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Nuclear basic fibroblast growth factor regulates triple-negative breast cancer chemo-resistance.

Li S, Payne S, Wang F, Claus P, Su Z, Groth J, Geradts J, de Ridder G, Alvarez R, Marcom PK, Pizzo SV, Bachelder RE - Breast Cancer Res. (2015)

Bottom Line: The importance of bFGF for survival of these chemo-residual cells is interrogated using short hairpin knockdown strategies.Adding back a nuclear bFGF construct to bFGF knockdown cells restores their chemo-resistance.Nuclear bFGF-mediated chemo-resistance is associated with increased DNA-dependent protein kinase (DNA-PK) expression and accelerated DNA repair.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Duke University Medical Center, P.O. Box 3712, Durham, N.C., 27710, USA. shenduo.li@duke.edu.

ABSTRACT

Introduction: Chemotherapy remains the only available treatment for triple-negative (TN) breast cancer, and most patients exhibit an incomplete pathologic response. Half of patients exhibiting an incomplete pathologic response die within five years of treatment due to chemo-resistant, recurrent tumor growth. Defining molecules responsible for TN breast cancer chemo-resistance is crucial for developing effective combination therapies blocking tumor recurrence. Historically, chemo-resistance studies have relied on long-term chemotherapy selection models that drive genetic mutations conferring cell survival. Other models suggest that tumors are heterogeneous, being composed of both chemo-sensitive and chemo-resistant tumor cell populations. We previously described a short-term chemotherapy treatment model that enriches for chemo-residual TN tumor cells. In the current work, we use this enrichment strategy to identify a novel determinant of TN breast cancer chemotherapy resistance [a nuclear isoform of basic fibroblast growth factor (bFGF)].

Methods: Studies are conducted using our in vitro model of chemotherapy resistance. Short-term chemotherapy treatment enriches for a chemo-residual TN subpopulation that over time resumes proliferation. By western blotting and real-time polymerase chain reaction, we show that this chemotherapy-enriched tumor cell subpopulation expresses nuclear bFGF. The importance of bFGF for survival of these chemo-residual cells is interrogated using short hairpin knockdown strategies. DNA repair capability is assessed by comet assay. Immunohistochemistry (IHC) is used to determine nuclear bFGF expression in TN breast cancer cases pre- and post- neoadjuvant chemotherapy.

Results: TN tumor cells surviving short-term chemotherapy treatment express increased nuclear bFGF. bFGF knockdown reduces the number of chemo-residual TN tumor cells. Adding back a nuclear bFGF construct to bFGF knockdown cells restores their chemo-resistance. Nuclear bFGF-mediated chemo-resistance is associated with increased DNA-dependent protein kinase (DNA-PK) expression and accelerated DNA repair. In fifty-six percent of matched TN breast cancer cases, percent nuclear bFGF-positive tumor cells either increases or remains the same post- neoadjuvant chemotherapy treatment (compared to pre-treatment). These data indicate that in a subset of TN breast cancers, chemotherapy enriches for nuclear bFGF-expressing tumor cells.

Conclusion: These studies identify nuclear bFGF as a protein in a subset of TN breast cancers that likely contributes to drug resistance following standard chemotherapy treatment.

No MeSH data available.


Related in: MedlinePlus

Nuclear basic fibroblast growth factor (bFGF) expression is increased in a subset of triple-negative (TN) breast cancers post neoadjuvant chemotherapy treatment. bFGF immunohistochemistry was performed on matched tumor tissues obtained from a patient with TN breast cancer before (pre-chemotherapy) and after (post-chemotherapy) neoadjuvant chemotherapy (docetaxel/cyclophosphamide) treatment. Magnification ×200
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Fig8: Nuclear basic fibroblast growth factor (bFGF) expression is increased in a subset of triple-negative (TN) breast cancers post neoadjuvant chemotherapy treatment. bFGF immunohistochemistry was performed on matched tumor tissues obtained from a patient with TN breast cancer before (pre-chemotherapy) and after (post-chemotherapy) neoadjuvant chemotherapy (docetaxel/cyclophosphamide) treatment. Magnification ×200

Mentions: To validate our findings in patients with TN breast cancer, we optimized an immunohistochemistry (IHC) protocol for detecting nuclear and cytosolic bFGF in formalin-fixed, paraffin embedded tissues. In a pilot study, we selected nine patients with TN breast cancer that exhibited an incomplete pathologic response to neoadjuvant chemotherapy treatment. Matched samples from patients with TN breast cancer (Fig. 8), obtained before and after neoadjuvant chemotherapy treatment, were stained with bFGF antibody. As shown in Table 1, in five of nine patients, the percentage of nuclear bFGF+ tumor cells increased or remained the same in the post treatment samples compared to those obtained pre-treatment. In contrast, in four of nine patients with TNBC, the percentage of nuclear bFGF+ tumor cells decreased post treatment. These data demonstrate that nuclear bFGF-positive cells are enriched in a subset of patients with TN breast cancer following neoadjuvant chemotherapy treatment. Of note, the percentage of cytosolic bFGF+ tumor cells did not follow the same trends pre-treatment versus post treatment as did the percentage of nuclear bFGF+ tumor cells for these patients (data not shown).Fig. 8


Nuclear basic fibroblast growth factor regulates triple-negative breast cancer chemo-resistance.

Li S, Payne S, Wang F, Claus P, Su Z, Groth J, Geradts J, de Ridder G, Alvarez R, Marcom PK, Pizzo SV, Bachelder RE - Breast Cancer Res. (2015)

Nuclear basic fibroblast growth factor (bFGF) expression is increased in a subset of triple-negative (TN) breast cancers post neoadjuvant chemotherapy treatment. bFGF immunohistochemistry was performed on matched tumor tissues obtained from a patient with TN breast cancer before (pre-chemotherapy) and after (post-chemotherapy) neoadjuvant chemotherapy (docetaxel/cyclophosphamide) treatment. Magnification ×200
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4491247&req=5

Fig8: Nuclear basic fibroblast growth factor (bFGF) expression is increased in a subset of triple-negative (TN) breast cancers post neoadjuvant chemotherapy treatment. bFGF immunohistochemistry was performed on matched tumor tissues obtained from a patient with TN breast cancer before (pre-chemotherapy) and after (post-chemotherapy) neoadjuvant chemotherapy (docetaxel/cyclophosphamide) treatment. Magnification ×200
Mentions: To validate our findings in patients with TN breast cancer, we optimized an immunohistochemistry (IHC) protocol for detecting nuclear and cytosolic bFGF in formalin-fixed, paraffin embedded tissues. In a pilot study, we selected nine patients with TN breast cancer that exhibited an incomplete pathologic response to neoadjuvant chemotherapy treatment. Matched samples from patients with TN breast cancer (Fig. 8), obtained before and after neoadjuvant chemotherapy treatment, were stained with bFGF antibody. As shown in Table 1, in five of nine patients, the percentage of nuclear bFGF+ tumor cells increased or remained the same in the post treatment samples compared to those obtained pre-treatment. In contrast, in four of nine patients with TNBC, the percentage of nuclear bFGF+ tumor cells decreased post treatment. These data demonstrate that nuclear bFGF-positive cells are enriched in a subset of patients with TN breast cancer following neoadjuvant chemotherapy treatment. Of note, the percentage of cytosolic bFGF+ tumor cells did not follow the same trends pre-treatment versus post treatment as did the percentage of nuclear bFGF+ tumor cells for these patients (data not shown).Fig. 8

Bottom Line: The importance of bFGF for survival of these chemo-residual cells is interrogated using short hairpin knockdown strategies.Adding back a nuclear bFGF construct to bFGF knockdown cells restores their chemo-resistance.Nuclear bFGF-mediated chemo-resistance is associated with increased DNA-dependent protein kinase (DNA-PK) expression and accelerated DNA repair.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Duke University Medical Center, P.O. Box 3712, Durham, N.C., 27710, USA. shenduo.li@duke.edu.

ABSTRACT

Introduction: Chemotherapy remains the only available treatment for triple-negative (TN) breast cancer, and most patients exhibit an incomplete pathologic response. Half of patients exhibiting an incomplete pathologic response die within five years of treatment due to chemo-resistant, recurrent tumor growth. Defining molecules responsible for TN breast cancer chemo-resistance is crucial for developing effective combination therapies blocking tumor recurrence. Historically, chemo-resistance studies have relied on long-term chemotherapy selection models that drive genetic mutations conferring cell survival. Other models suggest that tumors are heterogeneous, being composed of both chemo-sensitive and chemo-resistant tumor cell populations. We previously described a short-term chemotherapy treatment model that enriches for chemo-residual TN tumor cells. In the current work, we use this enrichment strategy to identify a novel determinant of TN breast cancer chemotherapy resistance [a nuclear isoform of basic fibroblast growth factor (bFGF)].

Methods: Studies are conducted using our in vitro model of chemotherapy resistance. Short-term chemotherapy treatment enriches for a chemo-residual TN subpopulation that over time resumes proliferation. By western blotting and real-time polymerase chain reaction, we show that this chemotherapy-enriched tumor cell subpopulation expresses nuclear bFGF. The importance of bFGF for survival of these chemo-residual cells is interrogated using short hairpin knockdown strategies. DNA repair capability is assessed by comet assay. Immunohistochemistry (IHC) is used to determine nuclear bFGF expression in TN breast cancer cases pre- and post- neoadjuvant chemotherapy.

Results: TN tumor cells surviving short-term chemotherapy treatment express increased nuclear bFGF. bFGF knockdown reduces the number of chemo-residual TN tumor cells. Adding back a nuclear bFGF construct to bFGF knockdown cells restores their chemo-resistance. Nuclear bFGF-mediated chemo-resistance is associated with increased DNA-dependent protein kinase (DNA-PK) expression and accelerated DNA repair. In fifty-six percent of matched TN breast cancer cases, percent nuclear bFGF-positive tumor cells either increases or remains the same post- neoadjuvant chemotherapy treatment (compared to pre-treatment). These data indicate that in a subset of TN breast cancers, chemotherapy enriches for nuclear bFGF-expressing tumor cells.

Conclusion: These studies identify nuclear bFGF as a protein in a subset of TN breast cancers that likely contributes to drug resistance following standard chemotherapy treatment.

No MeSH data available.


Related in: MedlinePlus