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Insulin-like growth factor binding protein-6 activates programmed cell death in non-small cell lung cancer cells
1Department of Thoracic/Head and Neck Medical Oncology, University of Texas-MD Anderson Cancer Center, Houston, Texas, TX 77030, USA.
Abstract:
Insulin-like growth factor binding proteins (IGFBPs) are secreted into the extra-cellular matrix and inhibit cell growth through IGF-dependent and -independent mechanisms. In this study, we investigated the role of IGFBP-6, a relatively unexplored member of the IGFBP family, in the proliferation of non-small cell lung cancer (NSCLC) cells. Infection of NSCLC cell lines in vitro with an adenovirus expressing human IGFBP-6 under the control of a CMV promoter (Ad5CMV-BP6) reduced NSCLC cell number through activation of programmed cell death, as shown by cell staining with Hoechst 33342 or DNA end-labeling with bromodeoxyuridine triphosphate. The growth regulatory effect of IGFBP-6 was investigated in vivo by intratumoral injection of Ad5CMV-BP6 in NSCLC xenografts established in nu/nu mice. A single injection of Ad5CMV-BP6 reduced the size of NSCLC xenografts by 45%. These findings indicate that IGFBP-6 is a potent inducer of programmed cell death in cancer cells and support investigations into IGFBP-6 as a potential target in cancer therapeutics.
Insights
Insulin-like growth factor binding protein 6 (IGFBP-6) effectively reduces non-small cell lung cancer (NSCLC) cell proliferation. This study shows IGFBP-6 induces programmed cell death, offering a potential new therapeutic target for NSCLC.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Insulin-like growth factor binding proteins (IGFBPs) regulate cell growth via IGF-dependent and -independent pathways.
- IGFBP-6 is an understudied member of the IGFBP family with potential roles in cancer.
Purpose of the Study:
- To investigate the role of IGFBP-6 in non-small cell lung cancer (NSCLC) cell proliferation.
- To evaluate IGFBP-6 as a potential therapeutic target for NSCLC.
Main Methods:
- In vitro studies involved infecting NSCLC cell lines with an adenovirus expressing human IGFBP-6 (Ad5CMV-BP6).
- Programmed cell death was assessed using Hoechst 33342 staining and DNA end-labeling.
- In vivo studies utilized NSCLC xenografts in nu/nu mice, with intratumoral injection of Ad5CMV-BP6.
Main Results:
- Ad5CMV-BP6 infection reduced NSCLC cell numbers by inducing programmed cell death.
- Intratumoral injection of Ad5CMV-BP6 led to a 45% reduction in NSCLC xenograft size after a single administration.
- IGFBP-6 demonstrated significant growth regulatory effects in both in vitro and in vivo models.
Conclusions:
- IGFBP-6 is a potent inducer of programmed cell death in cancer cells.
- These findings support the investigation of IGFBP-6 as a potential therapeutic target for NSCLC treatment.