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Combinatorial targeting of FGF and ErbB receptors blocks growth and metastatic spread of breast cancer models.

Issa A, Gill JW, Heideman MR, Sahin O, Wiemann S, Dey JH, Hynes NE - Breast Cancer Res. (2013)

Bottom Line: The results show that in vivo these breast cancer models become dependent upon co-activation of FGFR and ErbB receptors for PI3K pathway activity.The work presented here shows that in the breast cancer models examined, the combination of dovitinib + NVP-BEZ235 or dovitinib + AEE788 results in strong inhibition of tumor growth and a block in metastatic spread.The resultant decrease in mitosis and increase in apoptosis was consistently stronger in the dovitinib + AEE788 treatment-group, suggesting that targeting ErbB receptors has broader downstream effects compared to targeting only PI3K/mTOR.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Introduction: Targeting receptor tyrosine kinases (RTKs) with kinase inhibitors is a clinically validated anti-cancer approach. However, blocking one signaling pathway is often not sufficient to cause tumor regression and the effectiveness of individual inhibitors is often short-lived. As alterations in fibroblast growth factor receptor (FGFR) activity have been implicated in breast cancer, we examined in breast cancer models with autocrine FGFR activity the impact of targeting FGFRs in vivo with a selective kinase inhibitor in combination with an inhibitor of PI3K/mTOR or with a pan-ErbB inhibitor.

Methods: Using 4T1 or 67NR models of basal-like breast cancer, tumor growth was measured in mice treated with an FGFR inhibitor (dovitinib/TKI258), a PI3K/mTOR inhibitor (NVP-BEZ235) or a pan-ErbB inhibitor (AEE788) individually or in combination. To uncover mechanisms underlying inhibitor action, signaling pathway activity was examined in tumor lysates and transcriptome analysis carried out to identify pathways upregulated by FGFR inhibition. Anti-phosphotyrosine receptor antibody arrays (P-Tyr RTK) were also used to screen 4T1 tumors.

Results: The combination of dovitinib + NVP-BEZ235 causes tumor stasis and strong down-regulation of the FRS2/Erk and PI3K/Akt/mTOR signaling pathways. P-Tyr RTK arrays identified high levels of P-EGFR and P-ErbB2 in 4T1 tumors. Testing AEE788 in the tumor models revealed that the combination of dovitinib + AEE788 resulted in blockade of the PI3K/Akt/mTOR pathway, prolonged tumor stasis and in the 4T1 model, a significant decrease in lung metastasis. The results show that in vivo these breast cancer models become dependent upon co-activation of FGFR and ErbB receptors for PI3K pathway activity.

Conclusions: The work presented here shows that in the breast cancer models examined, the combination of dovitinib + NVP-BEZ235 or dovitinib + AEE788 results in strong inhibition of tumor growth and a block in metastatic spread. Only these combinations strongly down-regulate the FGFR/FRS2/Erk and PI3K/Akt/mTOR signaling pathways. The resultant decrease in mitosis and increase in apoptosis was consistently stronger in the dovitinib + AEE788 treatment-group, suggesting that targeting ErbB receptors has broader downstream effects compared to targeting only PI3K/mTOR. Considering that sub-classes of human breast tumors co-express ErbB receptors and FGFRs, these results have implications for targeted therapy.

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4T1 and 67NR tumors retain prolonged sensitivity to treatment with the dovitinib + NVP-BEZ235 combination. (A) Groups of 67NR tumor-bearing mice (n = 5) were treated daily with vehicle (PEG300), or with a combination of dovitinib (TKI, 20 mg/kg) and NVP-BEZ235 (10 mg/kg) for 7 days. Treatment was stopped for 5 days then resumed for 6 days and tumor growth was monitored. (B) Groups of 4T1 tumor-bearing mice (n = 6) were treated daily with vehicle (PEG300) or the combination of dovitinib (TKI, 20 mg/kg) + NVP-BEZ235 (10 mg/kg). After 10 days treatment, residual tumors were enzymatically digested, hematopoietic cell-depleted and 0.5 × 106 were re-injected into naïve mice (scheme in top panel). Starting 7 days after injection, groups of mice (n = 5) were treated daily for 11 days with (PEG300), dovitinib (TKI, 20 mg/kg), NVP-BEZ235 (10 mg/kg) or a combination of both, and tumor growth was monitored (lower portion of B). *P < 0.05 (Mann-Whitney U-test).
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Figure 3: 4T1 and 67NR tumors retain prolonged sensitivity to treatment with the dovitinib + NVP-BEZ235 combination. (A) Groups of 67NR tumor-bearing mice (n = 5) were treated daily with vehicle (PEG300), or with a combination of dovitinib (TKI, 20 mg/kg) and NVP-BEZ235 (10 mg/kg) for 7 days. Treatment was stopped for 5 days then resumed for 6 days and tumor growth was monitored. (B) Groups of 4T1 tumor-bearing mice (n = 6) were treated daily with vehicle (PEG300) or the combination of dovitinib (TKI, 20 mg/kg) + NVP-BEZ235 (10 mg/kg). After 10 days treatment, residual tumors were enzymatically digested, hematopoietic cell-depleted and 0.5 × 106 were re-injected into naïve mice (scheme in top panel). Starting 7 days after injection, groups of mice (n = 5) were treated daily for 11 days with (PEG300), dovitinib (TKI, 20 mg/kg), NVP-BEZ235 (10 mg/kg) or a combination of both, and tumor growth was monitored (lower portion of B). *P < 0.05 (Mann-Whitney U-test).

Mentions: The 67NR tumor-bearing mice were also examined for their sensitivity to the dovitinib + NVP-BEZ235 combination. As observed in the 4T1 model, this treatment was very effective in blocking the PI3K/Akt/mTOR pathway in the tumors (see Figure S3 in Additional file 1) and after 7 days tumor growth was essentially blocked (Figure 3A). Mice removed from treatment were monitored and regrowth was observed after approximately 5 days. Importantly, the tumors responded well to a second treatment and even appeared to regress over the course of the last 4 days of the experiment (Figure 3A). Thus, 67NR tumors, like 4T1 tumors, are also very sensitive to treatment with the FGFR inhibitor in combination with the PI3K/mTOR inhibitor NVP-BEZ235.


Combinatorial targeting of FGF and ErbB receptors blocks growth and metastatic spread of breast cancer models.

Issa A, Gill JW, Heideman MR, Sahin O, Wiemann S, Dey JH, Hynes NE - Breast Cancer Res. (2013)

4T1 and 67NR tumors retain prolonged sensitivity to treatment with the dovitinib + NVP-BEZ235 combination. (A) Groups of 67NR tumor-bearing mice (n = 5) were treated daily with vehicle (PEG300), or with a combination of dovitinib (TKI, 20 mg/kg) and NVP-BEZ235 (10 mg/kg) for 7 days. Treatment was stopped for 5 days then resumed for 6 days and tumor growth was monitored. (B) Groups of 4T1 tumor-bearing mice (n = 6) were treated daily with vehicle (PEG300) or the combination of dovitinib (TKI, 20 mg/kg) + NVP-BEZ235 (10 mg/kg). After 10 days treatment, residual tumors were enzymatically digested, hematopoietic cell-depleted and 0.5 × 106 were re-injected into naïve mice (scheme in top panel). Starting 7 days after injection, groups of mice (n = 5) were treated daily for 11 days with (PEG300), dovitinib (TKI, 20 mg/kg), NVP-BEZ235 (10 mg/kg) or a combination of both, and tumor growth was monitored (lower portion of B). *P < 0.05 (Mann-Whitney U-test).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3672810&req=5

Figure 3: 4T1 and 67NR tumors retain prolonged sensitivity to treatment with the dovitinib + NVP-BEZ235 combination. (A) Groups of 67NR tumor-bearing mice (n = 5) were treated daily with vehicle (PEG300), or with a combination of dovitinib (TKI, 20 mg/kg) and NVP-BEZ235 (10 mg/kg) for 7 days. Treatment was stopped for 5 days then resumed for 6 days and tumor growth was monitored. (B) Groups of 4T1 tumor-bearing mice (n = 6) were treated daily with vehicle (PEG300) or the combination of dovitinib (TKI, 20 mg/kg) + NVP-BEZ235 (10 mg/kg). After 10 days treatment, residual tumors were enzymatically digested, hematopoietic cell-depleted and 0.5 × 106 were re-injected into naïve mice (scheme in top panel). Starting 7 days after injection, groups of mice (n = 5) were treated daily for 11 days with (PEG300), dovitinib (TKI, 20 mg/kg), NVP-BEZ235 (10 mg/kg) or a combination of both, and tumor growth was monitored (lower portion of B). *P < 0.05 (Mann-Whitney U-test).
Mentions: The 67NR tumor-bearing mice were also examined for their sensitivity to the dovitinib + NVP-BEZ235 combination. As observed in the 4T1 model, this treatment was very effective in blocking the PI3K/Akt/mTOR pathway in the tumors (see Figure S3 in Additional file 1) and after 7 days tumor growth was essentially blocked (Figure 3A). Mice removed from treatment were monitored and regrowth was observed after approximately 5 days. Importantly, the tumors responded well to a second treatment and even appeared to regress over the course of the last 4 days of the experiment (Figure 3A). Thus, 67NR tumors, like 4T1 tumors, are also very sensitive to treatment with the FGFR inhibitor in combination with the PI3K/mTOR inhibitor NVP-BEZ235.

Bottom Line: The results show that in vivo these breast cancer models become dependent upon co-activation of FGFR and ErbB receptors for PI3K pathway activity.The work presented here shows that in the breast cancer models examined, the combination of dovitinib + NVP-BEZ235 or dovitinib + AEE788 results in strong inhibition of tumor growth and a block in metastatic spread.The resultant decrease in mitosis and increase in apoptosis was consistently stronger in the dovitinib + AEE788 treatment-group, suggesting that targeting ErbB receptors has broader downstream effects compared to targeting only PI3K/mTOR.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Introduction: Targeting receptor tyrosine kinases (RTKs) with kinase inhibitors is a clinically validated anti-cancer approach. However, blocking one signaling pathway is often not sufficient to cause tumor regression and the effectiveness of individual inhibitors is often short-lived. As alterations in fibroblast growth factor receptor (FGFR) activity have been implicated in breast cancer, we examined in breast cancer models with autocrine FGFR activity the impact of targeting FGFRs in vivo with a selective kinase inhibitor in combination with an inhibitor of PI3K/mTOR or with a pan-ErbB inhibitor.

Methods: Using 4T1 or 67NR models of basal-like breast cancer, tumor growth was measured in mice treated with an FGFR inhibitor (dovitinib/TKI258), a PI3K/mTOR inhibitor (NVP-BEZ235) or a pan-ErbB inhibitor (AEE788) individually or in combination. To uncover mechanisms underlying inhibitor action, signaling pathway activity was examined in tumor lysates and transcriptome analysis carried out to identify pathways upregulated by FGFR inhibition. Anti-phosphotyrosine receptor antibody arrays (P-Tyr RTK) were also used to screen 4T1 tumors.

Results: The combination of dovitinib + NVP-BEZ235 causes tumor stasis and strong down-regulation of the FRS2/Erk and PI3K/Akt/mTOR signaling pathways. P-Tyr RTK arrays identified high levels of P-EGFR and P-ErbB2 in 4T1 tumors. Testing AEE788 in the tumor models revealed that the combination of dovitinib + AEE788 resulted in blockade of the PI3K/Akt/mTOR pathway, prolonged tumor stasis and in the 4T1 model, a significant decrease in lung metastasis. The results show that in vivo these breast cancer models become dependent upon co-activation of FGFR and ErbB receptors for PI3K pathway activity.

Conclusions: The work presented here shows that in the breast cancer models examined, the combination of dovitinib + NVP-BEZ235 or dovitinib + AEE788 results in strong inhibition of tumor growth and a block in metastatic spread. Only these combinations strongly down-regulate the FGFR/FRS2/Erk and PI3K/Akt/mTOR signaling pathways. The resultant decrease in mitosis and increase in apoptosis was consistently stronger in the dovitinib + AEE788 treatment-group, suggesting that targeting ErbB receptors has broader downstream effects compared to targeting only PI3K/mTOR. Considering that sub-classes of human breast tumors co-express ErbB receptors and FGFRs, these results have implications for targeted therapy.

Show MeSH
Related in: MedlinePlus