Sanguinarine inhibits Rac1b-rendered cell survival enhancement by promoting apoptosis and blocking proliferation

Abstract

Aim: Small GTPase Rac1 is a member of the Ras superfamily, which plays important roles in regulation of cytoskeleton reorganization, cell growth, proliferation, migration, etc. The aim of this study was to determine how a constitutively active Rac1b regulated cell proliferation and to investigate the effects of the Rac1b inhibitor sanguinarine. Methods: Three HEK293T cell lines stably overexpressing GFP, Rac1-GFP or Rac1b-GFP were constructed by lentiviral infection. The cells were treated with sanguinarine (1 μmol/L) or its analogue berberine (1 μmol/L) for 4 d. Cell proliferation was evaluated by counting cell numbers and with a BrdU incorporation assay. The levels of cleaved PARP-89 (an apoptosis marker) and cyclin-D1 (a proliferative index) were measured using Western blotting. Results: In 10% serum-containing media, overexpressing either Rac1 or Rac1b did not significantly change the cell proliferation. In the serum-starved media, however, the survival rate of Rac1b cells was significantly increased, whereas that of Rac1 cells was moderately increased. The level of cleaved PARP-89 was significantly increased in serum-starved Rac1 cells, but markedly reduced in serumstarved Rac1b cells. The level of cyclin-D1 was significantly increased in both serum-starved Rac1 and Rac1b cells. Treatment with sanguinarine, but not berberine, inhibited the proliferation of Rac1b cells, which was accompanied by significantly increased the level of PARP-89, and decreased both the level of cyclin-D1 and the percentage of BrdU positive cells. Conclusion: Rac1b enhances the cell proliferation under a growth-limiting condition via both anti-apoptotic and pro-proliferative mechanisms. Sanguinarine, as the specific inhibitor of Rac1b, is a potential therapeutic agent for malignant tumors with up-regulated Rac1b.

Rac1b enhances cell survival through activation of the JNK2/c-JUN/Cyclin-D1 and AKT2/MCL1 pathways

“…Rac1 protein was increased by 1.65(±0.16)-fold in LV-Rac1 cells as compared with LV-puro cells, similar to our previous report of a 2.0-fold change using a different lentiviral system [ 42 ]. Nascent Rac1b protein was only over-expressed in LV-Rac1b cells (Figure 1B ).…”

“…Rac1b promotes cell cycle progression and inhibits cell apoptosis, both of which are closely related to cell survival and tumorigenesis [ 33 , 34 , 40 - 42 ]. However, the underlying mechanisms of Rac1b in these processes are unclear.…”

Tumor cell expression of MMP3 as a prognostic factor for poor survival in pancreatic, pulmonary, and mammary carcinoma

“…EHT1864 is an inhibitor of Rac1 family GTPases which has been reported to have selectivity toward Rac1b [ 64 , 65 ] and which has been found to inhibit estrogen-dependent breast cancer cell proliferation in culture models [ 66 ]. Other possibilities include the natural products sanguinarine [ 67 ] and the anti-inflammatory drugs ketorolac [ 52 ] and ibuprofen [ 50 ], which also have been shown to inhibit Rac1b function, although the effects of these compounds as anticancer therapeutics in clinical settings remains to be evaluated.…”

Breaking a pathogen's iron will: Inhibiting siderophore production as an antimicrobial strategy

“…It may be important to determine if the sanguinarine is primarily interrupting an interaction of the fluorophore with the enzymes in each case, instead of inhibiting binding of the portion of the probe designed to mimic substrate. Additionally, sanguinarine has been shown to be thiol-reactive [88] and has been reported as an inhibitor of many diverse targets (some examples [89–98]).…”