Hepatocellular carcinoma (HCC) is the leading cause of cancer death in men worldwide owing to limited insights into pathogenesis and unsatisfactory efficacy of current therapies. HER2 and TOP2A genes are coamplified in breast and some other cancers. In this study, we investigated gene aberrations of HER2 and TOP2A and protein expressions of HER2, TOP2A, Ki-67, and p53 in tumor and matched nontumor tissues, as well as their associations with clinicopathological features. Gene aberrations were evaluated by FISH and protein expressions by IHC. Neither HER2 overexpression nor HER2 gene amplification was observed in both tumor tissues and matched nontumor tissues. By contrast, TOP2A overexpression was detected in 72.5% of tumor tissues but not detected in matched nontumor tissues. However, TOP2A gene amplification was not observed in both tumor and matched nontumor tissues. TOP2A overexpression was significantly associated with HCC tumor tissues (P < 0.001), hepatitis B surface antigen (HBsAg) in the serum (P = 0.004), and Ki-67 (P = 0.038) but not with age, tumor size, alpha-fetoprotein, TP53, and copy number of TOP2A gene and chromosome 17 centromere. In conclusion, TOP2A overexpression in HCC was not secondary to gene amplification. In addition, neither HER2 amplification nor overexpression could be used as prognostic and predictive marker in HCC.
Background: Epidermal growth factor receptor (EGFR) has emerged as an important therapeutic target. Overexpression of EGFR is frequently observed in hepatocellular carcinoma (HCC) and EGFR activation has been proven to be a potential determinant of primary resistance of HCC cells to sorafenib. In our previous study, we found 13 missense mutations in EGFR exon 19-23 from hepatocellular carcinoma (HCC) tissues, but the functions of these mutations have not been determined. This study aims to determine the kinase activity and sensitivity to erlotinib, a 1st-generation EGFR-tyrosine kinase inhibitor (TKI), of seven HCC-derived mutants (K757E, N808S, R831C, V897A, P937L, T940A, and M947T). Results: Using transduction of pBabe-puro retroviral vector with or without EGFR, we constructed and determined the function of EGFRs in NIH-3T3 cells stably harboring each of the seven mutants, as well as the erlotinib-sensitive L858R-mutant, the erlotinib-resistant T790M-mutant, and EGFR wild type (WT). Our results indicate that the seven mutants are functioning, EGF-dependent, EGFRs. Cells harboring six of the seven mutants could generate some level of EGFR phosphorylation in the absence of EGF, indicating some constitutive kinase activity, but all of the seven mutants remain primarily EGF-dependent. Our results demonstrate that erlotinib induces differential degree of apoptosis and autophagy among cells harboring different EGFRs: complete apoptosis and autophagy (cleavage of both caspase-3 and PARP, and marked LC3-II increment) in L858R-mutant; partial apoptosis and autophagy (only cleavage of caspase-3, and moderate LC3-II increment) in WT and HCC-derived mutants; and no apoptosis and minimal autophagy (no cleavage of caspase-3 and PARP, and minimal LC3-II increment) in T790M-mutant. The seven HCCderived mutants are erlotinib-resistant, as treatment with erlotinib up to high concentration could only induce partial inhibition of EGFR phosphorylation, partial or no inhibition of AKT and ERK phosphorylation, and partial apoptosis and autophagy. Conclusion: The seven HCC-derived EGFR mutants in this study are functioning, EGF-dependent, and erlotinibresistant. Erlotinib induces differential degree of apoptosis and autophagy among cells harboring different EGFRs. The degree of inhibition of EGFR phosphorylation by erlotinib is the determining factor for the degree of apoptosis and autophagy amongst cells harboring EGFR mutants. This study paves the way for further investigation into the sensitivity of these HCC-derived mutants to the 3rd-generation irreversible EGFR-TKI, osimertinib.
Breast cancers with amplification and overexpression of human epithelial growth factor receptor 2 (HER2) are associated with poor prognosis, and targeted for anti-HER2 therapy. Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) are currently the recommended methods to asses HER2 overexpression/amplification. Droplet digital PCR (ddPCR), a highly accurate method to quantify DNA copy number, is potentially a robust alternative for HER2 diagnostics. In the FISH assay and most of previous ddPCR reports, chromosome 17 centromere (CEP17) has been used as the reference control to determine HER2/CEP17 ratio. Nevertheless, miss-classification could occur when HER2 is co-amplified with CEP17. To avoid this inherent defect, in the present study, we employed ddPCR assay using the human eukaryotic translation initiation factor 2C1 (EIF2C1) gene located at chromosome 1p34.3 as the reference control to quantify HER2 copy number in 31 frozen breast cancer tissues. HER2 status of these samples had been determined by FISH and classified as HER2-amplified and HER2-non-amplified breast cancers. The results showed that HER2 determined by ddPCR using HER2/EIF2C1 ratio was in good concordance with HER2 determined by FISH using HER2/CEP17 ratio, the concordance rate 87.1% (27/31), Kappa = 0.719. The sensitivity and specificity of ddPCR assay was 90% (9/10) and 85.7% (18/21), respectively. The median HER2/EIF2C1 copy number ratio in HER2-amplified cancers (6.55, range 1.3–17.3) was significantly higher than in HER2-non-amplified cancers (1.05, range 0.6–3.6, p < 0.001). This study demonstrated that ddPCR using HER2/EIF2C1 ratio could accurately assess HER2 status in frozen breast cancer tissues. Thus, our findings warrant further studies into breast cancer with HER2-equivocal by IHC/FISH.
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