Aberrations in the mismatch repair genes and the clinical impact on oesophageal squamous carcinomas from a high incidence area in South Africa

Abstract

Aims: To investigate the incidence of genetic aberrations in the DNA repair genes in a cohort of oesophageal cancers. Methods: One hundred oesophagectomy samples of squamous cell carcinoma were studied. Normal and tumour DNA were isolated using a standard phenol/chloroform extraction procedure. Six recommended microsatellite loci with high informativity were analysed. The following markers were used: D2S123 (2p), D3S659 (3p), D3S1255 (3p), Bat 25 (4q), Bat 26 (2p), and Bat 40 (1p). The results were analysed using software attached to an automated DNA sequencer. The molecular data were then correlated with clinicopathological parameters. Results: The incidence of microsatellite instability and loss of heterozygosity was very low. There was no significant correlation between the clinicopathological and molecular data. However, D2S123 genetic abnormalities were seen more frequently in both moderately and well differentiated tumours than in poorly differentiated tumours (p = 0.033). Follow up data were available for only 67 of the 100 patients. Fifty patients were alive and 17 patients had died. Conclusion: Low frequencies of genetic aberrations in these mismatch repair loci are found in squamous carcinomas of the oesophagus from a high incidence area in South Africa. O esophageal cancer is the most common malignancy in black South African men, accounting for 14.3% of all cancers in South Africa.1 Over and above the various environmental factors that impact on the development of cancer in general, great advances have been made during the past decade in our understanding of the molecular mechanisms that occur in the transition from normal mucosa, through dysplasia, and finally to carcinoma.2-4 Several studies have revealed that an accumulation of genetic alterations gives rise to cancer. Furthermore, microsatellite instability (MSI) and loss of heterozygosity (LOH) at highly informative genetic loci at which tumour suppressor genes and oncogenes are located are thought to play a role in carcinogenesis. [5][6][7][8][9][10] Genes investigated in recent studies include p53, Rb, DCC, APC, and MCC. 11 We recently showed that the occurrence of MSI in South African squamous carcinomas of the oesophagus was similar to other high incidence areas. ''The mismatch repair genes play an important role in ensuring that errors occurring during DNA synthesis are corrected'' However, very little is known about the status of the mismatch repair genes and their impact on oesophageal cancer. The mismatch repair genes play an important role in ensuring that errors occurring during DNA synthesis are corrected. These genes were initially identified in bacterial systems and mutations in DNA mismatch repair genes have been associated with hereditary non-polyposis colorectal cancer.12-14 Five human DNA mismatch repair genes have been identified, which when mutated cause susceptibility to both sporadic and hereditary non-polyposis colorectal cancer. Mutational inactivation of both copies of a mismatch repair gene results in a profound repair de...

The promise of PD-1 inhibitors in gastro-esophageal cancers: microsatellite instability vs. PD-L1

“…MSI has been less well studied in ESCC, although it has been detected in a subset of patients (110)(111)(112). Differences in the precise definition of MSI/MMR and test methods may account for some of these reported incidence differences (108).…”

Aberrant Methylation of Different DNA Repair Genes Demonstrates Distinct Prognostic Value for Esophageal Cancer

“…Esophageal cancer with poor survival rate is the eighth most common cancer in the world [1]. Esophageal squamous cell carcinoma (ESCC) is the predominant type of esophageal cancers worldwide, comprising almost 95% of cases.…”

Hypermethylation-modulated down-regulation of CDH1 expression contributes to the progression of esophageal cancer

“…It ranks eighth in order of occurrence worldwide and sixth as the leading cause of death (4,5). china has the highest Ec incidence and mortality rates in the world (1,2,5). Among new cases of Ec in the world, china accounts for 52.8% (3,6).…”

“…In china, it ranks as the fourth and third cause of death in urban and rural areas, respectively (1,2,6,7). Areas of high incidence for Ec in china include the regions of the Taihang Mountains in northern china, the dabie Mountains, northern Sichuan, northern Jiangsu, the southeast coastal areas of the border of Fujian and Guangdong, the inhabited areas of Xinjiang Kazaks, including the ci and She counties of Hebei Province, Lin county of Henan Province, and Yangcheng county in Shanxi Province, which exhibit 5 times the national average incidence and 10 times the world average incidence (1,2,6,7). Ec development shows similarities to other tumors, which implies the involvement of multiple factors, multiple genetic changes, and a multistage development process (8,9).…”

“…Esophageal carcinoma (Ec) is a frequently occurring carcinoma in humans that is characterized by a high degree of malignancy, fast metastasis, poor post-operative quality of life, and significant regional differences in incidence (1)(2)(3). It ranks eighth in order of occurrence worldwide and sixth as the leading cause of death (4,5).…”