Abstract 1928: Characterization of the RPL9 and LIAS genes in lung tumors.
Authors: Dlamini Zodwa , Mbita Zukile , Mphahlele Lebogang 
Published: August 2014

RPL9 is located on chromosome 4p14 and is approximately 5.5 kb in length and contains 8 exons. The message for human RPL9 is 712 nucleotides long. Some of the functions of RPL9 documented this far include the crucial involvement of the gene product in cell proliferation and protein biosynthesis. Lipoic acid synthetase (LIAS) is a 1.73 kb gene located at chromosome 4p14. Alternative splicing occurs at this locus and two transcript variants encoding distinct isoforms have been identified. The protein encoded by LIAS gene belongs to the biotin and lipoic acid synthetases family and localizes in the mitochondrion.

The main objective of this study was to evaluate the expression pattern of RPL9 and LIAS in lung cancer and to characterise their role in apoptosis and also to determine if the expression pattern of this genes varies between normal and diseased state of the tissue.

In Situ hybridization, quantitative Real Time PCR, TUNEL and Bio-informatics have been employed in order to attain the objectives of this study.

In Situ hybridization showed that RPL9 localises in the cytoplasm and it is up-regulated in lung cancer relative to normal lung. LIAS localises in the cytoplasm and it is also up-regulated in lung cancer. The expression of RPL9 was relatively higher than that of LIAS determined by the intensity of localisation. Quantitative real time PCR confirmed the up-regulation of RPL9 and LIAS in lung cancer. RPL9 and LIAS were found to be up-regulated 8 and 4 fold respectively in lung A549 lung adenocarcinoma relative to MRC5 normal lung fibroblast cell lines. TUNEL showed the highest DNA fragmentation in adenocarcinoma, followed by squamous cell lung carcinoma then large cell lung carcinoma which is the same pattern observed in RPL9 and LIAS mRNA localisation by In Situ hybridization.

To further characterise the role of RPL9 and LIAS in human, Bio-informatics tools were used and the results revealed that RPL9 is highly conserved through evolution, up-to 100 % identical to chimpanzee and 98 % to mouse. LIAS was found to be 91 % identical to rat and 90 % identical to mouse.

All these discoveries coupled with resistance to apoptosis of CHO cell line in which RPL9 and LIAS were found to be mutated following promoter-trap mutagenesis, strongly suggests that RPL9 might be playing a role in cell cycle and apoptosis. RPL9 has been highly conserved through evolution. Manipulation of this gene can lead to greater biological discoveries in cancer research and the elevated expression of RPL9 can be used as a molecular marker for early detection of cancer

Citation Format: Zodwa Dlamini, Zukile Mbita, Lebogang Mphahlele. Characterization of the RPL9 and LIAS genes in lung tumors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1928. doi:10.1158/1538-7445.AM2013-1928

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.