In mainland China, "adenocarcinoma" and "non-smoker" are independent predictors for EGFR mutations. Response to gefitinib favors patients with EGFR mutations. The clinical selected populations for gefitinib are non-smokers with adenocarcinoma.

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Purpose: Studies have shown that mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase domain are associated with response of lung cancer to gefitinib (Iressa, AstraZeneca Corp., Shanghai, China). A higher incidence of EGFR mutation was observed in non^small cell lung cancer (NSCLC) patients of Japanese origin compared with those of American origin. However, no data about such mutations in Chinese patients with NSCLC could be obtained. Methods: Primary NSCLC tissues were obtained for analysis of mutations in exons 18 to 21 of EGFR from a total of 76 patients, of whom 54 did not receive gefitinib therapy and 22 did. PCR products were sequenced directly and mutations were confirmed by an independent PCR and sequence analysis. All types of mutation were cloned and sequenced. Results: A total of 10 types of mutation were found in the series of patients, including two different silent mutations in exon 20 from 11patients. More than half of the silent mutations (6 of 11) in exon 20 coexisted with other mutations. Mutations were more frequent in adenocarcinoma (17 of 35; 48.6%) compared with squamous carcinoma (1 of 19; 5.3%) among untreated patients. Similar mutations were observed in all seven gefitinib-treated patients with partial response, and no mutations were detected in all eight patients with progressive disease (P < 0.001), except two silent mutations. Three mutations were observed in seven patients with stable disease. Conclusions: Mutations in the epidermal growth factor receptor tyrosine kinase domain in lung adenocarcinomas from Chinese patients were more frequent than reported previously in lung adenocarcinomas from American patients. Such mutations were well correlated with tumor response to gefitinib.

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BackgroundSelective estrogen receptor modulators, such as tamoxifen, play a pivotal role in the treatment of luminal-type breast cancer. However, in clinical applications, nearly half of breast cancer patients are insensitive to tamoxifen, a small number of whom have early recurrence or disease progression when receiving tamoxifen. The underlying mechanism of this resistance has not been determined. ZNF703 is a novel oncogene in the 15% of breast cancers that harbor 8p12 amplifications. Therefore, the goal of our study was to explore the role of ZNF703 in tamoxifen resistance.Methodology/Principal FindingsWe used immunohistochemistry techniques to examine ZNF703 expression in stage I-III primary breast cancer specimens and found a positive expression rate of 91.3%. All patients were divided into either high or low ZNF703 expression groups. We found that high ZNF703 expression mainly occurred in ER+ and PR+ breast cancers. Furthermore, 4-hydroxytamoxifen had different modes of action in breast cancer cell lines with high or low ZNF703 expression. ZNF703 overexpression in MCF-7 breast cancer cells activated the Akt/mTOR signaling pathway, downregulated ERα, and reduced the antitumor effect of tamoxifen. Low-dose tamoxifen did not suppress, but rather, stimulated the growth of cells overexpressing ZNF703. ZNF703 knockdown in MDA-MB-134 and HCC1500 luminal B-type breast cancer cell lines by siRNA significantly decreased survival rates when cells were treated with tamoxifen. Furthermore, targeting ZNF703 with a mTOR inhibitor increased the inhibitory effects of tamoxifen in ZNF703-overexpressing cells.Conclusion/SignificanceOur study suggests that ZNF703 expression levels may predict tamoxifen sensitivity. Tamoxifen should be administered with caution to those patients bearing tumors with ZNF703 overexpression. However, large clinical trials and prospective clinical studies are needed to verify these results.

Gefitinib demonstrated significant antitumor activity with a favorable toxicity profile for pretreated Chinese patients with advanced NSCLC. The active mutation of the EGFR kinase domain was strongly associated with response to gefitinib and prolonged overall survival.

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