TY - JOUR
T1 - Walnut phenolic extracts reduce telomere length and telomerase activity in a colon cancer stem cell model
AU - Shin, Phil Kyung
AU - Zoh, Yoonchae
AU - Choi, Jina
AU - Kim, Myung Sunny
AU - Kim, Yuri
AU - Choi, Sang Woon
N1 - Publisher Copyright:
© 2019 The Korean Nutrition Society and the Korean Society of Community Nutrition.
PY - 2019/2
Y1 - 2019/2
N2 - BACKGROUND/OBJECTIVES: Telomeres are located at the chromosomal ends and progressively shortened during each cell cycle. Telomerase, which is regulated by hTERT and c-MYC, maintains telomeric DNA sequences. Especially, telomerase is active in cancer and stem cells to maintain telomere length for replicative immortality. Recently we reported that walnut phenolic extract (WPE) can reduce cell viability in a colon cancer stem cell (CSC) model. We, therefore, investigated the effect of WPE on telomere maintenance in the same model. MATERIALS AND METHODS: CD133 + CD44 + cells from HCT116, a human colon cancer cell line, were sorted by Fluorescence-activated cell sorting (FACS) and treated with WPE at the concentrations of 0, 10, 20, and 40 µg/mL for 6 days. Telomere lengths were assessed by quantitative real-time PCR (qRT-PCR) using telomere specific primers and DNA extracted from the cells, which was further adjusted with single-copy gene and reference DNA (ddC t ). Telomerase activity was also measured by qRT-PCR after incubating the PCR mixture with cell protein extracts, which was adjusted with reference DNA (dC t ). Transcriptions of hTERT and c-MYC were determined using conventional RT-PCR. RESULTS: Telomere length of WPE-treated cells was significantly decreased in a dose-dependent manner (5.16 ± 0.13 at 0 µg/mL, 4.79 ± 0.12 at 10 µg/mL, 3.24 ± 0.08 at 20 µg/mL and 3.99 ± 0.09 at 40 µg/mL; P = 0.0276). Telomerase activities concurrently decreased with telomere length (1.47 ± 0.04, 1.09 ± 0.01, 0.76 ± 0.08, and 0.88 ± 0.06; P = 0.0067). There was a positive correlation between telomere length and telomerase activity (r = 0.9090; P < 0.0001). Transcriptions of both hTERT and c-MYC were also significantly decreased in the same manner. CONCLUSION: In the present cell culture model, WPE reduced telomere maintenance, which may provide a mechanistic link to the effect of walnuts on the viability of colon CSCs.
AB - BACKGROUND/OBJECTIVES: Telomeres are located at the chromosomal ends and progressively shortened during each cell cycle. Telomerase, which is regulated by hTERT and c-MYC, maintains telomeric DNA sequences. Especially, telomerase is active in cancer and stem cells to maintain telomere length for replicative immortality. Recently we reported that walnut phenolic extract (WPE) can reduce cell viability in a colon cancer stem cell (CSC) model. We, therefore, investigated the effect of WPE on telomere maintenance in the same model. MATERIALS AND METHODS: CD133 + CD44 + cells from HCT116, a human colon cancer cell line, were sorted by Fluorescence-activated cell sorting (FACS) and treated with WPE at the concentrations of 0, 10, 20, and 40 µg/mL for 6 days. Telomere lengths were assessed by quantitative real-time PCR (qRT-PCR) using telomere specific primers and DNA extracted from the cells, which was further adjusted with single-copy gene and reference DNA (ddC t ). Telomerase activity was also measured by qRT-PCR after incubating the PCR mixture with cell protein extracts, which was adjusted with reference DNA (dC t ). Transcriptions of hTERT and c-MYC were determined using conventional RT-PCR. RESULTS: Telomere length of WPE-treated cells was significantly decreased in a dose-dependent manner (5.16 ± 0.13 at 0 µg/mL, 4.79 ± 0.12 at 10 µg/mL, 3.24 ± 0.08 at 20 µg/mL and 3.99 ± 0.09 at 40 µg/mL; P = 0.0276). Telomerase activities concurrently decreased with telomere length (1.47 ± 0.04, 1.09 ± 0.01, 0.76 ± 0.08, and 0.88 ± 0.06; P = 0.0067). There was a positive correlation between telomere length and telomerase activity (r = 0.9090; P < 0.0001). Transcriptions of both hTERT and c-MYC were also significantly decreased in the same manner. CONCLUSION: In the present cell culture model, WPE reduced telomere maintenance, which may provide a mechanistic link to the effect of walnuts on the viability of colon CSCs.
KW - Colonic neoplasms
KW - Stem cells
KW - Telomerase
KW - Telomere
KW - Walnut
UR - http://www.scopus.com/inward/record.url?scp=85063515959&partnerID=8YFLogxK
U2 - 10.4162/nrp.2019.13.1.58
DO - 10.4162/nrp.2019.13.1.58
M3 - Article
AN - SCOPUS:85063515959
SN - 1976-1457
VL - 13
SP - 58
EP - 63
JO - Nutrition Research and Practice
JF - Nutrition Research and Practice
IS - 1
ER -