RASSF2 can bind directly to K-Ras and function as a negative effector of Ras protein. RASSF2A is the only isoform of RASSF2 that contains CpG islands in its promoter and it has been reported to be inactivated by its promoter methylation in several human cancers. In the present study, we investigated the correlation of RASSF2A expression with its promoter methylation in nasopharyngeal carcinoma (NPC). Expression of RASSF2A was downregulated in 80% (4/5) of NPC cell lines. Decreased RASSF2A expression was also observed in NPC primary tumors compared with normal nasopharyngeal epithelia. Promoter methylation of RASSF2A could be detected in all the RASSF2A-silenced cell lines (4/5) of the NPC cell lines and 50.9% (27/53) of primary tumors, but not in any of the normal epithelia. RASSF2A-methylated cases showed a significantly lower level of RASSF2A expression than unmethylated cases. Loss of RASSF2A expression can be greatly restored by the methyltransferase inhibitor 5-aza-dC in NPC cell lines. In addition, patients with methylated RASSF2A presented a higher frequency of lymph node metastasis (p < 0.05). Ectopic expression of RASSF2A in RASSF2A-silenced and -methylated NPC cell line CNE2 shows that RASSF2A could inhibit cell cycle progression, colony formation and cell migration, which provided further evidence that RASSF2A is a candidate tumor suppressor gene. In conclusion, RASSF2A, a candidate tumor suppressor gene (TSG), is frequently inactivated by its promoter methylation and this aberrant methylation correlates with lymph node metastasis in NPC. ' 2006 Wiley-Liss, Inc.

Radiation-induced sarcoma in the head and neck (RISHN) is a rare condition whose clinical presentation and management remain difficult because of its low incidence. In this retrospective study, we analyzed the symptoms, diagnosis, and the treatment of 16,634 patients with head and neck disease, who received radiotherapy between 1960 and 2010 at the Affiliated Tumor Hospital and its predecessor, Guangxi Medical University, China. Among these patients, 16 with a first tumor of nasopharyngeal carcinoma (NPC) and 1 with squamous carcinoma of the tongue met the criteria of RISHN in the head and neck. Our epidemiological data showed that the incidence of RISHN rose from 0.06 to 0.17% from 1960 to 2010; the 3-year overall survival rate was 19.1%, and 3-year disease-free survival rate was 11.1%. The mean latency (SD) period was 93.2 (33) months. Based on the experiences at our institution, we suggest that RISHN is a rare complication after radiotherapy for head and neck tumors, especially NPC. Owing to its low incidence, it should not be a major factor affecting decisions about radiotherapy. Nevertheless, there may be a possibility of increasing incidence of RISHN after radiotherapy of NPC, as shown in our epidemiological results. Given the poor prognosis of RISHN, this possibility should be taken into serious consideration before determination of high-dose radiotherapy for patients with NPC and other head and neck tumors.

We report the emerging role of microRNA (miRNA) deregulation associated with activation of an oncogene SOX4 (a member of the SRY-related HMG-box) in esophageal carcinoma. Paired esophageal cancer and adjacent non-tumor tissues were obtained from 42 patients who underwent primary surgical resection for esophageal cancer. Experiments such as real-time PCR, western blot analysis, luciferase-reporter assay, cell proliferation and colony formation assays, in vitro migration and invasion assays, and a wound-healing assay were performed to determine the effects of miR-129-2. We found that SOX4 expression was elevated (P<0.005) in esophageal tumors (n=42) when compared with its expression in the controls (n=42). Compared with the normal esophageal tissues, the expression of miR-129-2 was downregulated in 27 of 31 primary esophageal tumors, while the expression of SOX4 was upregulated (P<0.001). Restoration of miR-129-2 by transfection with an miRNA expression plasmid led to a decrease in SOX4 expression, which was accompanied by reduced migration and proliferation of the cancer cells. These results suggest that aberrant expression of SOX4 is associated with repression of miR-129-2, and restoration of miR-129-2 suppresses the migration and proliferation of esophageal cancer cells. Our results demonstrated that the deregulation of miR-129-2 leads to aberrant SOX4 expression, presenting a new paradigm in which the restoration of miRNA suppresses its oncogenic target in esophageal cancer.