Role of Vitamin D receptor gene in radiation-induced neoplastic transformation of human breast epithelial cell

The CGL1 (HeLa × Normal Skin Fibroblast) Human Hybrid Cell Line: A History of Ionizing Radiation Induced Effects on Neoplastic Transformation and Novel Future Directions in SNOLAB

Cellular transformation assays have been utilized for many years as powerful in vitro methods for examining neoplastic transformation potential/frequency and mechanisms of carcinogenesis for both chemical and radiological carcinogens. These mouse and human cell based assays are labor intensive but do provide quantitative information on the numbers of neoplastically transformed foci produced after carcinogenic exposure and potential molecular mechanisms involved. Several mouse and human cell systems have been generated to undertake these studies, and they vary in experimental length and endpoint assessment. The CGL1 human cell hybrid neoplastic model is a non-tumorigenic pre-neoplastic cell that was derived from the fusion of HeLa cervical cancer cells and a normal human skin fibroblast. It has been utilized for the several decades to study the carcinogenic/neoplastic transformation potential of a variety of ionizing radiation doses, dose rates and radiation types, including UV, X ray, gamma ray, neutrons, protons and alpha particles. It is unique in that the CGL1 assay has a relatively short assay time of 18-21 days, and rather than relying on morphological endpoints to detect neoplastic transformation utilizes a simple staining method that detects the tumorigenic marker alkaline phosphatase on the neoplastically transformed cells cell surface. In addition to being of human origin, the CGL1 assay is able to detect and quantify the carcinogenic potential of very low doses of ionizing radiation (in the mGy range), and utilizes a neoplastic endpoint (re-expression of alkaline phosphatase) that can be detected on both viable and paraformaldehyde fixed cells. In this article, we review the history of the CGL1 neoplastic transformation model system from its initial development through the wide variety of studies examining the effects of all types of ionizing radiation on neoplastic transformation. In addition, we discuss the potential of the CGL1 model system to investigate the effects of near zero background radiation levels available within the radiation biology lab we have established in SNOLAB.

[Vitamin D and breast cancer: is there a link?]

OBJECTIVE

The aim of this review is to know the relationship between breast cancer and vitamin D, synthesised by skin or brought by food or supplementation.

MATERIAL AND METHODS

The selected articles were extracted from the Pubmed database between 1998 and 2012. The keywords used were: "25-hydroxyvitamin D", "breast cancer recurrence", "breast cancer risk", "serum levels of vitamin D", "vitamin D intake". A total of 37 articles were selected.

RESULTS

The sun exposure, via the skin vitamin D synthesis, is associated with a decreased risk of breast cancer. This decrease seems also likely for food contributions and an over 400IU per day vitamin D supplementation. An inverse relationship between plasma 25-hydroxyvitamin D (25-OH-D) level and breast cancer risk has been suggested. An increased 25-OH-D level seems associated with a decreased risk of breast cancer recurrence.

CONCLUSION

Recommendations concerning a vitamin D supplementation could be established, but should be supported by additional studies.

Breast cancer survivors and vitamin D: a review

Recent evidence has suggested a role for vitamin D in breast cancer prevention and survival. Studies have reported an inverse relation between vitamin D intake and the risk of breast cancer, improvements in survival after a diagnosis of breast cancer in women with higher levels of vitamin D, and vitamin D insufficiency in up to 75% of women with breast cancer. Preclinical data have indicated that vitamin D affects up to 200 genes that influence cellular proliferation, apoptosis, angiogenesis, terminal differentiation of normal and cancer cells, and macrophage function. Vitamin D receptors have been found in up to 80% of breast cancers, and vitamin D receptor polymorphisms have been associated with differences in survival. Although ongoing studies have investigated a possible link between adequate levels of vitamin D and improved cancer prognosis, breast cancer survivors may derive additional, non-cancer-related benefits from adequate vitamin D levels, including improvements in bone mineral density, quality of life, and mood. Maintaining adequate vitamin D stores is recommended for breast cancer survivors throughout their lifetime.

Inhibition of Neoplastic Transformation of Benzo[α]pyrene-Treated BALB/c 3T3 Murine Cells by a Phytochemical Extract of Passionfruit Juice

The phytochemical composition of passionfruit juice (PFJ) was hypothesized to have valuable anti-cancer activity, and this was tested in a BALB/c 3T3 neoplastic transformation model. A higher concentration of PFJ compared with a lower concentration was effective in reducing the number, size, and invasiveness of transformed foci. When incubated with another mammalian cell line, the MOLT-4, PFJ was unable to alter the cell cycle kinetics while at the same time was successful in inducing the activity of caspase-3, an enzyme that commits the cell to apoptosis. This suggests that phytochemicals found in PFJ were able to produce the changes in transformed foci due to apoptotic mechanisms rather than by a reduction in cell proliferation. These beneficial results were achieved at levels that could theoretically be attained in the plasma after consumption of the juice.