| Lung cancer has been the most common cause of cancer-related death worldwide. Current investigations in the field of cancer research intensively focus upon the"cancer stem cell"or"tumor initial cell."Correspondingly, the concept of a cancer stem cell is very appealing; it is a cell that can perform the self-renewal, proliferation, differentiation, and stay in quiescence at the most time. Hence the fraction is the original cell initialing the tumorigensis process and must be killed if the tumor is to be controlled by treatment. One selection technique applied for sorting these tumor cells in the prepared suspension is based on the presence or absence of surface molecular markers. Thus, it is necessary to utilize specific markers to detect and isolate CSCs from among the innumerable cancer cells. While CD133 was initially considered only a stem cell marker in the hematopoietic system and the nervous system, the membrane antigen has also been found to identify tumorigenic cells in some solid tumors. In this study, we investigated human lung cancer cell lines: A549, H157, H226, Calu-1, H292 and H446. The results of the real-time PCR after chemotherapy drug selecting and the fluorescence-activated analysis showed that CD133 only worked in small cell lung cancer line H446. The sorted CD133-positive subset presented stem-cell-like features including self-renewal, differentiation, proliferation and tumorigenic capacity in subsequent assays. Furthermore, a proportion of CD133-positive cells had a tendency to maintain stable to quiescent status, which may explain the controversies rising from previous studies. Therefore, the CD133-positive subset should provide an enriched source of tumor-initial cells in H446 with their particular capacities. Moreover, the antigen could be used as an investigative marker of the tumorigenic process, and an effective treatment for small cell lung cancer. The objective of this study was to investigate epidermal growth factor receptor expression and to explore its significance in thymoma. We reviewed twenty thymic hyperplasia patients and sixty-three thymoma patients and performed immunohistochemical assays to evaluate epidermal growth factor receptor expression. The correlations between epidermal growth factor receptor status and some parameters such as age, sex, myasthenia gravis morbidity, tumor size, pathological classification and clinical stage were analyzed. Forty-five thymoma cases were followed continuously for 5 years, and several potential factors, including pathological classification, clinical stage, epidermal growth factor receptor status, completely resection and tumor size were assessed by multivariate analyses. The relapse-free time was calculated for twenty-one completely resected stage II thymoma cases without radiotherapy. The positive rates of epidermal growth factor receptor versus the clinicopathological parameters were calculated as follows: pathologically, A: 33.3 %; AB: 25%; B1: 42.8%; B2: 60 %; B3: 84.6 %; clinically, stage I: 27.8 %, stage II: 53.8 %, stage III: 82.4 %, stage IV: 100 %. Correlations between the expression of epidermal growth factor receptor and clinicopathological parameters were assessed. We failed to prove that epidermal growth factor receptor was an independent prognostic factor of thymoma; however, the presence of epidermal growth factor receptor was correlated to a reduction in relapse-free time in resected stage II cases of thymoma.Conclusions: The epidermal growth factor receptor overexpression correlated to a high-class pathological diagnosis or an advanced clinical stage in thymoma. Although the prognostic value of epidermal growth factor receptor expression could not be confirmed, the results obtained in the relapse study indicated that the epidermal growth factor receptor played an important role in the progression of thymoma.
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