Potential new cancer biomarkers revealed by quantum chemistry associated with bioinformatics in the study of selectin polymorphisms

Understanding the complex mechanisms involved in diseases caused by or related to important genetic variants has led to the development of clinically useful biomarkers. However, the increasing number of described variants makes it difficult to identify variants worthy of investigation, and poses challenges to their validation. We combined publicly available datasets and open source robust bioinformatics tools with molecular quantum chemistry methods to investigate the involvement of selectins, important molecules in the cell adhesion process that play a fundamental role in the cancer metastasis process. We applied this strategy to investigate single nucleotide variants (SNPs) in the intronic and UTR regions and missense SNPs with amino acid changes in the SELL, SELP, SELE, and SELPLG genes. We then focused on thyroid cancer, seeking these SNPs potential to identify biomarkers for susceptibility, diagnosis, prognosis, and therapeutic targets. We demonstrated that SELL gene polymorphisms rs2229569, rs1131498, rs4987360, rs4987301 and rs2205849; SELE gene polymorphisms rs1534904 and rs5368; rs3917777, rs2205894 and rs2205893 of SELP gene; and rs7138370, rs7300972 and rs2228315 variants of SELPLG gene may produce important alterations in the DNA structure and consequent changes in the morphology and function of the corresponding proteins. In conclusion, we developed a strategy that may save valuable time and resources in future investigations, as we were able to provide a solid foundation for the selection of selectin gene variants that may become important biomarkers and deserve further investigation in cancer patients. Large-scale clinical studies in different ethnic populations and laboratory experiments are needed to validate our results.

NR3C1 rs6198 Variant May Be Involved in the Relationship of Graves' Disease with Stressful Events

Although stressful events are known to trigger Graves' disease (GD), the mechanisms involved in this process are not well understood. The NR3C1 gene, encoding for the glucocorticoid receptor (GR), presents single nucleotide polymorphisms (SNPs) that are associated with stress-related diseases. To investigate the relationship between NR3C1 SNPs, GD susceptibility, and clinical features, we studied 792 individuals, including 384 patients, among which 209 presented with Graves' orbitopathy (GO), and 408 paired healthy controls. Stressful life events were evaluated in a subset of 59 patients and 66 controls using the IES-R self-report questionnaire. SNPs rs104893913, rs104893909, and rs104893911 appeared at low frequencies and presented similar profiles in patients and controls. However, variant forms of rs6198 were rarer in GD patients, suggesting a protective effect. Stressful events were more common in patients than controls, and were reported to have clearly occurred immediately before the onset of GD symptoms in 23 cases. However, no association was found between these events and rs6198 genotypes or GD/GO characteristics. We suggest that the NR3C1 rs6198 polymorphism may be an important protective factor against GD, but its relationship with stressful events needs further investigation.

ODP272 ROUNDUP IS AN IMPORTANT DISRUPTOR THAT CAUSES PROLIFERATIVE EFFECTS ON NORMAL AND ON CANCER THYROID CELLS

Glyphosate has long be suspected to promote endocrine disruptive and even carcinogenic effects, but little is known about its effect at different concentrations on normal and on cancer thyroid cells. Since the endocrine system responds to low chemical concentrations and abnormal cells may have different sensitivity, it is essential to determine the effects of this compound at different levels, including the Acceptable Occupational Exposure Level (AOEL) and the Acceptable Daily Intake (IDA) doses. We used two human thyroid-derived cell lines strains, Nthy-ori 3-1 (from thyroid normal follicular cells) and TPC-1 (from papillary carcinoma) to test 15 different concentrations of Roundup® Original DI, ranging from 6.5 µg/L to 6.500 µg/L, including AOEL and IDA according to the Technical Note Process No. 25351. 056754/2013-17 of the National Health Surveillance Agency (ANVISA) in Brazil. Trypan blue assay and Cell Counting Kit – 8 (CCK-8) were employed to evaluate cell viability and cytotoxicity. Exposures were made for 24 and 48 hours in technical and biological triplicates. We observed a decrease in the number of viable cells at the 24h exposure compared to 48h in both strains. Exposure of Nthy-ori 3-1 and TPC-1 cells for 24h at the AOEL concentration (160µg/L) caused death of 52% and 58% of the cells, respectively, whereas IDA (830µg/L) resulted in 43% e 58% cell death. These data evidence an important disruptive effect of Roundup Original DI® at the acceptable concentrations. After 48h of exposure, AOEL and IDA concentrations caused a lower number of Nthy-ori 3-1 (19% e 15%) and TPC-1 (29% e 23%) dead cells, respectively, suggesting both thyroid strains have compensatory mechanisms that protect them from longer exposures to the herbicide. The CCK-8 assay, on the contrary, showed a proliferative effect on small concentrations: 6.5 µg/L increased the number of viable Nthy-ori 3-1 and TPC-1 cells to 113% and 118%, respectively, at 24h, and this stimulatory effect persisted after 48h of exposure. In contrast, AOEL and IDA concentrations produced a reduction in the number of both strains cells, likewise observed with the Trypan blue assay. Our data demonstrate that thyroid cells exposed to Roundup Original DI® present a non-monotone dose-response curve, which is a well-known characteristic of an endocrine disruptor. The proliferative effect produced on thyroid cells, especially TPC-1 mutant cells, by very low concentrations of this glyphosate-based herbicide widely used around the world, suggests that it may play a role in the increasing incidence rate of thyroid nodules and/or cancer that have been observed worldwide.

Presentation: No date and time listed

ODP276 THYROID CANCER CELLS ARE MORE RESISTANT THAN NORMAL CELLS TO BISPHENOL-A CYTOTOXIC EFFECT

Bisphenol-A (BPA) is a well-known endocrine disruptor that produces important effects on thyroid metabolism, can interfere with TSH transcriptional activity, alter the transcription of T3-associated genes and, thus, modulate its activity in different cell lines. However, its direct effects on thyroid cells, especially on mutated thyroid cells, are still poorly understood. We tested 14 different concentrations of BPA, ranging from 0.4µg/mL to 400µg/mL, including LME (Specific Migration Limit =1μg/mL, recommended as acceptable by the Brazilian National Health Surveillance Agency-ANVISA) on two human thyroid cell lines: Nthy-ori 3-1 (from normal thyroid follicular cells) and TPC-1 (from papillary carcinoma). Cell viability analysis was made using the Trypan blue assay on cells exposed to BPA for 24h and 48h in technical and biological triplicate. We observed a non-monotone dose-response curve, characteristic of disruptors’ effect, on both cell lines, with greater cytotoxic effect with higher doses. In fact,100μg/mL already killed almost all Nthy-ori 3-1 cells (99% at 24h and 97% at 48h), whereasthe doses of 0.78µg/mL; 4µg/mL and 12.5µg/mL caused 50% kill. Optical microscopy revealed some irregular cells lost on the plate, and few debris with50μg/mL. Concentrations of 100 to 400µg/mL produced many dark small cells detached from the plate and clumps of dead cells. The SCI dose (1µg/mL - allowed in daily life), resulted in 79% of Nthy-ori 3-1 cell death after 24h of exposure. However, only 7% of the cell were dead after 48h of exposure to the SCI dose. This reduction in death rate after longer exposure to BPA was observed at all concentrations, suggesting a potent cellular recovery mechanism. The TPC-1 strain showed a different behavior, with a much more linear dose-dependent cytotoxic effect and much more resistance to the harmful effects of BPA at low doses. In fact, 0.4μg/mL to 3.125μg/mL produced less than 10% cell death, and microscopy confirmed the maintenance of the integrity of virtually all cells. On the contrary, BPA concentrations from 100 to 400µg/mL killed almost all TPC-1 cells at both 24h and 48h times. We conclude that this thyroid papillary carcinoma cell line is more resistant than the normal thyroid lineage to low BPA concentrations (from 0.4 to 50µg/mL) but this endocrine disruptor is highly cytotoxic at higher concentrations, causing more than 90% cell deaths on both normal and mutated thyroid cell lines.

Presentation: No date and time listed

Alternation between toxic and proliferative effects of Roundup® on human thyroid cells at different concentrations

Endocrine-disrupting and carcinogenic effects of glyphosate have long been suspected, but little is known about the effect of compounds used in real life at different concentrations, neither in normal nor in thyroid tumor cells. As cancer cells may have different sensitivities and the effect of the product containing glyphosate may be different from that produced by the active ingredient alone, including the Acceptable Occupational Exposure Level (AOEL=160µg/L) and the Acceptable Daily Intake (ADI=830µg/L) determined by ANVISA, we used two human thyroid-derived cell lines, Nthy-ori 3-1 (from normal follicular cells) and TPC-1 (from papillary carcinoma), to test 15 different concentrations of Roundup® Original DI. Trypan blue (TB), CCK-8 and BrdU assays were used to evaluate cytotoxicity, metabolic activity and proliferation with 24h and 48h exposures in technical and biological triplicates. TB showed an important toxic effect, especially after 24h of exposure, in both cell lines. The AOEL concentration caused the death of 43% and 50% of the Nthy-ori and TPC-1 cells, respectively, in 24 h, while ADI resulted in 35% and 58% of cell death. After 48h of exposure, AOEL and ADI caused a lower number of dead Nthy-ori (33% and 18%) and TPC-1 (33% and 37%) cells, respectively, suggesting that the toxic effect of the product disappears and/or both strains have repair mechanisms that protect them from longer exposures. On the other hand, the CCK-8 assay showed that small concentrations of Roundup have a proliferative effect: 6.5µg/L increased the number of both Nthy-ori and TPC-1 cells at 24h, and the BrdU assay confirmed the stimulatory effect with a 321% increase in the absorbance of Nthy-ori cells at 48h. The herbicide produced even more frequent increases in the BrdU absorbance of TPC-1 cells, mainly at 24h. We conclude that thyroid cells exposed to Roundup present a nonmonotonic dual dose-response curve. Low concentrations of the pesticide, considered acceptable, cause significant cell death but also have an important proliferative effect, especially on TPC-1 cells. This herbicide, widely used around the world, may play a role in the increased incidence rate of thyroid nodules and cancer that has been observed in recent decades.