Sung‐Hyun Kim

PURPOSE: One of the main challenges of lung cancer research is identifying patients at high risk for recurrence after surgical resection. Simple, accurate, and reproducible methods of evaluating individual risks of recurrence are needed. EXPERIMENTAL DESIGN: Based on a combined analysis of time-to-recurrence data, censoring information, and microarray data from a set of 138 patients, we selected statistically significant genes thought to be predictive of disease recurrence. The number of genes was further reduced by eliminating those whose expression levels were not reproducible by real-time quantitative PCR. Within these variables, a recurrence prediction model was constructed using Cox proportional hazard regression and validated via two independent cohorts (n = 56 and n = 59). RESULTS: After performing a log-rank test of the microarray data and successively selecting genes based on real-time quantitative PCR analysis, the most significant 18 genes had P values of <0.05. After subsequent stepwise variable selection based on gene expression information and clinical variables, the recurrence prediction model consisted of six genes (CALB1, MMP7, SLC1A7, GSTA1, CCL19, and IFI44). Two pathologic variables, pStage and cellular differentiation, were developed. Validation by two independent cohorts confirmed that the proposed model is significantly accurate (P = 0.0314 and 0.0305, respectively). The predicted median recurrence-free survival times for each patient correlated well with the actual data. CONCLUSIONS: We have developed an accurate, technically simple, and reproducible method for predicting individual recurrence risks. This model would potentially be useful in developing customized strategies for managing lung cancer.

Paraxial Protocadherin (PAPC) encodes a transmembrane protein expressed initially in Spemann's organizer and then in paraxial mesoderm. Together with another member of the protocadherin family, Axial Protocadherin (AXPC), it subdivides gastrulating mesoderm into paraxial and axial domains. PAPC has potent homotypic cell adhesion activity in cell dissociation and reaggregation assays. Gain- and loss-of-function microinjection studies indicate that PAPC plays an important role in the convergence and extension movements that drive Xenopus gastrulation. Thus, PAPC is not only an adhesion molecule but also a component of the machinery that drives gastrulation movements in Xenopus. PAPC may provide a link between regulatory genes in Spemann's organizer and the execution of cell behaviors during morphogenesis.

Zebrafish paraxial protocadherin (papc) encodes a transmembrane cell adhesion molecule (PAPC) expressed in trunk mesoderm undergoing morphogenesis. Microinjection studies with a dominant-negative secreted construct suggest that papc is required for proper dorsal convergence movements during gastrulation. Genetic studies show that papc is a close downstream target of spadetail, gene encoding a transcription factor required for mesodermal morphogenetic movements. Further, we show that the floating head homeobox gene is required in axial mesoderm to repress the expression of both spadetail and papc, promoting notochord and blocking differentiation of paraxial mesoderm. The PAPC structural cell-surface protein may provide a link between regulatory transcription factors and the actual cell biological behaviors that execute morphogenesis during gastrulation.