Terra, Simone

Abstract Lung cancer accounts for about 27% of the cancer related deaths in the USA annually. Pathologically, it is a very complex disease broadly classified into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). NSCLCs are further classified into squamous cell carcinoma, large cell carcinoma and adenocarcinoma. Achaete-scute homolog 1 (ASCL1), an important transcription factor essential in the development of neuroendocrine cells (NE) in lungs is shown to be specifically expressed in lung NE cancers and 10-20% of adenocarcinomas (AD) with NE differentiation (NED), thus suggesting a role in the pathogenesis of these tumors. Our previous study showed that ASCL1 is a regulator of the RET oncogene in AD with NED. RET is a receptor tyrosine kinase with two isoforms in humans: RET9 (short) and RET51 (long). We performed survival analysis to study implications of RET isoforms in ASCL1+ tumors and found that elevated expression of the long RET mRNA was associated with poor survival. Subsequent in vitro experiments demonstrated that treatment with EGF robustly induced phosphorylation of RET in HCC1833 and H1755 cell lines which have high endogenous levels of ASCL1 and RET but not in VMRC-LCD cell line which has high level of ASCL1 but low level of RET. EGF induced phosphorylation of RET was diminished by gefitinib and by EGFR siRNA. Immunoprecipitation results indicated direct binding between EGFR and RET in presence of EGF. Furthermore, a high throughput drug screening found 8 EGFR inhibitors that were 10 - 250 fold more cytotoxic in ASCL1+ compared with ASCL1- AD cells. These results implicate EGFR as a key regulator of RET activation in ASCL1+ AD and suggest that EGFR inhibitors may be therapeutic for this population of patients. Citation Format: Kaustubh N. Bhinge, Yang Lin, Hamed Rahi, Marie Christine Aubry, Aaron Mansfield, Irina Kovtun, Stephen Murphy, Ping Yang, Dennis Wigle, Joanne (Eunhee) Yi, Aqsa Nasir, Simone Terra, Julian Molina, George Vasmatzis, Farhad Kosari. EGFR-mediated activation of RET in ASCL1+ lung adenocarcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1129.

Purpose Distinguishing independent primary tumors from intrapulmonary metastases in non–small-cell carcinoma remains a clinical dilemma with significant clinical implications. Using next-generation DNA sequencing, we developed a chromosomal rearrangement–based approach to differentiate multiple primary tumors from metastasis. Methods Tumor specimens from patients with known independent primary tumors and metastatic lesions were used for lineage test development, which was then applied to multifocal tumors. Laser capture microdissection was performed separately for each tumor. Genomic DNA was isolated using direct in situ whole-genome amplification methodology, and next-generation sequencing was performed using an Illumina mate-pair library protocol. Sequence reads were mapped to the human genome, and primers spanning the fusion junctions were used for validation polymerase chain reaction. Results A total of 41 tumor samples were sequenced (33 adenocarcinomas [ADs] and eight squamous cell carcinomas [SQCCs]), with a range of three to 276 breakpoints per tumor identified. Lung tumors predicted to be independent primary tumors based on different histologic subtype did not share any genomic rearrangements. In patients with lung primary tumors and paired distant metastases, shared rearrangements were identified in all tumor pairs, emphasizing the patient specificity of identified breakpoints. Multifocal AD and SQCC samples were reviewed independently by two pulmonary pathologists. Concordance between histology and genomic data occurred in the majority of samples. Discrepant tumor samples were resolved by genome sequencing. Conclusion A diagnostic lineage test based on genomic rearrangements from mate-pair sequencing demonstrates promise for distinguishing independent primary from metastatic disease in lung cancer.

AbstractThe development of adenocarcinoma of the lung is believed to proceed from in situ disease (adenocarcinoma in situ, AIS) to minimally invasive disease with prominent lepidic growth (minimally invasive adenocarcinoma, MIA), then to fully invasive adenocarcinoma (AD), but direct evidence for this model has been lacking. Because some lung adenocarcinomas show prominent lepidic growth (AD-L), we designed a study to address the lineage relationship between the lepidic (noninvasive) component (L) and the adjacent nonlepidic growth component representing invasive disease within individual tumors. Lineage relationships were evaluated by next-generation DNA sequencing to define large genomic rearrangements in microdissected tissue specimens collected by laser capture. We found a strong lineage relationship between the majority of adjacent lepidic and invasive components, supporting a putative AIS–AD transition. Notably, many rearrangements were detected in the less aggressive lepidic component, although the invasive component exhibited an overall higher rate of genomic rearrangement. Furthermore, a significant number of genomic rearrangements were present in histologically normal lung adjacent to tumor, but not in host germline DNA, suggesting field defects restricted to zonal regions near a tumor. Our results offer a perspective on the genetic pathogenesis underlying adenocarcinoma development and its clinical management. Cancer Res; 74(11); 3157–67. ©2014 AACR.