Chapter 2 - University of British Columbia
Chapter 2 - University of British Columbia
Chapter 2 - University of British Columbia
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
expressed in response to smoke exposure and found a subset <strong>of</strong> genes that were reversible<br />
upon smoking cessation and another subset <strong>of</strong> genes irreversible upon smoking cessation [35].<br />
Those genes which were irreversibly altered after heavy smoke exposure may have implications<br />
in affecting future risk <strong>of</strong> developing lung cancer. Moreover, these findings also suggest that<br />
when trying to identify cancer-specific changes when unmatched control samples are not<br />
available, clinical characteristics such as smoking status should be taken into consideration<br />
when comparisons are made.<br />
1.12.3 Differential gene expression analysis in lung cancer<br />
With the non-malignant, baseline gene expression defined, differential gene expression in early<br />
stages <strong>of</strong> lung cancer and locally invasive squamous cell carcinoma were then assessed [101].<br />
It was found that genes associated with epidermal development were increased in expression<br />
and mucociliary function were decreased in expression in carcinoma-in-situ as well as in<br />
precancerous stages. Finally, genes associated with tissue re-modelling were also altered in<br />
expression in local invasive cancer and also showed altered expression in carcinoma-in-situ,<br />
suggesting this function is affected early in cancer development.<br />
The Wnt pathway has been shown to be aberrant in many cancer types. At the time the study<br />
began, there were two branches <strong>of</strong> the pathway that were known to exist, canonical and non-<br />
canonical, whose activation resulted in different downstream consequences. While the<br />
canonical branch was the primary focus <strong>of</strong> most researchers studying this pathway, we sought<br />
to assess the role <strong>of</strong> the non-canonical branch in lung squamous cell carcinoma using semi-<br />
quantitative and quantitative PCR <strong>of</strong> genes which were a part <strong>of</strong> the non-canonical branch [102].<br />
From this study, it was found that (i) these non-canonical genes were expressed in the normal<br />
lung and (ii) some <strong>of</strong> these non-canonical genes were differentially expressed in tumors.<br />
An important consideration in the analysis <strong>of</strong> differential gene expression in cancer is the use <strong>of</strong><br />
suitable reference genes for data normalization. This consideration is critical to both<br />
15