Cisplatin-induced downregulation of SOX1 increases drug resistance by activating autophagy in non-small cell lung cancer cell. Biochem Biophys Res Commun. 2013;439:187-190. [PMID: 23994634 DOI: 10.1016/j.bbrc.2013.08.065]

Regulation of autophagy gene expression and its implications in cancer

Autophagy is a catabolic cellular process that targets and eliminates superfluous cytoplasmic components via lysosomal degradation. This evolutionarily conserved process is tightly regulated at multiple levels as it is critical for the maintenance of homeostasis. Research in the past decade has established that dysregulation of autophagy plays a major role in various diseases, such as cancer and neurodegeneration. However, modulation of autophagy as a therapeutic strategy requires identification of key players that can fine tune the induction of autophagy without complete abrogation. In this Review, we summarize the recent discoveries on the mechanism of regulation of ATG (autophagy related) gene expression at the level of transcription, post transcription and translation. Furthermore, we briefly discuss the role of aberrant expression of ATG genes in the context of cancer.

Crosstalk between Ca2+ Signaling and Cancer Stemness: The Link to Cisplatin Resistance

In the fight against cancer, therapeutic strategies using cisplatin are severely limited by the appearance of a resistant phenotype. While cisplatin is usually efficient at the beginning of the treatment, several patients endure resistance to this agent and face relapse. One of the reasons for this resistant phenotype is the emergence of a cell subpopulation known as cancer stem cells (CSCs). Due to their quiescent phenotype and self-renewal abilities, these cells have recently been recognized as a crucial field of investigation in cancer and treatment resistance. Changes in intracellular calcium (Ca²⁺) through Ca²⁺ channel activity are essential for many cellular processes such as proliferation, migration, differentiation, and survival in various cell types. It is now proved that altered Ca²⁺ signaling is a hallmark of cancer, and several Ca²⁺ channels have been linked to CSC functions and therapy resistance. Moreover, cisplatin was shown to interfere with Ca²⁺ homeostasis; thus, it is considered likely that cisplatin-induced aberrant Ca²⁺ signaling is linked to CSCs biology and, therefore, therapy failure. The molecular signature defining the resistant phenotype varies between tumors, and the number of resistance mechanisms activated in response to a range of pressures dictates the global degree of cisplatin resistance. However, if we can understand the molecular mechanisms linking Ca²⁺ to cisplatin-induced resistance and CSC behaviors, alternative and novel therapeutic strategies could be considered. In this review, we examine how cisplatin interferes with Ca²⁺ homeostasis in tumor cells. We also summarize how cisplatin induces CSC markers in cancer. Finally, we highlight the role of Ca²⁺ in cancer stemness and focus on how they are involved in cisplatin-induced resistance through the increase of cancer stem cell populations and via specific pathways.

DNA Methylation Biomarkers for Prediction of Response to Platinum-Based Chemotherapy: Where Do We Stand?

Simple Summary

Platinum-based agents are one of the most widely used chemotherapy drugs for various types of cancer. However, one of the main challenges in the application of platinum drugs is resistance, which is currently being widely investigated. Epigenetic DNA methylation-based biomarkers are promising to aid in the selection of patients, helping to foresee their platinum therapy response in advance. These biomarkers enable minimally invasive patient sample collection, short analysis, and good sensitivity. Hence, improved methodologies for the detection and quantification of DNA methylation biomarkers will facilitate their use in the choice of an optimal treatment strategy.

Abstract

Platinum-based chemotherapy is routinely used for the treatment of several cancers. Despite all the advances made in cancer research regarding this therapy and its mechanisms of action, tumor resistance remains a major concern, limiting its effectiveness. DNA methylation-based biomarkers may assist in the selection of patients that may benefit (or not) from this type of treatment and provide new targets to circumvent platinum chemoresistance, namely, through demethylating agents. We performed a systematic search of studies on biomarkers that might be predictive of platinum-based chemotherapy resistance, including in vitro and in vivo pre-clinical models and clinical studies using patient samples. DNA methylation biomarkers predictive of response to platinum remain mostly unexplored but seem promising in assisting clinicians in the generation of more personalized follow-up and treatment strategies. Improved methodologies for their detection and quantification, including non-invasively in liquid biopsies, are additional attractive features that can bring these biomarkers into clinical practice, fostering precision medicine.

Interferon regulatory factor-1 regulates cisplatin-induced apoptosis and autophagy in A549 lung cancer cells

This study aimed to investigate the expression and function of interferon regulatory factor-1 (IRF-1) in non-small cell lung cancer (NSCLC). IRF-1 expression and its prognostic value were investigated through bioinformatic analysis. The protein expression levels of IRF-1, cleaved caspase 3, and LC3-I/II were analyzed by western blotting. A lentiviral vector was used to overexpress or knockdown IRF-1 in vitro. Mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were analyzed by JC-1 and DCFH-DA staining, respectively. ATP, SOD, MDA, cell viability, LDH release, and caspase 3 activity were evaluated using commercial kits. Compared to the levels in normal tissues, IRF-1 expression was significantly lower in lung cancer tissues and was a prognostic factor for NSCLC. Cisplatin treatment-induced IRF-1 activation, ROS production, ATP depletion, SOD consumption, and MDA accumulation in A549 lung cancer cells. IRF-1 overexpression promoted mitochondrial depolarization, oxidative stress, and apoptotic cell death and inhibited autophagy in A549 cells, and these effects could be reversed by IRF-1 knockdown. These data suggest that IRF-1 regulates apoptosis, autophagy and oxidative stress, which might be served as a potential target for increasing chemotherapy sensitivity of lung cancer.

The role of SOX family transcription factors in gastric cancer

Gastric cancer (GC) is a leading cause of death worldwide. GC is the third-most common cause of cancer-related death after lung and colorectal cancer. It is also the fifth-most commonly diagnosed cancer. Accumulating evidence has revealed the role of signaling networks in GC progression. Identification of these molecular pathways can provide new insight into therapeutic approaches for GC. Several molecular factors involved in GC can play both onco-suppressor and oncogene roles. Sex-determining region Y (Sry)-box-containing (SOX) family members are transcription factors with a well-known role in cancer. SOX proteins can bind to DNA to regulate cellular pathways via a highly conserved domain known as high mobility group (HMG). In the present review, the roles of SOX proteins in the progression and/or inhibition of GC are discussed. The dual role of SOX proteins as tumor-promoting and tumor-suppressing factors is highlighted. SOX members can affect upstream mediators (microRNAs, long non-coding RNAs and NF-κB) and down-stream mediators (FAK, HIF-1α, CDX2 and PTEN) in GC. The possible role of anti-tumor compounds to target SOX pathway members in GC therapy is described. Moreover, SOX proteins may be used as diagnostic or prognostic biomarkers in GC.

Negative Regulation of ULK1 by microRNA-106a in Autophagy Induced by a Triple Drug Combination in Colorectal Cancer Cells In Vitro

Colorectal cancer (CRC) is among the top three most deadly cancers worldwide. The survival rate for this disease has not been reduced despite the treatments, the reason why the search for therapeutic alternatives continues to be a priority issue in oncology. In this research work, we tested our successful pharmacological combination of three drugs, metformin, doxorubicin, and sodium oxamate (triple therapy, or TT), as an autophagy inducer. Firstly, we employed western blot (WB) assays, where we observed that after 8 h of stimulation with TT, the proteins Unc-51 like autophagy activating kinase 1(ULK1), becline-1, autophagy related 1 protein (Atg4), and LC3 increased in the CRC cell lines HCT116 and SW480 in contrast to monotherapy with doxorubicin. The overexpression of these proteins indicated the beginning of autophagy flow through the activation of ULK1 and the hyperlipidation of LC3 at the beginning of this process. Moreover, we confirm that ULK1 is a bona fide target of hsa-miR-106a-5p (referred to from here on as miR-106a) in HCT116. We also observed through the GFP-LC3 fusion protein that in the presence of miR-106a, the accumulation of autophagy vesicles in cells stimulated with TT is inhibited. These results show that the TT triggered autophagy to modulate miR-106a/ULK1 expression, probably affecting different cellular pathways involved in cellular proliferation, survivance, metabolic maintenance, and cell death. Therefore, considering the importance of autophagy in cancer biology, the study of miRNAs that regulate autophagy in cancer will allow a better understanding of malignant tumors and lead to the development of new disease markers and therapeutic strategies.

SOX1 and PAX1 Are Hypermethylated in Cervical Adenocarcinoma and Associated with Better Prognosis

Background

The increased risk and poor survival outcome of cervical adenocarcinoma (CAC) demand for effective early diagnostic biomarkers that can predict the disease progression and outcome. The purpose of this study was to investigate the value of methylation status of SOX1 and PAX1 in the detection and prognosis of CAC.

Methods

We performed a quantitative methylation-specific polymerase chain reaction in 205 cervical paraffin-embedded specimens (175 CACs, 30 noncancer cervical tissues). Overall and progression-free survival (OS and PFS, respectively) rates were calculated and compared using the Kaplan-Meier method. The prognostic value of SOX1^m and PAX1^m on CAC patients was assessed by the Cox regression model. A mathematical formula combining SOX1^m, PAX1^m, and age was constructed for survival prediction.

Results

The methylation status of SOX1 and PAX1 was higher in CAC tissues than in noncancer cervical tissues. In addition, SOX1^m-positive CAC patients showed a higher 5-year OS rate than SOX1^m-negative patients. In CAC patients with smaller tumor size (<4 cm), the PAX1^m-positive group showed a higher 5-year PFS rate than the PAX1^m-negative group. In the algorithm combining SOX1^m, PAX1^m, and age, the low-risk group showed a better 5-year OS and PFS rate than the high-risk group.

Conclusion

SOX1 and PAX1 methylation levels are higher in CAC than in normal cervical tissues and are potential biomarkers for monitoring CAC prognosis.

Cancer and SOX proteins: New insight into their role in ovarian cancer progression/inhibition

Transcription factors are potential targets in disease therapy, particularly in cancer. This is due to the fact that transcription factors regulate a variety of cellular events, and their modulation has opened a new window in cancer therapy. Sex-determining region Y (SRY)-related high-mobility group (HMG) box (SOX) proteins are potential transcription factors that are involved in developmental processes such as embryogenesis. It has been reported that abnormal expression of SOX proteins is associated with development of different cancers, particularly ovarian cancer (OC). In the present review, our aim is to provide a mechanistic review of involvement of SOX members in OC. SOX members may suppress and/or promote aggressiveness and proliferation of OC cells. Clinical studies have also confirmed the potential of transcription factors as diagnostic and prognostic factors in OC. Notably, studies have demonstrated the relationship between SOX members and other molecular pathways such as ST6Ga1-I, PI3K, ERK and so on, leading to more complexity. Furthermore, SOX members can be affected by upstream mediators such as microRNAs, long non-coding RNAs, and so on. It is worth mentioning that the expression of each member of SOX proteins is corelated with different stages of OC. Furthermore, their expression determines the response of OC cells to chemotherapy. These topics are discussed in this review to shed some light on role of SOX transcription factors in OC.

Inhibition of p90 ribosomal S6 kinase potentiates cisplatin activity in A549 human lung adenocarcinoma cells

OBJECTIVE

Cisplatin is a standard treatment approach against lung adenocarcinoma. Resistance to cisplatin and the toxic side effects of cisplatin continue to remain a challenge. Combining drugs with different mechanisms is being investigated as a means to overcome these challenges. In ovarian cancer cells, the knockdown of RSK2 increased the sensitivity of cisplatin. RSK is a downstream mediator of the MAPK pathway that is responsible for cell survival, proliferation and migration.

METHODS

Our study examined the effect of cisplatin, BI-D1870 (RSK inhibitor) or their combination on cell migration, apoptosis, autophagy and cell cycle in A549 human lung adenocarcinoma cells.

KEY FINDINGS

The combination of cisplatin and BI-D1870 potentiated the antimigration rate, the activation of caspases-3 and was associated with a significant decrease in RSK1 and ERK expression when compared to cisplatin alone. The combination of cisplatin and BI-D1870 also resulted in the inhibition of LC3 II to LC3 I expression when compared to BI-D1870. The combination of cisplatin and BI-D1870 increased the number of cells in the G2/M-phase when compared to cisplatin alone.

CONCLUSIONS

These findings suggest that combining cisplatin with agents that target the RSK mediated cell survival pathway, may potentiate the cisplatin effect in lung adenocarcinoma.

Transcriptional regulation of autophagy-lysosomal pathway in cancer

The transcriptional regulation of autophagy‐lysosomal pathway adapts to cellular stress and enables advanced cancer cells survive. This pathway plays an oncopromoting or oncosuppressing role, depending on context‐dependent stresses and treatment resistance. It remains controversial whether this pathway represents a target for drugs, although autophagy‐lysosomal inducers and inhibitors have been tested in clinical trials for cancer treatment. Therefore, identifying the transcriptional regulators of autophagy‐lysosomal pathway may lead to the development of effective cancer treatment and the improvement of the existing targeted cancer therapies. In this review, we summarize findings from several published studies on transcriptional regulation of autophagy‐lysosomal pathway in cancer biology, and evaluate its functional role as a therapeutic target.

Predictive and prognostic implications of 4E-BP1, Beclin-1, and LC3 for cetuximab treatment combined with chemotherapy in advanced colorectal cancer with wild-type KRAS: Analysis from real-world data

BACKGROUND

Colorectal cancer (CRC) is one of the main causes of cancer-related deaths in China and around the world. Advanced CRC (ACRC) patients suffer from a low cure rate though treated with targeted therapies. The response rate is about 50% to chemotherapy and cetuximab, a monoclonal antibody targeting epidermal growth factor receptor (EGFR) and used for ACRC with wild-type KRAS. It is important to identify more predictors of cetuximab efficacy to further improve precise treatment. Autophagy, showing a key role in the cancer progression, is influenced by the EGFR pathway. Whether autophagy can predict cetuximab efficacy in ACRC is an interesting topic.

AIM

To investigate the effect of autophagy on the efficacy of cetuximab in colon cancer cells and ACRC patients with wild-type KRAS.

METHODS

ACRC patients treated with cetuximab plus chemotherapy, with detailed data and tumor tissue, at Sun Yat-sen University Cancer Center from January 1, 2005, to October 1, 2015, were studied. Expression of autophagy-related proteins [Beclin1, microtubule-associated protein 1A/B-light chain 3 (LC3), and 4E-binding protein 1 (4E-BP1)] was examined by Western blot in CRC cells and by immunohistochemistry in cancerous and normal tissues. The effect of autophagy on cetuximab-treated cancer cells was confirmed by MTT assay. The associations between Beclin1, LC3, and 4E-BP1 expression in tumor tissue and the efficacy of cetuximab-based therapy were analyzed.

RESULTS

In CACO-2 cells exposed to cetuximab, LC3 and 4E-BP1 were upregulated, and P62 was downregulated. Autophagosome formation was observed, and autophagy increased the efficacy of cetuximab. In 68 ACRC patients, immunohistochemistry showed that Beclin1 levels were significantly correlated with those of LC3 (0.657, P < 0.001) and 4E-BP1 (0.211, P = 0.042) in ACRC tissues. LC3 was significantly overexpressed in tumor tissues compared to normal tissues (P < 0.001). In 45 patients with wild-type KRAS, the expression levels of these three proteins were not related to progression-free survival; however, the expression levels of Beclin1 (P = 0.010) and 4E-BP1 (P = 0.005), pathological grade (P = 0.002), and T stage (P = 0.004) were independent prognostic factors for overall survival (OS).

CONCLUSION

The effect of cetuximab on colon cancer cells might be improved by autophagy. LC3 is overexpressed in tumor tissues, and Beclin1 and 4E-BP1 could be significant predictors of OS in ACRC patients treated with cetuximab.

Genome-wide methylome analysis using MethylCap-seq uncovers 4 hypermethylated markers with high sensitivity for both adeno- and squamous-cell cervical carcinoma

Background

Cytology-based screening methods for cervical adenocarcinoma (ADC) and to a lesser extent squamous-cell carcinoma (SCC) suffer from low sensitivity. DNA hypermethylation analysis in cervical scrapings may improve detection of SCC, but few methylation markers have been described for ADC. We aimed to identify novel methylation markers for the early detection of both ADC and SCC.

Results

Genome-wide methylation profiling for 20 normal cervices, 6 ADC and 6 SCC using MethylCap-seq yielded 53 candidate regions hypermethylated in both ADC and SCC. Verification and independent validation of the 15 most significant regions revealed 5 markers with differential methylation between 17 normals and 13 cancers. Quantitative methylation-specific PCR on cervical cancer scrapings resulted in detection rates ranging between 80% and 92% while between 94% and 99% of control scrapings tested negative. Four markers (SLC6A5, SOX1, SOX14 and TBX20) detected ADC and SCC with similar sensitivity. In scrapings from women referred with an abnormal smear (n=229), CIN3+ sensitivity was between 36% and 71%, while between 71% and 93% of adenocarcinoma in situ (AdCIS) were detected; and CIN0/1 specificity was between 88% and 98%. Compared to hrHPV, the combination SOX1/SOX14 showed a similar CIN3+ sensitivity (80% vs. 75%, respectively, P>0.2), while specificity improved (42% vs. 84%, respectively, P < 10^-5).

Conclusion

SOX1 and SOX14 are methylation biomarkers applicable for screening of all cervical cancer types.

[Advances in the Research of the Regulation of Chinese Traditional Medicine Monomer and Its Derivatives on Autophagy in Non-small Cell Lung Cancer]

The high morbidity and mortality of non-small cell lung cancer (NSCLC) did influence the quality of life of tumor patients world-wide. There is an urgent need to develop new therapies that have high anti-tumor activity and low toxicity side effects. It is widely accepted that autophagy can play diverse roles in carcinogenesis, such as induces pro-death of lung cancer cells or helps the escape from cell death, making it become a proper anticancer target. It's believed that various monomers of Chinese traditional medicine closely correlates to anti-NSCLC activities, and that even could affect the acquired multiple drug resistance (MDR). Furthermore, autophagy might be the underling mechanisms which could play a role as the candidate targets of natural active compounds. Recent studies of terpenoids, alkaloid, dietary polyphenols, saponins and other active ingredients that extracted from a large variety of herbs suggest that different monomer compounds could either regulate the activity of pro-death autophagy or influence the level of protective autophagy of NSCLC cells, thus changing their drug sensitivity and cell viability. This paper aims to give a systemic description of the latest advances about natural compounds and their derivatives that involved in tumorigenesis of NSCLC via inducing the autophagy.

Sensitization of multidrug-resistant malignant cells by liposomes co-encapsulating doxorubicin and chloroquine through autophagic inhibition

Adenosine triphosphate (ATP)-binding cassette (ABC) transporters play a key role in the development of multidrug resistance (MDR) in cancer cells. P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1) are important proteins in this superfamily which are widely expressed on the membranes of multidrug resistance (MDR) cancer cells. Besides, upregulation of cellular autophagic responses is considered a contributing factor for MDR in cancer cells. We designed a liposome system co-encapsulating a chemotherapeutic drug (doxorubicin hydrochloride, DOX) and a typical autophagy inhibitior (chloroquine phosphate, CQ) at a weight ratio of 1:2 and investigated its drug resistance reversal mechanism. MTT assay showed that the IC₅₀ of DOX/CQ co-encapsulated liposome in DOX-resistant human breast cancer cells (MCF7/ADR) was 4.7 ± 0.2 μM, 5.7-fold less than that of free DOX (26.9 ± 1.9  μM), whereas it was 19.5-fold in doxorubicin-resistant human acute myelocytic leukemia cancer cells (HL60/ADR) (DOX/CQ co-encapsulated liposome 1.2 ± 0.1 μM, free DOX 23.4 ± 2.8 μM). The cellular uptake of DOX increased upon addition of free CQ, indicating that CQ may interact with P-gp and MRP1; however, the expressions of P-gp and MRP1 remained unchanged. In contrast, the expression of the autophagy-related protein LC3-II increased remarkably. Therefore, the mechanism of MDR reversal may be closely related to autophagic inhibition. Evaluation of anti-tumor activity was achieved in an MCF-7/ADR multicellular tumor spheroid model and transgenic zebrafish model. DOX/CQ co-encapsulated liposome exerted a better anti-tumor effect in both models than that of liposomal DOX or DOX alone. These findings suggest that encapsulating CQ with DOX in liposomes significantly improves the sensitivity of DOX in DOX-resistant cancer cells.

Exploiting the potential of autophagy in cisplatin therapy: A new strategy to overcome resistance

Resistance to cisplatin is a major challenge in the current cancer therapy. In order to explore new therapeutic strategies to cisplatin resistance, we evaluated, in a model of lung cancer (H1299 and H460 cell lines), the nature of the pathways leading to cell death. We observed that H1299 displayed a natural resistance to cisplatin due to an inability to trigger an apoptotic response that correlates with the induction of autophagy. However, pharmacological and genetic approaches showed how autophagy was a mechanism associated to cell death rather than to resistance. Indeed, pro-autophagic stimuli such as mTOR or Akt inhibition mediate cell death in both cell lines to a similar extent. We next evaluated the response to a novel platinum compound, monoplatin, able to promote cell death in an exclusive autophagy-dependent manner. In this case, no differences were observed between both cell lines. Furthermore, in response to monoplatin, two molecular hallmarks of cisplatin response (p53 and MAPKs) were not implicated, indicating the ability of this pro-autophagic compound to overcome cisplatin resistance. In summary, our data highlight how induction of autophagy could be used in cisplatin resistant tumours and an alternative treatment for p53 mutated patient in a synthetic lethally approach.

Autophagy-related genes Raptor, Rictor, and Beclin1 expression and relationship with multidrug resistance in colorectal carcinoma

This study aims to evaluate the relationship between the expressions of autophagy-related genes Raptor, Rictor, and Beclin1 and the expression of multidrug resistance (MDR) gene in colorectal cancer (CRC) patients. Immunohistochemistry and real-time polymerase chain reaction were used to detect the protein and messenger RNA expressions of mammalian target of rapamycin (mTOR), Raptor, Rictor, Beclin1, light chain 3 (LC3), and MDR-1 in 279 CRC specimens. Patients were followed up annually by telephone or at an outpatient clinic. Results revealed that the protein and messenger RNA expressions of Beclin1, LC3, mTOR, Raptor, Rictor, and MDR-1 in CRC are significantly higher than in adjacent tissues. LC3 expression in poorly differentiated CRC is higher than that in well-differentiated CRC, and the expression of mTOR, Raptor, Rictor, and LC3 in lymph node metastasis is higher than that obtained in the absence of lymph node metastasis. The expression of LC3 is positively correlated with those of Beclin1 and Rictor and negatively correlated with Raptor and mTOR in CRC. The expression of Raptor is negatively correlated with Rictor. The expression of MDR-1 is positively correlated with those of Beclin1, LC3, and Rictor and negatively correlated with Raptor and mTOR. Kaplan-Meier analysis revealed that the 5-year survival rate of patients without lymph node metastasis; positive expression of Rictor, Beclin1, and LC3; and negative expression of Raptor and mTOR were higher than those with these characteristics. To conclude, the expressions of Beclin1, Raptor, and Rictor are related to the development and progression of colorectal carcinoma and MDR. (

CLINICAL TRIAL REGISTRATION NUMBER

2014-009-01.).

RASAL2 promotes lung cancer metastasis through epithelial-mesenchymal transition

It was reported that genetically-engineered RASAL2 knockout mice are prone to development of several sporadic tumor, including lung adenocarcinoma. However, a causative relationship between RASAL2 deficiency and lung adenocarcinoma development still remains unknown. In the present study, RASAL2 level was determined in patients with lung adenocarcinoma and control subjects in an attempt to explore its potential clinical diagnostic and prognostic value. Low RASAL2 expression levels were found in 71% (37 of 52) of lung adenocarcinoma, which were correlated with lymph node metastasis in lung adenocarcinoma. Moreover, Low RASAL2 expression levels were correlated with reduced overall survival (OS) in lung adenocarcinoma. We find that inactivation of RASAL2 promotes lung cancer cell migration through the induction of epithelial mesenchymal transition (EMT) and promoted lung metastasis in nude mice. Our results suggest that the down-regulation of RASAL2 promotes metastatic progression of lung adenocarcinoma, hence it could serve as a potential target for the development of lung cancer therapies.

Epigenetic silencing of MicroRNA-503 regulates FANCA expression in non-small cell lung cancer cell

It is reported that MicroRNA-503 (miR-503) regulates cell apoptosis, and thus modulates the resistance of non-small cell lung cancer cells (NSCLC) to cisplatin. However, the exact role of miR-503 in NSCLC remains unknown. In the present study, the level of miR-503 expression in NSCLC was evaluated using realtime PCR, and the DNA methylation status within miR-503 promoter was analyzed by Combined Bisulfite Restriction Analysis (COBRA) or bisulfite-treated DNA sequencing assays (BSP). We found that the expression of miR-503 was significantly decreased in NSCLC tissues compared to normal tissues. A statistically significant inverse association was found between miR-503 methylation status and expression of the miR-503 in tumor tissues (P<0.001), and expression of miR-503 was restored by the demethylating agent 5-aza-2'-deoxycytidine, suggesting that methylation was associated with the transcriptional silencing. Then, we show that miR-503 targets a homologous DNA region in the 3'-UTR region of the Fanconi anemia complementation group A protein (FANCA) gene and represses its expression at the transcriptional level. Taken together, our results suggest that miR-503 regulates the resistance of non-small cell lung cancer cells to cisplatin at least in part by targeting FANCA.