Abstract 1243: FAM134B mutation in esophageal squamous cell carcinoma: Its clinical significance and quantification by electrochemical methods
Authors: Haque Md. Hakimul , Gopalan Vinod , Shiddiky Muhammad J. A. , Lam Alfred K. 
Published: July 2017

Aim: The aim of this research was to detect novel sites of FAM134B mutations, copy number variations and their clinicopathological significance in esophageal squamous cell carcinoma (ESCC) patients. Also, this study was intended to develop a simple and inexpensive electrochemical detection method for the analysis of FAM134B mutations using a single-use and disposable screen-printed electrode.

Method: Approximately 102 fresh tissue samples of ESCC and matched non-cancer adjacent tissues were recruited. The DNA copy numbers of FAM134B were initially studied by qRT-PCR. The FAM134B mutations were then quantified via high resolution melt curve (HRM) and Sanger sequencing analysis. In order to quantify the level of point mutation or SNPs in FAM134B gene, a new electrochemical method was also developed. The underlying working principle of the method is relied on the base dependent affinity interactions towards gold electrode. Since two DNA sequences with different DNA base compositions (i.e., amplified mutated sequences will be distinctly different than its wild type sequence) will have different adsorption affinity towards an unmodified gold electrode, accurate measurement of adsorbed DNA on the electrode surface will give the measure of point mutation or SNPs present in the DNA sequences. Target DNA sequences were first extracted from clinical samples and then PCR amplified and purified prior to adsorption on a single-use screen-printed gold electrode. The amount of mutation sites on a DNA sequence is quantified by monitoring the Faradaic current generated by the [Fe(CN)6]3-/4- system present in the electrolyte solution.

Result: Amplification of FAM134B DNA was noted in 37% of ESCC tissues whereas 35% cases showed loss of FAM134B copies compared to matched non-tumor tissues. Overall, thirty-seven FAM134B mutations were documented in exons 4, 5, 7, 9 as well as introns 2, 4-8 of FAM134B. Also, FAM134B mutations were detected in all the metastatic ESCC cases and in 14% (8/57) of the primary ESCC. Using the new electrochemical method, we were able to detect mutations in 50 ng of target PCR-amplified product within 1 h with high reproducibility (% RSD= &lt;2) and specificity.

Conclusion: DNA copy number variations and frequent mutations of FAM134B in metastatic lymph node tissues in ESCC patients indicate its critical role in the pathogenesis of ESCCs. Also the mutation detection via electrochemical methods was successful distinguishing single point mutation in DNA from oesophageal cancer implying its potential application in point mutation detection in clinical diagnostics.

Note: This abstract was not presented at the meeting.

Citation Format: Md. Hakimul Haque, Vinod Gopalan, Muhammad J. A. Shiddiky, Alfred K. Lam. FAM134B mutation in esophageal squamous cell carcinoma: Its clinical significance and quantification by electrochemical methods [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1243. doi:10.1158/1538-7445.AM2017-1243