Cancer Chemoprevention: Preclinical In Vivo Alternate Dosing Strategies to Reduce Drug Toxicities

Aspirin-Fisetin Combinatorial Treatment Exerts Cytotoxic and Anti-Migratory Activities in A375 Malignant Melanoma Cells

Background and Objectives: Malignant melanoma (MM) remains one of the most aggressive cancers worldwide, presenting a limited number of therapeutic options at present. Aspirin (ASA), a broadly used non-steroid anti-inflammatory medicine, has recently emerged as a candidate for repurposing in cancer management, due to its therapeutic potential in the treatment of several neoplasms which include MM. Fisetin (FIS) is a flavonoid phytoestrogen instilled with multispectral pharmacological activities, including a potent anti-melanoma property. The present study aimed to assess the potential improved anti-neoplastic effect resulting from the association of ASA and FIS for MM therapy. Materials and Methods: The study was conducted using the A375 cell line as an experimental model for MM. Cell viability was assessed via the MTT test. Cell morphology and confluence were evaluated using bright-field microscopy. The aspect of cell nuclei and tubulin fibers was observed through immunofluorescence staining. The irritant potential and the anti-angiogenic effect were determined on the chorioallantoic membrane of chicken fertilized eggs. Results: The main findings related herein demonstrated that the ASA 2.5 mM + FIS (5, 10, 15, and 20 µM) combination exerted a higher cytotoxicity in A375 MM cells compared to the individual compounds, which was outlined by the concentration-dependent and massive reduction in cell viability, loss of cell confluence, cell shrinkage and rounding, apoptotic-like nuclear features, constriction and disruption of tubulin filaments, increased apoptotic index, and suppressed migratory ability. ASA 2.5 mM + FIS 20 µM treatment lacked irritant potential on the chorioallantoic membrane and inhibited blood-vessel formation in ovo. Conclusion: These results stand as one of the first contributions presenting the anti-melanoma effect of the ASA + FIS combinatorial treatment.

Genistein-Aspirin Combination Exerts Cytotoxic and Anti-Migratory Effects in Human Colorectal Cancer Cells

Colorectal cancer (CRC) is a heterogenous pathology with high incidence and mortality rates globally, but it is also preventable so finding the most promising candidates (natural compounds or repurposed drugs) to be chemopreventive alternatives has become a topic of interest in recent years. The present work aims to elucidate the potential effects of a combination between genistein (GEN), an isoflavone of natural origin, and aspirin (ASA) in CRC prevention/treatment by performing an in vitro evaluation in human colorectal cancer cells (HCT-116) and an in ovo analysis using the chick embryo chorioallantoic membrane (CAM) model. Cell viability was verified by an MTT (migratory potential by scratch) assay, and the expressions of MMP-2 and MMP-9 were analyzed using RT-qPCR. Our results indicated a dose-dependent cytotoxic effect of ASA (2.5 mM) + GEN (10-75 µM) combination characterized by reduced cell viability and morphological changes (actin skeleton reorganization and nuclei deterioration), an inhibition of HCT-116 cells' migratory potential by down-regulating MMP-2 and MMP-9 mRNA expressions, and an antiangiogenic effect by modifying the vascular network. These promising results raise the possibility of future in-depth investigations regarding the chemopreventive/therapeutical potential of ASA+GEN combination.

Benefits of Natural Antioxidants on Oral Health

In recent years, special attention has been paid to the correlation between oxidation-reduction mechanisms and human health. The free radicals produced via physiological cellular biochemical processes are major contributors to oxidation phenomena. Their instability is the major cause of cellular damage. Free radical reactive oxygen species containing oxygen are the best-known ones. The body neutralises the harmful effects of free radicals via the production of endogenous antioxidants (superoxide dismutase, catalase, glutathione, and melatonin). The field of study of nutraucetics has found antioxidant capacity in substances such as vitamins A, B, C, E, coenzyme Q-10, selenium, flavonoids, lipoic acid, carotenoids, and lycopene contained in some foods. There are several areas of investigation that aim to research the interaction between reactive oxygen species, exogenous antioxidants, and the microbiota to promote increased protection via the peroxidation of macromolecules (proteins, and lipids) by maintaining a dynamic balance among the species that make up the microbiota. In this scoping review, we aim to map the scientific literature on oxidative stress related to the oral microbiota, and the use of natural antioxidants to counteract it, to assess the volume, nature, characteristics, and type of studies available to date, and to suggest the possible gaps that will emerge from the analysis.

Natural Products as Cancer Chemo Preventive Agents: Where We Stand

This work briefly reviews cancer chemoprevention. This is a very challenging field, as products with a high level of toxicity such as chemotherapeutic agents may be proposed and accepted only under life-threatening conditions. Cancer chemoprevention is otherwise limited to completely safe substances, preferably having neither toxic nor side effects, administered in relatively low amounts. Phases of clinical trials, therapeutic end-points, and biomarkers of chemoprevention are difficult to be defined. The clinical trials needed to prove the efficacy of chemopreventive agents must be very long and extremely widespread to achieve significance, with many variables difficult to control, and therefore subjected to many confounding factors. This makes them almost impossible. It is, therefore, no surprise, if the progress of chemoprevention has been so far very limited. There are only a few examples of direct use of chemopreventive agents, under investigation, but with anything but established protocols, in addition to indirect uses such as general supplementation with antioxidant, anti-inflammatory, and immune-supportive agents. Cancer chemoprevention remains a potentially very rewarding approach, certainly worth further study, but extremely difficult to pursue, in need of different methodological approaches to producing valuable chemopreventive compounds of clear dosages and benefits.

Cloperastine inhibits esophageal squamous cell carcinoma proliferation in vivo and in vitro by suppressing mitochondrial oxidative phosphorylation

Esophageal squamous cell carcinoma (ESCC) is a major type of esophageal cancer. The prognosis of patients with ESCC remains poor because of the high morbidity and mortality of the disease. One strategy for drug discovery for ESCC treatment or prevention is screening FDA-approved drugs. In the present study, we found that the antitussive agent cloperastine can inhibit the proliferation of ESCC cells. However, the underlying mechanism was unclear. To determine the mechanism of this inhibitory effect, we performed proteomic analysis using KYSE150 cells treated with cloperastine and DMSO. The results identified several down-regulated signaling pathways included those of three key proteins (NADH dehydrogenase [ubiquinone] 1 alpha subcomplex 1, NADH ubiquinone oxidoreductase subunit S5, and cytochrome C oxidase subunit 6B1) involved in oxidative phosphorylation. Meanwhile, we observed that oxidative phosphorylation in mitochondria was inhibited by the drug. Importantly, cloperastine suppressed ESCC growth in a xenograft mouse model in vivo. Our findings revealed that cloperastine inhibits the proliferation of ESCC in vivo and in vitro by suppressing mitochondrial oxidative phosphorylation.

Meeting Report: Translational Advances in Cancer Prevention Agent Development Meeting

The Division of Cancer Prevention of the National Cancer Institute (NCI) and the Office of Disease Prevention of the National Institutes of Health co-sponsored the Translational Advances in Cancer Prevention Agent Development Meeting on August 27 to 28, 2020. The goals of this meeting were to foster the exchange of ideas and stimulate new collaborative interactions among leading cancer prevention researchers from basic and clinical research; highlight new and emerging trends in immunoprevention and chemoprevention as well as new information from clinical trials; and provide information to the extramural research community on the significant resources available from the NCI to promote prevention agent development and rapid translation to clinical trials. The meeting included two plenary talks and five sessions covering the range from pre-clinical studies with chemo/immunopreventive agents to ongoing cancer prevention clinical trials. In addition, two NCI informational sessions describing contract resources for the preclinical agent development and cooperative grants for the Cancer Prevention Clinical Trials Network were also presented.

Cancer Immunoprevention: Challenges and Potential Opportunities for Use of Immune Checkpoint Inhibitors

Cancer immunoprevention is achieved through promoting antitumor immune surveillance to block tumor formation and progression. Following the success of prophylactic vaccines against human papillomavirus (HPV) in preventing HPV-associated cancer, immunopreventive cancer vaccines targeting tumor antigens have been increasingly evaluated against cancers of noninfectious origin. While advances in cancer immunotherapy with immune checkpoint inhibitors (ICI) have clearly shown that the host immune system can mount effective antitumor immunity against tumor antigens when immune checkpoints are optimally blocked, the use of ICIs in the prevention setting has not been widely explored because of concerns of ICI-associated adverse events. In this issue of Cancer Prevention Research, Chung and colleagues demonstrate that the human cirrhotic liver harbors neoantigens, which accumulate further as the disease progresses to hepatocellular carcinoma (HCC), suggesting that cirrhotic liver may be susceptible to ICI therapy. Utilizing an established mouse model of carcinogen-induced liver fibrosis and HCC, they show that intermittent intervention by ICI, anti-mouse PD-1 (CD279) antibody, can prevent the progression of the precancerous stage of cirrhosis to HCC accompanied by increased T-cell infiltrates in the liver parenchyma. Importantly, there were no overt ICI-associated toxicities in the treated mice, indicating that safe dosing regimens could be established. This work is both significant and timely, opening the door to future studies, where the utility of ICI therapy can be further investigated not only in cirrhosis but other high-risk precancerous conditions. In this perspective, we discuss the implications of their findings, and the challenges and potential opportunities for use of ICIs for cancer immunoprevention.See related article by Chung et al., p. 911.

Combination of Erlotinib and Naproxen Employing Pulsatile or Intermittent Dosing Profoundly Inhibits Urinary Bladder Cancers

Daily dosing of either NSAIDs or EGFR inhibitors has been shown to prevent bladder cancer development in a N-butyl-(4-hydroxybutyl)nitrosamine (OH-BBN)-induced rat model. However, these inhibitors cause gastrointestinal ulceration and acneiform rash, respectively, limiting their continuous use in a clinical prevention setting. We studied chemopreventive efficacy of pulsatile dosing of EGFR inhibitor erlotinib (42 mg/kg BW, once/week) combined with intermittent or continuous low doses of the NSAID naproxen (30 mg/kg BW/day, 3 weeks on/off or 128 ppm daily in diet) in the OH-BBN induced rat bladder cancer model. The interventions were started either at 1 or 4 weeks (early intervention) or 3 months (delayed intervention) after the last OH-BBN treatment, by which time the rats had developed microscopic bladder lesions. All combination regimens tested as early versus late intervention led to the reduction of the average bladder tumor weights (54%-82%; P < 0.01 to P < 0.0001), a decrease in tumor multiplicity (65%-85%; P < 0.01 to P < 0.0001), and a decrease in the number of rats with large palpable tumors (>200 mg; 83%-90%; P < 0.01 to P < 0.0001). Levels of signal transduction markers, Ki-67, cyclin D1, IL1β, pSTAT3, and pERK, were significantly (P < 0.05 to P < 0.001) reduced in the treated tumors, demonstrating their potential utility as predictive markers for efficacy. These findings demonstrate that significant chemopreventive efficacy could be achieved with alternative intervention regimens designed to reduce the toxicity of agents, and that starting erlotinib and/or naproxen treatments at the time microscopic tumors were present still conferred the efficacy.

Broccoli or Sulforaphane: Is It the Source or Dose That Matters?

There is robust epidemiological evidence for the beneficial effects of broccoli consumption on health, many of them clearly mediated by the isothiocyanate sulforaphane. Present in the plant as its precursor, glucoraphanin, sulforaphane is formed through the actions of myrosinase, a β-thioglucosidase present in either the plant tissue or the mammalian microbiome. Since first isolated from broccoli and demonstrated to have cancer chemoprotective properties in rats in the early 1990s, over 3000 publications have described its efficacy in rodent disease models, underlying mechanisms of action or, to date, over 50 clinical trials examining pharmacokinetics, pharmacodynamics and disease mitigation. This review evaluates the current state of knowledge regarding the relationships between formulation (e.g., plants, sprouts, beverages, supplements), bioavailability and efficacy, and the doses of glucoraphanin and/or sulforaphane that have been used in pre-clinical and clinical studies. We pay special attention to the challenges for better integration of animal model and clinical studies, particularly with regard to selection of dose and route of administration. More effort is required to elucidate underlying mechanisms of action and to develop and validate biomarkers of pharmacodynamic action in humans. A sobering lesson is that changes in approach will be required to implement a public health paradigm for dispensing benefit across all spectrums of the global population.