Neutral endopeptidase (NEP) is differentially involved in biological activities and cell signaling of colon cancer cell lines derived from various stages of tumor development

Abstract

The presented studies were aimed at exploring the role of neutral endopeptidase (NEP) in the function of colon cancer cell lines LS 180 and SW 620, derived from different grades and stages of tumor development. NEP silencing by siRNA resulted in decreased viability and proliferation accompanied by increased apoptosis in both cell lines. Additionally, cell cycle arrest at the G2/M phase was observed, but only in LS 180 cells. Opposite to these results, serum-stimulated migration was increased in both cell lines. Furthermore, NEP silencing influenced the invasive activity of LS 180 and SW 620 cells in an opposite manner: while LS 180 cells showed an enhanced invasiveness, SW 620 cells exerted a reduced activity. An exploration of the activity of signaling molecules responsible for the function of tumor cells—Akt, PTEN, and FAK—after NEP silencing indicated that the endopeptidase is involved in their regulation. The increased phosphorylation level of Akt was accompanied by a decrease in PTEN in the presence of a high concentration of serum. A reduced concentration of serum did not change the phosphorylation status of Akt. Enhanced autophosphorylation of FAK was observed in LS 180 and SW 620 cells cultivated in a medium with a high concentration of serum. Taken together, these results confirm that NEP is implicated in the regulation of the survival, growth, and motile activity of colon cancer. This is also the first report which shows that NEP mediates cancer cell migration and invasiveness, but not growth and survival, through Akt/FAK signaling pathways.

CD10 inhibits cell motility but expression is associated with advanced stage disease in colorectal cancer

“…However, in SW480 CD10-, there was no significant difference in cell viability (Figure 2A). Our results can be compared to those obtained by Mizerska-Kowalska et al, who have also observed a reduced proliferation (determined by the BrdU method) and increased proportion of apoptotic cells following CD10 knockdown in the CRC cell line LS180 (Mizerska-Kowalska et al 2016).…”

“…In their case however, cell cycle analysis showed G2/M arrest upon transient CD10 knockdown in LS180 cells but not in SW620 (Mizerska-Kowalska et al 2016). In contrast, although we have observed the same net effect on proliferation following CD10 knockdown, we have obtained a small but significant decrease in G2/M.…”

“…In contrast, although we have observed the same net effect on proliferation following CD10 knockdown, we have obtained a small but significant decrease in G2/M. These small shifts in proliferation could be due to a reduction of focal adhesion kinase phosphorylation at Tyr 397, regulated by CD10 intrinsic signalling (Mizerska-Kowalska et al 2016). In terms of cell viability and proliferation, we must recognize the nature of the effects of the tumour microenvironment at the primary tumour (SW480) and metastatic site (SW620) and its long term implications in the metabolic activity of the cell lines hereby studied.…”

“…In SW620, they found that CD10 silencing caused increased migration but reduced invasion (Mizerska-Kowalska et al 2016). This also suggests that CD10 can inhibit cell migration and was attributed to the observation that CD10 silencing induced FAK phosphorylation thereby enhancing cell motility (Mizerska-Kowalska et al 2016). The reason for the differences in the results in SW620 between our study and that of Mizerska-Kowalska is uncertain but, taking all the data together, there is evidence to suggest that, CD10 can inhibit cell migration.…”

“…Comparable results were obtained by Mizerska-Kowalska et al who showed that CD10 silencing caused an increase in invasion and migration in LS180. In SW620, they found that CD10 silencing caused increased migration but reduced invasion (Mizerska-Kowalska et al 2016). This also suggests that CD10 can inhibit cell migration and was attributed to the observation that CD10 silencing induced FAK phosphorylation thereby enhancing cell motility (Mizerska-Kowalska et al 2016).…”