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Loss of IRF8 Inhibits the Growth of Diffuse Large B-cell Lymphoma.

Xu Y, Jiang L, Fang J, Fang R, Morse HC, Ouyang G, Zhou JX - J Cancer (2015)

Bottom Line: In this study, using shRNA-mediated knockdown of IRF8 expression, we found that the loss of IRF8 significantly reduced the proliferation of DLBCL cells (P<0.05).Mechanistically, decreasing the levels of IRF8 led to a suppression of the phosphorylation of p38 and ERK, molecules critical for B cell proliferation.Furthermore, using a xenograft lymphoma mouse model, we found that the loss of IRF8 significantly inhibited the growth of lymphomas in vivo (P<0.05).

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Pathology, Ningbo University School of Medicine, Ningbo, Zhejiang, China.

ABSTRACT
IRF8 is a transcription factor with a critical role in B lymphocyte development and functions. Its role in human diffuse large B-cell lymphoma (DLBCL), however, remained elusive. In this study, using shRNA-mediated knockdown of IRF8 expression, we found that the loss of IRF8 significantly reduced the proliferation of DLBCL cells (P<0.05). Mechanistically, decreasing the levels of IRF8 led to a suppression of the phosphorylation of p38 and ERK, molecules critical for B cell proliferation. Furthermore, using a xenograft lymphoma mouse model, we found that the loss of IRF8 significantly inhibited the growth of lymphomas in vivo (P<0.05). Immunohistochemical analysis of human DLBCL tissues revealed that the levels of IRF8 were significantly greater in non-germinal center B-cell-like (non-GCB) subtype than that in GCB subtype (P<0.05). Analysis of public available data also suggested that the expression levels of IRF8 mRNA in human DLBCL tissues were inversely correlated with patients' overall survival time. Taken together, this study suggested that IRF8 may play an oncogenic role in human DLBCL by promoting cell proliferation.

No MeSH data available.


Related in: MedlinePlus

The decreased levels of IRF8 in DLBCL cells treated with shRNAs specific for IRF8. Two shRNA clones (shRNA-1 and shRNA-2) were used in the study based on their efficiencies of knocking down the levels of IRF8 in OCI-Ly01 and OCI-Ly10 cells. The levels of both IRF8 proteins (A) and transcripts (B) decreased in specific shRNA-treated DLBCL cells. * depicts statistically significant difference between the IRF8 knockdown cells and control cells in transcripts (P<0.05).
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Figure 1: The decreased levels of IRF8 in DLBCL cells treated with shRNAs specific for IRF8. Two shRNA clones (shRNA-1 and shRNA-2) were used in the study based on their efficiencies of knocking down the levels of IRF8 in OCI-Ly01 and OCI-Ly10 cells. The levels of both IRF8 proteins (A) and transcripts (B) decreased in specific shRNA-treated DLBCL cells. * depicts statistically significant difference between the IRF8 knockdown cells and control cells in transcripts (P<0.05).

Mentions: To detect the function of IRF8 in DLBCL, we used lentiviral-mediated shRNA to knock down the levels of IRF8 in DLBCL cells. Two shRNA constructs (shRNA-1 and shRNA-2) were chosen based on their effectiveness in decreasing the levels of IRF8. The results showed that both shRNA constructs decreased the levels of IRF8 mRNA and protein significantly in OCI-Ly01 and OCI-Ly10 cells (P<0.05) (Figure 1). Subsequently, we examined the effect of decreasing levels of IRF8 on DLBCL cells proliferation. Comparing to the control cells, the decrease in levels of IRF8 significantly suppressed the proliferation of DLBCL cells (Figure 2). We further asked if cell cycle arrest attributed to the suppression of proliferation. To our surprise, loss of IRF8 did not change cell cycle distribution (Figure S1). To explore the possible mechanisms responsible for the suppression of cell proliferation induced by IRF8 knockdown, we used fluorescent dye CFSE to label the cells and analyzed the rate of cell division. The fluorescence intensity was partitioned equally among daughter cells during each division. The results showed that the cell division was reduced in OCI-Ly01 and OCI-Ly10 cells with IRF8 knockdown comparing to the control cells (Figure 3).


Loss of IRF8 Inhibits the Growth of Diffuse Large B-cell Lymphoma.

Xu Y, Jiang L, Fang J, Fang R, Morse HC, Ouyang G, Zhou JX - J Cancer (2015)

The decreased levels of IRF8 in DLBCL cells treated with shRNAs specific for IRF8. Two shRNA clones (shRNA-1 and shRNA-2) were used in the study based on their efficiencies of knocking down the levels of IRF8 in OCI-Ly01 and OCI-Ly10 cells. The levels of both IRF8 proteins (A) and transcripts (B) decreased in specific shRNA-treated DLBCL cells. * depicts statistically significant difference between the IRF8 knockdown cells and control cells in transcripts (P<0.05).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4543755&req=5

Figure 1: The decreased levels of IRF8 in DLBCL cells treated with shRNAs specific for IRF8. Two shRNA clones (shRNA-1 and shRNA-2) were used in the study based on their efficiencies of knocking down the levels of IRF8 in OCI-Ly01 and OCI-Ly10 cells. The levels of both IRF8 proteins (A) and transcripts (B) decreased in specific shRNA-treated DLBCL cells. * depicts statistically significant difference between the IRF8 knockdown cells and control cells in transcripts (P<0.05).
Mentions: To detect the function of IRF8 in DLBCL, we used lentiviral-mediated shRNA to knock down the levels of IRF8 in DLBCL cells. Two shRNA constructs (shRNA-1 and shRNA-2) were chosen based on their effectiveness in decreasing the levels of IRF8. The results showed that both shRNA constructs decreased the levels of IRF8 mRNA and protein significantly in OCI-Ly01 and OCI-Ly10 cells (P<0.05) (Figure 1). Subsequently, we examined the effect of decreasing levels of IRF8 on DLBCL cells proliferation. Comparing to the control cells, the decrease in levels of IRF8 significantly suppressed the proliferation of DLBCL cells (Figure 2). We further asked if cell cycle arrest attributed to the suppression of proliferation. To our surprise, loss of IRF8 did not change cell cycle distribution (Figure S1). To explore the possible mechanisms responsible for the suppression of cell proliferation induced by IRF8 knockdown, we used fluorescent dye CFSE to label the cells and analyzed the rate of cell division. The fluorescence intensity was partitioned equally among daughter cells during each division. The results showed that the cell division was reduced in OCI-Ly01 and OCI-Ly10 cells with IRF8 knockdown comparing to the control cells (Figure 3).

Bottom Line: In this study, using shRNA-mediated knockdown of IRF8 expression, we found that the loss of IRF8 significantly reduced the proliferation of DLBCL cells (P<0.05).Mechanistically, decreasing the levels of IRF8 led to a suppression of the phosphorylation of p38 and ERK, molecules critical for B cell proliferation.Furthermore, using a xenograft lymphoma mouse model, we found that the loss of IRF8 significantly inhibited the growth of lymphomas in vivo (P<0.05).

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Pathology, Ningbo University School of Medicine, Ningbo, Zhejiang, China.

ABSTRACT
IRF8 is a transcription factor with a critical role in B lymphocyte development and functions. Its role in human diffuse large B-cell lymphoma (DLBCL), however, remained elusive. In this study, using shRNA-mediated knockdown of IRF8 expression, we found that the loss of IRF8 significantly reduced the proliferation of DLBCL cells (P<0.05). Mechanistically, decreasing the levels of IRF8 led to a suppression of the phosphorylation of p38 and ERK, molecules critical for B cell proliferation. Furthermore, using a xenograft lymphoma mouse model, we found that the loss of IRF8 significantly inhibited the growth of lymphomas in vivo (P<0.05). Immunohistochemical analysis of human DLBCL tissues revealed that the levels of IRF8 were significantly greater in non-germinal center B-cell-like (non-GCB) subtype than that in GCB subtype (P<0.05). Analysis of public available data also suggested that the expression levels of IRF8 mRNA in human DLBCL tissues were inversely correlated with patients' overall survival time. Taken together, this study suggested that IRF8 may play an oncogenic role in human DLBCL by promoting cell proliferation.

No MeSH data available.


Related in: MedlinePlus