ABT-737, a BH3 Mimetic, Enhances the Therapeutic Effects of Ionizing Radiation in K-ras Mutant Non-Small Cell Lung Cancer Preclinical Model

Purpose@#Tumor radioresistance and dose-limiting toxicity restrict the curative potential of radiotherapy, requiring novel approaches to overcome the limitations and augment the efficacy. Here, we investigated the effects of signal transducer and activator of transcription 3 (STAT3) activation and autophagy induction by irradiation on antiapoptotic proteins and the effectiveness of the BH3 mimetic ABT-737 as a radiosensitizer using K-ras mutant non-small cell lung cancer (NSCLC) cells and a Kras G12D :p53 fl/fl mouse (KP mouse) model. @*Materials and Methods@#A549 and H460 cells were irradiated, and the expression of Bcl-2 family proteins, JAK/STAT transcriptional pathway, and autophagic pathway were evaluated by immunoblotting. The radiosensitizing effects of ABT-737 were evaluated using A549 and H460 cell lines with clonogenic assays and also by a KP mouse model with microcomputed tomography and immunohistochemistry. @*Results@#In A549 and H460 cells and mouse lung tissue, irradiation-induced overexpression of the antiapoptotic molecules BclxL, Bcl-2, Bcl-w, and Mcl-1 through JAK/STAT transcriptional signaling induced dysfunction of the autophagic pathway. After treatment with ABT-737 and exposure to irradiation, the number of surviving clones in the cotreatment group was significantly lower than that in the group treated with radiation or ABT-737 alone. In the KP mouse lung cancer model, cotreatment with ABT-737 and radiation-induced significant tumor regression; however, body weight changes in the combination group were not significantly different, suggesting that combination treatment did not cause systemic toxicity. @*Conclusion@#These findings supported the radiosensitizing activity of ABT-737 in preclinical models, and suggested that clinical trials using this strategy may be beneficial in K-ras mutant NSCLC.

Methionyl-tRNA Synthetase is a Useful Diagnostic Marker for Lymph Node Metastasis in Non-Small Cell Lung Cancer

PURPOSE: Identification of lymph node (LN) metastasis in non-small cell lung cancer (NSCLC) is critical for disease staging and selection of therapeutic modalities. Sometimes it is not possible to obtain LN core tissue by endobronchial ultrasound-guided transbronchial needle aspirate (EBUS-TBNA), resulting in low diagnostic yield. MATERIALS AND METHODS: In this study, 138 specimens were collected from 108 patients who underwent EBUS-TBNA under the suspicion of LN metastasis of NSCLC. Diagnostic yields of anti-CD45 and anti-methionyl-tRNA synthetase (MRS), immunofluorescent (IF) staining on cytology specimens were compared with those of conventional cytology and positron emission tomography-computed tomography (PET-CT). RESULTS: MRS was strongly expressed in NSCLC cells metastasized to LNs, but weakly expressed in cells at the periphery of the LN germinal center. The majority of cells were CD20 positive, although a few cells were either CD3 or CD14 positive, indicating that CD45 staining is required for discrimination of non-malignant LN constituent cells from NSCLC cells. When the diagnostic efficacy of MRS/CD45 IF staining was evaluated using 138 LN cellular aspirates from 108 patients through EBUS-TBNA, the sensitivity was 76.7% and specificity was 90.8%, whereas those of conventional cytology test were 71.8% and 100.0%, respectively. Combining the results of conventional cytology testing and those of PET-CT showed a sensitivity and specificity of 71.6% and 100%, and the addition of MRS/CD45 dual IF data to this combination increased sensitivity and specificity to 85.1% and 97.8%, respectively. CONCLUSION: MRS/CD45 dual IF staining showed good diagnostic performance and may be a good tool complementing conventional cytology test for determining LN metastasis of NSCLC.

Keratinization of Lung Squamous Cell Carcinoma Is Associated with Poor Clinical Outcome / 결핵및호흡기질환

BACKGROUND: Although the World Health Organization (WHO) classification of lung squamous cell carcinoma (SCC) was revised in 2015, its clinical implications for lung SCC subsets remain unclear. We investigated whether the morphologic characteristics of lung SCC, including keratinization, were associated with clinical parameters and clinical outcome of patients. METHODS: A total of 81 patients who underwent curative surgical resection of diagnosed lung SCC, were enrolled in this study. Attributes such as keratinization, tumor budding, single cell invasion, and nuclear size within the tumor, as well as immunohistochemistry of Bcl-xL and pS6 expressions, were evaluated. RESULTS: The keratinizing and nonkeratinizing subtypes did not differ with respect to age, sex, TNM stage, and morphologic parameters such as nuclear diameter, tumor budding, and single cell invasion at the tumor edge. Most patients with the keratinizing subtype (98.0%) had a history of smoking, whereas the nonkeratinizing group had a relatively higher proportion of never-smokers relative to the keratinizing group (24.0% vs. 2.0%; p=0.008, chi-square test). Expression of pS6 (a surrogate marker of mammalian target of rapamycin complex 1 [mTORC1] signaling that regulates keratinocyte differentiation), and Bcl-xL (a key anti-apoptotic molecule that may inhibit keratinization), did not correlate significantly with the presence of keratinization. Patients with the keratinizing subtype had a significantly shorter overall survival (85.2 months vs. 135.7 months, p=0.010, log-rank test), and a multivariate analysis showed that keratinization was an independent, poor prognostic factor (hazard ratio, 2.389; 95% confidence interval, 1.090–5.233; p=0.030). CONCLUSION: In lung SCC, keratinization is associated with a poor prognosis, and might be associated with smoking.