Overexpression of Beclin1 gene leads to reduction of telomerase activity in MDCK cells and enhances apoptosis.

BACKGROUND: Telomeres through maintaining chromosomal integrity have key roles in the cell life span. The autophagy is typically a pro-survival process and important for maintaining cellular homeostasis. Conversely, in some conditions, autophagy acts as caspase-independent cell death program. Beclin1 gene plays a principal role in the initiation of autophagy. OBJECTIVE: The aim of this study was to evaluate the effect of autophagy induction via recombinant Beclin1 on telomerase activity and programmed cell death (apoptosis) in MCDK cells. MATERIALS AND METHODS: The recombinant Beclin1-pcDNA3.1(-) was transfected into MDCK cells. Next, the autophagy information was detected by LC3II staining as autophagy marker using flow cytometry. The telomerase activity was measured by telomeric repeat amplification protocol method in MDCK cells. To detection of the cell death in MDCK cells, apoptosis assay was done through Annexin V staining method. RESULTS: The results of flow cytometry analysis indicated that following overexpression of Beclin1 gene, the percentage of the LC3II was 16.08% compared with control group (0.48%). Following induction of autophagy, telomerase activity reduced 10 folds in comparison with the control group. The rate of apoptosis in transfected MDCK cells increased up to 12.74%. CONCLUSION: Crosstalk between telomerase, autophagy, and apoptosis may determine the fate of the cancer cell aging. Hence, manipulation of autophagy may create a novel area to design new compounds and combination therapy to shorten the cancer cell survival.

Autophagy induction reduces telomerase activity in HeLa cells.

Autophagy is a cellular homeostatic process whereby damaged proteins and organelles are encapsulated into double membrane vesicles, called autophagosomes, for lysosomal digestion. Beclin1 plays a key role in the initial steps of autophagosome formation. In this study, we evaluated the effect of Beclin 1 overexpression in induction of autophagy and the relationship between autophagy induction and telomerase activity in HeLa cells. We found that overexpression of Beclin 1 in HeLa cells leads to autophagosome formation as shown by intracellular autophagosomal marker LC3-II staining. Expression of Beclin1 reduced telomerase activity for about 100 fold compared with the control while it did not affect TERT expression level. The results of cell cycle analysis indicated that the cell cycle and proliferation progressed normally up to 48h post-transfection. Understanding the role of autophagy induction and telomerase in the pathophysiology of aging and human cancer reveal new strategies that hold much promise for intervention and therapeutic uses.

Correlation between antioxidant activity of garlic extracts and WEHI-164 fibrosarcoma tumor growth in BALB/c mice.

The biological activities of garlic may be affected by different processing methods. This study, therefore, aimed to evaluate potential anticancer effects of different type of processed garlic extracts on WEHI-164 tumor cells in inbred BALB/c mice and correlate the tumor growth rates with some garlic constituents. In a preclinical trial 60 BALB/c mice were injected with WEHI-164 tumor cells and divided into six groups of 10 animals. Group 1 mice received 200 µL of saline, and groups 2-6 were injected intraperitoneally with fresh, microwaved, 3-month-old, leaves, and boiled garlic extracts, respectively, at 20 mg/kg/0.2 mL. Three weeks following tumor inoculation, the mean tumor size in garlic extract-treated groups was reduced with significant reductions observed in the fresh and microwaved extract groups compared with the control group (P<.05). The antioxidant capacity and the amounts of allicin, flavonoids, and phenolic compounds in differentially processed garlic were evaluated and correlated with their anticancer activities. There was a linear correlation between the amounts of allicin, flavonoids, or phenolic components derived from fresh, microwaved, 3-month-old, leaves, and boiled garlic and cancer growth prevention. In conclusion, garlic has anticancer activity against WEHI-164 tumor cells, and processing such as heating reduces its effect dramatically. The anticancer activities of different kinds of garlic are related to the level of allicin, flavonoids, and phenolic components. Therefore, fresh garlic has the highest content of bioactive components and the greatest anticancer efficacy.