Activity (transcription) of the genes for MLH1, MSH2 and p53 in sporadic colorectal tumours with micro-satellite instability

Immunoexpression of p53 and hMSH2 in oral squamous cell carcinoma and oral dysplastic lesions in Yemen: relationship to oral risk habits and prognostic factors

Although several studies analyzed p53 and mismatch repair (MMR) gene expression separately in oral squamous cell carcinoma (SCC), no reports of combined assessment of both proteins in this cancer. The aim of this study was to investigate the roles of p53 and hMSH2 proteins in oral SCC as well as in oral dysplastic lesions (DL) in Yemen. Immunohistochemistry was used to examine the pattern of expression of p53 and hmsh2 proteins in 70 oral SCC and 21 oral DL obtained from Yemeni patients. p53 Immunoexpression was detected in 24 of the 70 oral SCC (34.3%) and 3 of 21 DL (14.3%) with no significant difference between the two groups. On the other hand, reduced expression of hMSH2 was detected in 26 of the 70 oral SCC (37.1%) and 2 of 21 oral DL (9.5%) with a statistically significant difference (P=0.03). Both proteins were significantly related to the grade of tumor differentiation (P=0.007 and 0.02, respectively). There was an inverse correlation between the levels of p53 and hMSH2 immunoexpression in the oral SCC (r=0.42, P=0.01). This study suggested that p53 may play a role in the early stages of oral carcinogenesis, while hMSH2 may be altered in the late stages. More importantly, the roles of p53 and hMSH2 in oral carcinogenesis seem to be interrelated in the pathogenetic pathway of oral SCC. Such a relationship has not been published previously in this type of cancer and needs to be clarified in future studies.

Appearance of epithelial and stromal genomic instability in background colorectal mucosa of sporadic colorectal cancer patients: relation to age and gender

BACKGROUND

We have previously demonstrated that not only epithelial but also stromal genetic instability possibly contributes to colorectal tumorigenesis. To assess the increasing risk of carcinogenesis in the colorectum with aging, we examined genomic instability in both epithelia and stroma in the background noncancerous mucosa of patients with colorectal carcinomas.

METHODS

In 213 noncancerous colorectal mucosa samples from colorectal cancer cases and 51 normal mucosa specimens of diverticulosis cases, epithelial and stromal genomic instability was analyzed with National Cancer Institute standard microsatellite markers, chromosome 17 (Chr.17) markers and tumor suppressor gene-related markers, using a combination of laser-capture microdissection and GeneScan approaches. Results were compared with immunohistochemically demonstrated expression of FHIT, Rb, WT1, hMLH1 and hMSH2.

RESULTS

Genomic instability (MSI and LOH) in both epithelia and stroma appeared after around 40 years of age and remained relatively constant thereafter at relatively low frequencies (4.8-30.4%). The Epithelial LOH tended to show a stepwise increase in people in their 40s and 50s along with aging, especially in males. Overall frequencies of both epithelial MSI and LOH in left-side colon and LOH in right-side colon were significantly higher in males than in females. Epithelial hMLH1 expression in MSI (-) cases tended to be reduced with aging.

CONCLUSIONS

Genomic instability of both MSI and LOH in noncancerous colonic mucosa, and more particularly epithelial and stromal LOH, appears relatively early in adults, suggesting age-related changes which increase the risk of cancer development, particularly in males.

Invertebrate p53-like mRNA isoforms are differentially expressed in mussel haemic neoplasia

Mussels of the genus Mytilus are widely used in environmental monitoring. They can develop a leukaemia-like disease, haemic neoplasia, which could be induced, in part, by environmental stressors. The molluscan p53 tumor suppressor gene family was previously shown to be involved in haemic neoplasia at the protein level. The purpose of this study was the quantification of molluscan p53-like isoforms at the mRNA level in mussels with haemic neoplasia compared to normal controls. The three isoforms monitored were a p53-like, a TAp63/73-like containing an intact transactivation (TA) domain, and an NH(2)-terminally truncated p63/73 isoform termed DeltaNp63/p73-like that lacks the full TA domain. Using a comprehensive data set of 62 individual Mytilus trossulus and reverse transcription real-time PCR, we found that both the p53 and the DeltaNp63/73 isoforms were up-regulated in neoplastic haemocytes compared to normal haemocytes (p<0.0001). In contrast, the mRNA levels of the non-truncated isoform TAp63/73 did not change significantly in mussels with the disease at alpha=0.01 (p=0.0141), in contrast to previous findings at the protein level. Correlations in mRNA levels between the truncated isoform and the full-length isoforms in normal haemocytes were lost in neoplastic haemocytes. The increase in mRNA concentration of the truncated DeltaNp63/73 isoform in molluscan haemic neoplasia is similar to observations in many human cancers and cell lines and underlines the phylogenetically ancient oncogenic role of this isoform.

Significant increase of colonic mutated crypts correlates with age in sporadic cancer and diverticulosis cases, with higher frequency in the left- than right-side colorectum

Mild periodic acid-Schiff (mPAS) staining can discriminate non-O-acetylated (mPAS-positive) from O-acetylated (mPAS-negative) epithelial sialoglycoproteins in human colonic mucosa, allowing the three haplotypes expressed from a single polymorphic autosomal gene (oat) to be distinguished. In heterozygotes, we previously demonstrated wholly mPAS-positive (stem cell mutated) crypts and clusters of two or more mPAS-positive crypts to be significantly increased with duration of ulcerative colitis. To establish whether such an increase in the number of mutated crypts with age also occurs in normal individuals or in cases with diverticulosis, the O-acetylation phenotype in the non-cancerous colonic mucosa of 47 sporadic colorectal cancer patients who were heterozygotes for oat was tested with mild-PAS staining. PAS-positive crypts were assessed histologically in relation to age and compared between the left (sigmoid colon and rectum) and right (cecum and ascending colon) sides of the colorectum. Wholly mPAS-positive (stem cell mutated) crypts and foci in heterozygotes were found to be increased significantly (P < 0.0001) in the left side with aging (r = 0.598 and 0.643, respectively). Such a positive correlation with aging was also confirmed in 19 diverticulosis cases without cancer (r = 0.797 and 0.793, respectively). The frequency of mutated crypts and foci on the right side was significantly lower than on the left side in both spontaneous colorectal cancer and diverticulosis cases. The results provide support for an intimate relationship between accumulation of mutated crypts with aging, possibly with significance for colorectal cancer development. Furthermore, the environment in the right side of the colon may be different from that in the left side in this regard.

Does Biomolecular Characterization of Stage II/III Colorectal Cancer Have Any Prognostic Value?

As new improvements in the treatment of colorectal cancer have become available, it has become important to understand the benefits of new therapies or the deleterious effects stemming from the increased risk of toxicity. In particular, a more rational approach to adjuvant chemotherapy for patients with stage II/III disease should be defined by understanding which patients have a higher recurrence risk. Many studies have investigated several molecular markers, but none has been definitively associated with patient outcome. We present a review of studies that have evaluated the immunohistochemical correlation between expression of some biomarkers, such as thymidylate synthase, p53, Ki-67, Bcl-2, and microsatellite instability status expressed by Mut-L homologue 1 and Mut-S homologue 2 proteins, and the prognosis of patients with stage II/III colorectal cancer. We have evaluated studies in which > or = 100 patients were involved in an effort to ensure a representative study group. The only biomarker likely to have a prognostic value is microsatellite instability status, which correlated with a better prognosis.

Expression of angiogenic VEGF-A (soluble isoforms 121, 165) and lymphangiogenic VEGF-C in colorectal cancers with micro-satellite instability

BACKGROUND AND OBJECTIVES

Colorectal cancers (CRC) with high-level micro-satellite instability (MSI-H) show reduced metastatic potential and better prognosis compared to stage-matched stable (MSS) cancers. Angiogenesis/lymphangiogenesis, central to tumour growth and spread, is mediated by vascular endothelial growth factor (VEGF) cytokines, but little is known of their relationship to MSI.

METHODS

In this study, 67 sporadic CRC with identified MSI status, and 8 samples of normal colon were analysed for VEGF-A soluble isoforms (VEGF-121/VEGF-165) and VEGF-C gene transcription (by RT-PCR and scanning densitometry), and blood vessel density (BVD; measuring angiogenesis) and VEGF-C protein expression (measuring lymphangiogenesis).

RESULTS

Compared to normal colon, VEGF-165 transcription was reduced (P < 0.05), but VEGF-121 transcription was higher in MSS (P < 0.06) and MSI-L (P < 0.01) cancers (but similar in MSI-H). VEGF-165 transcription was unrelated to MSI, but VEGF-121 transcription was elevated in MSI-L (P < 0.06). There was a weak inverse correlation with VEGF-121 transcription and Dukes stage (P < 0.09), and with BVD and MSI (P < 0.09). With a singular di-nucleotide loci mutation (MSI-L), VEGF-121 (P < 0.03) and VEGF-C (P < 0.04) transcription was elevated.

CONCLUSIONS

MSI-H cancers have reduced angiogenic/lymphangiogenic potential, and transcription of VEGF-121 may be important in early growth and spread of CRC. Elevated VEGF-121 and VEGF-C transcription with singular di-nucleotide mutations may aid in the identification of distinct MSI-L cancers.