The p44S10 locus, encoding a subunit of the proteasome regulatory particle, is amplified during progression of cutaneous malignant melanoma

Increased proteasome subunit protein expression and proteasome activity in colon cancer relate to an enhanced activation of nuclear factor E2-related factor 2 (Nrf2)

“…With respect to cancer, more and more evidence accumulates that, beside amplifications in signal-transduction pathways upstream to the UPP, the proteasome activity itself is also elevated in tumor cells (Ren et al, 2000;Wyke et al, 2004;Chen and Madura, 2005). This finding is in line with the fact that tumor cells are much more sensitive to proteasome inhibitors than normal cells (Adams, 2004), thus indicating that tumor cells particularly depend on high proteasome activity.…”

“…As a hallmark of this condition, the activity of the proteasome itself is increased in tumor cells, an event that may result from overexpression of certain protein components of the 26S-Pr (Ren et al, 2000;Chen and Madura, 2005;Rho et al, 2008). For the first time, this study shows a relation between an increased activation of Nrf2 in cancer and the overexpression of proteasomal subunit proteins-that is, S5a and a-5-along with an elevated proteasome activity.…”

“…For example, tumor samples from breast cancer patients show elevated expression level of certain proteasomal subunits when compared with normal tissue, along with higher proteasome activity (Chen and Madura, 2005). In melanoma, overexpression of the proteasomal subunit, S10, has been reported, emerging from gene amplification due to a chromosomal translocation (Ren et al, 2000) and accounting for an increased proteasome activity. In a recent study, the 20S-CP protein, PSMB7, was identified to be overexpressed in colon cancer tissue (Rho et al, 2008).…”

Differential cellular and molecular effects of bortezomib, a proteasome inhibitor, in human breast cancer cells

“…These in vivo studies are also supported by findings in tumor cell lines. For instance, MCF-7 human breast cancer cells express elevated levels of one of the highly conserved proteasome subunits (28). In the present study, basal proteasome activity was 1.5-to 2-fold higher in the bortezomib-resistant MCF-7 and BT-474 cells compared with the other cell lines assayed.…”

Regulation of PSMB5 Protein and β Subunits of Mammalian Proteasome by Constitutively Activated Signal Transducer and Activator of Transcription 3 (STAT3)

“…Neoplastic growth is frequently associated with increased proteasome activity and subunit expression to maintain protein homeostasis (15)(16)(17)(18)(19). Because of their stringent mode of activation, Nrf1 and Nrf2 are unlikely to promote the increased proteasome subunit expression in malignancies unless they are deregulated.…”