Table 3: Consequences of inhibiting IGFBP activity and cancer.

IGFBPsExpressionResults of inhibiting IGFBP activityReference

IGFBP-1LiverIt can induce or inhibit the IGF actions in many types of cells. As an example of the inhibiting activity of IGFBP-1, it inhibited IGF-I-induced growth in MCF-7 breast cancer cells.[30, 157]

IGFBP-2Liver, adipocytes, reproductive system, and central nervous system IGFBP-2 level changes were associated with the development of different types of cancer including breast and prostate cancer. In prostate cancer, high level of serum IGFBP-2 was associated with low grade prostate cancer.[189, 190]

IGFBP-3Circulating carrier protein, expressed in many tissuesIGFBP-3 plays important role in different types of human cancers. IGFBP-3 can induce apoptosis by increasing the ratio of proapoptotic to antiapoptotic proteins in breast cancer cells.[191]

IGFBP-4Liver, bone tissue, and musclesIGFBP-4 showed a strong inhibitory effect on IGF-1 by preventing the activation of the IGF-1R, when the IGFBP-4 is found in the tissue. Conversely, intravenous administration of IGFBP-4, in the presence of a protease, will promote cellular proliferation.[79, 192195]

IGFBP-5Mammary glandsIn breast cancer, IGFBP-5 induced apoptosis and inhibited cellular differentiation in an IGF-dependent manner.[196, 197]

IGFBP-6Epithelial layer of human bronchial organIt can inhibit IGF-2 activity mediated through the IGF-1R, including proliferation, differentiation, migration, and survival in different cell lines.[198, 199]