Seong Doo Hong

Silymarin and its active component silibinin act as novel therapeutic alternatives for salivary gland cancer by targeting the ERK1/2-Bim signaling cascade

PurposeApproximately 20% of all salivary gland cancer patients who are treated with current treatment modalities will ultimately develop metastases. Its most common form, mucoepidermoid carcinoma (MEC) is a highly aggressive tumor with an overall 5-year survival rate of ~30%. Until now, several chemotherapeutic drugs have been tested for the treatment of salivary gland tumors, but the results have been disappointing and the drugs often cause unwanted side effects. Therefore, several recent studies have focused on the potential of alternative and/or complementary therapeutic options, including the use of silymarin.MethodsThe effects of silymarin and its active component silibinin on salivary gland cancer-derived MC3 and HN22 cells and their underlying molecular mechanisms were examined using trypan blue exclusion, 4′-6-diamidino-2-phenylindole (DAPI) staining, Live/Dead, Annexin V/PI staining, mitochondrial membrane potential (ΔΨm) measurement, quantitative RT-PCR, soft agar colony formation and Western blotting analyses.ResultsWe found that silymarin and silibinin dramatically increased the expression of the pro-apoptotic protein Bim in a concentration- and time-dependent manner and, concomitantly, induced apoptosis in MC3 and HN22 cells. We also found that ERK1/2 signaling inhibition successfully sensitized these cells to the apoptotic effects of silymarin and silibinin, which indicates that the ERK1/2 signaling pathway may act as an upstream regulator that modulates the silymarin/silibinin-induced Bim signaling pathway.ConclusionsTaken together, we conclude that ERK1/2 signaling pathway inhibition by silymarin and silibinin increases the expression of the pro-apoptotic Bcl-2 family member Bim which, subsequently, induces mitochondria-mediated apoptosis in salivary gland cancer-derived cells.

Nitidine chloride acts as an apoptosis inducer in human oral cancer cells and a nude mouse xenograft model via inhibition of STAT3

Nitidine chloride (NC) is a natural alkaloid compound derived from the plant Zanthoxylum nitidum and is known for its therapeutic anticancer potential. In this study, we investigated the effects of NC on growth and signaling pathways in human oral cancer cell lines and a tumor xenograft model. The apoptotic effects and related molecular targets of NC on human oral cancer were investigated using trypan blue exclusion assay, DAPI staining, Live/Dead assay, Western blotting, Immunohistochemistry/Immunofluorescence and a nude mouse tumor xenograft. NC decreased cell viability in both HSC3 and HSC4 cell lines; further analysis demonstrated that cell viability was reduced via apoptosis. STAT3 was hyper-phosphorylated in human oral squamous cell carcinoma (OSCC) compared with normal oral mucosa (NOM) and dephosphorylation of STAT3 by the potent STAT3 inhibitor, cryptotanshinone or NC decreased cell viability and induced apoptosis. NC also suppressed cell viability and induced apoptosis accompanied by dephosphorylating STAT3 in four other oral cancer cell lines. In a tumor xenograft model bearing HSC3 cell tumors, NC suppressed tumor growth and induced apoptosis by regulating STAT3 signaling without liver or kidney toxicity. Our findings suggest that NC is a promising chemotherapeutic candidate against human oral cancer.

Staging significance of bone invasion in small-sized (4 cm or less) oral squamous cell carcinoma as defined by the American Joint Committee on Cancer

OBJECTIVESnThe staging significance of bone invasion is controversial in oral squamous cell carcinoma (OSCC) cases with tumors measuring 4cm or less according to the American Joint Committee on Cancer (AJCC). Our aim was to retrospectively examine a large group of patients with OSCC to determine the staging significance of bone invasion.nnnMATERIALS AND METHODSnThree hundred and twenty-three patients with primary OSCC were classified based on tumor size. Bone invasion was categorized as absent, one side bone, and both buccal and lingual bones, and analyzed for association with disease progression. Regional lymph node metastasis (N), perineural invasion, vascular invasion, surgical margin involvement, and adjuvant treatment were also analyzed.nnnRESULTSnIn all OSCC cases, bone invasion (p=0.007) with stage N, perineural invasion, and surgical margin involvement were significant independent prognostic factors of disease progression. However, in OSCC cases with tumors measuring 4cm or less, bone invasion was not significantly associated with disease progression. Nevertheless, invasion of both buccal and lingual bones was significantly associated with disease progression (p=0.03). In multivariate analysis, both buccal and lingual bone invasion (p=0.04; hazard ratio=3.4; 95% confidence interval, 1.0-11.0), stage N2, and perineural invasion were also independent prognostic factors.nnnCONCLUSIONnAlthough OSCC bone invasion was an independent prognostic factor, bone invasion in small OSCC was not. However, small OSCC with both buccal and lingual bone invasion had a significantly worse prognosis. The AJCC T system is of limited prognostic value for small OSCC with bone invasion. But other elements should be examined before a modification can be accepted.

Apoptosis induced by methanol extract of Potentilla discolor in human mucoepidermoid carcinoma cells through STAT3/PUMA signaling axis

Potentilla discolor has been used in traditional Chinese medicine for the treatment of hyperglycemia. However, the potential role of Potentilla discolor against cancer and its mode of action remain to be fully elucidated. The present study explored the apoptotic effect of methanol extract of Potentilla discolor (MEPD) in human mucoepidermoid carcinoma (MEC) cell lines of salivary glands. MEPD markedly suppressed the growth and induced apoptotic cell death in MC3 and YD15 cells. MEPD treatment significantly upregulated the expression of PUMA and reduced STAT3 phosphorylation. Overexpression of STAT3 partially recovered the growth of MEC cells inhibited by MEPD. In addition, dephosphorylation of STAT3 by cryptotanshinone (a potent STAT3 inhibitor) was sufficient to inhibit the growth of MEC cells and induce apoptosis via affecting PUMA protein. These results suggest that MEPD has a potential anticancer property via the STAT3/PUMA signaling axis in human MEC cells of salivary gland.

Nitidine chloride represses Mcl-1 protein via lysosomal degradation in oral squamous cell carcinoma

BACKGROUNDnWe have shown previously that nitidine chloride (NC) induces apoptosis via inhibition of signal transducer and activator of transcription 3 (STAT3). However, its downstream molecules are not fully understood yet. Here, we report that NC as STAT3 inhibitor downregulates myeloid cell leukemia-1 (Mcl-1) protein in HSC-3 and HSC-4 human oral squamous cell carcinoma (OSCC) cells and a nude mouse tumor xenograft model.nnnMETHODSnThis study investigated the effects of NC on Mcl-1 expression in HSC-3 and HSC-4 cells using Western blotting, RT-PCR, and dual-luciferase assay. Immunohistochemistry was employed to evaluate Mcl-1 expression levels in mouse tumor tissues. Construction of Mcl-1 overexpression vector and transient transfection was done to test the apoptosis of HSC-3 cells.nnnRESULTSnNitidine chloride did not affect either mRNA level or promoter activity of Mcl-1, and the decrease in Mcl-1 protein by NC was caused by lysosome-dependent degradation, but not proteasome-dependent degradation. The overexpression of Mcl-1 protein in OSCC cell lines was sufficient to block the induction of apoptosis. In addition, NC strongly reduced the expression level of Mcl-1 protein compared with other STAT3 inhibitors such as cryptotanshione and S3I-201 in OSCCs.nnnCONCLUSIONSnOur findings suggest that NC triggers apoptosis via lysosome-dependent Mcl-1 protein degradation and could be chosen as a promising chemotherapeutic candidate against human OSCCs.