Metastasis is a process that involves tumor cell migration from a primary tumor and its invasion to other tissues, which in turn are believed to be driven by a process called epithelial-mesenchymal transition (EMT). EMT process in cancer cells implies increase of malignance and metastatic potential by molecular and phenotypic modifications. MHC class I (MHC-I) is a protein complex used by cells for antigen presentation, specifically to T-cell CD8. It is believed that MHC-I gene expression may fluctuate along different cancer types, biologic processes and molecular modifications which cancer cells may suffer, and it could directly impact on system immunologic responses and T-cell-dependent immunotherapy treatment. This project aimed to evaluate MHC-I and TAP1 gene expression in nonmetastatic origin and metastatic origin cells under the effect of tumor growth factor beta (TGFb), a factor that induces EMT process. Three nonmetastatic cell lineages (A549, H1703, H23) and three metastatic cell lineages (H1792, H2023, H2030) of pulmonary carcinoma were cultured under controlled conditions in RPMI culture media supplemented with 10% of bovine fetal serum (BFS), 1% of antibiotics (penicillin and streptomycin), 2% of glutamine in incubator at 37oC and air atmosphere containing 5% of CO2. Cell cultures were supplemented or not with TGFb (4µg/mL) for 5 days to induce EMT process. After 5 days, cells were evaluated for acquiring mesenchymal cell morphology and MHC-I and TAP1 gene expression (relative quantification). Pool of cells was used to obtain RNA using RNAesy Extraction Kit (QIAGEN®) followed by RT-PCR reaction using High Capacity RNA-to-cDNA Kit (Applied Biosystems®) to obtain cDNA. Relative gene expression was analyzed using Real Time PCR using Fast SYBR™ Green Master Mix (Applied Biosystems®). Except by H23 cell, TGFb incubation showed to be effective and seems to induce EMT process within 5 days culture for both cell types. The cells acquired mesenchymal morphology characteristics such as elongation and increased size. It was also possible to identify a significant gene expression pattern for MHC-I and TAP1 gene expression between control and TGFb groups. Both MHC-I and TAP1 gene expression were shown to be upregulated in the majority of non-metastatic origin cells (A549, H1703, H23; p<0.05) and downregulated in metastatic origin cells (H1792, H2030, H2023; p<0.05). Indeed, nonmetastatic origin cells presented at least twice the expression of MHC-I compared to metastatic origin cells, and TAP1 presented nearly five times more expression in non-metastatic origin cells. Besides the cells apparently undergoing EMT process (morphologic aspects), and MHC-I and TAP1 gene expression differences between cell types, we did not observe such gene expression difference in both cell types when treated with TGFb. Only MHC-I gene expression showed to be affected by the TGFb and presented a slight decrease after 5 days incubation (p<0.05). However, such TGFb effect seems to affect only non-metastatic origin cells. Supposing metastatic origin cells, at some point, have suffered EMT process during metastasis process, it supports that downregulated MHC-I gene expression in metastasis cells could be due to the EMT process. Therefore, we conclude that TGFb was capable of inducing EMT process in both pulmonary carcinoma cell types and affects MHC-I and TAP1 genes expression in nonmetastatic origin cells. We also conclude that MHC-I and TAP1 gene expression are upregulated in nonmetastatic origin cells.

Citation Format: Pedro Ratto Lisboa Pires, Pedro L.P. Xavier, Heidge Fukumasu …