Norcantharidin induces anoikis through Jun-N-terminal kinase activation in CT26 colorectal cancer cells

Abstract

Norcantharidin (NCTD), a chemically modified form of cantharidin, is a potential anticancer drug. This study investigated the effect of NCTD on anoikis in CT26 colorectal adenocarcinoma cells. NCTD treatment of CT26 cells showed a dose-dependent and time-dependent decrease in viability and cell proliferation. Growth inhibition was accompanied by cell cycle arrest in the S and G2/M phases. Mitogen-activated protein kinase expression, assayed by Western blot, was unchanged except for Jun-N-terminal kinase (JNK). At 24 h of treatment with 0-20 micromol/l NCTD, JNK expression increased at 24 h, but then decreased at 48 h; in contrast, the phosphorylated JNK levels markedly increased. JNK inhibitor (SP600125) in the culture effectively blocked NCTD-induced cytotoxicity and detachment of cells. CT26 cells treated with NCTD not only displayed inhibited cell adhesion and down-expression of integrin beta1, but also changed from being shuttle-shaped to round, the latter cells being more susceptible to anoikis-mediated apoptosis. Flow cytometric assay of the DNA content in NCTD-treated CT26 cells at 24 and 48 h showed a marked increase in the sub-G1 level, indicating that NCTD induced apoptosis. NCTD inhibited the viability of CT26 cancer cells preferentially over normal bone marrow and mononuclear cells. NCTD inhibits CT26 cancer cells by blocking proliferation and inducing anoikis-mediated apoptosis, a process that might be regulated by JNK activation.

Norcantharidin reduced cyclins and cytokines production in human peripheral blood mononuclear cells

“…NCTD has been demonstrated with various biological activities including: (1) It is mainly used for the treatment of hepatoma and upper gastrointestinal carcinomas in China (Liu et al, 2008); (2) NCTD blocks colon cancer cells growth by regulation of JNK activation (Chen et al, 2008); (3) The anti-tumor activity of NCTD depends on induction of apoptosis and cleavage of Cdc6 proteins (Li et al, 2006); (4) It can inhibit leukemia cells proliferation through induction of TNF-α production ; (5) NCTD effectively reduces the proteinuria and prevents kidney inflammation and fibrosis in mice (Liu et al, 2008); and (6) It is a protein phosphatase 1 and 2A inhibitor (Hart et al, 2004). This is the first immunomodulatory action on PBMC described for NCTD.…”

Norcantharidin is a small-molecule synthetic compound with anti-angiogenesis effect

“…The drug blocked proliferation and induced anoikis-mediated apoptosis through modulation of JNK/ mitogen-activated protein kinase (MAPK) activation (Chen et al 2008). However, the anti-angiogenic effect of NCTD and its molecular mechanism of action remain unknown.…”

“…NCTD is currently used as an anti-cancer drug in China. NCTD inhibits proliferation of various kinds of cancer cells, including hepatoma, leukemia, and colorectal carcinoma by cell cycle arrest and apoptosis induction (Liao et al 2007;Hill et al 2007); in addition, this drug has acceptable toxicity to normal cells (Chen et al 2008).…”

Curcumin sensitizes non-small cell lung cancer cell anoikis through reactive oxygen species-mediated Bcl-2 downregulation

“…Resistance to anoikis is associated with a high degree of tumor metastasis and advanced stage of cancers [9][10][11][12]. Several signaling pathways including c-Jun amino-terminal kinase (JNK) [13], phosphatidylinositol-3 kinase (PI3 K)/Akt [14], focal adhesion kinase (FAK) [15], and extracellular signalregulated protein kinase (ERK) [16,17] have been implicated in anoikis regulation. Moreover, increasing evidence suggest the importance of apoptosis-regulatory proteins in the Bcl-2 family in cell survival after detachment [18].…”