Inhibitory effect and mechanism of metformin on human ovarian cancer cells SKOV-3 and A2780

OBJECTIVE

Ovarian cancer is the most common malignant tumor in female reproductive system. Metformin is an orally taken hypoglycemic agent, which is extensively applied in the clinic. Clinical trials find that there may be a certain degree of action of the metformin in inhibiting malignant tumors. This paper aims to investigate the inhibitory effect and mechanism of metformin on human ovarian cancer cells.

MATERIALS AND METHODS

Through in vitro cell experiment, the influences of metformin on the proliferation, colony formation and apoptosis of ovarian carcinoma cells were studied. Ovarian cancer cells SKOV-3 and A2780 in logarithmic growth phase were selected and cell proliferation was measured by MTT method. The metformin was processed for 48 h to calculate the survival rate of cells. Also, metformin was processed for 24 h and two weeks or stained with crystal violet, after which Quantity One (Bio-Rad, Hercules, CA, USA) method was used to quantitatively analyze the cell clone formation, meanwhile, the FCM (flow cytometry) was used for the detection and analysis.

RESULTS

Intervened by metformin with different concentrations for 48 h, the cell viabilities of SKOV-3 and A2780 cells were respectively reduced by 19.49 ± 2.92%, 45.41 ± 7.95%, 53.84 ± 5.53%, 64.04 ± 4.36% and 11.45 ± 3.12%, 35.42 ± 7.55%, 43.77 ± 5.77%, 53.05 ± 5.55% as compared with that in the control group with statistical significances. After processed by metformin with different concentrations for two weeks, the cells clone numbers of SKOV-3 and A2780 were significantly reduced. Treatment of metformin on SKOV-3 and A2780 cells of human ovarian cancer showed significant apoptosis.

CONCLUSIONS

The metformin has the inhibitory effect on the cells of human ovarian cancer, which may be through inducing ovarian cancer cell apoptosis.

Importance of CD44 on umbilical cord mesenchymal stem cells for expansion of hematopoietic cells

Human umbilical cord mesenchymal stem cells (hUCMSCs) have important functions on the expansion of hematopoietic stem cells (HSCs) through providing the essential microenvironment for hematopoiesis. In order to test whether CD44 on hUCMSCs could have a key function for the ability of hUCMSCs to expand human HSCs, the soluble anti—CD44 antibody was added to the co—cultures of hUCMSCs and cord blood (CB) CD34+ cells, which blocked the ability of hUCMSCs to expand CB CD34+ cells significantly. Long—term culture initiating cell (LTC—IC) assay revealed that the ability of multipotent differentiation of CB CD34+ cells co—cultured with CD44 knockdown hUCMSCs could only retain lasting at most for 5 weeks in vitro. In vivo assay, based on non—obese diabetic/severe combined immunodeficient disease (NOD/SCID) mice, revealed that the hematopoietic reconstitution potential of CB CD34+ cells co—cultured with CD44 knockdown hUCMSCs is significantly reduced. The hematopoietic supporting ability of hUCMSCs in vivo and in vitro is reduced upon the knockdown of CD44. CD44 has important functions on the ability of hUCMSCs to expand human HSCs in the cell— extrinsic control.

Effect of insulin on oxygen free radicals and oxidative phosphorylation in liver mitochondria of diabetic rats

AIM

To observe the effects of insulin on liver mitochondrial respiratory function, activity of H+-ATPase, and superoxide anion free radicals production in diabetic rats.

METHODS

Rats were injected iv with alloxan 40 mg/kg to induce diabetes. The liver mitochondrial respiratory function was assayed by measurement of oxygen consumption using a Clark oxygen electrode. Superoxide anion production was assayed using chemiluminescence method. Activities of H+-ATPase were measured by luciferin-luciferase system and inorganic phosphorus's method.

RESULTS

Insulin 1 U/kg sc daily for 9 weeks improved oxidative phosphorylation, respiratory rate state 3 (P < 0.05), respiratory control ration (P < 0.01), and ADP:O ratio (P < 0.01), but there were no obvious effect on respiratory rate state 4 (P > 0.05). In the insulin group, synthesis activity of H+-ATPase was obviously increased (P < 0.05) and hydrolytic activity of H+-ATPase was remarkably decreased (P < 0.01), compared with the diabetes group. Insulin 1 U/kg for 9 weeks apparently decreased the production of O2.- (P < 0.01) in liver mitochondria of diabetic rats.

CONCLUSION

Insulin can prevent the injury from superoxide anion in liver mitochondria, and improve the function of the liver mitochondria oxidative phosphorylation.

Rapid assay of A1c-type glycosylated hemoglobin in blood of diabetic rats using fast protein liquid chromatography

AIM

To develop a fast protein liquid chromatography (FPLC) method for the assay of Alc-type glycosylated hemoglobin in diabetic rats.

METHODS

Venous blood was collected from rats. After the erythrocytes were washed and sedimented, the hemolysate was prepared and diluted with isotonic saline as a sample for the assay. Samples were then separated on Mono_S_HR_5/5 cation exchange column by a lithium chloride gradient elution system. The Alc-type glycosylated hemoglobin was monitored by measuring the absorbance at 415 nm.

RESULTS

The Alc-type glycosylated hemoglobin was well separated from total hemoglobin. The average HbAlc amount in diabetic rats was determined to be (3.6% +/- 0.6%, n = 7), while the corresponding figure in normal rats was (1.4% +/- 0.4%, n = 7, P < 0.01).

CONCLUSION

This FPLC method is easy, rapid and reproducible, and can be used for an assay of diabetic rat HbAlc to evaluate and screen new drugs for diabetes mellitus therapy.