Inhibition of acid ceramidase elicits mitochondrial dysfunction and oxidative stress in pancreatic cancer cells

The maintenance of genome integrity and fidelity is vital for the proper function and survival of all organisms. Recent studies have revealed that APE2 is required to activate an ATR-Chk1 DNA damage response (DDR) pathway in response to oxidative stress and a defined DNA single-strand break (SSB) in Xenopus laevis egg extracts. However, it remains unclear whether APE2 is a general regulator of the DDR pathway in mammalian cells. Here, we provide evidence using human pancreatic cancer cells that APE2 is essential for ATR DDR pathway activation in response to different stressful conditions including oxidative stress, DNA replication stress, and DNA double-strand breaks. Fluorescence microscopy analysis shows that APE2-knockdown (KD) leads to enhanced γH2AX foci and increased micronuclei formation. In addition, we identified a small molecule compound Celastrol as an APE2 inhibitor that specifically compromises the binding of APE2 but not RPA to ssDNA and 3′-5′ exonuclease activity of APE2 but not APE1. The impairment of ATR-Chk1 DDR pathway by Celastrol in Xenopus egg extracts and human pancreatic cancer cells highlights the physiological significance of Celastrol in the regulation of APE2 functionalities in genome integrity. Notably, cell viability assays demonstrate that APE2-KD or Celastrol sensitizes pancreatic cancer cells to chemotherapy drugs. Overall, we propose APE2 as a general regulator for the DDR pathway in genome integrity maintenance.

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Abstract 367: Assessing the therapeutic efficacy of Cyst(e)inase to induce oxidative stress mediated cytotoxicity in pancreatic cancer cells

10.1158/1538-7445.am2016-367 ◽

2016 ◽

Author(s):

Sabin Kshattry ◽

Achinto Saha ◽

Shira Cramer ◽

Everett M. Stone ◽

George Georgiou ◽

...

Keyword(s):

Oxidative Stress ◽

Pancreatic Cancer ◽

Cancer Cells ◽

Therapeutic Efficacy ◽

Pancreatic Cancer Cells

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A phase II trial of pharmacological ascorbate, gemcitabine, and nabpaclitaxel for metastatic pancreatic cancer.

Journal of Clinical Oncology ◽

10.1200/jco.2020.38.4_suppl.tps791 ◽

2020 ◽

Vol 38 (4_suppl) ◽

pp. TPS791-TPS791

Author(s):

Pashtoon Murtaza Kasi ◽

Kellie Bodeker ◽

Daniel James Berg ◽

Chandrikha Chandrasekharan ◽

Saima Sharif ◽

...

Keyword(s):

Oxidative Stress ◽

Pancreatic Cancer ◽

Clinical Trial ◽

Cancer Cells ◽

Objective Response ◽

Plasma Concentrations ◽

High Dose ◽

Resectable Pancreatic Cancer ◽

Pancreatic Cancer Cells ◽

Production Of Hydrogen

TPS791 Background: FOLFIRINOX or gemcitabine/nab-paclitaxel are both frontline chemotherapy options for patients with metastatic pancreas cancer. For most who cannot tolerate the triplet, the latter doublet is the preferred option. Through previous work by our group, pharmacologic ascorbate is known to synergize with gemcitabine; preliminary in vitro data from our group suggests a similar synergistic response with paclitaxel. Though ascorbate has been utilized in cancer therapy, few robust trials have investigated intravenous delivery of ascorbate to deliver plasma concentrations that are cytotoxic to tumor cells. Our prior studies have demonstrated ascorbate induces oxidative stress and cytotoxicity in pancreatic cancer cells; this cytotoxicity appears to be greater in tumor vs. normal cells. We hypothesize that production of hydrogen peroxide mediates the increased susceptibility of pancreatic cancer cells to ascorbate-induced metabolic oxidative stress, resulting in improved treatment outcomes, which has led to the development of the clinical trial (NCT02905578). Methods: All participants receive gemcitabine (1000 mg/m2 weekly) and nab-paclitaxel (125 mg/m2) on cycle days 1, 8, and 15 of a 28-day cycle. Participants are randomized to ± pharmacologic ascorbate (75-gram infusion 3x weekly) in addition to chemotherapy. Study therapy continues until tumor progression. The primary objective is to determine overall survival in patients when treated with combination gemcitabine, nab-Paclitaxel and high-dose ascorbic acid compared to gemcitabine and nab-paclitaxel in patients with non-resectable pancreatic cancer. Secondary objectives include determining objective response rate as well as progression free survival using RECIST 1.1 criteria employing a blinded reviewer for RECIST measurements. The study opened to accrual in 2018 with a goal of enrolling 65 participants. Oversight.Study is conducted under IND 105715 (J. Cullen, sponsor). The University of Iowa Biomedical IRB (IRB-01) serves as the IRB of record. Clinical trial information: NCT02905578.

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