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PARN Knockdown in Cell Lines Results in Differential and Cell-Specific Alterations in the Expression of
Nishith Babu1, Dechamma Pandyanda Nanjappa1, Sandra Nazareth2
1Division of Molecular Genetics and Cancer, Nitte University Centre for Science Education and Research (NUCSER), NITTE (Deemed to be University), Deralakatte, Mangaluru, Karnataka, India.
Abstract:
Ribonucleases (RNases) is the collective term used for the group of enzymes that are involved in mRNA degradation. The shortening of the poly (A) tail through deadenylation is the preferred mechanism of degradation of most eukaryotic mRNAs and poly (A)-specific ribonuclease (PARN) is the most important player in deadenylation. Besides its primarily role in mRNA stability, PARN is also involved in several non-conventional functions. It is conceivable that a decreased RNase activity can alter the stability of cancer-associated mRNAs and this alteration may be differential in cells of different origin.
Methods:
The effects of siRNA-mediated knockdown of PARN on the post-transcriptional expression of 16 oncogenes and 18 tumor suppressor genes in cells derived from different lineages (NCI-H460 and NCI-H522; lung cancer) and (HEK-293; kidney) were investigated. Further, the effects of PARN depletion on proliferation and death of the lung cancer cells were investigated.
Results:
Quantitative real time PCR analysis revealed an cell-specific alteration in the expression of the target onco and tumor suppressor genes upon PARN depletion, differently, for cells derived from different lineages. The tumor suppressor genes showed a consistent pattern of down regulation upon PARN depletion in all the three cell types tested. In contrast, the expression of oncogenes was not consistent; while some oncogenes showed overexpression in HEK 293 cells, the majority of them were downregulated in the lung cancer cells. Further, PARN depletion did not alter the proliferation of lung cancer cells, which was in contrast to previous reports.
Conclusion:
The results of this study reveal that PARN deficiency leads to an altered stability of cancer-associated mRNA, distinctly, in cells of different lineages. Despite previous reports suggesting a potential therapeutic role of PARN in cancer, our results suggest that PARN may not be an important biomarker, particularly in lung cancer.
Insights
Poly (A)-specific ribonuclease (PARN) depletion alters cancer-associated mRNA stability differently across cell types. PARN deficiency may not be a significant biomarker, especially in lung cancer.
Area of Science:
- Molecular Biology
- Gene Regulation
- Cancer Research
Background:
- Ribonucleases (RNases) degrade mRNA, with poly (A)-specific ribonuclease (PARN) crucial for eukaryotic mRNA deadenylation.
- PARN plays a key role in mRNA stability and has non-conventional functions.
- Altered RNase activity could impact cancer-associated mRNA stability, potentially varying by cell origin.
Purpose of the Study:
- To investigate the impact of PARN knockdown on cancer-associated gene expression in different cell lineages.
- To examine the effects of PARN depletion on lung cancer cell proliferation and apoptosis.
Main Methods:
- siRNA-mediated knockdown of PARN in lung (NCI-H460, NCI-H522) and kidney (HEK-293) cell lines.
- Quantitative real-time PCR to analyze post-transcriptional expression of oncogenes and tumor suppressor genes.
- Assessment of lung cancer cell proliferation and death following PARN depletion.
Main Results:
- PARN depletion caused cell-specific alterations in oncogene and tumor suppressor gene expression.
- Tumor suppressor genes consistently downregulated across all tested cell types.
- Oncogene expression varied: upregulated in HEK-293 cells but mostly downregulated in lung cancer cells.
- PARN depletion did not affect lung cancer cell proliferation, contradicting prior studies.
Conclusions:
- PARN deficiency distinctly alters cancer-associated mRNA stability based on cell lineage.
- PARN may not serve as a significant cancer biomarker, particularly for lung cancer, despite prior therapeutic suggestions.
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