E-cadherin increasing multidrug resistance protein 1 via hypoxia-inducible factor-1α contributes to multicellular resistance in colorectal cancer

When cancer cells have been cultured as three-dimensional (3D) cultures or in vivo, they decrease sensitivity to anticancer drugs. This is called multicellular resistance, and the mechanism is not fully understood. Here, we report that E-cadherin increasing multidrug resistance protein 1 (MDR1) via hypoxia-inducible factor-1α (HIF-1α) contributes to multicellular resistance in colorectal cancer. The MDR1 protein level was higher in 3D cultures than in monolayer cells. When dispersed cells from 3D cultures were grown as monolayer cells again, the MDR1 protein level decreased to the similar level of cells maintained as monolayer all through. Knockdown of MDR1 significantly decreased multicellular resistance. Knockdown of E-cadherin decreased MDR1 in 3D cultures but did not detectably change MDR1 in monolayer cells. E-cadherin was expressed uniformly in 3D cultures while the MDR1 protein level was higher in the center of 3D cultures than in the peripheral part. Knockdown of E-cadherin decreased E-cadherin uniformly in 3D cultures but mainly decreased MDR1 at the center of 3D cultures. These suggest that knockdown of E-cadherin decreasing MDR1 may be by an indirect mechanism. HIF-1α was remarkably increased in 3D cultures. Knockdown of E-cadherin decreased intercellular junctions, increased intercellular space, and decreased HIF-1α in 3D cultures. Knockdown of HIF-1α decreased MDR1 in 3D cultures. Knockdown of E-cadherin increased β-catenin uniformly in 3D cultures, and knockdown of β-catenin decreased MDR1 what was opposite to knockdown of E-cadherin decreasing MDR1. Our data reveal that knockdown of E-cadherin decreasing MDR1 via HIF-1α is involved in the mechanism of multicellular resistance in colorectal cancer. Though β-catenin is also involved in the mechanism, it does not play a dominant role.

Multidrug resistance characterization in multicellular tumour spheroids from two human lung cancer cell lines

Background

Most of the knowledge about the mechanisms of multidrug resistance in lung cancer has been achieved through the use of cell lines isolated from tumours cultivated either in suspensions of isolated cells or in monolayers and following exposition to different cytostatic agents. However, tumour cell lines growing as multicellular tumour spheroids (MTS) frequently develop multicellular resistance in a drug-independent form. The aim of this study was to characterize the phenotypic and functional differences between two human NSCLC cell lines (INER-37 and INER-51) grown as traditional monolayer cultures versus as MTS.

Methods

After 72 hours treatment with anticancer drugs, chemosensitivity in monolayers and tumour spheroids cultures was assessed using MTT assay. Reverse transcription-polymerase chain reaction was employed to detect the mRNAs of multidrug resistance-related genes. The expression of P-gp was analyzed by immunohistochemical staining and cell cycle profiles were analyzed using FACS.

Results

The results indicate that when grown as MTS each lung cancer cell line had different morphologies as well as and abrogation of cell proliferation with decrease of the G₂/M phase. Also, MTS acquired multicellular resistance to several chemotherapeutic agents in only a few days of culture which were accomplished by significant changes in the expression of MDR-related genes.

Conclusion

Overall, the MTS culture changed the cellular response to drugs nevertheless each of the cell lines studied seems to implement different mechanisms to acquire multicellular resistance.

Chinese medicinal compound delisheng has satisfactory anti-tumor activity, and is associated with up-regulation of endostatin in human hepatocellular carcinoma cell line HepG2 in three-dimensional culture

AIM: To investigate the multicellular resistance of human hepatocellular carcinoma HepG2 cells in three-dimensional culture to delisheng, 5-fluorouracil and adriamycin, and the possible molecular mechanisms of delisheng.

METHODS: Human hepatocellular carcinoma HepG2 cells were cultured with a liquid overlay technique. After the formation of multicellular spheroids, morphology was analyzed by phase contrast microscopy, scanning electron microscopy and transmission electron microscopy. Sensitivity of HepG2 cells to delisheng, 5-fluorouracil and adriamycin was investigated by MTT assay in multicelluar spheroids and monolayers. Vascular endothelial growth factor (VEGF) and endostatin expression were analyzed in multicellular spheroids treated with delisheng, 5-fluorouracil, adriamycin and negative control PBS, with immunohistochemical staining.

RESULTS: Multicellular spheroids exhibited structural characteristics somewhat different to those in monolayers. The cells in three-dimensional cell culture turned out to be less sensitive to delisheng, 5-fluorouracil and adriamycin than the cells cultured in monolayer. This showed that delisheng had a satisfactory cells inhibition ratio compared to 5-fluorouracil and adriamycin. Immunohistochemical staining showed that VEGF and endostatin expression was positive during growth as multicellular spheroids, and endostatin expression in spheroids with treatment of delisheng was higher than that with 5-fluorouracil, adriamycin and PBS (139.35 ± 7.83, 159.23 ± 10.34, 162.83 ± 3.47 and 148.48 ± 11.06, P < 0.05).

CONCLUSION: Chinese medicine compound delisheng has satisfactory anti-tumor activity in HepG2 cells in three-dimensional culture, and the effects are associated with up-regulation of endostatin.