ABSTRACT
Recent studies have suggested that the RAS protein activator like-1 (RASAL1) is a potential tumor suppressor, which is found to be reduced in certain human cancers. Its downregulation is involved in the progression of malignancies. However, whether or not RASAL1 plays a role in the development of gastric cancer remains to be determined. Our study aimed to clarify the role of RASAL1 in the progression of gastric adenocarcinoma. The expression of RASAL1 in primary gastric adenocarcinoma tissue specimens was determined by immunohistochemistry. The expression of RASAL1 mRNA and protein was detected by RT-PCR and western blotting in gastric adenocarcinoma cell lines with varying differentiation statuses, including well-differentiated MKN-28, moderately differentiated SGC-7901 and poorly differentiated BGC-823, respectively. A normal gastric epithelial cell line, GES-l, was used as the control line. The immunohistochemical results revealed that the expression of the RASAL1 protein was mainly observed in the cytoplasm. Among 50 cases of gastric adenocarcinoma tissues, 12 cases were identified as (-), 23 cases (+), 13 cases (++) and 2 cases (+++). Among 50 cases of normal gastric tissues, 16 cases were (++) and 34 cases (+++). The expression of the RASAL1 protein was found to be decreased in the gastric adenocarcinoma tissue compared with normal gastric tissue (p<0.01). Moreover, in the gastric carcinoma tissues, the expression of RASAL1 was correlated with carcinoma diameter, differentiation grades, invasive depth, lymph node metastasis and TNM. Additionally, the RASAL1 mRNA and proteins were decreased in the three gastric adenocarcinoma cell lines compared with the normal gastric epithelial cell line GES-l. In addition, the downregulation of RASAL1 correlated with the differentiation status of cancer cell lines. Based on the above investigation, we conclude that expression of the RASAL1 gene is decreased in gastric carcinoma tissues and cell lines. The results indicate that RASAL1 may be important in the tumorigenesis and development of gastric carcinoma.
ABSTRACT
OBJECTIVE: To study the natural history of HIV-1 infection among intravenous drug users (IDUs) detected in late 1989 in the study area and the factors related to survival of these IDUs infected with HIV. METHODS: 196 injecting drug users first detected during August and December, 1989 were observed in Ruili county, Yunnan province. Data gathered from the 20-year follow-up program was collected and analyzed retrospectively. RESULTS: After 20 years' follow-up period, 90.3% of the 196 IDUs with HIV infection died, 5.1% of them were still alive, and 4.6% were lost. The crude pre-AIDS mortality rate was 98.1/1000 person-years, and the AIDS mortality rate was 54.9/1000 person-years. Malaria, septicemia were the main causes of death among the natural diseases whereas overdose and accidental causes were the principal causes related to those non-disease deaths. The median survival time from sero-conversion to death was 8.6 years (95%CI: 7.6 - 9.7). The median survival time from sero-conversion to death due to AIDS was 11.3 years (95%CI: 10.3 - 12.8) with the incubation time as around 10.3 years. People older than 30 years at seroconversion and length of drug usage were associated with shorter survival time, with hazards ratios as 1.9 and 0.7, respectively. CONCLUSION: A high pre-AIDS mortality was observed among IDUs. Both the median survival time from sero-conversion to death and the HIV incubation period were shorter than that observed in the developed countries. Age of HIV infection seemed to have a strong effect on survival.
