Melatonin Synergizes with Sorafenib to Suppress Pancreatic Cancer via Melatonin Receptor and PDGFR-ß/STAT3 Pathway.

BACKGROUND/AIMS: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignant tumors with poor prognosis. Conventional chemotherapies including gemcitabine have failed owing to weak response and side effects. Hence novel treatment regimens are urgently needed to improve the therapeutic efficacy. In this study, we aimed to assess the anticancer activity of melatonin and sorafenib as a novel therapy against PDAC. METHODS: We used various apoptosis assay and PDAC xenograft model to assess anticancer effect in vitro and in vivo. We applied phospho-receptor tyrosine kinase (RTK) array and phospho-tyrosine kinase array to explore the mechanism of the combined therapy. Western blotting, proximity ligation assay, and immunoprecipitation assay were also performed for validation. RESULTS: Melatonin synergized with sorafenib to suppress the growth of PDAC both in vitro and in vivo. The effect was due to increased apoptosis rate of PDAC cells that was accompanied by mitochondria dysfunction. The enhanced anticancer efficacy by the co-treatment could be explained by blockade of PDGFR-ß/STAT3 signaling pathway and melatonin receptor (MT)-mediated STAT3. CONCLUSIONS: Melatonin reinforces the anticancer activity of sorafenib by downregulation of PDGFR-ß/STAT3 signaling pathway and melatonin receptor (MT)-mediated STAT3. The combination of the two agents might be a potential therapeutic strategy for treating PDAC.

An ethyl acetate fraction of Artemisia capillaris (ACE-63) induced apoptosis and anti-angiogenesis via inhibition of PI3K/AKT signaling in hepatocellular carcinoma.

In cancer treatment, herbal medicines may be a good choice because of the reduced risk of adverse side effects. Artemisia capillaris has been recognized as a promising candidate due to its hepatoprotective effects. Herein, we investigated whether A. capillaris-derived fraction (ACE-63) could inhibit the progression of hepatocellular carcinoma (HCC) and its underlying mechanism. In this study, ACE-63 effectively inhibited the growth and proliferation of HCC cells. ACE-63 induced apoptosis, as observed using Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, which was accompanied with increases in cleaved Poly (ADP-ribose) polymerase (PARP) and caspase-3 in HCC cells. Additionally, the pro-apoptotic effect of ACE-63 was demonstrated by a decrease in the expression of the X-linked inhibitor of apoptosis protein (XIAP) and survivin via a loss of mitochondrial membrane potential. In an ex vivo model, ACE-63 significantly inhibited tumor cell growth and induced apoptosis by increasing the expression of cleaved caspase-3 and DNA fragmentation. In addition, ACE-63 decreased the expression of hypoxia-inducible factor-1α and vascular endothelial growth factor and inhibited tube formation of human umbilical vein endothelial cells. A mechanistic study revealed that ACE-63 effectively suppressed the PI3K/AKT/mTOR signaling pathways, which were observed as a target signaling by phosphokinase array. Taken together, our findings demonstrate that ACE-63 could not only efficiently induce apoptosis but also inhibit the growth/angiogenesis of human HCC cells by blocking the PI3K/AKT/mTOR signaling pathway, suggesting that ACE-63 may be a new chemotherapeutic candidate against HCC.

ONC201 induces the unfolded protein response (UPR) in high- and low-grade ovarian carcinoma cell lines and leads to cell death regardless of platinum sensitivity.

OBJECTIVES: Treatment of both platinum resistant high grade (HG) and low-grade (LG) ovarian cancer (OVCA) poses significant challenges as neither respond well to conventional chemotherapy leading to morbidity and mortality. Identification of novel agents that can overcome chemoresistance is therefore critical. Previously, we have demonstrated that OVCA has basal upregulated unfolded protein response (UPR) and that targeting cellular processes leading to further and persistent upregulation of UPR leads to cell death. ONC201 is an orally bioavailable Dopamine Receptor D2 inhibitor demonstrating anticancer activity and was found to induce UPR. Given its unique properties, we hypothesized that ONC201 would overcome platinum resistance in OVCA. METHODS: Cisplatin sensitive and resistant HG OVCA and two primary LG OVCA cell lines were studied. Cell viability was determined using MTT assay. Cell migration was studied using wound healing assay. Apoptosis and mitochondrial membrane potential were investigated using flow cytometry. Analysis of pathway inhibition was performed by Western Blot. mRNA expression of UPR related genes were measured by qPCR. In vivo studies were completed utilizing axillary xenograft models. Co-testing with conventional chemotherapy was performed to study synergy. RESULTS: ONC201 significantly inhibited cell viability and migration in a dose dependent manner with IC50's from 1-20 µM for both cisplatin sensitive and resistant HG and LG-OVCA cell lines. ONC201 lead to upregulation of the pro-apoptotic arm of the UPR, specifically ATF-4/CHOP/ATF3 and increased the intrinsic apoptosispathway. The compensatory, pro-survival PI3K/AKT/mTOR pathway was downregulated. In vivo, weekly dosing of single agent ONC201 decreased xenograft tumor size by ~50% compared to vehicle. ONC201 also demonstrated significant synergy with paclitaxel in a highly platinum resistant OVCA cell-line (OV433). CONCLUSIONS: Our findings demonstrate that ONC201 can effectively overcome chemoresistance in OVCA cells by blocking pro-survival pathways and inducing the apoptotic arm of the UPR. This is a promising, orallybioavailable therapeutic agent to consider in clinical trials for patients with both HG and LG OVCA.

Artemisia capillaris extract AC68 induces apoptosis of hepatocellular carcinoma by blocking the PI3K/AKT pathway.

Artemisia capillaris Thunberg (AC) has been widely used to treat various diseases including hepatitis and is known to affect many cellular events such as cell proliferation and apoptosis. Herein a potent ethyl acetate fraction (AC68) was newly extracted from AC, and was assessed for its anti-cancer efficacy in progression and growth of hepatocellular carcinoma (HCC). AC68 dose-dependently inhibited the growth and proliferation of two HCC cell lines. The AC68-induced apoptosis was observed by increased levels of cleaved caspase-3 and decreased survivin, XIAP, and MCL-1 expression via mitochondria membrane potential change, as well as elevated numbers of TUNEL-positive apoptotic cells. AC68 was also found to suppress invasion and migration of HCC cells. Moreover, it inhibited PI3K/AKT signaling pathway in vitro and in vivo. In vivo study showed that AC68 significantly inhibited tumor growth in HCC mouse xenograft model, and induced apoptosis by increasing the expression of cleaved caspase-3. The expression of PCNA was decreased by the treatment of AC68. Taken together, our data demonstrated that AC68 not only induced apoptosis but also inhibited cell growth, migration, and invasion of liver cancer cells by blocking the PI3K/AKT pathway. We suggest that AC68 may be a potent chemotherapeutic candidate for the treatment of HCC.

HS-173, a novel PI3K inhibitor suppresses EMT and metastasis in pancreatic cancer.

Pancreatic cancer is one of the most aggressive solid malignancies prone to metastasis. Epithelial-mesenchymal transition (EMT) contributes to cancer invasiveness and drug resistance. In this study, we investigated whether HS-173, a novel PI3K inhibitor blocked the process of EMT in pancreatic cancer. HS-173 inhibited the growth of pancreatic cancer cells in a dose- and time-dependent manner. Moreover, it significantly suppressed the TGF-ß-induced migration and invasion, as well as reversed TGF-ß-induced mesenchymal cell morphology. Also, HS-173 reduced EMT by increasing epithelial markers and decreasing the mesenchymal markers by blocking the PI3K/AKT/mTOR and Smad2/3 signaling pathways in pancreatic cancer cells. In addition, HS-173 clearly suppressed tumor growth without drug toxicity in both xenograft and orthotopic mouse models. Furthermore, to explore the anti-metastatic effect of HS-173, we established pancreatic cancer metastatic mouse models and found that it significantly inhibited metastatic dissemination of the primary tumor to liver and lung. Taken together, our findings demonstrate that HS-173 can efficiently suppress EMT and metastasis by inhibiting PI3K/AKT/mTOR and Smad2/3 signaling pathways, suggesting it can be a potential candidate for the treatment of advanced stage pancreatic cancer.

CD-200 induces apoptosis and inhibits Bcr-Abl signaling in imatinib-resistant chronic myeloid leukemia with T315I mutation.

Chronic myeloid leukemia (CML) is characterized by a constitutively active Bcr-Abl tyrosine kinase. Although Imatinib has been proven to be an effective drug against CML, its resistance has been observed with disease relapse due to T315I predominant point mutation. Liriodendron tulipifera L., one of the fastest growing hardwood tree species, exerts antioxidant activity and anti-inflammatory effects. However, its anticancer effect has been minimally reported. In this study, we extracted CD-200 from Liriodendron tulipifera L. and investigated its effect on cell survival or apoptosis in CML cells with Bcr-Abl/T315I (BaF3/T315I) as well as wild-type Bcr-Abl (BaF3/WT). CD-200 inhibited cell proliferation in the BaF3/WT cells, and also in the BaF3/T315I cells with Imatinib resistance. Moreover, it strongly inhibited Bcr-Abl signaling pathways in a dose-dependent manner. Also, it significantly increased the sub-G1 phase and the expression of cleaved PARP and caspase-3, as well as the TUNEL-positive apoptotic cells. In addition, we observed that CD-200 induced apoptosis with a loss of mitochondrial membrane potential by decreasing the expression of Mcl-1 and survivin. Furthermore, CD-200 showed a significant inhibition in tumor growth, compared to Imatinib in BaF3/T315I mouse xenograft models. Taken together, our study demonstrates that CD-200 exhibits apoptosis induction and anti-proliferative effect by blocking the Bcr-Abl signaling pathways in the Bcr-Abl/T315I with resistance to Imatinib. We suggest that CD-200 may be a natural product to target Bcr-Abl and overcome Imatinib resistance in CML patients.