Jinlu Shan

Nanogold-enwrapped graphene nanocomposites as trace labels for sensitivity enhancement of electrochemical immunosensors in clinical immunoassays: Carcinoembryonic antigen as a model.

A new, highly sensitive electrochemical immunosensor with a sandwich-type immunoassay format was designed to quantify carcinoembryonic antigen (CEA), as a model tumor marker, using nanogold-enwrapped graphene nanocomposites (NGGNs) as trace labels in clinical immunoassays. The device consisted of a glassy carbon electrode coated with Prussian Blue (PB) on whose surface gold nanoparticles were electrochemically deposited to the further modified with the specific analyte-capturing molecule, anti-CEA antibodies. The immunoassay was performed using horseradish peroxidase (HRP)-conjugated anti-CEA as secondary antibodies attached on the NGGN surface (HRP-anti-CEA-NGGN). The method using HRP-anti-CEA-NGGNs as detection antibodies shows high signal amplification, and exhibits a dynamic working range of 0.05-350 ng/mL with a low detection limit of 0.01 ng/mL CEA (at 3s). The assayed results of serum samples with the sensor received an acceptable agreement with the reference values. Importantly, the methodology provides a promising ultrasensitive assay strategy for clinical applications.

MicroRNA-224 is upregulated in HepG2 cells and involved in cellular migration and invasion.

Background and Aim:  MicroRNAs are a class of small non‐coding RNAs that negatively regulate the expression of their target genes. The aim of the present study was to explore the effects of microRNA on biological behaviors of HepG2 cells and further analyze its characteristics.

CALIFORNIUM-252 BRACHYTHERAPY COMBINED WITH EXTERNAL-BEAM RADIOTHERAPY FOR CERVICAL CANCER: LONG-TERM TREATMENT RESULTS

PURPOSE To observe, by retrospective analysis, the curative effects and complications due to californium-252 (252Cf) neutron intracavitary brachytherapy (ICBT) combined with external-beam radiotherapy (EBRT) in the treatment of cervical cancer. METHODS AND MATERIALS From February 1999 to December 2007, 696 patients with cervical cancer (Stages IB to IIIB) were treated with 252Cf-ICBT in combination of EBRT. Of all, 31 patients were at Stage IB, 104 at IIA, 363 at IIB, 64 at IIIA, and 134 at IIIB. Californium-252 ICBT was delivered at 7-12 Gy per insertion per week, with a total dose of 29-45 Gy to reference point A in three to five insertions. The whole pelvic cavity was treated with 8-MV X-ray external irradiation at 2 Gy per fraction, four times per week. After 16-38 Gy of external irradiation, the center of the whole pelvic field was blocked with a 4-cm-wide lead shield, with a total external irradiation dose of 44-56 Gy. The total treatment course was 5 to 6 weeks. RESULTS Overall survival rate at 3 and 5 years for all patients was 76.0% and 64.9%, respectively. Disease-free 3- and 5-year survival rates of patients were 71.2% and 58.4%, respectively. Late complications included vaginal contracture and adhesion, radiation proctitis, radiation cystitis, and inflammatory bowel, which accounted for 5.8%, 7.1%, 6.2%, and 4.9%, respectively. Univariate analysis results showed significant correlation of stage, age, histopathologic grade, and lymph node status with overall survival. Cox multiple regression analysis showed that the independent variables were stage, histopathologic grade, tumor size, and lymphatic metastasis in all patients. CONCLUSION Results of this series suggest that the combined use of 252Cf-ICBT with EBRT is an effective method for treatment of cervical cancer.

Human apurinic/apyrimidinic endonuclease 1 translocalizes to mitochondria after photodynamic therapy and protects cells from apoptosis

Photodynamic therapy (PDT) is an effective therapeutic regime for lung cancer. Mitochondrial functional failure is considered to be one of the most important factors causing cell death after PDT. However, the detailed mechanisms that are involved are still unclear. We previously reported that apurinic/apyrimidinic endonuclease (APE1) plays a critical role in regulating sensitivity to PDT in the lung cancer A549 cell line. An important mitochondrial regulatory role for APE1 has recently been reported, so therefore we explored the role of APE1 in cell survival after PDT‐induced oxidative stress through regulation of mitochondrial function. We first observed that photoirradiation induced the mitochondrial translocation of APE1. The ability of APE1 to regulate mitochondrial membrane potential and reactive oxygen species (ROS) production after photoirradiation was tested in APE1 knockdown A549 cells. APE1‐deficient A549 cells were characterized as having a lower mitochondrial membrane potential and higher ROS production, which led to increased apoptosis through the mitochondrial pathway after PDT. Additionally, unexpected activity of APE1 was observed in mitochondria: the control of mitochondrial transcriptional activity by redox regulation of mitochondrial transcription factor A (TFAM). Furthermore, two dominant‐negative mutants of APE1 were overexpressed to enhance their individual activities in mitochondria. The results suggest that both these APE1 activities play a role in the regulation of mitochondrial function but through different mechanisms. The present study not only provides possible mechanisms for APE1 in regulating survival after photoirradiation but also uncovers a new activity of APE1 in mitochondria. (Cancer Sci 2012; 103: 882–888)

Small-molecule BH3 mimetic and pan-Bcl-2 inhibitor AT-101 enhances the antitumor efficacy of cisplatin through inhibition of APE1 repair and redox activity in non-small-cell lung cancer.

AT-101 is a BH3 mimetic and pan-Bcl-2 inhibitor that has shown potent anticancer activity in non-small-cell lung cancer (NSCLC) in murine models, but failed to show clinical efficacy when used in combination with docetaxel in NSCLC patients. Our recent study has demonstrated that AT-101 enhanced the antitumor effect of cisplatin (CDDP) in a murine model of NSCLC via inhibition of the interleukin-6/signal transducer and activator of transcription 3 (STAT3) pathway. This study explored the underlying mechanisms for the enhanced anticancer activity of CDDP by AT-101. Our results show that, when compared with monotherapy, AT-101 significantly enhanced the inhibitory effects of CDDP on proliferation and migration of A549 cells and on tube formation and migration in human umbilical vein endothelial cells. AT-101 promoted the proapoptotic activity of CDDP in A549 cells. AT-101 also enhanced the inhibitory effect of CDDP on DNA repair and redox activities of apurinic/apyrimidinic endonuclease 1 (APE1) in A549 cells. In tumor tissues from nude mice treated with AT-101 plus CDDP or monotherapy, the combination therapy resulted in greater inhibition of angiogenesis and tumor cell proliferation than the monotherapy. These results suggest that AT-101 can enhance the antitumor activity of CDDP in NSCLC via inhibition of APE1 DNA repair and redox activities and by angiogenesis and induction of apoptosis, but other mechanisms cannot be excluded. We are now conducting a Phase II trial to examine the clinical efficacy and safety profile of combined use of AT-101 plus CDDP in advanced NSCLC patients.

Sequential treatment with AT-101 enhances cisplatin chemosensitivity in human non-small cell lung cancer cells through inhibition of apurinic/apyrimidinic endonuclease 1-activated IL-6/STAT3 signaling pathway

AT-101, known as R-(–)-gossypol, is a potent anticancer agent, but its chemosensitizing effects remain elusive. The present study aimed to examine whether AT-101 could increase the sensitivity of non-small cell lung cancer A549 cells to cisplatin (CDDP) and the underlying mechanisms. We evaluated the efficacy of the sequential treatment with AT-101 and CDDP using both in vitro and in vivo models. Our results showed that as compared to AT-101 or CDDP monotherapy, or AT-101 plus CDDP concurrent treatment, the sequential treatment significantly inhibited cell proliferation and migration and induced tumor cell death. Moreover, the efficacy of the sequential treatment was also confirmed in a mouse A549 xenograft model. Our study revealed that AT-101 inhibited the reduced status of apurinic/apyrimidinic endonuclease 1 (APE1) and attenuated APE1-mediated IL-6/STAT3 signaling activation by decreasing IL-6 protein expression; suppressing the STAT3–DNA binding; and reducing the expression of the downstream antiapoptotic proteins Bcl-2 and Bcl-xL. In conclusion, AT-101 enhances the sensitivity of A549 cells to CDDP in vitro and in vivo through the inhibition of APE1-mediated IL-6/STAT3 signaling activation, providing a rationale for the combined use of AT-101 and CDDP in non-small cell lung cancer chemotherapy.

Apurinic/apyrimidinic endonuclease 1 regulates angiogenesis in a transforming growth factor β-dependent manner in human osteosarcoma

Angiogenesis plays an important role in tumor growth and metastasis and has been reported to be inversely correlated with overall survival of osteosarcoma patients. It has been shown that apurinic/apyrimidinic endonuclease 1 (APE1), a dually functional protein possessing both base excision repair and redox activities, is involved in tumor angiogenesis, although these mechanisms are not fully understood. Our previous study showed that the expression of transforming growth factor β (TGFβ) was significantly reduced in APE1‐deficient osteosarcoma cells. Transforming growth factor β promotes cancer metastasis through various mechanisms including immunosuppression, angiogenesis, and invasion. In the current study, we initially revealed that APE1, TGFβ, and microvessel density (MVD) have pairwise correlation in osteosarcoma tissue samples, whereas TGFβ, tumor size, and MVD were inversely related to the prognosis of the cohort. We found that knocking down APE1 in osteosarcoma cells resulted in TGFβ downregulation. In addition, APE1‐siRNA led to suppression of angiogenesis in vitro based on HUVECs in Transwell and Matrigel tube formation assays. Reduced secretory protein level of TGFβ of culture medium also resulted in decreased phosphorylation of Smad3 of HUVECs. In a mouse xenograft model, siRNA‐mediated silencing of APE1 downregulated TGFβ expression, tumor size, and MVD. Collectively, the current evidence indicates that APE1 regulates angiogenesis in osteosarcoma by controlling the TGFβ pathway, suggesting a novel target for anti‐angiogenesis therapy in human osteosarcoma.

Serum APE1 as a predictive marker for platinum-based chemotherapy of non-small cell lung cancer patients

Purpose To define the role of the DNA repair protein apurinic/apyrimidinic endonuclease 1 (APE1) in predicting the prognosis and chemotherapeutic response of non-small cell lung cancer patients receiving platinum-containing chemotherapy. Results Our investigations found that serum APE1 level was significantly elevated in 229 of 412 NSCLC patients and correlated with its level in tissue (r2 = 0.639, p < 0.001). The elevated APE1 level in both tissue and serum of patients prior to chemotherapy was associated with worse progression-free survival (HR: 2.165, p < 0.001, HR: 1.421, p = 0.012), but not with overall survival. After 6 cycles of chemotherapy, a low APE1 serum level was associated with better overall survival (HR: 0.497, p = 0.010). Experimental Design We measured APE1 protein levels in biopsy tissue from 172 NSCLC patients and sera of 412 NSCLC patients receiving platinum-based chemotherapy by immunohistochemistry and a newly established sensitive and specific enzyme-linked immunosorbent assay, respectively. APE1 levels in sera of 523 healthy donors were also determined as control. Conclusions Our studies indicate that APE1 is a biomarker for predicting prognosis and therapeutic efficacy in NSCLC. The chemotherapy-naïve serum APE1 level, which correlated with its tissue level inversely associated with progression-free survival of platinum-containing doublet chemotherapy, whereas post-treatment serum APE1 level was inversely associated with overall survival.

APE1 promotes antioxidant capacity by regulating Nrf-2 function through a redox-dependent mechanism.

APE1 is a multifunctional protein that has recently been implicated in protecting cells from oxidative stress. In the current study, we confirmed that APE1׳s effect on cellular antioxidant capacity is related to its redox activity through the use of an APE1 functional mutant, and we investigated the mechanism through which this multifunctional protein affects the function of the transcription factor Nrf-2 in regulating oxidative stress-induced genes. Using a pair of mutants for both the redox activity and the acetylation-regulated activity of APE1, in vitro assays showed that the redox activity of APE1 is crucial for its nuclear association with Nrf-2 and subsequent activation of Nrf-2׳s transcription of several downstream genes during oxidative challenge. Important oxidative stress genes are affected by APE1 redox activity, including Hmox1, Gstm1, and Txnrd1. In addition, utilizing human non-small-cell lung cancer sample tissue as well as a nude mouse xenograft model, we determined that APE1 expression levels are inversely correlated to oxidative stress in vivo. These findings indicated that interference with these crucial functions of APE1 shows promise in preventing resistance to certain radiotherapies and that further research is necessary to understand APE1׳s complex roles in regulating both the basal redox status and the oxidative stress state of the cellular environment.

A population‐based study elicits a reverse correlation between age and overall survival in elderly patients with rectal carcinoma receiving adjuvant chemotherapy

Colorectal cancer is the third most common cancer and the fourth most common cause of cancer‐related death globally. This population‐based study aimed to explore the predictive factors that affected the overall survival of rectal cancer patients receiving adjuvant chemotherapy plus radical surgery using a Cox proportional hazards modeling approach. A total of 619 patients with rectal cancer who underwent surgery were enrolled between October 2006 and May 2013. Clinical characteristics of the patients were compared among the groups and potential prognostic factors were analyzed using the spss program, version 19.0. Patients aged ≥ 70 years have distinctive characteristics such as lager tumour size (≥ 5 cm), damaged micturition and higher incidence of diabetes compared to younger and middle‐aged patients. Male gender, tumour size (≥ 5 cm), poor differentiation, later stage, adjuvant chemotherapy, damaged micturition, hypertension or diabetes are associated with a worse prognosis for rectal cancer patients (P < 0.05). However, smoking is a favourable factor to the patients (P = 0.018). Age of ≥ 70 years is an independent prognostic factor for patients with rectal cancer after surgery (P = 0.000) and elderly patients with Stage II and III disease receiving adjuvant chemotherapy show a favourable prognosis. The elderly patients who suffered from diabetes receiving adjuvant chemotherapy have a poor prognosis. Further prospective and large population studies are warranted to confirm the findings of this study.