Genetic and expression alterations in association with the sarcomatous change of cholangiocarcinoma cells

Cholangiocarcinoma (CC) is an intrahepatic bile duct carcinoma with a high mortality rate and a poor prognosis. Sarcomatous change/epithelial mesenchymal transition (EMT) of CC frequently leads to aggressive intrahepatic spread and metastasis. The aim of this study was to identify the genetic alterations and gene expression pattern that might be associated with the sarcomatous change in CC. Previously, we established 4 human CC cell lines (SCK, JCK1, Cho-CK, and Choi-CK). In the present study, we characterized a typical sarcomatoid phenotype of SCK, and classified the other cell lines according to tumor cell differentiation (a poorly differentiated JCK, a moderately differentiated Cho-CK, and a well differentiated Choi-CK cells), both morphologically and immunocytologically. We further analyzed the genetic alterations of two tumor suppressor genes (p53 and FHIT) and the expression of Fas/FasL gene, well known CC-related receptor and its ligand, in these four CC cell lines. The deletion mutation of p53 was found in the sarcomatoid SCK cells. These cells expressed much less Fas/FasL mRNAs than did the other ordinary CC cells. We further characterize the gene expression pattern that is involved in the sarcomatous progression of CC, using cDNA microarrays that contained 18,688 genes. Comparison of the expression patterns between the sarcomatoid SCK cells and the differentiated Choi-CK cells enabled us to identify 260 genes and 247 genes that were significantly over-expressed and under-expressed, respectively. Northern blotting of the 14 randomly selected genes verified the microarray data, including the differential expressions of the LGALS1, TGFBI, CES1, LDHB, UCHL1, ASPH, VDAC1, VIL2, CCND2, S100P, CALB1, MAL2, GPX1, and ANXA8 mRNAs. Immunohistochemistry also revealed in part the differential expressions of these gene proteins. These results suggest that those genetic and gene expression alterations may be relevant to the sarcomatous change/EMT in CC cells.

Estudio de patrones de metilación génica en tumores del tubo digestivo / Gene methylation patterns in digestive tumors

Background: The loss of tumor suppresor gene function damages the defensive mechanisms that protect the indemnity of genetic material. Promoter gene methylation is one of the inactivation mechanisms of suppressor genes. Aim: To study the methylation pattern of a group of genes in biopsy samples of gastrointestinal tumors. Material and methods: Forty eight gastric, 25 gallbladder, 24 colon and 6 pancreas cancer biopsy samples were randomly selected. The methylation pattern of CDH1, FHIT, CDKN2A, APC and MLH1 genes, was studied using a specific polymerase chain reaction test for methylation. Demographic, morphological and follow up variables of patients bearing the tumors were also analyzed. Results: The general methylation frequency of CDH1, FHIT, CDKN2A, APC and MLH1 genes was 64.1, 56, 39.8, 18.1 and 34 percent respectively. In gastric cancer samples there was a correlation between APC gene methylation and well differentiated tumors; between CDH1 methylation and Lauren diffuse type and the presence of three or more metastasic lymph nodes; between FHIT, CDKN2A and CDH1 gene methylation and male gender. In ¡ess differentiated gallbladder tumors, the frequency of CDH1 methylation was higher. There was a tendency towards a lower survival in colon and gastric cancer when MLH1 (p =0.07) y CDKN2A (p= 0.06) were methylated, respectively. Conclusions: An abnormal methylation pattern was associated with morphological features in gastric and gallbladder cancer and with a tendency towards a lower survival in colon and gastric cancer.

Patrón de metilación génico en el cáncer de mama / Promoter methylation profile in breast cancer

BACKGROUND: Genomic DNA methylation, mutations and allelic deletions explain the inactivation of genes involved in cell proliferation and cell cycle control mechanisms. AIM: To analyze the methylation pattern of important genes related to different carcinogenic mechanisms in patients with breast cancer and the relationship with its biological behavior. MATERIAL AND METHODS: Seventy fresh-frozen breast cancer samples were selected. The methylation specific PCR (MSP) test was used to analyze promoter methylation status for genes CDKN2A (p16), hMLH1, APC, CDH1 (Cadherin E) and FHIT. RESULTS: We found methylation in at least one of the genes studied in 88% of cases and in 3 or more genes in 40.5% of cases. The frequencies of promoter hypermethylation of CDKN2A, hMLH1, APC, CDH1 and FHT were 41.4%, 11.4%, 52.9%, 70% and 42.9%, respectively. We found a relationship between CDKN2A methylatlon and better survival (p=0.002). CDH1 methylation and poor histological differentiation (p=0.007), hMLH1 methylation and non-Mapuche ethnicity (p=-0.03), APC methylation and larger tumor size (p<0.05), FHIT methylatton and lack of estrogen rectptor IHC expression (p<0.05). CONCLUSIONS: The high frequency of promoter methylation in patients with breast cancer confirms its role in breast carcinogenesis. The finding of alterations in the methylation pattern of genes studied and its association with prognostic factors is a helpful tool in the search of new criteria for clinical and therapeutic decision making.