Figure 1.
Colchicine and Selected Allocolchicines.
Figure 2.
Green 1 Selectively Reduces the Viability of Cancer cells.
(A) Pancreatic cancer cells (PANC-1) and normal human fibroblasts (NHFs) were treated with increasing concentrations of Green 1 and NSC 51046 and following treatment at the indicated time points, cells were incubated with WST-1 cell viability dye for 4 hours. Absorbance was read at 450 nm and results were expressed as a percent of the control. Values are expressed as mean ± SD from quadruplicates; (i) PANC-1 treated with NSC 51046 (Interaction between each concentration: ****p<0.0001; Control versus column factor: ****p<0.0001); (ii) NHF treated with NSC 51046 (Interaction between each concentration: ****p<0.0001; Control versus column factor: ****p<0.0001); (iii) PANC-1 treated with Green 1 (Interaction between each concentration: p = 0.9955; Control versus column factor: ****p<0.0001); (iv) NHF treated with Green 1 (Interaction between each concentration: p = 0.3642; Control versus column factor: *p = 0.0370) (B) Following treatment of human acute T cell leukemia cells (Jurkat) with Green 1, a trypan blue excluding assay was carried out. Cells were stained with trypan blue cell membrane impermeable dye and the numbers of trypan blue positive cells were obtained using a hemocytometer. Results are expressed as percent of trypan blue positive cells, indicating dead cells with non-intact cell membranes. Values are expressed as mean ± SD from two independent experiments.
Figure 3.
NSC 51046 Induces Non-Selective Apoptosis.
Following treatment with either Green 1(A) Pancreatic cancer cells (BxPC-3 and PANC-1) and normal human and fetal fibroblasts (NHFs and NFFs) were incubated with Hoechst 33342 dye to characterize nuclear morphology and detect the induction of apoptosis. Brightly stained, condensed nuclei accompanied by apoptotic bodies are indicative of apoptosis. (B) PANC-1 cells were incubated with Annexin V dye to verify apoptotic induction caused by NSC 51046. Cells were counterstained with Hoechst 33342 dye and propidium iodide (PI) to visualize nuclear morphology and cell death. Images shown are representative of two independent experiments at 48 hours following treatment with NSC 51046 and colchicine.
Figure 4.
Green 1 Induces Selective Pro-Death Autophagy.
(A) Pancreatic cancer cells, human leukemia cells (Jurkat) and NHFs were incubated with Monodansylcadaverine (MDC) to stain autophagic vacuoles and propidium iodide (PI) for cell death to determine if autophagic induction led to cell death. Bright, punctate staining is indicative of autophagy, as seen in our positive control (Tamoxifen treated cells). Images were taken at 400X magnification on a fluorescent microscope. (B) Western blot analyses of Beclin-1 expression and LC3 conversion were conducted on PANC-1 cells treated with 5.0 µM Green 1 at various time points. β-actin was measured as an internal control. Samples treated for 3 and 6 hours were compared to the early control, while the sample treated for 48 hours was compared to the 48-hour control. Results are expressed as mean ± SD from two independent experiments for both Western blots.
Figure 5.
Intracellular Targets of Colchicine Derivatives.
(A) Colchicine derivatives (Green 1 and NSC 51046) were incubated with porcine tubulin for an hour in a 96-well plate. The absorbance (OD 340 nm) was obtained every minute during the one hour incubation. Colchicine was used for comparison to the derivatives. (B) Isolated mitochondria from PANC-1 cells were treated with Green 1 and ROS production was measured using Amplex Red substrate in the presence of horseradish peroxidase (HRP). Results were compared to control untreated mitochondria, colchicine treated mitochondria and positive control, paraquat (PQ). Fluorescence readings were taken in 5 min intervals for 4 hours at Ex. 560 nm and Em.590 nm and expressed as relative fluorescence units (RFU). Results are a representative of three independent experiments.
Figure 6.
Green 1 is Well-Tolerated in Mice.
Following acclimatization, CD-1 nu/nu mice were separated into two groups, one group was injected subcutaneously in the right and left hind flanks with Me2SO in PBS (10 µL in 200 µL PBS), while the second group received subcutaneous injections of Green 1 (10 mg/kg/day for a total volume of 10 µL Green 1/200 µL PBS) three times a week for a period of one month. (A) Mice weights were recorded twice a week for the duration of the study. (B) Following the study, mice were sacrificed and their organs were obtained for histopathological assessment. Hematoxylin and Eosin staining was carried out on the tissue samples.
Figure 7.
DFT Structures of NSC 51046 and Green 1.