Friday, October 17th, 2008.

Cancer Research. 2008 Oct 15;68(20):8333-41. [Link]

Kashiwakura Y, Ochiai K, Watanabe M, Abarzua F, Sakaguchi M, Takaoka M, Tanimoto R, Nasu Y, Huh NH, Kumon H.

Innovation Center Okayama for Nanobio-Targeted Therapy, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan. yu-kashi@cj9.so-net.ne.jp

Abstract

REIC/Dickkopf-3 (Dkk-3), a tumor suppressor gene, has been investigated in gene therapy studies. Our previous study suggested that REIC/Dkk-3-induced apoptosis mainly resulted from phosphorylation of c-Jun-NH₂ kinase (JNK) in prostate cancer cells. However, the precise mechanisms, especially the molecular mechanisms regulating JNK phosphorylation, remain unclear. In this study, we investigated the mechanisms participating in JNK phosphorylation in the context of a refractory cancer disease, malignant mesothelioma (MM). Adenovirus-mediated overexpression of REIC/Dkk-3 induced apoptosis mainly through JNK activation in immortalized MM cells (211H cells). Interestingly, transcriptional down-regulation of inhibition of differentiation-1 (Id-1) was detected in REIC/Dkk-3-overexpressed 211H cells. Moreover, restoration of Id-1 expression antagonized REIC/Dkk-3-induced JNK phosphorylation and apoptosis. Mutagenesis experiments with the 2.1-kb human Id-1 promoter revealed that activating transcription factor 3 (ATF3) and Smad interaction, with their respective binding motifs, was essential for REIC/Dkk-3-mediated suppression of Id-1 promoter activity. ATF3 activation was probably induced by endoplasmic reticulum stress. Finally, we showed strong antitumor effects from REIC/Dkk-3 gene transfer into the pleural cavity in an orthotopic MM mouse model. Relative to control tumor tissue, REIC/Dkk-3-treated tumor tissue showed down-regulated expression of Id-1 mRNA, enhanced expression of phosphorylated JNK, and an increased number of apoptotic cells. In summary, we first showed that both ATF3 and Smad were crucially and synergistically involved in down-regulation of Id-1, which regulated JNK phosphorylation in REIC/Dkk-3-induced apoptosis. Thus, gene therapy with REIC/Dkk-3 may be a promising therapeutic tool for MM.

Keywords: REIC/Dkk-3, malignant mesothelioma, gene therapy

Glossary

therapy

any of the measures taken to treat a disease. Unproven therapy is any therapy that has not been scientifically tested and approved. Use of an unproven therapy instead of standard (proven) therapy is called alternative therapy. Some alternative therapies have dangerous or even life-threatening side effects. For others, the main danger is that a patient may lose the opportunity to benefit from standard therapy. Complementary therapy, on the other hand, refers to therapies used in addition to standard therapy. Some complementary therapies may help relieve certain symptoms of cancer, relieve side effects of standard cancer therapy, or improve a patient's sense of well-being. The ACS recommends that patients considering use of any alternative or complementary therapy discuss this with their health care team.

prostate

(pros-tate)  a gland found only in men. It is just below the bladder and in front of the rectum. The prostate makes a fluid that is part of semen. The tube that carries urine, the urethra, runs through the prostate.

gene therapy

a new type of treatment in which defective genes are replaced with normal ones. The new genes are delivered into the cells by viruses or proteins. (Mesothelioma gene therapy treatment options.)

gene

a segment of DNA that contains information on hereditary characteristics such as hair color, eye color, and height, as well as susceptibility to certain diseases. Women who have BRCA1 or BRCA2 gene mutations (defects) have an inherited tendency to develop breast cancer.

differentiation

(dif-er-en-she-A-shun) the normal process through which cells mature so they can carry out the jobs they were meant to do. Cancer cells are poorly differentiated.

cancer

malignancy; a group of diseases typified by abnormal, generally out-of-control, cell growth.

tissue

a collection of cells, united to perform a particular function.

tumor

an abnormal lump or mass of tissue. Tumors can be benign (not cancerous) or malignant (cancerous).

mesothelioma

a tumor derived from mesothelial tissue, such as the peritoneum (lining the abdomen) or pleura (lining the lungs). More on mesothelioma.

apoptosis

a type of cell death in which the cell basically commits suicide; scientists believe some types of cancer may originate from an interruption of this programmed cell death, allowing cells to grow out of control.

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