Limits...
AF1q: a novel mediator of basal and 4-HPR-induced apoptosis in ovarian cancer cells.

Tiberio P, Cavadini E, Callari M, Daidone MG, Appierto V - PLoS ONE (2012)

Bottom Line: Through gene silencing, AF1q was found functionally involved in 4-HPR-induced apoptosis in A2780, an ovarian cancer cell line highly sensitive to retinoid growth inhibitory and apoptotic effects.Inhibition of the signaling intermediates of the 4-HPR apoptotic cascade showed that AF1q upregulation was depended on prior generation of ROS, induction of ER stress response, JNK activation, and PLAB upmodulation.The study expands the knowledge of the 4-HPR mechanism of action, which has not yet been completely elucidated, identifying AF1q as a novel mediator of retinoid anticancer activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy. paola.tiberio@istitutotumori.mi.it

ABSTRACT

Background: Fenretinide (4-HPR) is a synthetic retinoid that exhibits potent antitumor and chemopreventive activities against different malignancies, including ovarian tumors. We previously showed that in ovarian cancer cells, 4-HPR induces apoptosis through a signaling cascade starting from reactive oxygen species (ROS) generation and involving endoplasmic reticulum (ER) stress response, Jun N-terminal Kinase (JNK) activation, and induction of the proapoptotic PLAcental Bone morphogenetic protein (PLAB). Since recent studies have shown that the oncogene ALL1-fused from chromosome 1q (AF1q), a retinoic acid target gene, is implicated in apoptosis induction by several therapeutic agents, we investigated its possible involvement in the apoptosis induced by 4-HPR in ovarian cancer cells.

Methodology/principal findings: Protein expression analysis, performed in ovarian cancer cells and extended to other histotypes (breast, neuroblastoma, and cervical), revealed that 4-HPR enhanced AF1q expression in cancer cells sensitive to the retinoid but not in resistant cells. Through gene silencing, AF1q was found functionally involved in 4-HPR-induced apoptosis in A2780, an ovarian cancer cell line highly sensitive to retinoid growth inhibitory and apoptotic effects. Inhibition of the signaling intermediates of the 4-HPR apoptotic cascade showed that AF1q upregulation was depended on prior generation of ROS, induction of ER stress response, JNK activation, and PLAB upmodulation. Finally, we found that direct overexpression of AF1q, in the absence of external stimuli, increased apoptosis in ovarian cancer cell lines.

Conclusions/significance: The study expands the knowledge of the 4-HPR mechanism of action, which has not yet been completely elucidated, identifying AF1q as a novel mediator of retinoid anticancer activity. In addition, we demonstrate, for the first time, that AF1q plays a role in the onset of basal apoptosis in ovarian cancer cells, thus providing new information about the activity of this protein whose biologic functions are mostly unknown.

Show MeSH

Related in: MedlinePlus

Effects of 4-HPR on AF1q expression in A2780 and A2780/HPR cells.Western blot analysis for AF1q expression in A2780 (A) and A2780/HPR (B) cells treated for 24 hours with 5 and 10 µM 4-HPR. As a control for loading, the blots were incubated with actin antibody.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3383705&req=5

pone-0039968-g001: Effects of 4-HPR on AF1q expression in A2780 and A2780/HPR cells.Western blot analysis for AF1q expression in A2780 (A) and A2780/HPR (B) cells treated for 24 hours with 5 and 10 µM 4-HPR. As a control for loading, the blots were incubated with actin antibody.

Mentions: Since AF1q was shown to play a role in the apoptosis induced by several therapeutic agents and to be regulated by RA [14], [24], [25], we sought to investigate the potential contribution of the protein in the apoptotic activity of the synthetic retinoid 4-HPR. We analyzed the effect of 4-HPR treatment on AF1q expression in the human ovarian cancer cell line A2780, which is highly sensitive to the antiproliferative and apoptotic effects of the retinoid [26], [27], and in its counterpart A2780/HPR, which has induced resistance to 4-HPR [28]. Protein expression analysis showed that A2780 cells constitutively expressed AF1q protein and that treatment with 5 and 10 µM 4-HPR for 24 hours increased its expression in a dose-dependent manner (Figure 1A). In contrast, 4-HPR treatment did not cause any increase in AF1q protein expression in A2780/HPR cells, even though the cells constitutively expressed it (Figure 1B). Such data suggested an association between AF1q induction by 4-HPR treatment and cell sensitivity to the retinoid.


AF1q: a novel mediator of basal and 4-HPR-induced apoptosis in ovarian cancer cells.

Tiberio P, Cavadini E, Callari M, Daidone MG, Appierto V - PLoS ONE (2012)

Effects of 4-HPR on AF1q expression in A2780 and A2780/HPR cells.Western blot analysis for AF1q expression in A2780 (A) and A2780/HPR (B) cells treated for 24 hours with 5 and 10 µM 4-HPR. As a control for loading, the blots were incubated with actin antibody.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3383705&req=5

pone-0039968-g001: Effects of 4-HPR on AF1q expression in A2780 and A2780/HPR cells.Western blot analysis for AF1q expression in A2780 (A) and A2780/HPR (B) cells treated for 24 hours with 5 and 10 µM 4-HPR. As a control for loading, the blots were incubated with actin antibody.
Mentions: Since AF1q was shown to play a role in the apoptosis induced by several therapeutic agents and to be regulated by RA [14], [24], [25], we sought to investigate the potential contribution of the protein in the apoptotic activity of the synthetic retinoid 4-HPR. We analyzed the effect of 4-HPR treatment on AF1q expression in the human ovarian cancer cell line A2780, which is highly sensitive to the antiproliferative and apoptotic effects of the retinoid [26], [27], and in its counterpart A2780/HPR, which has induced resistance to 4-HPR [28]. Protein expression analysis showed that A2780 cells constitutively expressed AF1q protein and that treatment with 5 and 10 µM 4-HPR for 24 hours increased its expression in a dose-dependent manner (Figure 1A). In contrast, 4-HPR treatment did not cause any increase in AF1q protein expression in A2780/HPR cells, even though the cells constitutively expressed it (Figure 1B). Such data suggested an association between AF1q induction by 4-HPR treatment and cell sensitivity to the retinoid.

Bottom Line: Through gene silencing, AF1q was found functionally involved in 4-HPR-induced apoptosis in A2780, an ovarian cancer cell line highly sensitive to retinoid growth inhibitory and apoptotic effects.Inhibition of the signaling intermediates of the 4-HPR apoptotic cascade showed that AF1q upregulation was depended on prior generation of ROS, induction of ER stress response, JNK activation, and PLAB upmodulation.The study expands the knowledge of the 4-HPR mechanism of action, which has not yet been completely elucidated, identifying AF1q as a novel mediator of retinoid anticancer activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy. paola.tiberio@istitutotumori.mi.it

ABSTRACT

Background: Fenretinide (4-HPR) is a synthetic retinoid that exhibits potent antitumor and chemopreventive activities against different malignancies, including ovarian tumors. We previously showed that in ovarian cancer cells, 4-HPR induces apoptosis through a signaling cascade starting from reactive oxygen species (ROS) generation and involving endoplasmic reticulum (ER) stress response, Jun N-terminal Kinase (JNK) activation, and induction of the proapoptotic PLAcental Bone morphogenetic protein (PLAB). Since recent studies have shown that the oncogene ALL1-fused from chromosome 1q (AF1q), a retinoic acid target gene, is implicated in apoptosis induction by several therapeutic agents, we investigated its possible involvement in the apoptosis induced by 4-HPR in ovarian cancer cells.

Methodology/principal findings: Protein expression analysis, performed in ovarian cancer cells and extended to other histotypes (breast, neuroblastoma, and cervical), revealed that 4-HPR enhanced AF1q expression in cancer cells sensitive to the retinoid but not in resistant cells. Through gene silencing, AF1q was found functionally involved in 4-HPR-induced apoptosis in A2780, an ovarian cancer cell line highly sensitive to retinoid growth inhibitory and apoptotic effects. Inhibition of the signaling intermediates of the 4-HPR apoptotic cascade showed that AF1q upregulation was depended on prior generation of ROS, induction of ER stress response, JNK activation, and PLAB upmodulation. Finally, we found that direct overexpression of AF1q, in the absence of external stimuli, increased apoptosis in ovarian cancer cell lines.

Conclusions/significance: The study expands the knowledge of the 4-HPR mechanism of action, which has not yet been completely elucidated, identifying AF1q as a novel mediator of retinoid anticancer activity. In addition, we demonstrate, for the first time, that AF1q plays a role in the onset of basal apoptosis in ovarian cancer cells, thus providing new information about the activity of this protein whose biologic functions are mostly unknown.

Show MeSH
Related in: MedlinePlus