Effects of arsenic trioxide alone and in combination with bortezomib in multiple myeloma RPMI 8266 cells

Curcumin in treatment of hematological cancers: Promises and challenges

Hematological cancers include leukemia, myeloma and lymphoma and up to 178.000 new cases are diagnosed with these tumors each year. Different kinds of treatment including radiotherapy, chemotherapy, immunotherapy and stem cell transplantation have been employed in the therapy of hematological cancers. However, they are still causing death among patients. On the other hand, curcumin as an anti-cancer agent for the suppression of human cancers has been introduced. The treatment of hematological cancers using curcumin has been followed. Curcumin diminishes viability and survival rate of leukemia, myeloma and lymphoma cells. Curcumin stimulates apoptosis and G2/M arrest to impair progression of tumor. Curcumin decreases levels of matrix metalloproteinases in suppressing cancer metastasis. A number of downstream targets including VEGF, Akt and STAT3 undergo suppression by curcumin in suppressing progression of hematological cancers. Curcumin stimulates DNA damage and reduces resistance of cancer cells to irradiation. Furthermore, curcumin causes drug sensitivity of hematological tumors, especially myeloma. For targeted delivery of curcumin and improving its pharmacokinetic and anti-cancer features, nanostructures containing curcumin and other anti-cancer agents have been developed.

Bortezomib could down-regulate the expression of RANKL, inhibit cell proliferation and induce cell apoptosis in the human myeloma cell line RPMI 8226 by activating casepase-3

OBJECTIVE

In spite of bortezomib being developed and demonstrated as a safe drug therapy for multiple myeloma (MM), the role of bortezomib-induced receptor activator of nuclear factor (NF)-κB ligand (RANKL) in the MM cell lines remains to be understood. Thus the present study aims to explore the impact of bortezomib on RANKL expression, cell growth and apoptosis in human myeloma cell line RPMI 8226.

METHODS

Four experiment groups were set according to different concentrations of bortezomib, namely blank group (treated with DMEM solution free of other drugs), low-dose group (treated with 10 nmol/L bortezomib), middle-dose group (treated with 20 nmol/L bortezomib) and high-dose group (treated with 40 nmol/L bortezomib). Western blotting was adopted to detect RANKL protein expression. MTT assay was performed to detect cell proliferation. Flow cytometry was used to analyze cell cycle and apoptosis. Spectrophotometry was applied to determine caspases-3 activity.

RESULTS

Compared with the blank group, the RANKL protein expression, cell number at the S stage was reduced while cell inhibition rate, cell apoptosis rate and caspase-3 activity enhanced remarkably in the low-dose, middle-dose and high-dose groups with dose-dependent manner. Compared with those treated with bortezomib (20 nmol/L and 40 nmol/L) for 6 h, the RANKL expression was down-regulated, cell inhibition rate was increased, cells at the S stage were reduced, cell apoptosis rate was enhanced, and caspase-3 activity elevated in the RPMI 8226 cells as treated with bortezomib for 24 h, with a dose- and time-dependent manner.

CONCLUSIONS

Bortezomib could reduce the RANKL expression, inhibit cell proliferation and activate caspase-3 activity to induce cell apoptosis in RPMI 8266 cells.

Arsenic Trioxide Inhibits Cell Growth and Invasion via Down- Regulation of Skp2 in Pancreatic Cancer Cells

Arsenic trioxide (ATO) has been found to exert anti-cancer activity in various human malignancies. However, the molecular mechanisms by which ATO inhibits tumorigenesis are not fully elucidated. In the current study, we explored the molecular basis of ATO-mediated tumor growth inhibition in pancreatic cancer cells. We used multiple approaches such as MTT assay, wound healing assay, Transwell invasion assay, annexin V-FITC, cell cycle analysis, RT-PCR and Western blotting to achieve our goal. We found that ATO treatment effectively caused cell growth inhibition, suppressed clonogenic potential and induced G2-M cell cycle arrest and apoptosis in pancreatic cancer cells. Moreover, we observed a significant down-regulation of Skp2 after treatment with ATO. Furthermore, we revealed that ATO regulated Skp2 downstream genes such as FOXO1 and p53. These findings demonstrate that inhibition of Skp2 could be a novel strategy for the treatment of pancreatic cancer by ATO.