13-cis-retinoic acid in the treatment of oral leukoplakia

A comparative evaluation: Oral leukoplakia surgical management using diode laser, CO2 laser, and cryosurgery

Background

The comparatively evaluate the three surgical treatment modalities namely cryosurgery, diode and CO2 laser surgery in terms of healing outcomes on the day of surgery, first and second week post operatively and recurrence at the end of 18 months was assessed.

Material and Methods

Thirty selected patients were divided randomly into three groups. Each group comprising of ten patients were subjected to one of the three modalities of treatment namely cryosurgery, diode laser or CO2 laser surgery for ablation of OL. Obtained data was analyzed using mainly using Chi-square and Anova tests.

Results

Study showed statistical significant differences (p > 0.05) for evaluation parameters like pain, edema and scar. The parameters like infection, recurrence, bleeding showed no statistical significance. Pain was significantly higher in CO2 laser surgery group as compared with diode laser group. There was no recurrence observed at the end of the 6 months follow up period in all the three study groups.

Conclusions

Observations from the study highlights that all three surgical modalities used in this study were effective for treatment of OL, and the overall summation of the results of the study showed that laser therapy (CO2 and Diode) seems to offer better clinically significant results than cryotherapy.

Key words:Oral premalignant lesion, leukoplakia, cryosurgery, CO2 laser surgery, diode laser surgery.

Safety and Preclinical Efficacy of Aerosol Pioglitazone on Lung Adenoma Prevention in A/J Mice

Pioglitazone is a PPARγ agonist commonly prescribed for the clinical treatment of diabetes. We sought to expand its use to lung cancer prevention in a benzo[a]pyrene (B[a]P) mouse model with direct lung delivery via inhalation. Initially, we conducted inhalational toxicity experiments with 0, 15, 50, 150, and 450 μg/kg body weight/day pioglitazone in 40 A/J mice. We examined the animals for any physical toxicity and bronchoalveolar lavage fluids for inflammatory and cytotoxicity markers. Doses up to and including 450 μg/kg bw/d failed to demonstrate toxicity with aerosol pioglitazone. For chemoprevention experiments, A/J mice were randomized to treatment groups of inhaled doses of 0, 50, 150, or 450 μg/kg bw/d pioglitazone 1 or 8 weeks after the last dose of B[a]P. For the early treatment group, we found up to 32% decrease in lung adenoma formation with 450 μg/kg bw/d pioglitazone. We repeated the treatments in a second late-stage experiment and found up to 44% decreases in lung adenoma formation in doses of pioglitazone of 150 and 450 μg/kg bw/day. Both the early- and the late-stage experiments demonstrated biologically relevant and statistically significant decreases in adenoma formation. We conclude that aerosol pioglitazone is well-tolerated in the A/J mouse model and a promising chemoprevention agent for the lower respiratory tract. Cancer Prev Res; 10(2); 124-32. ©2016 AACR.

The Molecular Biology of Mucosal Field Cancerization of the Head and Neck

Field cancerization was first described in 1953 as histologically altered epithelium surrounding tumor samples taken from the upper aerodigestive tract. Since then, the term has been used to describe multiple patches of pre-malignant disease, a higher-than-expected prevalence of multiple local second primary tumors, and the presence of synchronous distant tumors within the upper aerodigestive tract. Molecular techniques such as karyotype analysis, microsatellite analysis, p53 mutation screening, and X-chromosome inactivation studies have further refined the relationship among these lesions. While there are differences in the techniques used to identify the clonal origins of the lesions, these studies indicate that there is often lateral clonal spread of pre-malignant or malignant disease, and a significant portion of local second primary tumors are in fact genetically related. Distant second primary tumors found in the esophagus are often not related to concurrent head and neck cancer, whereas synchronous squamous lung tumors with a head and neck primary are often, in fact, metastases, rather than independently arising malignancies. These observations help to explain the high incidence of recurrent disease, despite excision or other therapy—pre-malignant or malignant clones often have the ability to migrate and persist outside of the field of treatment. Therefore, alternative means of prevention or therapy that can affect the entire head and neck region may be of benefit to such patients. Future studies will further refine the relationship among these lesions and perhaps identify key molecular alterations to be used as targets for gene therapy.

Integrative Medicine in Head and Neck Cancer

Objective Complementary and alternative medicine, or integrative medicine, has become increasingly popular among patients with head and neck cancer. Despite its increasing prevalence, many patients feel uncomfortable discussing such therapies with their physicians, and many physicians are unaware and underequipped to evaluate or discuss their use with patients. The aim of this article is to use recent data to outline the decision making inherent to integrative medicine utilization among patients with head and neck cancer, to discuss the ethical implications inherent to balancing integrative and conventional approaches to treatment, and to highlight available resources to enhance head and neck cancer providers' understanding of integrative medicine. Data Sources Randomized controlled trials involving integrative medicine or complementary and alternative medicine treatment for cancer patients. Review Methods Trials were drawn from a systematic PubMed database search categorized into cancer prevention, treatment, and symptom management. Conclusions Integrative medicine is gaining popularity for the management of cancer and is most commonly used for symptom management. A number of randomized controlled trials provide data to support integrative therapies, yet physicians who treat head and neck cancer may be faced with ethical dilemmas and practical barriers surrounding incorporation of integrative medicine. Implications for Practice In the management of head and neck cancer, there is an increasing demand for awareness of, dialogue about, and research evaluating integrative medicine therapies. It is important for otolaryngologists to become aware of integrative therapy options, their risks and benefits, and resources for further information to effectively counsel their patients.

Interventions for treating oral leukoplakia to prevent oral cancer

BACKGROUND

Oral leukoplakia is a relatively common oral lesion that, in a small proportion of people, precedes the development of oral cancer. Most leukoplakias are asymptomatic; therefore, the primary objective of treatment should be to prevent onset of cancer. This review updates our previous review, published in 2006.

OBJECTIVES

To assess the effectiveness, safety and acceptability of treatments for leukoplakia in preventing oral cancer.

SEARCH METHODS

We searched the following electronic databases: Cochrane Oral Health's Trials Register (to 16 May 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2016, Issue 4), MEDLINE Ovid (1946 to 16 May 2016), Embase Ovid (1980 to 16 May 2016) and CancerLit via PubMed (1950 to 16 May 2016). We searched the metaRegister of Controlled Trials (to 10 February 2015), ClinicalTrials.gov (to 16 May 2016) and the World Health Organization (WHO) International Clinical Trials Registry Platform for ongoing trials (to 16 May 2016). We placed no restrictions on the language or date of publication when searching electronic databases.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that enrolled people with a diagnosis of oral leukoplakia and compared any treatment versus placebo or no treatment.

DATA COLLECTION AND ANALYSIS

We collected data using a data extraction form. Oral cancer development, demonstrated by histopathological examination, was our primary outcome. Secondary outcomes were clinical resolution of the lesion, improvement of histological features and adverse events. We contacted trial authors for further details when information was unclear. When valid and relevant data were available, we conducted a meta-analysis of the data using a fixed-effect model when we identified fewer than four studies with no heterogeneity. For dichotomous outcomes, we calculated risk ratios (RRs) and 95% confidence intervals (CIs). We assessed risk of bias in studies by using the Cochrane tool. We assessed the overall quality of the evidence by using standardised criteria (Grades of Recommendation, Assessment, Development and Evaluation Working Group (GRADE)).

MAIN RESULTS

We included 14 studies (909 participants) in this review. Surgical interventions, including laser therapy and cryotherapy, have never been studied by means of an RCT that included a no treatment or placebo arm. The included trials tested a range of medical and complementary treatments, in particular, vitamin A and retinoids (four studies); beta carotene or carotenoids (three studies); non-steroidal anti-inflammatory drugs (NSAIDs), specifically ketorolac and celecoxib (two studies); herbal extracts (four studies), including tea components, a Chinese herbal mixture and freeze-dried black raspberry gel; bleomycin (one study); and Bowman-Birk inhibitor (one study).We judged one study to be at low risk of bias, seven at unclear risk and six at high risk. In general, we judged the overall quality of the evidence to be low or very low, so findings are uncertain and further research is needed.Five studies recorded cancer incidence, only three of which provided useable data. None of the studies provided evidence that active treatment reduced the risk of oral cancer more than placebo: systemic vitamin A (RR 0.11, 95% CI 0.01 to 2.05; 85 participants, one study); systemic beta carotene (RR 0.71, 95% CI 0.24 to 2.09; 132 participants, two studies); and topical bleomycin (RR 3.00, 95% CI 0.32 to 27.83; 20 participants, one study). Follow-up ranged between two and seven years.Some individual studies suggested effectiveness of some proposed treatments, namely, systemic vitamin A, beta carotene and lycopene, for achieving clinical resolution of lesions more often than placebo. Similarly, single studies found that systemic retinoic acid and lycopene may provide some benefit in terms of improvement in histological features. Some studies also reported a high rate of relapse.Side effects of varying severity were often described; however, it seems likely that interventions were well accepted by participants because drop-out rates were similar between treatment and control groups.

AUTHORS' CONCLUSIONS

Surgical treatment for oral leukoplakia has not been assessed in an RCT that included a no treatment or placebo comparison. Nor has cessation of risk factors such as smoking been assessed. The available evidence on medical and complementary interventions for treating people with leukoplakia is very limited. We do not currently have evidence of a treatment that is effective for preventing the development of oral cancer. Treatments such as vitamin A and beta carotene may be effective in healing oral lesions, but relapses and adverse effects are common. Larger trials of longer duration are required to properly evaluate the effects of leukoplakia treatments on the risk of developing oral cancer. High-quality research is particularly needed to assess surgical treatment and to assess the effects of risk factor cessation in people with leukoplakia.

Prevention of Carcinogen-Induced Oral Cancer by Sulforaphane

Chronic exposure to carcinogens represents the major risk factor for head and neck squamous cell carcinoma (HNSCC). Beverages derived from broccoli sprout extracts (BSE) that are rich in glucoraphanin and its bioactive metabolite sulforaphane promote detoxication of airborne pollutants in humans. Herein, we investigated the potential chemopreventive activity of sulforaphane using in vitro models of normal and malignant mucosal epithelial cells and an in vivo model of murine oral cancer resulting from the carcinogen 4-nitroquinoline-1-oxide (4NQO). Sulforaphane treatment of Het-1A, a normal mucosal epithelial cell line, and 4 HNSCC cell lines led to dose- and time-dependent induction of NRF2 and the NRF2 target genes NQO1 and GCLC, known mediators of carcinogen detoxication. Sulforaphane also promoted NRF2-independent dephosphorylation/inactivation of pSTAT3, a key oncogenic factor in HNSCC. Compared with vehicle, sulforaphane significantly reduced the incidence and size of 4NQO-induced tongue tumors in mice. A pilot clinical trial in 10 healthy volunteers evaluated the bioavailability and pharmacodynamic activity of three different BSE regimens, based upon urinary sulforaphane metabolites and NQO1 transcripts in buccal scrapings, respectively. Ingestion of sulforaphane-rich BSE demonstrated the greatest, most consistent bioavailability. Mucosal bioactivity, defined as 2-fold or greater upregulation of NQO1 mRNA, was observed in 6 of 9 evaluable participants ingesting glucoraphanin-rich BSE; 3 of 6 ingesting sulforaphane-rich BSE; and 3 of 9 after topical-only exposure to sulforaphane-rich BSE. Together, our findings demonstrate preclinical chemopreventive activity of sulforaphane against carcinogen-induced oral cancer, and support further mechanistic and clinical investigation of sulforaphane as a chemopreventive agent against tobacco-related HNSCC. Cancer Prev Res; 9(7); 547-57. ©2016 AACR.

Erlotinib and the Risk of Oral Cancer: The Erlotinib Prevention of Oral Cancer (EPOC) Randomized Clinical Trial

IMPORTANCE

Standard molecularly based strategies to predict and/or prevent oral cancer development in patients with oral premalignant lesions (OPLs) are lacking.

OBJECTIVE

To test if the epidermal growth factor receptor inhibitor erlotinib would reduce oral cancer development in patients with high-risk OPLs defined by specific loss of heterozygosity (LOH) profiles. Secondary objectives included prospective determination of LOH as a prognostic marker in OPLs.

DESIGN

The Erlotinib Prevention of Oral Cancer (EPOC) study was a randomized, placebo-controlled, double-bind trial. Accrual occurred from November 2006 through July 2012, with a median follow-up time of 35 months in an ambulatory care setting in 5 US academic referral institutions. Patients with OPLs were enrolled in the protocol, and each underwent LOH profiling (N = 379); they were classified as high-risk (LOH-positive) or low-risk (LOH-negative) patients based on their LOH profiles and oral cancer history. The randomized sample consisted of 150 LOH-positive patients.

INTERVENTIONS

Oral erlotinib treatment (150 mg/d) or placebo for 12 months.

MAIN OUTCOMES AND MEASURES

Oral cancer-free survival (CFS).

RESULTS

A total of 395 participants were classified with LOH profiles, and 254 were classified LOH positive. Of these, 150 (59%) were randomized, 75 each to the placebo and erlotinib groups. The 3-year CFS rates in placebo- and erlotinib-treated patients were 74% and 70%, respectively (hazard ratio [HR], 1.27; 95% CI, 0.68-2.38; P = .45). The 3-year CFS was significantly lower for LOH-positive compared with LOH-negative groups (74% vs 87%, HR, 2.19; 95% CI, 1.25-3.83; P = .01). Increased EGFR gene copy number correlated with LOH-positive status (P < .001) and lower CFS (P = .01). The EGFR gene copy number was not predictive of erlotinib efficacy. Erlotinib-induced skin rash was associated with improved CFS (P = .01).

CONCLUSIONS AND RELEVANCE

In this trial, LOH was validated as a marker of oral cancer risk and found to be associated with increased EGFR copy number (the target of the intervention). Erlotinib did not, however, improve CFS in high-risk patients with LOH-positive or high-EGFR-gene-copy-number OPLs. These results support incorporation of LOH testing as a prognostic tool in routine clinical practice but do not support erlotinib use in this setting.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00402779.

Development of a Novel Marker Gene Based Assay System for Detection and Evaluation of Antiviral Agents with Activity against Papillomaviruses

A novel assay system has been developed in which expression of a human tissue-plasminogen activator (t-PA) gene, carried on a recombinant papillomavirus vector, is used as a marker for the presence of bovine papillomavirus type 1 (BPV-1) within transformed mouse C127 cells. This provides a relatively quick and simple means of identifying and evaluating agents with anti-papillomavirus activity. Using this system the antiviral activity and cytotoxicity of interferon and retinoic acid, have been investigated. After seven subcultures in the presence of 200 Units ml−1 mouse α and β interferon, t-PA expression was completely inhibited, with a concurrent alteration in cellular morphology, and restoration of contact inhibition. In accordance with the problems encountered with interferon therapy of human papillomavirus infections, these effects were dependent on the continued presence of interferon, its removal leading to a rapid return of t-PA expression, and reversion of cells to the transformed phenotype. In comparison, 2.0 μg ml−1 retinoic acid partially reduced t-PA expression (this effect was largely maintained even after removal of the inhibiting compound) but did not affect the transformed cell phenotype. These results are discussed in relation to other in vitro studies and also to the clinical treatment of human papillomavirus (HPV) disease.

Prognostic factors, predictive markers and cancer biology: the triad for successful oral cancer chemoprevention

Oral squamous cell carcinomas represent a significant cancer burden worldwide. Unfortunately, chemoprevention strategies investigated to date have failed to produce an agent considered standard of care to prevent oral cancers. Nonetheless, recent advances in clinical trial design may streamline drug development in this setting. In this manuscript, we review some of these improvements, including risk prediction tools based on molecular markers that help select patients most suitable for chemoprevention. We also discuss the opportunities that novel preclinical models and modern molecular profiling techniques will bring to the prevention field in the near future, and propose a clinical trials framework that incorporates molecular prognostic factors, predictive markers and cancer biology as a roadmap to improve chemoprevention strategies for oral cancers.

A Randomized Double-Blind Placebo-Controlled Phase IIB Trial of Curcumin in Oral Leukoplakia

Oral leukoplakia is a potentially malignant lesion of the oral cavity, for which no effective treatment is available. We investigated the effectiveness of curcumin, a potent inhibitor of NF-κB/COX-2, molecules perturbed in oral carcinogenesis, to treat leukoplakia. Subjects with oral leukoplakia (n = 223) were randomized (1:1 ratio) to receive orally, either 3.6 g/day of curcumin (n = 111) or placebo (n = 112), for 6 months. The primary endpoint was clinical response obtained by bi-dimensional measurement of leukoplakia size at recruitment and 6 months. Histologic response, combined clinical and histologic response, durability and effect of long-term therapy for an additional six months in partial responders, safety and compliance were the secondary endpoints. Clinical response was observed in 75 (67.5%) subjects [95% confidence interval (CI), 58.4-75.6] in the curcumin and 62 (55.3%; 95% CI, 46.1-64.2) in placebo arm (P = 0.03). This response was durable, with 16 of the 18 (88.9%; 95% CI, 67.2-96.9) subjects with complete response in curcumin and 7 of 8 subjects (87.5%) in placebo arm, demonstrating no relapse after 6 months follow-up. Difference in histologic response between curcumin and placebo was not significant (HR, 0.88, 95% CI, 0.45-1.71; P = 0.71). Combined clinical and histologic response assessment indicated a significantly better response with curcumin (HR, 0.50; 95% CI, 0.27-0.92; P = 0.02). Continued therapy, in subjects with partial response at 6 months, did not yield additional benefit. The treatment did not raise any safety concerns. Treatment of oral leukoplakia with curcumin (3.6 g for six months), thus was well tolerated and demonstrated significant and durable clinical response for 6 months. Cancer Prev Res; 9(8); 683-91. ©2016 AACR.

PPAR Activation and Decreased Proliferation in Oral Carcinoma Cells With 4-HPR

OBJECTIVE: To explore whether the mechanism of action of 4-hydroxyphenylretinamide (4-HPR, fenretidine), a synthetic retinoid, involves the functional activation of the nuclear hormone receptor class known as PPARs (peroxisome proliferator-activated receptors). Also, to examine whether anti-proliferative effects of this agent in head and neck cancer cells occur at biologically relevant concentrations.

STUDY DESIGN/METHODS: CA 9–22, NA, and UM SCC 11B cells were treated with 4-HPR during their log phase growth and functional activation of PPAR γ was evaluated by plate luminometry. Cellular proliferation was analyzed by standard MTT cell proliferation assays and cell counting. Student's t tests were performed for all experiments.

RESULTS: Significant dose-dependent increases in PPAR γ activation occurred in response to 4-HPR treatment. Proliferation was significantly inhibited by 4-HPR in a dose-dependent manner as judged by MTT and cell counting assays. These effects occurred at equimolar concentrations in both types of experiments within a range of clinically achievable doses (1–4 μM) of 4-HPR.

CONCLUSIONS: 4-HPR can functionally activate PPAR γ at clinically achievable doses. Decreased cancer cell proliferation secondary to PPAR γ activation has been observed in other malignancies as well as upper aerodigestive cancer. PPAR γ activation by 4-HPR represents another potential anti-cancer mechanism of action for this drug.

CLINICAL SIGNIFICANCE: PPAR γ activation represents a novel target for anti-cancer therapy for head and neck cancer and the current level of clinical toxicity of 4-HPR would be judged acceptable to utilize this agent alone or in combination chemotherapy.

Functional activation of PPARγ in human upper aerodigestive cancer cell lines

Upper aerodigestive cancer is an aggressive malignancy with relatively stagnant long-term survival rates over 20 yr. Recent studies have demonstrated that exploitation of PPARγ pathways may be a novel therapy for cancer and its prevention. We tested whether PPARγ is expressed and inducible in aerodigestive carcinoma cells and whether it is present in human upper aerodigestive tumors. Human oral cancer CA-9-22 and NA cell lines were treated with the PPAR activators eicosatetraynoic acid (ETYA), 15-deoxy-δ- 12,14-prostaglandin J2 (PG-J2), and the thiazolidinedione, ciglitazone, and evaluated for their ability to functionally activate PPARγ luciferase reporter gene constructs. Cellular proliferation and clonogenic potential after PPARγ ligand treatment were also evaluated. Aerodigestive cancer specimens and normal tissues were evaluated for PPARγ expression on gene expression profiling and immunoblotting. Functional activation of PPARγ reporter gene constructs and increases in PPARγ protein were confirmed in the nuclear compartment after PPARγ ligand treatment. Significant decreases in cell proliferation and clonogenic potential resulted from treatment. Lipid accumulation was induced by PPARγ activator treatment. 75% of tumor specimens and 100% of normal control tissues expressed PPARγ RNA, and PPARγ protein was confirmed in 66% of tumor specimens analyzed by immunoblotting. We conclude PPARγ can be functionally activated in upper aerodigestive cancer and that its activation downregulates several features of the neoplastic phenotype. PPARγ expression in human upper aerodigestive tract tumors and normal cells potentially legitimizes it as a novel intervention target in this disease. © 2016 Wiley Periodicals, Inc.

Impaired aldehyde dehydrogenase 1 subfamily member 2A-dependent retinoic acid signaling is related with a mesenchymal-like phenotype and an unfavorable prognosis of head and neck squamous cell carcinoma

Background

An inverse correlation between expression of the aldehyde dehydrogenase 1 subfamily A2 (ALDH1A2) and gene promoter methylation has been identified as a common feature of oropharyngeal squamous cell carcinoma (OPSCC). Moreover, low ALDH1A2 expression was associated with an unfavorable prognosis of OPSCC patients, however the causal link between reduced ALDH1A2 function and treatment failure has not been addressed so far.

Methods

Serial sections from tissue microarrays of patients with primary OPSCC (n = 101) were stained by immunohistochemistry for key regulators of retinoic acid (RA) signaling, including ALDH1A2. Survival with respect to these regulators was investigated by univariate Kaplan-Meier analysis and multivariate Cox regression proportional hazard models. The impact of ALDH1A2-RAR signaling on tumor-relevant processes was addressed in established tumor cell lines and in an orthotopic mouse xenograft model.

Results

Immunohistochemical analysis showed an improved prognosis of ALDH1A2^high OPSCC only in the presence of CRABP2, an intracellular RA transporter. Moreover, an ALDH1A2^highCRABP2^high staining pattern served as an independent predictor for progression-free (HR: 0.395, p = 0.007) and overall survival (HR: 0.303, p = 0.002), suggesting a critical impact of RA metabolism and signaling on clinical outcome. Functionally, ALDH1A2 expression and activity in tumor cell lines were related to RA levels. While administration of retinoids inhibited clonogenic growth and proliferation, the pharmacological inhibition of ALDH1A2-RAR signaling resulted in loss of cell-cell adhesion and a mesenchymal-like phenotype. Xenograft tumors derived from FaDu cells with stable silencing of ALDH1A2 and primary tumors from OPSCC patients with low ALDH1A2 expression exhibited a mesenchymal-like phenotype characterized by vimentin expression.

Conclusions

This study has unraveled a critical role of ALDH1A2-RAR signaling in the pathogenesis of head and neck cancer and our data implicate that patients with ALDH1A2^low tumors might benefit from adjuvant treatment with retinoids.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0476-0) contains supplementary material, which is available to authorized users.

Retinoids and rexinoids in cancer prevention: from laboratory to clinic

Early in the age of modern medicine the consequences of vitamin A deficiency drew attention to the fundamental link between retinoid-dependent homeostatic regulation and malignant hyperproliferative diseases. The term "retinoid" includes a handful of endogenous and a large group of synthetic derivatives of vitamin A. These multifunctional lipid-soluble compounds directly regulate target genes of specific biological functions and critical signaling pathways to orchestrate complex functions from vision to development, metabolism, and inflammation. Many of the retinoid activities on the cellular level have been well characterized and translated to the regulation of processes like differentiation and cell death, which play critical roles in the outcome of malignant transformation of tissues. In fact, retinoid-based differentiation therapy of acute promyelocytic leukemia was one of the first successful examples of molecularly targeted treatment strategies. The selectivity, high receptor binding affinity and the ability of retinoids to directly modulate gene expression programs present a distinct pharmacological opportunity for cancer treatment and prevention. However, to fully exploit their potential, the adverse effects of retinoids must be averted. In this review we provide an overview of the biology of retinoid (activated by nuclear retinoic acid receptors [RARs]) and rexinoid (engaged by nuclear retinoid X receptors [RXRs]) action concluded from a long line of preclinical studies, in relation to normal and transformed states of cells. We will also discuss the past and current uses of retinoids in the treatment of malignancies, the potential of rexinoids in the cancer prevention setting, both as single agents and in combinations.

Photodynamic therapy: a review and its prospective role in the management of oral potentially malignant disorders

With the unreliability of epithelial dysplasia as a predictor to determine the risk of future malignant development, subjectivity associated in evaluating dysplasia by pathologists and paucity of biomarkers that could accurately predict the progression risks in oral potentially malignant disorders (PMDs), eradication of the lesions appears to be the most desirable approach to minimize the risk of invasive cancer formation. Interventions, such as surgery and chemoprevention, have not shown promising long-term results in the treatment of these lesions, and lack of guidelines and general consensus on their management has incited much anxiety and doubts in both patients and community clinicians. Topical photodynamic therapy (PDT) is a minimally invasive and minimally toxic technique that in recent years has shown great promise in the management of PMDs. In this review, we describe the historical developments in the field of PDT, its basic mechanisms, as well as related clinical studies, and its challenges in the management of oral PMDs. Based on its high efficacy and low side effects, its high patient acceptance/compliance, the simplicity of the procedure and its minimal pretreatment preparation, topical PDT is believed to have potential to play an important role in the management of PMDs, especially of the low-grade dysplasia.

Molecular cancer prevention: Current status and future directions

The heterogeneity and complexity of advanced cancers strongly support the rationale for an enhanced focus on molecular prevention as a priority strategy to reduce the burden of cancer. Molecular prevention encompasses traditional chemopreventive agents as well as vaccinations and therapeutic approaches to cancer-predisposing conditions. Despite challenges to the field, we now have refined insights into cancer etiology and early pathogenesis; successful risk assessment and new risk models; agents with broad preventive efficacy (eg, aspirin) in common chronic diseases, including cancer; and a successful track record of more than 10 agents approved by the US Food and Drug Administration for the treatment of precancerous lesions or cancer risk reduction. The development of molecular preventive agents does not differ significantly from the development of therapies for advanced cancers, yet it has unique challenges and special considerations given that it most often involves healthy or asymptomatic individuals. Agents, biomarkers, cohorts, overall design, and endpoints are key determinants of molecular preventive trials, as with therapeutic trials, although distinctions exist for each within the preventive setting. Progress in the development and evolution of molecular preventive agents has been steadier in some organ systems, such as breast and skin, than in others. In order for molecular prevention to be fully realized as an effective strategy, several challenges to the field must be addressed. Here, the authors provide a brief overview of the context for and special considerations of molecular prevention along with a discussion of the results from major randomized controlled trials.

Aldehyde dehydrogenases and cancer stem cells

Aldehyde dehydrogenases (ALDHs), as essential regulators of aldehyde metabolism in the human body, protect organisms from damage induced by active aldehydes. Given their roles in different cancer types, ALDHs have been evaluated as potential prognostic markers of cancer. ALDHs exhibit high activity in cancer stem cells (CSCs) and may serve as markers of CSCs. Moreover, studies indicated that ALDHs and their regulated retinoic acid, reactive oxygen species and reactive aldehydes metabolism were strongly related with various properties of CSCs. Besides, recent research evidences have demonstrated the transcriptional and post-translational regulation of ALDH expression and activation in CSCs. Thus, this review focuses on the function and regulation of ALDHs in CSCs, particularly ALDH1A1 and ALDH1A3.

Suppressive function of low-dose deguelin on the invasion of oral cancer cells by downregulating tumor necrosis factor alpha-induced nuclear factor-kappa B signaling

BACKGROUND

Deguelin has both antiproliferation and antimetastasis activities. However, high-dose deguelin elicits many undesired side effects. The purpose of this study was to investigate whether the low-dose deguelin can prevent the metastasis of oral cancer.

METHODS

The dose effects of deguelin on metastasis of oral cancer cells were analyzed by in vitro invasion assay and an orthotropic xenograft mouse model. The involvement of tumor necrosis factor alpha (TNF-α)-induced nuclear factor-kappa B (NF-κB) signaling was examined by Western blot and reporter assay.

RESULTS

Low-dose deguelin, which has minimal cytotoxicity, significantly inhibited the invasion and migration of oral cancer cells. These inhibitory effects of low-dose deguelin were mediated by suppressing TNF-α-induced activation of IκB kinase leading to the inhibition of IκB phosphorylation, NF-κB transcriptional activity, and matrix metalloproteinase-2 (MMP2) expression. The low-dose deguelin treatment significantly inhibited tumor growth and invasion without systemic toxicity.

CONCLUSION

The low-dose deguelin suppressed the invasion and migration of oral cancer by downregulating TNF-α-induced NF-κB signaling. © 2015 Wiley Periodicals, Inc. Head Neck 38: E524-E534, 2016.

Chemoprevention targets for tobacco-related head and neck cancer: past lessons and future directions

Progress toward identifying an effective chemopreventive agent to reduce the incidence of head and neck squamous cell carcinoma (HNSCC) has been limited by poor efficacy and intolerable toxicity profiles. In this review, we summarize the biological basis of HNSCC chemoprevention, and outline challenges associated with identifying appropriate high-risk HNSCC populations for chemoprevention studies. We discuss findings and lessons learned from clinical trials that have investigated micronutrient and molecular targeting interventions. Finally, we introduce the concept of green chemoprevention, interventions based upon whole plant foods or simple extracts that may represent a safe and cost-conscious option for the next generation of studies. As our scientific understanding of HNSCC reaches new levels, the field is poised to develop chemoprevention studies based on rigorous biological validation with accessibility to all affected individuals regardless of socioeconomic barriers.

Fenretinide Perturbs Focal Adhesion Kinase in Premalignant and Malignant Human Oral Keratinocytes. Fenretinide's Chemopreventive Mechanisms Include ECM Interactions

The membrane-associated protein, focal adhesion kinase (FAK), modulates cell-extracellular matrix interactions and also conveys prosurvival and proliferative signals. Notably, increased intraepithelial FAK levels accompany transformation of premalignant oral intraepithelial neoplasia (OIN) to oral squamous cell carcinoma (OSCC). OIN chemoprevention is a patient-centric, optimal strategy to prevent OSCC's comorbidities and mortality. The cancer chemopreventive and synthetic vitamin A derivative, fenretinide, has demonstrated protein-binding capacities, for example, mTOR- and retinol-binding protein interactions. These studies used a continuum of human oral keratinocytes (normal-HPV E6/E7-transduced-OSCC) to assess potential fenretinide-FAK drug protein interactions and functional consequences on cellular growth regulation and motility. Molecular modeling studies demonstrated that fenretinide has approximately 200-fold greater binding affinity relative to the natural ligand (ATP) at FAK's kinase domain. Fenretinide also shows intermediate binding at FAK's FERM domain and interacts at the ATP-binding site of the closest FAK analogue, PYK2. Fenretinide significantly suppressed proliferation via induction of apoptosis and G2-M cell-cycle blockade. Fenretinide-treated cells also demonstrated F-actin disruption, significant inhibition of both directed migration and invasion of a synthetic basement membrane, and decreased phosphorylation of growth-promoting kinases. A commercially available FAK inhibitor did not suppress cell invasion. Notably, although FAK's FERM domain directs cell invasion, FAK inhibitors target the kinase domain. In addition, FAK-specific siRNA-treated cells showed an intermediate cell migration capacity; data which suggest cocontribution of the established migrating-enhancing PYK2. Our data imply that fenretinide is uniquely capable of disrupting FAK's and PYK2's prosurvival and mobility-enhancing effects and further extend fenretinide's chemopreventive contributions beyond induction of apoptosis and differentiation.

Retinoic acid receptors: from molecular mechanisms to cancer therapy

Retinoic acid (RA), the major bioactive metabolite of retinol or vitamin A, induces a spectrum of pleiotropic effects in cell growth and differentiation that are relevant for embryonic development and adult physiology. The RA activity is mediated primarily by members of the retinoic acid receptor (RAR) subfamily, namely RARα, RARβ and RARγ, which belong to the nuclear receptor (NR) superfamily of transcription factors. RARs form heterodimers with members of the retinoid X receptor (RXR) subfamily and act as ligand-regulated transcription factors through binding specific RA response elements (RAREs) located in target genes promoters. RARs also have non-genomic effects and activate kinase signaling pathways, which fine-tune the transcription of the RA target genes. The disruption of RA signaling pathways is thought to underlie the etiology of a number of hematological and non-hematological malignancies, including leukemias, skin cancer, head/neck cancer, lung cancer, breast cancer, ovarian cancer, prostate cancer, renal cell carcinoma, pancreatic cancer, liver cancer, glioblastoma and neuroblastoma. Of note, RA and its derivatives (retinoids) are employed as potential chemotherapeutic or chemopreventive agents because of their differentiation, anti-proliferative, pro-apoptotic, and anti-oxidant effects. In humans, retinoids reverse premalignant epithelial lesions, induce the differentiation of myeloid normal and leukemic cells, and prevent lung, liver, and breast cancer. Here, we provide an overview of the biochemical and molecular mechanisms that regulate the RA and retinoid signaling pathways. Moreover, mechanisms through which deregulation of RA signaling pathways ultimately impact on cancer are examined. Finally, the therapeutic effects of retinoids are reported.

Prevention of head and neck squamous cell carcinoma: removing the "chemo" from "chemoprevention"

The concept of chemoprevention whereby the use of a systemic agent is intended to halt the carcinogenesis process has been an attractive topic in head and neck squamous cell carcinoma (HNSCC). Yet, despite the significant efforts over the past decades and the substantial gain in knowledge of the biology of pre-malignant lesions of the head and neck, no tangible indications for chemoprevention have emerged for this disease. The negative results observed in the earlier larger studies using retinoids did not encourage further trials with these agents. Attention has been more recently focused on epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) as well as cyclo-oxygenase 2 (COX-2) inhibitors with early studies showing encouraging responses but rather poor tolerance to therapy. Natural compounds have gained more interest recently given preclinical evidence of activity as well as a low side effect profile. We herein offer a comprehensive overview of the field of chemoprevention in HNSCC with an in depth analysis of the challenges we face and discuss a road map for future directions.

Oral field cancerization: an update on current concepts

There always exists a field with genetically altered cells with a high risk of developing premalignant and malignant lesions. It may often happen that an individual stem cell is genetically altered and can cause the formation of a clone or a patch which is likely to turn into a tumor. This explains the higher recurrence rates following tumor resections. It is essential to identify and to treat this field in order to have greater chances to prevent cancer and achieve a better outcome. This article reports concepts, theories and markers for the assessment of field cancerization.

Chemoprevention of oral cancer: Green tea experience

Oral cancer has a well characterized progression from premalignant oral epithelial changes to invasive cancer, making oral squamous cell carcinoma an optimal disease for chemoprevention interventions prior to malignant transformation. The primary goal of chemoprevention here is to reverse, suppress, or inhibit the progression of premalignant lesions to cancer. Due to the extended duration of oral pathogenesis, its chemoprevention using natural products has been found promising due to their decreased dose and limited toxicity profiles. This review discusses with an emphasis on the clinical trials using green tea extract (GTE) in chemoprevention of oral premalignant lesions along with use of GTE as a chemopreventive agent in various other cancers as well. It is worthwhile to include green tea extract in an oral screening program for evaluating the premalignant lesions comparing the results between the treated and untreated group. Given the wide acceptance of green tea, its benefits may help in effective chemoprevention oral cancer.

The failure of cancer chemoprevention

Chemoprevention is proposed as a clinical analogue of population prevention, aimed at reducing likelihood of disease progression, not across the population, but in identified high-risk individuals and not by behavioral or lifestyle modification, but by the use of pharmaceutical agents. Cardiovascular chemoprevention is successful via control of hyperlipidemias and hypertension. However, chemoprevention of cancer is an almost universal failure: not only are some results null; even more frequently, there is an excess of disease, including disease that the agents were chosen specifically to reduce. A brief introduction is followed by the evidence for a wide variety of agents and their largely deleterious, sometimes null, and in one case, largely beneficial, consequences as possible chemopreventives. The agents include (i) those that are food derived and their synthetic analogues: β-carotene, folic acid, retinol and retinoids, vitamin E, multivitamin supplements, vitamin C, calcium and selenium and (ii) agents targeted at metabolic and hormonal pathways: statins, estrogen and antagonists, 5α-reductase inhibitors. There are two agents for which there is good evidence of benefit when the strategy is focused on those at defined high risk but where wider application is much more problematic: aspirin and tamoxifen. The major problems with cancer chemoprevention are presented. This is followed by a hypothesis to explain the failure of cancer chemoprevention as an enterprise, arguing that the central tenets that underpin it are flawed and showing why, far from doing good, cancer chemoprevention causes harm.

Potentially malignant disorders of the oral cavity: current practice and future directions in the clinic and laboratory

Despite commendable progress in the prevention, detection, and treatment of a wide variety of solid tumor types, oral squamous cell carcinoma (OSCC) remains a significant health burden across the globe. OSCC carcinogenesis involves accumulation of genetic alterations that coincide with the multistep malignant transformation of normal oral epithelium. OSCC is often first diagnosed at late stages of the disease (advanced regional disease and/or metastasis). Delayed diagnosis precludes successful treatment and favorable outcomes. In clinical practice, opportunities exist to identify patients with oral potentially malignant disorders (OPMDs), which precede the development of cancer. This review addresses the current status of laboratory and clinical research on OPMDs, with emphasis on leukoplakia and erythroplakia. OSF is also presented, though there is a paucity of published studies on this disorder. We focus on findings that could translate into earlier diagnosis and more efficacious treatment of those lesions with significant malignant potential. We explore how markers of OPMD malignant transformation might be implemented into current diagnostic practice to help clinicians objectively stratify patients into treatment/follow-up groups according to relative risk. We provide an overview of recently concluded and ongoing OPMD chemoprevention trials. We describe laboratory OPMD models that can be used to not only to reveal the genetic and molecular intricacies of oral cancer but also to develop novel screening methods and therapeutic approaches. Finally, we call for targeted screening programs of at-risk populations in order to facilitate diagnosis and treatment of OPMD and early OSCC.

Chemoprevention of squamous cell carcinoma of the head and neck: no time to lose momentum

The prospects for chemoprevention to reduce the incidence of squamous cell carcinoma of the head and neck (SCCHN) are great. The tissue at risk for harboring disease is relatively accessible for examination and biopsy. Patients appropriate for study can be easily identified by their risk factors and the presence of premalignant lesions. Our understanding of the pathogenesis of SCCHN is ever increasing, and offers new opportunities to explore strategies for prevention therapies. In this issue of Cancer Prevention Research, Saba and colleagues report on a phase Ib trial of celecoxib plus erlotinib to prevent progression to higher-grade dysplasia or invasive carcinoma in patients with oral premalignant lesions. The overall response rate was 57%, though by the time of last analysis, 85% of patients relapsed. In this commentary, challenges to the success of chemoprevention clinical trials for SCCHN, such as pitfalls in using surrogate biomarkers and reversal of histologic premalignant changes as study endpoints, are discussed. In addition, strategies to help ensure further development in the field of head and neck cancer prevention are reviewed. These include focusing efforts on tobacco cessation and human papillomavirus vaccination, targeting key molecular drivers of head and neck carcinogenesis, and focusing on combination strategies that have the potential to eradicate premalignant clones, even if some toxicity is encountered.

Headway and hurdles in the clinical development of dietary phytochemicals for cancer therapy and prevention: lessons learned from vitamin A derivatives

Accumulating epidemiologic and preclinical evidence support the pharmacologic use of a variety of dietary chemicals for the prevention and treatment of cancer. However, it will be challenging to translate these findings into routine clinical practice since phytochemicals have pleiotropic biological activities that have to be balanced for optimal efficacy without unacceptable and potentially unanticipated toxicities. Correctly matching patient populations and settings with optimal, natural product-based phytochemical therapies will require a greater understanding of the specific mechanisms underlying the efficacy, toxicity, and resistance of each agent in a variety of normal, premalignant, and malignant settings. This, in turn, necessitates continued commitment from the basic research community to guide carefully designed and informed clinical trials. The most developed class of anticancer phytochemicals consists of the derivatives of vitamin A called retinoids. Unlike other natural product chemicals currently under study, the retinoids have been extensively tested in humans. Over 30 years of clinical investigation has resulted in several disappointments, but there were some spectacular successes where certain retinoid-based protocols are now FDA-approved standard of care therapies to treat specific malignancies. Furthermore, retinoids are one of the most evaluated pharmacologic agents in the ultra-challenging setting of interventional cancer prevention. This review will summarize the development of retinoids in cancer therapy and prevention with an emphasis on currently proposed mechanisms mediating their efficacy, toxicity, and resistance.

PPARγ in head and neck cancer prevention

Head and neck cancer is a major source of morbidity and mortality worldwide. Intervention during the early phases of carcinogenesis represents a promising new strategy for curbing the devastating effects of this disease and its primary treatment modalities, surgery and radiation with or without concomitant chemotherapy. This review focuses on the peroxisome proliferator-activated receptor gamma (PPARγ) as a target for chemoprevention of oral cancer. Accumulating data suggest that ligands of PPARγ, which include the thiazolidinedione class of agents approved for the treatment of diabetes, inhibit cancer cell growth in vitro and in animal carcinogenesis models, providing the rationale for testing this approach in populations at risk for head and neck cancer.

Chemoprevention of lung cancer: concepts and strategies

Lung cancer develops in a stepwise fashion, with an accumulation of molecular alterations progressing through preinvasive steps to invasive disease. This progression could be arrested or reversed through pharmacologic treatments, which are known as cancer chemoprevention. Preclinical and clinical findings relating to different classes of candidate chemopreventive agents provide support for this strategy as an active and promising approach for controlling this disease.

Chemoprevention of head and neck squamous cell carcinoma through inhibition of NF-κB signaling

Nuclear factor-kappa B (NF-κB) transcription factors regulate cellular processes such as inflammation and cell survival. The NF-κB pathway is often activated with development and progression of head and neck squamous cell carcinoma (HNSCC). As such, NF-κB represents an attractive target for chemoprevention. HNSCC involves progression of lesions from premalignant to malignant, providing a window of opportunity for intervention with chemopreventive agents. Appropriate chemopreventive agents should be inexpensive, nontoxic, and target important pathways involved in the development of HNSCC. Several such agents that inhibit the NF-κB pathway have been investigated in HNSCC. Retinoids have been studied most extensively but have shown limited potential in human trials. Epidermal growth factor receptor inhibitors and PI3K-mTOR inhibitors may benefit a subset of patients. Other agents such as green tea extract and curcumin are appealing because they are generally regarded as safe. In contrast, there is evidence that Vitamin E supplementation may actually increase mortality of cancer patients. Repurposed drugs such as cyclooxygenase (COX) inhibitors and antidiabetic drugs are an emerging area of interest. Future research to develop agents with lower toxicity and higher specificity for the NF-κB pathway, and to target these therapies to individual patient genetic signatures should help to increase the utility of chemoprevention in HSNCC.

The invisible arm of immunity in common cancer chemoprevention agents

Immunoprevention refers to a strategy of preventing pathogen-associated and spontaneous cancers through the use of vaccines, antibodies, and immune modulators. Immune modulators function by enhancing the endogenous ability of the immune system to monitor for malignancy, so-called "immunosurveillance." There is growing evidence that many of the most promising cancer chemoprevention agents including aspirin, COX-2 inhibitors, aromatase inhibitors, and bisphosphonates mediate their effects, in part, by enhancing immunosurveillance and reversing the immune evasive mechanisms that premalignant lesions use. In the following review, we introduce critical components of the human immune surveillance system-dendritic cells, T cells, and immune suppressive cells-and discuss the emerging data suggesting that common chemoprevention agents may modulate the function of these immunologic cells.

Retinoids for preventing the progression of cervical intra-epithelial neoplasia

BACKGROUND

Invasive cervical carcinoma is preceded by a precancerous phase, cervical intra-epithelial neoplasia (CIN), which can be detected on cervical smears and confirmed by colposcopy and biopsy. Moderate and severe cases of intra-epithelial neoplasia (CIN2 and CIN3) are treated mainly with surgery to prevent progression to invasive carcinoma. Medical methods of preventing the progression or inducing the regression of CIN are needed. Retinoids are potent modulators of epithelial cell growth and differentiation that may have potential for the treatment of CIN.

OBJECTIVES

To ascertain whether retinoids can cause regression or prevent progression of CIN.

SEARCH METHODS

We searched the Cochrane Gynaecological Cancer Review Group's Specialised Register and Non-Trials Database, the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 3, 2010), and MEDLINE and EMBASE (July 2010).For the 2013 update, the searches were re-run as follows: CENTRAL, Issue 3, 2013; MEDLINE, April, Week 2, 2013; and EMBASE, Week 16, 2013.

SELECTION CRITERIA

Randomized controlled trials (RCTs) and non-RCTs of retinoids for treating CIN in women.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data from the trials. Adverse effects information was also collected from the trials.

MAIN RESULTS

Five RCTs comparing the efficacy of four different retinoids were identified. Two studies examined the effects on CIN2 and CIN3 of the retinoids N-(4-hydroxyphenyl)retinamide (fenretinide) and 9-cis-retinoic acid (aliretinoin) given orally. Two examined the effect of all-trans-retinoic acid administered topically to the cervix. The fifth study investigated the use of 13-cis-retinoic acid (isotretinoin) given orally to human immunodeficiency virus (HIV)-positive participants with CIN1 and condyloma.Four studies reported no significant effect of retinoids on the progression to higher grades of CIN, and the fifth did not report data on progression. In all studies retinoids had no significant effect on regression of CIN3. Two studies reported that retinoids were associated with regression of CIN2. One reported a greater complete regression of CIN2 over that seen with placebo, which was of borderline statistical significance (odds ratio (OR) 0.5, 95% confidence interval (CI) 0.25 to 1.02). The other study reported a nonsignificant dose-related trend toward increased rates of complete and partial regression compared with placebo. One study reported significantly worse outcomes in women receiving retinoid (OR for regression 6.00, 95% CI 1.00 to 35.91). In general, the retinoid medications were well tolerated.In the 2010 review and in this update, no new studies were identified for inclusion.

AUTHORS' CONCLUSIONS

The retinoids studied are not effective in causing regression of CIN3 but may have some effect on CIN2. The data on CIN1 are inadequate. Retinoids are not effective in preventing progression of CIN of any grade. At the doses given for the duration of treatment studied, the retinoids were reasonably well tolerated.

Oral premalignancy: the roles of early detection and chemoprevention

Premalignancy and chemoprevention studies in head and neck cancer typically focus on the oral cavity. Avoiding or cessation of alcohol and smoking, early detection of potentially malignant disorders or cancer, and early detection of recurrent and/or second primary tumor form the basis of prevention of oral cancer. Analysis of tissue prospectively collected in evaluation of retinoids for chemoprevention trials allowed identification of molecular biomarkers of risk to develop oral cancer, loss of heterozygosity being the most validated one. Improving risk assessment and identification of new targets for chemoprevention represent the main challenges in this field.

Recurrence patterns and management of oral cavity premalignant lesions

OBJECTIVE

To gain an understanding of head and neck mucosal premalignant recurrence and progression based on histology, treatment modality, and risk factors.

DESIGN

Retrospective chart review.

SETTING

Academic medical center.

PATIENTS

Patients who were followed or treated for oral cavity dysplasia/carcinoma in situ.

MAIN OUTCOMES MEASURES

Comparisons with clinical features, degree of dysplasia, anatomical location, rate of recurrences as well as malignant transformation and overall outcome were made.

RESULTS

Of the 136 patients who were included in the study, 20% (n = 27) initially presented with mild dysplasia, 39% (n = 53) with moderate dysplasia, 21% (n = 29) with severe dysplasia, and 20% (n = 27) with carcinoma in situ. Wide local excision (HR 0.54, p = 0.05) was associated with reduced local recurrence in comparison to observation. In comparison to observation, both wide local excision (HR 0.43, p = 0.04) and CO(2)/NO Yag laser treatment (HR 0.14, p = 0.02) of dysplastic lesions significantly reduced progression to cancer. Management of mild dysplasia included observation (n = 13), excision (n = 10) and laser therapy (n = 3). Six of the 13 observed patients suffered a premalignancy recurrence, whereas only 4 of the 13 patients who underwent excision/laser treatment experienced a recurrence. Similarly, 5/13 observed patients eventually progressed to malignancy in comparison to only 2/13 patients who underwent initial excision/laser treatment.

CONCLUSION

Wide excision and/or ablation of head and neck mucosal premalignancy is more effective than observation in preventing recurrence of premalignancy and progression to malignancy. Mild dysplasia has a potentially high rate of recurrence and progression to malignancy when observed, and may be treated by wide excision or ablation.

Laser-assisted microdissection in translational research: theory, technical considerations, and future applications

Molecular profiling already exerts a profound influence on biomedical research and disease management. Microdissection technologies contribute to the molecular profiling of diseases, enabling investigators to probe genetic characteristics and dissect functional physiology within specific cell populations. Laser-capture microdissection (LCM), in particular, permits collation of genetic, epigenetic, and gene expression differences between normal, premalignant, and malignant cell populations. Its selectivity for specific cell populations promises to greatly improve the diagnosis and management of many human diseases. LCM has been extensively used in cancer research, contributing to the understanding of tumor biology by mutation detection, clonality analysis, epigenetic alteration assessment, gene expression profiling, proteomics, and metabolomics. In this review, we focus on LCM applications for DNA, RNA, and protein analysis in specific cell types and on commercially available LCM platforms. These analyses could clinically be used as aids to cancer diagnosis, clinical management, genomic profile studies, and targeted therapy. In this review, we also discuss the technical details of tissue preparation, analytical yields, tissue selection, and selected applications using LCM.

The role of aldehyde dehydrogenase (ALDH) in cancer drug resistance

Chemotherapy in cancer patients is still not satisfactory because of drug resistance. The main mechanism of drug resistance results from the ability of cancer cells to actively expel therapeutic agents via transport proteins of the ABC family. ABCB1 and ABCG2 are the two main proteins responsible for drug resistance in cancers. Recent investigations indicate that aldehyde dehydrogenase (ALDH) can also be involved in drug resistance. Expression of the ABC transporters and ALDH enzymes is observed in normal stem cells, cancer stem cells and drug resistant cancers. Current chemotherapy regimens remove the bulk of the tumour but are usually not effective against cancer stem cells (CSCs) expressing ALDH. As a result, the number of ALDH positive drug resistant CSCs increases after chemotherapy. This indicates that therapies targeting drug resistant CSCs should be developed. A number of therapies targeting CSCs are currently under investigation. These therapies include differentiation therapy using different retinoic acids (RA) as simple agents or in combination with DNA methyltransferase inhibitors (DNMTi) and/or histone deacetylase inhibitors (HDACi). Therapies that target cancer stem cell signaling pathways are also under investigation. A number of natural compounds are effective against cancer stem cells and lead to decreasing numbers of ALDH positive cells and downregulation of the ABC proteins. Combinations of differentiation therapies or therapies targeting CSC signaling pathways with classical cytostatics seem promising. This review discusses the role of ALDH and ABC proteins in the development of drug resistance in cancer and current therapies designed to target CSCs.

Not significant but important

Armstrong and colleagues report the result of a large Phase IIb randomized trial evaluating the effectiveness of a preparation of the Bowman Birk Inhibitor compared with an oral placebo in reversing the extent of oral leukoplakia as measured visually by pathology or a battery of intermediate end points. In this editorial, we review the report of this negative clinical trials result to highlight the clinical trial process used in evaluating this previously promising chemoprevention agent. Publishing this report is important to address concerns with publication bias. The challenges in running a chemoprevention trial are reviewed with suggestions to enhance progress going forward. Conceptually, developing drugs to intercept the early stages of carcinogenesis is very attractive, but progress in this area has been slow. Two opportunities to overcome this reality are discussed. These measures include the broader use of neoadjuvant, window-of-opportunity trials with new candidate chemoprevention agents to get more textured information about the mechanistic impact of the drug exposure in previously untreated early tumor tissue. In addition, we discuss the use of new intermediate end point markers such as with optical imaging tools to obtain a more objective and quantitative assessment of drug response.

An evidence-based systematic review of vitamin A by the natural standard research collaboration

An evidence-based systematic review of vitamin A by the Natural Standard Research Collaboration consolidates the safety and efficacy data available in the scientific literature using a validated and reproducible grading rationale. This paper includes written and statistical analysis of clinical trials, plus a compilation of expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

New perspectives of curcumin in cancer prevention

Numerous natural compounds have been extensively investigated for their potential for cancer prevention over the decades. Curcumin, from Curcuma longa, is a highly promising natural compound that can be potentially used for chemoprevention of multiple cancers. Curcumin modulates multiple molecular pathways involved in the lengthy carcinogenesis process to exert its chemopreventive effects through several mechanisms: promoting apoptosis, inhibiting survival signals, scavenging reactive oxidative species (ROS), and reducing the inflammatory cancer microenvironment. Curcumin fulfills the characteristics for an ideal chemopreventive agent with its low toxicity, affordability, and easy accessibility. Nonetheless, the clinical application of curcumin is currently compromised by its poor bioavailability. Here, we review the potential of curcumin in cancer prevention, its molecular targets, and mechanisms of action. Finally, we suggest specific recommendations to improve its efficacy and bioavailability for clinical applications.