In contrast, activation, or overexpression of GHR increased chemoresistance and metastasis by increasing the expression and promoter activity, of ABCG2.
Phenotypic plasticity arose with differential expression of metastasis and stemness associated genes (LGR5, FZD10, DTX1, ErbB3, FTH1 and DLL4) and pathways (DNA replication and repair, ABC transporter, Hedgehog, Notch and metabolic pathways).
Our results suggest that pharmacological inhibition of ABCB1 and ABCG2 during osimertinib therapy might potentially be considered to further benefit patients with brain (micro-)metastases positioned behind an intact blood-brain barrier, or with substantial expression of these transporters in the tumor cells, without invoking a high toxicity risk.
AhR promotes the cancer stem-like phenotype and drives metastasis by directly targeting the promoters of 'stemness' genes, such as the ATP-binding cassette sub-family G member 2 (ABCG2) gene.
We further revealed that fructose substitution enhanced the metastatic potential of human PDAC cell via selective outgrowth of aggressive ABCG2-positive subpopulations and elevating N-acetylmannosamine levels that upregulated β-galactoside α2,6-sialyltransferase 1 (ST6Gal1), thereby promoting distant metastasis.
Our results suggest that pharmacological inhibition of ABCG2 and ABCB1 during ponatinib therapy might benefit patients with brain (micro)metastases positioned behind an intact blood-brain barrier, or with substantial expression of these transporters in the malignant cells.
Resistant cells expressed higher levels of genes coding for cancer stem cell markers (JARID1B, CD271 and Fibronectin) as well as genes involved in drug resistance (ABCG2), cell invasion and promotion of metastasis (MMP-1 and MMP-2).
The group with metastasis showed higher expression levels of Shh, ABCG2, and Wnt than did the group without metastasis, and patients with strong ABCG2 expression, Wnt, or LRP expression showed higher cumulative incidence of lymph node or distant metastasis, implying that activation of the Shh and Wnt signaling pathway is associated with aggressive behavior of the tumor.
Primary and corresponding metastatic samples were available for 15 patients, and 13 of the metastatic tumors had higher ABCG2 expression than the corresponding primary tumors, but only 1 of these tumors responded to FOLFOX (7.7%).
Whether this adverse prognostic effect results from resistance imparted to the cancer cells as the direct result of BCRP efflux of anticancer drugs, or whether BCRP expression (and also Pgp expression - coexpression of these transporters is common among poor risk cancers) serves as indicators of the activity of signaling pathways that enhance cancer cellular proliferation, metastases, genomic instability, enhance drug resistance, and oppose programmed cell death mechanisms is yet unknown.
We investigated proteins involved in regulation of apoptosis (p53, BAX, BCL-2, and BCL-X(L)), cell cycle control [p21 and retinoblastoma protein (RB)], and drug export and inactivation [P-glycoprotein, multidrug resistance-associated protein (MRP) 1, MRP2, breast cancer resistance protein, lung resistance protein, metallothionein, and glutathione S-transferase pi] immunohistochemically in samples of unselected GCT patients (n = 20), patients with advanced metastatic disease in continuous remission after first-line chemotherapy (n = 12), and chemotherapy-refractory patients (n = 24).