5-Fluorouracil signaling through a calcium–calmodulin-dependent pathway is required for p53 activation and apoptosis in colon carcinoma cells

Abstract

5-Fluorouracil (5-FU) is an anti-metabolite that is in clinical use for treatment of several cancers. In cells, it is converted into three distinct fluoro-based nucleotide analogs, which interfere with DNA synthesis and repair, leading to genome impairment and, eventually, apoptotic cell death. Current knowledge states that in certain cell types, 5-FU-induced stress is signaling through a p53-dependent induction of tumor necrosis factor-receptor oligomerization required for death-inducing signaling complex formation and caspase-8 activation. Here we establish a role of calcium (Ca 2 þ ) as a messenger for p53 activation in response to 5-FU. Using a combination of pharmacological and genetic approaches, we show that treatment of colon carcinoma cells stimulates entry of extracellular Ca 2 þ through long lasting-type plasma membrane channels, which further directs posttranslational phosphorylation of at least three p53 serine residues (S15, S33 and S37) by means of calmodulin (CaM) activity. Obstructing this pathway by the Ca 2 þ -chelator BAPTA (1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid) or by inhibitors of CaM efficiently reduces 5-FUinduced caspase activities and subsequent cell death. Moreover, ectopic expression of p53 S15A in HCT116 p53 À / À cells confirmed the importance of a Ca 2 þ -CaM-p53 axis in 5-FU-induced extrinsic apoptosis. The fact that a widely used therapeutic drug, such as 5-FU, is operating via this pathway could provide new therapeutic intervention points, or specify new combinatorial treatment regimes.

Activation of the p53 Transcriptional Program Sensitizes Cancer Cells to Cdk7 Inhibitors

“…In HCT116 cells exposed to high-dose 5-FU, DR5 and FAS were previously shown to translocate to the plasma membrane, and DR5 silencing impeded caspase activation (Can et al, 2013). To assess the involvement of DR5, FAS and DR4 (another death receptor) in synthetic lethality, we silenced expression of each with small interfering RNA (siRNA), treated cells with 3-MB-PP1 and either 5-FU or nutlin-3, and measured markers of apoptosis.…”

Calcium homeostasis in cisplatin resistant epithelial ovarian cancer

“…Various studies have described changes in different cancer cell types and models in intracellular Ca 2+ signals induced by some anti-cancer agents. Drug treatments that appeared to increase Ca 2+ influx as a result of short-term (0 to 8 h) exposure included 5-Fluorouracil (5FU) (Can et al 2013), dexamethasone (Abdul-Azize et al 2017), Tipifarnib (Cuevas 2011;Yanamandra et al 2011) or ionizing radiation (Klumpp et al 2016). Drugs such as arsenic trioxide (As 2 O 3 ) (Gunes et al 2009) and gamitrinib (Park et al 2014) were suggested to promote ER Ca 2+ release during short-term exposure.…”

Toll-like receptor-5 agonist Entolimod broadens the therapeutic window of 5-fluorouracil by reducing its toxicity to normal tissues in mice

“…High-dose continuous treatment with 5-FU causes DNA damage in proliferating cells through inhibition of thymidylate synthase, a key component of DNA synthesis and repair pathways. In addition to tumors, HP and GI cells demonstrate 5-FU sensitivity [22, 23]. Hematological toxicity of 5-FU involves p53-mediated induction of ribosomal stress, which blocks translation [24, 25].…”