Hypoxia regulates Notch-3 mRNA and receptor activation in prostate cancer cells

Abstract

The Notch-3 receptor is a recognized key regulator of vascular responses and is increasingly associated with tumorigenesis. Hypoxia-inducible factors activate specific signaling pathways such as Notch in a number of cellular models. This study aimed to evaluate the regulation of Notch-3 by hypoxia in prostate cancer cells. Notch-3 gene and protein expression was established in a panel of aerobic and hypoxic prostate cell lines in vitro, the CWR22 xenograft model and RNA extracted from low grade (Gleason score < = 6); high grade (Gleason score > = 7); non-hypoxic (low HIF, low VEGF); hypoxic (high HIF, high VEGF) patient FFPE specimens. NOTCH-3 was upregulated in PC3 (3-fold), 22Rv1 (4.1-fold) and DU145 (3.8-fold) but downregulated in LnCaP (12-fold) compared to the normal cell lines. NOTCH-3 expression was modified following hypoxic exposure in these cells. NOTCH-3 was upregulated (2.2-fold) in higher grade and hypoxic tumors, when compared to benign and aerobic pools. In the CWR22 xenograft model, Notch-3 expression was restored in castrate resistant tumors. Nuclear translocation of the Notch-3 intracellular domain was no longer detected following exposure of cells to hypoxia but not associated with a change in expression of HES-1. Our data further identifies Notch-3 as a potentially key hypoxic-responsive member of the Notch pathway in prostate tumorigenesis.

Multiplex profiling identifies clinically relevant signalling proteins in an isogenic prostate cancer model of radioresistance

“…Notch inhibitors are increasingly explored as novel anti-cancer strategies 35–37 and their potential as radiosensitisers has been proposed 10 . We 38,39 , like others 40 , have previously reported the upregulation of the Notch-3 receptor in prostate cancer, and its role in hypoxic tumours 41 . Although Notch activity has been implicated in the radiation-induced stress response of prostate cancer cells 42 , no such strategy exists in prostate cancer.…”

The Role of Notch3 in Cancer

“…IL6 increases Notch3 through the microtubule associated protein kinase (MAPK) pathway that leads to mammosphere formation and increase of Carbonic anhydrase 9 (CA‐IX), an enzyme involved in survival during hypoxia . Notch3 is activated during hypoxia in prostate cancer cells, and Notch3‐Hypoxia‐inducible factor 1‐alpha (HIF‐1α) interaction is necessary for induction of CA‐IX in breast carcinoma cells . Notch3‐HIF‐1α interaction has also been found to be important in hypoxia‐related radiation resistance in lung cancer .…”

Taming the Notch Transcriptional Regulator for Cancer Therapy

“…Notch1 is the best-studied member of the family, and it is often overexpressed in human breast, colorectal, lung, pancreas, and prostate cancers [ 6 ]. Notch1 expression is induced by hypoxia, which is a common event in growing tumors [ 24 , 25 ]. Moreover, Notch signaling is activated downstream of a range of pathways deregulated in cancer, such as cMyc, p53, PI3K, or RAS [ 26 , 27 , 28 , 29 ].…”