The effect of iodine on cell proliferation in the MCF-7 cell line as a breast cancer model

Introduction and Purpose: Breast cancer is the first cancer type in women today in terms of frequency and mortality rates. Although surgery, radiotherapy, chemotherapy and smart drug treatments are used, alternative treatmentsare still needed. Increasing cases have increased the use of nutritional supplements, vitamins, trace elements and some herbal products thought to be protective. Iodine products are some of them. The link between iodine use and breast cancer incidence was first recognized in epidemiological studies and subsequently supported by animal and cell studies. In our study, we aimed to determine the effect of iodine treatments on the proliferation behaviour of the MCF-7 breast cancer cell line and to simulate the effect of iodine products taken for homoeopathic purposes on an unknown tumour in vitro. Materials and Methods: Proliferation behavior was qualitatively examined by MTT, colony formation, 3D spheroid culture and migration experiments in MCF-7 cells with varying doses (1, 2 and 3 mM) of molecular iodine (I2) and I2+KI. Positivity rates of Ki-67 molecule, a cell proliferation marker, were evaluated with immunofluorescent staining. Results: According to the MTT experiment results, there was no significant decrease in the number of viable cells in both iodine groups at the lowest dose, I2 at a dose of 2 mM caused a 20% decrease in cell viability in 48 hours, and I2+KI increased the number of viable cells by 24 hours. It was determined that it decreased to 85% in an hour and to 74% in 48 hours. At the highest dose, I2 decreased to 61%, I2+KI to 45% in 24 hours, I2 to 31% and I2+KI to 21% in 48 hours. With the migration experiment, intense irregularities at the edges of the drawings in the high-dose iodine groups prevented accurate measurements. Analyzes were excluded from the evaluation. Although cells surviving in 3 mM I2 were observed with the colony formation assay, no colony formation was detected. Colony formation was determined in other groups. It was observed that the cells formed more colonies in I2+KI than in the control group at all three doses. In 3D cultures, a significant increase in spheroid area was observed at 2 mM and 3 mM doses of I2 and only at 3 mM dose of I2+KI compared to the control. A significant change in spheroid density was observed at 2 mM and 3 mM doses of I2 and only at 1 mM dose of I2+KI. Ki-67 scoring showed that Ki-67 positive stained cells were arithmetically close to each other in groups other than 3 mM I2+KI, while 28.5%-8.3% lower positivity was observed in 3 mM I2+KI than other groups. Conclusion: It has been shown that I2 and I2+KI treatments reduce the viability of MCF-7 cells depending on dose and time. Migration experiments were excluded from the evaluation. Iodine applied in different forms showed different effects on colony formation ability. The effect is attributed to the different retention of iodine forms. It has been interpreted that iodine weakens intercellular connections in 3D cultures, and this may lead the cell to apoptosis or undergo epithelial-mesenchymal transformation. Since Ki-67 was evaluated in surviving cells and iodine causes advanced cell loss, it was thought that Ki-67 was not a productive marker in vitro in MCF-7 cells. Key words: MCF-7, breast cancer, iodine, Ki-67, proliferation