Selenium levels in colorectal cancer: A systematic review and meta-analysis of serum, plasma, and colorectal specimens.

BACKGROUND: Colorectal cancer (CRC) is a growing public health problem. Several clinical studies have shown a potentially protective effect of selenium (Se), but the reports are inconsistent. The objective of the study was to examine the evidence for relation between serum/tissue Se status and CRC. METHOD AND MATERIALS: In this Systematic Review and Meta-Analysis, we searched Cochrane Library, EBSCOhost, EMBASE, ProQuest, PubMed/MEDLINE, Scopus, and Web of Science for studies reporting serum/plasma/whole blood/tissue Se concentrations in CRC patients and controls for articles published till August 2023. Meta-analysis was performed, and study quality, heterogeneity, and small study effects were assessed. Based on a random effects model, summary mean differences in serum levels of Se between CRC patients and healthy controls, and Se levels between malignant and matched non-malignant tissue specimens were assessed. RESULTS: After initial screening, a total of 24 studies (18 serum and 6 tissue studies) with a pooled total of 2640 participants were included in the meta-analysis. CRC patients had significantly lower serum Se levels than healthy controls, being the difference between the two equal to 3.73 µg/dl (95% CI: 6.85-0.61). However, the heterogeneity was very high, I2= 99% (p < 0.01). Our meta-analysis showed higher Se levels in CRC cancerous specimens than in matched healthy colon tissue: the increase was equal to 0.07 µg/g wet tissue weight (95% CI: 0.06-0.09; p= 0.02). CONCLUSIONS: CRC patients have lower serum and higher colon cancerous tissue Se levels. Some factors, such as Se levels in different tumor grades of CRC need to be further considered for a more conclusive association between Se levels and risk of CRC.

Over-Expression of Cyclooxygenase-2 in Colorectal Cancer Patients.

Background: Colorectal carcinoma (CRC) is the most common neoplasm of the gastrointestinal tract. COX-2 plays an important role in CRC development and is a key target for the regression of colorectal tumorigenesis by nonsteroidal anti-inflammatory drugs. The present study was conducted to examine the relationship of the levels of COX-2 in CRC patients with the clinico-pathological parameters and also to assess its usefulness as a potential biomarker for diagnosis of CRC. Methods: Prior to surgery, 30 CRC patients were enrolled and the samples from colon tumors and surrounding tissues were taken after they underwent surgical intervention at PGIMER, Chandigarh. mRNA expression levels of COX-2 were examined in 30 CRC and adjacent normal colonic mucosa by quantitative polymerase chain reaction (qPCR). The expression of COX-2 was assessed by immunohistochemical method using rabbit polyclonal antibodies against human COX-2 protein. Results: The quantitative relative expression of COX-2 mRNA was observed to be significantly higher (p<0.05) in colorectal cancer tissues as compared to adjacent normal colon tissues. Also, female CRC patients showed significantly higher (p<0.009) expression of COX-2 mRNA vis-a-vis male colorectal cancer patients. This is the first study which has reported a direct relationship between COX-2 mRNA expressions in male colorectal cancer patients versus females. Further, immunohistochemistry of COX-2 confirmed the quantitative real time-PCR findings. Conclusion: Our study shows that COX-2 over expression in colorectal carcinoma patients is closely associated with clinico-pathological parameters and is more pronounced in males versus females. Further, COX-2 mRNA expression can serve as a potential biomarker for the diagnosis of CRC.

Increased Nuclear Factor-κB/RelA Expression Levels in Human Colorectal Carcinoma in North Indian Patients.

Colorectal cancer is a major cause of cancer-related death in many countries. Inflammatory pathway is considered to play a major role in colorectal carcinogenesis. Nuclear factor kappa B (NF-κB) pathway is a link between inflammation and cancer. NF-κB is a transcription factor which belongs to the Rel family. Activation of NF-κB has been shown to play a role in cell proliferation, apoptosis, cytokine production, and oncogenesis. The aim of the present study was to evaluate the expression levels of NF-κB/RelA in colorectal carcinoma using Real-time PCR. For this study, tumor tissue was taken from general surgery OT of PGIMER, Chandigarh from twenty-seven patients of colorectal cancer treated by surgery. Adjacent colonic mucosa specimens were also collected from all patients as normal control tissue. Real-time PCR was performed to determine the nuclear factor-κB/RelA expression levels in twenty-seven pairs of colorectal adenocarcinoma and adjacent normal colonic tissues. Out of 27 CRC patients, 18 were males and 9 females. Mean age of patients was 51.1 ± 14.8 years. Most of the cases were males (67%). Seventy percent of the cases were early (I-II) and 30% were advanced (III-IV) tumor stage. The quantitative relative expression of NF-kB mRNA was found to be significantly higher (p < 0.05) in CRC tissues as compared with that in adjacent normal colon tissues. From this study, we can conclude that RelA/NF-kB pathway is expressed constitutively in colorectal adenoma and adenocarcinomas. Thus, RelA/NF-kB might play an important role in colorectal tumorigenesis.