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Targeting the angiotensin II type 2 receptor (AT2R) in colorectal liver metastases.

Ager EI, Chong WW, Wen SW, Christophi C - Cancer Cell Int. (2010)

Bottom Line: This increase in VEGF secretion by MoCRs was confirmed in vitro.These results suggest that AT2R activation might provide a novel target to inhibit tumour growth.Its potential to stimulate angiogenesis could be compensated by combination with anti-angiogenic agents.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Surgery, The University of Melbourne, Austin Health, Heidelberg, Victoria, Australia. eager@unimelb.edu.au.

ABSTRACT

Background: Blockade of the angiotensin (ANG) II type 1 receptor (AT1R) inhibits tumour growth in several cancers, including colorectal cancer (CRC) liver metastases. While AT1R blockade has been extensively studied, the potential of targeting the antagonistically acting AT2R in cancer has not been investigated. This study examined the effect of AT2R activation with the agonist CGP42112A in a mouse model of CRC liver metastases.

Results: In vitro, mouse CRC cell (MoCR) proliferation was inhibited by treatment with CGP42112A in a dose dependent manner while apoptosis was increased. Immunofluorescent staining for key signalling and secondary messengers, PLA2 and iNOS, were also increased by CGP42112A treatment in vitro. Immunohistochemical staining for proliferation (PCNA) and the apoptosis (active caspase 3) markers confirmed a CGP42112A-associated inhibition of proliferation and induction of apoptosis of mouse CRC cells (MoCR) in vivo. However, angiogenesis and vascular endothelial growth factor (VEGF) appeared to be increased by CGP42112A treatment in vivo. This increase in VEGF secretion by MoCRs was confirmed in vitro. Despite this apparent pro-angiogenic effect, a syngenic orthotopic mouse model of CRC liver metastases showed a reduction in liver to body weight ratio, an indication of tumour burden, following CGP42112A treatment compared to untreated controls.

Conclusions: These results suggest that AT2R activation might provide a novel target to inhibit tumour growth. Its potential to stimulate angiogenesis could be compensated by combination with anti-angiogenic agents.

No MeSH data available.


Related in: MedlinePlus

CFSE staining of MoCR cells after 24 (A) and 120 (C) hours of treatment. The percent of cells at each cell division was assessed by measuring the level of CFSE fluorescence by FACs. Only divisions with sufficient numbers of cells were assessed. At 24 hours almost all cells were either undivided or had divided twice, while by 120 hours all cells had divided at least 8 times. Proliferation was, in general, inhibited by CGP42112A treatment as indicated by the lower percentage of cells with more divisions. Reduced divisions were also seen at divisions 5 to 7 at time points 48 and 72 hours (P values between 0.058 and 0.088). Significant P values are shown with an * and solid line, while those of interest with P values between 0.1 and 0.05 are indicated with a dotted line and no *. Data are presented as mean ± S.E.M.
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Figure 1: CFSE staining of MoCR cells after 24 (A) and 120 (C) hours of treatment. The percent of cells at each cell division was assessed by measuring the level of CFSE fluorescence by FACs. Only divisions with sufficient numbers of cells were assessed. At 24 hours almost all cells were either undivided or had divided twice, while by 120 hours all cells had divided at least 8 times. Proliferation was, in general, inhibited by CGP42112A treatment as indicated by the lower percentage of cells with more divisions. Reduced divisions were also seen at divisions 5 to 7 at time points 48 and 72 hours (P values between 0.058 and 0.088). Significant P values are shown with an * and solid line, while those of interest with P values between 0.1 and 0.05 are indicated with a dotted line and no *. Data are presented as mean ± S.E.M.

Mentions: No significant difference was found in the percent of non-dividing cells between treatments (either in a background of 0.1% FBS or 2% FBS) after 24 hours of treatment (Figure 1A). However, the percentage of cells that divided twice over 24 hours was significantly reduced by 1 μM CGP42112A treatment compared to 2% FBS control (P = 0.0370, t-test). This was not the case when cells were cultured in a 0.1% FBS background. Similar reductions (although failing to reach significance, P between 0.058 and 0.088) were seen for 48 and 72 hour treatments (data not shown). After 120 hours, proliferation in both the 0.1% FBS and 2% FBS background was inhibited by CGP42112A treatment with the higher concentration having a greater inhibitory effect. This was evident by the increase in the percent of treated cells in the 7th and 8th divisions (P ≤ 0.0479) in the 2% FBS background compared to the percent in the later 9 th and 10 th divisions, in which there were more control than treated cells and significantly so for the 10th division (P ≤ 0.0030) (Figure 1B). In the 0.1% FBS background all divisions between 7 and 10, with the 7th significantly reduced (P = 0.049), by 1 μM CGP42112A treatment.


Targeting the angiotensin II type 2 receptor (AT2R) in colorectal liver metastases.

Ager EI, Chong WW, Wen SW, Christophi C - Cancer Cell Int. (2010)

CFSE staining of MoCR cells after 24 (A) and 120 (C) hours of treatment. The percent of cells at each cell division was assessed by measuring the level of CFSE fluorescence by FACs. Only divisions with sufficient numbers of cells were assessed. At 24 hours almost all cells were either undivided or had divided twice, while by 120 hours all cells had divided at least 8 times. Proliferation was, in general, inhibited by CGP42112A treatment as indicated by the lower percentage of cells with more divisions. Reduced divisions were also seen at divisions 5 to 7 at time points 48 and 72 hours (P values between 0.058 and 0.088). Significant P values are shown with an * and solid line, while those of interest with P values between 0.1 and 0.05 are indicated with a dotted line and no *. Data are presented as mean ± S.E.M.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2902462&req=5

Figure 1: CFSE staining of MoCR cells after 24 (A) and 120 (C) hours of treatment. The percent of cells at each cell division was assessed by measuring the level of CFSE fluorescence by FACs. Only divisions with sufficient numbers of cells were assessed. At 24 hours almost all cells were either undivided or had divided twice, while by 120 hours all cells had divided at least 8 times. Proliferation was, in general, inhibited by CGP42112A treatment as indicated by the lower percentage of cells with more divisions. Reduced divisions were also seen at divisions 5 to 7 at time points 48 and 72 hours (P values between 0.058 and 0.088). Significant P values are shown with an * and solid line, while those of interest with P values between 0.1 and 0.05 are indicated with a dotted line and no *. Data are presented as mean ± S.E.M.
Mentions: No significant difference was found in the percent of non-dividing cells between treatments (either in a background of 0.1% FBS or 2% FBS) after 24 hours of treatment (Figure 1A). However, the percentage of cells that divided twice over 24 hours was significantly reduced by 1 μM CGP42112A treatment compared to 2% FBS control (P = 0.0370, t-test). This was not the case when cells were cultured in a 0.1% FBS background. Similar reductions (although failing to reach significance, P between 0.058 and 0.088) were seen for 48 and 72 hour treatments (data not shown). After 120 hours, proliferation in both the 0.1% FBS and 2% FBS background was inhibited by CGP42112A treatment with the higher concentration having a greater inhibitory effect. This was evident by the increase in the percent of treated cells in the 7th and 8th divisions (P ≤ 0.0479) in the 2% FBS background compared to the percent in the later 9 th and 10 th divisions, in which there were more control than treated cells and significantly so for the 10th division (P ≤ 0.0030) (Figure 1B). In the 0.1% FBS background all divisions between 7 and 10, with the 7th significantly reduced (P = 0.049), by 1 μM CGP42112A treatment.

Bottom Line: This increase in VEGF secretion by MoCRs was confirmed in vitro.These results suggest that AT2R activation might provide a novel target to inhibit tumour growth.Its potential to stimulate angiogenesis could be compensated by combination with anti-angiogenic agents.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Surgery, The University of Melbourne, Austin Health, Heidelberg, Victoria, Australia. eager@unimelb.edu.au.

ABSTRACT

Background: Blockade of the angiotensin (ANG) II type 1 receptor (AT1R) inhibits tumour growth in several cancers, including colorectal cancer (CRC) liver metastases. While AT1R blockade has been extensively studied, the potential of targeting the antagonistically acting AT2R in cancer has not been investigated. This study examined the effect of AT2R activation with the agonist CGP42112A in a mouse model of CRC liver metastases.

Results: In vitro, mouse CRC cell (MoCR) proliferation was inhibited by treatment with CGP42112A in a dose dependent manner while apoptosis was increased. Immunofluorescent staining for key signalling and secondary messengers, PLA2 and iNOS, were also increased by CGP42112A treatment in vitro. Immunohistochemical staining for proliferation (PCNA) and the apoptosis (active caspase 3) markers confirmed a CGP42112A-associated inhibition of proliferation and induction of apoptosis of mouse CRC cells (MoCR) in vivo. However, angiogenesis and vascular endothelial growth factor (VEGF) appeared to be increased by CGP42112A treatment in vivo. This increase in VEGF secretion by MoCRs was confirmed in vitro. Despite this apparent pro-angiogenic effect, a syngenic orthotopic mouse model of CRC liver metastases showed a reduction in liver to body weight ratio, an indication of tumour burden, following CGP42112A treatment compared to untreated controls.

Conclusions: These results suggest that AT2R activation might provide a novel target to inhibit tumour growth. Its potential to stimulate angiogenesis could be compensated by combination with anti-angiogenic agents.

No MeSH data available.


Related in: MedlinePlus