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Vitamin D - Coggle Diagram

- - - - these studies, and the meta analyses that combine them, are unable to explore the vitamin D–colorectal cancer relationship on the same absolute scale
    - - study size, duration and timing of supplementation, and compliance may have contributed to the null findings (5,7).
      - the RCTs could not evaluate a wide range of vitamin D exposures.
  - - - the Women’s Health Initiative (WHI), 400 IU vitamin D and 1000 mg calcium/d did not lower colorectal cancer risk in postmenopausal women (5).
        
        low dose, limited adherence, and absence of pre- and post intervention 25(OH)D data for all participants complicate interpretation of results (7).
- - - - The biological effects of vitamin D3 are mediated by the vitamin D receptor (VDR) which belongs to the superfamily of nuclear hormone receptors and is expressed in various organs and tissues of the human body, including the kidney and bone cells as well as the colonic mucosa.
        
        n the intestine, VDR plays an important role in regulating cell proliferation, differentiation, and the induction of apoptosis.
        
        Many cell types, including colorectal epithelial cells, contain vitamin D receptors (VDR). These cells are able to convert the circulating 25(OH)D into active 1,25(OH)D metabolites, which in turn bind to the cells’ own VDR to produce an autocrine effect by inducing cell differentiation and by inhibiting proliferation, invasiveness, angiogenesis, and metastatic potential (Figure 1)[117]
  - - - They reported an inverse association between geographical latitude (solar radiation), vitamin D status and CRC incidence and mortality in United States[116].
  - - - One of the largest observational nested case-control study (520000 participants) concluded that there is a strong inverse association between 25(OH)D concentration and CRC[118]
- - - - vitamin D slowed the growth of colorectal cancer in patients with started chemotherapy. [23]
      - vitamin D improves treatment of many types of cancer, by potentiating the anti-tumoral activity of chemotherapeutic agents and enhancing the cytotoxic effect of ionizing irradiation [22]
  - - - positively associated with methylation of genomic long interspersed nuclear element-1 (LINE1) in human rectal mucosa [20]
    - - circulating 25-OH vitamin D was negatively associated with adenomatous polyposis coli (APC) promoter methylation [20]
      - vitamin D intake was correlated with decreased promoter methylation of dickkopf1 (DKK1) and Wnt5A (both considered Wnt antagonists) in CRC tumors [21]
- - - - did not result in significant improvement in relapse-free survival at 5 years
- - - - 1.25(OH)2 The treatment of the LoVo and HT29 cell lines with D3, calcipotriol or 20(OH)D3 in Matrigel caused a statistically significant inhibition of colony size at a concentration of only 20 nM, with stronger inhibition at 500 nM
    - - moderately differentiated cells (LoVo and HT29 cell lines) are more sensitive to vitamin D analogs compared with poorly differentiated HCT116 cells.
        
        this correlation does not hold for the MTT assay results