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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

Telomerase enzyme activity in the cells was quantified by TRAP assay. The majority of the cells showed varying degrees of telomerase enzyme activity; however, four cell lines of different tissue origins failed to do that
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Figure 4: Telomerase enzyme activity in the cells was quantified by TRAP assay. The majority of the cells showed varying degrees of telomerase enzyme activity; however, four cell lines of different tissue origins failed to do that

Mentions: TRAP assay was used to measure telomerase activity in the studied cell lines. Figure 4 demonstrates the corresponding quantities. As shown, significant telomerase activity could be detected in most cancer cells (80%); however, telomerase activity in four of the cancer cell lines, SKBR3, MCF-7, Calu6 and A172 could not be detected. To compare the expression levels of different variants in the cells with and without telomerase activity, the relative expression levels of full length transcript over the expression levels of other variants were determined. In the cells with detectable telomerase activity the mean folds increase in the expression of the full length variant over the α-deleted, β-deleted and α/β-deleted variants were 2.01, 3.10 and 4.40 respectively. The relative expression levels of full length transcript over the other variants in the cells without telomerase activity were 0.68, 4.61 and 10.17, respectively. The differences for α- deleted and α/β- deleted variants between the two cell groups were statistically significant (P<0.001 and P<0.005, 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)

Telomerase enzyme activity in the cells was quantified by TRAP assay. The majority of the cells showed varying degrees of telomerase enzyme activity; however, four cell lines of different tissue origins failed to do that
© Copyright Policy
Related In: Results  -  Collection

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

Figure 4: Telomerase enzyme activity in the cells was quantified by TRAP assay. The majority of the cells showed varying degrees of telomerase enzyme activity; however, four cell lines of different tissue origins failed to do that
Mentions: TRAP assay was used to measure telomerase activity in the studied cell lines. Figure 4 demonstrates the corresponding quantities. As shown, significant telomerase activity could be detected in most cancer cells (80%); however, telomerase activity in four of the cancer cell lines, SKBR3, MCF-7, Calu6 and A172 could not be detected. To compare the expression levels of different variants in the cells with and without telomerase activity, the relative expression levels of full length transcript over the expression levels of other variants were determined. In the cells with detectable telomerase activity the mean folds increase in the expression of the full length variant over the α-deleted, β-deleted and α/β-deleted variants were 2.01, 3.10 and 4.40 respectively. The relative expression levels of full length transcript over the other variants in the cells without telomerase activity were 0.68, 4.61 and 10.17, respectively. The differences for α- deleted and α/β- deleted variants between the two cell groups were statistically significant (P<0.001 and P<0.005, 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