## 4 Results and Discussion
### Signal Profiles and P-Values of Extracted Key Genes  
The gene signal profiles of top ranked key genes retrieved using each feature selection method are shown in Figures 4-7. Each gene signal is plotted in HCV-infected and disinfected samples and its P-value is attached along with its Affy ID. The signal profile illustrates the up/downregulated genes. Each figure represents the plot of the gene expression value in the disinfected and infected samples. The x axis represents the samples, 12 samples for the disinfected samples and 12 for the infected one. The Y axis represents the gene expression value. Figure 4: The gene signal profile of top ranked key genes retrieved using \(T\)-test and F-test. Figure 5: The gene signal profiles of top ranked key genes retrieved using Cosine and Pearson’s correlation. Discussing the Relevance of Extracted Key Genes Based on Their Biological Examination and Signal Profiles  
The significance of those genes listed above, and their contributions in cellular functions and malignancies that may happen as risky outcomes of HCV, are discussed here in this section. An identical list was retrieved using \(T\)-test and F-test. It can be inferred that there is a major distinction between the two means of normal and infected samples. Additionally, the whole values of gene expression in infected samples are considerably completely different than the mean of gene expression value in disinfected samples. This is often a validation of the importance of the retrieved genes as key genes for the risky outcomes of HCV. TXNIP, a Thioredoxin interacting protein, has been detected as a downregulated gene, as shown in Figure 4, in all periods of post-infection (12, 18, 24, and 48 h) using \(T\)-test and F-test. TXNIP is known as a vitamin D3 protein and convoluted in a varied range of cellular developments, as well as apoptosis, proliferation, lipid and glucose metabolism, and may  
Figure 6: The gene signal profiles of top ranked key genes retrieved using Euclidean distance. Figure 7: The gene signal profiles of top ranked key genes retrieved using PCA. Additionally be concerned within the metastasis of a range of tumors [36]. Stanniocalcin 2 (STC2) has been detected as a downregulated gene in three periods of post-infection. The encoded protein of STC2 is significant in the regulation of renal and intestinal calcium. Variations in the expression of STC2 may contribute to the appearance of breast cancers, Colorectal cancer, and HCC, as discussed in [37]. Asparagine synthetase(ASNS) and DNA-damaged inducible transcript 4 (DDIT4) have been detected as downregulated in all studied periods of post-infection with HCV. The ASNS gene is extremely regulated in stress, liver development, and HepG2 human hepatocellular carcinoma [38]. DDIT4 has been detected as a downregulated gene, and it encodes a protein that is well known as a biomarker for the prognosis of different types of cancer including liver cancer [39]. In addition, DDIT4 is associated with the TP53 pathway, which is a significant pathway for HCC according to the biological literature [39]. INHBE, inhibin subunit beta E, is detected as a downregulated gene after 24, and 48 h of post-infection. This gene is regulated in cell proliferation, immune response, apoptosis, and hormone secretion [40]. Cystathionine gamma-lyase, CTH, has been detected as downregulated. CTH encodes an enzyme in the cellular processes of liver and kidney and it is a prognostic biomarker for bladder cancer [41]. CHAC1 has only been detected in the first and second periods of post-infection. CHAC1 encodes a protein in the ATF4 signaling. However, these genes are recommended as novel key genes in the replication cycle of HCV, as they have not been addressed before in the literature for HCV, liver cirrhosis, and HCC. COL1A1 has been detected as upregulated after 12 h of post-infection. COL1A1 has been reported recently as a highly up-regulated biomarker in HCC cancer tissues.