Tehran University Medical Journal

Background: Evaluation of cell viability is momentous in pharmacologic and oncological research. Cell viability evaluation determines cell sensitivity and consequently treatment outcome. Various methods are available to determine cell survival. Each of these methods evaluates different endpoints. Accordingly, determining the correlation between these methods is important. In this study, in order to determine the viability of human anaplastic thyroid cancer cell line, the sensitivity of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, trypan blue test and clonogenic assay were compared.
Methods: This experimental study was performed in the Cellular and Molecular Research Center at Guilan University of Medical Sciences, Rasht, Iran from October 2016 to March 2017. The human anaplastic thyroid cancer cell line was cultured in Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum (FBS). The cultured cells were treated with melatonin, for 24 hours. Then, the viability of the cells was evaluated by MTT assay, trypan blue test and clonogenic assay. Furthermore, plating efficiency and surviving fraction were used in order to draw survival curve in the clonogenic assay.
Results: The concentration of melatonin at IC50 point was 4.794±0.117 millimolar (mM) in MTT assay, 4.375±0.894 mM in trypan blue test and 2.246±0.326 mM in clonogenic assay. Comparing the IC50 values of these test revealed that C50 values obtained from MTT assay and trypan blue test had no significant difference (P=0.6446), while there was a significant difference between IC50 values obtained from MTT and clonogenic assays (P=0.0032). Moreover, the IC50 values obtained from trypan blue test and clonogenic assay were also significantly different (P=0.0078). The results of the regression analysis of cell viability were shown a linear, positive and significant correlation between these three methods and MTT assay and trypan blue test showed higher correlation (r=0.99, P<0.001).
Conclusion: Based on our results, all these methods were effective to identify cytotoxicity in human anaplastic thyroid cancer cell line, while MTT assay and trypan blue test were more sensitive than clonogenic assay.

Background: Colorectal cancer is the second most common cancer in the world which is mainly caused by epigenetic and environmental factors. Among these epigenetic factors, gut microbiota is an important one. Although it has not been proved a unique group of bacteria correlated with colorectal cancer, these findings have generally demonstrated differences between healthy and disease gut microbiome in population. Actually, the identification and investigation of intestinal microbiota in early detection of colorectal cancer have been highlighted in new researches and studies. Herein, in the current study, we aimed to evaluate the number of selected gut bacteria including Lactobacillus and Escherichia coli and Prevotella in the fecal specimens of adenomatous polyposis patients, colorectal cancerous cases in compared to normal participants in terms of estimating important role of gut microbiota during colorectal cancer initiation and progression.
Methods: The current research was a case-control study. Fecal samples were provided from 31 healthy individuals, 42 adenomatous polyposis patients and 20 colorectal cancer cases that were referred to Taleghani Hospital, Tehran, Iran, from August 2016 to August 2017 for colorectal cancer screening tests. Fecal samples were collected to analyze intestinal bacteria including, Lactobacillus, Escherichia coli, and Prevotella by absolute quantitative real-time polymerase chain reaction (PCR). The number of these gut bacteria was precisely determined by this method of real-time PCR.
Results: Higher number of Prevotella with 24.6 CT number (P<0.005) and E.coli with 20.4 CT number (P<0.015) were achieved in colorectal cancer cases and adenomatous polyposis patients in contrast to samples from normal individuals. On the contrary, the opposite range was observed for the quantification of Lactobacillus and greater numbers of bacteria (CT=28.6) were detected in normal, compared to the colorectal cancer cases and adenomatous polyposis (P<0.001).
Conclusion: The gut microbiota composition of individuals with colorectal cancer and adenomatous polyposis differs from that of healthy individuals, and the higher numbers of pathogenic microbiota versus beneficial microbiota present in those with colorectal cancer and adenomatous polyposis. In contrast, healthy individuals have higher numbers of beneficial gut microbiota than pathogenic microbes. These findings need more experimental analysis and investigation to better clarify.