Recent novel and promising findings include additional abnormalities in key pathways associated with thyroid tumorigenesis (RET-Ras-BRAF-MEK; RET-beta-cateinin; TRK-PI3K-AKT; and MDM-p53-PTEN), single-nucleotide polymorphisms associated with thyroid cancer susceptibility, epigenetic silencing, alternative splicing, and gene expression abnormalities.
Genetic alterations in pathways, including the mitogen‑activated protein kinase (MAPK)/extracellular signal‑regulated kinase (Erk) and phosphatidylinositol‑3‑kinase (PI3K)/protein kinase B (Akt) pathways, are the driving force behind the development of differentiated thyroid cancer cases into aggressive and undifferentiated forms of thyroid cancer.
We recently showed that autocrine production of interleukin (IL)-4 and IL-10 controls thyroid cancer cell survival, growth, and resistance to chemotherapy through activation of Janus-activated kinase/signal transducers and activators of transcription (JAK/STAT) and phosphatidylinositide 3'-OH kinase (PI3K)/Akt pathways.
We investigated SNP rs17849071 (minor allele G and major allele T) in PIK3CA in thyroid tumors in 503 subjects by PCR and sequencing of a region of intron 9 carrying this SNP.
Our findings suggest that miR-145 is a master regulator of thyroid cancer growth, mediates its effect through the PI3K/Akt pathway, is secreted by the thyroid cancer cells, and may serve as an adjunct biomarker for thyroid cancer diagnosis.
Mechanically, our data demonstrated that tumor-promoting role of N-cadherin in thyroid cancer was closely related to the activities of the MAPK/Erk, the phosphatidylinositol-3-kinase (PI3K)/Akt and p16/Rb signaling pathways in addition to affecting the EMT process.
Long Noncoding RNA LINC003121 Inhibits Proliferation and Invasion of Thyroid Cancer Cells by Suppression of the Phosphatidylinositol-3-Kinase (PI3K)/Akt Signaling Pathway.
Initiation and progression of thyroid cancer involves multiple genetic and epigenetic alterations, of which mutations leading to the activation of the MAPK and PI3K-AKT signaling pathways are crucial.
These data suggest that mutation of the PIK3CA gene is not common, but its amplification is relatively common and may be a novel mechanism in activating the PI3K/Akt pathway in some thyroid tumors.
Demethylating the hypermethylated REC8 gene restored its expression in thyroid cancer cells in which the PI3K pathway was genetically over-activated and induced expression of REC8 protein inhibited the proliferation and colony formation of these cells.
This genotype-based targeting of the PI3K/Akt pathway using Akt and mTOR inhibitors may offer an effective therapeutic strategy for thyroid cancer and warrants further studies.
In conclusion, the data of this study suggested that naringin presented anti-tumor effects in TC cells through inhibiting TC cell proliferation and inducing cell apoptosis via regulating the expression of cell proliferation and apoptosis related genes and PI3K/AKT pathway activation.
Thyroid cancer (TC) is frequently associated with BRAF or RAS oncogenic mutations and RET/PTC rearrangements, with aberrant RAF-MEK-ERK and/or PI3K pathway activation.
These distinct genetic alterations constitutively activate the MAPK, PI3K and β-catenin signaling pathways, which have been implicated in thyroid cancer development and progression.
Treatment of the most resistant cell line, 8505c, using lexatumumab in combination with the BRAF(V600E) inhibitor, PLX4720, and the PI3K inhibitor, LY294002, (triple-drug combination) sensitizes the cells by triggering both the extrinsic and intrinsic apoptotic pathways in vitro as well as 8505c orthotopic thyroid tumors in vivo.
A mutual exclusivity among these genetic alterations was seen in BTA, FTC, and PTC, suggesting an independent role of each of them through the PI3K/Akt pathway in the tumorigenesis of the differentiated thyroid tumors.
Genetic alterations, particularly PIK3CA amplification and mutations and ras mutations, are the major cause of aberrant activation of this pathway in thyroid tumors.