Antitumor effect of forbesione isolated from Garcinia hanburyi on cholangiocarcinoma in vitro and in vivo

Abstract

Abstract. Cholangiocarcinoma (CCA) is a malignancy with no effective therapy and poor prognosis. Forbesione, a caged xanthone isolated from Garcinia hanburyi, has been reported to inhibit proliferation and to induce apoptosis in human CCA cell lines. The present study aimed to further explore the potential anticancer properties of forbesione by testing its effects against the hamster CCA cell line Ham-1 in vitro and in vivo. It was observed that forbesione inhibited the growth of Ham-1 cells in vitro and suppressed Ham-1 growth as allograft in hamsters by inducing cell cycle arrest at the S phase. This was mediated by decreasing the protein expression of cyclin E, cyclin A and cyclin-dependent kinase 2. In addition, increased expression of p21 and p27 was detected, which could possibly explain the reduced expression of proliferating cell nuclear antigen and of the bile duct cell marker cytokeratin 19 observed in forbesione-treated Ham-1 cells in vitro and in tumor tissues of forbesione-treated hamsters. Furthermore, forbesione induced apoptosis through multiple pathways. The death receptor pathway was activated by increased expression of Fas, Fas-associated death domain and activated caspase-3, along with decreased expression of procaspase-8 and procaspase-3. The mitochondrial pathway was driven by increased expression of B-cell lymphoma (Bcl)-2-like protein 4, activated caspase-9 and inhibitor of κB-α, along with decreased expression of Bcl-2, survivin, procaspase-9 and nuclear factor-κB/p65. The endoplasmic reticulum pathway was stimulated by increased expression of activated caspase-12 and decreased expression of procaspase-12. No side effects or toxicity were observed in forbesione-treated hamsters. Thus, forbesione is a potential drug candidate for cancer therapy that deserves further investigation. IntroductionCholangiocarcinoma (CCA), the malignant tumor of biliary epithelial cells, is the cancer of highest incidence in northeastern Thailand (1), and has increasing incidence and mortality worldwide (2,3). More than 70% of CCA patients have an advanced stage of the disease at the time of diagnosis, which makes curative surgical resection unfeasible (4). In these advanced CCA patients, chemotherapy is the usual treatment option (5). The systemic chemotherapy choices currently offered are 5-fluorouracil (5-FU), carboplatin plus 5-FU, gemcitabine and paclitaxel, which have failed to improve survival, and response rates are only ~20% (4). New therapeutic agents for CCA are urgently required.In the past few decades, natural bioactive substances derived from plants have been considered as important antitumor drug sources (6). Forbesione is a caged xanthone isolated from the resin and fruits of Garcinia hanburyi Hook. f. (family Guttiferae), which have been used in Thai traditional medicine (6,7). Gambogic acid, forbesione, isomorellin and isomorellinol, the caged xanthones isolated from G. hanburyi, are reported to exhibit antitumor activities (8) and cytotoxic effects in several cancer cell lines (8-10). Gambog...

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“…In addition, it was found that the expression of p27 and p21 was increased, which may describe why proliferating bile duct cell markers and cell nuclear antigen in forbesone-treated Ham-1 cells in vitro and in forbesone-treated hamster tumor tissues Cytokeratin 19 are reduced. In addition, forbesione promotes apoptosis through a variety of mechanisms [ 79 ]. Increased expression of Fas, Fas-related death domains, and activated caspase-3, as well as decreased expression of procaspase-3 and 8, activates the death receptor pathway [ 79 , 80 ].…”

“…In addition, forbesione promotes apoptosis through a variety of mechanisms [ 79 ]. Increased expression of Fas, Fas-related death domains, and activated caspase-3, as well as decreased expression of procaspase-3 and 8, activates the death receptor pathway [ 79 , 80 ]. Increased expression of activated caspase-9, B-cell lymphoma- (Bcl-) 2-like protein 4 and B-inhibitors, expression of Bcl-2, survivin, procaspase-9, and nuclear factor-B decreased p65, driving mitochondria way [ 80 ].…”

“…In forbesione-treated hamsters, no adverse effects or toxicity were identified. As a result, forbesione is observed as a promising cancer treatment candidate that warrants additional research [ 79 , 80 ].…”

Structural diversity and biological activities of caged Garcinia xanthones: recent updates

“…The biological activities and mechanisms of action of isomorellin (101) and forbesione (103) against cholangiocarcinoma has been a major research area for Reutrakul's research team since 2010 (Figure 8) [140][141][142][143][144]. Four caged xanthones, gambogic acid, 101, isomorellinol (102) and 103, have been tested against two cholangiocarcinoma cell lines, KKU-100 and KKU-M156 [140].…”

“…Forbesione has been demonstrated to inhibit the growth of the Ham-1 hamster cholangiocarcinoma cell line and Ham-1 allografts in a hamster model, with no observed in vivo toxicity or adverse effects [144]. This compound arrests the cell cycle at S phase through decreasing the protein expression of cyclin A, cyclin E and Cdk2, as well as promoting the upregulation of p21 and p27.…”