CDK-associated Cullin 1 can promote cell proliferation and inhibit cisplatin-induced apoptosis in the AGS gastric cancer cell line

Abstract

BackgroundGastric cancer is a common and highly lethal malignancy in the world, but its pathogenesis remains elusive. In this study, we focus on the biological functions of CDK-associated Cullin1 (CAC1), a novel gene of the cullin family, in gastric cancer, which may help us to further understand the origin of this malignancy.MethodsThe AGS and MGC803 gastric cancer cell lines and the GES-1 gastric mucosa cell line were selected for study. At first, CAC1 expressions of those cell lines were examined by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) and western blot examinations, then CAC1 small interfering RNA (CAC1-siRNA) were designed and transfected into the AGS cell line with a relatively high level of CAC1. Once CAC1 was silenced, a series of biological characteristics of AGS cells such as cell proliferation, cell cycle, apoptosis, and expressions of apoptosis-related genes (P53, BCL2 and BAX) were determined by MTT, flow cytometry, qRT-PCR and western blot, respectively.ResultsCAC1 expression of AGS or MGC803 was much higher than that of GES-1. After CAC1 expression was effectively depressed by RNA interference in AGS cells, significant cell growth inhibition occurred. Furthermore, the proportion of cells treated with CAC1-siRNA increased in the G1 phase and decreased in the S phase, indicative of G1 cell cycle arrest. More importantly, the proportions of early/late apoptosis in AGS cells were enhanced with cis-diaminedichloroplatinum (cisplatin, CDDP) treatment, but to a higher extent with cisplatin plus CAC1-siRNA. Interestingly, BCL2 mRNA copies showed about a 30% decrease in the cisplatin group, but dropped by around 60% in the cisplatin plus CAC1-siRNA group. Conversely, the P53 mRNA expressions obtained nearly a two-fold increase in the cisplatin group, in addition to a five-fold increase in the cisplatin plus CAC1-siRNA group, and the BAX mRNA levels had almost a two- and four-fold augmentation, respectively. Meanwhile, P53, BAX and BCL2 showed the same alteration patterns in western blot examinations.ConclusionsCAC1 can promote cell proliferation in the AGS gastric cancer cell line. Moreover, it can prevent AGS cells from experiencing cisplatin-induced apoptosis via modulating expressions of P53, BCL2 and BAX.

CACUL1/CAC1 Regulates the Antioxidant Response by Stabilizing Nrf2

“…High oxidation levels, as well as defects that lead to high Nrf2 levels, are known characteristics of various cancer cell lines. Moreover, high CACUL1 levels in cancer cells have been reported in previous studies 33 34 35 . Our data concur with these observations, as high CACUL1 levels in cancers may lead to higher Nrf2 stabilization and activity in these cells, which can be expected to contribute to cellular tolerance against stress and cell death.…”

“…Our data concur with these observations, as high CACUL1 levels in cancers may lead to higher Nrf2 stabilization and activity in these cells, which can be expected to contribute to cellular tolerance against stress and cell death. Indeed, CACUL1 is reported to inhibit cisplatin induced apoptosis in gastric cancer cell lines 33 . Nrf2 stabilization may contribute to the cell cycle progression by CACUL1, as Nrf2 has been shown to be important for cell cycle progression in cancers 46 47 48 .…”

“…CACUL1/CAC1 is a presumptive Cullin domain containing protein whose function is yet to be characterized in depth. Several recent studies have shown that CACUL1 is highly expressed in various cancers, and promotes cell cycle progression in some cancer cell lines 33 34 35 . It has also been reported that CACUL1 is involved in ERα and RARα regulation by binding to and repressing their transcription activity in cells 36 37 .…”

Cullin Family Proteins and Tumorigenesis: Genetic Association and Molecular Mechanisms

“…CDK-associated CUL1 can promote cell proliferation and inhibit cisplatin-induced apoptosis in the AGS gastric cancer cell line via modulating the expression of p53 , BCL2 (B-cell lymphoma 2) and BAX (BCL2 associated X protein) 105 . CUL3-based poly-ubiquitination and p62-dependent aggregation of caspase-8 can mediate extrinsic apoptosis signaling 106 .…”

Expression and role of cyclophilin B in stomach cancer

“…Cell cycle-dependent protein kinases (CDKs) include CDK1, CDK4, cyclinD1, cycline, etc. ; these proteins regulate the cell cycle and may promote cell proliferation by regulating shortening of the cell cycle (Zheng et al, 2013).…”