Chunnan Li

Expression of vascular endothelial growth factor A, B, C, and D in oral squamous cell carcinoma

Vascular endothelial growth factor (VEGF) A is known to play an important role in tumor angiogenesis. The additional members of the VEGF family, VEGF B, C and D have been discovered. VEGF C and D show some selectivity toward lymphatic endothelial cells. However, whether VEGF family members play a role in tumor angiogenesis and lymph node metastasis is largely unknown. The aim of the present study was to explore the role of VEGF family members in oral squamous cell carcinoma (OSCC). We evaluated the expression of VEGF family members by immunohistochemistry, reverse transcription-polymerase chain reaction, and western blotting. All VEGF members were expressed at different levels in OSCC. Immunohistological analysis of VEGF family members expression and microvessel density revealed a correlation between VEGF A and B expression and tumor angiogenesis. Although VEGF A and B expression were detected in both node-positive and node-negative OSCC, VEGF C and D expression was detected frequently in node-positive tumors compared to node-negative tumors. These findings suggest a possible relationship between the expression level of VEGF C and/or D and development of lymphatic tumor spread.

Enhancement of tumor radioresponse by combined treatment with gefitinib (Iressa, ZD1839), an epidermal growth factor receptor tyrosine kinase inhibitor, is accompanied by inhibition of DNA damage repair and cell growth in oral cancer.

Molecular blockade of EGFR with either an EGFR MAb or an EGFR TKI enhances the radiosensitivity of human SCCs. In the present study, we investigated whether treatment with the EGFR TKI gefitinib (Iressa, ZD1839) improves the response to radiotherapy in the OSCC cell lines HSC2 and HSC3. We examined potential mechanisms that may contribute to the enhanced radiation response induced by gefitinib. Growth inhibition was observed in vitro with radiation or gefitinib. A cooperative antiproliferative effect was obtained when cancer cells were treated with radiation followed by gefitinib. Cells treated with a combination of radiation and gefitinib arrested in G1 and G2–M phases, with a decrease in the S‐phase population. While radiation alone did not significantly affect MEK1/2 and p38 MAPK autophosphorylation, the combination of gefitinib and radiation completely inhibited the downstream signaling of EGFR. Results from DNA damage repair analysis in cultured OSCC cells demonstrated that gefitinib had a strong inhibitory effect on DNA‐PKc pathways after radiation. Tumor xenograft studies demonstrated that the combination of gefitinib and radiation caused growth inhibition and tumor regression of well‐established OSCC tumors in athymic mice; tumor volume was reduced from 1,008.2 to 231.4 mm3 in HSC2 cells (p < 0.01) and from 284.2 to 12.4 mm3 in HSC3 cells (p < 0.01). Immunohistochemical analysis of OSCC xenografts revealed that gefitinib caused a striking decrease in tumor cell proliferation when combined with radiotherapy. Overall, we conclude that gefitinib enhances tumor radioresponse by multiple mechanisms that may involve antiproliferative growth inhibition and effects on DNA repair after exposure to radiation.

Up-regulation of DNA-dependent protein kinase correlates with radiation resistance in oral squamous cell carcinoma.

DNA‐PK is a nuclear protein with serine/threonine kinase activity and forms a complex consisting of the DNA‐PKcs and a heterodimer of Ku70 and Ku80 proteins. Recent laboratory experiments have demonstrated that the DNA‐PK complex formation is one of the major pathways by which mammalian cells respond to DNA double‐strand breaks induced by ionizing radiation. In this study, we evaluated the relationship between expression levels of DNA‐PKcs, Ku70 and Ku80 proteins and radiation sensitivity in oral squamous cell carcinoma (OSCC) cell lines and in OSCC patients treated with preoperative radiation therapy. The OSCC cell lines greatly differed in their response to irradiation, as assessed by a standard colony formation assay. However, the expression levels of the DNA‐PK complex proteins were all similar, and there was no association between the magnitude of their expression and the tumor radiation sensitivity. Expression of DNA‐PK complex proteins increased after radiation treatment, and the increased values correlated with the tumor radiation resistance. Expression of DNA‐PKcs and Ku70 after irradiation was increased in the surviving cells of OSCC tissues irradiated preoperatively. These results suggest that up‐regulation of DNA‐PK complex protein, especially DNA‐PKcs, after radiation treatment correlates to radiation resistance. DNA‐PKcs might be a molecular target for a novel radiation sensitization therapy of OSCC.

Growth-regulated oncogene-1 expression is associated with angiogenesis and lymph node metastasis in human oral cancer.

Growth-regulated oncogene-1 (GRO-1) is an autocrine growth factor in melanoma and is a member of the CXC family of chemokines which promote chemotaxis of granulocytes and endothelia through binding to CXC receptor 2. A previous article noted that GRO-1 was upregulated in oral cancer using a genome-wide microarray approach. We have examined the expression of GRO-1 in 9 oral squamous cell carcinoma (OSCC) cell lines and 94 OSCC specimens. Using real-time quantitative polymerase chain reaction analyses, GRO-1 expressions were varied in OSCC cell lines. Of the 94 OSCC specimens, 37 (39.4%) showed GRO-1 cytoplasmic immunostaining, and microvessel density revealed a correlation between GRO-1 expression and tumor angiogenesis. GRO-1 expression was also associated with leukocyte infiltration, and lymph node metastasis. These findings suggest a possible relationship between the expression level of GRO-1 and tumor progression.

Potential anti-osteoporotic effects of herbal extracts on osteoclasts, osteoblasts and chondrocytes in vitro

BackgroundOsteoporosis (OP) is one of the most serious diseases in the modern world, and OP patients frequently suffer from fragility fractures in the hip, spine and wrist, resulting in a limited quality of life. Although bisphosphonates (BPs) are the most effective class of anti-bone-resorptive drugs currently available and the most commonly prescribed for the clinical treatment of OP, they are known to cause serious side effects such as bisphosphonate-related osteonecrosis of the jaw. Novel therapeutic materials that can replace the use of BPs have therefore been developed.MethodsWe commenced an institutional collaborative project in which candidates of herbal extracts were selected from more than 400 bioactive herbal products for their potential therapeutic effects not only in OP, but also in oral and skeletal diseases. In the present study, we report on 3 Chinese medical herbal extracts from the root barks of Melia azedarach, Corydalis turtschaninovii, and Cynanchum atratum.ResultsAll of these extracts inhibited osteoclast proliferation and induced apoptosis by up-regulation of caspase activity and increase of mitochondrial pro-apoptotic proteins expression. Furthermore, the extracts enhanced differentiation, but did not affect proliferation of both osteoblasts and chondrocytes. The osteo-inducible effect was also observed in cultured primary bone marrow cells.ConclusionsAlthough these extracts have been utilized in traditional Chinese medicine for hundreds of years, there are no reports to our knowledge, on their therapeutic effects in OP. In this study, we elucidate the potency of these herbal extracts as novel candidates for OP therapy.

Root bark extracts of Juncus effusus and Paeonia suffruticosa protect salivary gland acinar cells from apoptotic cell death induced by cis-platinum (II) diammine dichloride

Cis-platinum (II) diammine dichloride (CDDP) is a platinum-based anticancer agent, and is often used for chemotherapy for malignant tumors, albeit CDDP has serious side-effects, including xerostomia (dry mouth). Since patients with xerostomia have reduced quality of life, it is urgent and important to identify nontoxic and natural agents capable of reducing the adverse effect of chemotherapy on salivary gland function. Therefore, we commenced an institutional collaborative project in which candidates of herbal extracts were selected from more than 400 bioactive herbal products for their potential therapeutic effects not only on xerostomia, but also on oral diseases. In the present study, we report on two Chinese medical herbal extracts from the root barks of Juncus effusus and Paeonia suffruticosa. The two extracts showed a protective effect in NS-SV-Ac cells from the cytotoxicity and apoptosis caused by CDDP. The effect was dependent on the p53 pathway, protein kinase B/Akt 1 and mitochondrial apoptosis-related proteins (i.e. Bcl-2 and Bax), but was not dependent on nuclear factor κB. Notably, the apoptosis-protective effect of the extracts was not observed in adenocystic carcinoma cell lines. Although these extracts have been utilized in traditional Chinese medicine for hundreds of years, there are no reports to our knowledge, on their therapeutic effects on xerostomia. Thus, in the present study, we elucidated the potency of these herbal extracts as novel candidates for xerostomia to improve the quality of life of patients undergoing chemotherapy.

HER2/neu Expression in Oral Squamous Cell Carcinoma

Abstract Objective: To evaluate the expression of HER2/neu in oral squamous cell carcinoma with a view to determining the usefulness of molecular target therapy by anti-HER2 antibody. Patients and Methods: Oral squamous cell carcinoma cell lines and 69 clinical tumour samples were tested using enzyme-linked immunosorbent assay and immunohistochemistry. Positive and negative controls were utilised. Results: Expression of HER2/neu in oral squamous cell carcinoma cell lines was low. Overexpression was not observed in the clinical samples. Conclusion: Low prevalence of expression of HER2/neu in oral squamous cell carcinoma limits the likely utility of herceptin therapy.