Expression Of Drug Resistance Genes Research Articles

Triclosan treatment decreased the antitumor effect of sorafenib on hepatocellular carcinoma cells.

BackgroundTriclosan is a widely applied antimicrobial agent which affects the endocrine system and homeostasis; it may also promote the cirrhosis and hepatocellular carcinoma (HCC) growth in a mice model. The exact roles of triclosan in regulating human hepatocellular carcinoma development and treatment remain unknown.MethodsMHCC97-H, a highly aggressive HCC cell line, was treated with indicated concentration of triclosan or sorafenib. The expression of drug-resistance genes was examined by qPCR. The clearance or metabolism of sorafenib was determined by liquid chromatograph-mass spectrometer/mass spectrometer (LC-MS/MS). MTT assay was used to examine the MHCC97-H cell proliferation. Nude mice were used to exam the anti-tumor effect of sorafenib on subcutaneous and intrahepatic growth of MHCC97-H cells.ResultsIn the present study, triclosan could induce the expression of drug-resistance genes in MHCC97-H cells (a highly aggressive HCC cell line), accelerate the clearance of sorafenib, and attenuate the anti-proliferation effect of this molecular targeted agent in MHCC97-H cells. Triclosan decreased the antitumor effect of sorafenib on subcutaneous and intrahepatic growth of MHCC97-H in nude mice.ConclusionBy discovering the fact that triclosan treatment enhances sorafenib resistance in HCC cells, this work suggests exposure of triclosan is detrimental to HCC patients during chemotherapy.

The reversal effect of Ginsenoside Rh2 on drug resistance in human colorectal carcinoma cells and its mechanism.

Recent studies hint that Ginsenoside is involved in cancer prevention and treatment. In this study, we investigated the effect of Ginsenoside Rh2 ondrug resistanceinhumancolorectalcarcinoma (CRC)cells and its mechanism. The resistance reversion effect of Ginsenoside Rh2 in CRC cells was analyzed using CCK-8 assay. After treating with Ginsenoside Rh2, the cell cycle distribution and cellular apoptosis were analyzed by flow cytometry, cell migration was determined by transwell migration assay, the expression of drug-resistance genes and proteins were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot, respectively. Ginsenoside Rh2 could enhance the cytotoxicity of 5-FU in drug-resistant CRC cells (LoVo/5-FU and HCT-8/5-FU). Treatment with Ginsenoside Rh2 could result in an increase of cell numbers in G0/G1 phase accompanied with a decrease in S-phase, and induced cellular apoptosis in drug-resistant CRC cells. In addition, the migration process and EMT process of drug-resistant CRC cells were suppressed by treatment of Ginsenoside Rh2. Compared to control group, expression of drug-resistance genes, such as MRP1, MDR1, LRP and GST, were negatively correlated to Ginsenoside Rh2. All these results indicated that Ginsenoside Rh2 could effectively reverse drug resistancein humancolorectalcarcinoma cell and its mechanism involved the prevention of cellular proliferation and migration, the promotion of cellular apoptosis and the alteration of drug-resistance genes, which suggested that Ginsenoside Rh2 may act as a promising candidate for drug resistance in humancolorectalcarcinoma chemotherapy.

Co-targeting of Tiam1/Rac1 and Notch ameliorates chemoresistance against doxorubicin in a biomimetic 3D lymphoma model.

Lymphoma is a heterogeneous disease with a highly variable clinical course and prognosis. Improving the prognosis for patients with relapsed and treatment-resistant lymphoma remains challenging. Current in vitro drug testing models based on 2D cell culture lack natural tissue-like structural organization and result in disappointing clinical outcomes. The development of efficient drug testing models using 3D cell culture that more accurately reflects in vivo behaviors is vital. Our aim was to establish an in vitro 3D lymphoma model that can imitate the in vivo 3D lymphoma microenvironment. Using this model, we explored strategies to enhance chemosensitivity to doxorubicin, an important chemotherapeutic drug widely used for the treatment of hematological malignancies. Lymphoma cells grown in this model exhibited excellent biomimetic properties compared to conventional 2D culture including (1) enhanced chemotherapy resistance, (2) suppressed rate of apoptosis, (3) upregulated expression of drug resistance genes (MDR1, MRP1, BCRP and HIF-1α), (4) elevated levels of tumor aggressiveness factors including Notch (Notch-1, -2, -3, and -4) and its downstream molecules (Hes-1 and Hey-1), VEGF and MMPs (MMP-2 and MMP-9), and (5) enrichment of a lymphoma stem cell population. Tiam1, a potential biomarker of tumor progression, metastasis, and chemoresistance, was activated in our 3D lymphoma model. Remarkably, we identified two synergistic therapeutic oncotargets, Tiam1 and Notch, as a strategy to combat resistance against doxorubicin in EL4 T and A20 B lymphoma. Therefore, our data suggest that our 3D lymphoma model is a promising in vitro research platform for studying lymphoma biology and therapeutic approaches.

In vitro characterization of CD133lo cancer stem cells in Retinoblastoma Y79 cell line

BackgroundRetinoblastoma (Rb), the most common childhood intraocular malignant tumor, is reported to have cancer stem cells (CSCs) similar to other tumors. Our previous investigation in primary tumors identified the small sized cells with low CD133 (Prominin-1) and high CD44 (Hyaluronic acid receptor) expression to be putative Rb CSCs using flow cytometry (FSClo/SSClo/CD133lo/CD44hi). With this preliminary data, we have now utilized a comprehensive approach of in vitro characterization of Y79 Rb cell line following CSC enrichment using CD133 surface marker and subsequent validation to confirm the functional properties of CSCs.MethodsThe cultured Rb Y79 cells were evaluated for surface markers by flow cytometry and CD133 sorted cells (CD133lo/CD133hi) were compared for CSC characteristics by size/percentage, cell cycle assay, colony formation assay, differentiation, Matrigel transwell invasion assay, cytotoxicity assay, gene expression using microarray and validation by semi-quantitative PCR.ResultsRb Y79 cell line shared the profile (CD133, CD90, CXCR4 and ABCB1) of primary tumors except for CD44 expression. The CD133lo cells (16.1 ± 0.2%) were FSClo/SSClo, predominantly within the G0/G1 phase, formed larger and higher number of colonies with ability to differentiate to CD133hi cells, exhibited increased invasive potential in a matrigel transwell assay (p < 0.05) and were resistant to Carboplatin treatment (p < 0.001) as compared to CD133hi cells. The CD133lo cells showed higher expression of several embryonic stem cell genes (HOXB2, HOXA9, SALL1, NANOG, OCT4, LEFTY), stem cells/progenitor genes (MSI2, BMI1, PROX1, ABCB1, ABCB5, ABCG2), and metastasis related gene- MACC1, when compared to the CD133hi cells.ConclusionsThis study validates the observation from our earlier primary tumor study that CSC properties in Rb Y79 cell line are endowed within the CD133lo population, evident by their characteristics- i.e. small sized, dormant in nature, increased colony forming ability, differentiation to CD133hi cells, higher invasiveness potential, drug resistance and primitive gene expression pattern. These findings provide a proof of concept for methodological characterization of the retinoblastoma CSCs with future implications for improved diagnostic and treatment strategies.

Ursolic acid enhances the therapeutic effects of oxaliplatin in colorectal cancer by inhibition of drug resistance

It has been reported that ursolic acid has anti‐tumor activity and it enhances the therapeutic effect of oxaliplatin in colorectal cancer (CRC). However, the underlying mechanisms remain unknown. In the present study, the mechanisms of the enhancement of therapeutic effects through use of ursolic acid were investigated. We treated CRC cell lines HCT8 and SW480 with ursolic acid and oxaliplatin and monitored the effects on cell proliferation, apoptosis, reactive oxygen species (ROS) production and drug resistance gene production. We discovered that treatment with a combination of ursolic acid and oxaliplatin resulted in significant inhibition of cell proliferation, significantly increased apoptosis and ROS production, and significant inhibition of drug resistance gene expression. Our study provided evidence that ursolic acid enhances the therapeutic effects of oxaliplatin in colorectal cancer by ROS‐mediated inhibition of drug resistance.

ExVivo Selection of Transduced Hematopoietic Stem Cells for Gene Therapy of β-Hemoglobinopathies.

Although gene transfer to hematopoietic stem cells (HSCs) has shown therapeutic efficacy in recent trials for several individuals with inherited disorders, transduction incompleteness of the HSC population remains a hurdle to yield a cure for all patients with reasonably low integrated vector numbers. In previous attempts at HSC selection, massive loss of transduced HSCs, contamination with non-transduced cells, or lack of applicability to large cell populations has rendered the procedures out of reach for human applications. Here, we fused codon-optimized puromycin N-acetyltransferase to herpes simplex virus thymidine kinase. When expressed from a ubiquitous promoter within a complex lentiviral vector comprising the βAT87Q-globin gene, viral titers and therapeutic gene expression were maintained at effective levels. Complete selection and preservation of transduced HSCs were achieved after brief exposure to puromycin in the presence of MDR1 blocking agents, suggesting the procedure’s suitability for human clinical applications while affording the additional safety of conditional suicide.

Identification of drug-resistance related genes in natural killer/T cell lymphoma through digital gene expression and RNA-sequencing

Objective To explore the differentially expressed genes among normal natural killer (NK) cell and NK/T cell lymphoma cell lines YTS and SNK-6 and define the expression of common drug-resistance related genes in NK/T cell lymphoma cell lines. Methods The digital gene expression (DGE) profiles of normal NK cells and NK/T-cell lymphoma cells YTS and SNK-6 were detected by DGE sequencing technology. The differential expressed genes among the three cell lines were also analyzed.3 184 genes were upregulated and 2 764 genes were downregulated in SNK-6 cells as compared with normal NK cells.3 978 genes were upregulated and 2 172 genes were downregulated in YTS cells as compared with normal NK cells. However, as compared with YTS cells, 1 068 genes were upregulated and 2 425 genes were downregulated in SNK-6 cells. The expression levels of common drug-resistance related genes were examined by real-time fluorescent quantitative polymerase chain reaction (FQ-PCR). Consequently, the DGE profiles of normal NK cells and two NK/T cell lymphoma cell lines were established. Results DGE libraries of one normal NK cell line and two NK/T cell lymphoma cell lines were established and significantly differentially expressed genes of three cell lines were screened. The level of multidrug resistance protein 5 (ABCC5) mRNA was significantly higher in both YTS cells (3.69±0.11, P=0.001) and SNK-6 cells (5.22±1.66, P=0.048) than in normal NK cells (1.00±0.00). The level of erythroblastic leukemia viral oncogene homolog 4 (ERBB4) mRNA was significantly higher in both YTS cells (6.87±0.56, P=0.003) and SNK-6 cells (14.79±1.84, P=0.006) than in normal NK cells (1.00±0.00). Conclusion The highly expressed ABCC5 and ERBB4 may be associated with drug resistance in NK/T cell lymphoma. We can foresee that drug-resistance related genes might be targets for detection and treatment of NK/T cell lymphoma patients. Key words: Drug resistance genes; Digital gene expression; Natural killer/T cell lymphoma

Physiological and molecular responses of resistant and susceptible wheat cultivars to Fusarium graminearum mycotoxin extract

Fusarium graminearum, causing Fusarium head blight (FHB), is one of the most important diseases on cereals worldwide leading to a reduction in both grain yield and quality. Currently, there is limited knowledge about the physiological and molecular mechanisms involved in wheat resistance against F. graminearum mycotoxins. Crude culture extract of F. graminearum was used to determine the physiological and molecular responses of wheat cultivars ‘Falat’ and ‘Sumai3‘, susceptible and resistant to FHB, respectively. Point inoculation of crude extract in the wheat spikelets resulted in significant increases in hydrogen peroxide (H2O2) and malondialdehyde (MDA) content in both cultivars, most likely due to oxidative stress. A greater induction level and activity of H2O2, MDA, peroxidase (POX), phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) was observed in the resistant versus the susceptible cultivar. In addition, quantitative real-time PCR indicated earlier and greater induction of PAL, pleiotropic drug resistance (PDR) and cytochrome P450 (CYP) gene expression in ‘Sumai3‘ compared with ‘Falat’. Responses associated with the resistant interaction in ‘Sumai3‘ were higher induction of superoxide dismutase (SOD) and POX and decreased activity of catalase, while decreased SOD activity was observed in ‘Falat’. Our data suggest that these responses could explain the higher degree of tolerance of ‘Sumai3‘ against F. graminearum.

Characterization of cancer stem cell drug resistance in the human colorectal cancer cell lines HCT116 and SW480

BackgroundCancer stem cells (CSCs) share a number of properties with somatic stem cells including heightened protective mechanisms and the ability to self-renew. CSCs are a critical subpopulation of cancer cells implicated in tumor formation, metastases and recurrence. MethodsWe used serial colonosphere culture to enrich for CSCs from two human CRC cell lines. The expression of proposed colorectal CSC markers and multi-drug resistance genes were assessed via flow cytometry and RT-qPCR. Drug resistance gene expression and self-renewal ability were also determined following treatment with the chemotherapeutic 5-fluorouracil. ResultsColonosphere culture successfully enriched for a subpopulation of cells with CSC-related gene expression and heightened self-renewal ability, particularly in the SW480 cell line. Chemotherapy treatment significantly reduced sphere formation however a small fraction of cells survived treatment and retained their self-renewal ability. ConclusionsOur findings support the use of the sphere formation assay to study CSCs. The ability of cells to self-renew following chemotherapy treatment highlights the importance of targeting both the bulk of tumor cells and the CSC population to prevent recurrence in colorectal cancer.

Analysis of Shigella flexneri Resistance, Biofilm Formation, and Transcriptional Profile in Response to Bile Salts.

The Shigella species cause millions of cases of watery or bloody diarrhea each year, mostly in children in developing countries. While many aspects of Shigella colonic cell invasion are known, crucial gaps in knowledge regarding how the bacteria survive, transit, and regulate gene expression prior to infection remain. In this study, we define mechanisms of resistance to bile salts and build on previous research highlighting induced virulence in Shigella flexneri strain 2457T following exposure to bile salts. Typical growth patterns were observed within the physiological range of bile salts; however, growth was inhibited at higher concentrations. Interestingly, extended periods of exposure to bile salts led to biofilm formation, a conserved phenotype that we observed among members of the Enterobacteriaceae Characterization of S. flexneri 2457T biofilms determined that both bile salts and glucose were required for formation, dispersion was dependent upon bile salts depletion, and recovered bacteria displayed induced adherence to HT-29 cells. RNA-sequencing analysis verified an important bile salt transcriptional profile in S. flexneri 2457T, including induced drug resistance and virulence gene expression. Finally, functional mutagenesis identified the importance of the AcrAB efflux pump and lipopolysaccharide O-antigen synthesis for bile salt resistance. Our data demonstrate that S. flexneri 2457T employs multiple mechanisms to survive exposure to bile salts, which may have important implications for multidrug resistance. Furthermore, our work confirms that bile salts are important physiological signals to activate S. flexneri 2457T virulence. This work provides insights into how exposure to bile likely regulates Shigella survival and virulence during host transit and subsequent colonic infection.

Circadian Gene CLOCK Affects Drug-Resistant Gene Expression and Cell Proliferation in Ovarian Cancer SKOV3/DDP Cell Lines Through Autophagy.

Abnormal autophagy regulation affects the chemoresistance of ovarian cancer, during which the circadian gene clock may play a major role. In this study, RNA interference plasmid pSUPER-Clock and overexpression plasmid pcDNA3.1-Clock of CLOCK were used to stably transfect the SKOV3/DDP cells by lipofection. Upon screening, the in vitro transfected cell lines with pSUPER-Clock, the autophagy level, and G0/G1 phase cells were significantly reduced, and the expression levels of Clock, LC3, P-gp, and MRP2 were inhibited. In contrast, the autophagy level and G0/G1 phase cells in cell lines transfected with pcDNA3.1-Clock were significantly increased, and the expressions of Clock, LC3, P-gp, and MRP2 were enhanced. In comparison with the untransfected control group showed the percentage of apoptotic cells in SKOV3/DDP cell lines of Clock interfering expression group after cisplatin treatment was significantly increased while the survival was substantially reduced. These results indicated that inhibiting the circadian gene Clock expression can reverse the cisplatin resistance of ovarian cancer SKOV3/DDP cell lines by affecting the protein expression of drug resistance genes during which autophagy plays an important role. The CLOCK gene may be designated as a novel candidate for targeted gene therapy in drug-resistant ovarian cancer.

Acinetobacterbaumannii quorum-sensing signalling molecule induces the expression of drug-resistance genes.

Quorum-sensing signalling molecules such as N-acyl homoserine lactones (AHLs) enable certain Gram-negative bacteria to respond to environmental changes through behaviours, such as biofilm formation and flagellar movement. The present study aimed to identify Acinetobacter baumannii AHLs and assess their influence on antibiotic resistance. A clinical isolate of A. baumannii strain S (AbS) was collected from the wound of a burn patient and high-performance liquid chromatography and tandem quadrupole or quadrupole time-of-flight high-resolution mass spectrometry was used to identify AbS AHLs. Antibiotic sensitivity was assessed in an AHL-deficient AbS mutant (AbS-M), and the expression of drug-resistance genes in the presence of meropenem in AbS, AbS-M and AbS-M treated with the AHL N-3-hydroxy-dodecanoyl-homoserine lactone (N-3-OH-C12-HSL). AbS-M was more sensitive to meropenem and piperacillin than wild-type AbS, but resistance was restored by supplementation with N-3-OH-C12-HSL. In addition, meropenem-treated AbS-M expressed lower levels of the drug-resistance genes oxacillinase 51, AmpC, AdeA and AdeB; treatment with N-3-OH-C12-HSL also restored the expression of these genes. Overall, the results of the present study indicate that N-3-OH-C12-HSL may be involved in regulating the expression of drug-resistance genes in A. baumannii. Therefore, this quorum-sensing signalling molecule may be an important target for treating multidrug-resistant A. baumannii infections.

Growth of tyrosine kinase inhibitor-resistant Philadelphia-positive acute lymphoblastic leukemia: Role of bone marrow stromal cells.

Human bone marrow stromal cells (hBMSCs) may contribute to the growth of tyrosine kinase inhibitor (TKI)-resistant chronic myelogenous leukemia (CML). However, there are certain differences in biology between CML and Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL). Little is known about the role and mechanism of hBMSCs on the growth of TKI-resistant Ph+ ALL. The current study co-cultured hBMSCs with the TKI-resistant SUP-B15. Next, the proliferation of SUP-B15 was detected using a Cell Counting Kit-8. Additionally, quantitative polymerase chain reaction and flow cytometry were used to detect the expression of the associated genes and proteins. The present study explores the role and mechanism of hBMSCs on the growth of TKI-resistant Ph+ ALL. The current study showed that hBMSCs promoted the proliferation of TKI-resistant Ph+ ALL. This was shown by the increase in cells in the S+G2-M phase of the cell cycle. It was also found that the expression of cyclins A, C, D1 and E was increased. Apoptosis was inhibited through upregulation of anti-apoptotic genes [B-cell lymphoma-2 (BCL-2) and BCL-extra large] and downregulation of apoptotic genes (BCL-XS, BCL-2-associated X protein, and caspases 3, 7 and 9). Expression of the breakpoint cluster region (BCR)-Abelson murine leukemia viral oncogene homolog 1 (ABL) gene, Wnt5a, and Wnt signaling pathway-associated genes (glycogen synthase kinase-3β, β-catenin, E-cadherin and phosphoinositide 3-kinase) and transcription factors (c-myc, ephrin type-B2, fibroblast growth factor 20 and matrix metalloproteinase 7) was also increased. Furthermore, the expression of drug resistance genes (low-density lipoprotein receptor, multidrug resistance-associated protein and multi-drug resistance gene) was increased and the expression of anti-oncogenes (death-associated protein kinase and interferon regulatory factor-1) was decreased. It was concluded that hBMSCs promote the growth of TKI-resistant Ph+ ALL by these aforementioned mechanisms. Therefore, targeting hBMSCs may be a promising approach for preventing the growth of TKI-resistant Ph+ ALL.

The effect of S1P receptor signaling pathway on the survival and drug resistance in multiple myeloma cells

Multiple myeloma (MM) remains incurable by conventional chemotherapy. Sphingosine-1-phosphate (S1P) receptor-mediated signaling has been recently demonstrated to have critical roles in cell survival and drug resistance in a number of hematological malignancies. To dissect the roles of S1P receptor pathway in MM, we systematically examined cell viability and protein expression associated with cell survival and drug resistance in MM cell lines upon treatment with either pathway activator (S1P) or inhibitor (FTY720). Our results reveal that FTY720 inhibits cell proliferation by downregulating expression of target genes, while S1P has an opposite effect. Knocking down of S1P receptor S1P5R results in a reduction of cell survival-related gene expression; however, it does not have impacts on expression of drug resistance genes. These results suggest that S1P signaling plays a role in cell proliferation and drug resistance in MM, and targeting this pathway will provide a new therapeutic direction for MM management.

Application of optically-induced-dielectrophoresis in microfluidic system for purification of circulating tumour cells for gene expression analysis- Cancer cell line model.

Circulating tumour cells (CTCs) in a blood circulation system are associated with cancer metastasis. The analysis of the drug-resistance gene expression of cancer patients’ CTCs holds promise for selecting a more effective therapeutic regimen for an individual patient. However, the current CTC isolation schemes might not be able to harvest CTCs with sufficiently high purity for such applications. To address this issue, this study proposed to integrate the techniques of optically induced dielectrophoretic (ODEP) force-based cell manipulation and fluorescent microscopic imaging in a microfluidic system to further purify CTCs after the conventional CTC isolation methods. In this study, the microfluidic system was developed, and its optimal operating conditions and performance for CTC isolation were evaluated. The results revealed that the presented system was able to isolate CTCs with cell purity as high as 100%, beyond what is possible using the previously existing techniques. In the analysis of CTC gene expression, therefore, this method could exclude the interference of leukocytes in a cell sample and accordingly contribute to higher analytical sensitivity, as demonstrated in this study. Overall, this study has presented an ODEP-based microfluidic system capable of simply and effectively isolating a specific cell species from a cell mixture.

Abstract 306: Analysis of differentially expressed exosomal genes from ibrutinib resistant diffuse large B cell lymphoma

Abstract Diffuse large B cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL) and approximately 30% of the patients develop relapsed/refractory disease that becomes a major cause of mortality and morbidity. Selective pressure provided by chemotherapy causes aberrant gene expression and selection of pre-existing population of chemo-resistant cells. These chemo-resistant cells can also transmit chemo-resistance to chemo-sensitive cells through exosomal transfer of molecules (miRNA, mRNA and proteins). In this study, we have analysed differentially expressed mRNA and miRNA from syngeneic ibrutinib (an irreversible BTK inhibitor, FDA approved) resistant DLBCL cells and from their isolated exosomes. Five DLBCL-GCB and five ABC subtype were analysed for their sensitivity with ibrutinib. We found three ABC subtype and one GCB subtype (OCL-LY1) were sensitive to ibrutinib. We have generated syngeneic ibrutinib drug resistant model from sensitive cells (at least 10 fold increase in IC50 value) by continuous culturing them in the presence of ibrutinib with gradual increase in drug concentration in each passage. Ibrutinib sensitive DLBCL cells when cultured with the syngeneic resistant cells in transwell apparatus, acquired resistance to ibrutinib. We also analysed the sensitivity of ibrutinib resistant cells with other conventional drugs for non-Hodgkin lymphomas. We further tested the expression of drug resistant genes in syngeneic resistant cells by real time PCR analysis. Later, we isolated the total RNA and miRNA species from DLBCL ibrutinib sensitive, their syngeneic resistant cells and from respective exosomes and analysed for differential expression by micro array analyses. Thus in conclusion, our study demonstrates that chemo-resistance can be transferred from resistant cells to sensitive cells via exosomal horizontal transmission of miRNA and mRNA in diffuse large B cell lymphoma cells. Moreover, our study identified potential targets that can be used to overcome chemo-resistance in diffuse large B cell lymphoma. Citation Format: Neeraj Jain, Lalit Sehgal, Tamer Khashab, Felipe Samaniego. Analysis of differentially expressed exosomal genes from ibrutinib resistant diffuse large B cell lymphoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 306.

Abstract 169: Drug resistance gene expression pathways in primary refractory breast cancer

Abstract Purpose/Objective: Breast cancer is a collection of diseases with distinct molecular subtypes with differing prognoses. Clinically, there is a group of therapy resistant breast cancers characterized by resistance to conventional chemo- and radiotherapy with short overall survival and poor prognosis, which we termed primary refractory breast cancer (PRBC). We hypothesized that PRBC is characterized by specific genomic changes that may contribute to therapy resistance. The aim of this study was to identify changes in gene expression profiles of PRBC compared to triple negative (TNBC) and ER+/-PR positive (HR) breast cancer cohorts. Methods: PRBC was defined as patients with an initial diagnosis of Stage I-III breast cancer who either I) developed metastatic disease within 6 months of completing treatment or II) died of breast cancer within two years of initial diagnosis. Formalin-fixed paraffin-embedded (FFPE) tissue was obtained under an IRB approved protocol 01-13-43c. RNA was extracted from macro-dissected FFPE tumor tissue. Gene expression profiling was performed with Affymetrix Human Transcriptome Array 2.0 and gene signatures were analyzed using a single sample gene set enrichment methodology. Gene signatures of PRBC patients were compared to signatures of two TNBC and HR cohorts with gene expression data generated by identical methodology. Results: A total of nineteen samples from eight patients had sufficient tumor material to obtain RNA. The median age at diagnosis was 44.3 years, 62.5% were triple negative. At initial diagnosis the stage ranged from IA to IIIC. Sixty-three percent received neoadjuvant chemotherapy. The median time to relapse was 8.4 months and median time to death 1.7 years. Genomic analysis identified highly significant (p&amp;lt;10-6) increased expression of ABC transporters, hypoxia, interferon, DNA repair and AKT signatures compared to control cohorts. Conclusions: PRBC is characterized by significant upregulation of multiple gene expression signatures important in drug resistance including ABC transporters, hypoxia, AKT and DNA repair pathways. Confirmation of these results would allow the development of alternative treatment strategies for PRBC to help improve the devastatingly poor prognosis of this subgroup of patients. Citation Format: Charlene Kan, Shikha Parsai, Stefanie Avril, Janice Lyons, Hannah Gilmore, Junran Zhang, Lyndsay Harris. Drug resistance gene expression pathways in primary refractory breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 169.

The calcineruin inhibitor cyclosporine a synergistically enhances the susceptibility of Candida albicans biofilms to fluconazole by multiple mechanisms.

BackgroundBiofilms produced by Candida albicans (C. albicans) are intrinsically resistant to fungicidal agents, which are a main cause of the pathogenesis of catheter infections. Several lines of evidence have demonstrated that calcineurin inhibitor FK506 or cyclosporine A (CsA) can remarkably enhance the antifungal activity of fluconazole (FLC) against biofilm-producing C. albicans strain infections. The aim of present study is thus to interrogate the mechanism underpinning the synergistic effect of FLC and calcineurin inhibitors.ResultsTwenty four clinical C. albicans strains isolated from bloodstream showed a distinct capacity of biofilm formation. A combination of calcineurin inhibitor CsA and FLC exhibited a dose-dependent synergistic antifungal effect on the growth and biofilm formation of C. albicans isolates as determined by a XTT assay and fluorescent microscopy assay. The synergistic effect was accompanied with a significantly down-regulated expression of adhesion-related genes ALS3, hypha-related genes HWP1, ABC transporter drug-resistant genes CDR1 and MDR1, and FLC targeting gene, encoding sterol 14alpha-demethylase (ERG11) in clinical C. albicans isolates. Furthermore, an addition of CsA significantly reduced the cellular surface hydrophobicity but increased intracellular calcium concentration as determined by a flow cytometry assay (p < 0.05).ConclusionThe results presented in this report demonstrated that the synergistic effect of CsA and FLC on inhibited C. albicans biofilm formation and enhanced susceptibility to FLC was in part through a mechanism involved in suppressing the expression of biofilm related and drug-resistant genes, and reducing cellular surface hydrophobicity, as well as evoking intracellular calcium concentration.

CD24 Expression May Play a Role as a Predictive Indicator and a Modulator of Cisplatin Treatment Response in Head and Neck Squamous Cellular Carcinoma.

Platinum-based therapy is most often used to treat advanced cases of head and neck cancers, but only a small fraction of the patient population responds to cisplatin, with a median survival time of less than a year. Although gene signatures and molecular etiology of head and neck cancers have been previously described, none of them are predictive indicators of cisplatin treatment response in particular. Therefore, currently, there is a lack of clinically employable predictive indicators of the disease beyond HPV status to specifically predict patients' response to platinum-based therapy. It beckons a substantial effort to look for predictive indicators of cisplatin treatment response. In this regard, CD24 expression level appears to be a significant molecular phenotype of cisplatin-resistant residual cells in laryngeal carcinoma lines. CD24 expression level directly affects cisplatin sensitivity and affects the expression of critical apoptotic, stem and drug resistance genes. A relatively small retrospective patient tumor analysis suggests that CD24 high tumors go on to show an unfavorable response to cisplatin treatment. Overall, based on the strength of further analysis, CD24 presents a strong rationale to be utilized as a predictive indicator to stratify head and neck cancer patients for platinum-based therapy. It also provides a rationale for using CD24 as a therapeutic adjuvant target along with standard cisplatin therapy.

Knockdown of long noncoding RNA H19 sensitizes human glioma cells to temozolomide therapy.

Temozolomide (TMZ) is commonly used in glioma chemotherapy. However, a great clinical challenge for TMZ is chemoresistance. H19 transcripts are recognized as long noncoding RNAs, which potentially interact with chromatin-modifying complexes to regulate gene expression via epigenetic changes. Our data based on glioma patients showed that the expression of H19 was significantly upregulated in TMZ-resistant tumors compared with the TMZ-sensitive tumors. To determine the function of H19 in glioma, cell lines U87 and U251 were exposed to TMZ to establish TMZ-resistant clones U87TMZ and U251TMZ. In U87TMZ and U251TMZ, the expression level of H19 transcripts was increased compared to wild-type or nonresistant clones, as determined by real-time quantitative reverse transcription polymerase chain reaction. Concomitant treatment with small interfering RNA specifically targeting H19 and TMZ in resistant glioma clones resulted in decreased IC50 values for TMZ, and increased apoptotic rates than control small interfering RNA-treated cells. This was also evident by the increased PARP cleavage in resistant cells exposed to TMZ + si-H19. Furthermore, the reduced expression of H19 altered major drug resistance genes, such as MDR, MRP, and ABCG2, both at the mRNA and protein levels. Taken together, these findings suggest that H19 plays an important role in the development of TMZ resistance, and may represent a novel therapeutic target for TMZ-resistant gliomas.