Chemoprevention of Head and Neck Cancers: Does It Have Only One Face?

The potential preventive effect of dietary phytochemicals In Vivo

INTRODUCTION

Chemoprevention refers to using specific substances during oncogenesis. Curcumin and catechins are both polyphenol types of phytochemicals present in curcuma longa and green tea. The effect of curcumin is synergistic with epigallocatechin gallate, the most abundant polyphenol in tea.

AIM

To evaluate and compares the chemopreventive effect of both green tea and curcumin (each individually and in combination) through induction of hamster buccal pouch carcinoma.

MATERIALS AND METHODS

Squamous cell carcinoma was chemically induced in fifty Syrian golden hamsters divided into 5 groups (10 each). The first group was used as a normal control group. The second group received the carcinogenic agent only. The other three groups received green tea, curcumin, and a combination of both, respectively. Flow cytometry, immunofluorescence, and immunohistochemical assays were used to evaluate apoptosis, proliferation, and angiogenesis. ANOVA test was used to analyze the results between the study groups.

RESULTS

The cells of the positive control group (B) resulted in 11.57% apoptosis. In the study groups, treatment of the cells with green tea (C), and curcumin (D) and both of them (E) showed increased apoptosis. The fluorescent image in group B showed an increase of the red fluorescence in the nucleus and cytoplasm of the squamous cell carcinoma cells while groups C, D, and E showed a decrease of the red fluorescence in the nuclei of the squamous cell carcinoma cells. The microvessel density was higher in the positive control group as compared to the treated groups.

CONCLUSIONS

The combination of green tea and curcumin has a significant chemopreventive effect against oral carcinogenesis.

Precancerous Lesions of the Head and Neck Region and Their Stromal Aberrations: Piecemeal Data

Head and neck squamous cell carcinomas (HNSCCs) develop through a series of precancerous stages from a pool of potentially malignant disorders (PMDs). Although we understand the genetic changes that lead to HNSCC, our understanding of the role of the stroma in the progression from precancer to cancer is limited. The stroma is the primary battleground between the forces that prevent and promote cancer growth. Targeting the stroma has yielded promising cancer therapies. However, the stroma at the precancerous stage of HNSCCs is poorly defined, and we may miss opportunities for chemopreventive interventions. PMDs already exhibit many features of the HNSCC stroma, such as inflammation, neovascularization, and immune suppression. Still, they do not induce cancer-associated fibroblasts or destroy the basal lamina, the stroma's initial structure. Our review aims to summarize the current understanding of the transition from precancer to cancer stroma and how this knowledge can reveal opportunities and limitations for diagnostic, prognostic, and therapeutic decisions to benefit patients. We will discuss what may be needed to fulfill the promise of the precancerous stroma as a target to prevent progression to cancer.

Anticancer activity of Vicenin-2 against 7,12 dimethylbenz[a]anthracene-induced buccal pouch carcinoma in hamsters

Buccal mucosa carcinoma is a significant cause of death in developing nations. Vicenin-2 is a significant bioactive compound found in Ocimum sanctum Linn or Tulsi that possesses several pharmacologic properties. Our focus is to understand the possible impact of Vicenin-2 on 7,12-dimethylbenz[a]anthracene (DMBA)-induced oral carcinogenesis in hamsters. Buccal carcinoma was induced by treatment with carcinogenic DMBA, three times a week for 14 weeks. We determined 100% tumor incidence, abnormal tumor volume, inclined tumor burden, and deduced body weight in DMBA-induced oral squamous cell carcinoma (OSCC) hamsters. The upregulation of cytokine levels (interleukin [IL]-6, IL-1β, and tumor necrosis factor-alpha [TNF-α]) was observed in DMBA-induced OSCC hamsters. Moreover, dysplastic, hyperplastic, and squamous cell carcinoma was identified in the DMBA-induced OSCC hamsters. The diminished activities of lipid peroxidation and enzymatic/nonenzymatic antioxidants were observed in DMBA-induced hamsters. Furthermore, the high expression of proliferating cell nuclear antigen (PCNA), Cyclin-D1, and Bcl-2, and attenuated Bax expression were observed in DMBA-induced hamsters. Our study results explored that Vicenin-2 (30 mg/kg) treated with DMBA-brushed hamsters averted tumor incidence, improved the antioxidant status, and inhibited lipid peroxidation. Moreover, Vicenin-2 inhibited the immunohistochemical expression of PCNA, Cyclin-D1, and Bcl-2, and significantly restored apoptotic Bax levels. The Vicenin-2 treatment prevents the lesion formation in the oral epithelium of the DMBA-induced hamsters. The Vicenin-2 treatment potentially halts the proinflammatory cytokines (IL-6, IL-1β, and TNF-α) production in OSCC hamsters. Thus, we proved that Vicenin-2 prevents DMBA-induced buccal carcinogenesis in hamsters via improving antioxidants by modulating apoptotic and cytokines signaling pathways.

Chemopreventive Agents in Oral Premalignancy: A Medical Management Review

Aims and Objective:

The term chemoprevention denotes the use of specific natural or synthetic chemical agents to prevent carcinogenesis. Chemoprevention may help delay the process of carcinogen activation and prevent the conversion of preneoplastic cells. These agents play an active role in the secondary level of prevention and reduce malignancy-associated morbidity and mortality. A new term, “prophylactic antioxidant therapy,” was coined and proposed. This review has assessed all major chemopreventive agents used for oral premalignancy and malignant conditions, which will reduce the economic burden on the patients.

Materials and Methods:

A systematic literature search was performed using PubMed, Medline, Embase, Cochrane Library, and EBSCO search, with language restriction to English. The search incorporated published literature from 1990 to 2018 using the medical subject heading terms. Literature search was performed using the following keywords: Chemoprevention, Premalignancy, and Oral Malignancy.

Results:

Of 99 publications related to the search strategy, 45 full articles relevant to the chemopreventive agents in premalignacy and oral malignancy were acquired for further inspection. Of the 45 articles, 30 met the inclusion criteria. Data were collected, and a brief summary of the studies regarding different chemopreventive agents that were most commonly used in oral premalignancy and malignancies was written.

Conclusion:

This review suggests administration of major chemopreventive agents for superior prognosis in individuals with an elevated risk of premalignancy and malignancy.

Identifying potential prognostic biomarkers in head and neck cancer based on the analysis of microRNA expression profiles in TCGA database

The present study aimed to identify sensitive, specific and independent prognostic biomarkers in head and neck cancer (HNC) based on microRNA expression profiles and other high‑throughput sequencing data in The Cancer Genome Atlas (TCGA) database. Identification of such prognostic biomarkers could provide insight into HNC diagnosis and treatment. The differential expression profiles of microRNAs between HNC tissues and adjacent cancer tissues in the TCGA database were analyzed (log fold‑change >2; P<0.01). Univariate and multivariate Cox regression analyses of the differentially expressed microRNAs were performed to determine those significantly related to the survival of patients with HNC. The identified microRNAs were verified by survival and receiver operating characteristic curve analyses. To better predict prognosis, a combined prognostic model (risk equation) was established based on the risk coefficient of each microRNA, calculated by a multivariate Cox regression analysis, and the risk score was calculated. To explore the signaling pathways related to prognosis, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses were performed on the differentially expressed genes between the high‑risk and low‑risk groups, grouped according to the median risk score. A total of 89 differentially expressed microRNAs between HNC and adjacent cancer tissues were screened, 11 of which were identified as risk factors related to HNC survival by the univariate Cox regression analysis (P<0.05). The multivariate Cox regression analysis showed that three of the 11 microRNAs, hsa‑miR‑99a, hsa‑miR‑499a and hsa‑miR‑1911 (all P<0.01), were identified as independent risk factors significantly related to patient survival. The risk equation used was as follows: Risk score=(‑0.1597 x hsa‑miR‑99a) + (0.1871 x hsa‑miR‑499a) + (0.1033 x hsa‑miR‑1911). KEGG and GO analyses showed that the JAK‑STAT signaling pathway and some metabolic pathways were associated with HNC prognosis. The present study suggested that hsa‑miR‑99a, hsa‑miR‑499a and hsa‑miR‑1911 may serve as potential prognostic biomarkers in HNC.