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Intratumoral heterogeneity of cancer cells remains largely unexplored. Here we investigated the composition of ovarian cancer and its biological relevance. A whole-genome single nucleotide polymorphism array was applied to detect the clonal composition of 24 formalin-fixed, paraffin-embedded samples of human ovarian cancer. Genome-wide segmentation data consisting of the log2 ratio (log2R) and B allele frequency (BAF) were used to calculate an estimate of the clonal composition number (CC number) for each tumor. Somatic mutation profiles of cancer-related genes were also determined for the same 24 samples by next-generation sequencing. The CC number was estimated successfully for 23 of the 24 cancer samples. The mean ± SD value for the CC number was 1.7 ± 1.1 (range of 0-4). A somatic mutation in at least one gene was identified in 22 of the 24 ovarian cancer samples, with the mutations including those in the oncogenes KRAS (29.2%), PIK3CA (12.5%), BRAF (8.3%), FGFR2 (4.2%), and JAK2 (4.2%) as well as those in the tumor suppressor genes TP53 (54.2%), FBXW7 (8.3%), PTEN (4.2%), and RB1 (4.2%). Tumors with one or more oncogenic mutations had a significantly lower CC number than did those without such a mutation (1.0 ± 0.8 versus 2.3 ± 0.9, P = 0.0027), suggesting that cancers with driver oncogene mutations are less heterogeneous than those with other mutations. Our results thus reveal a reciprocal relation between oncogenic mutation status and clonal composition in ovarian cancer using the established method for the estimation of the CC number., (Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.)

The prognosis for patients with advanced esophageal or head-and-neck squamous cell carcinoma (ESCC or HNSCC) remains poor, and the identification of additional oncogenes and their inhibitors is needed. In this study, we evaluated the sensitivities of several ESCC and HNSCC cell lines to HER inhibitors (cetuximab, erlotinib, and afatinib) in vitro and found two cell lines that were hypersensitive to afatinib. Sequence analyses for the afatinib-targeted HER family genes in the two cell lines revealed that one cell line had a previously reported activating EGFR L861Q mutation, whereas the other had an HER4 G1109C mutation of unknown function. No amplification of HER family genes was found in either of the two cell lines. The phosphorylation level of HER4 was elevated in the HER4 G1109C mutation-overexpressed HEK293 cell line, and the mutation had a transforming potential and exhibited tumorigenicity in an NIH3T3 cell line, indicating that this HER4 mutation was an activating oncogenic mutation. Afatinib dramatically reduced the phosphorylation level of EGFR or HER4 and induced apoptosis in the two cell lines. In vivo, tumor growth was also dramatically decreased by afatinib. In a database, the frequencies of HER family gene mutations in ESCC or HNSCC ranged from 0% to 5%. In particular, HER4 mutations have been found relatively frequently in HNSCC. Considering the addiction of cancer cells to activating oncogenic EGFR or HER4 mutations for proliferation, HNSCC or ESCC with such oncogenic mutations might be suitable for targeted therapy with afatinib. Mol Cancer Ther; 15(8); 1988-97. ©2016 AACR., (©2016 American Association for Cancer Research.)

Most patients with non-small cell lung cancer (NSCLC) harboring common epidermal growth factor receptor (EGFR) mutations, such as deletions in exon 19 or the L858R mutation in exon 21, respond dramatically to EGFR tyrosine kinase inhibitors (EGFR-TKI), and their sensitivities to various EGFR-TKI have been well characterized. Our previous article showed the in vitro sensitivities of EGFR exon 18 mutations to EGFR-TKI, but little information regarding the sensitivities of other uncommon EGFR mutations is available. First, stable transfectant Ba/F3 cell lines harboring EGFR L858R (Ba/F3-L858R), L861Q (Ba/F3-L861Q) or S768I (Ba/F3-S768I) mutations were created and their drug sensitivities to various EGFR-TKI were examined. Both the Ba/F3-L861Q and Ba/F3-S768I cell lines were less sensitive to erlotinib, compared with the Ba/F3-L858R cell line, but their sensitivities to afatinib were similar to that of the Ba/F3-L858R cell line. The Ba/F3-L861Q cell line was similarly sensitive and the Ba/F3-S768I cell line was less sensitive to osimertinib, compared with the Ba/F3-L858R cell line. The results of western blot analyses were consistent with these sensitivities. Next, similar experiments were also performed using the KYSE270 (L861Q) and KYSE 450 (S768I) cell lines, and their results were compatible with those of the transfectant Ba/F3 cell lines. Our findings suggest that NSCLC harboring the EGFR L861Q mutation might be sensitive to afatinib or osimertinib and that NSCLC harboring the EGFR S768I mutation might be sensitive to afatinib. Overall, afatinib might be the optimal EGFR-TKI against these uncommon EGFR mutations., (© 2016 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Purpose: This study investigated whether mutations of receptor tyrosine kinase (RTK) genes detected using next-generation sequencing (NGS) are suitable therapeutic targets., Experimental Design: Fifty surgically resected non-small cell lung cancer (NSCLC) samples were target resequenced using NGS. We then investigated the functions of the identified RTK gene mutations, including their oncogenic potential, in vitro, Results: Mutations in RTK genes were found in 20 samples (EGFR, 15; ERBB4, 1; ALK, 1; DDR2, 2; FGFR1, 1), mutations in MAPK pathway genes were found in nine samples (KRAS, 7; NRAS, 1; BRAF, 2), and mutations in PI3K pathway genes were found in three samples (PIK3CA, 1; PTEN, 3). Among the mutations in RTKs, the functions of four mutations were unclear (ERBB4 D245G; DDR2 H246R and E655K; FGFR1 A263V). These mutations did not exhibit any transformational activities. Neither the phosphorylation nor the protein expressions of RTKs were changed by the DDR2 H246R, ERBB4 D245G, and FGFR1 A263V mutations, although the expression level of the DDR2 protein harboring the E655K mutation was particularly low. Collagen stimulation decreased cellular proliferation through p38 activation in the DDR2 wild-type-overexpressed cell lines, whereas the growth-suppressive effect was weakened in DDR2 E655K-overexpressed cell lines. Furthermore, the DDR2 E655K protein strongly bound to ubiquitin ligase E3 (Cbl-b), and the mutant protein expression was increased after treatment with a proteasome inhibitor., Conclusions: Our experimental findings suggest that RTK mutations are not always suitable as therapeutic targets. The DDR2 E655K mutation can play a role in cancer progression by reducing the growth-inhibitory effect of collagen. Clin Cancer Res; 22(14); 3663-71. ©2016 AACR., (©2016 American Association for Cancer Research.)

The prognosis for patients with unresectable advanced or recurrent gastric cancer remains poor. The identification of additional oncogenes with influences similar to those of epidermal growth factor receptor gene mutations, upon which the growth of cancer cells is dependent, is needed. In this study, we evaluated sensitivity to MEK inhibitors (GSK1120212 and PD0325901) in several gastric cancer cell lines in vitro and found three poorly differentiated gastric cancer cell lines that were hypersensitive to the inhibitors. The sequence analyses in these three cell lines revealed that one cell line had a novel MEK1 mutation, while the other two had previously reported KRAS and MEK1 mutations, respectively; the gene statuses of the other resistant cell lines were all wild-type. Experiments using MEK1 expression vectors demonstrated that the MEK1 mutations induced the phosphorylation of ERK1/2 and had a transforming potential, enhancing the tumorigenicity. The MEK inhibitor dramatically reduced the phosphorylation of ERK1/2 and induced apoptosis in the cell lines with MEK1 mutations. In vivo, tumor growth was also dramatically decreased by an inhibitor. One of the 46 gastric cancer clinical samples that were examined had a MEK1 mutation; this tumor had a poorly differentiated histology. Considering the addiction of cancer cells to active MEK1 mutations for proliferation, gastric cancer with such oncogenic MEK1 mutations might be suitable for targeted therapy with MEK inhibitors., (©2014 American Association for Cancer Research.)