α-Hederin inhibits interleukin 6-induced epithelial-to-mesenchymal transition associated with disruption of JAK2/STAT3 signaling in colon cancer cells.

Colon cancer is the third most frequently diagnosed malignancy and has high morbidity worldwide. Epithelial-mesenchymal transition (EMT) has been increasingly implicated in colon cancer progression and metastasis. The present study was aimed to evaluate the potential antitumor activity of α-hederin, a monodesmosidic triterpenoid saponin isolated from Hedera helix, in human SW620 colon cancer cells stimulated with interleukin 6 (IL-6) for mimicking the tumor inflammatory microenvironment in vivo. Cell viability assay showed that IL-6 at 6.25 ng/ml significantly enhanced viability of SW620 cells, and thus this concentration was used to stimulate SW620 cells throughout this study. We observed that α-hederin concentration-dependently inhibited cell viability, migration and invasion in IL-6-treated SW620 cells. Moreover, α-hederin significantly restored IL-6-induced decrease in E-cadherin expression and abolished IL-6-induced increase in N-cadherin, vimentin, fibronectin, twist and snail at both mRNA and protein levels in SW620 cells. These data suggested that α-hederin suppressed IL-6-indcued EMT in colon cancer cells. Further molecular examinations showed that α-hederin inhibited phosphorylation of Janus Kinase 2 (JAK2) and Signal Transducer and Activator of Transcription 3(STAT3), and halted the nuclear translocation of phosphorylated STAT3 in IL-6-treated SW620 cells. In addition, JAK2/STAT3 signaling inhibitor AG490 not only produced similar inhibitory effects on EMT markers as α-hederin, but also synergistically enhanced α-hederin's inhibitory effects on EMT markers in IL-6-treated SW620 cells. Altogether, we demonstrated that α-hederin suppressed IL-6-induced EMT associated with disruption of JAK2/STAT3 signaling in colon cancer cells. Our data strongly suggested α-hederin as a promising candidate for intervention of colon cancer and metastasis.

The tolerability and pharmacology of interleukin-6 administered in combination with GM-CSF or G-CSF in the rhesus monkey.

The tolerability and potential target organ toxicity of rhIL-6 administered subcutaneously (s.c.) with rhGM-CSF or rhG-CSF were investigated in healthy nonhuman primates. Fifteen Rhesus monkeys were randomized to receive one of the following five regimens: rhIL-6, rhGM-CSF, rhG-CSF, rhIL-6 and rhGM-CSF, or rhIL-6 and rhG-CSF. Each cytokine was administered s.c. once daily at 20 micrograms/kg/day for 30-31 days. Marked increases in blood leukocyte counts (predominantly neutrophils) were observed in the rhGM-CSF and rhG-CSF treatment groups, but only a mild trend toward increased WBCs was observed with rhIL-6 alone. Platelet counts increased 1.7- to 2.2-fold in the rhIL-6 and rhGM-CSF groups. All regimens were well tolerated. RhIL-6, alone or in combination with either CSF, had no significant toxic effects at the dosages tested. Minimal to moderate bone marrow hyperplasia was observed in all except rhIL-6-treated animals, which correlated well with peripheral blood increases in WBCs. RhIL-6-treated animals demonstrated increased fibrinogen concentrations and erythrocyte sedimentation rates, decreased serum albumin/globulin ratios, and increased serum alpha-2-macroglobulin concentrations. Increased synthesis of acute-phase proteins was not observed in the other groups. Combining rhIL-6 with rhGM-CSF or rhG-CSF may reduce the rhIL-6-mediated acute-phase response while maintaining the desirable hematopoietic effects of the stimulating factors.

Manifestations of cancer cachexia induced by colon 26 adenocarcinoma are not fully ascribable to interleukin-6.

In order to further clarify the role of interleukin 6 (IL-6) in the pathogenesis of cachexia, recombinant human IL-6 (hIL-6) was administered s.c. by osmotic pump for 9 days at a dose of 1 or 10 micrograms/day into CDF1 mice inoculated with a non-cachexia-inducing subclone of colon 26 adenocarcinoma (clone 5), or with a cachexia-inducing subclone (clone 20) of this malignancy. The serum level of IL-6 in non-cachectic mice with clone-5 tumors was 35% lower than in cachectic mice bearing clone 20 of colon 26 adenocarcinoma on the 19th day after tumor inoculation. IL-6 administration induced anemia, thrombocytosis and visceral organ hypertrophy not only in mice with clone-5 tumors but also in control mice with no tumor burden. Lipolysis and proteolysis became conspicuous when a large dose (10 micrograms/day) of IL-6 was infused into mice with clone-5 tumors. However, IL-6 supplementation did not induce loss of body weight, a decline in food intake or lymphocytopenia, which were characteristically observed in cachectic mice with clone-20 tumors. In conclusion, IL-6 appears to be a permissive factor for the development of cachexia but, while it can induce some of the symptoms typical of cachexia, it cannot in itself induce the full cachectic syndrome.