Oncogenic LncRNA CASC9 in Cancer Progression

2020 ◽  
Vol 26 ◽  
Author(s):  
Yuying Qi ◽  
Chaoying Song ◽  
Jiali Zhang ◽  
Chong Guo ◽  
Chengfu Yuan
Keyword(s):  
Cell Proliferation ◽  
Drug Resistance ◽  
Cell Growth ◽  
Cancer Cells ◽  
Therapeutic Potential ◽  
Squamous Metaplasia ◽  
Neoplastic Transformation ◽  
Over Expression ◽  
Human Cancers ◽  
Current Review

Background: Long non-coding RNA (LncRNAs), with the length over 200 nucleotides, originate from intergenic, antisense, or promoter-proximal regions, is a large family of RNAs that lack coding capacity. Emerging evidences illustrated that LncRNAs played significant roles in a variety of cellular functions and biological processes in profuse human diseases, especially in cancers. Cancer susceptibility candidate 9 (CASC9), as a member of the LncRNAs group, was firstly found its oncogenic function in esophageal cancer. In following recent studies, a growing amount of human malignancies are verified to be correlated with CASC9, most of which are derived from the squamous epithelium tissue. This present review attempts to highlight the latest insights into the expression, functional roles, and molecular mechanisms of CASC9 in different human malignancies. Methods: In this review, the latest findings related to the pathophysiological processes of CASC9 in human cancers were summarized and analyzed, the associated studies were collected in systematically retrieval of PubMed used lncRNA and CASA9 as keywords. Results: CASC9 expression is identified to be aberrantly elevated in a variety of malignancies. The over-expression of CASC9 has been suggested to accelerate cell proliferation, migration, cell growth and drug resistance of cancer cells, while depress cell apoptosis, revealing its role as an oncogene. Moreover, the current review demonstrated CASC9 closely relates to neoplastic transformation of squamous epithelial cells and squamous metaplasia in non-squamous epithelial tissues. Finally, we discuss the limitations and tremendous diagnostic/therapeutic potential of CASC9 in various human cancers. Results: CASC9 expression is identified to be aberrantly elevated in a variety of malignancies. The over-expression of CASC9 has been suggested to accelerate cell proliferation, migration, cell growth and drug resistance of cancer cells, while depress cell apoptosis, revealing its role as an oncogene. Moreover, the current review demonstrated CASC9 closely relates to neoplastic transformation of squamous epithelial cells and squamous metaplasia in non-squamous epithelial tissues. Finally, we discuss the limitations and tremendous diagnostic/therapeutic potential of CASC9 in various human cancers. Conclusion: Long non-coding RNACASC9 likely served as useful disease biomarkers or therapy targets that could effectively apply in treatment of different kinds of cancers.

Knockdown CYP2S1 inhibits lung cancer cells proliferation and migration

2021 ◽  
pp. 1-9
Author(s):  
Huan Guo ◽  
Baozhen Zeng ◽  
Liqiong Wang ◽  
Chunlei Ge ◽  
Xianglin Zuo ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cell Proliferation ◽  
Cell Growth ◽  
Cancer Cells ◽  
Molecular Mechanisms ◽  
Lung Cancer Cells ◽  
Invasion And Migration ◽  
And Migration

BACKGROUND: The incidence of lung cancer in Yunnan area ranks firstly in the world and underlying molecular mechanisms of lung cancer in Yunnan region are still unclear. We screened a novel potential oncogene CYP2S1 used mRNA microassay and bioinformation database. The function of CYP2S1 in lung cancer has not been reported. OBJECTIVE: To investigate the functions of CYP2S1 in lung cancer. METHODS: Immunohistochemistry and Real-time PCR were used to verify the expression of CYP2S1. Colony formation and Transwell assays were used to determine cell proliferation, invasion and migration. Xenograft assays were used to detected cell growth in vivo. RESULTS: CYP2S1 is significantly up-regulated in lung cancer tissues and cells. Knockdown CYP2S1 in lung cancer cells resulted in decrease cell proliferation, invasion and migration in vitro. Animal experiments showed downregulation of CYP2S1 inhibited lung cancer cell growth in vivo. GSEA analysis suggested that CYP2S1 played functions by regulating E2F targets and G2M checkpoint pathway which involved in cell cycle. Kaplan-Meier analysis indicated that patients with high CYP2S1 had markedly shorter event overall survival (OS) time. CONCLUSIONS: Our data demonstrate that CYP2S1 exerts tumor suppressor function in lung cancer. The high expression of CYP2S1 is an unfavorable prognostic marker for patient survival.

scholarly journals Characterising the Response of Human Breast Cancer Cells to Polyamine Modulation

Biomolecules ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 743
Author(s):  
Oluwaseun Akinyele ◽  
Heather M. Wallace
Keyword(s):  
Breast Cancer ◽  
Cell Proliferation ◽  
Cell Growth ◽  
Cancer Cells ◽  
Cell Lines ◽  
Cancer Cell ◽  
Breast Cancer Cells ◽  
Growth Responses ◽  
Cancer Management ◽  
Mcf 7

Breast cancer is a complex heterogeneous disease with multiple underlying causes. The polyamines putrescine, spermidine, and spermine are polycationic molecules essential for cell proliferation. Their biosynthesis is upregulated in breast cancer and they contribute to disease progression. While elevated polyamines are linked to breast cancer cell proliferation, there is little evidence to suggest breast cancer cells of different hormone receptor status are equally dependent on polyamines. In this study, we characterized the responses of two breast cancer cells, ER+ (oestrogen receptor positive) MCF-7 and ER- MDA-MB-231 cell lines, to polyamine modulation and determined the requirement of each polyamine for cancer cell growth. The cells were exposed to DFMO (a polyamine pathway inhibitor) at various concentrations under different conditions, after which several growth parameters were determined. Exposure of both cell lines to DFMO induced differential growth responses, MCF-7 cells showed greater sensitivity to polyamine pathway inhibition at various DFMO concentrations than the MDA-MB-231 cells. Analysis of intracellular DFMO after withdrawal from growth medium showed residual DFMO in the cells with concomitant decreases in polyamine content, ODC protein level, and cell growth. Addition of exogenous polyamines reversed the cell growth inhibition, and this growth recovery appears to be partly dependent on the spermidine content of the cell. Similarly, DFMO exposure inhibits the global translation state of the cells, with spermidine addition reversing the inhibition of translation in the breast cancer cells. Taken together, these data suggest that breast cancer cells are differentially sensitive to the antitumour effects of polyamine depletion, thus, targeting polyamine metabolism might be therapeutically beneficial in breast cancer management based on their subtype.

Genome-Wide Methylation Analysis Identifies NOX4 and KDM5A as Key Regulators in Inhibiting Breast Cancer Cell Proliferation by Ginsenoside Rg3

2018 ◽  
Vol 46 (06) ◽  
pp. 1333-1355 ◽  
Author(s):  
Juyeon Ham ◽  
Seungyeon Lee ◽  
Hyunkyung Lee ◽  
Dawoon Jeong ◽  
Sungbin Park ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Proliferation ◽  
Cell Growth ◽  
Cancer Cells ◽  
Cancer Cell ◽  
Growth Effect ◽  
Breast Cancer Patients ◽  
Ginsenoside Rg3 ◽  
Methylation Analysis ◽  
Genome Wide

Ginsenoside Rg3 is a key metabolite of ginseng and is known to inhibit cancer cell growth. However, the epigenetics of CpG methylation and its regulatory mechanism have yet to be determined. Genome-wide methylation analysis of MCF-7 breast cancer cells treated with Rg3 was performed to identify epigenetically regulated genes and pathways. The effect of Rg3 on apoptosis and cell proliferation was examined by a colony formation assay and a dye-based cell proliferation assay. The association between methylation and gene expression was monitored by RT-PCR and Western blot analysis. Genome-wide methylation analysis identified the “cell morphology”-related pathway as the top network. Rg3 induced late stage apoptosis but inhibited cell proliferation up to 60%. Hypermethylated TRMT1L, PSMC6 and NOX4 were downregulated by Rg3, while hypomethylated ST3GAL4, RNLS and KDM5A were upregulated. In accordance, downregulation of NOX4 by siRNA abrogated the cell growth effect of Rg3, while the effect was opposite for KDM5A. Notably, breast cancer patients with a higher expression of NOX4 and KDM5A showed poor and good prognosis of survival, respectively. In conclusion, Rg3 deregulated tumor-related genes through alteration of the epigenetic methylation level leading to growth inhibition of cancer cells.

PEAK1 promotes invasion and metastasis and confers drug resistance in breast cancer

2021 ◽  
Author(s):  
xingang wang ◽  
YAN ZHENG ◽  
YU WANG
Keyword(s):  
Breast Cancer ◽  
Drug Resistance ◽  
Cell Growth ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Multi Drug Resistance ◽  
Cancer Tissues

Abstract Background and AimsPseudopodium-enriched atypical kinase 1 (PEAK1) has reported to be upregulated in human malignancies and related with poor prognosis. Enhanced PEAK1 expression facilitates tumor cell survival, invasion, metastasis and chemoresistance. However, the role of PEAK1 in breast cancer is not clear. Here, we investigated the PEAK1 expression in breast cancer and analyzed its relation with clinicopathological status and chemotherapy resistance to the neoadjuvant chemotherapy (NAC). We also investigated the role of PEAK1 on breast cancer cells in vitro and in vivo. MethodsImmunohistochemistry (IHC) was performed in 112 surgical resected breast cancer tissues. The associations between clinicopathological status, multi-drug resistance and PEAK1 expression were determined. Effect of PEAK1 overexpression or down-expression on proliferation, colony formation, invasion, migration, metastasis and Doxorubicin sensitivity in the MCF-7 cells in vitro and in vivo was detected. ResultsPEAK1 was overexpressed in breast cancer tissues and NAC -resistant breast cancer tissues. High PEAK1 expression was related with tumor size, high tumor grade, T stage, LN metastasis, recurrence, Ki-67 expression, Her-2 expression and multi-drug resistance. Targeting PEAK1 inhibited cell growth, invasion, metastasis and reversed chemoresistance to Doxorubicin in breast cancer cells in vitro and in vivo. ConclusionHigh PEAK1 expression was associated with invasion, metastasis and chemoresistance of breast cancers. Furthermore, targeting PEAK1 could inhibit cell growth and metastasis, and reverse chemoresistance in breast cancer cells, which provides an effective treatment strategies for breast cancer.

scholarly journals FXR1 regulates transcription and is required for growth of human cancer cells with TP53/FXR2 homozygous deletion

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Yichao Fan ◽  
Jiao Yue ◽  
Mengtao Xiao ◽  
Han Han-Zhang ◽  
Yao Vickie Wang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cancer Cells ◽  
Rna Binding ◽  
Cell Transformation ◽  
Human Cancer ◽  
Homozygous Deletion ◽  
Gene Promoters ◽  
Neighboring Gene ◽  
Human Cancer Cells ◽  
Human Cancers

Tumor suppressor p53 prevents cell transformation by inducing apoptosis and other responses. Homozygous TP53 deletion occurs in various types of human cancers for which no therapeutic strategies have yet been reported. TCGA database analysis shows that the TP53 homozygous deletion locus mostly exhibits co-deletion of the neighboring gene FXR2, which belongs to the Fragile X gene family. Here, we demonstrate that inhibition of the remaining family member FXR1 selectively blocks cell proliferation in human cancer cells containing homozygous deletion of both TP53 and FXR2 in a collateral lethality manner. Mechanistically, in addition to its RNA-binding function, FXR1 recruits transcription factor STAT1 or STAT3 to gene promoters at the chromatin interface and regulates transcription thus, at least partially, mediating cell proliferation. Our study anticipates that inhibition of FXR1 is a potential therapeutic approach to targeting human cancers harboring TP53 homozygous deletion.

scholarly journals The Antitumor Effect of Curcumin in Urothelial Cancer Cells Is Enhanced by Light Exposure In Vitro

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Frederik Roos ◽  
Katherina Binder ◽  
Jochen Rutz ◽  
Sebastian Maxeiner ◽  
August Bernd ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Bladder Cancer ◽  
Cell Growth ◽  
Visible Light ◽  
Cancer Cells ◽  
Cell Lines ◽  
Light Exposure ◽  
Bladder Cancer Cells

The natural compound curcumin exerts antitumor properties in vitro, but its clinical application is limited due to low bioavailability. Light exposure in skin and skin cancer cells has been shown to improve curcumin bioavailability; thus, the object of this investigation was to determine whether light exposure might also enhance curcumin efficacy in bladder cancer cell lines. RT112, UMUC3, and TCCSUP cells were preincubated with low curcumin concentrations (0.1-0.4μg/ml) and then exposed to 1.65 J/cm2visible light for 5 min. Cell growth, cell proliferation, apoptosis, cell cycle progression, and cell cycle regulating proteins along with acetylation of histone H3 and H4 were investigated. Though curcumin alone did not alter cell proliferation or apoptosis, tumor cell growth and proliferation were strongly blocked when curcumin was combined with visible light. Curcumin-light caused the bladder cancer cells to become arrested in different cell phases: G0/G1 for RT112, G2/M for TCCSUP, and G2/M- and S-phase for UMUC3. Proteins of the Cdk-cyclin axis were diminished in RT112 after application of 0.1 and 0.4μg/ml curcumin. Cell cycling proteins were upregulated in TCCSUP and UMUC3 in the presence of 0.1μg/ml curcumin-light but were partially downregulated with 0.4μg/ml curcumin. 0.4μg/ml (but not 0.1μg/ml) curcumin-light also evoked late apoptosis in TCCSUP and UMUC3 cells. H3 and H4 acetylation was found in UMUC3 cells treated with 0.4μg/ml curcumin alone or with 0.1μg/ml curcumin-light, pointing to an epigenetic mechanism. Light exposure enhanced the antitumor potential of curcumin on bladder cancer cells but by different molecular action modes in the different cell lines. Further studies are necessary to evaluate whether intravesical curcumin application, combined with visible light, might become an innovative tool in combating bladder cancer.

scholarly journals LncRNA GATA6-AS inhibits cancer cell proliferation and promotes cancer cell apoptosis in cervical cancer by down-regulating miR-205

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Xiaoying Zhao ◽  
Huzhong Zheng ◽  
Jun Chen
Keyword(s):  
Cervical Cancer ◽  
Cell Proliferation ◽  
Endothelial Cell ◽  
Cell Growth ◽  
Cancer Cell ◽  
Cell Apoptosis ◽  
Human Cancer ◽  
Over Expression ◽  
Endothelial Cell Growth ◽  
Healthy Females

Abstract Background Dysregulated endothelial cell growth is involved in many types of human cancer, including cervical cancer. LncRNA GATA6-AS was reported to regulate endothelial cell growth, suggesting it might involve in cervical cancer. Our study was carried out to explore the involvement of GATA6-AS in cervical squamous cell carcinoma (CSCC), a subtype of cervical cancer. Methods To explore the expression of GATA6-AS, RT-qPCR was performed to detect GATA6-AS in plasma of 65 CSCC patients and 58 healthy females. To detect the expression of GATA6-AS, total RNAs were extracted. Results We found that plasma GATA6-AS expression was down-regulated in CSCC patients than that in healthy females, and HPV infection did not significantly affect the plasma expression of GATA6-AS. Moreover, we found that plasma GATA6-AS showed diagnostic values for CSCC by performing ROC curve analysis. The expression of miR-205 in plasma was also found to be up-regulated in CSCC patients than that in healthy females and inversely correlated with the expression of GATA6-AS in CSCC patients. Furthermore, over-expression of miR-205 did not significantly affect the expression of GATA6-AS in CSCC cells, while over-expression of GATA6-AS down-regulated miR-205 expression. In addition, GATA6-AS over-expression inhibited CSCC cell proliferation and promoted CSCC cell apoptosis, while miR-205 over-expression played opposite roles and attenuated the effects of GATA6-AS over-expression on CSCC cells. Conclusion Taken together, these results suggest that GATA6-AS may inhibit cell proliferation and promote cell apoptosis in CSCC by down-regulating miR-205.

Combination of a Spicamycin Analogue KRN5500 and Chemotherapeutic Agents Synergistically Enhances Their Cytotoxicity in Human Myeloma Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4783-4783
Author(s):  
Hirokazu Miki ◽  
Shuji Ozaki ◽  
Osamu Tanaka ◽  
Shiro Fujii ◽  
Shingen Nakamura ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Cell Growth ◽  
Cell Lines ◽  
Therapeutic Potential ◽  
Flow Cytometric Analysis ◽  
Human Tumor ◽  
Chemotherapeutic Agents ◽  
Dependent Manner ◽  
Induced Apoptosis ◽  
Rpmi 8226

Abstract Multiple myeloma (MM) is a plasma cell malignancy characterized by the accumulation of neoplastic plasma cells in the bone marrow. Although new classes of agents such as thalidomide, lenalidomide, and bortezomib have shown marked anti-MM activity in clinical settings, MM remains an incurable disease due to increased resistance to these agents. Therefore, alternative approaches are necessary to overcome drug resistance in MM. KRN5500 is a new derivative of spicamycin produced by Streptomyces alanosinicus (Kirin Pharma, Tokyo, Japan). This drug potently decreases protein synthesis and inhibits cell growth in human tumor cell lines both in vitro and in vivo. Several phase I studies of KRN5500 were conducted in patients with solid tumors, which showed Cmax values of 1000–3000 nM at the maximum tolerated doses. However, no objective anti-tumor response to KRN5500 alone was observed in these patients. In this study, we examined the anti-tumor activity of KRN5500 against MM cells and evaluated its therapeutic potential in combination with other anti-MM agents. MM cell lines and freshly-isolated MM cells were incubated with various concentrations of KRN5500 for 24 hours. Cell proliferation assay showed marked inhibition of cell growth in MM cells such as RPMI 8226, KMS12-BM, and UTMC-2 (IC50 = 10–40 nM), and U266, MM.1S, and primary MM cells (IC50 = 500–1000 nM). Importantly, a chemotherapy-resistant subclone of RPMI 8226 had a similar sensitivity to KRN5500. Annexin V/propidium iodide staining confirmed that KRN5500 induced apoptosis of MM cells in a dose- and time-dependent manner. Moreover, cleavage of poly (ADP-ribose) polymerase (PARP) was detected after 24 hours with only modest activation of caspase-8, -9, and -3 by immunoblotting. Flow cytometric analysis of anti-apoptotic proteins revealed that apoptosis induced by KRN5500 was associated with down-regulation of Mcl-1 and Bcl-2 expression. To determine the effect of KRN5500 on the unfolded protein response (UPR), splicing of XBP-1 mRNA was analyzed by reverse transcription-polymerase chain reaction. In response to stimulation with KRN5500, splicing of XBP-1 mRNA occurred after 24 hours in RPMI 8226 cells, suggesting that KRN5500-induced apoptosis is mediated in part by the inhibition of UPR. Furthermore, synergistic effects on MM cells were observed when KRN5500 was combined with anti-MM agents including melphalan, dexamethasone, and bortezomib. These results suggest that KRN5500 induces apoptosis in MM cells mainly by the caspase-independent pathway and that its unique mechanism of action provides a valuable therapeutic option to overcome drug resistance in patients with MM.

CKS1B Mediates SKP2/p27Kip1-Independent Myeloma Cell Survival and Disease Progression through Activation of MEK/ERK and JAK/STAT3 Signaling Pathways.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 126-126 ◽  
Author(s):  
Fenghuang Zhan ◽  
Lei Shi ◽  
Siqing Wang ◽  
Hongwei Xu ◽  
Thai M. Cao ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Death ◽  
Cell Growth ◽  
Growth Inhibition ◽  
Signaling Pathways ◽  
Disease Progression ◽  
Growth And Survival ◽  
Transfected Cells ◽  
Over Expression ◽  
Empty Vector

Abstract Abstract 126 We previously reported that CKS1B may influence myeloma (MM) cell growth and survival through SKP2/p27Kip1-dependent and -independent mechanisms. However, there is still no direct evidence to prove that CKS1B has a role in MM cell proliferation and disease progression. The present study was performed to establish its functional role and define CKS1B-mediated SKP2/p27Kip1-independent down-stream signaling pathways. CKS1B was over-expressed in OCI-MY5 and XG1 MM cell lines by lentivirus. Western blots confirmed CKS1B over-expression. Cells were cultured in medium containing 1% fetal bovine serum for 7 days. CKS1B-transfection resulted in increased cell proliferation compared to empty-vector (EV)-transfected controls. We also examined the role of CKS1B in myeloma resistance to the general used chemotherapeutic drugs, such as bortezomib (5nM), doxorubicin (100nM) and etoposide (100nM). Untreated cells and empty-vector (EV)-transfected cells with or without drug treatments served as controls. Significant less inhibition of cell growth and cell death was observed after drug treatment in CKS1B-transfected cells compared with controls (P < .05). To screen down-stream signaling pathways associated with cell growth and survival in OCI-MY5, MS28PE and XG-1 cells were transfected with specific CKS1B-shRNA, which resulted in decreased phosphorylation of MEK1/2, ERK1/2, STAT3, MCL1 and BCL2 compared to wild-type and control cells, transfected with scrambled CKS1B-shRNA. To confirm these results, we examined the alteration of STAT3, MEK/ERK and BCL2 signaling pathways in OCI-MY5 and XG1 cells after forced over-expression of CKS1B. Increased levels of p-MEK1/2, p-ERK1/2, p-STAT3, MCL1 and p-BCL2 were observed compared to the EV-transfected controls, confirming that CKS1B activates STAT3, MEK/ERK and BCL2 signaling pathways. In Contrast, SKP2 over-expression or p27Kip1 inhibition resulted in inhibition of STAT3 and MEK/ERK pathways with no remarkable changes inBCL2. Further investigation showed that BCL2 is a downstream target of MEK/ERK signaling. Stimulation of STAT3, MEK/ERK and BCL2 signaling pathways only partially abrogated MM cell death and growth inhibition induced by CKS1B knockdown. Targeting either the STAT3, MEK/ERK or BCL2 signaling pathway with specific inhibitors induced significant MM cell death and growth inhibition in CKS1B-over-expressing MM cells; their combination had a synergistic effect on cell death and growth inhibition. Our findings provide a rationale for targeting STAT3 and MEK/ERK/BCL2 signaling in the therapy of aggressive CKS1B-overexpressing MM, which shows increased proliferation and drug-resistance Disclosures: No relevant conflicts of interest to declare.

The underlying mechanism contributing to P-gp over-expression and drug resistance in the MCF-7 breast cancer cells induced by adriamycin.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e12028-e12028
Author(s):  
Guangji Wang ◽  
Jiye Aa ◽  
Chun Ge
Keyword(s):  
Breast Cancer ◽  
Drug Resistance ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Underlying Mechanism ◽  
Ros Generation ◽  
Down Regulation ◽  
Over Expression ◽  
And Function ◽  
Mcf 7

e12028 Background: Continuous exposure of breast cancer cells to adriamycin (ADR) induces the over-expression of P-glycoprotein (P-gp) and multiple drug resistance. However, the biochemical process and underlying mechanisms are not clear. Our previous study revealed that ADR increased reactive oxygen species (ROS) generation and reduced glutathione (GSH) biosynthesis, while N-acetylcysteine, the ROS scavenger, reversed the over-expressed P-gp induced by ADR. Methods: Based on MCF-7 breast cancer cells and the adriamycin-resistant MCF-7 subline (MCF-7R), we investigated the P-gp expression on mRNA, protein and function level by qPCR, western blotting, flow cytometry and laser scanning confocal and so on, under SLC7A11 down-regulation/over-expression, cystine depletion/supplement, increased ROS generation and combined factors. Results: The present study showed that ADR inhibited cystine influx (source material of GSH) and SLC7A11 transporter (in charge of cystine uptake) in MCF-7 cells. For the first time, we showed that a down-regulation/silence of SLC7A11, or cystine deprivation, or an enhanced exposure of ROS agents directly and significantly increased P-gp expression; yet, a combination of either an inhibited/silenced SLC7A11 or cystine deprivation and an increased ROS dramatically promoted the P-gp expression in MCF-7 cells. On the contrary, an over-expression of SLC7A11, or sufficiently supplementary cystine, or scavenger of ROS significantly depressed P-gp expression and activity. Moreover, the down-regulation of SLC7A11 and cystine deprivation induced an elevation of ROS and P-gp that could be reversed by N-acetylcysteine. It was suggested that ROS and SLC7A11/cystine were the two relevant factors responsible for the upregulated expression and function of P-gp. Conclusions: This study provided the direct evidences suggesting that ROS triggered over-expression of P-gp and demonstrated that the combination of either an inhibition of SLC7A11 or cystine influx and elevated ROS was the underlying mechanism contributing to P-gp over-expression induced by ADR. It was indicated that the SLC7A11 might be a potential target modulating ADR resistance.

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