Wenxin Qin

The Growth and Metastasis of Human Hepatocellular Carcinoma Xenografts Are Inhibited by Small Interfering RNA Targeting to the Subunit ATP6L of Proton Pump

Extracellular pH is usually low in solid tumors, in contrast to the approximately neutral intracellular pH. V-ATPase, which overly functions in some cancers with metastatic potential, plays an important role in maintaining neutral cytosolic pH, very acidic luminal pH, and acidic extracellular pH. ATP6L, the 16 kDa subunit of proton pump V-ATPase, can provide proton hydrophilic transmembrane path. In this study, ATP6L in a human hepatocellular carcinoma cell line with highly metastatic potential (HCCLM3) was knocked down using DNA vector-based small interfering RNA (siRNA) to suppress the metastasis. The expression of ATP6L in stable siRNA transfectants, designated as si-HCCLM3 cells, was inhibited by approximately 60%. The proton secretion and the intracellular pH recovery from NH4Cl-prepulsed acidification were inhibited in si-HCCLM3 cells. The invasion of the si-HCCLM3 cells was suppressed in vitro; simultaneously, the expressions of matrix metalloproteinase-2 and gelatinase activity were reduced. In vivo, at 35th day after implantation of the si-HCCLM3 xenografts into the livers in BalB/c (nu+/nu+) mice, the size of liver tumor tissues was dramatically smaller in siRNA group than in the controlled group. The most impressing effect of ATP6L siRNA is its striking reduction of the metastatic potential of HCCLM3 cells. In control, all eight mice had the intrahepatic metastasis and six of eight the pulmonary metastasis, whereas in ATP6L siRNA-treated group, three of eight had the intrahepatic metastasis and only one of eight the pulmonary metastasis. The results suggest that the inhibition of V-ATPase function via knockdown of ATP6L expression using RNA interfering technology can effectively retard the cancer growth and suppress the cancer metastasis by the decrease of proton extrusion and the down-regulation of gelatinase activity.

Hsa_circ_0001649: A circular RNA and potential novel biomarker for hepatocellular carcinoma

BACKGROUND It has been shown that circular RNA (circRNA) is associated with human cancers, however, few studies have been reported in hepatocellular carcinoma (HCC). OBJECTIVE To estimate clinical values of a circular RNA, Hsa_circ_0001649, in HCC. METHODS Expression level of hsa_circ_0001649 was detected in HCC and paired adjacent liver tissues by real-time quantitative reverse transcription-polymerase chain reactions (qRT-PCRs). Differences in expression level of hsa_circ_0001649 were analyzed using the paired t-test. Tests were performed between clinical information and hsa_circ_0001649 expression level by analysis of variance (ANOVA) or welch t-test and a receiver operating characteristics (ROC) curve was established to estimate the value of hsa_circ_0001649 expression as a biomarker in HCC. RESULTS hsa_circ_0001649 expression was significantly downregulated in HCC tissues (p = 0.0014) based on an analysis of 89 paired samples of HCC and adjacent liver tissues and the area under the ROC curve (AUC) was 0.63. Furthermore, hsa_circ_0001649 expression was correlated with tumor size (p = 0.045) and the occurrence of tumor embolus (p = 0.017) in HCC. CONCLUSIONS We first found hsa_circ_0001649 was significantly downregulated in HCC. Our findings indicate hsa_circ_0001649 might serve as a novel potential biomarker for HCC and may function in tumorigenesis and metastasis of HCC.

Elevated expression of DKK1 is associated with cytoplasmic/nuclear β-catenin accumulation and poor prognosis in hepatocellular carcinomas

BACKGROUND/AIMS To assess the value of Dickkopf-1 (DKK1) for predicting clinical outcome of human hepatocellular carcinoma (HCC) in patients with HCC. METHODS Expression of DKK1 and beta-catenin was investigated in HCC cell lines using qRT-PCR, Western blotting and immunofluorescence. Tissue microarrays representing 314 HCC patients were used to determine the expression patterns of DKK1 and beta-catenin by immunohistochemistry, and prognostic significance was assessed by using Kaplan-Meier survival estimates and log-rank tests. RESULTS The expression level of DKK1 was associated with the staining pattern of beta-catenin in HCC cell lines, and DKK1 overexpression correlated with beta-catenin cytoplasmic/nuclear accumulation in clinical HCC samples (P=0.011, correlation coefficient=0.144). High DKK1 expression predicted unfavorable prognosis in HCC patients, especially in early stage patients and those with normal AFP levels. In multivariate analyses, DKK1 was an independent predictor for overall survival (OS) (P=0.002) and disease-free survival (DFS) (P=0.002) of HCC patients. Furthermore, the HCC patients with high DKK1 expression and cytoplasmic/nuclear beta-catenin accumulation had very poor prognosis. CONCLUSIONS Elevated expression of DKK1 is a critical event in patients with HCC that indicates poor clinical outcome. DKK1, alone or combined with beta-catenin, is a novel prognostic predictor for HCC patients.

CD24 Is a Novel Predictor for Poor Prognosis of Hepatocellular Carcinoma after Surgery

Purpose: To investigate the role of CD24 in tumor invasion and prognostic significance in hepatocellular carcinoma (HCC). Experimental Design: CD24 expression was measured in stepwise metastatic HCC cell lines, tumor, peritumoral tissues, and normal liver tissues by quantitative real-time PCR and Western blot. The role of CD24 in HCC was investigated by CD24 depletion using small interfering RNA. Tumor tissue microarrays of 314 HCC patients who underwent resection between 1997 and 2000 were used to detect expression of CD24, β-catenin, and proliferating cell nuclear antigen. Prognostic significance was assessed using Kaplan-Meier survival estimates and log-rank tests. Results: CD24 was overexpressed in the highly metastatic HCC cell line and in tumor tissues of patients with recurrent HCC. Depletion of CD24 caused a notable decrease in cell proliferation, migration, and invasiveness in vitro. Univariate and multivariate analyses revealed that CD24 was a significant predictor for overall survival and relapse-free survival. CD24 expression was correlated with poor prognosis independent of α-fetoprotein, tumor-node-metastasis stage, and Edmondson stage. High CD24 expression was significantly associated with cytoplasmic and nuclear accumulation of β-catenin (P = 0.023), high tumor proliferative status (P = 0.018), and diffused intrahepatic recurrence and distant metastasis (P = 0.026). Adjuvant transcatheter arterial chemoembolization after surgery reduced the rate of early recurrence (≤1 year) in CD24+ HCC patients (P = 0.024) but had no significant effect in CD24− patients (P = 0.284). Conclusions: Overexpression of CD24 in HCC was associated with high invasiveness and metastatic potential, high tumor proliferation status, and activation of the Wnt/β-catenin pathway. CD24 may be a novel predictor for poor prognosis of HCC patients after surgery. (Clin Cancer Res 2009;15(17):5518–27)

Small interfering RNA targeting the subunit ATP6L of proton pump V-ATPase overcomes chemoresistance of breast cancer cells

One of the mechanisms of multiple drug resistance (MDR) is inappropriate sequestration of basic chemotherapeutic agents in acidic endo-lysosomes of cells. The protonation, sequestration, and secretion (PSS) model indicates that drug distribution can be affected by intracellular pH such as lysosomal pH. The vacuolar-H(+)-ATPase (V-ATPase) plays an important role in regulation of intracellular pH by pumping protons into acidic endosomes via an ATP-driven process. In this study, ATP6L, the 16kDa subunit of V-ATPase, was knocked-down by anti-ATP6L small interfering RNA (siRNA) to study the effect on chemosensitivity in the human drug-resistant breast cancer cells MCF-7/ADR. Introduction of anti-ATP6L small interfering RNA duplex into drug-resistant cancer cells significantly inhibited the expression of ATP6L mRNA and protein, as detected by qRT-PCR and Western blot. Inhibition of ATP6L expression by siRNA in MCF-7/ADR sensitized the cells to the cytotoxicity of basic chemotherapeutic agents like doxorobicin, 5-fluorourocil and vincristine. This effect was mediated by a significant increase in lysosomal pH and retention of anticancer drugs into nuclei of cells. These results support the role of tumor acidity in resistance to chemotherapy and provide a rationale for the use of tumor pH modifier agents as coadjuvants in novel anticancer therapies.

High expression of Dickkopf-related protein 1 is related to lymphatic metastasis and indicates poor prognosis in intrahepatic cholangiocarcinoma patients after surgery

Dickkopf‐related protein 1 (DKK1) has been reported involved in metastasis and invasion in several tumors. This study sought to investigate the prognostic value of DKK1 in intrahepatic cholangiocarcinoma (ICC) and its role in promoting ICC metastasis.

Monoamine oxidase A suppresses hepatocellular carcinoma metastasis by inhibiting the adrenergic system and its transactivation of EGFR signaling

BACKGROUND & AIMS Monoamine oxidase A (MAOA), a catecholamine neurotransmitter degrading enzyme, is closely associated with neurological and psychiatric disorders. However, its role in cancer progression remains unknown. METHODS Hepatocellular carcinoma (HCC) tissue arrays (n=254) were used to investigate the correlation between MAOA expression and clinicopathological findings. In vitro invasion and anoikis assays, and in vivo intrahepatic and lung metastasis models were used to determine the role of MAOA in HCC metastasis. Quantitative real-time PCR, western blotting, immunohistochemical staining and HPLC analysis were performed to uncover the mechanism of MAOA in HCC. RESULTS We found that MAOA expression was significantly downregulated in 254 clinical HCC samples and was closely correlated with cancer vasoinvasion, metastasis, and poor prognoses. We then demonstrated that MAOA suppressed norepinephrine/epinephrine (NE/E)-induced HCC invasion and anoikis inhibition, and uncovered that the effects of NE/E on HCC behaviors were primarily mediated through alpha 1A (ADRA1A) and beta 2 adrenergic receptors (ADRB2). In addition to the canonical signaling pathway, which is mediated via adrenergic receptors (ADRs), we found that ADR-mediated EGFR transactivation was also involved in NE-induced HCC invasion and anoikis inhibition. Notably, we found that MAOA could synergize with EGFR inhibitors or ADR antagonists to abrogate NE-induced HCC behaviors. CONCLUSIONS Taken together, the results of our study may provide insights into the application of MAOA as a novel predictor of clinical outcomes and indicate that increasing MAOA expression or enzyme activity may be a new approach that can be used for HCC treatment.

CTHRC1 Acts as a Prognostic Factor and Promotes Invasiveness of Gastrointestinal Stromal Tumors by Activating Wnt/PCP-Rho Signaling

Gastrointestinal stromal tumors (GISTs) are the major gastrointestinal mesenchymal tumors with a variable malignancy ranging from a curable disorder to highly malignant sarcomas. Metastasis and recurrence are the main causes of death in GIST patients. To further explore the mechanism of metastasis and to more accurately estimate the recurrence risk of GISTs after surgery, the clinical significance and functional role of collagen triple helix repeat containing-1 (CTHRC1) in GIST were investigated. We found that CTHRC1 expression was gradually elevated as the risk grade of NIH classification increased, and was closely correlated with disease-free survival and overall survival in 412 GIST patients. In vitro experiments showed that recombinant CTHRC1 protein promoted the migration and invasion capacities of primary GIST cells. A luciferase reporter assay and pull down assay demonstrated that recombinant CTHRC1 protein activated noncanonical Wnt/PCP-Rho signaling but inhibited canonical Wnt signaling. The pro-motility effect of CTHRC1 on GIST cells was reversed by using a Wnt5a neutralizing antibody and inhibitors of Rac1 or ROCK. Taken together, these data indicate that CTHRC1 may serve as a new predictor of recurrence risk and prognosis in post-operative GIST patients and may play an important role in facilitating GIST progression. Furthermore, CTHRC1 promotes GIST cell migration and invasion by activating Wnt/PCP-Rho signaling, suggesting that the CTHRC1-Wnt/PCP-Rho axis may be a new therapeutic target for interventions against GIST invasion and metastasis.

SFRP4 was overexpressed in colorectal carcinoma

PurposeSecreted frizzled related proteins (SFRPs) play important roles in tumor progress through antagonizing Wnt signaling. However, SFRPs has not been systematically studied in colorectal tumors. The primary purpose of the study was to discuss the relationship between the expression of SFRPs and the clinicpathologic features of colorectal cancer (CRC).MethodsThe mRNA expressions of SFRPs were analyzed in 20 paired CRC and adjacent non-cancerous tissues by quantitative real-time RT-PCR. The protein expression of SFRP1 and SFRP4 were verified by Western blot in those 20 paired samples and were further detected by immunohistochemistry (IHC) in other 206 colorectal tissues.ResultsThe mRNA levels of SFRP1 and SFRP5 were significantly downregulated in 85 and 80% of CRC, respectively; but SFRP4 was overexpressed in 16 of 20 CRC samples. These findings were concordant with those obtained from the Western blotting in SFRP1 and SFRP4. Moreover, IHC analysis demonstrated increasing SFRP4 expression and decreasing SRFP1 levels in CRC compared with HIN and adenoma.ConclusionsSFRP1 and SFRP4 appear to be candidate markers for colorectal lesions. Unlike SFRP1 as a negative regulator for CRC carcinogenesis, SFRP4 may play quite different biological role in CRC.

Epigenetic inactivation of SLIT2 in human hepatocellular carcinomas.

Recent findings have shown that SLIT2 appears to function as a novel tumor suppressor gene. In addition, hypermethylation of its promoter region has been detected in various cancers, including breast and lung cancer, colorectal carcinoma, and gliomas. Here, we report for the first time that there is epigenetic silencing of SLIT2 in human hepatocellular carcinoma (HCC). Downregulation of SLIT2 was detected in 6 of 8 (75%) HCC cell lines by quantitative real-time RT-PCR (qRT-PCR), and the downregulation of SLIT2 was generally dependent on the degree of methylation at the promoter region. Furthermore, expression of SLIT2 was restored in relatively low-expressing cell lines after treatment with 5-aza-2-deoxycytidine (5-Aza-dC). Downregulation of SLIT2 expression was also detected in 45 of 54 primary HCC samples (83.3%), and the decrease in expression was significantly correlated with CpG island hypermethylation. This decrease of SLIT2 expression was also associated with lymph node metastasis in HCC. Moreover, overexpression of SLIT2 in SMMC-7721 cells induced by recombinant adenovirus suppressed cell growth, migration, and invasion, These results suggest that epigenetic inactivation of SLIT2 in HCC may be important in the development and progression of HCC. Thus, SLIT2 may be useful as a therapeutic target in the treatment of HCC.