Limits...
Novel patient-derived xenograft mouse model for pancreatic acinar cell carcinoma demonstrates single agent activity of oxaliplatin.

Hall JC, Marlow LA, Mathias AC, Dawson LK, Durham WF, Meshaw KA, Mullin RJ, Synnott AJ, Small DL, Krishna M, von Hoff D, Schüler J, Hart SN, Couch FJ, Colon-Otero G, Copland JA - J Transl Med (2016)

Bottom Line: The model presented here expresses the same IHC markers found in human PACC.Bevacizumab also produced a significant growth response, but the effect was not prolonged as demonstrated by oxaliplatin treatment.The other chemotherapies had moderate to little effect, particularly after treatment ceased.

View Article: PubMed Central - PubMed

Affiliation: Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, 4500 San Pablo Road S., Jacksonville, FL, 32224, USA. Hall.Jason@mayo.edu.

ABSTRACT

Background: Pancreatic acinar cell carcinoma (PACC) is a rare malignancy, accounting for <1 % of all pancreatic neoplasms. Very few retrospective studies are available to help guide management. We previously reported the case of a patient with metastatic PACC who achieved prolonged survival following doxorubicin treatment. Personalized treatment was based on molecular and in vitro data collected from primary cells developed from their liver metastasis. We now report the characterization of a patient derived tumor xenograft (PDTX) mouse model that originated from this patient's PACC liver metastasis.

Methods: Fragments of biopsy tissue (5 mm(3)) from PACC liver metastasis were implanted into athymic nude mice. Tumors were grown and passaged from the host mice into new mice to be tested for therapeutic response. Immuno-histochemical (IHC) biomarkers were used to confirm that the PDTX model represents human PACC. The antitumor activities of multiple drugs (5-FU, irinotecan, oxaliplatin, gemcitabine, bevacizumab, erlotinib, doxorubicin and imatinib) were tested. Tumor size was measured over 74 days or until they reached an endpoint volume of ~800 mm(3). Tests to measure serum lipase levels and histological analyses of tumor tissues were also conducted to assess PACC progression and re-differentiation.

Results: The model presented here expresses the same IHC markers found in human PACC. In the chemotherapy study, oxaliplatin produced a prolonged durable growth response associated with increased apoptosis, decreased serum lipase levels and increased healthy acinar cells. Bevacizumab also produced a significant growth response, but the effect was not prolonged as demonstrated by oxaliplatin treatment. The other chemotherapies had moderate to little effect, particularly after treatment ceased. Mutations in DNA repair genes are common in PACC and increase tumor susceptibility to oxaliplatin. To explore this we performed IHC and found no nuclear expression of BRCA2 in our model, indicating a mutation affecting nuclear localization. Gene sequencing confirms BRCA2 has a homozygous gene deletion on Exon 10, which frequently causes a protein truncation.

Conclusions: In summary, we report the development and characterization of the first and only preclinical PACC PDTX model. Here we show sustained anti-tumor activity of single agent oxaliplatin, a compound that is more effective in tumors that harbor mutations in DNA repair genes. Our data shows that BRCA2 is mutated in our PACC model, which could contribute to the oxaliplatin sensitivity observed. Further studies on this rare PACC model can serve to elucidate other novel therapies, biomarkers, and molecular mechanisms of signaling and drug resistance.

No MeSH data available.


Related in: MedlinePlus

Immunofluorescence and genetic analysis indicates a BRCA2 mutation in the PA-018 PAAC model. a Immunofluorescence staining for BRCA1 and BRCA2. Panel i shows BRCA1 (red) expressed throughout the nucleus and cytoplasm in normal, PDAC, and the PAAC PDTX tissue. In panel ii, normal and PDAC tissue show co-localization of nuclear DAPI stain and BRCA2 but the PAAC PDTX tissue, does not have this co-localization, indicating that BRCA2 expression is confined to the cytoplasm. b Gene mutational analysis of BRCA2 confirms the presence a 5 base pair deletion on exon 10
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4862141&req=5

Fig6: Immunofluorescence and genetic analysis indicates a BRCA2 mutation in the PA-018 PAAC model. a Immunofluorescence staining for BRCA1 and BRCA2. Panel i shows BRCA1 (red) expressed throughout the nucleus and cytoplasm in normal, PDAC, and the PAAC PDTX tissue. In panel ii, normal and PDAC tissue show co-localization of nuclear DAPI stain and BRCA2 but the PAAC PDTX tissue, does not have this co-localization, indicating that BRCA2 expression is confined to the cytoplasm. b Gene mutational analysis of BRCA2 confirms the presence a 5 base pair deletion on exon 10

Mentions: An IF and IHC panel for BRCA1 and BRCA2 expression was performed on normal pancreas, pancreatic ductal adenocarcinoma (PDAC), and the PACC PDTX model. Both techniques demonstrate that nuclear BRCA1 is present in all tissue samples along with some cytoplasmic expression (Fig. 6a panel i; Additional file 3: Figure S2 panel i). Immunofluorescence shows that the PDTX model has no co-localization of BRCA2 and DAPI nuclear stain (Fig. 6a, panel ii). IHC on patient PACC tissue and its PDTX (PA-018) also show a lack of BRCA2 nuclear expression. Instead, only cytoplasmic expression in the islets and PACC tissue were observed (Additional file 3: Figure S2 panel ii). Mutational gene analysis of PA-018 PDX tissue was used to identify a 5 base pair deletion in BRCA2 (c.1755_1759del5) (Fig. 6b; Additional file 4: Figure S3). All sequence reads contained the mutated allele, indicating that there was no wild type BRCA2 allele present. This suggests a loss of heterozygosity (LOH) occurred in the tumor.Fig. 6


Novel patient-derived xenograft mouse model for pancreatic acinar cell carcinoma demonstrates single agent activity of oxaliplatin.

Hall JC, Marlow LA, Mathias AC, Dawson LK, Durham WF, Meshaw KA, Mullin RJ, Synnott AJ, Small DL, Krishna M, von Hoff D, Schüler J, Hart SN, Couch FJ, Colon-Otero G, Copland JA - J Transl Med (2016)

Immunofluorescence and genetic analysis indicates a BRCA2 mutation in the PA-018 PAAC model. a Immunofluorescence staining for BRCA1 and BRCA2. Panel i shows BRCA1 (red) expressed throughout the nucleus and cytoplasm in normal, PDAC, and the PAAC PDTX tissue. In panel ii, normal and PDAC tissue show co-localization of nuclear DAPI stain and BRCA2 but the PAAC PDTX tissue, does not have this co-localization, indicating that BRCA2 expression is confined to the cytoplasm. b Gene mutational analysis of BRCA2 confirms the presence a 5 base pair deletion on exon 10
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4862141&req=5

Fig6: Immunofluorescence and genetic analysis indicates a BRCA2 mutation in the PA-018 PAAC model. a Immunofluorescence staining for BRCA1 and BRCA2. Panel i shows BRCA1 (red) expressed throughout the nucleus and cytoplasm in normal, PDAC, and the PAAC PDTX tissue. In panel ii, normal and PDAC tissue show co-localization of nuclear DAPI stain and BRCA2 but the PAAC PDTX tissue, does not have this co-localization, indicating that BRCA2 expression is confined to the cytoplasm. b Gene mutational analysis of BRCA2 confirms the presence a 5 base pair deletion on exon 10
Mentions: An IF and IHC panel for BRCA1 and BRCA2 expression was performed on normal pancreas, pancreatic ductal adenocarcinoma (PDAC), and the PACC PDTX model. Both techniques demonstrate that nuclear BRCA1 is present in all tissue samples along with some cytoplasmic expression (Fig. 6a panel i; Additional file 3: Figure S2 panel i). Immunofluorescence shows that the PDTX model has no co-localization of BRCA2 and DAPI nuclear stain (Fig. 6a, panel ii). IHC on patient PACC tissue and its PDTX (PA-018) also show a lack of BRCA2 nuclear expression. Instead, only cytoplasmic expression in the islets and PACC tissue were observed (Additional file 3: Figure S2 panel ii). Mutational gene analysis of PA-018 PDX tissue was used to identify a 5 base pair deletion in BRCA2 (c.1755_1759del5) (Fig. 6b; Additional file 4: Figure S3). All sequence reads contained the mutated allele, indicating that there was no wild type BRCA2 allele present. This suggests a loss of heterozygosity (LOH) occurred in the tumor.Fig. 6

Bottom Line: The model presented here expresses the same IHC markers found in human PACC.Bevacizumab also produced a significant growth response, but the effect was not prolonged as demonstrated by oxaliplatin treatment.The other chemotherapies had moderate to little effect, particularly after treatment ceased.

View Article: PubMed Central - PubMed

Affiliation: Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, 4500 San Pablo Road S., Jacksonville, FL, 32224, USA. Hall.Jason@mayo.edu.

ABSTRACT

Background: Pancreatic acinar cell carcinoma (PACC) is a rare malignancy, accounting for <1 % of all pancreatic neoplasms. Very few retrospective studies are available to help guide management. We previously reported the case of a patient with metastatic PACC who achieved prolonged survival following doxorubicin treatment. Personalized treatment was based on molecular and in vitro data collected from primary cells developed from their liver metastasis. We now report the characterization of a patient derived tumor xenograft (PDTX) mouse model that originated from this patient's PACC liver metastasis.

Methods: Fragments of biopsy tissue (5 mm(3)) from PACC liver metastasis were implanted into athymic nude mice. Tumors were grown and passaged from the host mice into new mice to be tested for therapeutic response. Immuno-histochemical (IHC) biomarkers were used to confirm that the PDTX model represents human PACC. The antitumor activities of multiple drugs (5-FU, irinotecan, oxaliplatin, gemcitabine, bevacizumab, erlotinib, doxorubicin and imatinib) were tested. Tumor size was measured over 74 days or until they reached an endpoint volume of ~800 mm(3). Tests to measure serum lipase levels and histological analyses of tumor tissues were also conducted to assess PACC progression and re-differentiation.

Results: The model presented here expresses the same IHC markers found in human PACC. In the chemotherapy study, oxaliplatin produced a prolonged durable growth response associated with increased apoptosis, decreased serum lipase levels and increased healthy acinar cells. Bevacizumab also produced a significant growth response, but the effect was not prolonged as demonstrated by oxaliplatin treatment. The other chemotherapies had moderate to little effect, particularly after treatment ceased. Mutations in DNA repair genes are common in PACC and increase tumor susceptibility to oxaliplatin. To explore this we performed IHC and found no nuclear expression of BRCA2 in our model, indicating a mutation affecting nuclear localization. Gene sequencing confirms BRCA2 has a homozygous gene deletion on Exon 10, which frequently causes a protein truncation.

Conclusions: In summary, we report the development and characterization of the first and only preclinical PACC PDTX model. Here we show sustained anti-tumor activity of single agent oxaliplatin, a compound that is more effective in tumors that harbor mutations in DNA repair genes. Our data shows that BRCA2 is mutated in our PACC model, which could contribute to the oxaliplatin sensitivity observed. Further studies on this rare PACC model can serve to elucidate other novel therapies, biomarkers, and molecular mechanisms of signaling and drug resistance.

No MeSH data available.


Related in: MedlinePlus