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Expression Pattern of Alternative Splicing Variants of Human Telomerase Reverse Transcriptase (hTERT) in Cancer Cell Lines Was not Associated with the Origin of the Cells.

Khosravi-Maharlooei M, Jaberipour M, Hosseini Tashnizi A, Attar A, Amirmoezi F, Habibagahi M - Int J Mol Cell Med (2015)

Bottom Line: Relative assessment of hTERT expression showed greater expression of the α-deleted variant in the telomerase negative cells (P= 0.04).Those cells possessed the α/β-deleted variant to a smaller extent when compared to the cells with telomerase activity.In spite that, the regulatory roles of hTERT on telomerase activity is still a potential to be utilized as targets for cancer therapies.

View Article: PubMed Central - PubMed

Affiliation: Student Research Committee, Cell and Molecular Medicine Research Group, Shiraz University of Medical Sciences, Shiraz, Iran.

ABSTRACT
Telomerase and systems controlling their activity have been of great attention. There are controversies regarding the role of the alternative splicing forms of the human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase. Therefore, the correlation between telomerase enzyme activity, the abundance of alternatively spliced variants of hTERT and doubling time of a series of cancer cell lines originated from hematopoietic, breast, colorectal, neural, ovarian, lung, kidney, bladder, prostate and head and neck cancers were investigated. Expression levels of four different variants of hTERT (the full length, α-deletion, β-deletion and α/β-deletion) were quantitatively measured by real time PCR. Telomerase activity was determined by the telomerase repeat amplification protocol (TRAP) while doubling time of the cells measured by plotting growth curves. Results showed high diversity in the relative proportions of hTERT transcripts while the majority of the cells expressed the full length variant as the main transcript. Telomerase activity could not be detected in all cells. Relative assessment of hTERT expression showed greater expression of the α-deleted variant in the telomerase negative cells (P= 0.04). Those cells possessed the α/β-deleted variant to a smaller extent when compared to the cells with telomerase activity. Greater association between full length spliced variant and β-variant expression was observed in cells presenting telomerase activity (P= 0.0007, r= 0.74). High degrees of variation among the studied cells regarding the pattern of hTERT expression were present. In spite that, the regulatory roles of hTERT on telomerase activity is still a potential to be utilized as targets for cancer therapies.

No MeSH data available.


Related in: MedlinePlus

Relative expression levels of different hTERT transcript variants in the studied cancer cell lines. The expression of (A) full length, (B) α-deleted variant, (C) β-deleted variant and (D) α/β-deleted variants of hTERT were measured by real time PCR. The expression of the transcripts was compared to β-actin as internal housekeeping gene. All the studied cancer cell lines expressed a mixed pattern of all four hTERT variants
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Figure 3: Relative expression levels of different hTERT transcript variants in the studied cancer cell lines. The expression of (A) full length, (B) α-deleted variant, (C) β-deleted variant and (D) α/β-deleted variants of hTERT were measured by real time PCR. The expression of the transcripts was compared to β-actin as internal housekeeping gene. All the studied cancer cell lines expressed a mixed pattern of all four hTERT variants

Mentions: Quantitative real time PCR with specific primers for different variants of hTERT was set up to detect the expression levels of the hTERT variants in the studied cancer cell lines. Results showed high disparity in the relative proportions of hTERT transcript variants. Figures 3A, 3B, 3C and 3D represent the relative expression levels of the full length, α-deleted, β-deleted and α/β- deleted variants of hTERT in the cells, respectively. All the studied cancer cell lines expressed a combination of all four hTERT variants with no major restriction. When the expression of the variants were analyzed as percentages of the total hTERT messages in each cell lines, it showed that the full length variant in average encompass 56% of the transcripts (range from 22.70% to 98.46%) followed by α-deleted variant (mean 23%, range from 0.3%- 52%). The  β-deleted variant and α/β-deleted variant on average made up only 20% of hTERT expression in the studied cell lines. Table 3 lists the most prevalent hTERT variants expressed in the cell lines. As it is shown, the full length hTERT was the most predominant variant in the majority of the cells. Therefore, the ratios of expression level of this variant over the alternative spliced forms were measured to compare the hTERT composition of the cells. The median folds of excess expression of full length variant over the expression levels of α-deleted, β-deleted and α/β-deleted variants in the studied cells were 2.84, 3.7 and 31.7, respectively.


Expression Pattern of Alternative Splicing Variants of Human Telomerase Reverse Transcriptase (hTERT) in Cancer Cell Lines Was not Associated with the Origin of the Cells.

Khosravi-Maharlooei M, Jaberipour M, Hosseini Tashnizi A, Attar A, Amirmoezi F, Habibagahi M - Int J Mol Cell Med (2015)

Relative expression levels of different hTERT transcript variants in the studied cancer cell lines. The expression of (A) full length, (B) α-deleted variant, (C) β-deleted variant and (D) α/β-deleted variants of hTERT were measured by real time PCR. The expression of the transcripts was compared to β-actin as internal housekeeping gene. All the studied cancer cell lines expressed a mixed pattern of all four hTERT variants
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4499573&req=5

Figure 3: Relative expression levels of different hTERT transcript variants in the studied cancer cell lines. The expression of (A) full length, (B) α-deleted variant, (C) β-deleted variant and (D) α/β-deleted variants of hTERT were measured by real time PCR. The expression of the transcripts was compared to β-actin as internal housekeeping gene. All the studied cancer cell lines expressed a mixed pattern of all four hTERT variants
Mentions: Quantitative real time PCR with specific primers for different variants of hTERT was set up to detect the expression levels of the hTERT variants in the studied cancer cell lines. Results showed high disparity in the relative proportions of hTERT transcript variants. Figures 3A, 3B, 3C and 3D represent the relative expression levels of the full length, α-deleted, β-deleted and α/β- deleted variants of hTERT in the cells, respectively. All the studied cancer cell lines expressed a combination of all four hTERT variants with no major restriction. When the expression of the variants were analyzed as percentages of the total hTERT messages in each cell lines, it showed that the full length variant in average encompass 56% of the transcripts (range from 22.70% to 98.46%) followed by α-deleted variant (mean 23%, range from 0.3%- 52%). The  β-deleted variant and α/β-deleted variant on average made up only 20% of hTERT expression in the studied cell lines. Table 3 lists the most prevalent hTERT variants expressed in the cell lines. As it is shown, the full length hTERT was the most predominant variant in the majority of the cells. Therefore, the ratios of expression level of this variant over the alternative spliced forms were measured to compare the hTERT composition of the cells. The median folds of excess expression of full length variant over the expression levels of α-deleted, β-deleted and α/β-deleted variants in the studied cells were 2.84, 3.7 and 31.7, respectively.

Bottom Line: Relative assessment of hTERT expression showed greater expression of the α-deleted variant in the telomerase negative cells (P= 0.04).Those cells possessed the α/β-deleted variant to a smaller extent when compared to the cells with telomerase activity.In spite that, the regulatory roles of hTERT on telomerase activity is still a potential to be utilized as targets for cancer therapies.

View Article: PubMed Central - PubMed

Affiliation: Student Research Committee, Cell and Molecular Medicine Research Group, Shiraz University of Medical Sciences, Shiraz, Iran.

ABSTRACT
Telomerase and systems controlling their activity have been of great attention. There are controversies regarding the role of the alternative splicing forms of the human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase. Therefore, the correlation between telomerase enzyme activity, the abundance of alternatively spliced variants of hTERT and doubling time of a series of cancer cell lines originated from hematopoietic, breast, colorectal, neural, ovarian, lung, kidney, bladder, prostate and head and neck cancers were investigated. Expression levels of four different variants of hTERT (the full length, α-deletion, β-deletion and α/β-deletion) were quantitatively measured by real time PCR. Telomerase activity was determined by the telomerase repeat amplification protocol (TRAP) while doubling time of the cells measured by plotting growth curves. Results showed high diversity in the relative proportions of hTERT transcripts while the majority of the cells expressed the full length variant as the main transcript. Telomerase activity could not be detected in all cells. Relative assessment of hTERT expression showed greater expression of the α-deleted variant in the telomerase negative cells (P= 0.04). Those cells possessed the α/β-deleted variant to a smaller extent when compared to the cells with telomerase activity. Greater association between full length spliced variant and β-variant expression was observed in cells presenting telomerase activity (P= 0.0007, r= 0.74). High degrees of variation among the studied cells regarding the pattern of hTERT expression were present. In spite that, the regulatory roles of hTERT on telomerase activity is still a potential to be utilized as targets for cancer therapies.

No MeSH data available.


Related in: MedlinePlus