Field-effect transistor bioassay for ultrasensitive detection of folate receptor 1 by ligand-protein interaction.

A miniaturized and integrated bioassay was developed based on molybdenum disulfide (MoS2) field-effect transistor (FET) functionalized with bovine serum albumin-folic acid (BSA-FA) for monitoring FOLR1. We performed the electrical test of FOLR1 within the range 100 fg/mL to 10 ng/mL, and the limit of detection was 0.057 pg/mL. The ultrahigh sensitivity of the bioassay was realized by ligand-protein interaction between FA and FOLR1, with a ligand-protein binding ratio of 3:1. The formation of FA-FOLR1 was confirmed with ELISA. The binding affinity dissociation constant KD was 12 ± 6 pg/mL. This device can work well for FOLR1 detection in human serum, which presents its promising application in point-of-care diagnosis. This study supports the future applications of such ligand-protein-based bioassays in the clinical practices. Graphical abstract MoS2-based FET device for detecting folate receptor 1 (FOLR1) was fabricated. The molecular folic acid as a probe can specifically bound to FOLR1 with a high affinity.

Folate-receptor 1 level in periodontal disease: a pilot study.

BACKGROUND: The purpose of this study was to investigate gingival crevicular fluid (GCF) and serum folate-receptor 1 (FOLR1) levels in subjects with different periodontal status. METHODS: The study consists of three groups: Healthy group (n = 15), gingivitis group (n = 15) and chronic periodontitis group (n = 15). Clinical periodontal parameters including probing pocket depth (PPD), clinical attachment level (CAL), gingival index (GI) and bleeding on probing (BOP) were assessed. GCF and serum samples were collected from each patient and were analyzed FOLR1 levels by enzyme-linked immunosorbent assay. RESULTS: The values of FOLR1 in GCF were higher in gingivitis and periodontitis groups than among patient in control group (p < 0.016). Serum FOLR1 levels showed no significant difference between the groups. A significant correlation was observed between FOLR1 levels of GCF and BOP (p < 0.05). CONCLUSIONS: Our preliminary data suggest that FOLR1 is not useful in monitoring the periodontal disease. Further studies are necessary to clarify the role, regulation and function of folate and it's receptors in the pathogenesis of periodontal disease.

Evaluation of folate receptor 1 (FOLR1) mRNA expression, its specific promoter methylation and global DNA hypomethylation in type I and type II ovarian cancers.

BACKGROUND: In this retrospective study we evaluated the respective correlations and clinical relevance of FOLR1 mRNA expression, FOLR1 promoter specific methylation and global DNA hypomethylation in type I and type II ovarian cancer. METHODS: Two hundred fifty four ovarian cancers, 13 borderline tumours and 60 samples of healthy fallopian epithelium and normal ovarian epithelium were retrospectively analysed for FOLR1 expression with RT-PCR. FOLR1 DNA promoter methylation and global DNA hypomethylation (measured by means of LINE1 DNA hypomethylation) were evaluated with MethyLight technique. RESULTS: No correlation between FOLR1 mRNA expression and its specific promoter DNA methylation was found neither in type I nor in type II cancers, however, high FOLR1 mRNA expression was found to be correlated with global DNA hypomethylation in type II cancers (p = 0.033). Strong FOLR1 mRNA expression was revealed for Grades 2-3, FIGO stages III-IV, residual disease > 0, and serous histotype. High FOLR1 expression was found to predict increased platinum sensitivity in type I cancers (odds ratio = 3.288; 1.256-10.75; p = 0.020). One-year survival analysis showed in type I cancers an independent better outcome for strong expression of FOLR1 in FIGO stage III and IV. For the entire follow up period no significant independent outcome for FOLR1 expression was revealed. In type I cancers LINE 1 DNA hypomethylation was found to exhibit a worse PFS and OS which were confirmed to be independent in multivariate COX regression model for both PFS (p = 0.026) and OS (p = 0.012). CONCLUSION: No correlations were found between FOLR1 expression and its specific promoter methylation, however, high FOLR1 mRNA expression was associated with DNA hypomethylation in type II cancers. FOLR1 mRNA expression did not prove to predict clinical outcome in type II cancers, although strong FOLR1 expression generally denotes ovarian cancers with highly aggressive phenotype. In type I cancers, however, strong FOLR1 expression has been found to be a reliable indicator of improved platinum responsiveness reflecting a transient better one-year follow up outcome in highly FOLR1 expressing type I cancers. An independent prognostic role of global DNA hypomethylation was demonstrated in type I tumours.

Folate receptor alpha autoantibodies in the serum of patients with relapsing-remitting multiple sclerosis (RRMS).

OBJECTIVE: Multiple sclerosis (MS) is a potentially progressive, autoimmune neurologic disorder of the central nervous system (CNS), resulting from an autoimmune attack on central nervous system white matter. Folate deficiencies are linked to DNA instability and breakdown of phospholipid membranes and thus might affect myelin integrity. Folic acid exerts its effects through its receptors (FRs). Folate receptor alpha autoantibodies (FRAA) can block folate transport to the brain. Due to important role of folate in the pathogenesis of MS, in this project we aimed to study FRAA serum levels in patients with relapsing remitting multiple sclerosis (RRMS). METHODS: Fifty-four patients with RRMS and 58 healthy individuals were enrolled in this study. Serum samples were collected from all participants and folate receptor alpha autoantibody (FRAA) serum concentration was measured by Enzyme-linked immunosorbent assay (ELISA). RESULTS: The results showed that FRAA serum levels in patients with RRMS is 67.20 ± 19.79 ng/ml as compared to controls which was 37.32 ± 13.26 ng/ml. Significant increase in folate receptor autoantibody serum concentration was seen in patients with RRMS when compared to control group (P = 0.007). The results showed that a high concentration of folate receptor autoantibody is associated with RRMS. We have also found that 85.18% (46/54) of patients with RRMS were positive for serum FRAA, whereas the prevalence in controls was only 46.55% (27/58). CONCLUSIONS: It is concluded that serum FRAA are more prevalent in RRMS patients than controls. The findings also suggest that FRAA might be involved in the pathophysiology of RRMS.

Surface Plasmon Resonance, a Novel Technique for Sensing Cancer Biomarker: Folate Receptor and Nanoparticles Interface.

Despite advances in healthcare technology, the early detection biomarker and treatment remain one of the biggest challenges in humanity. Thus, developing a biosensor for timely diagnosis is well-justified to improve the prospect of remission of cancer patients. Surface plasmon resonance (SPR), a biosensor, is of interest that monitors many cancer biomarkers with high sensitivity and rapidity. For various cancers, nanoparticle (NP)-based targeted drug/gene delivery has been widely employed as it directs mainly the receptors expressed specifically on the cell membrane of the cancer cell. Folate Receptor 1 (FOLR1) or FOLRα, predominantly expressed on epithelial cells, remains a principal target for drug discovery in several cancers, including prostate or ovarian. Therefore, conjugation of folic acid to the NPs precisely targeting the biomarkers on the tumor cells allows the detection and helps in the treatment of various cancers. In the present study, we discuss the folate receptor as of diagnostic interest and focus on the use of the targeted planetary ball milled nanoparticles (PBM-NPs) and its formulation, emphasizing the approach using sensor chips in the Open SPR system for cancer biomarker detection.

Folic acid inhibits 5-methyltetrahydrofolate transport across the blood-cerebrospinal fluid barrier: Clinical biochemical data from two cases.

Objective: The use of folic acid (FA) has been discouraged in cerebral folate deficiency (CFD) because, theoretically, it could inhibit the transport of 5-methyltetrahydrofolic acid (5MTHF) across the blood-cerebrospinal fluid (CSF) barrier. We present the clinical biochemical data of two cases with CFD to support this hypothesis. Methods: We measured CSF and serum 5MTHF concentrations in a patient with Kearns-Sayre syndrome (KSS) and a patient homozygous for MTHFR C677T polymorphism before and during folate supplementation therapy. To evaluate these 5MTHF concentrations, we also analyzed CSF and serum samples in pediatric patients without folate supplementation. Results: Both patients had low CSF 5MTHF before treatment and high-dose FA therapy did not normalize CSF 5MTHF. There was a dissociation between serum total folate and 5MTHF concentrations during FA therapy, which was considered to be due to the appearance of unmetabolized FA. The addition of folinic acid did not improve low CSF 5MTHF in the KSS patient and the cessation of FA resulted in the normalization of CSF 5MTHF. In the patient homozygous for MTHFR C677T, minimization of the FA dosage resulted in the normalization of CSF 5MTHF and an increased CSF-to-serum 5MTHF ratio. Conclusions: Our data suggest that excess supplementation of FA impaired 5MTHF transport across the blood-CSF barrier. In the treatment of CFD, supplementation of folinic acid or 5MTHF (in cases of impaired 5MTHF synthesis) is preferred over the use of FA. The reference values of CSF 5MTHF concentration based on 600 pediatric cases were also provided.

[Chorioretinal atrophy in pediatric cerebral folate deficiency-a preventable disease?] / Chorioretinale Atrophie bei kindlichem zerebralem Folatmangel ­ eine vermeidbare Erkrankung?

Cerebral folate deficiency (CFD) results in neurological alterations and a massive degeneration of the choroid/retina if left untreated, which limit the visual field and visual acuity. This article reports the case of a female patient with CFD, who developed autistic personal characteristics prior to reaching school age and first started to speak at the age of 3 years. At the age of 6 years she was presented because of unclear reduced visual acuity in the right eye. At that time mild bilateral peripheral chorioretinal atrophy was present, which subsequently became more pronounced. Additionally, a centrally emphasized chorioretinal atrophy further developed. Visual acuity of both eyes progressively deteriorated until stagnating at 0.1 at the age of 14 years. The causal assignment of the findings of the patient was not possible for many years. Choroideremia was excluded by molecular genetic testing (CHM gene with no mutations) and gyrate atrophy was ruled out by a normal ornithine level. The existence of a mitochondrial disease was almost completely excluded by exome sequencing. After the onset of further nonocular symptoms, e.g. neuromuscular disorders, electroencephalograph (EEG) alterations and autistic disorder, intensified laboratory diagnostics were performed in the treating pediatric hospital. Finally, an extremely low level of the folic acid metabolite 5­methyltetrahydrofolate was detected in the cerebrospinal fluid (CSF) leading to the diagnosis of CFD. High-dose substitution treatment with folic acid was subsequently initiated. After excluding the presence of a pathogenic mutation of the FOLR1 gene for the cerebral folate receptor 1, a high titer blocking autoantibody against cerebral folate receptor 1 was detected as the cause.

Genes involved with folate uptake and distribution and their association with colorectal cancer risk.

Folate status is an important predictor of colorectal cancer risk. Common genetic variants in genes involved in regulating cellular folate levels might also predict risk, but there are limited data on this issue. We conducted a family-based case-control association study of variants in four genes involved in folate uptake and distribution: FOLR1, FPGS, GGH and SLC19A1, using 1,750 population-based and 245 clinic-based cases of pathologically confirmed colorectal cancer and their unaffected relatives participating in the Colon Cancer Family Registries. Standardized questionnaires, administered to all participants, collected information on risk factors and diet. Standard molecular techniques were used to determine microsatellite instability (MSI) status on cases. tagSNPs (n = 29) were selected based on coverage as assessed by pairwise r2. We found no evidence that tagSNPs in these genes were associated with risk of colorectal cancer. For the SLC19A1-rs1051266 (G80A, Arg27His) missense polymorphism, the A/A genotype was not associated with risk of colorectal cancer using population-based (OR = 1.00; 95% CI = 0.81-1.23) or clinic-based (OR = 0.75; 95% CI = 0.44-1.29) families compared to the G/A and G/G genotypes. We found no evidence that the association between any tagSNP and CRC risk was modified by multivitamin use, folic acid use and dietary folate intake and total folate intake. The odds ratios were similar, irrespective of MSI status, tumor subsite and family history of colorectal cancer. In conclusion, we found no significant evidence that genetic variants in FOLR1, GGH, FPGS and SLC19A1 are associated with the risk of colorectal cancer.

microRNA-29b inhibits cell growth and promotes sensitivity to oxaliplatin in colon cancer by targeting FOLR1.

The present study was aimed to explore the functional role of microRNA (miR)-29b in colon cancer, as well as underlying mechanisms. Expressions of miR-29b and folate receptor 1 (FOLR1) were measured in both human colon tumor samples and cell lines. Colon cancer cell lines SW480 and SW620 were transfected with miR-29b mimic, antisense oligonucleotides (ASO)-miR-29b, small interfering (siRNA) against FOLR1 (si-FOLR1), or corresponding negative controls (NCs), and then were incubated with or without oxaliplatin (L-OHP). Thereafter, cell viability, cytotoxicity, cell apoptosis, and expression of FOLR1, ATP Binding Cassette Subfamily G Member 2 (ABCG2) and p-glycoprotein (p-gp) were analyzed. We found that miR-29b was significantly decreased, while FOLR1 was statistically elevated in colon cancer samples and cell lines compared to the nontumor samples and nontumourigenic immortalized human colon epithelial cell line FHC. Overexpression of miR-29b markedly inhibited cell viability, promoted sensitivity to L-OHP, stimulated cell apoptosis (all p < .05), and decreased the levels of ABCG2 and p-gp in cancer cells, whereas suppression of miR-29b showed contrary results. Moreover, we observed that FOLR1 was a direct target of miR-29b and was negatively regulated by miR-29b. In addition, the findings revealed that the effects of FOLR1 inhibition on cell viability, sensitivity to L-OHP, cell apoptosis, and the levels of ABCG2 and p-gp were similar to overexpression of miR-29b. Taken together, our study suggests that miR-29b inhibits cell growth and promotes sensitivity to L-OHP in colon cancer by targeting FOLR1.

Targeted Delivery of Nanoparticulate Cytochrome C into Glioma Cells Through the Proton-Coupled Folate Transporter.

In this study, we identified the proton-coupled folate transporter (PCFT) as a route for targeted delivery of drugs to some gliomas. Using the techniques of confocal imaging, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and small interfering (siRNA) knockdown against the PCFT, we demonstrated that Gl261 and A172 glioma cells, but not U87 and primary cultured astrocytes, express the PCFT, which provides selective internalization of folic acid (FA)-conjugated cytochrome c-containing nanoparticles (FA-Cyt c NPs), followed by cell death. The FA-Cyt c NPs (100 µg/mL), had no cytotoxic effects in astrocytes but caused death in glioma cells, according to their level of expression of PCFT. Whole-cell patch clamp recording revealed FA-induced membrane currents in FA-Cyt c NPs-sensitive gliomas, that were reduced by siRNA PCFT knockdown in a similar manner as by application of FA-Cyt c NPs, indicating that the PCFT is a route for internalization of FA-conjugated NPs in these glioma cells. Analysis of human glioblastoma specimens revealed that at least 25% of glioblastomas express elevated level of either PCFT or folate receptor (FOLR1). We conclude that the PCFT provides a mechanism for targeted delivery of drugs to some gliomas as a starting point for the development of efficient methods for treating gliomas with high expression of PCFT and/or FOLR1.

Differential expression of folate receptor 1 in medulloblastoma and the correlation with clinicopathological characters and target therapeutic potential.

Medulloblastoma is the most common malignant brain tumor in children. Folate receptor 1 (Folr1) was abundantly expressed in some epithelial malignancies. However the expression profile and the role of clinicopathological significance and therapeutic target potential in medulloblastoma still remain elusive. Currently we detected the expression of Folr1 in medulloblastoma and identified the diagnostic application by evaluating the clinical, pathological and neuroimaging values. Then we developed a target therapeutic compound with Folr1, which exhibited promising efficiency in treatment of medulloblastoma. Folr1 expression was up-regulated in medulloblastoma and positively correlated with percentage of Ki-67 and MMP9 labeling, pathological subtypes, serum Folr1 levels and CSF spreading on MRI. The level of serum Folr1 showed rational sensitivity and specificity in predicting histological subgroups. Strong Folr1 expression was recommended as the independent value regarding the prognosis of patients with medulloblastoma. Folr1 targeted therapy attenuated the tumor growth and metastasis with down-regulation of MMPs proteins and activation of apoptosis. Immunostaining analysis in the xenograft samples showed the decreased Ki-67 and MMP9 index providing the strong evidences that Folr1 targeted application can suppress the proliferation and invasion. Our findings uncovered in Folr1 a predictive candidate and therapeutic target for medulloblastoma.

Maternally Contributed Folate Receptor 1 Is Expressed in Ovarian Follicles and Contributes to Preimplantation Development.

Folates have been shown to play a crucial role for proper development of the embryo as folate deficiency has been associated with reduced developmental capacity such as increased risk of fetal neural tube defects and spontanous abortion. Transcripts encoding the reduced folate carrier RFC1 (SLC19A1 protein) and the high-affinity folate receptor FOLR1 are expressed in oocytes and preimplantation embryos, respectively. In this study, we observed maternally contributed FOLR1 protein during mouse and human ovarian follicle development, and 2-cell mouse embryos. In mice, FOLR1 was highly enriched in oocytes from primary, secondary and tertiary follicles, and in the surrounding granulosa cells. Interestingly, during human follicle development, we noted a high and specific presence of FOLR1 in oocytes from primary and intermediate follicles, but not in the granulosa cells. The distribution of FOLR1 in follicles was noted as membrane-enriched but also seen in the cytoplasm in oocytes and granulosa cells. In 2-cell embryos, FOLR1-eGFP fusion protein was detected as cytoplasmic and membrane-associated dense structures, resembling the distribution pattern observed in ovarian follicle development. Knock-down of Folr1 mRNA function was accomplished by microinjection of short interference (si)RNA targeting Folr1, into mouse pronuclear zygotes. This revealed a reduced capacity of Folr1 siRNA-treated embryos to develop to blastocyst compared to the siRNA-scrambled control group, indicating that maternally contributed protein and zygotic transcripts sustain embryonic development combined. In summary, maternally contributed FOLR1 protein appears to maintain ovarian functions, and contribute to preimplantation development combined with embryonically synthesized FOLR1.

Nanoparticle targeted folate receptor 1-enhanced photodynamic therapy for lung cancer.

OBJECTIVE: Despite modest improvements, the prognosis of lung cancer patients has still remained poor and new treatment are urgently needed. Photodynamic therapy (PDT), the use of light-activated compounds (photosensitizers) is a treatment option but its use has been restricted to central airway lesions. Here, we report the use of novel porphyrin-lipid nanoparticles (porphysomes) targeted to folate receptor 1 (FOLR1) to enhance the efficacy and specificity of PDT that may translate into a minimally-invasive intervention for peripheral lung cancer and metastatic lymph nodes of advanced lung cancer. MATERIALS AND METHODS: The frequency of FOLR1 expression in primary lung cancer and metastatic lymph nodes was first analyzed by human tissue samples from surgery and endobronchial ultrasonography-guided transbronchial needle aspiration (EBUS-TBNA). Confocal fluorescence microscopy was then used to confirm the cellular uptake and fluorescence activation in lung cancer cells, and the photocytotoxicity was evaluated using a cell viability assay. In vivo fluorescence activation and quantification of uptake were investigated in mouse lung orthotopic tumor models, followed by the evaluation of in vivo PDT efficacy. RESULTS: FOLR1 was highly expressed in metastatic lymph node samples from patients with advanced lung cancer and was mainly expressed in lung adenocarcinomas in primary lung cancer. Expression of FOLR1 in lung cancer cell lines corresponded with the intracellular uptake of folate-porphysomes in vitro. When irradiated with a 671nm laser at a dose of 10J/cm2, folate-porphysomes showed marked therapeutic efficacy compared with untargeted porphysomes (28% vs. 83% and 24% vs. 99% cell viability in A549 and SBC5 lung cancer cells, respectively). Systemically-administered folate-porphysomes accumulated in lung tumors with significantly enhanced disease-to-normal tissue contrast. Folate-porphysomes mediated PDT successfully inhibited tumor cell proliferation and activated tumor cell apoptosis. CONCLUSION: Folate-porphysome based PDT shows promise in selectively ablating lung cancer based on FOLR1 expression in these preclinical models.

Phototoxicity of Liposomal Zn- and Al-phthalocyanine Against Cervical and Oral Squamous Cell Carcinoma Cells In Vitro.

Background Material and Methods Results Conclusions.

Genetic Variation in Renal Expression of Folate Receptor 1 (Folr1) Gene Predisposes Spontaneously Hypertensive Rats to Metabolic Syndrome.

Metabolism of homocysteine and other sulfur amino acids is closely associated with metabolism of folates. In this study, we analyzed the possible role of folates and sulfur amino acids in the development of features of the metabolic syndrome in the BXH/HXB recombinant inbred strains derived from the spontaneously hypertensive rat (SHR) and Brown Norway progenitors. We mapped a quantitative trait locus for cysteine concentrations to a region of chromosome 1 that contains a cis-acting expression quantitative trait locus regulating mRNA levels of folate receptor 1 (Folr1) in the kidney. Sequence analysis revealed a deletion variant in the Folr1 promoter region of the SHR. Transfection studies demonstrated that the SHR-promoter region of Folr1 is less effective in driving luciferase reporter gene expression than the Brown Norway promoter region of Folr1. Results in the SHR.BN-chr.1 congenic strain confirmed that the SHR variant in Folr1 cosegregates with markedly reduced renal expression of Folr1 and renal folate reabsorption, decreased serum levels of folate, increased serum levels of cysteine and homocysteine, increased adiposity, ectopic fat accumulation in liver and muscle, reduced muscle insulin sensitivity, and increased blood pressure. Transgenic rescue experiments performed by expressing a Folr1 transgene in the SHR ameliorated most of the metabolic disturbances. These findings are consistent with the hypothesis that inherited variation in the expression of Folr1 in the kidney influences the development of the metabolic syndrome and constitutes a previously unrecognized genetic mechanism that may contribute to increased risk for diabetes mellitus and cardiovascular disease.

Folate-receptor 1 (FOLR1) protein is elevated in the serum of ovarian cancer patients.

OBJECTIVES: Ovarian cancer is the most lethal gynecological malignancy in North America. Although survival rates are high when the disease is diagnosed at an early stage, this decreases exponentially in late-stage diagnoses. As such, there is a need for novel early detection biomarkers. Through an integrated approach to ovarian cancer biomarker discovery that combines proteomics with transcriptomics and bioinformatics, our laboratory has identified folate-receptor 1 (FOLR1) and Dickkopf-related protein 3 (Dkk-3) as putative biomarkers. The objective of this study was to measure the levels of FOLR1 and Dkk-3 in the serum of patients with ovarian cancer, benign gynecological conditions and healthy women. DESIGN AND METHODS: FOLR1 and Dkk-3 were analyzed in serum of 100 ovarian cancer patients, 100 patients with benign gynecological conditions, and 100 healthy women using enzyme-linked immunosorbent assays (ELISAs). All specimens were analyzed in triplicate. RESULTS: FOLR1 was significantly elevated in the serum of ovarian cancer patients compared to serum of both healthy controls (P<0.0001) and patients with benign gynecological conditions (P<0.0001). Furthermore, FOLR1 was strongly correlated with CA125 as both were elevated in the serous histotype and in late-stage disease. FOLR1 did not outperform CA125 in receiver operating characteristic curve analysis and there was no significant complementarity between the two markers. Dkk-3 was not significantly different between the three serum cohorts and was not correlated with CA125. CONCLUSIONS: FOLR1 is a new biomarker for ovarian cancer which correlates closely with CA125. The role of FOLR1 in the pathogenesis of ovarian cancer warrants further investigation.

Biological effects of upregulated expression of transfected FOLR1 gene on SKOV3 cell lines acted by cisplatin / 中华妇产科杂志

Objective To explore biological effects of up-regulated expression of transfected FOLR1 gene on SKOV3 cell lines following action by cisplatin(DDP).Methods Three groups of cells originated from the same SKOV3 cell line were used in this research,including the SKOV3 cell line (blank control),the cell line transfected with lentiviral pWPI plasmid (no-load control) and the cell line transfected with FOLR1 gene via lentiviral pWPI plasmid (experimental group).Next,the mRNA and protein expression of FOLR1 gene in the three groups were detected by reverse transcription (RT)-PCR and western blot,respectively.Methyl thiazolyl tetrazolium (MTT) assay was used to analysis cells growth curve and identify their sensitivity to cisplatin,and their half inhibition concentration (IC5o) values were calculated.Based on the IC50 value (3.6 μg/ml) in the experimental group,different levels of cisplatin concentration (0.5 × IC50,1 × IC50,2 × IC50,respectively) were administered to the three groups of cells,and the inhibition rates,apoptosis rates as well as apoptosis proportion of each group after 24,48,72 hours were further recorded.Finally,the residual cisplatin concentrations in the three group cells acted successively by 1 × IC50 cisplatin for 48 hours were measured by high performance liquid chromatography(HPLC).P value less than 0.05 were defined as statistically significant.Results RT-PCR and western blot detection showed that stable mRNA and protein expression of the FOLR1 gene in the experimental group while the other two groups were not.MTT assay demonstrated that higher cell growth rate,sensitivity to cisplatin(IC50 =3.6 μg/ml) and inhibition rate in the experimental group compared with those in the other two groups (P ＜ 0.05),which showed no significance in intergroup comparison(P ＞ 0.05).Flow cytometry showed apoptosis rates among three groups increased with higher cisplatin concentrations and longer action duration in dosage-time dependent manner (P ＜ 0.05),and the proportion of S phase cells increased with higher cisplatin concentration in dosage-dependent manner (P ＜ 0.05) ; for the same concentration and duration,the experimental group showed significantly different apoptosis rates and S phase cells compared with the other two groups,which demonstrated no significance in intergroup comparison (P ＞ 0.05).After action by cisplatin(3.6 μg/ml) for 48 hours,HPLC showed significantly higher residual cisplatin concentration (2.60±0.21) μg/106 cell counts in experimental group than those in no-load control group (1.49 ±0.12) μg/106 cell counts and blank control group (1.54 ± 0.11)xg/106 cell counts,respectively (P ＜0.05),and the comparison within the latter two groups showed no significance (P ＞ 0.05).Conclusion Up-regulated expression of the transfected FOLR1 gene in SKOV3 cells may be associated with higher sensitivity to cisplatin,residual cisplatin concentration and higher proportion of S phase cells,and tended to inhibit cancer cells growth and induce apoptosis.