Pancreatic cancer cells are resistant to the growth‐inhibitory and apoptosis‐inducing effects of conventional chemotherapeutic agents. There are multiple genetic and epigenetic events during the process of carcinogenesis that enable the cancer cells to avoid normal growth constraints and apoptosis. Investigation of the mechanisms involved has led to multiple strategies that encourage cell death and apoptosis to occur. The pathways involved are summarized in this review, together with some recently developed strategies to promote cell death in this cancer and with a particular focus on the frondoside A, a novel triterpenoid glycoside isolated from the Atlantic sea cucumber, Cucumaria frondosa . Frondoside A inhibited proliferation of AsPC‐1 human pancreatic cancer cells in a concentration‐ and time‐dependent manner, as measured by 3 H‐thymidine incorporation and cell counting. In concert with inhibition of cell growth, frondoside A induced significant morphological changes consistent with apoptosis. Propidium iodide DNA staining showed an increase of sub‐G0/G1 cell population of apoptotic cells induced by frondoside A. Frondoside A–induced apoptosis was confirmed by annexin V binding and TUNEL assay. Furthermore, western blotting showed a decrease in expression of Bcl‐2 and Mcl‐1, an increase in Bax expression, activation of caspases 3, 7, and 9, and an increase in the expression of the cyclin‐dependent kinase inhibitor, p21. These findings show that frondoside A induced apoptosis in human pancreatic cancer cells through the mitochondrial pathway and activation of the caspase cascade. Finally, a very low concentration of frondoside A (10 μg/kg/day) inhibited growth of AsPC‐1 xenografts in athymic mice. In conclusion, new chemotherapeutic agents are desperately needed for pancreatic cancer because of the poor responsiveness to currently available treatment options. Frondoside A has potent growth inhibitory effects on human pancreatic cancer cells, and the inhibition of proliferation is accompanied by marked apoptosis. Frondoside A may be valuable for the treatment or chemoprevention of this devastating disease.

Patients with pancreatic cancer have little hope for cure because no effective therapies are available. Sansalvamide A is a cyclic depsipeptide produced by a marine fungus. We investigated the effect of a novel sansalvamide A analogue on growth, cell-cycle phases, and induction of apoptosis in human pancreatic cancer cells in vitro. The sansalvamide analogue caused marked time- and concentration-dependent inhibition of DNA synthesis and cell proliferation of two human pancreatic cancer cell lines (AsPC-1 and S2-013). The analogue induced G0/G1 phase cell-cycle arrest and morphological changes suggesting induction of apoptosis. Apoptosis was confirmed by annexin V binding. This novel sansalvamide analogue inhibits growth of pancreatic cancer cells through G0/G1 arrest and induces apoptosis. Sansalvamide analogues may be valuable for the treatment of pancreatic cancer.

Ujiki, Michael B. MD; Ding, Xian-Zhong PhD; Roginsky, Alexandra B. MD; Salabat, Mohammad Reza MD; Gu, Wenxin PhD; Silverman, Richard PhD; Talamonti, Mark S. MD; Bell, Richard H. MD; Adrian, Thomas E. PhD Author Information

Multiple chemotherapeutic agents have been used in pancreatic cancer without success. Sansalvamide A, the product of a marine fungus, has anti-cancer effects in several tumor cell lines, but has little effect in pancreatic cancer cells. We hypothesized that methylated and brominated, cyclic depsipeptide analogues of sansalvamide A would more potently inhibit human pancreatic cancer cell growth. Two human pancreatic cancer cell lines (AsPC-1 and S2-013) were treated with sansalvamide analogues (0.1-100 μM). Proliferation was measured by 3H-thymidine incorporation and cell counting at different time points (24-72 h). Cell cycle analysis was determined by flow cytometry with propidium iodide DNA staining. Cell cycle-associated proteins were investigated by western blotting. Apoptosis was confirmed by annexin-binding assay. Several sansalvamide analogues inhibited pancreatic cancer cell growth. The most potent analogue caused time- and concentration-dependent inhibition of DNA synthesis (46% decrease in AsPC-1 at 24 hours with 1 μM, P < 0.01) and cell proliferation (93% decrease in AsPC-1 at 72 hours with 10 μM, P < 0.01) with similar results in S2-013. This analogue induced G0/G1 phase cell cycle arrest similarly in both cell lines (S2-013 control 55.8% vs treated 75.9%, P < 0.002). The analogue reduced expression of cyclin E and cdk2, and induced expression of p21WAF1; all proteins that are involved in regulation of G0/G1 transition. The sansalvamide analogue increased the number of apoptotic cells in both cell lines (AsPC-1 control 5.6% vs analogue 20.6%, P = 0.03). Novel cyclic depsipeptide sansalvamide analogues inhibit growth of pancreatic cancer cells through suppression of cyclin E-associated cdk2 activity and G0/G1 arrest. Since they are structurally stable and exhibit potent anticancer effects, sansalvamide analogues may be valuable for the treatment of pancreatic cancer.

Pancreatic cancer is a disease carrying a dismal prognosis, with overall 5-year survival at around 4%. Recent clinical trials of adjuvant therapies have not found a dramatic increase in median survival. In the current review, we examine the available literature on flavonoids, a group of naturally occurring substances, for their effects on cancer cells and potential for therapy of pancreatic cancer in the future. With the available in vitro and in vivo data, it is likely that flavonoids will move into the clinical arena as therapeutic or preventive tools for cancer.

Pancreatic cancer has a dismal prognosis and current therapeutic and adjuvant protocols have not made a major impact on survival. New effective therapeutics or chemopreventive agents are desperately needed. We have previously shown that frondoside A, a triterpenoid glycoside from the sea cucumber inhibits pancreatic cancer cell growth and induces apoptosis. The present study was aimed at identifying the mechanisms by which frondoside A inhibits growth. The rapidly dividing S2-013 human pancreatic cancer cell line was used. Cells were placed in serum-free media for 24 hours prior to treatment with Frondoside A for 6 hours. RNA was extracted from three separate experiments using the TRIzol® reagent and purified using a Sigma kit. Oligonucleotide microarray analysis was performed and changes confirmed by real-time RT-PCR. Frondoside A induced marked changes in expression of multiple known genes as well as expressed sequence tags. Many of the downregulated genes were cell cycle-related. Four cell division cycle (cdc 20, 21, 45 & 47) genes as well as cyclin D3, cyclin A1, and cyclin-dependent kinase 5 were downregulated. Cyclooxygenase 1, which shows high expression in S2013 cells, was decreased. The upregulated genes included the cyclin-dependent kinase inhibitor p21waf1, death associated protein kinase 1 (DAPK-1), stanniocalcin, and several genes originally described in other pathologies including prostate differentiation factor and superoxide dismutase. In conclusion, Frondoside A is known to inhibit grown of pancreatic cancer cells in vitro and in vivo. The evidence presented here, provides clues as to the mechanism by which it alters the cell cycle. Frondoside A may be valuable for the treatment of pancreatic cancer.

Introduction: Pancreatic cancer poses a grave prognosis due to the advanced and inoperable stage at which it is usually diagnosed and lack of effective adjuvant therapy. We previously reported that a commercial product, Frondanol(r)-A5, produced from an edible sea cucumber inhibits growth of pancreatic cancer. In the present study, we examined its effects on cell cycle and apoptosis.