PDEδ inhibition impedes the proliferation and survival of human colorectal cancer cell lines harboring oncogenic KRas

Abstract

Novelty and ImpactThe ‘undruggable’ KRas is a prevalent oncogene in CRC with poor prognosis. In hPDAC cells pharmacological targeting of PDEδ affects oncogenic KRas signaling, but it remained unclear whether this approach is transferable to other cancer cells. Here, we show that genetic and pharmacologic PDEδ inhibition also impedes the proliferation of oncogenic, but not wild-type KRas bearing CRC cells indicating that PDEδ inhibition is a specific tool for targeting growth of oncogenic KRas bearing CRC.AbstractRas proteins, most notably KRas, are prevalent oncogenes in human cancer. Plasma membrane localization and thereby signaling of KRas is regulated by the prenyl-binding protein PDEδ. Recently, we have reported the specific anti-proliferative effects of PDEδ inhibition in KRas-dependent human pancreatic ductal adenocarcinoma cell lines. Here, we investigated the proliferative dependence on the solubilizing activity of PDEδ of human colorectal cancer (CRC) cell lines with or without oncogenic KRas mutations. Our results show that genetic and pharmacologic interference with PDEδ specifically inhibits proliferation and survival of CRC cell lines harboring oncogenic KRas mutations whereas isogenic cell lines in which the KRas oncogene has been removed, or cell lines with oncogenic BRaf mutations or EGFR overexpression are not dependent on PDEδ. Pharmacological PDEδ inhibition is therefore a possible new avenue to target oncogenic KRas bearing CRC.

Small-Molecule Inhibition of the UNC-Src Interaction Impairs Dynamic Src Localization in Cells

“…To investigate whether disruption of the UNC119-Src interaction with inhibitor 3 and the resulting reduction in Src Y416 phosphorylation leads to an altered growth response, compound 3 was tested in a clonogenic assay ( Figure 5B). This assay monitors the survival and proliferation of the cells after compound treatment as reflected in the colony size and colony number, respectively (Klein et al, 2018). Since direct Src inhibition is known to lead to cell growth reduction in triple-negative MDA-MB-231 breast cancer cells because of Src dependency, this cell line was chosen for the clonogenic assay (Sá nchez-Bailó n et al , 2012).…”

The EGFR phosphatase RPTPγ is a redox‐regulated suppressor of promigratory signaling

“…To directly measure the effect of p22 phox -or RPTPγ-KO on cell proliferation, clonogenic assays under sustained EGF (20 ng/ml and 0.5% FCS; Figs 6E and EV5A) or in complete serum growth medium with 10% FCS at three linear increasing cell seeding densities (1, 2, and 3-fold) were performed (Fig EV5B). By renormalizing the area occupied by cell colonies after 7 days to the cell seeding density, a measure of average colony size and thereby proliferation of cells was obtained (Klein et al, 2019). As evident from the normalized area occupied by cell colonies and in agreement with proliferative signaling (Fig 6D), p22 phox -KO and RPTPγ-KO cells exhibited significant hyper-and hypo-proliferative behavior with respect to WT cells,respectively (Fig 6E).…”

RPTPγ is a redox-regulated suppressor of promigratory EGFR signaling

“…Whereas p22 phox -KO cells exhibited a hyperproliferative response to growth factors, RPTPγ-KO cells were clearly hypoproliferative, only increasing Rb phosphorylation at saturating EGF stimulus. These findings were independently assessed by clonogenic assays under growth factor serum conditions that provide a measurement of overall proliferation from the area occupied by cell colonies (Fig 5F) (Klein et al , 2019). These results are consistent with internalized liganded receptor complexes providing proliferative signals from endosomes whereas autocatalytically activated EGFR at the PM sustains promigratory signaling (Brüggemann et al , 2021).…”