Plasma Levels of Homocysteine and the Occurrence and Progression of Rectal Cancer

Hyperhomocysteinemia and Disease-Is 10 μmol/L a Suitable New Threshold Limit?

Hyperhomocysteinemia (HHcy) is a medical condition characterized by an abnormally high level of homocysteine (Hcy) in the blood. Homocysteine is a toxic sulfur-containing amino acid that is produced during the metabolism of methionine. Under normal circumstances, Hcy is recycled back to methionine via the remethylation pathway, through the action of various enzymes and vitamins, particularly folic acid (vitamin B9) and B12 used when intracellular methionine levels are low, thus restoring the necessary levels to correctly maintain active protein synthesis. A second pathway, used in cases of intracellular methionine excess, (the trans-sulfuration pathway) is the one that recycles Hcy into cysteine (a precursor of glutathione), first passing through cystathionine (via the enzyme cystathionine beta-synthase), a reaction that requires vitamin B6 in its active form. HHcy has been identified as a risk factor for a variety of disorders, including cardiovascular diseases, multiple sclerosis, diabetes, Alzheimer's and Parkinson's diseases, osteoporosis and cancer. However, it remains unclear whether the slightly elevated concentration of Hcy (Hcy 7-10 μmol/L) is a causative factor or simply a marker of these pathologies. In human plasma, the concentration of Hcy ([Hcy]) is classified as mild (15 to 30 μmol/L), moderate (30 to 100 μmol/L), and severe (greater than 100 μmol/L). Interestingly, many laboratories continue to consider 25 μmol/L as normal. This review seeks to examine the controversial literature regarding the normal range of HHcy and emphasizes that even a [Hcy] level of 10 μmol/L may contribute to the development of several diseases, aiming to discuss whether it would be appropriate to lower the threshold of HHcy normal values.

Elevated serum homocysteine levels associated with poor recurrence-free and overall survival in patients with colorectal cancer

This study aimed to evaluate the significance of homocysteine (HCY) levels in predicting recurrence-free survival (RFS) and overall survival (OS) in colorectal cancer (CRC) patients. This retrospective study involved 1272 CRC patients. The risk of mortality increased with increasing HCY levels in CRC patients. The optimal HCY cutoff value in CRC patients was 15.2 μmol/L. The RFS (45.8% vs. 60.5%, p < 0.001) and OS (48.2% vs. 63.2%, p < 0.001) of patients with high HCY levels were significantly lower than those of patients with low HCY levels. Patients with high HCY levels were older, male, had large tumours, high carcinoembryonic antigen (CEA) levels, and long hospital stays, and incurred high hospitalisation costs. Multivariate analysis showed that when HCY levels exceeded 15.2 μmol/L, the risk of adverse RFS and OS increased by 55.7% and 61.4%, respectively. Subgroup analysis showed that HCY levels could supplement CEA levels and pathological staging. We constructed HCY-based prognostic nomograms, which demonstrated feasible discrimination and calibration values better than the traditional tumour, node, metastasis staging system for predicting RFS and OS. Elevated serum HCY levels were strongly associated with poor RFS and OS in CRC patients. HCY-based prognostic models are effective tools for a comprehensive evaluation of prognosis.

Assessment of biochemical factors in blood serum of patients with oral squamous cell carcinoma

Background

Recently, the role of biochemical factors in the etiology of oral squamous cell carcinoma (OSCC) has attracted some attention. Serum levels of biochemical factors may change in cancer patients. This study aimed to assess the serum level of folate, Vitamin B12, homocysteine, iron, copper, and selenium in patients with OSCC.

Materials and Methods

This descriptive analytical study was conducted on 30 primary OSCC patients (15 males and 15 females) presenting to Imam Khomeini Cancer Institute, who had not yet undergone treatment. Blood samples were taken and serum levels of folate, Vitamin B12, homocysteine, iron, copper, and selenium were measured. Serum levels of micronutrients in patients with different tumor sizes were analyzed by one-way ANOVA. Serum levels of micronutrients were compared among groups with and without metastasis and lymph node involvement using Student's t-test (P < 0.05).

Results

Serum levels of B12, folic acid, homocysteine, copper, iron, and selenium were 232.5 ± 102.68, 8.66 ± 4.06, 18.87 ± 8.81, 96.0 ± 22.64, 55.27 ± 40.58, and 92.47 ± 18.83 ng/mL, respectively. Relatively similar values were measured in patients with different tumor sizes with and without lymph node involvement and presence or absence distant metastasis. However, the serum level of folic acid in OSCC patients without lymph node involvement was significantly higher than that in OSCC patients with lymph node involvement (P < 0.05).

Conclusion

Despite some variations, serum levels of micronutrients in OSCC patients were within the normal limits. Considering the variations in serum level of copper in OSCC patients, it may be used as a diagnostic marker. However, further studies are warranted in this respect.

Longitudinal Analysis of 1α,25-dihidroxyvitamin D3 and Homocysteine Changes in Colorectal Cancer

BACKGROUND

1α,25-dihydroxycholecalciferol (1,25(OH)2D3) and homocysteine are known to play a role in the pathophysiology of colorectal cancer (CRC). In health, the two changes are inversely proportional to each other, but little is known about their combined effect in CRC.

METHODS

The serum 1,25(OH)2D3 and the homocysteine levels of eighty-six CRC patients were measured, who were enrolled into four cohorts based on the presence of metastases (Adj vs. Met) and vitamin D3 supplementation (ND vs. D).

RESULTS

1,25(OH)2D3 was constant (Adj-ND), increased significantly (Adj-D, p = 0.0261), decreased (Met-ND), or returned close to the baseline after an initial increase (Met-D). The longitudinal increase in 1,25(OH)2D3 (HR: 0.9130, p = 0.0111) positively affected the overall survival in non-metastatic CRC, however, this effect was cancelled out in those with metastasis (p = 0.0107). The increase in homocysteine negatively affected both the overall (HR: 1.0940, p = 0.0067) and the progression-free survival (HR: 1.0845, p = 0.0073). Lower 1,25(OH)2D3 and/or higher homocysteine level was characteristic for patients with higher serum lipids, albumin, total protein, white blood cell and platelet count, male sex, and right-sided tumors. No statistically justifiable connection was found between the target variables.

CONCLUSIONS

A measurement-based titration of vitamin D3 supplementation and better management of comorbidities are recommended for CRC.

Kobalamina – właściwości biomedyczne i niedobór w ujęciu biochemicznym

Kobalamina (witamina B12) jest rozpuszczalnym w wodzie związkiem organicznym, zaliczanym do witamin grupy B. Złożona budowa i polarność cząsteczki witaminy B12 sprawiają, że do jej prawidłowego wykorzystania i przemian w organizmie człowieka niezbędny jest udział wyspecjalizowanych białek. Głównym źródłem kobalaminy człowieka jest pokarm pochodzenia zwierzęcego. Ze względu na rezerwy tkankowe tej witaminy, jej niedobór ujawnia się dopiero po kilku latach niewystarczającej podaży z pożywieniem. Badania przesiewowe pod kątem deficytu kobalaminy są jednak uzasadnione u osób z czynnikami ryzyka hipokobalaminemii, takimi jak: stan po resekcji żołądka lub jelita cienkiego, dieta wegańska, długotrwałe stosowanie metforminy, antagonistów receptora histaminowego H2 oraz leków z grupy inhibitorów pompy protonowej, a także podeszły wiek.

Witamina B12 jako kofaktor enzymatyczny uczestniczy w licznych przemianach wewnątrzmitochondrialnych oraz w syntezie metioniny, niezbędnej do powstania S-adenozylometioniny istotnej w procesie metylacji cząsteczek biologicznie czynnych. Przez powiązania metaboliczne z kwasem foliowym kobalamina wpływa na proces syntezy DNA i podział komórki. Obecnie coraz częściej zwraca się uwagę na potencjalny udział niedoboru witaminy B12 w patogenezie chorób neurodegeneracyjnych, a także nowotworowych. Niedobór kobalaminy na poziomie molekularnym destabilizuje genom komórek, zwiększając ryzyko ich złośliwej transformacji. Jednak u osób z chorobą nowotworową lub obciążonych ryzykiem jej rozwoju witamina B12 może nasilać ekspansję komórek neoplastycznych.

Homocysteine inhibits pro-insulin receptor cleavage and causes insulin resistance via protein cysteine-homocysteinylation

Elevation in homocysteine (Hcy) level is associated with insulin resistance; however, the causality between them and the underlying mechanism remain elusive. Here, we show that Hcy induces insulin resistance and causes diabetic phenotypes by protein cysteine-homocysteinylation (C-Hcy) of the pro-insulin receptor (pro-IR). Mechanistically, Hcy reacts and modifies cysteine-825 of pro-IR in the endoplasmic reticulum (ER) and abrogates the formation of the original disulfide bond. C-Hcy impairs the interaction between pro-IR and the Furin protease in the Golgi apparatus, thereby hindering the cleavage of pro-IR. In mice, an increase in Hcy level decreases the mature IR level in various tissues, thereby inducing insulin resistance and the type 2 diabetes phenotype. Furthermore, inhibition of C-Hcy in vivo and in vitro by overexpressing protein disulfide isomerase rescues the Hcy-induced phenotypes. In conclusion, C-Hcy in the ER can serve as a potential pharmacological target for developing drugs to prevent insulin resistance and increase insulin sensitivity.

Current state and future direction of screening tool for colorectal cancer

As the second-most-common cause of cancer death, colorectal cancer (CRC) has been recognized as one of the biggest health concerns in advanced countries. The 5-year survival rate for patients with early-stage CRC is significantly better than that for patients with CRC detected at a late stage. The primary target for CRC screening and prevention is advanced neoplasia, which includes both CRC itself, as well as benign but histologically advanced adenomas that are at increased risk for progression to malignancy. Prevention of CRC through detection of advanced adenomas is important. It is, therefore, necessary to develop more efficient detection methods to enable earlier detection and therefore better prognosis. Although a number of CRC diagnostic methods are currently used for early detection, including stool-based tests, traditional colonoscopy, etc., they have not shown optimal results due to several limitations. Hence, development of more reliable screening methods is required in order to detect the disease at an early stage. New screening tools also need to be able to accurately diagnose CRC and advanced adenoma, help guide treatment, and predict the prognosis along with being relatively simple and non-invasive. As part of such efforts, many proposals for the early detection of colorectal neoplasms have been introduced. For example, metabolomics, referring to the scientific study of the metabolism of living organisms, has been shown to be a possible approach for discovering CRC-related biomarkers. In addition, a growing number of high-performance screening methodologies could facilitate biomarker identification. In the present, evidence-based review, the authors summarize the current state as recognized by the recent guideline recommendation from the American Cancer Society, US Preventive Services Task Force and the United States Multi-Society Task Force and discuss future direction of screening tools for colorectal cancer. Further, we highlight the most interesting publications on new screening tools, like molecular biomarkers and metabolomics, and discuss these in detail.

Metabolomics Biomarkers for Detection of Colorectal Neoplasms: A Systematic Review

BACKGROUND

Several approaches have been suggested to be useful in the early detection of colorectal neoplasms. Since metabolites are closely related to the phenotype and are available from different human bio-fluids, metabolomics are candidates for non-invasive early detection of colorectal neoplasms.

OBJECTIVES

We aimed to summarize current knowledge on performance characteristics of metabolomics biomarkers that are potentially applicable in a screening setting for the early detection of colorectal neoplasms.

DESIGN

We conducted a systematic literature search in PubMed and Web of Science and searched for biomarkers for the early detection of colorectal neoplasms in easy-to-collect human bio-fluids. Information on study design and performance characteristics for diagnostic accuracy was extracted.

RESULTS

Finally, we included 41 studies in our analysis investigating biomarkers in different bio-fluids (blood, urine, and feces). Although single metabolites mostly had limited ability to distinguish people with and without colorectal neoplasms, promising results were reported for metabolite panels, especially amino acid panels in blood samples, as well as nucleosides in urine samples in several studies. However, validation of the results is limited.

CONCLUSIONS

Panels of metabolites consisting of amino acids in blood and nucleosides in urinary samples might be useful biomarkers for early detection of advanced colorectal neoplasms. However, to make metabolomic biomarkers clinically applicable, future research in larger studies and external validation of the results is required.