Table 2. Function of selected genes.

Gene Name	Expression	Functions	References
HOXA10	Increased	Homebox A10 (HOXA10) is part of the A cluster, on chromosome 7, of the class of transcription factorscalled homebox genes. It encodes a DNA-binding transcription factor that may regulate gene expression, morphogenesis, and differentiation. More specifically, it may function in fertility, embryo viability, and regulation of hematopoietic lineage commitment	[26]
CLCA2	Increased	The protein encoded by Chloride channel accessory 2 (CLCA2) gene, on chromosome 1, belongs to the calcium sensitive chloride conductance protein family. Since this protein is expressed predominantly in trachea and lung, it is suggested to play a role in the complex pathogenesis of cystic fibrosis. It may also serve as adhesion molecule for lung metastatic cancer cells, mediating vascular arrest and colonization, and furthermore, it has beenimplicated to act as a tumor suppressor gene for breast cancer.	[47] [48]
AKR1B10	Increased	Aaldo-keto reductase family 1,member B10 (AKR1B10) gene encodes a member of the aldo/keto reductase superfamily, which consists of more than 40 known enzymes and proteins. It is highly expressed in lung, adrenal gland, small intestine and colonand may play an important role in liver carcinogenesis.	[49]
FABP3	Increased	The intracellular fatty acid-binding proteins (FABPs) belong to a multigene family. FABPs are divided into at least three distinct types, hepatic-, intestinal- and cardiac-type. They participate in the uptake, intracellular metabolism and/or transport of long-chain fatty acids, in the modulation of cell growth and proliferation. FABP3 gene contains four exons and its function is to arrest growth of mammary epithelial cells. This gene is acandidate tumor suppressor gene for human breast cancer.	[50]
SCGB1A1	Decreased	Secretoglobin, family 1A, member 1(SCGB1A1) gene encodes a member of the secretoglobin family of small secreted proteins. The encoded protein has been implicated in numerous functions including anti-inflammation, inhibition of phospholipase A2 and the sequestering of hydrophobic ligands. Defects inthis gene are associated with a susceptibility to asthma	[51]
PSCA	Decreased	Prostate stem cell antigen (PSCA) gene encodes a glycosylphosphatidylinositol-anchored cell membrane glycoprotein. In addition to being highly expressed in the prostate it is also expressed in the bladder, placenta, colon, kidney and stomach. This gene is up-regulated in a large proportion of prostatecancers and is also detected in cancers of the bladder and pancreas. The function of PSCA in tumor biology and the regulatory mechanism of PSCA expression still remains unknown.	[30]
PGC	Decreased	Progastricsin (pepsinogen C) (PGC) gene encodes an aspartic proteinase that belongs to the peptidase family A1. The encoded protein is a digestive enzyme that is produced inthe stomach and constitutes a major component of the gastric mucosa. This protein is also secreted into the serum. This protein is synthesized as an inactive zymogen converted into its active mature format low Ph.	[52]
PRSS1	Decreased	Protease, serine, 1 (trypsin 1) (PRSS1) gene encodes a trypsinogen, which is a member of the trypsin family of serine proteases. This enzyme is secreted by the pancreas and cleaved to its active form in the small intestine. This gene and severalother trypsinogen genes are localized to the T cell receptor beta locuson chromosome 7.	[53]
TFF1	Decreased	Trefoil factor 1 (TFF1) gene is a members of the trefoil family. They are stable secretory proteins expressed in gastrointestinal mucosa. Their functions are not defined, but they may protect the mucosa from insults, stabilize the mucus layer,and affect healing of the epithelium. This gene, which is expressed in the gastric mucosa, has also been studied because of its expression in human tumors. This gene and two other related trefoil family member genes are found in a cluster on chromosome 21.	[54]
SPRR1B	Decreased	Small proline-rich proteins (SPRRs) multi-gene family maps on chromosome 1. Their expression is highin epithelia of oral tissues such as tongue, esophagus and stomach, in contrast to external dry epithelia, such as skin. It has a role during squamous differentiation of skin and respiratory epithelial cells. Moreover, SPRR1 is expressed in squamous tumors of the lung. However, its role in non-squamous cells is largely unknown; it seems that it alsooccurs in non-squamous tissues and cell lines. This protein family is an important component of the cornified cell envelope, a structure formed beneath the plasma membrane of squamous differentiated cells by extensive cross-linking of several proteins.	[55], [56], [57]