Targeting reactive oxygen species in development and progression of pancreatic cancer

Design and Synthesis of Novel Reactive Oxygen Species Inducers for the Treatment of Pancreatic Ductal Adenocarcinoma

Altering redox homeostasis provides distinctive therapeutic opportunities for the treatment of pancreatic cancer. Quinazolinediones (QDs) are novel redox modulators that we previously showed to induce potent growth inhibition in pancreatic ductal adenocarcinoma (PDAC) cell lines. Our lead optimization campaign yielded QD325 as the most potent redox modulator candidate inducing substantial reactive oxygen species (ROS) in PDAC cells. Nascent RNA sequencing following treatments with the QD compounds revealed induction of stress responses in nucleus, endoplasmic reticulum, and mitochondria of pancreatic cancer cells. Furthermore, the QD compounds induced Nrf2-mediated oxidative stress and unfolded protein responses as demonstrated by dose-dependent increases in RNA synthesis of representative genes such as NQO1, HMOX1, DDIT3, and HSPA5. At higher concentrations, the QDs blocked mitochondrial function by inhibiting mtDNA transcription and downregulating the mtDNA-encoded OXPHOS enzymes. Importantly, treatments with QD325 were well tolerated in vivo and significantly delayed tumor growth in mice. Our study supports the development of QD325 as a new therapeutic in the treatment of PDAC.

Ultra-sensitive fluorescent probes for hypochlorite acid detection and exogenous/endogenous imaging of living cells

Two fluorescent probes have been developed to detect HOCl with ultra-high sensitivity and employed to image exogenous/endogenous HOCl in living cells.

Teaching the basics of reactive oxygen species and their relevance to cancer biology: Mitochondrial reactive oxygen species detection, redox signaling, and targeted therapies

Reactive oxygen species (ROS) have been implicated in tumorigenesis (tumor initiation, tumor progression, and metastasis). Of the many cellular sources of ROS generation, the mitochondria and the NADPH oxidase family of enzymes are possibly the most prevalent intracellular sources. In this article, we discuss the methodologies to detect mitochondria-derived superoxide and hydrogen peroxide using conventional probes as well as newly developed assays and probes, and the necessity of characterizing the diagnostic marker products with HPLC and LC-MS in order to rigorously identify the oxidizing species. The redox signaling roles of mitochondrial ROS, mitochondrial thiol peroxidases, and transcription factors in response to mitochondria-targeted drugs are highlighted. ROS generation and ROS detoxification in drug-resistant cancer cells and the relationship to metabolic reprogramming are discussed. Understanding the subtle role of ROS in redox signaling and in tumor proliferation, progression, and metastasis as well as the molecular and cellular mechanisms (e.g., autophagy) could help in the development of combination therapies. The paradoxical aspects of antioxidants in cancer treatment are highlighted in relation to the ROS mechanisms in normal and cancer cells. Finally, the potential uses of newly synthesized exomarker probes for in vivo superoxide and hydrogen peroxide detection and the low-temperature electron paramagnetic resonance technique for monitoring oxidant production in tumor tissues are discussed.

Selenoproteins and Metastasis

Cancer survival is largely impacted by the dissemination of cancer cells from the original tumor site to secondary tissues or organs through metastasis. Targets for antimetastatic therapies have recently become a focus of research, but progress will require a better understanding of the molecular mechanisms driving metastasis. Selenoproteins play important roles in many of the cellular activities underlying metastasis including cell adhesion, matrix degradation and migration, invasion into the blood and extravasation into secondary tissues, and subsequent proliferation into metastatic tumors along with the angiogenesis required for growth. In this review the roles identified for different selenoproteins in these steps and how they may promote or inhibit metastatic cancers is discussed. These roles include selenoenzyme modulation of redox tone and detoxification of reactive oxygen species, calcium homeostasis and unfolded protein responses regulated by endoplasmic reticulum selenoproteins, and the multiple physiological responses influenced by other selenoproteins.

Superoxide Dismutases in Pancreatic Cancer

The incidence of pancreatic cancer is increasing as the population ages but treatment advancements continue to lag far behind. The majority of pancreatic cancer patients have a K-ras oncogene mutation causing a shift in the redox state of the cell, favoring malignant proliferation. This mutation is believed to lead to nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation and superoxide overproduction, generating tumorigenic behavior. Superoxide dismutases (SODs) have been studied for their ability to manage the oxidative state of the cell by dismuting superoxide and inhibiting signals for pancreatic cancer growth. In particular, manganese superoxide dismutase has clearly shown importance in cell cycle regulation and has been found to be abnormally low in pancreatic cancer cells as well as the surrounding stromal tissue. Likewise, extracellular superoxide dismutase expression seems to favor suppression of pancreatic cancer growth. With an increased understanding of the redox behavior of pancreatic cancer and key regulators, new treatments are being developed with specific targets in mind. This review summarizes what is known about superoxide dismutases in pancreatic cancer and the most current treatment strategies to be advanced from this knowledge.

Disulfiram/copper selectively eradicates AML leukemia stem cells in vitro and in vivo by simultaneous induction of ROS-JNK and inhibition of NF-κB and Nrf2

Acute myeloid leukemia (AML) is a heterogeneous malignancy. Despite the advances in past decades, the clinical outcomes of AML patients remain poor. Leukemia stem cells (LSCs) is the major cause of the recurrence of AML even after aggressive treatment making, promoting development of LSC-targeted agents is an urgent clinical need. Although the antitumor activity of disulfiram (DS), an approved anti-alcoholism drug, has been demonstrated in multiple types of tumors including hematological malignancies such as AML, it remains unknown whether this agent would also be able to target cancer stem cells like LSCs. Here, we report the in vitro and in vivo activity of DS in combination with copper (Cu) against CD34⁺/CD38⁺ leukemia stem-like cells sorted from KG1α and Kasumi-1 AML cell lines, as well as primary CD34⁺ AML samples. DS plus Cu (DS/Cu) displayed marked inhibition of proliferation, induction of apoptosis, and suppression of colony formation in cultured AML cells while sparing the normal counterparts. DS/Cu also significantly inhibited the growth of human CD34⁺/CD38⁺ leukemic cell-derived xenografts in NOD/SCID mice. Mechanistically, DS/Cu-induced cytotoxicity was closely associated with activation of the stress-related ROS-JNK pathway as well as simultaneous inactivation of the pro-survival Nrf2 and nuclear factor-κB pathways. In summary, our findings indicate that DS/Cu selectively targets leukemia stem-like cells both in vitro and in vivo, thus suggesting a promising LSC-targeted activity of this repurposed agent for treatment of relapsed and refractory AML.

Mitochondrial and Oxidative Stress-Mediated Activation of Protein Kinase D1 and Its Importance in Pancreatic Cancer

Due to alterations in their metabolic activity and decreased mitochondrial efficiency, cancer cells often show increased generation of reactive oxygen species (ROS), but at the same time, to avoid cytotoxic signaling and to facilitate tumorigenic signaling, have mechanism in place that keep ROS in check. This requires signaling molecules that convey increases in oxidative stress to signal to the nucleus to upregulate antioxidant genes. Protein kinase D1 (PKD1), the serine/threonine kinase, is one of these ROS sensors. In this mini-review, we highlight the mechanisms of how PKD1 is activated in response to oxidative stress, so far known downstream effectors, as well as the importance of PKD1-initiated signaling for development and progression of pancreatic cancer.

A fast-response fluorescent probe for hypochlorous acid detection and its application in exogenous and endogenous HOCl imaging of living cells

A facile fluorescent probe for exogenous and endogenous HOCl detection in living cells.