Anticancer activity and mechanism of action of retinoids in oral and pharyngeal cancer

Genomic Engineering of Oral Keratinocytes to Establish In Vitro Oral Potentially Malignant Disease Models as a Platform for Treatment Investigation

Precancerous cells in the oral cavity may appear as oral potentially malignant disorders, but they may also present as dysplasia without visual manifestation in tumor-adjacent tissue. As it is currently not possible to prevent the malignant transformation of these oral precancers, new treatments are urgently awaited. Here, we generated precancer culture models using a previously established method for the generation of oral keratinocyte cultures and incorporated CRISPR/Cas9 editing. The generated cell lines were used to investigate the efficacy of a set of small molecule inhibitors. Tumor-adjacent mucosa and oral leukoplakia biopsies were cultured and genetically characterized. Mutations were introduced in CDKN2A and TP53 using CRISPR/Cas9 and combined with the ectopic activation of telomerase to generate cell lines with prolonged proliferation. The method was tested in normal oral keratinocytes and tumor-adjacent biopsies and subsequently applied to a large set of oral leukoplakia biopsies. Finally, a subset of the immortalized cell lines was used to assess the efficacy of a set of small molecule inhibitors. Culturing and genomic engineering was highly efficient for normal and tumor-adjacent oral keratinocytes, but success rates in oral leukoplakia were remarkably low. Knock-out of CDKN2A in combination with either the activation of telomerase or knock-out of TP53 seemed a prerequisite for immortalization. Prolonged culturing was accompanied by additional genetic aberrations in these cultures. The generated cell lines were more sensitive than normal keratinocytes to small molecule inhibitors of previously identified targets. In conclusion, while very effective for normal keratinocytes and tumor-adjacent biopsies, the success rate of oral leukoplakia cell culturing methods was very low. Genomic engineering enabled the prolonged culturing of OL-derived keratinocytes but was associated with acquired genetic changes. Further studies are required to assess to what extent the immortalized cultures faithfully represent characteristics of the cells in vivo.

Update on the Management of Ocular Surface Squamous Neoplasia

Purpose of review

To review and update the latest findings in diagnosis and management of ocular surface squamous neoplasia (OSSN).

Recent findings

OSSN is the most common anterior segment neoplastic disease process. Several ocular surface imaging techniques have been developed for the early diagnosis and management of clinical and subclinical ocular surface squamous neoplasia, including high-resolution optical coherence tomography (HR-OCT), in vivo confocal microscopy, and ultrasound biomicroscopy. Treatment modalities include both surgical and medical management, with a recent trend towards primary and adjunctive pharmacotherapy.

Summary

There is increasing use of HR-OCT for the diagnosis and monitoring of clinical and subclinical OSSN lesions. Topical pharmacotherapy agents, including interferon α-2b, 5-fluorouracil, and mitomycin C, have demonstrable efficacy in the treatment of OSSN and their use may be dictated based upon tumor factors, patient factors, cost, and side effect profile. Both surgical excision and adjunctive topical medications have excellent success, with the favored treatment method trending towards topical pharmacotherapy as primary therapy.

Mechanistic aspects of carotenoid health benefits - where are we now?

Dietary intake and tissue levels of carotenoids have been associated with a reduced risk of several chronic diseases, including cardiovascular diseases, type 2 diabetes, obesity, brain-related diseases and some types of cancer. However, intervention trials with isolated carotenoid supplements have mostly failed to confirm the postulated health benefits. It has thereby been speculated that dosing, matrix and synergistic effects, as well as underlying health and the individual nutritional status plus genetic background do play a role. It appears that our knowledge on carotenoid-mediated health benefits may still be incomplete, as the underlying mechanisms of action are poorly understood in relation to human relevance. Antioxidant mechanisms - direct or via transcription factors such as NRF2 and NF-κB - and activation of nuclear hormone receptor pathways such as of RAR, RXR or also PPARs, via carotenoid metabolites, are the basic principles which we try to connect with carotenoid-transmitted health benefits as exemplified with described common diseases including obesity/diabetes and cancer. Depending on the targeted diseases, single or multiple mechanisms of actions may play a role. In this review and position paper, we try to highlight our present knowledge on carotenoid metabolism and mechanisms translatable into health benefits related to several chronic diseases.

Ameliorative effect of alpha lipoic acid and royal jelly against the side effects of cyclophosphamide in liver of albino rats

Background

Cyclophosphamide (CP) is a cytotoxic anticancer drug used for the treatment of neoplastic diseases. The present study aimed to examine biochemical, histological, and ultrastructural effects of CP on rat liver and determine the hepatoprotective effects of alpha-lipoic acid (LA) or royal jelly (RJ) against CP.

Results

The present study revealed that CP-induced significant increase in hepatic marker enzymes (ALT and AST), and elevation in malonaldehyde (MDA) was concomitant with a significant decrease of superoxide dismutase (SOD). It caused histopathological changes in the liver of rat including vacuolation, infiltration, degeneration, and necrosis. Ultrastructurally, the hepatocytes appeared degenerated with multiple small- and medium-sized lipid droplets in the cytoplasm. Kupffer cell showed a shrunken nucleus. Administration of LA and RJ resulted in an obvious improvement in the altered level of ALT, AST, MDA, and SOD activities when compared with the CP-treated group in addition to marked amelioration in histopathology and ultrastructure of the liver.

Conclusions

LA is markedly effective than RJ in protecting rats against CP-induced biochemical, histopathological, and ultrastructural changes. This protection may be due to its antioxidant properties and scavenging abilities against active free radicals.

Progress in Drug and Formulation Development for the Chemoprevention of Oral Squamous Cell Carcinoma: A Review

BACKGROUND

Cancer is a life-threatening global problem with high incidence rates. Prioritizing the prevention of cancer, chemopreventive agents have drawn much attention from the researchers.

OBJECTIVE

This review focuses on the discussion of the progress in the development of chemopreventive agents and formulations related to the prevention of oral cancer.

METHODS

In this perspective, an extensive literature survey was carried out to understand the mechanism, control and chemoprevention of oral cancer. Different patented agents and formulations have also exhibited cancer preventive efficacy in experimental studies. This review summarizes the etiology of oral cancer and developments in prevention strategies.

RESULTS

The growth of oral cancer is a multistep activity necessitating the accumulation of genetic as well as epigenetic alterations in key regulatory genes. Many risk factors are associated with oral cancer. Genomic technique for sequencing all tumor specimens has been made available to help detect mutations. The recent development of molecular pathway and genetic tools has made the process of diagnosis easier, better forecast and efficient therapeutic management. Different chemical agents have been studied for their efficacy to prevent oral cancer and some of them have shown promising results.

CONCLUSION

Use of chemopreventive agents, either synthetic or natural origin, to prevent carcinogenesis is a worthy concept in the management of cancers. Preventive measures are helpful in controlling the occurrence or severity of the disease. The demonstrated results of preventive agents have opened an arena for the development of promising chemopreventive agents in the management of oral squamous cell carcinoma.

Update on pharmacotherapy for ocular surface squamous neoplasia

The most frequently encountered non-pigmented tumor of the ocular surface is ocular surface squamous neoplasia (OSSN). Over the past two decades, the pharmacological management of OSSN has grown, with topical 5-fluorouracil, mitomycin, and interferon alpha 2b all being successfully used to treat this disease. Other agents, such as anti-vascular endothelial growth factor (VEGF), retinoic acid, cidofovir and Aloe vera, have less frequently been used in the treatment of OSSN. This review will discuss these pharmacologic agents, summarizing available data and presenting the approach to the treatment of these tumors.

A phase III skin cancer chemoprevention study of DFMO: long-term follow-up of skin cancer events and toxicity

Decreasing the incidence of nonmelanoma skin cancer (NMSC) is of great importance in regards to future healthcare services. Given the previously reported preventive effects of α-difluoromethylornithine (DFMO) in skin and colon cancer trials, we determined appropriate cause to update the clinical data on the subjects from the recently reported randomized, double-blind, placebo-controlled phase III skin cancer prevention study of DFMO. Our intention was to retrospectively assess the further incidence of skin cancer, other malignancies, and adverse events of patients accrued to our phase III skin cancer prevention study of DFMO. Clinical records of 209 University of Wisconsin (UW) Health subjects were reviewed, and 2,092.7 person years of on study (884.3 person years) and poststudy (1,208.4 person years) follow-up for these patients were assessed for new NMSC events and recurrence rates from the on study period, the poststudy period, and the two study periods combined. No evidence of increased significant diagnoses or serious adverse events was observed in the DFMO participants. The initially observed, marginally significant reduction (P = 0.069) in NMSC rates for DFMO subjects relative to placebo continued without evidence of rebound. Event rates after discontinuation from study for total NMSCs (DFMO 0.236 NMSC/person/year, placebo 0.297, P = 0.48) or the subtypes of basal cell carcinomas (BCC; DFMO 0.179 BCC/person/year, placebo 0.190, P = 0.77) and squamous cell carcinomas (SCC; DFMO 0.057 SCC/person/year, placebo 0.107, P = 0.43) are listed. Follow-up data revealed a persistent but insignificant reduction in new NMSCs occurring in DFMO subjects without evidence of latent or cumulative toxicity relative to placebo subjects.

Retinoids in biological control and cancer

More than 80 years ago, Wolbach and Howe provided the first evidence suggesting a link between alterations within human cells that lead to malignancies and vitamin A deficiencies (Wolbach and Howe 1925 Nutr. Rev. 36: 16-19). Since that time, epidemiological, preclinical and clinical studies have established a causative relationship between vitamin A deficiency and cancer. Laboratory research has provided insight into the intracellular targets, various signaling cascades and physiological effects of the biologically-active natural and synthetic derivatives of vitamin A, known as retinoids. Collectively, this body of research supports the concept of retinoids as chemopreventive and chemotherapeutic agents that can prevent epithelial cell tumorigenesis by directing the cells to either differentiate, growth arrest, or undergo apoptosis, thus preventing or reversing neoplasia. Continued refinement of the retinoid signaling pathway is essential to establishing their use as effective therapeutics for tumor subtypes whose oncogenic intracellular signaling pathways can be blocked or reversed by treatment with retinoids.

Vitamins A and E: metabolism, roles and transfer to offspring

Vitamins A and E are essential, naturally occurring, fat-soluble nutrients that are involved in several important biological processes such as immunity, protection against tissue damage, reproduction, growth and development. They are extremely important during the early stages of life and must be transferred adequately to the young during gestation and lactation. The present article presents an overview of their biological functions, metabolism and dynamics of transfer to offspring in mammals. Among other topics, the review focuses on the biochemical aspects of their intestinal absorption, blood transport, tissue uptake, storage and catabolism. It also describes their different roles as well as their use as preventive and therapeutic agents. Finally, the mechanisms involved in their transfer during gestation and lactation are discussed.

Temporal Variation and Identification of Factors Associated with Endogenous Retinoic Acid Isomers in Serum from Brazilian Women

Objective: Retinoids (natural and synthetic derivatives of vitamin A) have cancer chemotherapeutic and chemopreventive activities. Retinoic acid (RA) treatment has been associated with significant regression of preneoplastic lesions. However, serious toxicity associated with some therapies has made long-term chemoprevention in healthy populations unfeasible. Recently, serum RA has been shown to increase in response to oral retinol (vitamin A) supplementation. Here, we assess the variability of circulating RA levels and the lifestyle, demographic, and nutritional factors that explain such variability.

Method: Total RA concentration and the concentrations of RA isomers (all-trans-RA, 13-cis-RA, and 9-cis-RA) were measured by high-pressure liquid chromatography in serum samples obtained 4 months apart from 502 women participating in the Ludwig-McGill Cohort (São Paulo, Brazil).

Results: The relative abundance of the three RA isomers was similar for each visit (baseline and month 4), with 13-cis-RA having the highest concentrations followed by 9-cis-RA and all-trans-RA. The within-person variability of total RA and individual isomers was low. Using multivariate logistic regression models (upper tertile versus low/middle tertile of serum RA), we found that age, race, oral contraceptive use, total number of pregnancies, and season of initial blood draw were significantly associated with at least one endogenous RA isomer level. All endogenous RA isomers were positively associated with serum retinol, β-carotene, and β-cryptoxanthin levels.

Conclusion: These results have implications for the design of future epidemiologic studies focused on assessing RA-disease association and intervention studies aimed at modulating RA levels.

Induction of apoptosis in oral cancer cells: agents and mechanisms for potential therapy and prevention

Oral cancer is one of the most disfiguring types of cancer, since the surgical removal of the tumor may result in facial distortion. Oral cancer is also known to exhibit "field cancerization", resulting in the development of a second primary tumor. Furthermore, the five-year survival rate of this disease has remained approximately 50% during the past 30 years. Prevention and early detection/treatment of oral cancer could significantly improve the quality of life for individuals at risk. Recently, the targeted elimination of oral squamous cell carcinoma cells by inducing apoptosis has emerged as a valued strategy to combat oral cancer. Studies utilizing a variety of chemical or biological interventions demonstrated promising results for induction of apoptosis in oral malignant cells. This review summarizes the results of a number of investigations focused specifically on induction of apoptosis in oral cancer cells by synthetic compounds and naturally occurring chemopreventive agents with apoptotic potential.

A comparison of the effectiveness of soy protein isolate and fish oil for reducing the severity of retinoid-induced hypertriglyceridemia

The effectiveness of soy protein isolate (SPI) to reduce the severity of retinoid-induced hypertriglyceridemia has been demonstrated in the rat, but not in human subjects. Because fish oil has been demonstrated to be effective at lowering serum triglyceride concentration in human subjects undergoing retinoid therapy, a study was conducted to compare the ability of SPI with that of fish oil to reduce the severity of retinoid-induced hypertriglyceridemia in the rat. Male Fischer 344 rats, n=8/group, were fed one of four isonitrogenous, isoenergetic diets, consisting of a control diet containing 24% casein +20% corn oil (C), and three 13-cis retinoic acid (13cRA)-supplemented diets containing 24% casein +20% corn oil (R), 24% SPI +20% corn oil (SR), and 24% casein +15% fish oil and 5% corn oil (FR). There was no effect of diet on food intake or final body weight. Serum triglyceride concentration for group R was higher (P<0.001) than for groups C, SR, and FR (7.20 vs. 2.50, 2.84, and 2.02 mmol/L, respectively); values for groups SR and FR did not differ for this parameter. The serum concentration of 13cRA for group R did not differ from that for groups SR and FR. Thus, SPI was as effective as fish oil in reducing the severity of retinoid-induced hypertriglyceridemia in an animal model, suggesting that it may be effective for this purpose in human subjects.

The effectiveness of community-based visual screening and utility of adjunctive diagnostic aids in the early detection of oral cancer

A systematic review of community-based oral cancer screening programmes published between 1966 and March 2002 was undertaken. Data relating to study design, sampling and characteristics of the study group, interventions, and reported outcomes and diagnostic value of visual screening or adjunctive diagnostic aids were abstracted from 36 articles meeting inclusion and exclusion criteria. From these reports, there is insufficient evidence to demonstrate the effectiveness of community-based oral cancer visual screening in enhancing the early detection of oral cancer, due to small effect size. While the evidence is fair to support use of toluidine blue as an aid in diagnosis of oral cancer, there is insufficient evidence to determine whether the use of this or other adjunctive techniques will increase the detection of oral malignancies in community screening programmes. Targeted clinical examination of high-risk individuals may be more effective than mass screening in facilitating early detection of oral cancers.

Carcinogenesis and cyclooxygenase: the potential role of COX-2 inhibition in upper aerodigestive tract cancer

Cyclooxygenase-2 (COX-2) is upregulated in a number of epithelial cancers, including in upper aerodigestive tract (UADT) premalignant and malignant lesions. The purpose of this review is to provide a comprehensive examination of the potential of COX-2 inhibition in prevention of UADT premalignant and malignant disease. A Medline and Cancerlit literature search was conducted for the period 1993-2002, and identified literature was reviewed. There is evidence from in vitro studies, as well as animal models, that inhibition of COX-2 may suppress carcinogenesis by affecting a number of pathways of carcinogenesis, promoting apoptosis and inhibiting angiogenesis. Preliminary studies of gastro-intestinal (GI) carcinogenesis suggest that COX-2 inhibitors may represent an approach to the chemoprevention of epithelial cancers. COX-2 inhibitors may have a potential role in chemoprevention of UADT cancer, and clinical trials appear warranted.