Small nucleolar RNA signatures as biomarkers for non-small-cell lung cancer

Abstract

Background: Non-small-cell lung cancer (NSCLC) is the leading cause of cancer death. Early detection of NSCLC will improve its outcome. The current techniques for NSCLC early detection are either invasive or have low accuracy. Molecular analyses of clinical specimens present promising diagnostic approaches. Non-coding RNAs (ncRNAs) play an important role in tumorigenesis and could be developed as biomarkers for cancer. Here we aimed to develop small nucleolar RNAs (snoRNAs), a common class of ncRNAs, as biomarkers for NSCLC early detection. The study comprised three phases: (1) profiling snoRNA signatures in 22 NSCLC tissues and matched noncancerous lung tissues by GeneChip Array, (2) validating expressions of the signatures by RT-qPCR in the tissues, and (3) evaluating plasma expressions of the snoRNAs in 37 NSCLC patients, 26 patients with chronic obstructive pulmonary disease (COPD), and 22 healthy subjects.

Results: In the surgical tissues, six snoRNAs were identified, which were overexpressed in all tumour tissues compared with their normal counterparts. The overexpressions of the genes in tumors were confirmed by RT-qPCR. The snoRNAs were stably present and reliably detectable in plasma. Of the six genes, three (SNORD33, SNORD66 and SNORD76) displayed higher plasma expressions in NSCLC patients compared with the cancer-free individuals (All < 0.01). The use of the three genes produced 81.1% sensitivity and 95.8% specificity in distinguishing NSCLC patients from both normal and COPD subjects. The plasma snoRNA expressions were not associated with stages and histological types of NSCLC (All > 0.05).

Conclusions: The identified snoRNAs provide potential markers for NSCLC early detection.

Figure 1

SnoRNAs differentially expressed in 22 stage I non-small-cell lung cancer (NSCLC) tissues versus normal lung tissues. Hierarchical clustering of 31 snoRNA genes with a significantly different expression (p < 0.01) in tumour tissues. Rows represent individual genes; columns represent individual tissue samples. The scale stands for the intensity of gene expression (log2 scale ranges between -3.5 and 3.5).

Figure 2

Plasma expression levels of the six snoRNAs in 22 healthy controls, 26 patients with chronic obstructive pulmonary disease (COPD), and 37 patients with non-small-cell lung cancer (NSCLC). Horizontal lines denote mean values. *, statistical significance (< 0.01) of expression levels of snoRNA between NSCLC patients and healthy controls. ^†, statistical significance (< 0.01) of expression levels of snoRNA between COPD patients and healthy controls. ^‡, statistical significance (< 0.01) of expression levels of snoRNA between NSCLC patients and COPD patients.