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Targeting the Acidic Tumor Microenvironment: Unexpected Pro-Neoplastic Effects of Oral NaHCO3 Therapy in Murine Breast Tissue.

ABSTRACT: The acidic tumor microenvironment modifies malignant cell behavior. Here, we study consequences of the microenvironment in breast carcinomas. Beginning at carcinogen-based breast cancer induction, we supply either regular or NaHCO3-containing drinking water to female C57BL/6j mice. We evaluate urine and blood acid-base status, tumor metabolism (microdialysis sampling), and tumor pH (pH-sensitive microelectrodes) in vivo. Based on freshly isolated epithelial organoids from breast carcinomas and normal breast tissue, we assess protein expression (immunoblotting, mass spectrometry), intracellular pH (fluorescence microscopy), and cell proliferation (bromodeoxyuridine incorporation). Oral NaHCO3 therapy increases breast tumor pH in vivo from 6.68 ± 0.04 to 7.04 ± 0.09 and intracellular pH in breast epithelial organoids by ~0.15. Breast tumors develop with median latency of 85.5 ± 8.2 days in NaHCO3-treated mice vs. 82 ± 7.5 days in control mice. Oral NaHCO3 therapy does not affect tumor growth, histopathology or glycolytic metabolism. The capacity for cellular net acid extrusion is increased in NaHCO3-treated mice and correlates negatively with breast tumor latency. Oral NaHCO3 therapy elevates proliferative activity in organoids from breast carcinomas. Changes in protein expression patterns-observed by high-throughput proteomics analyses-between cancer and normal breast tissue and in response to oral NaHCO3 therapy reveal complex influences on metabolism, cytoskeleton, cell-cell and cell-matrix interaction, and cell signaling pathways. We conclude that oral NaHCO3 therapy neutralizes the microenvironment of breast carcinomas, elevates the cellular net acid extrusion capacity, and accelerates proliferation without net effect on breast cancer development or tumor growth. We demonstrate unexpected pro-neoplastic consequences of oral NaHCO3 therapy that in breast tissue cancel out previously reported anti-neoplastic effects.

SUBMITTER: Voss NCS

PROVIDER: S-EPMC7226235 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Targeting the Acidic Tumor Microenvironment: Unexpected Pro-Neoplastic Effects of Oral NaHCO<sub>3</sub> Therapy in Murine Breast Tissue.

Voss Ninna C S NCS Dreyer Thomas T Henningsen Mikkel B MB Vahl Pernille P Honoré Bent B Boedtkjer Ebbe E

Cancers 20200406 4

The acidic tumor microenvironment modifies malignant cell behavior. Here, we study consequences of the microenvironment in breast carcinomas. Beginning at carcinogen-based breast cancer induction, we supply either regular or NaHCO<sub>3</sub>-containing drinking water to female C57BL/6j mice. We evaluate urine and blood acid-base status, tumor metabolism (microdialysis sampling), and tumor pH (pH-sensitive microelectrodes) in vivo. Based on freshly isolated epithelial organoids from breast carci ...[more]

PMID: 32268614

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Project description:BackgroundInefficient T-cell access to the tumor microenvironment (TME) is among the causes of tumor immune-resistance. Previous evidence demonstrated that targeting CXCR4 improves anti-PD-1/PD-L1 efficacy reshaping TME. To evaluate the role of newly developed CXCR4 antagonists (PCT/IB2011/000120/ EP2528936B1/US2013/0079292A1) in potentiating anti-PD-1 efficacy two syngeneic murine models, the MC38 colon cancer and the B16 melanoma-human CXCR4-transduced, were employed.MethodsMice were subcutaneously injected with MC38 (1?×?106) or B16-hCXCR4 (5?×?105). After two weeks, tumors bearing mice were intraperitoneally (ip) treated with murine anti-PD-1 [RMP1-14] (5?mg/kg, twice week for 2?weeks), Pep R (2?mg/kg, 5?days per week for 2?weeks), or both agents. The TME was evaluated through immunohistochemistry and flow-cytometry. In addition, the effects of the human-anti-PD-1 nivolumab and/or Peptide-R54 (Pep R54), were evaluated on human melanoma PES43 cells and xenografts treated.ResultsThe combined treatment, Pep R plus anti-PD-1, reduced the MC38 Relative Tumor Volume (RTV) by 2.67 fold (p?=?0.038) while nor anti-PD-1, neither Pep R significantly impacted on tumor growth. Significant higher number of Granzyme B (GZMB) positive cells was detected in MC38 tumors from mice treated with the combined treatment (p?=?0.016) while anti-PD-1 determined a modest but significant increase of tumor-infiltrating GZMB positive cells (p?=?0.035). Also, a lower number of FoxP3 positive cells was detected (p?=?0.022). In the B16-hCXCR4 tumors, two weeks of combined treatment reduced tumor volume by 2.27 fold while nor anti-PD-1 neither Pep R significantly impacted on tumor growth. A significant higher number of GRZB positive cells was observed in B16-hCXCR4 tumors treated with combined treatment (p?=?0,0015) as compared to anti-PD-1 (p?=?0.028). The combined treatment reduced CXCR4, CXCL12 and PD-L1 expression in MC38 tumors. In addition, flow cytometry on fresh B16-hCXCR4 tumors showed significantly higher Tregs number following anti-PD-1 partially reversed by the combined treatment Pep R and anti-PD-1. Combined treatment determined an increase of CD8/Tregs and CD8/MDSC ratio. To dissect the effect of anti-PD-1 and CXCR4 targeting on PD-1 expressed by human cancer cells, PES43 human melanoma xenograft model was employed. In vitro human anti-PD-1 nivolumab or pembrolizumab (10??M) reduced PES43 cells growth while nivolumab (10??M) inhibited pERK1/2, P38 MAPK, pAKT and p4EBP. PES43 xenograft mice were treated with Pep R54, a newly developed Pep R derivative (AcHN-Arg-Ala-[DCys-Arg- Nal(2')-His-Pen]- COOH), plus nivolumab. After 3?weeks of combined treatment a significant reduction in tumor growth was shown (p?=?0.038). PES43 lung disseminated tumor cells (DTC) were detected in fresh lung tissues as melanoma positive MCSP-APC+ cells. Although not statistically significant, DTC-PES43 cells were reduced in mice lungs treated with combined treatment while nivolumab or Pep R54 did not affect DTC number.ConclusionCombined treatment with the new developed CXCR4 antagonist, Pep R, plus anti-PD-1, reduced tumor-growth in two syngeneic murine models, anti-PD-1 sensitive and resistant, potentiating Granzyme and reducing Foxp3 cells infiltration. In addition, the human specific CXCR4 antagonist, Pep R54, cooperated with nivolumab in inhibiting the growth of the PD-1 expressing human PES43 melanoma xenograft. This evidence sheds light on PD-1 targeting mechanisms and paves the way for CXCR4/PD-1 targeting combination therapy.

Dataset Information

Targeting the Acidic Tumor Microenvironment: Unexpected Pro-Neoplastic Effects of Oral NaHCO3 Therapy in Murine Breast Tissue.

Publications

Targeting the Acidic Tumor Microenvironment: Unexpected Pro-Neoplastic Effects of Oral NaHCO<sub>3</sub> Therapy in Murine Breast Tissue.

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