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ORIGINAL ARTICLE
Year : 2018  |  Volume : 14  |  Issue : 7  |  Page : 1540-1548

Selenocystine inhibits JEG-3 cell growth in vitro and in vivo by triggering oxidative damage-mediated S-phase arrest and apoptosis


1 Department of Orthopaedics, Taishan Hospital Affiliated to Taishan Medical University, Taian, Shandong, China
2 Department of Biochemistry, School of Basic Medicine, Taishan Medical University, Taian, Shandong, China
3 Department of Oncology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China

Date of Web Publication19-Dec-2018

Correspondence Address:
Zhigang Wei
324 Jingwuweiqi, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, Shandong
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jcrt.JCRT_864_17

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 > Abstract 


Background: Selenocystine (SeC) is a nutritionally available selenoamino acid presenting novel anticancer potential against human cancers. However, neither the effects nor mechanism of SeC against choriocarcinoma growth has been clarified yet. This study investigated the anticancer effects and mechanism of SeC against JEG-3 human choriocarcinoma growth in vitro and in vivo.
Materials and Methods: The in vitro anticancer efficiency was evaluated with cell viability, apoptosis, and oxidative stress. JEG-3 cell viability was determined with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Cell cycle distribution and apoptosis were examined by flow cytometric analysis. Oxidative damage was detected with immunofluorescence and western blotting. The in vivo anticancer efficiency was evaluated in immunodeficient mouse model of choriocarcinoma. The mechanism was also investigated.
Results: SeC dose and time dependently inhibited the viability of JEG-3 cells in vitro. The result of flow cytometry (FCM) analysis showed that obvious S-phase arrest and cell apoptosis were initiated by SeC in JEG-3 cells, which was further convinced by the decreased levels of cyclin A, poly-ADP-ribose polymerase cleavage, and activation of caspase-3,-7, and-9. In addition, SeC resulted in significant generation of reactive oxygen species (ROS) and superoxide anion, followed by the activation of DNA damage. However, SeC-induced oxidative damage and apoptosis were effectively blocked after ROS inhibition. Further investigation indicated that SeC effectively suppressed JEG-3 choriocarcinoma tumor xenograft growth in vivo. The mechanism may be the induction of cell apoptosis and oxidative damage through inhibiting cell proliferation (Ki-67) and angiogenesis (CD-31).
Conclusions: Our findings supported that human choriocarcinoma growth could be inhibited by SeC in vitro and in vivo through triggering oxidative damage-mediated S-phase arrest and apoptosis. Thus, SeC may be promising in the treatment of human choriocarcinoma.

Keywords: Apoptosis, choriocarcinoma, reactive oxygen species, selenocystine, S-phase arrest


How to cite this article:
Zhao M, Hou Y, Fu X, Li D, Sun J, Fu X, Wei Z. Selenocystine inhibits JEG-3 cell growth in vitro and in vivo by triggering oxidative damage-mediated S-phase arrest and apoptosis. J Can Res Ther 2018;14:1540-8

How to cite this URL:
Zhao M, Hou Y, Fu X, Li D, Sun J, Fu X, Wei Z. Selenocystine inhibits JEG-3 cell growth in vitro and in vivo by triggering oxidative damage-mediated S-phase arrest and apoptosis. J Can Res Ther [serial online] 2018 [cited 2019 Mar 21];14:1540-8. Available from: http://www.cancerjournal.net/text.asp?2018/14/7/1540/247731




 > Introduction Top


Choriocarcinoma has been derived from trophoblastic tissue, which was one of the most common malignant tumors in women, with high incidence and metastasis rate.[1],[2],[3] Patients with choriocarcinoma often suffered from anemia, infertility, cachexia, and even death.[4] Due to the aggressiveness of choriocarcinoma, surgical treatment has always been not appropriate.[4],[5] Hence, chemotherapy has been accepted as one of the most effective treatments for human choriocarcinoma.[1],[3] Therefore, exploring novel agents with high efficacy and low toxicity for the therapy of human choriocarcinoma is urgently needed.

Selenium (Se) is a trace element, which is significant for human and animal health.[6] Increasing epidemiological studies and clinical trials have reported the novel chemoprevention and chemotherapeutic effects of Se-containing compounds on human cancers, heart diseases, hypertension, diabetes, senile diseases, cataracts, liver and pancreatic diseases, infertility, Keshan disease, and anemia.[6],[7] Se intake in diet and serum Se level were negatively associated with the incidence of human lung cancer, prostate cancer, colorectal cancer, leukemia, and ovarian cancer.[6],[7],[8],[9],[10] Many evidences supported that Se-containing compounds could be applied as chemosensitizer for improving the therapeutic effects of chemotherapy drugs and reducing relevant side effects.[6],[7],[8],[9],[10] Selenocystine (SeC) has been a natural available selenoamino acid showing novel anticancer activities against human cancers.[7],[8] Multiple mechanisms were reported to contribute to the anticancer potential of SeC, including the induction of cell apoptosis and/or cell cycle arrest, the modulation of redox state, the detoxification of carcinogen, and the inhibition of angiogenesis.[7],[9],[10] However, the anticancer effects and mechanism of SeC against human choriocarcinoma have not been clarified yet.

In the present study, the anticancer activities and molecular mechanism of SeC against human choriocarcinoma were evaluated in vitro and in vivo. The results revealed that human choriocarcinoma cell growth could be significantly inhibited with SeC treatment both in vitro and in vivo. The mechanism may be the induction of S-phase arrest and apoptosis through triggering ROS-mediated DNA damage. Se-containing compounds may be promising in the chemoprevention and chemotherapy of human choriocarcinoma.


 > Materials and Methods Top


Chemicals

SeC, propidium iodide (PI), 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), and other reagents were all purchased from Sigma-Aldrich (St. Louis, MO, USA). BCA assay kit was obtained from Beyotime Company (Beijing, China). Dulbecco's Modified Eagle's medium (DMEM), fetal bovine serum (FBS), and penicillin–streptomycin were purchased from Invitrogen (Carlsbad, CA, USA). All the solvents involved were of high-performance liquid chromatography grade. The water applied in this study was supplied with a Milli-Q water purification system from Millipore. All antibodies, including cyclin A (cat. no. 4656S), cleaved poly-ADP-ribose polymerase (PARP) (cat. no. 9541), active caspase-3 (cat. no. 9664), active caspase-7 (cat. no. 9491), active caspase-9 (cat. no. 9501), Ser1981-ataxia telangiectasia mutated (ATM) (cat. no. 5883), Ser428-ataxia telangiectasia Rad3-related (ATR) (cat. no. 2853), Ser15-p53 (cat. no. 9284), total-p53 (cat. no. 9282), and β-actin (cat. no. 4970), were all obtained from Cell Signaling Technology (Beverly, MA, USA).

Cell culture

JEG-3 human choriocarcinoma cells were obtained from American Type Culture Collection (cat. no. HTB-36, ATCC, USA) and cultured in DMEM supplemented with 10% FBS, penicillin (100 U/ml), and streptomycin (100 U/ml) at 37°C in a humidified incubator under 5% CO2 atmosphere.

Detection of cell viability

Cell viability was detected with MTT assay. Briefly, JEG-3 cells (6 × 103 cells/well) were seeded in a 96-well plate and treated with SeC (0–40 μM) for 72 h, or cells were treated with 20 μM SeC for 12, 24, 48, and 72 h. After treatment, 20 μl MTT (5 mg/ml) was added and incubated for another 4 h. Then, the medium was removed, and 150 μl/well dimethyl sulfoxide was added to dissolve the formazan. Then, the absorbance at 570 nm was detected for indicating cell growth status. Cell viability was expressed as percentage of control (as 100%). Cell morphology was observed by a phase microscope (with a magnification of ×200).

Analysis of cell cycle and cell apoptosis

FCM was employed to analyze cell cycle distribution and cell apoptosis. Briefly, JEG-3 cells seeded in cell culture dishes were treated with 10, 20, and 40 μM SeC for 72 h. After treatment, cells were trypsinized and harvested by centrifugation. Then, cells were fixed with 70% ethanol overnight at −20°C and stained with PI solution. Labeled cells were washed and analyzed by FCM. The cell cycle proportions of G0/G1, S, and G2/M phases were analyzed by ModFit LT 4.0 software. The sub-G1 peak (hypodiploid DNA contents) was used to quantify the apoptotic cell death. About 104 cells/sample was recorded.

Detection of reactive oxygen species and superoxide anion

Intracellular ROS and superoxide anion levels were determined with dichlorodihydrofluorescein diacetate (DCFH-DA) and dihydroethidium (DHE) probes, respectively. In brief, JEG-3 cells (5 × 104 cells/well) were seeded in 6-cm plate and treated with 20 μM SeC for 0, 10, 30, and 60 min. After treatment, cells were incubated with 10 μM DCFH-DA or DHE for 15 min at 37°C in the dark. Then, cells were washed with PBS and imaged under a fluorescence microscope (with a magnification of ×100).

Western blotting

JEG-3 cells were seeded in 9-cm culture dishes and treated with indicated concentrations of SeC for 72 h. After treatment, cells were washed and lysed with RIPA lysis buffer. Total protein was extracted and quantified with BCA assay kit according to the manufacturer's instructions. The protein expression in JEG-3 cells was determined with western blotting. Briefly, protein was boiled for 10 min, loaded at 40 μg/lane, and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The proteins were transferred to polyvinylidene difluoride (PVDF) membrane and blocked with 5% bovine serum albumin for 2 h at room temperature. The PVDF membrane was incubated with primary antibodies (1:1000) overnight at 4°C and then secondary antibodies (1:2000) for 2 h at room temperature. Protein bands were developed with X-ray film using an enhanced chemiluminescence system (Nikon). The band of β-actin was employed as positive control.

In vivo study

Thirty female nude mice were divided into three groups. After adaptation for 1-week, JEG-3 cells (107 cells in 100 μl serum-free medium) were subcutaneously injected into the left oxter of mice. After growing for 7 days (tumor volume was about 60 mm 3), the mice were administrated with SeC. Group 1 was set as the control group without treatment and Groups 2 and 3 were administrated with 5 and 10 mg/kg of SeC, respectively. SeC was injected from the caudal vein every other day for 14 days (a total of eight times). After administration was completed, tumors were harvested and measured with the following formula: volume = l × w2/ 2, thereinto l was the maximal length and w was the width. Part of the tumor tissue was cut into 4-μm slice and analyzed with immunohistochemical (IHC) staining. The part of tumors was applied for western blotting assay. The animal experiments were generally conducted according to the demonstration of previous report.[11] All animal experiments were reviewed and approved by the Animal Experimentation Ethics Committee.

Statistical analysis

Statistical analysis was performed with the SPSS statistical package (SPSS 13.0 for Windows; SPSS, Inc., Chicago, IL USA). The difference between two groups was analyzed with a two-tailed Student's t-test. The difference between three or more groups was analyzed by one-way analysis of variance multiple comparison. Difference with P < 0.05 (*) or P < 0.01 (**) was considered statistically significant. Bars in the figures with different characters indicated statistically difference at the P < 0.05 level.


 > Results Top


Selenocystine inhibits JEG-3 cell growth in vitro

The in vitro cytotoxicity of SeC toward JEG-3 cells was screened with MTT assay. The result suggested that JEG-3 cell growth could be dose and time dependently inhibited with SeC treatment [Figure 1]. Specifically, for the cells exposed to 10, 20, and 40 μM SeC for 72 h, the cell viability was significantly decreased from control (100%) to 63.5, 40.3, and 18.6%, respectively. For the cells treated with 20 μM SeC for 24, 48, and 72 h, the cell viability was significantly inhibited to 82.2, 57.4, and 39.2%, respectively. This cytotoxic effect of SeC on JEG-3 cells was further confirmed by the cell morphological changes, such as cell shrinkage, reduced cell number, and lost cell-to-cell contact. The results suggested that SeC could be applied as a cytotoxic agent in inhibiting growth of JEG-3 human choriocarcinoma.
Figure 1: Selenocystine inhibits JEG-3 cell growth in vitro. (a) Dose-dependent inhibition of selenocystine against JEG-3 cell growth. Cells (6 × 103 cells/well) were seeded in 96-well plate and treated with 0–40 μM selenocystine for 72 h. (b) Time-dependent inhibition of selenocystine against JEG-3 cell growth. Cells were treated with 20 μM selenocystine for 12, 24, 48, and 72 h. Cell viability was detected with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. (c) Morphological changes. Cells were treated with 20 μM selenocystine for 72 h, and the cell morphology was observed under an inverted phase microscope (×200)

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Selenocystine induces S-phase arrest and apoptosis

To explore the cell death mechanism, cell cycle distribution and apoptosis in SeC-treated JEG-3 cells were examined with FCM. The results suggested that significant S-phase arrest and apoptosis were observed after SeC treatment [Figure 2]a. For instance, after treating JEG-3 cells with 10 and 20 μM SeC for 72 h, S-phase arrest could be obviously induced from 17.8% (control) to 39.5 and 48.2%, respectively. The SeC-induced S-phase arrest has also been convinced with statistical results of cell cycle distribution [Figure 2]b. Cyclin A was a key regulator of S-phase,[12],[13] which was also examined. As shown in [Figure 2]c and [Figure 2]d, SeC treatment apparently inhibited cyclin A expression in dose- and time-dependent manner. These results clearly demonstrated that SeC caused S-phase arrest in JEG-3 human choriocarcinoma cells. In addition, 20 μM of SeC also triggered slight cell apoptosis (9.8%) as convinced by the increase of sub-G1 peak, which was usually employed to quantify the apoptotic cell death.[14] However, SeC treatment (40 μM) resulted in markedly cell apoptosis to 88.7% [Figure 2]a and [Figure 2]e. The apoptotic mechanism induced by SeC was further investigated. PARP cleavage and caspase activation, two important apoptotic events, were detected in SeC-treated choriocarcinoma JEG-3 cells [Figure 2]f. SeC treatment obviously induced the PARP cleavage and the activation of caspase-3, caspase-7, and caspase-9 with a dose-dependent manner. The SeC-induced apoptosis in JEG-3 human choriocarcinoma cells could be further validated.
Figure 2: Selenocystine induces S-phase arrest and apoptosis in JEG-3 cells. (a) Cell apoptosis and cell cycle distribution. Cells were seeded in 6-well plate and treated with 10, 20, and 40 μM selenocystine for 72 h. Then cells were collected, stained with propidium iodide solution, and examined by flow cytometry. (b) Statistic analysis of cell cycle distribution. Dose-dependent (c) and time-dependent (d) effects of selenocystine on cyclin A expression. The protein expression was detected by western blotting. (e) Statistic analysis of cell apoptosis. (f) Effects of selenocystine on cell apoptosis markers

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Selenocystine triggers oxidative damage in JEG-3 cells

Previous studies have demonstrated that human cancer cell apoptosis could be induced by SeC through triggering ROS-mediated oxidative damage.[10] In the present study, the oxidative status in SeC-treated JEG-3 cells was also evaluated. First, the ROS and superoxide anion were measured by DCFH-DA and DHE probes, respectively. As shown in [Figure 3]a, treatment with SeC (20 μM) leads to time-dependent increase of intracellular ROS and superoxide anion, as indicated by the enhanced green and red fluorescence, respectively. The accumulation of ROS and superoxide anion was determined as early as within 10 min. This result supported the significant role of ROS as an early event in drug-induced apoptosis. To further clarify the SeC-induced oxidative damage, several DNA damage markers in the DNA damage-signaling axis were also determined.[15],[16],[17] As shown in [Figure 3]b, SeC dose dependently triggered the phosphorylation activation of ATM (Ser1981), ATR, Ser15-p53, and Ser139-histone. Sec also time dependently activated Ser15-p53 and Ser139-histone, further confirming the SeC-induced oxidative damage [Figure 3]c. Taken together, above results indicated that ROS-mediated oxidative damage could be triggered by SeC in JEG-3 human choriocarcinoma cells in vitro.
Figure 3: Selenocystine triggers oxidative damage in JEG-3 cells. (a) Selenocystine caused reactive oxygen species and superoxide anion production. Cells were seeded in 6-well plate and treated with 20 μM selenocystine for 10, 30, and 60 min. After treatment, cells were preincubated with 10 μM dichlorodihydrofluorescein diacetate or dihydroethidium probe for detection of reactive oxygen species and superoxide anion, respectively. (b) Dose-dependent effects of selenocystine on DNA damage markers. Cells were treated with 0–40 μM selenocystine for 72 h. (c) Time-dependent effects of selenocystine on DNA damage markers. The protein expression was examined by western blotting method

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Roles of reactive oxygen species in Selenocystine-induced apoptosis in JEG-3 cells

Based on the significant roles of ROS in SeC-induced apoptosis, ROS scavenger, glutathione (GSH) was applied for further confirmation. As shown in [Figure 4]a, SeC treatment (10 and 20 μM) both significantly inhibited JEG-3 cell growth. However, SeC-induced cell growth inhibition could be effectively attenuated after pretreatment of cells with 5 mM GSH for 2 h. This tendency was further confirmed with improved cell morphology [Figure 4]b. In addition, ROS inhibition by GSH also suppressed SeC-induced caspase-3 activation [Figure 4]c, indicating attenuated SeC-induced cell apoptosis. Moreover, the molecular mechanism after ROS inhibition was also explored. As shown in [Figure 4]d, GSH pretreatment dramatically suppressed SeC-induced PARP cleavage, caspase-3 activation, and Ser15-p53 phosphorylation. Meanwhile, the cyclin A expression was also recovered after the supplement of GSH. Taken together, these results powerfully proved that SeC induced cytotoxicity and apoptosis in JEG-3 cells with ROS-dependent manner.
Figure 4: The inhibition of reactive oxygen species suppresses selenocystine-induced cytotoxicity and apoptosis in JEG-3 cells. (a) Reactive oxygen species inhibition attenuated selenocystine-induced cytotoxicity. (b) Reactive oxygen species inhibition improved cell morphology in selenocystine-treated JEG-3 cells. Cells were pretreated with 5 mM glutathione for 2 h before selenocystine treatment. (c) Glutathione supplement blocked selenocystine-induced apoptosis in JEG-3 cells. Cells were pretreated with 5 mM glutathione for 2 h before selenocystine treatment. Cell apoptosis was detected by flow cytometry. (d) Reactive oxygen species elimination attenuated selenocystine-induced oxidative damage, S-phase arrest, and apoptosis

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Selenocystine attenuates choriocarcinoma tumor xenograft growth in vivo

To validate the in vivo anticancer effects and mechanism, the immunodeficiency nude mice bearing JEG-3 human choriocarcinoma cells were employed. The results showed that SeC treatment in vivo significantly inhibited tumor growth [Figure 5]a and tumor weight [Figure 5]b. Mechanically, cell apoptosis and oxidative damage could also be triggered with SeC treatment in vivo, as convinced by the activation of casspase-3, Ser15-p53, and Ser139-histone [Figure 5]c. Then, the cell proliferation and angiogenesis in vivo were also evaluated by the IHC method, and the results indicated that SeC treatment apparently inhibited both cell proliferation (Ki-67 staining) and angiogenesis (CD-31 staining) in vivo [Figure 5]d. These results all revealed that SeC was able to inhibit JEG-3 cell growth in vivo by triggering oxidative damage-mediated apoptosis involving antiproliferation and antiangiogenesis.
Figure 5: Selenocystine attenuates the growth of choriocarcinoma tumor xenografts in vivo. Selenocystine inhibits tumor volume (a) and tumor weight (b). JEG-3 cells (107 cells) were injected subcutaneously in nude mice. After growing for 1 week, the mice were administrated selenocystine at 5 and 10 mg/kg. The tumor volume and weight were measured at the end of the experiment. (c) Selenocystine induced apoptosis and oxidative damage in vivo. The protein expression was assayed by western blotting. (d) Selenocystine abolished the cell proliferation and angiogenesis in vivo. The Ki-67 and CD-31 expressions in vivo were examined with immunohistochemical method

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 > Discussion Top


Human choriocarcinoma has been one common malignant tumor in female, with high aggressiveness and recurrence rate.[18] Current treatment strategies were mainly based on cytotoxic drugs, which also made obvious cytotoxic effects on healthy cells.[19],[20] Exploring novel and efficient drugs to inhibit the growth of choriocarcinoma have been an urgent problem in clinic.[18],[19] SeC is a nutritionally available selenoamino acid, showing novel anticancer activities against human cancers, such as lung cancer, breast cancer, and glioma.[8],[9],[10] However, the ability of SeC for choriocarcinoma has not been elucidated. Hence, the anticancer effects and mechanism of SeC against JEG-3 cells in vitro and in vivo were investigated. The results indicated that SeC could inhibit JEG-3 cell growth in vitro and in vivo. The mechanism was the induction of S-phase arrest and apoptosis through triggering ROS-mediated oxidative damage.

Apoptosis is a programmed cell death involving multiple apoptotic pathways, through which the aging and dead cells would be removed to maintain and stabilize the homeostasis.[21],[22],[23],[24] Induction of cancer cell apoptosis with cytotoxic drugs is the most important way in treating human tumors. Mitochondrial pathway, endoplasmic reticulum pathway, and death receptor pathway all contributed to drug-induced cancer cell apoptosis.[11],[25] Furthermore, drug-induced cell cycle arrest has also one of the most effective strategies for blocking cell cycle. Cyclin is a kind of key molecules that control the coordinated DNA synthesis, chromosome separation, and cell division.[26] Cyclin A functioned as a positive regulator of the cell cycle, which was mainly detected in the S and M phases. Cyclin A can form a complex with CDK2 to regulate cells to enter the mitosis.[27],[28],[29] In the present study, SeC could induce S-phase arrest by blocking cyclin A expression in JEG-3 cells. Moreover, JEG-3 cells exposed to SeC also showed significant apoptotic features, such as cell shrinkage, apoptotic body formation, PARP cleavage, and caspase activation. These results indicated that induction of S-phase arrest and apoptosis both contributed to SeC-induced cell growth inhibition against JEG-3 cells.

The balance of redox status would be disturbed by the overproduced ROS and superoxide, which would make negative effects on the normal life activities.[30],[31],[32] ROS-mediated DNA damage belonged to oxidative damage, which has been supported by many previous publications.[10],[11],[30] Induction of oxidative damage in cancer cells was accepted as one of the effective treatment strategies.[33] ROS, including hydrogen peroxide, hydroxyl radical, superoxide anion, and so on, all played important roles in inducing cancer cell apoptosis, regulating cell signaling and maintaining cell homeostasis.[34],[35] The intracellular level of ROS has been maintained by the balance of the anti-antioxidant and pro-antioxidant system. It is well known that ROS was one of the main mechanisms of cellular damage, which was involved in cancer, inflammation, and so on.[21],[24] Therefore, induction of cell apoptosis by promoting ROS accumulation has been one important mechanism for treating human cancers.

Many chemotherapy drugs inhibit tumor growth by inducing ROS a cumulation and further DNA damage. In the present study, significant ROS and superoxide accumulation was observed in JEG-3 cells treated with SeC. As expected, ROS generation subsequently leads to DNA damage, as demonstrated by the phosphorylation activation of Ser1981-ATM, Ser428-ATR, Ser15-p53, and Ser139-histone. The p53 was a cell cycle checkpoint protein which can block DNA synthesis, arrest cell cycle progress, and inhibit cell division to maintain genetic stability.[17],[36],[37] ATM was the main switch molecules that directly identify DNA double-strand breaks and initiate DNA damage signaling pathways.[38],[39],[40],[41] ATR was a serine-threonine protein kinase that responded to DNA damage, and some proteins would be phosphorylated to initiate DNA repair signals.[42],[43],[44] However, GSH supplement effectively inhibited ROS-mediated DNA damage, attenuated S-phase arrest, and apoptosis. We speculated that Se may be incorporated into the peptides of Se-containing enzymes, such as GSH peroxidase and thioredoxin reductase. Therefore, the antioxidant system would be disturbed and then induced ROS-mediated oxidative damage and cancer cell apoptosis. Hence, ROS, as the upstream apoptosis-inducing factor, plays important roles in triggering cell apoptosis. The inhibition of ROS accumulation by GSH could effectively inhibit SeC-induced DNA damage and apoptosis. Therefore, SeC-inhibited JEG-3 cell growth by induction of S-phase arrest and cell apoptosis was believed to a ROS-dependent manner.


 > Conclusions Top


Our results revealed that SeC could inhibit human choriocarcinoma growth in vitro and in vivo by induction of S-phase arrest and apoptosis through trigging ROS-mediated DNA damage.

Financial support and sponsorship

The study was supported by Natural Science Foundation of Shandong No. ZR2015HL050 to D.-W. Li.

Conflicts of interest

There are no conflicts of interest.



 
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