Fas ligand expression in colon cancer:A possible mechanism of tumor immune privilege

AIM: To detect the expression of Fas ligand (FasL) in colon cancer tissues and cell lines and analyze the function of FasL-expressing colon cancer cells in inducing Fas-sensitive T lymphocyte apoptosis. METHODS: Ninety surgically resected colon cancer tissues and 15 hepatic metastasis specimens were investigatedby immunohistochemical method with normal colon mucosa and colon adenoma as control. The relationship between FasL expression and pathologic features was also analyzed.FasL expression of 4 colon cancer cell lines, SW620, Lovo, LS-174T and SW1116, were detected by Western blotting assay. The function of FasL expressed on colon cancer cells was determined by coculture assay with Jurkat T lymphocytes, the apoptotic rate of which was detectedby flow cytometry assay.RESULTS: Fifty-six (62.22%) cases of all the 90 colon cancer tissues and all (100%) the liver metastasis specimens expressed FasL, significantly higher than normal colon mucosa and colonic adenoma. Higher expression of FasL was found in more advanced stage of colon cancer and in cancer tissues with lymphatic or hepatic metastasis.All the colon cancer cell lines were found to express FasL.After coculture with the SW1116 cells for 24 h with an effector: target ratio 10:1, the rate of apoptosis of Jurkat cells rose from 1.9% to 21.0%.CONCLUSION: The expression of FasL is upregulated in colon cancer and the functionally expressed FasL can induce apoptosis of Fas-expressing T lymphocytes.

Diagnosis and Surgical Treatment Parathyroid Adenoma （24 Case Report）

OBJECTIVE To summarize the experience in diagnosing and treating parathyroid adenoma.METHODS Twenty-four patients were diagnosed with parathyroid adenoma and received parathyroidectomy in our hospital. Sixteen of them presented with hyperparathyroidism. The patients received ultrasounography, CT or ^99mTc-MIBI to locate the tumor site. Serum concentrations of PTH and calcium were checked before the operation. All operations were performed under general anesthesia. The adenomas were resected and the four glands explored.RESULTS All of the patients were cured and there was no mortality in our group. The symptoms of hyperparathyroidism remitted to various degrees after the operation. PTH dropped to the normal range 2 days after operation.Serum calcium concentrations declined to different levels from the first day after operation. Seven patients developed hypocalcemia post-operation but recovered by injection of calcium gluconate. Only one of the patients with parathyroid adenoma recurred 2 years after the operation and was found to have malignancy of the parathyroid adenoma.CONCLUSION Not all the patients with parathyroid adenoma had clinical manifestations. The CT and ^99mTc-MIBI were more accurate than ultrasounography in locating the adenoma. The four glands should be explored during the operation. Protecting the recurrent laryngeal nerve from being injuried and maintaning secure hemastasis were most important.