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Pleiotropic modes of action in tumor cells of RNASET2, an evolutionary highly conserved extracellular RNase.

Lualdi M, Pedrini E, Rea K, Monti L, Scaldaferri D, Gariboldi M, Camporeale A, Ghia P, Monti E, Tomassetti A, Acquati F, Taramelli R - Oncotarget (2015)

Bottom Line: Indeed, RNASET2 expression levels were consistently found to increase following stress induction.Of note, a remarkable rearrangement of the actin cytoskeleton organization, together with changes in cell adhesion and motility, emerged as putative mechanisms by which such cell-autonomous role could occur.Altogether, these biological features allow to put forward the hypothesis that the RNASET2 protein can act as a molecular barrier for limiting the damages and tissue remodeling events occurring during the earlier step of cell transformation.

View Article: PubMed Central - PubMed

Affiliation: Department of Theoretical and Applied Sciences, Università degli Studi dell'Insubria, Varese, Italy.

ABSTRACT
As widely recognized, tumor growth entails a close and complex cross-talk among cancer cells and the surrounding tumor microenvironment. We recently described the human RNASET2 gene as one key player of such microenvironmental cross-talk. Indeed, the protein encoded by this gene is an extracellular RNase which is able to control cancer growth in a non-cell autonomous mode by inducing a sustained recruitment of immune-competent cells belonging to the monocyte/macrophage lineage within a growing tumor mass. Here, we asked whether this oncosuppressor gene is sensitive to stress challenges and whether it can trigger cell-intrinsic processes as well. Indeed, RNASET2 expression levels were consistently found to increase following stress induction. Moreover, changes in RNASET2 expression levels turned out to affect several cancer-related parameters in vitro in an ovarian cancer cell line model. Of note, a remarkable rearrangement of the actin cytoskeleton organization, together with changes in cell adhesion and motility, emerged as putative mechanisms by which such cell-autonomous role could occur. Altogether, these biological features allow to put forward the hypothesis that the RNASET2 protein can act as a molecular barrier for limiting the damages and tissue remodeling events occurring during the earlier step of cell transformation.

No MeSH data available.


Related in: MedlinePlus

Human RNASET2 protein levels change following stress inductionA) Eight different stress-inducing conditions were applied to four different cell lines and Western blot analysis for RNASET2 protein was performed. Relative fold-changes in RNASET2 expression are reported in treated vs. untreated cells, with dark and light shadows representing higher or lower levels with respect to untreated cells, respectively. B, C) Western Blot analysis data on total protein extracts (B) and supernatants (C). A significant increase in the levels of the intracellular 36 kDa RNASET2 protein was observed in response to both chemically-induced (CoCl2) and real (1% O2) hypoxic conditions. HIF-1α protein levels were assessed as an hypoxia stress marker. A concomitant increase of the secreted 36 kDa RNASET2 protein (EC RNASET2) was also observed in SKOV3 cells in response to chemically-induced hypoxia. Triplicate experiments were performed for each experimental condition assessed. Statistical analysis was performed using two-tailed Student's t-test. *p<0,05; **p<0,01; ***p<0,001. UT: untreated. IC: intracellular. EC: extracellular. FC: fold-change.
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Figure 2: Human RNASET2 protein levels change following stress inductionA) Eight different stress-inducing conditions were applied to four different cell lines and Western blot analysis for RNASET2 protein was performed. Relative fold-changes in RNASET2 expression are reported in treated vs. untreated cells, with dark and light shadows representing higher or lower levels with respect to untreated cells, respectively. B, C) Western Blot analysis data on total protein extracts (B) and supernatants (C). A significant increase in the levels of the intracellular 36 kDa RNASET2 protein was observed in response to both chemically-induced (CoCl2) and real (1% O2) hypoxic conditions. HIF-1α protein levels were assessed as an hypoxia stress marker. A concomitant increase of the secreted 36 kDa RNASET2 protein (EC RNASET2) was also observed in SKOV3 cells in response to chemically-induced hypoxia. Triplicate experiments were performed for each experimental condition assessed. Statistical analysis was performed using two-tailed Student's t-test. *p<0,05; **p<0,01; ***p<0,001. UT: untreated. IC: intracellular. EC: extracellular. FC: fold-change.

Mentions: Several stress conditions were therefore applied to a panel of human ovarian cancer cell lines (Hey3Met2, SKOV3 and OVCAR3) and the non-ovarian HeLa cell line and protein levels were subsequently assessed by immunoblotting. Stress conditions included heat shock, aminoacid starvation, UV irradiation, hypoxia, metabolic, oxidative and osmotic stresses. A summary of the results is shown in Figure 2A. Overall, we observed a clear trend for an increase in RNASET2 expression in ovarian cells under several stress conditions. Specifically, RNASET2 protein levels were increased in response to: 1) hypoxia, metabolic stress, oxidative stress and aminoacid starvation in Hey3Met2 cells; 2) hypoxia, oxidative stress and aminoacid starvation in SKOV3 cells, and 3) hypoxia, UV irradiation and aminoacid starvation in OVCAR3 cells. By contrast, either an increase or a decrease in RNASET2 expression was detected in HeLa cells depending on the stress condition applied. Noteworthy, chemically-induced hypoxia represented the only stress condition for which an increase in RNASET2 expression was found for all cell lines tested (Figure 2B).


Pleiotropic modes of action in tumor cells of RNASET2, an evolutionary highly conserved extracellular RNase.

Lualdi M, Pedrini E, Rea K, Monti L, Scaldaferri D, Gariboldi M, Camporeale A, Ghia P, Monti E, Tomassetti A, Acquati F, Taramelli R - Oncotarget (2015)

Human RNASET2 protein levels change following stress inductionA) Eight different stress-inducing conditions were applied to four different cell lines and Western blot analysis for RNASET2 protein was performed. Relative fold-changes in RNASET2 expression are reported in treated vs. untreated cells, with dark and light shadows representing higher or lower levels with respect to untreated cells, respectively. B, C) Western Blot analysis data on total protein extracts (B) and supernatants (C). A significant increase in the levels of the intracellular 36 kDa RNASET2 protein was observed in response to both chemically-induced (CoCl2) and real (1% O2) hypoxic conditions. HIF-1α protein levels were assessed as an hypoxia stress marker. A concomitant increase of the secreted 36 kDa RNASET2 protein (EC RNASET2) was also observed in SKOV3 cells in response to chemically-induced hypoxia. Triplicate experiments were performed for each experimental condition assessed. Statistical analysis was performed using two-tailed Student's t-test. *p<0,05; **p<0,01; ***p<0,001. UT: untreated. IC: intracellular. EC: extracellular. FC: fold-change.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4480721&req=5

Figure 2: Human RNASET2 protein levels change following stress inductionA) Eight different stress-inducing conditions were applied to four different cell lines and Western blot analysis for RNASET2 protein was performed. Relative fold-changes in RNASET2 expression are reported in treated vs. untreated cells, with dark and light shadows representing higher or lower levels with respect to untreated cells, respectively. B, C) Western Blot analysis data on total protein extracts (B) and supernatants (C). A significant increase in the levels of the intracellular 36 kDa RNASET2 protein was observed in response to both chemically-induced (CoCl2) and real (1% O2) hypoxic conditions. HIF-1α protein levels were assessed as an hypoxia stress marker. A concomitant increase of the secreted 36 kDa RNASET2 protein (EC RNASET2) was also observed in SKOV3 cells in response to chemically-induced hypoxia. Triplicate experiments were performed for each experimental condition assessed. Statistical analysis was performed using two-tailed Student's t-test. *p<0,05; **p<0,01; ***p<0,001. UT: untreated. IC: intracellular. EC: extracellular. FC: fold-change.
Mentions: Several stress conditions were therefore applied to a panel of human ovarian cancer cell lines (Hey3Met2, SKOV3 and OVCAR3) and the non-ovarian HeLa cell line and protein levels were subsequently assessed by immunoblotting. Stress conditions included heat shock, aminoacid starvation, UV irradiation, hypoxia, metabolic, oxidative and osmotic stresses. A summary of the results is shown in Figure 2A. Overall, we observed a clear trend for an increase in RNASET2 expression in ovarian cells under several stress conditions. Specifically, RNASET2 protein levels were increased in response to: 1) hypoxia, metabolic stress, oxidative stress and aminoacid starvation in Hey3Met2 cells; 2) hypoxia, oxidative stress and aminoacid starvation in SKOV3 cells, and 3) hypoxia, UV irradiation and aminoacid starvation in OVCAR3 cells. By contrast, either an increase or a decrease in RNASET2 expression was detected in HeLa cells depending on the stress condition applied. Noteworthy, chemically-induced hypoxia represented the only stress condition for which an increase in RNASET2 expression was found for all cell lines tested (Figure 2B).

Bottom Line: Indeed, RNASET2 expression levels were consistently found to increase following stress induction.Of note, a remarkable rearrangement of the actin cytoskeleton organization, together with changes in cell adhesion and motility, emerged as putative mechanisms by which such cell-autonomous role could occur.Altogether, these biological features allow to put forward the hypothesis that the RNASET2 protein can act as a molecular barrier for limiting the damages and tissue remodeling events occurring during the earlier step of cell transformation.

View Article: PubMed Central - PubMed

Affiliation: Department of Theoretical and Applied Sciences, Università degli Studi dell'Insubria, Varese, Italy.

ABSTRACT
As widely recognized, tumor growth entails a close and complex cross-talk among cancer cells and the surrounding tumor microenvironment. We recently described the human RNASET2 gene as one key player of such microenvironmental cross-talk. Indeed, the protein encoded by this gene is an extracellular RNase which is able to control cancer growth in a non-cell autonomous mode by inducing a sustained recruitment of immune-competent cells belonging to the monocyte/macrophage lineage within a growing tumor mass. Here, we asked whether this oncosuppressor gene is sensitive to stress challenges and whether it can trigger cell-intrinsic processes as well. Indeed, RNASET2 expression levels were consistently found to increase following stress induction. Moreover, changes in RNASET2 expression levels turned out to affect several cancer-related parameters in vitro in an ovarian cancer cell line model. Of note, a remarkable rearrangement of the actin cytoskeleton organization, together with changes in cell adhesion and motility, emerged as putative mechanisms by which such cell-autonomous role could occur. Altogether, these biological features allow to put forward the hypothesis that the RNASET2 protein can act as a molecular barrier for limiting the damages and tissue remodeling events occurring during the earlier step of cell transformation.

No MeSH data available.


Related in: MedlinePlus