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Image based detection and targeting of therapy resistance in pancreatic adenocarcinoma

View Article: PubMed Central - PubMed

ABSTRACT

Pancreatic intraepithelial neoplasia (PanIN) is a premalignant lesion that can progress to pancreatic ductal adenocarcinoma, a highly lethal malignancy marked by its late stage at clinical presentation and profound drug resistance1. The genomic alterations that commonly occur in pancreatic cancer include activation of KRAS2 and inactivation of p53, and SMAD42-4. To date, however, it has been challenging to target these pathways therapeutically; thus the search for other key mediators of pancreatic cancer growth remains an important endeavor. Here we show that the stem cell determinant Musashi (Msi) is a critical element of pancreatic cancer progression in both genetic models and patient derived xenografts. Specifically, we developed Msi reporter mice that allowed image based tracking of stem cell signals within cancers, revealing that Msi expression rises as PanIN progresses to adenocarcinoma, and that Msi-expressing cells are key drivers of pancreatic cancer: they preferentially harbor the capacity to propagate adenocarcinoma, are enriched in circulating tumor cells, and are markedly drug resistant. This population could be effectively targeted by deletion of either Msi1 or Msi2, which led to a striking defect in PanIN progression to adenocarcinoma and an improvement in overall survival. Msi inhibition also blocked the growth of primary patient-derived tumors, suggesting that this signal is required for human disease. To define the translational potential of this work we developed antisense oligonucleotides against Msi; these showed reliable tumor penetration, uptake and target inhibition, and effectively blocked pancreatic cancer growth. Collectively, these studies highlight Msi reporters as a unique tool to identify therapy resistance, and define Msi signaling as a central regulator of pancreatic cancer.

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Targeting MSI inhibits pancreatic cancer growth in patient-derived xenografts(a-b) Frequency of GFP+ tumor cells before and after transplantation. (c) MSI1 expression following MSI1-ASO free uptake in human pancreatic cancer line (n=3 independent experiments/dose). (d) Colony formation of control or MSI1-ASO treated human pancreatic cancer line (n=3 independent experiments). (e) In vivo growth of human cell line-derived tumors in control or MSI1-ASO treated mice (n=10). (f) Relative tumor volume and (g) rate of growth of KPf/fC-derived tumors in control or MSI1-ASO treated mice (n=8). (h) Malat1 expression in autocthonous KPf/fC tumors following systemic delivery of lead-optimized control or Malat1-ASO (n=6). Data represented as mean ± SEM. * P < 0.05, ** P < 0.01, *** P < 0.001 by One-way ANOVA. ns, not significant. Source Data for all panels are available online.
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Figure 4: Targeting MSI inhibits pancreatic cancer growth in patient-derived xenografts(a-b) Frequency of GFP+ tumor cells before and after transplantation. (c) MSI1 expression following MSI1-ASO free uptake in human pancreatic cancer line (n=3 independent experiments/dose). (d) Colony formation of control or MSI1-ASO treated human pancreatic cancer line (n=3 independent experiments). (e) In vivo growth of human cell line-derived tumors in control or MSI1-ASO treated mice (n=10). (f) Relative tumor volume and (g) rate of growth of KPf/fC-derived tumors in control or MSI1-ASO treated mice (n=8). (h) Malat1 expression in autocthonous KPf/fC tumors following systemic delivery of lead-optimized control or Malat1-ASO (n=6). Data represented as mean ± SEM. * P < 0.05, ** P < 0.01, *** P < 0.001 by One-way ANOVA. ns, not significant. Source Data for all panels are available online.

Mentions: To complement the mouse models, we tested the impact of MSI inhibition on primary patient samples, which harbor more complex mutations, and are uniformly drug resistant. Primary pancreatic cancer cells were infected with MSI shRNAs and xenografted (Extended Data Fig. 8a). While shMSI cells were equivalently present at time of transplant, their ability to contribute to the tumor mass in vivo was reduced by 4.9-6.5 fold (Fig. 4a-b, Extended Data Fig. 8b-c), demonstrating that inhibition of either MSI1 or MSI2 results in marked suppression of primary human pancreatic cancer growth. Interestingly, MSI2 expression was more homogeneous in patients than in mouse models (Extended Data Fig. 1a-b, 2d-e). This could be a consequence of selection due to treatment and end-stage disease in patients, or because MSI2 patterns differ between mouse models and human disease. However, regardless of the level of heterogeneity, our loss-of-function studies indicate that the mouse and human disease are both highly dependent on Msi signaling.


Image based detection and targeting of therapy resistance in pancreatic adenocarcinoma
Targeting MSI inhibits pancreatic cancer growth in patient-derived xenografts(a-b) Frequency of GFP+ tumor cells before and after transplantation. (c) MSI1 expression following MSI1-ASO free uptake in human pancreatic cancer line (n=3 independent experiments/dose). (d) Colony formation of control or MSI1-ASO treated human pancreatic cancer line (n=3 independent experiments). (e) In vivo growth of human cell line-derived tumors in control or MSI1-ASO treated mice (n=10). (f) Relative tumor volume and (g) rate of growth of KPf/fC-derived tumors in control or MSI1-ASO treated mice (n=8). (h) Malat1 expression in autocthonous KPf/fC tumors following systemic delivery of lead-optimized control or Malat1-ASO (n=6). Data represented as mean ± SEM. * P < 0.05, ** P < 0.01, *** P < 0.001 by One-way ANOVA. ns, not significant. Source Data for all panels are available online.
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Figure 4: Targeting MSI inhibits pancreatic cancer growth in patient-derived xenografts(a-b) Frequency of GFP+ tumor cells before and after transplantation. (c) MSI1 expression following MSI1-ASO free uptake in human pancreatic cancer line (n=3 independent experiments/dose). (d) Colony formation of control or MSI1-ASO treated human pancreatic cancer line (n=3 independent experiments). (e) In vivo growth of human cell line-derived tumors in control or MSI1-ASO treated mice (n=10). (f) Relative tumor volume and (g) rate of growth of KPf/fC-derived tumors in control or MSI1-ASO treated mice (n=8). (h) Malat1 expression in autocthonous KPf/fC tumors following systemic delivery of lead-optimized control or Malat1-ASO (n=6). Data represented as mean ± SEM. * P < 0.05, ** P < 0.01, *** P < 0.001 by One-way ANOVA. ns, not significant. Source Data for all panels are available online.
Mentions: To complement the mouse models, we tested the impact of MSI inhibition on primary patient samples, which harbor more complex mutations, and are uniformly drug resistant. Primary pancreatic cancer cells were infected with MSI shRNAs and xenografted (Extended Data Fig. 8a). While shMSI cells were equivalently present at time of transplant, their ability to contribute to the tumor mass in vivo was reduced by 4.9-6.5 fold (Fig. 4a-b, Extended Data Fig. 8b-c), demonstrating that inhibition of either MSI1 or MSI2 results in marked suppression of primary human pancreatic cancer growth. Interestingly, MSI2 expression was more homogeneous in patients than in mouse models (Extended Data Fig. 1a-b, 2d-e). This could be a consequence of selection due to treatment and end-stage disease in patients, or because MSI2 patterns differ between mouse models and human disease. However, regardless of the level of heterogeneity, our loss-of-function studies indicate that the mouse and human disease are both highly dependent on Msi signaling.

View Article: PubMed Central - PubMed

ABSTRACT

Pancreatic intraepithelial neoplasia (PanIN) is a premalignant lesion that can progress to pancreatic ductal adenocarcinoma, a highly lethal malignancy marked by its late stage at clinical presentation and profound drug resistance1. The genomic alterations that commonly occur in pancreatic cancer include activation of KRAS2 and inactivation of p53, and SMAD42-4. To date, however, it has been challenging to target these pathways therapeutically; thus the search for other key mediators of pancreatic cancer growth remains an important endeavor. Here we show that the stem cell determinant Musashi (Msi) is a critical element of pancreatic cancer progression in both genetic models and patient derived xenografts. Specifically, we developed Msi reporter mice that allowed image based tracking of stem cell signals within cancers, revealing that Msi expression rises as PanIN progresses to adenocarcinoma, and that Msi-expressing cells are key drivers of pancreatic cancer: they preferentially harbor the capacity to propagate adenocarcinoma, are enriched in circulating tumor cells, and are markedly drug resistant. This population could be effectively targeted by deletion of either Msi1 or Msi2, which led to a striking defect in PanIN progression to adenocarcinoma and an improvement in overall survival. Msi inhibition also blocked the growth of primary patient-derived tumors, suggesting that this signal is required for human disease. To define the translational potential of this work we developed antisense oligonucleotides against Msi; these showed reliable tumor penetration, uptake and target inhibition, and effectively blocked pancreatic cancer growth. Collectively, these studies highlight Msi reporters as a unique tool to identify therapy resistance, and define Msi signaling as a central regulator of pancreatic cancer.

No MeSH data available.


Related in: MedlinePlus