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Page 6 of 10 Farghaly et al. Hepatoma Res 2018;4:41 I http://dx.doi.org/10.20517/2394-5079.2018.30

A

B

Figure 2. Heat shock (HS) reduces HCV-NS5A gene expression profile. (A) Relative gene expression of HCV-NS5A in HepG2 cells
that were stressed with HS for 5 min in comparison with non-treated and infected cells (control-infection); (B) the expression of NS5A
corresponding protein in HS treated cells (HS-infection) compared to control-infected cells indicated by Flowcytometry. Error bars
indicate standard deviation of two independent experiments

L22 ribosomal protein is regulated by HS stress condition
To assess the inhibitory effect of HS on RPL22 protein, the protein profile of RPL22 has been detected
in HepG2 cells that were infected with HCV and subjected to 5 min HS using flowcytometry. The result
showed that approximately 25% of total HepG2 cells were positively expressed RPL22 in response to HS
treatment, while 40% of total cells were positive to RPL22 in control-infected cells [Figure 4]. These findings
indicate that few minutes of HS stress lead to obvious depletion of RPL22 in HepG2 cells. Together, our data
demonstrate that HS treatment is an environmental stress leading to accumulation of Alu-RNA element that
post-transitionally regulates RPL22 and subsequently disturbs HCV replication in HepG2 cells.

DISCUSSION
Our findings provide a new therapeutic strategy against HCV infection without detectable toxic effect on
cell viability. Treatment with HS (45 ºC for 5 min) is able to decease virus replication indicated by viral NS5A
expression at RNA and protein levels. This interruption in viral replication may be due to up-regulation
of Alu repeats element as a response to HS. Alu molecule is non-coding RNA that is present at elevated
levels in stress condition. Consequently, Alu repeats are increasingly being associated with the physiological
stress response . Alu sequences are the most abundant short interspersed repeated elements in the human
[19]
genome. The accumulation of Alu-RNA molecules has been observed in variety of cancer cells in association
with cellular microRNA . However, the exact molecular function of Alu-RNA element is still not completely
[33]