Session Item

Monday
November 30
08:00 - 08:40
Physics Stream 2
4D imaging for radiation therapy using MRI and PET
3025
Teaching Lecture
Physics
17:09 - 17:17
Downregulation of BCL10 attenuates tumor growth and enhances radiosensitivity in pancreatic cancer
PH-0235

Abstract

Downregulation of BCL10 attenuates tumor growth and enhances radiosensitivity in pancreatic cancer
Authors: Wei|, Ming-Feng (1);Yang|, Shih-Hung(1);Yeh|, Kun-Huei (1);Lee|, Hsiao-Wei (1);Tien|, Yu-Wen (2);Cheng|, Ann-Lii(1);KUO|, Sung-Hsin(3)*[shkuo101@ntu.edu.tw];
(1)National Taiwan University Hospital, Department of Oncology, Taipei, Taiwan;(2)National Taiwan University Hospital, Department of Surgery, Taipei, Taiwan;(3)National Taiwan University Hospital, Division of Radiation Oncology- Department of Oncology, Taipei, Taiwan;
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Purpose or Objective

We previously reported that in breast cancer cell lines and diffuse large B-cell lymphoma cell lines, activation of TNF-α upregulates NF-κB signaling and nuclear translocation of BCL10. Because NF-κB activation has been shown to be involved in the pathogenesis and the radioresistance of pancreatic ductal adenocarcinoma (PDAC), we investigated whether inhibition of BCL10 can attenuate tumor growth and enhance radiosensitivity of PDAC cells.

Material and Methods

Three PDAC cell lines (mutant K-RAS lines: PANC-1 and AsPC-1; wild type K-RAS line: BxPC-3) were used in this study. We transfected three PDAC cell lines with BCL10 short hairpin RNA (shBCL10), and discovered that the majority of BCL10 translocated to cytoplasm from nuclei. Clonogenic assay was used to determine the radiosensitivity, whereas cell cycle was analyzed by flow cytometry. The expressions of BCL10-, cell cycle-, AKT/mTOR signaling pathway (p-mTOR, p-eIF4E, and p-rpS6), and NF-κB-related signaling molecules were assessed by immunoblotting. The DNA damage-related (γ-H2AX staining), and DNA double-strand break (DSB) repair-related (p-DNA-PKcs and p-ATM) molecules were also assessed. The differences of NF-κB activity between control cells and shBCL10 cells of PDAC were determined by NF-κB luciferase assay. The biological significances of BCL10 in determining tumor growth and radiotherapy effect of PDAC cell lines were further investigated in a PANC-1-xenograft model.

Results

We found that shBCL10 inhibited the cell viability and enhanced cytotoxicities of gemcitabine and oxaliplatin in three PDAC cell lines. Furthermore, shBCL10 differentially blocked cell cycle progression in PDAC cell lines; G1 phase arrest in wild-type K-RAS cell lines (downregulation of cyclin D1 expression in BxPC-3) and G2/M phase arrest in mutant K-RAS cell lines (downregulation of Cdc2 expression in PANC-1). ShBCL10 downregulated expressions of nuclear BCL10, BCL3, p-IκBα, and NF-κB (p65), and NF-κB activation. We observed that shBCL10 significantly inhibited cell viability and increased apoptosis (sub-G1 arrest) following 5 Gy irradiation in PANC-1 and BxPC-3 cells. When compared with normal PDAC cells treated with 5 Gy irradiation, the expression of AKT/mTOR signaling and DNA DSB repair-related molecules were downregulated, whereas cleaved caspase-3, cleaved PARP, and γ-H2AX expressions were upregulated in shBCL10-transfected PDAC cells treated with 5 Gy irradiation. Inhibition of BCL10 expression also reduced the tumor growth and enhanced radiosensitivity in a PANC-1-xenograft model. The expression of nuclear BCL10, BCL3, and NF-κB (p65) were also downregulated in the shBCL10-transfected PANC-1 xenograft tissues.

Conclusion

Our findings indicated that nuclear BCL10 plays an important role in controlling tumor growth and radiosensitivity of PDAC cells by activating AKT/mTOR, DNA-repair, and NF-κB-related signaling pathways.