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Independent overexpression of the subunits of translation elongation factor complex eEF1H in human lung cancer.

Veremieva M, Kapustian L, Khoruzhenko A, Zakharychev V, Negrutskii B, El'skaya A - BMC Cancer (2014)

Bottom Line: The components of translation elongation complex eEF1H (eEF1A, eEF1Bα, eEF1Bβ, eEF1Bγ) were found overexpressed in different cancers.Nuclear localization of eEF1Bβ in the cancer rather than distal normal looking tissues was found.In cancer tissue, eEF1A and eEF1Bα were not found in nuclei while all four subunits of eEF1H demonstrated both cytoplasmic and nuclear appearance in the lung carcinoma cell line A549.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Molecular and Cellular Biology, Institute of Molecular Biology and Genetics NASU, 150 Acad,Zabolotnogo Str,, Kiev 03680, Ukraine. negrutskii@imbg.org.ua.

ABSTRACT

Background: The constituents of stable multiprotein complexes are known to dissociate from the complex to play independent regulatory roles. The components of translation elongation complex eEF1H (eEF1A, eEF1Bα, eEF1Bβ, eEF1Bγ) were found overexpressed in different cancers. To gain the knowledge about novel cancer-related translational mechanisms we intended to reveal whether eEF1H exists as a single unit or independent subunits in different human cancers.

Methods: The changes in the expression level of every subunit of eEF1H in the human non-small-cell lung cancer tissues were examined. The localization of eEF1H subunits was assessed by immunohistochemistry methods, subcellular fractionation and confocal microscopy. The possibility of the interaction between the subunits was estimated by co-immunoprecipitation.

Results: The level of eEF1Bβ expression was increased more than two-fold in 36%, eEF1Bγ in 28%, eEF1A in 20% and eEF1Bα in 8% of tumor specimens. The cancer-induced alterations in the subunits level were found to be uncoordinated, therefore the increase in the level of at least one subunit of eEF1H was observed in 52% of samples. Nuclear localization of eEF1Bβ in the cancer rather than distal normal looking tissues was found. In cancer tissue, eEF1A and eEF1Bα were not found in nuclei while all four subunits of eEF1H demonstrated both cytoplasmic and nuclear appearance in the lung carcinoma cell line A549. Unexpectedly, in the A549 nuclear fraction eEF1A lost the ability to interact with the eEF1B complex.

Conclusions: The results suggest independent functioning of some fraction of the eEF1H subunits in human tumors. The absence of eEF1A and eEF1B interplay in nuclei of A549 cells is a first evidence for non-translational role of nuclear-localized subunits of eEF1B. We conclude the appearance of the individual eEF1B subunits in tumors is a more general phenomenon than appreciated before and thus is a novel signal of cancer-related changes in translation apparatus.

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Comparison of the level of different subunits of eEF1H in human lung carcinoma and normal lung. Representative Western blots are shown. N – normal tissue, T – tumor tissue. Molecular weights: eEF1A ~50 kDa, eEF1Bα ~28 kDa, eEF1Bβ ~35 kDa, eEF1Bγ ~51 kDa, β-actin ~42 kDa. Numeration of samples is according to Table 1.
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Fig2: Comparison of the level of different subunits of eEF1H in human lung carcinoma and normal lung. Representative Western blots are shown. N – normal tissue, T – tumor tissue. Molecular weights: eEF1A ~50 kDa, eEF1Bα ~28 kDa, eEF1Bβ ~35 kDa, eEF1Bγ ~51 kDa, β-actin ~42 kDa. Numeration of samples is according to Table 1.

Mentions: The protein content of eEF1 subunits was examined in the same tumor samples by Western blot analysis. A representative experiment is shown in Figure 2. Independent ≥ 2-fold overexpression of at least one eEF1 component was detected in 52% of all tumor specimens (Table 1). A substantial cancer-related elevation was observed for the eEF1Bβ (36%) and eEF1Bγ (28%) subunits. We did not observe any significant changes in the eEF1Bα protein level. In fact, eEF1Bα increased ≥ 2-fold only in two clinical samples out of 25.Figure 2


Independent overexpression of the subunits of translation elongation factor complex eEF1H in human lung cancer.

Veremieva M, Kapustian L, Khoruzhenko A, Zakharychev V, Negrutskii B, El'skaya A - BMC Cancer (2014)

Comparison of the level of different subunits of eEF1H in human lung carcinoma and normal lung. Representative Western blots are shown. N – normal tissue, T – tumor tissue. Molecular weights: eEF1A ~50 kDa, eEF1Bα ~28 kDa, eEF1Bβ ~35 kDa, eEF1Bγ ~51 kDa, β-actin ~42 kDa. Numeration of samples is according to Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4265501&req=5

Fig2: Comparison of the level of different subunits of eEF1H in human lung carcinoma and normal lung. Representative Western blots are shown. N – normal tissue, T – tumor tissue. Molecular weights: eEF1A ~50 kDa, eEF1Bα ~28 kDa, eEF1Bβ ~35 kDa, eEF1Bγ ~51 kDa, β-actin ~42 kDa. Numeration of samples is according to Table 1.
Mentions: The protein content of eEF1 subunits was examined in the same tumor samples by Western blot analysis. A representative experiment is shown in Figure 2. Independent ≥ 2-fold overexpression of at least one eEF1 component was detected in 52% of all tumor specimens (Table 1). A substantial cancer-related elevation was observed for the eEF1Bβ (36%) and eEF1Bγ (28%) subunits. We did not observe any significant changes in the eEF1Bα protein level. In fact, eEF1Bα increased ≥ 2-fold only in two clinical samples out of 25.Figure 2

Bottom Line: The components of translation elongation complex eEF1H (eEF1A, eEF1Bα, eEF1Bβ, eEF1Bγ) were found overexpressed in different cancers.Nuclear localization of eEF1Bβ in the cancer rather than distal normal looking tissues was found.In cancer tissue, eEF1A and eEF1Bα were not found in nuclei while all four subunits of eEF1H demonstrated both cytoplasmic and nuclear appearance in the lung carcinoma cell line A549.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Molecular and Cellular Biology, Institute of Molecular Biology and Genetics NASU, 150 Acad,Zabolotnogo Str,, Kiev 03680, Ukraine. negrutskii@imbg.org.ua.

ABSTRACT

Background: The constituents of stable multiprotein complexes are known to dissociate from the complex to play independent regulatory roles. The components of translation elongation complex eEF1H (eEF1A, eEF1Bα, eEF1Bβ, eEF1Bγ) were found overexpressed in different cancers. To gain the knowledge about novel cancer-related translational mechanisms we intended to reveal whether eEF1H exists as a single unit or independent subunits in different human cancers.

Methods: The changes in the expression level of every subunit of eEF1H in the human non-small-cell lung cancer tissues were examined. The localization of eEF1H subunits was assessed by immunohistochemistry methods, subcellular fractionation and confocal microscopy. The possibility of the interaction between the subunits was estimated by co-immunoprecipitation.

Results: The level of eEF1Bβ expression was increased more than two-fold in 36%, eEF1Bγ in 28%, eEF1A in 20% and eEF1Bα in 8% of tumor specimens. The cancer-induced alterations in the subunits level were found to be uncoordinated, therefore the increase in the level of at least one subunit of eEF1H was observed in 52% of samples. Nuclear localization of eEF1Bβ in the cancer rather than distal normal looking tissues was found. In cancer tissue, eEF1A and eEF1Bα were not found in nuclei while all four subunits of eEF1H demonstrated both cytoplasmic and nuclear appearance in the lung carcinoma cell line A549. Unexpectedly, in the A549 nuclear fraction eEF1A lost the ability to interact with the eEF1B complex.

Conclusions: The results suggest independent functioning of some fraction of the eEF1H subunits in human tumors. The absence of eEF1A and eEF1B interplay in nuclei of A549 cells is a first evidence for non-translational role of nuclear-localized subunits of eEF1B. We conclude the appearance of the individual eEF1B subunits in tumors is a more general phenomenon than appreciated before and thus is a novel signal of cancer-related changes in translation apparatus.

Show MeSH
Related in: MedlinePlus