Leptin upregulates telomerase activity and transcription of human telomerase reverse transcriptase in MCF-7 breast cancer cells

Telomerase is known to contribute to telomere maintenance and to provide cancer cell immortality. However, numerous reports are showing that the function of the enzyme goes far beyond chromosome ends. The study aimed to explore how telomerase downregulation in MCF7 and MDA-MB-231 breast cancer cells affects their ability to survive. Consequently, sensitivity to drug resistance, proliferation, and adhesion were assessed. The lentiviral-mediated human telomerase reverse transcriptase (hTERT) downregulation efficiency was performed at gene expression and protein level using qPCR and Western blot, respectively. Telomerase activity was evaluated using the Telomeric Repeat Amplification Protocol (TRAP) assay. The study revealed that hTERT downregulation led to an increased sensitivity of breast cancer cells to doxorubicin which was demonstrated in MTT and clonogenic assays. During a long-term doubling time assessment, a decreased population doubling level was observed. Interestingly, it did not dramatically affect cell cycle distribution. hTERT downregulation was accompanied by an alteration in β1-integrin- and by focal adhesion kinase (FAK)-driven pathways together with the reduction of target proteins phosphorylation, i.e., paxillin and c-Src. Additionally, autophagy activation was observed in MDA-MB-231 cells manifested by alternations in Atg5, Beclin 1, LC3II/I ratio, and p62. These results provide new evidence supporting the possible therapeutic potential of telomerase downregulation leading to induction of autophagy and cancer cells elimination.

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Selective Apoptosis and Growth Impairment of Cancer Cells Induced by Human Telomerase Reverse Transcriptase (hTERT) Targeting Artificial MicroRNA

Science of Advanced Materials ◽

10.1166/sam.2021.4090 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1644-1656

Author(s):

Hongjun Lin ◽

Pengliang Xin ◽

Huangen Li ◽

Mingqing Tang

Keyword(s):

Reverse Transcriptase ◽

Cancer Cells ◽

Telomerase Activity ◽

Telomerase Reverse Transcriptase ◽

Human Telomerase Reverse Transcriptase ◽

Reverse Transcription Pcr ◽

Angiogenesis Assay ◽

Amplification Protocol ◽

Huvec Cells ◽

Human Telomerase

Human telomerase reverse transcriptase (hTERT) is a promising cancer target, and amiRNA particle displays the siRNA’s specificity and miRNA’s safety, suggesting that cancers can be treated more effective and safely by hTERT targeting amiRNA particles. Hela, NCI-H446, U2-OS and Huvec cells were transfected by hTERT targeting amiRNA particles. hTERT expression, telomerase activity and cell viability were evaluated by quantitative reverse transcription-PCR (qRT-PCR), western blot (WB), telomeric repeat amplification protocol (TRAP) assays, MTT method, transwell protocol, fluorescence-activated cell sorting (FACS) technologies, angiogenesis assay, and xenograft tumor models. Results: hTERT expression and telomerase activity in Hela and NCIH446 were significantly inhibited by amiRNA. Anti-proliferation and pro-apoptosis effects were only observed in transfected Hela and NCI-H446 cells, but anti-migration and anti-angiogenesis effects were presented in transfected Huvec cells. More interestingly, low to 1.56 nM amiRNA can inhibit the proliferation of Hela cells by 80.99±5.24%. Conclusion: amiRNA selectively and effectively impairs the growth, and assists the apoptosis of telomerase-positive cancer cells.

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