Esophageal squamous cell carcinomas with DNA replication errors (RER+) are associated with p16/pRb loss and wild-type p53

SALL Proteins; Common and Antagonistic Roles in Cancer

Simple Summary

Transcription factors play essential roles in regulating gene expression, impacting the cell phenotype and function, and in the response of cells to environmental conditions. Alterations in transcription factors, including gene amplification or deletion, point mutations, and expression changes, are implicated in carcinogenesis, cancer progression, metastases, and resistance to cancer treatments. Not surprisingly, transcription factor activity is altered in numerous cancers, representing a unique class of cancer drug targets. This review updates and integrates information on the SALL family of transcription factors, highlighting the synergistic and/or antagonistic functions they perform in various cancer types.

Abstract

SALL proteins are a family of four conserved C2H2 zinc finger transcription factors that play critical roles in organogenesis during embryonic development. They regulate cell proliferation, survival, migration, and stemness; consequently, they are involved in various human genetic disorders and cancer. SALL4 is a well-recognized oncogene; however, SALL1–3 play dual roles depending on the cancer context and stage of the disease. Current reviews of SALLs have focused only on SALL2 or SALL4, lacking an integrated view of the SALL family members in cancer. Here, we update the recent advances of the SALL members in tumor development, cancer progression, and therapy, highlighting the synergistic and/or antagonistic functions they perform in similar cancer contexts. We identified common regulatory mechanisms, targets, and signaling pathways in breast, brain, liver, colon, blood, and HPV-related cancers. In addition, we discuss the potential of the SALL family members as cancer biomarkers and in the cancer cells’ response to therapies. Understanding SALL proteins’ function and relationship will open new cancer biology, clinical research, and therapy perspectives.

Microsatellite alterations in phenotypically normal esophageal squamous epithelium and metaplasia-dysplasia-adenocarcinoma sequence

AIM: To investigate the microsatellite alterations in phenotypically normal esophageal squamous epithelium and metaplasia-dysplasia-adenocarcinoma sequence.

METHODS: Forty-one specimens were obtained from esophageal cancer (EC) patients. Histopathological assessment identified 23 squamous cell carcinomas (SCC) and 18 adenocarcinomas (ADC), including only 8 ADC with Barrett esophageal columnar epithelium (metaplasia) and dysplasia adjacent to ADC. Paraffin-embedded normal squamous epithelium, Barrett esophageal columnar epithelium (metaplasia), dysplasia and esophageal tumor tissues were dissected from the surrounding tissues under microscopic guidance. DNA was extracted using proteinase K digestion buffer, and DNA was diluted at 1:100, 1:1000, 1:5000, 1:10 000 and 1:50 000, respectively. Seven microsatellite markers (D2S123, D3S1616, D3S1300, D5S346, D17S787, D18S58 and BATRII loci) were used in this study. Un-dilution and dilution polymerase chain reactions (PCR) were performed, and microsatellite analysis was carried out.

RESULTS: No statistically significant difference was found in microsatellite instability (MSI) and loss of heterozygosity (LOH) of un-diluted DNA between SCC and ADC. The levels of MSI and LOH were high in the metaplasia-dysplasia-adenocarcinoma sequence of diluted DNA. The more the diluted DNA was, the higher the rates of MSI and LOH were at the above 7 loci, especially at D3S1616, D5S346, D2S123, D3S1300 and D18S58 loci.

CONCLUSION: The sequence of metaplasia-dysplasia-adenocarcinoma is associated with microsatellite alterations, including MSI and LOH. The MSI and LOH may be the early genetic events during esophageal carcinogenesis, and genetic alterations at the D3S1616, D5S346 and D3S123 loci may play a role in the progress of microsatellite alterations.

Cancer and forensic microsatellites

Although not directly related, circumstances do occur in forensic investigations whereby cancer studies and forensic science cross paths. This review takes a look at the circumstances under which this may occur, and investigates some potential problems that can arise when tumor tissue is submitted for DNA profile analysis. A background to the underlying molecular biology of tumors is described, highlighting the genetic instabilities that are observed in DNA sequences of similar or identical primary structure to the short tandem repeat markers used in forensic DNA profiling kits.

Accumulation of promoter methylation suggests epigenetic progression in squamous cell carcinoma of the esophagus

PURPOSE

Squamous esophageal cancer is common in non-Western countries and has a well-defined progression of preinvasive dysplasia leading to invasive squamous cell carcinoma. We examined the changes in promoter region methylation occurring during neoplastic progression.

EXPERIMENTAL DESIGN

The frequency of epigenetic changes in the promoter region of 14 genes epigenetically silenced in other cancers was determined and examined the most frequent changes in dysplastic lesions using methylation-specific PCR. Invasive squamous carcinomas, low to high grade dysplasia, and normal esophagus were then examined for methylation changes in the promoter region of each of the eight most commonly methylated genes.

RESULTS

Methylation was most frequent for CDKN2A/p16INK4a (52%) but was also common for O(6)-methylguanine-DNA methyltransferase, E-cadherin (CDH1), and retinoic acid receptor beta2. Methylation at individual genes increased in frequency from normal to invasive cancer. Methylation of MLH1 was associated with microsatellite instability in most cases. The number of genes methylated in individual lesions increased as cellular atypia increased. In individual patients, cancers adjacent to dysplasia had the same epigenetic alterations as the less advanced lesions but often had additional methylation of other genes.

CONCLUSIONS

These findings suggest that epigenetic progression parallels the histologic changes observed in the progression of squamous carcinoma of the esophagus.

Frequent microsatellite instability in primary esophageal carcinoma associated with extraesophageal primary carcinoma

Patients with esophageal squamous cell carcinoma (ESCC) frequently develop other primary cancers, such as gastric cancer and head and neck cancer. Details of carcinogenesis in patients with multiple primaries that include esophageal carcinoma with other primary carcinoma (ECOPC) remain uncertain. We examined microsatellite instability (MSI) status, frameshift mutation in target genes of MSI, mismatch repair protein expression and hypermethylation of the hMLH1 promoter region in ECOPC patients to better understand the underlying carcinogenic processes. High frequency MSI (MSI-H) was found in 15 (44.1%) of 34 patients with ECOPC, but in only 6 (14.3%) of 42 patients with esophageal cancer alone (p < 0.01). Frameshift mutations in TGFbetaRII, BAX, MSH3 and MSH6 genes respectively were present in 4, 1, 2 and 2 of 34 ECOPC patients. Immunohistochemical study showed that 12 (80.0%) of 15 MSI-H tumors showed loss of expression of either hMLH1 or hMSH2. In addition, 6 of 9 tumors (66.7%) that showed reduced hMLH1 expression also had hypermethylation of the hMLH1 promoter region. Our findings suggested that carcinogenesis in ECOPC was closely associated with the MSI pathway because of mismatch repair protein deficiency.

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

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.

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

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.

On the nature of genetic changes required for the development of esophageal cancer

It is clear that genetic mutations are necessary for the development of cancer, but the exact number required is not clear, with estimates ranging from one critical hit (e.g., p53) to dozens or perhaps even hundreds of expression changes (by microarray analysis) or chromosomal aberrations. We have used a mathematical model to estimate the critical number of mutations required for the development of esophageal cancer (EC) and to test for the likelihood of an EC major susceptibility gene. Our results suggest that six or seven mutations are required for the development of EC and that there is no evidence of a major susceptibility gene. This does not exclude the possibility that gene-environment interactions may not confer susceptibility or risk. The gradual accumulation of aberrant gene function also can explain the progression of pathologic states seen in the esophagus, from early dysplasia through mild to severe dysplasia and, finally, to cancer, as illustrated in our model.