Investigator
University Of North Carolina At Chapel Hill
PpIX‐enabled fluorescence‐based detection and photodynamic priming of platinum‐resistant ovarian cancer cells under fluid shear stress
AbstractOver 75% percent of ovarian cancer patients are diagnosed with advanced‐stage disease characterized by unresectable intraperitoneal dissemination and the presence of ascites, or excessive fluid build‐up within the abdomen. Conventional treatments include cytoreductive surgery followed by multi‐line platinum and taxane chemotherapy regimens. Despite an initial response to treatment, over 75% of patients with advanced‐stage ovarian cancer will relapse and succumb to platinum‐resistant disease. Recent evidence suggests that fluid shear stress (FSS), which results from the movement of fluid such as ascites, induces epithelial‐to‐mesenchymal transition and confers resistance to carboplatin in ovarian cancer cells. This study demonstrates, for the first time, that FSS‐induced platinum resistance correlates with increased cellular protoporphyrin IX (PpIX), the penultimate downstream product of heme biosynthesis, the production of which can be enhanced using the clinically approved pro‐drug aminolevulinic acid (ALA). These data suggest that, with further investigation, PpIX could serve as a fluorescence‐based biomarker of FSS‐induced platinum resistance. Additionally, this study investigates the efficacy of PpIX‐enabled photodynamic therapy (PDT) and the secretion of extracellular vesicles under static and FSS conditions in Caov‐3 and NIH:OVCAR‐3 cells, two representative cell lines for high‐grade serous ovarian carcinoma (HGSOC), the most lethal form of the disease. FSS induces resistance to ALA‐PpIX‐mediated PDT, along with a significant increase in the number of EVs. Finally, the ability of PpIX‐mediated photodynamic priming (PDP) to enhance carboplatin efficacy under FSS conditions is quantified. These preliminary findings in monolayer cultures necessitate additional studies to determine the feasibility of PpIX as a fluorescence‐based indicator, and mediator of PDP, to target chemoresistance in the context of FSS.
Recovery from chronic PFAS exposure can reverse chemotherapy resistance and mitochondrial alterations in ovarian cancer cells
Per- and polyfluoroalkyl substances (PFAS) are environmental contaminants of global concern that have been associated with a variety of adverse health outcomes, including diminished chemotherapy response. Previous studies in moderately chemosensitive ovarian cancer cells (OVCAR-3) have shown that the induction of chemoresistance from PFAS exposure is duration-dependent, with longer, more human-relevant exposure durations leading to worse outcomes. Mitochondrial content was also altered following chronic PFAS exposure, suggesting mitochondria as contributors to PFAS-induced chemoresistance. Here, chemotherapy response following chronic PFAS exposure in a chemoresistant human ovarian cancer cell line, OVCAR-8, was evaluated. Compared to OVCAR-3 cells, chemotherapy response was unaffected by chronic PFAS exposure in OVCAR-8 cells. As individuals gain awareness of sources of PFAS exposure, and associated harmful effects, actions can be taken to limit exposure using water filtration systems and/or safer alternatives to PFAS-containing consumer goods. Thus, we also explored the ability of PFAS-sensitive OVCAR-3 cells to recover from chronic exposure. Following 6 passages of chronic PFAS exposure, cells were "outgrown" in the absence of PFAS for 7 additional passages and proliferation, chemotherapy response, and mitochondria-related alterations were assessed. Compared to chronically-exposed cells, outgrown cells displayed heightened sensitivity to chemotherapy along with decreased superoxide production and mitochondrial content. Proliferation remained significantly elevated compared to controls, suggesting that not all PFAS-induced effects are abrogated by a recovery period. Together, these findings suggest that ovarian cancer cells differ in their PFAS sensitivities and that mitochondria-related alterations resulting from chronic PFAS exposure can be reversed following a "recovery period", potentially resensitizing cancer cells to chemotherapy.
Photodynamic priming overcomes platinum resistance from short‐term exposure to select perfluoroalkyl substances in endometrial cancer cell lines
AbstractFirst‐line treatment for advanced‐stage or recurrent endometrial cancer consists of platinum‐ and taxane‐based chemotherapy, to which many patients will develop resistance. Determining the factors that contribute to platinum resistance and developing alternate treatment options for patients with advanced‐stage gynecologic malignancies is critical to improving survival outcomes. Recently, we published the first study evaluating the contribution of perfluoroalkyl substances (PFAS) exposure to platinum resistance in endometrial cancer cell lines and found that select PFAS induce carboplatin resistance, potentially by dysregulating mitochondrial function. The present study expands upon those findings by examining the efficacy of photodynamic priming (PDP) in combination with carboplatin to overcome PFAS‐induced platinum resistance. Due to the suspected role of mitochondrial dysfunction in platinum resistance, two clinically approved photosensitizers that, in part, localize to mitochondrial membranes or are synthesized in mitochondria were evaluated: benzoporphyrin derivative (BPD) and aminolevulinic acid‐induced protoporphyrin IX (ALA‐PpIX), respectively. Combination of ALA‐PpIX‐mediated PDP + carboplatin resulted in a greater reduction in survival fraction than the same combination with BPD. While PDP with both photosensitizers reduced mitochondrial membrane potential, the reduction was greater with BPD‐PDP than ALA‐PpIX‐PDP. These findings demonstrate that BPD‐PDP and ALA‐PpIX‐PDP in combination with carboplatin can be used to overcome PFAS‐induced platinum resistance in endometrial cancer cells.
Photodynamic Priming Overcomes Per‐ and Polyfluoroalkyl Substance (PFAS)‐Induced Platinum Resistance in Ovarian Cancer†
AbstractPer‐ and polyfluoroalkyl substances (PFAS) are widespread environmental contaminants linked to adverse outcomes, including for female reproductive biology and related cancers. We recently reported, for the first time, that PFAS induce platinum resistance in ovarian cancer, potentially through altered mitochondrial function. Platinum resistance is a major barrier in the management of ovarian cancer, necessitating complementary therapeutic approaches. Photodynamic therapy (PDT) is a light‐based treatment modality that reverses platinum resistance and synergizes with platinum‐based chemotherapy. The present study is the first to demonstrate the ability of photodynamic priming (PDP), a low‐dose, sub‐cytotoxic variant of PDT, to overcome PFAS‐induced platinum resistance. Comparative studies of PDP efficacy using either benzoporphyrin derivative (BPD) or 5‐aminolevulinic acid‐induced protoporphyrin IX (PpIX) were conducted in two human ovarian cancer cell lines (NIH:OVCAR‐3 and Caov‐3). BPD and PpIX are clinically approved photosensitizers that preferentially localize to, or are partly synthesized in, mitochondria. PDP overcomes carboplatin resistance in PFAS‐exposed ovarian cancer cells, demonstrating the feasibility of this approach to target the deleterious effects of environmental contaminants. Decreased survival fraction in PDP + carboplatin treated cells was accompanied by decreased mitochondrial membrane potential, suggesting that PDP modulates the mitochondrial membrane, reducing membrane potential and re‐sensitizing ovarian cancer cells to carboplatin.
Photochemical Targeting of Mitochondria to Overcome Chemoresistance in Ovarian Cancer†
AbstractOvarian cancer is the most lethal gynecologic malignancy with a stubborn mortality rate of ~65%. The persistent failure of multiline chemotherapy, and significant tumor heterogeneity, has made it challenging to improve outcomes. A target of increasing interest is the mitochondrion because of its essential role in critical cellular functions, and the significance of metabolic adaptation in chemoresistance. This review describes mitochondrial processes, including metabolic reprogramming, mitochondrial transfer and mitochondrial dynamics in ovarian cancer progression and chemoresistance. The effect of malignant ascites, or excess peritoneal fluid, on mitochondrial function is discussed. The role of photodynamic therapy (PDT) in overcoming mitochondria‐mediated resistance is presented. PDT, a photochemistry‐based modality, involves the light‐based activation of a photosensitizer leading to the production of short‐lived reactive molecular species and spatiotemporally confined photodamage to nearby organelles and biological targets. The consequential effects range from subcytotoxic priming of target cells for increased sensitivity to subsequent treatments, such as chemotherapy, to direct cell killing. This review discusses how PDT‐based approaches can address key limitations of current treatments. Specifically, an overview of the mechanisms by which PDT alters mitochondrial function, and a summary of preclinical advancements and clinical PDT experience in ovarian cancer are provided.
Select Per- and Polyfluoroalkyl Substances (PFAS) Induce Resistance to Carboplatin in Ovarian Cancer Cell Lines
Per- and polyfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants associated with adverse reproductive outcomes including reproductive cancers in women. PFAS can alter normal ovarian function, but the effects of PFAS on ovarian cancer progression and therapy response remain understudied. Ovarian cancer is the most lethal gynecologic malignancy, and a major barrier to effective treatment is resistance to platinum-based chemotherapy. Platinum resistance may arise from exposure to external stimuli such as environmental contaminants. This study evaluated PFAS and PFAS mixture exposures to two human ovarian cancer cell lines to evaluate the ability of PFAS exposure to affect survival fraction following treatment with carboplatin. This is the first study to demonstrate that, at sub-cytotoxic concentrations, select PFAS and PFAS mixtures increased survival fraction in ovarian cancer cells following carboplatin treatment, indicative of platinum resistance. A concomitant increase in mitochondrial membrane potential, measured by the JC-1 fluorescent probe, was observed in PFAS-exposed and PFAS + carboplatin-treated cells, suggesting a potential role for altered mitochondrial function that requires further investigation.
Chronic PFAS Exposure Induces Chemotherapy Resistance by Promoting Mitochondria-Related Alterations in Ovarian Cancer Cells.
Resistance to chemotherapy is a major barrier to the effective treatment of ovarian cancer; however, the role of environmental exposures in the onset of chemoresistance remains elusive. Our previous work in ovarian cancer cells suggests that short-term perfluoroalkyl substances (PFAS) exposures induce chemoresistance, potentially by influencing mitochondrial parameters, but little is known about the effects of longer-term exposures, which are more human-relevant. Since mitochondria play critical roles in determining ovarian cancer chemotherapy response, it is also important to understand the role of environmental exposures in modulating mitochondrial function. This study explored how varying durations of PFAS exposure (2-35 days) affect mitochondrial parameters known to drive chemoresistance in human ovarian cancer cell lines. An ovarian cancer cell line (OVCAR-3) that was chronically exposed to PFAS (26-35 days) was generated. Compared to short-term PFAS exposure, chronic PFAS exposures significantly increased resistance to both carboplatin and doxorubicin. Chemotherapy resistance was accompanied by increased mitochondrial superoxide production, alterations in bioenergetics, and elevated mitochondrial content. These findings suggest that PFAS exposure induces chemotherapy resistance in ovarian cancer cells in a duration-dependent manner, worsened by human-relevant chronic exposures, and that mechanisms driving these effects are influenced by the modulation of mitochondrial parameters. Future studies should focus on targeting mechanisms underlying PFAS-induced chemotherapy resistance to improve survival outcomes.
Photodynamic therapy simultaneously induces ferroptosis- and apoptosis-like lipid signatures in ovarian cancer cells
Abstract Resistance to apoptosis-inducing chemotherapy is a major factor contributing to treatment failure and poor survival outcomes in high-grade serous ovarian cancer (HGSOC). Ferroptosis, a regulated form of cell death driven by lipid peroxidation, has emerged as a promising effector mechanism because it remains available in HGSOC cells with impaired apoptosis signaling. While most research has focused on pharmacological ferroptosis inducers, there is growing interest in strategies that could trigger lipid autoxidation through externally delivered energy, such as photons. Photodynamic therapy (PDT), which utilizes light and light-activatable photosensitizers to generate reactive molecular species, offers a means of initiating lipid peroxidation with a high degree of precision and minimal systemic toxicities. However, the precise lipid targets of PDT, the influence of varying tumor lipidomic landscapes, and the role of ferroptosis sensitivity on PDT-lipid interactions have yet to be elucidated. In this study, we systematically compare PDT to ferroptosis induced by the inhibition of glutathione peroxidase 4, focusing on lipid redox states and composition in HGSOC cell lines. While PDT was similarly effective in both ferroptosis-sensitive and -resistant cells, its effects on cellular lipidomes differed markedly. PDT robustly induced lipid radical formation in both cell types; however, a dose-dependent accumulation of lipid hydroxides and hydroperoxides was only observed in ferroptosis-sensitive cells rich in unsaturated phospholipids. Further analysis revealed a significant overlap in lipid oxidation targets between PDT and ferroptosis. Notably, in both cell types, and in vivo, PDT upregulated ceramides, a lipid class strongly associated with mitochondrial apoptosis. In summary, PDT exhibited comparable efficacy in both ferroptosis-sensitive and -resistant cells by triggering a combination of lipid peroxidation and ceramide upregulation, suggesting the activation of both ferroptosis and apoptosis pathways. Further studies are needed to explore the role of PDT-induced lipidomic changes in the initiation of various cell death pathways and in overcoming chemoresistance in HGSOC.
Overcoming the effects of fluid shear stress in ovarian cancer cell lines: Doxorubicin alone or photodynamic priming to target platinum resistance
AbstractResistance to platinum‐based chemotherapies remains a significant challenge in advanced‐stage high‐grade serous ovarian carcinoma, and patients with malignant ascites face the poorest outcomes. It is, therefore, important to understand the effects of ascites, including the associated fluid shear stress (FSS), on phenotypic changes and therapy response, specifically FSS‐induced chemotherapy resistance and the underlying mechanisms in ovarian cancer. This study investigated the effects of FSS on response to cisplatin, a platinum‐based chemotherapy, and doxorubicin, an anthracycline, both of which are commonly used to manage advanced‐stage ovarian cancer. Consistent with prior research, OVCAR‐3 and Caov‐3 cells cultivated under FSS demonstrated significant resistance to cisplatin. Examination of the role of mitochondria revealed an increase in mitochondrial DNA copy number and intracellular ATP content in cultures grown under FSS, suggesting that changes in mitochondria number and metabolic activity may contribute to platinum resistance. Interestingly, no resistance to doxorubicin was observed under FSS, the first such observation of a lack of resistance under these conditions. Finally, this study demonstrated the potential of photodynamic priming using benzoporphyrin derivative, a clinically approved photosensitizer that localizes in part to mitochondria and endoplasmic reticula, to enhance the efficacy of cisplatin, but not doxorubicin, thereby overcoming FSS‐induced platinum resistance.
