Icaritin activates JNK-dependent mPTP necrosis pathway in colorectal cancer cells

Abstract

The colorectal cancer (CRC) is one leading contributor of cancer-related mortality worldwide. The search for effective anti-CRC agents is valuable. In the current study, we showed that icaritin (ICT), an active natural ingredient from the Chinese plant Epimedium, potently inhibited proliferation and survival of established (HT-29, HCT-116, DLD-1, and SW-620) and primary (patient-derived) CRC cells. Significantly, ICT mainly induced necrosis, but not apoptosis, in CRC cells. The necrosis inhibitor necrostatin-1 attenuated ICT-mediated cytotoxicity in CRC cells. We showed that ICT treatment in CRC cells induced mitochondrial permeability transition pore (mPTP) opening, which was evidenced by mitochondrial membrane potential (MMP) decrease and mitochondrial adenine nucleotide translocator-1 (ANT-1)-cyclophilin-D (CyPD) association. On the other hand, mPTP blockers, including sanglifehrin A, cyclosporin A, and bongkrekic acid, as well as siRNA-mediated knockdown of mPTP component (CyPD or ANT-1), significantly alleviated ICT-mediated cytotoxicity against CRC cells. We suggested that Jun-N-terminal kinase (JNK) activation by ICT mediated mPTP opening and subsequent CRC cell necrosis. JNK pharmacological inhibition, dominant negative mutation, or shRNA downregulation suppressed ICT-induced MMP reduction and subsequent HT-29 cell necrosis. In vivo, oral gavage of ICT dramatically inhibited HT-29 xenograft growth in nude mice. The in vivo activity by ICT was largely attenuated by co-administration with the mPTP blocker CsA. Collectively, our results showed that ICT exerts potent inhibitory effect against CRC cells in vitro and in vivo. JNK-dependent mPTP necrosis pathway could be key mechanism responsible for ICT's actions.

AMPK-autophagy inhibition sensitizes icaritin-induced anti-colorectal cancer cell activity

“…icaritin-induced HT-29 cell death, tested by the lactate dehydrogenase (LDH) release, was also significantly augmented with the autophagy inhibitors (Figure 2B). In line with our previous findings [10], treatment with icaritin (10 μM) alone failed to induce significant apoptosis activation in HT-29 cells (Figure 2C). Remarkably, when combined with the autophagy inhibitors, icaritin provoked dramatic apoptosis (Figure 2C), which was tested by the TUNEL staining assay (Figure 2C).…”

“…Hence, our group [10] and others [1, 8] have been focusing on exploring novel anti-CRC agents. Icaritin, the hydrolytic product of Icariin, is the main active ingredient of Epimedium , which is a known Traditional Chinese Medicine [11].…”

“…For instance, icaritin was shown to inhibit proliferation of prostate cancer cells [12], breast cancer cells [13], as well as hepatocellular carcinoma (HCC) cells [15] and endometrial cancer cells [16]. Our recent study has demonstrated that icaritin could also inhibit CRC cells in vitro and in vivo [10]. At the molecular level, we found that icaritin activated JNK-dependent mitochondrial permeability transition pore (mPTP) necrosis pathway to kill CRC cells [10].…”

“…Our recent study has demonstrated that icaritin could also inhibit CRC cells in vitro and in vivo [10]. At the molecular level, we found that icaritin activated JNK-dependent mitochondrial permeability transition pore (mPTP) necrosis pathway to kill CRC cells [10]. …”

Icaritin inhibits the expression of alpha-fetoprotein in hepatitis B virus-infected hepatoma cell lines through post-transcriptional regulation

“…Icaritin triggers the mitochondrial/caspase apoptotic pathway, by decreasing the Bcl-2/Bax protein ratio and increasing activation of caspase-3 in SMMC-7721 hepatoma cells [39]. Icaritin can also induce cell cycle arrest at the S phase, sustain the phosphorylation of ERK and p38 MAPK, and reduce c-Myc and MMP expressions to inhibit proliferation and promote apoptosis of various tumor cells [40, 41]. Furthermore, icaritin has little toxicity in normal hepatocytes compared with Cisplatin and has little effect on the growth and apoptosis of L02 human hepatocytes.…”