Presence of microsatellite instability in esophageal squamous cell carcinoma associated with chagasic megaesophagus

AIM

The molecular pathogenesis of esophageal squamous cell carcinoma (ESCC) has been increasingly studied, but there is no report on the role of MSI in ESCC development associated with chagasic megaesophagus (CM).Results/methodology: In four ESCC/CM (4/19) we found microsatellite instability (MSI) alterations (21.1%), being three MSI-L (15.8%) and one MSI-H (5.3%). Four out of 35 ESCC cases showed MSI-L (11.4%) and only one out of 26 CM cases presented MSI-L (3.9%). The MSI-H was observed in an ESCC/CM patient that presents lack of MSH6 immunostaining corroborating deficiency in MMR pathway. Interestingly, the MSI-H ESCC/CM case also presented a deletion the HSP110 poly(T)17 gene.

DISCUSSION/CONCLUSION

Taking together, we concluded that MSI is a rare event in esophageal squamous cell carcinoma, but can be associated with CM.

Lack of microsatellite instability in gastrointestinal stromal tumors

The microsatellite instability (MSI) phenotype may constitute an important biomarker for patient response to immunotherapy, particularly to anti-programmed death-1 inhibitors. MSI is a type of genomic instability caused by a defect in DNA mismatch repair (MMR) proteins, which is present mainly in colorectal cancer and its hereditary form, hereditary nonpolyposis colorectal cancer. Gastrointestinal stromal tumor (GIST) development is associated with activating mutations of KIT proto-oncogene receptor tyrosine kinase (KIT) or platelet-derived growth factor receptor α (PDGFRA), which are oncogenes that predict the response to imatinib mesylate. In addition to KIT/PDGFRA mutations, other molecular alterations are important in GIST development. In GISTs, the characterization of the MSI phenotype is scarce and the results are not consensual. The present study aimed to assess MSI in a series of 79 GISTs. The evaluation of MSI was performed by pentaplex polymerase chain reaction comprising five markers, followed by capillary electrophoresis. The expression of MMR proteins was evaluated by immunohistochemistry. Regarding the KIT/PDGFRA/B-Raf proto-oncogene, serine/threonine kinase molecular profile of the 79 GISTs, 83.6% of the tumors possessed KIT mutations, 10.1% had PDGFRA mutations and 6.3% were triple wild-type. The mutated-PDGFRA cases were associated with gastric location and a lower mitotic index compared with KIT-mutated and wild-types, and these patients were more likely to be alive and without cancer. MSI analysis identified 4 cases with instability in one marker, however, additional evaluation of normal tissue and immunohistochemical staining of MMR proteins confirmed their microsatellite-stable nature. The results of the present study indicated that MSI is not involved in GIST tumorigenesis and, therefore, cannot serve as a biomarker to immunotherapy response in GIST.

MET Is highly expressed in advanced stages of colorectal cancer and indicates worse prognosis and mortality

The aim of the present study was to evaluate by immunohistochemistry the prognostic meaning of the tumor marker MET (hepatocyte growth factor) in patients submitted to surgical resection due to primary colorectal adenocarcinoma.

PATIENTS AND METHODS

A retrospective study was carried out that included 286 consecutive patients with colorectal adenocarcinoma, submitted to surgical resection at Barretos Cancer Hospital, from 1993 to 2002. The histopathological expression of the MET tumor marker was evaluated using an anti-protein monoclonal antibody against MET by the streptavidin-biotin-peroxidase technique. The expression of the tumor marker was semi-quantitative, and the slide samples were independently analyzed by three pathologists unaware of patient clinical and histopathological data.

RESULTS

The tumor marker expression was positive in 236 (79%) out of a total of 286 patients. This expression was statistically significantly different between stages I and IV (p=0.004), for overall survival (p=0.009), and for cancer-related mortality rates (p=0.022). However, no association between the tumor marker and recurrence (p=0.89) or disease-free interval (p=0.91) was observed.

CONCLUSION

MET has shown significant expression at advanced stages of the disease, as well as for overall survival and cancer-related mortality rates demonstrating to be a valuable marker for poor prognosis in colorectal cancer patients.