Altered expression of cell cycle and apoptotic proteins in chronic hepatitis C virus infection

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Altered expression of cell cycle and apoptotic proteins in chronic hepatitis C

virus infection

A disrupted cell cycle progression of hepatocytes was reported in chronic

hepatitis C virus (HCV) infection, which can contribute significantly in the

associated pathogenesis. The present study aimed to further elaborate these

disruptions by evaluating the expression of key cell cycle and apoptotic

proteins in chronic HCV infection with particular reference to genotype 3.

Archival liver biopsy specimens of chronic HCV-infection (n=46) and normal

histology (n=5) were analyzed by immunohistochemistry using antibodies against

proliferation marker Mcm-2, G1 phase marker Cyclin D1, S phase marker Cyclin A,

cell cycle regulators p21 (CDK inhibitor) and p53 (tumor suppressor protein),

apoptotic protein Caspase-3 and anti-apoptotic protein Bcl-2.

Results: Elevated Mcm-2 expression was observed in hepatocytes in chronic HCV

infection, indicating increased cell cycle entry.

Cyclin D1 expression was higher than cyclin A, which suggests a slow progression

through the G1 phase. Expression of cell cycle regulators p21 and p53 was

elevated, with no concordance between their expressions.

The Mcm-2 and p21 expressions were associated with the fibrosis stage (p =

0.0001 and 0.001 respectively) and that of p53 with the inflammation grade (p =

0.051). Apoptotic marker, Caspase-3, was mostly confined to sinusoidal lining

cells with little expression in hepatocytes.

Anti-apoptotic protein, Bcl-2, was negligible in hepatocytes and detected

principally in infiltrating lymphocytes. Expression of all these proteins was

unrelated to the HCV genotype and were detected only rarely in the hepatocytes

of normal liver.

Conclusion: The results showed an arrested cell cycle state in the hepatocytes

of chronic HCV infection, regardless of any association with genotype 3.

Cell cycle arrest is characterized by an increased expression of p21, in

relation to fibrosis, and of p53 in relation to inflammation. Furthermore,

expression of p21 was independent of the p53 expression and coincided with the

reduced expression of apoptotic protein Caspase-3 in hepatocytes.

The altered expression of these cell cycle proteins in hepatocytes is suggestive

of an impaired cell cycle progression that could limit the regenerative response

of the liver to ongoing injury, leading to the progression of disease.

Author: Saira Sarfraz, Saeed Hamid, Anwar Siddiqui, Snawar Hussain, Shahid

Pervez and Graeme

Credits/Source: BMC Microbiology 2008, 8:133

[Guest guest]

http://7thspace.com/headlines/288996/altered_expression_of_cell_cycle_and_apopto\

tic_proteins_in_chronic_hepatitis_c_virus_infection.html

Altered expression of cell cycle and apoptotic proteins in chronic hepatitis C

virus infection

A disrupted cell cycle progression of hepatocytes was reported in chronic

hepatitis C virus (HCV) infection, which can contribute significantly in the

associated pathogenesis. The present study aimed to further elaborate these

disruptions by evaluating the expression of key cell cycle and apoptotic

proteins in chronic HCV infection with particular reference to genotype 3.

Archival liver biopsy specimens of chronic HCV-infection (n=46) and normal

histology (n=5) were analyzed by immunohistochemistry using antibodies against

proliferation marker Mcm-2, G1 phase marker Cyclin D1, S phase marker Cyclin A,

cell cycle regulators p21 (CDK inhibitor) and p53 (tumor suppressor protein),

apoptotic protein Caspase-3 and anti-apoptotic protein Bcl-2.

Results: Elevated Mcm-2 expression was observed in hepatocytes in chronic HCV

infection, indicating increased cell cycle entry.

Cyclin D1 expression was higher than cyclin A, which suggests a slow progression

through the G1 phase. Expression of cell cycle regulators p21 and p53 was

elevated, with no concordance between their expressions.

The Mcm-2 and p21 expressions were associated with the fibrosis stage (p =

0.0001 and 0.001 respectively) and that of p53 with the inflammation grade (p =

0.051). Apoptotic marker, Caspase-3, was mostly confined to sinusoidal lining

cells with little expression in hepatocytes.

Anti-apoptotic protein, Bcl-2, was negligible in hepatocytes and detected

principally in infiltrating lymphocytes. Expression of all these proteins was

unrelated to the HCV genotype and were detected only rarely in the hepatocytes

of normal liver.

Conclusion: The results showed an arrested cell cycle state in the hepatocytes

of chronic HCV infection, regardless of any association with genotype 3.

Cell cycle arrest is characterized by an increased expression of p21, in

relation to fibrosis, and of p53 in relation to inflammation. Furthermore,

expression of p21 was independent of the p53 expression and coincided with the

reduced expression of apoptotic protein Caspase-3 in hepatocytes.

The altered expression of these cell cycle proteins in hepatocytes is suggestive

of an impaired cell cycle progression that could limit the regenerative response

of the liver to ongoing injury, leading to the progression of disease.

Author: Saira Sarfraz, Saeed Hamid, Anwar Siddiqui, Snawar Hussain, Shahid

Pervez and Graeme

Credits/Source: BMC Microbiology 2008, 8:133