Apoptosis-inducing activity and tumor-specificity of antitumor agents against oral squamous cell carcinoma

A Combination of Curcumin and Lactobacillus rhamnosus GG Inhibits Viability and Induces Apoptosis in SCC-9 Human Oral Squamous Cell Carcinoma Cells

The aim of this study was to evaluate the effect of curcumin combined with Lactobacillus rhamnosus GG cell-free supernatant (LGG CFS) on the proliferation and induction of apoptosis in SCC-9 oral squamous cell carcinoma (OSCC) cells. Curcumin (40 µg/ml) and 25% v/v LGG CFS (108 CFU/ml), both alone and in a combination regimen, significantly decreased the viability of SCC-9 cells and normal human gingival fibroblast (HGF) cells. Interestingly, the combination of low doses of curcumin (5 µg/ml) and 25% v/v LGG CFS (106 CFU/ml) had no effect on the HGF cells but significantly inhibited the viability of SCC-9 cells (p < 0.05). Flow cytometric analysis revealed that SCC-9 cells treated with the combination of low-dose curcumin and low-dose LGG CFS had a higher apoptotic rate than the cells in the control group and the single treatment groups (p < 0.05). The combined treatment also significantly increased the Bax/Bcl2 mRNA and protein expression in SCC-9 cells (p < 0.05) but not in HGF cells, indicating the underlying mechanism of the combination regimen. There was no significant difference in caspase-3 protein expression or the Bcl-xL/Bak and Mcl-1/Bak ratios between the treatment and control groups in both cell lines. These findings suggested that the coadministration of curcumin and LGG could exhibit anticancer effects in SCC-9 cells without causing toxicity to normal fibroblast cells.

Esculetin has therapeutic potential via the proapoptotic signaling pathway in A253 human submandibular salivary gland tumor cells

Esculetin is a natural lactone that is commonly derived from coumarins. According to previous experiments using human cancer cells, esculetin has potent antitumor activity; it also inhibits proliferation and induces the apoptosis of cancer cells. In the present study, the anti-proliferative effect of esculetin on the submandibular salivary gland tumor cell line, A253, was evaluated via in vitro and in vivo analyses. Furthermore, the anti-cancer effects of esculetin in A253 cells and a xenograft model of salivary gland tumors were determined using 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide and TUNEL assay, apoptosis protein array, quantitative polymerase chain reaction and western blot analysis. Esculetin (50-150 µM) was demonstrated to have an anti-proliferative effect in the A253 cell line in vitro; this observed effect was dependent on the dose and duration of treatment. Esculetin also increased the levels of Bax, cleaved caspase-3, cleaved-9 and cleaved poly (ADP-ribose) polymerase apoptosis-related proteins, and decreased the expression levels of the Bcl-2 anti-apoptotic protein. With respect to apoptosis regulation, esculetin significantly decreased the proliferation of tumor cells in a xenograft model (100 mg/kg/day) for 18 days. Overall, esculetin could be a potential oral anticancer drug against salivary gland cancer.

MicroRNA-134 inhibits tumor stem cell migration and invasion in oral squamous cell carcinomas via downregulation of PI3K-Akt signaling pathway by inhibiting LAMC2 expression

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the most common malignant neoplasm of the mouth. Some studies have found that multiple microRNAs (miRs) participate in OSCC physiological and pathological processes.

METHODS

We explored the mechanism of action of miR-134 in OSCC involving the PI3K-Akt signaling pathway. Different bioinformatics methods were used to analyze the potential genes and their related miRs in OSCC. Tumor stem cells were separated from OSCCs through magnetic cell sorting. Regulatory pattern between miR-134 and LAMC2 in OSCC was evaluated by ectopic expression, knockdown and reporter assay experiments. The expression of miR-134, LAMC2, genes in PI3K-Akt signaling pathway, and apoptosis-related genes was detected. Cell proliferation was assessed by MTT assay, cell invasion by scratch test, cell migration by Transwell assay, cell cycle and apoptosis by flow cytometry, and cell growth and migration by xenograft tumor in nude mice. LAMC2 was predicted as the crucial factor related to OSCC using different chip data, and miR-134 was predicted to specifically bind LAMC2 in all five databases.

RESULTS

Overexpressed miR-134 or silenced LAMC2 was observed to inhibit cell proliferation, migration, invasion of OSCC cells, growth of subcutaneous xenograft in nude mice, as well as promote OSCC cell apoptosis. LAMC2, a target gene of miR-134, decreased following miR-134 promotion, while the PI3K-Akt signaling pathway was inactivated following LAMC2 knockdown. Furthermore, we also observed that the effect of overexpressed miR-134 was enhanced when LAMC2 was knocked down.

CONCLUSIONS

Taken together, these findings suggest that miR-134-mediated direct downregulation of LAMC2 inhibits migration and invasion of tumor stem cells in OSCC by suppressing the PI3K-Akt signaling pathway.

Synthesis and Different Effects of Biotinylated PAMAM G3 Dendrimer Substituted with Nimesulide in Human Normal Fibroblasts and Squamous Carcinoma Cells

Squamous cell carcinoma (SCC) remains a main cause of mortality in patients with neck and head cancers, with poor prognosis and increased prevalence despite of available therapies. Recent studies have identified a role of cyclooxygenases, particularly inducible isoform cyclooxygenase-2 (COX-2) and its metabolite prostaglandin E2 (PGE₂) in cancer cell proliferation, and its inhibition become a target for control of cancer development, particularly in the view of recognized additive or synergic action of COX-2 inhibitors with other forms of therapy. Nimesulide (N), the selective COX-2 inhibitor, inhibits growth and proliferation of various types of cancer cells by COX-2 dependent and independent mechanisms. In the presented study, the conjugates of biotinylated third generation poly(amidoamine) dendrimer (PAMAM) with covalently linked 18 (G3^B18N) and 31 (G3^B31N) nimesulide residues were synthesized and characterized by NMR spectroscopy. Biological properties of conjugates were evaluated, including cytotoxicity, proliferation, and caspase 3/7 activities in relation to COX-2/PGE₂ axis signaling in human normal fibroblast (BJ) and squamous cell carcinoma (SCC-15). Both conjugates exerted a selective cytotoxicity against SCC-15 as compared with BJ cells at low 1.25-10 µM concentration range and their action in cancer cells was over 250-fold stronger than nimesulide alone. Conjugates overcome apoptosis resistance and sensitized SCC-15 cells to the apoptotic death independently of COX-2/PGE₂ axis. In normal human fibroblasts the same concentrations of G3^B31N conjugate were less effective in inhibition of proliferation and induction of apoptosis, as measured by caspase 3/7 activity in a manner depending on increase of PGE₂ production by either COX-1/COX-2.

Epigallocatechin-3-gallate affects the proliferation, apoptosis, migration and invasion of tongue squamous cell carcinoma through the hippo-TAZ signaling pathway

The purpose of the present study was to investigate the mechanism by which epigallocatechin-3-gallate (EGCG) inhibits the biological behaviors of the tongue squamous cell carcinoma (TSCC) through the Hippo-tafazzin (TAZ) signaling pathway and to provide insights into molecular targeted therapy in TSCC. CAL27 and SCC15 cells were treated with different concentrations of EGCG for 24 h. Cell proliferation was determined using Cell-Counting Kit-8 and EdU assays. Cell apoptosis was evaluated by flow cytometry. Cell migration and invasion were measured using scratch and Transwell assays, respectively. Furthermore, protein levels of associated target genes were detected using a western blot assay. It was demonstrated that EGCG affected biological behaviors of CAL27 and SCC15 cells in concentration- and time-dependent manners. In addition, EGCG decreased the protein levels of TAZ, LATS1, MOB1 and JNK. Overexpression of TAZ alleviated the effect of EGCG on CAL27 cells. Furthermore, the combination of EGCG and simvastatin inhibited the proliferation, migration and invasion, and promoted apoptosis significantly compared with single treatment in CAL27 cells. The results of the present study suggested that EGCG affects proliferation, apoptosis, migration and invasion of TSCC through the Hippo-TAZ signaling pathway.

Biological activities and possible dental application of three major groups of polyphenols

The present article reviewed the biological activities and possible dental application of three major polyphenols, i.e., lignin-carbohydrate complexes, tannins, and flavonoids, citing mostly our in vitro studies together with those from other groups. All these polyphenols showed much lower tumor-selective cytotoxicity against oral squamous cell carcinoma cells vs. normal oral cells (gingival fibroblast, pulp cell, periodontal ligament fibroblast), in comparison to popular chemotherapeutic antitumor drugs. Several compounds showing higher tumor-selectivity did not induce internucleosomal DNA fragmentation, a biochemical hallmark of apoptosis, in oral carcinoma cell lines. Lignin-carbohydrate complex protected the cells from the cytopathic effects of HIV infection and UV irradiation more efficiently than other polyphenols. Limited digestion of lignin-carbohydrate complex suggests that the lignin moiety is involved in the prominent anti-HIV activity, whereas the carbohydrate moiety may function in immunopotentiating activity through a cell surface receptor. Alkaline extract of plant leaf, which contains higher amounts of lignin-carbohydrate complex, showed potent anti-inflammatory action against IL-1β-stimulated human gingival fibroblasts. Local application of lignin-carbohydrate complex through oral mucosa is recommended, considering its poor intestinal absorption.

Protective effect of berberine on expression pattern of apoptotic, cell proliferative, inflammatory and angiogenic markers during 7,12-dimethylbenz(a)anthracene induced hamster buccal pouch carcinogenesis

Investigation of expression pattern of molecular markers in oral epithelial tissues would help to assess the cell differentiation and proliferation as well as early diagnosis of precancerous and cancerous lesions of the oral cavity. Aim of the present study was to investigate the protective effect of berberine on expression pattern of apoptotic, cell proliferative, inflammatory and angiogenic markers during 7,12-dimethylbenz(a)anthracene (DMBA) induced hamster buccal pouch carcinogenesis. Immunohistochemical staining [p53, Bcl-2, Bax, Proliferating Cell Nuclear Antigen (PCNA) and Vascular Endothelial Growth Factor (VEGF)], Enzyme Linked Immuno Sorbent Assay (ELISA) [c-fos, COX-2, caspase-3 and -9] and Real-Time PCR [Cyclin D1 and NFkappaB] were utilized to assess the expression pattern of molecular markers in DMBA induced hamster buccal pouch carcinogenesis. Over expression of mutant p53, PCNA, Bcl-2 and VEGF were noticed in hamsters treated with DMBA alone. Decreased expression of Bax protein was noticed in hamsters treated with DMBA alone. Increased expression of C-fos, COX-2, NFkappaB and Cyclin D1 and decreased activities of caspase-3 and -9 were also noticed in hamsters treated with DMBA alone. Oral administration ofberberine at a dose of 75 mg kg(-1) b.w. brought back the expression of above mentioned molecular markers to near normal pattern in hamsters treated with DMBA. The present results thus suggest that berberine has potent anti-inflammatory, anti-angiogenic, anti-cell proliferative and apoptosis inducing properties in DMBA induced oral carcinogenesis.