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The human immunodeficiency virus type 1 Vpr protein and its carboxy-terminally truncated form induce apoptosis in tumor cells.

Nonaka M, Hashimoto Y, Takeshima SN, Aida Y - Cancer Cell Int. (2009)

Bottom Line: We have reported previously that C81, a carboxy-terminally truncated form of Vpr, interferes with cell proliferation and results in apoptosis without G2 arrest.In contrast, Vpr resulted in G2 arrest and apoptosis in HeLa and 293 T cells.Overall, Vpr and C81 have potential as novel therapeutic agents for treatment of cancer.

View Article: PubMed Central - HTML - PubMed

Affiliation: Viral Infectious Diseases Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. mizuho-624.1128@s7.dion.ne.jp

ABSTRACT
The human immunodeficiency virus type 1 (HIV-1) accessory protein Vpr induces apoptosis after cell cycle arrest at the G2 phase in primate cells. We have reported previously that C81, a carboxy-terminally truncated form of Vpr, interferes with cell proliferation and results in apoptosis without G2 arrest. Here, we investigated whether this property of Vpr and C81 could be exploited for use as a potential anticancer agent. First, we demonstrated that C81 induced G1 arrest and apoptosis in all tumor cells tested. In contrast, Vpr resulted in G2 arrest and apoptosis in HeLa and 293 T cells. Vpr also suppressed the damaged-DNA-specific binding protein 1 (DDB1) in HepG2 cells, thereby inducing apoptosis without G2 arrest. G2 arrest was restored when DDB1 was overexpressed in cells that also expressed Vpr. Surprisingly, C81 induced G2 arrest when DDB1 was overexpressed in HepG2 cells, but not in HeLa or 293 T cells. Thus, the induction of Vpr- and C81-mediated cell cycle arrest appears to depend on the cell type, whereas apoptosis was observed in all tumor cells tested. Overall, Vpr and C81 have potential as novel therapeutic agents for treatment of cancer.

No MeSH data available.


Related in: MedlinePlus

Construction and expression of Vpr and C81. (A) Plasmids containing cDNA for Vpr and C81 were generated from HIV-1NL4-3. Schematic presentation of the predicted first α-helical domain (αH1), second α-helical domain (αH2), third α-helical domain (αH3) and the arginine rich region of Vpr are indicated. (B) Western blotting of wild-type Vpr and C81. HeLa, HepG2, and 293 T cells were transfected with pME18Neo encoding Flag-tagged wild-type Vpr or C81, or the empty vector control pME18Neo-Flag, together with pSV-β-galactosidase. Transfected cells were collected and lysed 48 h after transfection. Lysates with equal β-galactosidase activity were subjected to Western blot analysis using anti-Flag.
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Figure 1: Construction and expression of Vpr and C81. (A) Plasmids containing cDNA for Vpr and C81 were generated from HIV-1NL4-3. Schematic presentation of the predicted first α-helical domain (αH1), second α-helical domain (αH2), third α-helical domain (αH3) and the arginine rich region of Vpr are indicated. (B) Western blotting of wild-type Vpr and C81. HeLa, HepG2, and 293 T cells were transfected with pME18Neo encoding Flag-tagged wild-type Vpr or C81, or the empty vector control pME18Neo-Flag, together with pSV-β-galactosidase. Transfected cells were collected and lysed 48 h after transfection. Lysates with equal β-galactosidase activity were subjected to Western blot analysis using anti-Flag.

Mentions: Vpr has previously been demonstrated to induce G2 cell cycle arrest as well as apoptosis in a number of tumor cells [29,30]. Previously, we found that C81, a carboxy-terminally truncated form of Vpr, is a strong inducer of apoptosis with G1 arrest, but not G2 arrest, of the cell cycle, and that the apoptotic activity of C81 is stronger than that of Vpr in human cells [35]. Based on the growth arresting and apoptosis inducing properties in tumor cells, C81 and Vpr have potential therapeutic applications for treating cancer. To further investigate this potential, we examined whether Vpr and C81 can induce apoptosis in tumor cells. We transiently transfected two human tumor cell lines, HeLa and HepG2, as well as 293 T cells, with a pME18Neo expression vector encoding Flag-tagged wild-type Vpr, C81, or the empty vector pME18Neo-Flag as a control. We examined the expression of Vpr and C81, 48 h post-transfection by Western blot analysis using the anti-Flag M2 monoclonal antibody. Fig. 1 shows protein bands with molecular masses that are consistent with the calculated masses of the sequences of Flag-tagged Vpr and Flag-tagged C81.


The human immunodeficiency virus type 1 Vpr protein and its carboxy-terminally truncated form induce apoptosis in tumor cells.

Nonaka M, Hashimoto Y, Takeshima SN, Aida Y - Cancer Cell Int. (2009)

Construction and expression of Vpr and C81. (A) Plasmids containing cDNA for Vpr and C81 were generated from HIV-1NL4-3. Schematic presentation of the predicted first α-helical domain (αH1), second α-helical domain (αH2), third α-helical domain (αH3) and the arginine rich region of Vpr are indicated. (B) Western blotting of wild-type Vpr and C81. HeLa, HepG2, and 293 T cells were transfected with pME18Neo encoding Flag-tagged wild-type Vpr or C81, or the empty vector control pME18Neo-Flag, together with pSV-β-galactosidase. Transfected cells were collected and lysed 48 h after transfection. Lysates with equal β-galactosidase activity were subjected to Western blot analysis using anti-Flag.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2735735&req=5

Figure 1: Construction and expression of Vpr and C81. (A) Plasmids containing cDNA for Vpr and C81 were generated from HIV-1NL4-3. Schematic presentation of the predicted first α-helical domain (αH1), second α-helical domain (αH2), third α-helical domain (αH3) and the arginine rich region of Vpr are indicated. (B) Western blotting of wild-type Vpr and C81. HeLa, HepG2, and 293 T cells were transfected with pME18Neo encoding Flag-tagged wild-type Vpr or C81, or the empty vector control pME18Neo-Flag, together with pSV-β-galactosidase. Transfected cells were collected and lysed 48 h after transfection. Lysates with equal β-galactosidase activity were subjected to Western blot analysis using anti-Flag.
Mentions: Vpr has previously been demonstrated to induce G2 cell cycle arrest as well as apoptosis in a number of tumor cells [29,30]. Previously, we found that C81, a carboxy-terminally truncated form of Vpr, is a strong inducer of apoptosis with G1 arrest, but not G2 arrest, of the cell cycle, and that the apoptotic activity of C81 is stronger than that of Vpr in human cells [35]. Based on the growth arresting and apoptosis inducing properties in tumor cells, C81 and Vpr have potential therapeutic applications for treating cancer. To further investigate this potential, we examined whether Vpr and C81 can induce apoptosis in tumor cells. We transiently transfected two human tumor cell lines, HeLa and HepG2, as well as 293 T cells, with a pME18Neo expression vector encoding Flag-tagged wild-type Vpr, C81, or the empty vector pME18Neo-Flag as a control. We examined the expression of Vpr and C81, 48 h post-transfection by Western blot analysis using the anti-Flag M2 monoclonal antibody. Fig. 1 shows protein bands with molecular masses that are consistent with the calculated masses of the sequences of Flag-tagged Vpr and Flag-tagged C81.

Bottom Line: We have reported previously that C81, a carboxy-terminally truncated form of Vpr, interferes with cell proliferation and results in apoptosis without G2 arrest.In contrast, Vpr resulted in G2 arrest and apoptosis in HeLa and 293 T cells.Overall, Vpr and C81 have potential as novel therapeutic agents for treatment of cancer.

View Article: PubMed Central - HTML - PubMed

Affiliation: Viral Infectious Diseases Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. mizuho-624.1128@s7.dion.ne.jp

ABSTRACT
The human immunodeficiency virus type 1 (HIV-1) accessory protein Vpr induces apoptosis after cell cycle arrest at the G2 phase in primate cells. We have reported previously that C81, a carboxy-terminally truncated form of Vpr, interferes with cell proliferation and results in apoptosis without G2 arrest. Here, we investigated whether this property of Vpr and C81 could be exploited for use as a potential anticancer agent. First, we demonstrated that C81 induced G1 arrest and apoptosis in all tumor cells tested. In contrast, Vpr resulted in G2 arrest and apoptosis in HeLa and 293 T cells. Vpr also suppressed the damaged-DNA-specific binding protein 1 (DDB1) in HepG2 cells, thereby inducing apoptosis without G2 arrest. G2 arrest was restored when DDB1 was overexpressed in cells that also expressed Vpr. Surprisingly, C81 induced G2 arrest when DDB1 was overexpressed in HepG2 cells, but not in HeLa or 293 T cells. Thus, the induction of Vpr- and C81-mediated cell cycle arrest appears to depend on the cell type, whereas apoptosis was observed in all tumor cells tested. Overall, Vpr and C81 have potential as novel therapeutic agents for treatment of cancer.

No MeSH data available.


Related in: MedlinePlus