or ABCB1). Its clinical relevance relies mainly on the fact that the inhibition of P-gp and other ABC transporters could result in the reversal of the multidrug resistance (MDR) phenotype in some patients. Recently, other roles apart from being a key player in MDR, have emerged for P-gp. Therefore, this review discusses the relationship between P-gp and MDR, in addition to the possible role of this protein as a biomarker in cancer.

Expression of Chemoresistance-Associated ABC Proteins in Hepatobiliary, Pancreatic and Gastrointestinal Cancers

Simple Summary

One-third of the approximately 10 million deaths yearly caused by cancer worldwide are due to hepatobiliary, pancreatic, and gastrointestinal tumors. One primary reason for this high mortality is the lack of response of these cancers to pharmacological treatment. More than 100 genes have been identified as responsible for seven mechanisms of chemoresistance, but only a few of them play a critical role. These include ABC proteins (mainly MDR1, MRP1-6, and BCRP), whose expression pattern greatly determines the individual sensitivity of each tumor to pharmacotherapy.

Abstract

Hepatobiliary, pancreatic, and gastrointestinal cancers account for 36% of the ten million deaths caused by cancer worldwide every year. The two main reasons for this high mortality are their late diagnosis and their high refractoriness to pharmacological treatments, regardless of whether these are based on classical chemotherapeutic agents, targeted drugs, or newer immunomodulators. Mechanisms of chemoresistance (MOC) defining the multidrug resistance (MDR) phenotype of each tumor depend on the synergic function of proteins encoded by more than one hundred genes classified into seven groups (MOC1-7). Among them, the efflux of active agents from cancer cells across the plasma membrane caused by members of the superfamily of ATP-binding cassette (ABC) proteins (MOC-1b) plays a crucial role in determining tumor MDR. Although seven families of human ABC proteins are known, only a few pumps (mainly MDR1, MRP1-6, and BCRP) have been associated with reducing drug content and hence inducing chemoresistance in hepatobiliary, pancreatic, and gastrointestinal cancer cells. The present descriptive review, which compiles the updated information on the expression of these ABC proteins, will be helpful because there is still some confusion on the actual relevance of these pumps in response to pharmacological regimens currently used in treating these cancers. Moreover, we aim to define the MOC pattern on a tumor-by-tumor basis, even in a dynamic way, because it can vary during tumor progression and in response to chemotherapy. This information is indispensable for developing novel strategies for sensitization.

PLCγ1 inhibition-driven autophagy of IL-1β-treated chondrocyte confers cartilage protection against osteoarthritis, involving AMPK, Erk and Akt

Previous studies identified the involvement of phosphoinositide‐specific phospholipase C (PLC) γ1 in some events of chondrocytes. This study aims to investigate whether and how PLCγ1 modulates autophagy to execute its role in osteoarthritis (OA) progression. Rat normal or human OA chondrocytes were pretreated with IL‐1β for mimicking or sustaining OA pathological condition. Using Western blotting, immunoprecipitation, qPCR, immunofluorescence and Dimethylmethylene blue assays, and ELISA and transmission electron microscope techniques, we found that PLCγ1 inhibitor U73122 enhanced Collagen II, Aggrecan and GAG levels, accompanied with increased LC3B‐II/I ratio and decreased P62 expression level, whereas autophagy inhibitor Chloroquine partially diminished its effect. Meanwhile, U73122 dissociated Beclin1 from Beclin1‐IP3R‐Bcl‐2 complex and blocked mTOR/ULK1 axis, in which the crosstalk between PLCγ1, AMPK, Erk and Akt were involved. Additionally, by haematoxylin and eosin, Safranin O/Fast green, and immunohistochemistry staining, we observed that intra‐articular injection of Ad‐shPLCγ1‐1/2 significantly enhanced Collagen and Aggrecan levels, accompanied with increased LC3B and decreased P62 levels in a rat OA model induced by anterior cruciate ligament transection and medial meniscus resection. Consequently, PLCγ1 inhibition‐driven autophagy conferred cartilage protection against OA through promoting ECM synthesis in OA chondrocytes in vivo and in vitro, involving the crosstalk between PLCγ1, AMPK, Erk and Akt.

A Review of Research Progress in Multidrug-Resistance Mechanisms in Gastric Cancer

Gastric cancer is one of the most common malignant tumors, and it is also one of the leading causes of cancer death worldwide. Because of its insidious symptoms and lack of early dictation screening, many cases of gastric cancer are at late stages which make it more complicated to cure. For these advanced-stage gastric cancers, combination therapy of surgery, chemotherapy, radiotherapy and target therapy would bring more benefit to the patients. However, the drug-resistance to the chemotherapy restricts its effect and might lead to treatment failure. In this review article, we discuss the mechanisms which have been found in recent years of drug resistance in gastric cancer. And we also want to find new approaches to counteract chemotherapy resistance and bring more benefits to the patients.

The Association between ABCB1 C1236T/C3435T SNPs and H. pylori Infection among Jordanians

Infection with Helicobacter pylori (H. pylori) is very common and affecting about 50% of the worldwide population. Several genetic variations have been implicated in determining the clinical susceptibility to this infection. In the current study, we examined the association between C1236T (rs1045642) and C3435T (rs1045642) single nucleotide polymorphisms (SNPs) in the ABCB1 gene and the prevalence of H. pylori infection among Jordanians. A total of 412 subjects (257 H. pylori-positive cases and 155 H. pylori-negative controls) were recruited and participated in the study, and the genotyping of the ABCB1 gene was performed using RFLP-PCR techniques. A significant association was detected between C1236T and H. pylori infection (p < 0.01). The frequency of CT genotype was significantly higher in the positive cases (40.1%) compared to the controls (21.3%). In addition, the C3435T SNP was weakly associated with H. pylori infection (p = 0.077). Haplotype analysis of C1236T and C3435T SNPs showed that the TT haplotype was present in 22.7% of the positive cases compared to 30.7% of the negative controls (p < 0.05, odds ratio = 0.663, 95% CI: (0.483-0.911)). Consequently, the TT haplotype seems to decrease the risk of H. pylori infection. In conclusion, the current results suggest an association between ABCB1 SNPs and H. pylori infection in the Jordanian population.

IL-1β receptor antagonist (IL-1Ra) combined with autophagy inducer (TAT-Beclin1) is an effective alternative for attenuating extracellular matrix degradation in rat and human osteoarthritis chondrocytes

Background

Autophagy induction is an effective approach for OA therapy. IL-1β is one of the major inflammatory cytokines linked to OA pathological progression, and its receptor blockade interrupts OA cartilage destruction. The objective of this study was to decipher the link between autophagy and regulatory mechanism of IL-1β and to investigate the effect of IL-1β receptor blockade by IL-1 receptor antagonist (IL-1Ra) combined with or without an autophagy inducer (TAT-Beclin1) on extracellular matrix (ECM) in OA chondrocytes in vitro and in vivo.

Methods

IL-1β-treated rat and human OA chondrocytes were cultured in response to IL-1Ra. The expression and distribution of signal molecules regulating ECM synthesis and autophagy were investigated via western blotting, immunoprecipitation, real-time PCR, immunofluorescence, and transmission electron microscope technique. Furthermore, after intra-articular injection of IL-1Ra, TAT-Beclin1, and a combination of both in a rat OA model established by anterior cruciate ligament transection and medial meniscus resection, the morphological changes of cartilage and related signal molecule expression levels were monitored using H.E., Safranin O-Fast green, and immunohistochemistry staining.

Results

Reduced autophagy by IL-1β contributed to ECM degradation, and blockade of IL-1β by IL-1Ra restored autophagy and attenuated ECM degradation in rat and human OA chondrocytes, as well as in a rat OA model. Akt/mTOR/ULK1, Akt/mTOR/NF-κB, and LC3B deacetylation were involved in autophagy regulated by IL-1β. Intra-articular injection of IL-1Ra combined with TAT-Beclin1 was more effective than IL-1Ra alone.

Conclusions

IL-1Ra restored autophagy and attenuated ECM degradation, with an implication that blocking IL-1β combined with enhancing autophagy might be a potential therapeutic strategy for OA.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1952-5) contains supplementary material, which is available to authorized users.

Mitochondria P-glycoprotein confers paclitaxel resistance on ovarian cancer cells

Background: Subcellular expression of P-glycoprotein (P-gp) may play an essential role in multidrug resistance (MDR) in many cancers. However, the mitochondria expression and functional activity of P-gp in ovarian cancer are still unclear. In this study, we isolated mitochondria from A2780 cell line and its paclitaxel-resistant subline A2780T and investigated the expression and function of mitochondria P-gp. Methods: Immunocytochemistry was used to evaluate P-gp expression and subcellular localization in cancer cells. Immunofluorescence and laser confocal microscopy were used to detect the co-localization of P-gp and mitochondria both in ovarian cancer tissues and in cell lines. Western blotting (WB), transmission electron microscopy and JC-1 kit were used to evaluate the purity, integrity and activity of the isolated mitochondria. P-gp expression in the whole cell and the isolated mitochondria was evaluated by WB. Flow cytometry was used to evaluate the efflux function of mitochondria P-gp. Results: P-gp expression was detected at the membrane, cytoplasm and nuclei of the A2780T cells, but not in the A2780 cells. Co-localization of P-gp and mitochondria was observed in the A2780T cell line and ovarian cancer tissues, but not in A2780 cells. The purity, integration and activity of the isolated mitochondria are high. P-gp was highly expressed in the A2780T cells and the isolated mitochondria, but was not found in A2780 cells. Rho123 efflux rate was significantly increased in isolated A2780T mitochondria compared to those in A2780 (43.2% vs 9.6%), but it was partly reversed by cyclosporin A (CsA, a P-gp inhibitor). Conclusion: P-gp is highly expressed in mitochondria of taxol-resistant ovarian cancer cells and ovarian cancer tissues and mediates the drug efflux, which probably protect cancer cells from chemotherapy.

Ubenimex Reverses MDR in Gastric Cancer Cells by Activating Caspase-3-Mediated Apoptosis and Suppressing the Expression of Membrane Transport Proteins

Gastric cancer (GC) is one of the most malignant tumors, accounting for 10% of deaths caused by all cancers. Chemotherapy is often necessary for treatment of GC; the FOLFOX regimen is extensively applied. However, multidrug resistance (MDR) of GC cells prevents wider application of this treatment. Ubenimex, an inhibitor of CD13, is used as an immune adjuvant to treat hematological malignancies. Here, we demonstrate that CD13 expression positively correlates with MDR development in GC cells. Moreover, Ubenimex reverses the MDR of SGC7901/X and MKN45/X cells and enhances their sensitivity to FOLFOX, in part by decreasing CD13 expression, which is accompanied by downregulation of Bcl-xl, Bcl-2, and survivin expression; increased expression of Bax; and activation of the caspase-3-mediated apoptotic cascade. In addition, Ubenimex downregulates expression of membrane transport proteins, such as P-gp and MRP1, by inhibiting phosphorylation in the PI3K/AKT/mTOR pathway to increase intracellular accumulations of 5-fluorouracil and oxaliplatin, a process for which downregulation of CD13 expression is essential. Therefore, the present results reveal a previously uncharacterized function of CD13 in promoting MDR development in GC cells and suggest that Ubenimex is a candidate for reversing the MDR of GC cells.

Subcellular drug distribution: mechanisms and roles in drug efficacy, toxicity, resistance, and targeted delivery

After administration, drug molecules usually enter target cells to access their intracellular targets. In eukaryotic cells, these targets are often located in organelles, including the nucleus, endoplasmic reticulum, mitochondria, lysosomes, Golgi apparatus, and peroxisomes. Each organelle type possesses unique biological features. For example, mitochondria possess a negative transmembrane potential, while lysosomes have an intraluminal delta pH. Other properties are common to several organelle types, such as the presence of ATP-binding cassette (ABC) or solute carrier-type (SLC) transporters that sequester or pump out xenobiotic drugs. Studies on subcellular drug distribution are critical to understand the efficacy and toxicity of drugs along with the body's resistance to them and to potentially offer hints for targeted subcellular drug delivery. This review summarizes the results of studies from 1990 to 2017 that examined the subcellular distribution of small molecular drugs. We hope this review will aid in the understanding of drug distribution within cells.

Nrf2 overexpression is associated with P-glycoprotein upregulation in gastric cancer

The efficacy of chemotherapeutic agents remains very poor in gastric cancer (GC) patients due to the development of multidrug resistance (MDR) phenotype. The nuclear factor erythroid 2-related factor 2 (Nrf2), is a pivotal transcriptional factor that regulates phase II detoxifying enzymes, antioxidants and efflux transporters including P-glycoprotein (P-gp). The aim of this study was to investigate the association of Nrf2 and P-gp and their correlations with clinicopathological criteria in GC patients.Nrf2 and MDR1/P-gp expressions in both mRNA and protein levels were examined by real-time PCR and immunohistochemical staining (IHC) respectively, in endoscopic biopsy samples from60 GC patients compared with those expressions in non-GC individuals. Our results from IHC examinations revealed that Nrf2 expression in GC patients (46.7%) is markedly higher than that in non-GC individuals (11.7%) (p<0.001, Mann-Whitney test) which was confirmed by real-time PCR in mRNA levels. Induction of P-gp as a drug efflux pump, was associated with Nrf2 overexpression in these samples (r=0.55, p<0.001). There was also a strong correlation between Nrf2 overexpression and tumor size, histological grade, lymph node and distant metastasis while P-gp upregulation was shown to be associated only with the histological grade and tumor size (Chi-square, all p<0.05). Our results suggest that therapeutic inhibition of Nrf2 expression can improve the efficacy of chemotherapeutic agents for GC patients by down regulation of P-gp expression.

Phosphoinositide-specific phospholipase Cγ1 inhibition induces autophagy in human colon cancer and hepatocellular carcinoma cells

Phosphoinositide-specific phospholipase C (PLC) γ1 has been reported to be involved in cancer cell proliferation and metastasis. However, whether PLCγ1 modulates autophagy and the underlying mechanism remains unclear. Here, we investigated the relationship between PLCγ1 and autophagy in the human colon cancer cell line HCT116 and hepatocellular carcinoma cell line HepG2. The results indicated that PLCγ1 inhibition via lentivirus-mediated transduction with shRNA/PLCγ1 or transient transfection with pRK5-PLCγ1 (Y783A) vector increased LC3B-II levels and the number of autophagic vacuoles and decreased p62 levels. Addition of an autophagy inhibitor led to LC3B and p62 accumulation. Furthermore, AMPK activation promoted the autophagy induced by PLCγ1 inhibition by blocking the FAK/PLCγ1 axis. In addition, PLCγ1 inhibition either blocked the mTOR/ULK1 axis or enhanced dissociation of the Beclin1-IP3R-Bcl-2 complex to induce autophagy. Taken together, our findings revealed that PLCγ1 inhibition induced autophagy and the FAK/PLCγ1 axis is a potential downstream effector of the AMPK activation-dependent autophagy signalling cascade. Both blockade of the mTOR/ULK1 axis and dissociation of the Beclin1-IP3R-Bcl-2 complex contributed to the induction of autophagy by PLCγ1 inhibition. Consequently, these findings provide novel insight into autophagy regulation by PLCγ1 in colon cancer and hepatocellular carcinoma cells.

Current situation and trend of research for drug resistance in gastric cancer

Drug resistance of gastric cancer cells is one of the main reasons that lead to failure of chemotherapy in gastric cancer. Gastric cancer cells can be resistant to chemotherapeutic drugs and targeted drugs, which leads to poor therapeutic effects. Although the mechanisms of drug resistance of gastric cancer cells have long been investigated, no effective drug that can reverse the drug resistance of gastric cancer cells has been found. Therefore, it is important to reverse the drug resistance of gastric cancer cells to improve the prognosis of gastric cancer. In this paper, we review the mechanisms of drug resistance of gastric cancer cells to chemotherapeutic drugs and targeted drugs, summarize current situation for research of drug resistance of gastric cancer cells, and discuss the future development direction in this field.

An increase in glucosylceramide synthase induces Bcl-xL-mediated cell survival in vinorelbine-resistant lung adenocarcinoma cells

Reversing drug resistance with concurrent treatment confers anticancer benefits. In this study, we investigated the potential mechanism of glucosylceramide synthase (GCS)-mediated vinca alkaloid vinorelbine (VNR) resistance in human lung adenocarcinoma cells. Compared with PC14PE6/AS2 (AS2) and CL1-0 cells, apoptotic analysis showed that both A549 and CL1-5 cells were VNR-resistant, while these cells highly expressed GCS at the protein level. VNR treatment significantly converts ceramide to glucosylceramide in VNR-resistant cells; however, pharmacologically inhibiting GCS with (±)-threo-1-Phenyl-2-decanoylamino-3-morpholino-1-propanol hydrochloride (PDMP) induced ceramide accumulation, accompanied by a decrease in glucosylceramide. Under concurrent treatment with VNR and PDMP, an increase in cell apoptosis could be identified; furthermore, genetically silencing GCS confirmed these effects. In VNR-resistant cells, Bcl-xL expression was aberrantly increased, while pharmacologically inhibiting Bcl-xL with ABT-737 sensitized cells to VNR-induced apoptosis. Conversely, enforced expression of Bcl-xL strengthened the survival response of the VNR-susceptible cells AS2 and CL1-0. Without changes in mRNA expression, Bcl-xL was overexpressed independent of β-catenin-mediated transcriptional regulation in VNR-resistant cells. Simultaneous GCS inhibition and VNR treatment caused a decrease in Bcl-xL expression. According to these findings, an increase in GCS caused Bcl-xL augmentation, facilitating VNR resistance in lung adenocarcinoma cells.

Elevated STAT3 Signaling-Mediated Upregulation of MMP-2/9 Confers Enhanced Invasion Ability in Multidrug-Resistant Breast Cancer Cells

The development of multidrug resistance greatly impedes effective cancer therapy. Recent advances in cancer research have demonstrated that acquisition of multidrug resistance by cancer cells is usually accompanied by enhanced cell invasiveness. Several lines of evidence indicated that cross activation of other signaling pathways during development of drug resistance may increase invasive potential of multidrug-resistant (MDR) cancer cells. However, the accurate mechanism of this process is largely undefined. In this study, to better understand the associated molecular pathways responsible for cancer progression induced by drug resistance, a MDR human breast cancer cell line SK-BR-3/EPR with P-glycoprotein overexpression was established using stepwise long-term exposure to increasing concentration of epirubicin. The SK-BR-3/EPR cell line exhibited decreased cell proliferative activity, but enhanced cell invasive capacity. We showed that the expression of metastasis-related matrix metalloproteinase (MMP)-2/9 was elevated in SK-BR-3/EPR cells. Moreover, SK-BR-3/EPR cells showed elevated activation of STAT3. Activation of STAT3 signaling is responsible for enhanced invasiveness of SK-BR-3/EPR cells through upregulation of MMP-2/9. STAT3 is a well-known oncogene and is frequently implicated in tumorigenesis and chemotherapeutic resistance. Our findings augment insight into the mechanism underlying the functional association between MDR and cancer invasiveness.

Role of RNA-interference-induced zinc finger protein 139 suppression in gastric cancer cell sensitivity to chemotherapeutic agents

Zinc finger proteins (ZNFs) are a class of proteins widely distributed in the human genome, which have been found to play a role in the regulation of gene transcription and the occurrence and development of gastric cancer (GC). ZNF139 was found to be associated with GC in our previous experiments. The present study aimed to analyse the differences in ZNF139 protein expression in SGC7901 GC cells and in situ grafted GC tumors in nude mice prior to and following RNA interference inhibition, and to investigate the mechanisms underlying ZNF139 involvement in the occurrence, development and chemosensitivity of GC. A ZNF139-targeted small interfering (si)RNA plasmid was constructed and transfected into the cancer cells and in situ grafted tumors. The MTT assay was used to investigate the alterations in chemosensitivity prior to and following transfection of siRNA-ZNF139. The two-dimensional difference gel electrophoresis and liquid chromatography-mass spectrometry techniques were used to identify the different protein points prior to and following siRNA-ZNF139 transfection. Western blot analysis was performed to confirm the identified proteins. In the siRNA-ZNF139 group, the growth of the cancer cells and in situ grafted tumors significantly decreased. However, the post-interference chemosensitivity to 5-fluorouracil, cisplatin and mitomycin C significantly increased. In the in vivo and in vitro experiments, the expression of pyridoxal kinase (PDXK) was upregulated, whereas the expression levels of annexin A2 (ANXA2) and fascin were downregulated following transfection. Western blot analysis confirmed the results for PDXK, ANXA2 and fascin by proteomics. Therefore, ZNF139 may participate in the occurrence, development and chemosensitivity of GC by promoting the expression of ANXA2 and fascin, while inhibiting the expression of PDXK.

XRCC1 genetic polymorphism acts a potential biomarker for lung cancer

Lung cancer is one of the most common but serious cancers in the world. Both the X-ray repair cross-complementing group 1 (XRCC1) gene and the human multidrug resistance 1 (MDR1) gene are important candidate genes influencing the susceptibility to various diseases, including lung cancer. This study aimed to assess the correlation of genetic polymorphisms in XRCC1 and MDR1 with the susceptibility to lung cancer. In this study, a total of 320 lung cancer patients and 346 cancer-free controls in Chinese population were enrolled in this study. Data about the clinical characteristics and related risk factors of lung cancer were collected by questionnaires. The single-nucleotide polymorphisms (SNPs) of XRCC1 and MDR1 genes were genotyped by created restriction site-polymerase chain reaction method. Our data showed that the risk for lung cancer increased significantly among the variant Arg194Trp (C > T, rs1799782) and Arg399Gln (G > A, rs25487) of XRCC1, but there are no significant differences in the allelic and genotypic frequencies of c.1564A > T and c.3073A > C of MDR1 between lung cancer patients and cancer-free controls. In conclusion, these preliminary results suggest that the C > T, rs1799782 and C > T, rs25487 of XRCC1 genetic variants might be used as molecular markers for detecting lung cancer susceptibility.

Association between Virulence Factors and TRAF1/4-1BB/Bcl-xL Expression in Gastric Mucosa Infected with Helicobacter pylori

Objective. CagA+/vacAs1+/vacAm1+ Helicobacter pylori upregulates the expression of tumor necrosis factor receptor-associated factor 1 (TRAF1), tumor necrosis factor receptor superfamily member 9 (4-1BB), and B-cell lymphoma-extra large (Bcl-xL) in human gastric epithelial cells. We investigated the correlation between cagA/vacAs1/vacAm1 and TRAF1/4-1BB/Bcl-xL expression in gastric mucosal tissue of patients with gastric disorders. Methods. We collected gastric mucosa samples from 35 chronic, nonatrophic gastritis (CG) patients, 41 atrophic gastritis patients, 44 intestinal metaplasia with atypical hyperplasia (IM) patients, and 28 gastric carcinoma (Ca) patients. The expression of  TRAF1, 4-1BB, and Bcl-xL was determined using western blotting. The expression of cagA, vacAs1, and vacAm1 in H. pylori was examined with polymerase chain reaction. Results. The expression of TRAF1, 4-1BB, and Bcl-xL was significantly upregulated in IM and Ca patients (P < 0.05 compared with CG). There were more cases of cagA+/vacAs1+/vacAm1+ H. pylori infection in samples with elevated TRAF1, 4-1BB, or Bcl-xL expression (P < 0.05). Additionally, there were a remarkably large number of samples with upregulated TRAF1/4-1BB/Bcl-xL expression in cases of cagA+/vacAs1+/vacAm1+ H. pylori infection (44 cases, 67.7%; P < 0.05). Conclusions. The pathogenesis of IM and Ca may be promoted by cagA+/vacAs1+/vacAm1+ H. pylori, possibly via upregulated TRAF1, 4-1BB, and Bcl-xL in gastric mucosal tissue.

Histopathological determinants of tumor resistance: a special look to the immunohistochemical expression of carbonic anhydrase IX in human cancers

Intrinsic and acquired drug resistance of tumor cells still causes the failure of treatment regimens in advanced human cancers. It may be driven by intrinsic tumor cells features, or may also arise from micro environmental influences. Hypoxia is a microenvironment feature associated with the aggressiveness and metastasizing ability of human solid cancers. Hypoxic cancer cells overexpress Carbonic Anhydrase IX (CA IX). CA IX ensures a favorable tumor intracellular pH, while contributing to stromal acidosis, which facilitates tumor invasion and metastasis. The overexpression of CA IX is considered an epiphenomenon of the presence of hypoxic, aggressive tumor cells. Recently, a relationship between CA IX overexpression and the cancer stem cells (CSCs) population has been hypothesized. CSCs are strictly regulated by tumor hypoxia and drive a major non-mutational mechanism of cancer drug-resistance. We reviewed the current data concerning the role of CA IX overexpression in human malignancies, extending such information to the expression of the stem cells markers CD44 and nestin in solid cancers, to explore their relationship with the biological behavior of tumors. CA IX is heavily expressed in advanced tumors. A positive trend of correlation between CA IX overexpression, tumor stage/grade and poor outcome emerged. Moreover, stromal CA IX expression was associated with adverse events occurrence, maybe signaling the direct action of CA IX in directing the mesenchymal changes that favor tumor invasion; in addition, membranous/cytoplasmic co-overexpression of CA IX and stem cells markers were found in several aggressive tumors. This suggests that CA IX targeting could indirectly deplete CSCs and counteract resistance of solid cancers in the clinical setting.

Deconstructing breast cancer cell biology and the mechanisms of multidrug resistance

Cancer complexity constantly challenges the way that clinicians manage breast cancer therapy. Tumor heterogeneity and intratumoral stroma characteristics allow cells with different phenotypes and deregulated apoptotic, proliferative and migration abilities to co-exist contributing to a disappointing therapeutic response. While new approaches are being associated with conventional chemotherapy, such as hormonal therapy or target monoclonal antibodies, recurrence and metastasization are still observed. Membrane transporters are the cell's first line of contact with anticancer drugs having a major role in multidrug resistance events. This structural-based activity enables the cell to be drug-resistant by decreasing drug intracellular concentration through an efflux-transport mechanism, mainly associated with overexpression of ATP-binding cassette (ABC) proteins. This review focuses on some of the important structural and biological properties of the malignant cell and tumor microenvironment, addressing the role of the membrane ABC transporters in therapeutic outcomes, and highlighting related molecular pathways that may represent meaningful target therapies.

ABCB5 is a limbal stem cell gene required for corneal development and repair

Corneal epithelial homeostasis and regeneration are sustained by limbal stem cells (LSCs), and LSC deficiency is a major cause of blindness worldwide. Transplantation is often the only therapeutic option available to patients with LSC deficiency. However, while transplant success depends foremost on LSC frequency within grafts, a gene allowing for prospective LSC enrichment has not been identified so far. Here we show that ATP-binding cassette, sub-family B, member 5 (ABCB5) marks LSCs and is required for LSC maintenance, corneal development and repair. Furthermore, we demonstrate that prospectively isolated human or murine ABCB5-positive LSCs possess the exclusive capacity to fully restore the cornea upon grafting to LSC-deficient mice in xenogeneic or syngeneic transplantation models. ABCB5 is preferentially expressed on label-retaining LSCs in mice and p63α-positive LSCs in humans. Consistent with these findings, ABCB5-positive LSC frequency is reduced in LSC-deficient patients. Abcb5 loss of function in Abcb5 knockout mice causes depletion of quiescent LSCs due to enhanced proliferation and apoptosis, and results in defective corneal differentiation and wound healing. Our results from gene knockout studies, LSC tracing and transplantation models, as well as phenotypic and functional analyses of human biopsy specimens, provide converging lines of evidence that ABCB5 identifies mammalian LSCs. Identification and prospective isolation of molecularly defined LSCs with essential functions in corneal development and repair has important implications for the treatment of corneal disease, particularly corneal blindness due to LSC deficiency.

P-glycoprotein associates with Anxa2 and promotes invasion in multidrug resistant breast cancer cells

Several recent studies have suggested that the acquisition of the multidrug resistance (MDR) phenotype is associated with elevated invasion and metastasis of tumor cells. P-glycoprotein (P-gp), the major determinant in the generation of the MDR phenotype, was reported to be correlated with a more aggressive phenotype and poor prognosis in many forms of malignancies. However, a clear understanding of the association is still lacking. We previously showed that Anxa2, a calcium-dependent phospholipid-binding protein, interacts with P-gp and contributes to the invasiveness of MDR breast cancer cells. In the present study, a strong positive correlation between MDR1 and Anxa2 mRNA expression in invasive breast cancer tissues during cancer progression was observed. In addition, exposure to adriamycin significantly enhanced motility in breast cancer cells and increased levels of P-gp and Anxa2. Moreover, inhibition of P-gp activity, using selective P-gp modulators, was found to significantly inhibit the invasive capacity of MCF-7/ADR cells without affecting the interaction and co-localization between P-gp and Anxa2. However, suppression of P-gp pump activity and knockdown of MDR1 expression both disrupted adriamycin-induced Anxa2 phosphorylation. Interestingly, P-gp was further demonstrated to interact with Src, a tyrosine kinase upstream of Anxa2. Taken together, our results indicate that P-gp may promote the invasion of MDR breast cancer cells by modulating the tyrosine phosphorylation of Anxa2. The interaction between Anxa2 and P-gp is possibly, at least in part, responsible for the association between MDR and invasive potential in breast cancer cells.

Association between single genetic polymorphisms of MDR1 gene and gastric cancer susceptibility in Chinese

Gastric cancer is a common cancer worldwide. The multidrug resistance 1 gene (MDR1) is one of the most important candidate genes for influencing gastric cancer susceptibility. This study aimed to analyze the association between genetic variants of MDR1 gene and the susceptibility to gastric cancer in Chinese Han population. A total of 365 gastric cancer patients and 367 cancer-free controls were enrolled in this study. The single genetic polymorphisms (SNPs) of MDR1 gene were genotyped by the created restriction site-polymerase chain reaction method. Our data suggested that the allele and genotype frequencies of c.159G > T and c.1564A > T were statistically different between gastric cancer patients and cancer-free controls. Association analyses indicated that these two SNPs were statistically associated with the increased risk of gastric cancer (for c.159G > T, TT versus (vs.) GG: OR 2.34, 95 % CI 1.31-4.19; TT vs.

GT/GG

OR 2.32, 95 % CI 1.32-4.08; T vs. G: OR 1.27, 95 % CI 1.01-1.59; for c.1564A > T, TT vs. AA: OR 2.27, 95 % CI 1.31-3.93; TT vs.

AT/AA

OR 2.21, 95 % CI 1.30-3.75; T vs. A: OR 1.30, 95 % CI 1.04-1.62). The allele-T of both these two SNPs may contribute to the susceptibility to gastric cancer in Chinese Han population. The c.159G > T and c.1564A > T genetic variants might be used as molecular markers for detecting gastric cancer susceptibility.

A cancer-specific variant of the SLCO1B3 gene encodes a novel human organic anion transporting polypeptide 1B3 (OATP1B3) localized mainly in the cytoplasm of colon and pancreatic cancer cells

OATP1B3 is a member of the OATP (organic anion transporting polypeptides) superfamily, responsible for mediating the transport of numerous endogenous and xenobiotic substances. Although initially reported to be exclusively expressed in the liver, several studies reported that OATP1B3 is frequently expressed in multiple types of cancers and may be associated with differing clinical outcomes. However, a detailed investigation on the expression and function of OATP1B3 protein in cancer has been lacking. In this study, we confirmed that colon and pancreatic cancer cells express variant forms of OATP1B3, different from OATP1B3 wild-type (WT) expressed in the normal liver. OATP1B3 variant 1 (V1), the most prevalent form among the variants, contains alternative exonic sequences (exon 2a) instead of exons 1 and 2 present in OATP1B3 WT. The translated product of OATP1B3 V1 is almost identical to OATP1B3 WT, with exception to the first 28 amino acids at the N-terminus. Exogenous expression of OATP1B3 V1 revealed that OATP1B3 V1 undergoes post-translational modifications and proteasomal degradation to a differing extent compared to OATP1B3 WT. OATP1B3 V1 showed only modest transport activity toward cholecystokin-8 (CCK-8, a prototype OATP1B3 substrate) in contrast to OATP1B3 WT showing a markedly efficient uptake of CCK-8. Consistent with these results, OATP1B3 V1 was localized mainly in the cytoplasm with a much lower extent of trafficking to the surface membrane compared to OATP1B3 WT. In summary, our results demonstrate that colon and pancreatic cancer cells express variant forms of OATP1B3 with only limited transport activity and different subcellular localization compared to OATP1B3 WT. These observed differences at the molecular and functional levels will be important considerations for further investigations of the biological and clinical significance of OATP1B3 expression in cancer.