hTERT-targeted RNA interference inhibits tumorigenicity and motility of HCT116 cells

Abstract

Telomerase is proposed as an anticancer target. Increasing evidence suggests that telomerase is involved in functions independent of telomere-extension activity. In this study, we designed a small interfering RNA (siRNA) targeting human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase. Using transient and persistent transfection of hTERT siRNA into telomerase-positive human colon carcinoma HCT116 cells, we demonstrated that hTERT siRNA suppresses hTERT expression and leads to inhibition of telomerase activity and HCT116 cell growth and in vivo tumorigenicity in nude mice. Further analysis indicated that depletion of hTERT reduces cell adhesion, migration, and invasion prior to inhibition of cell proliferation. Downregulation of hTERT also decreased the expression levels of adhesion-and motility-related proteins, in particular c-Met and integrins. The lack of detectable changes in telomere length showed that downregulation of hTERT in the present system had no significant effect on telomere-extension activity. Taken together, our results highlight the therapeutic potential of a novel hTERT siRNA and suggest that hTERT is involved in the regulation of cell motility in a telomere-independent manner.

Silencing of the hTERT Gene by shRNA Inhibits Colon Cancer SW480 Cell Growth In Vitro and In Vivo

“…Our findings confirm and extend similar work in the HCT116 human colorectal cancer cell line [29], in which the authors used a different sequence than ours to knock-down hTERT expression by RNAi; this inhibited telomerase activity and cell growth in cultures and in HCT116 tumors in nude mice. We wished to study the cellular effects of hTERT inhibition in SW480 cells in even more detail, so we examined apoptosis levels in cultures by electron microscopy, TUNEL assay and MMP measurement, as well as in SW480 tumors by TUNEL assay.…”

“…We wished to study the cellular effects of hTERT inhibition in SW480 cells in even more detail, so we examined apoptosis levels in cultures by electron microscopy, TUNEL assay and MMP measurement, as well as in SW480 tumors by TUNEL assay. Our results in SW480 cells, together with those in HCT116 cells [29], indicate that colon cancer should be added to the list of malignancies that can be inhibited by RNAi targeting hTERT in vitro and in vivo; this list already includes lung cancer, oral squamous cell carcinoma, erythroleukemia, hepatocellular carcinoma, cervical epithelial squamous cancer, and gastric cancer [30]–[34], [29]. Our SW480 model system may prove particularly useful for further therapeutic research because the cells are derived from advanced (grade 3–4) colon adenocarcinoma, they are fairly homogeneous (mostly epithelial cells), they produce carcinoembryonic antigen (CEA), and they express hTERT mRNA at high levels.…”

Human telomerase reverse transcriptase regulates cyclin D1 and G1/S phase transition in laryngeal squamous carcinoma

“…Its main role is to maintain the stability of length and structure of telomere in eukaryotic cells [1][2][3]. Many studies have shown that small-interfering RNA (siRNA) targeting human telomerase reverse transcriptase (hTERT) could inhibit telomerase activity and cell viability in cancer cells [4][5][6]. Those effects are partially due to telomere attrition when the hTERT and telomerase activity is suppressed, especially in the long term.…”

Positive association of long telomeres with the invasive capacity of hepatocellular carcinoma cells

“…The canonical role of telomerase is to add telomeric DNA repeats for telomere elongation [20]. Moreover, the effects of silencing or overexpressing TERT on tumor cell invasion have been reported [20,21]. However, there have been no studies on the association between telomere length and invasion using a cell culture system.…”