MYCL1 Amplification and Expression of L-Myc and c-Myc in Surgically Resected Small-Cell Lung Carcinoma

C-Myc protein expression indicates unfavorable clinical outcome in surgically resected small cell lung cancer

BACKGROUND

By being highly involved in the tumor evolution and disease progression of small cell lung cancer (SCLC), Myc family members (C-Myc, L-Myc, and N-Myc) might represent promising targetable molecules. Our aim was to investigate the expression pattern and prognostic relevance of these oncogenic proteins in an international cohort of surgically resected SCLC tumors.

METHODS

Clinicopathological data and surgically resected tissue specimens from 104 SCLC patients were collected from two collaborating European institutes. Tissue sections were stained by immunohistochemistry (IHC) for all three Myc family members and the recently introduced SCLC molecular subtype-markers (ASCL1, NEUROD1, POU2F3, and YAP1).

RESULTS

IHC analysis showed C-Myc, L-Myc, and N-Myc positivity in 48%, 63%, and 9% of the specimens, respectively. N-Myc positivity significantly correlated with the POU2F3-defined molecular subtype (r = 0.6913, p = 0.0056). SCLC patients with C-Myc positive tumors exhibited significantly worse overall survival (OS) (20 vs. 44 months compared to those with C-Myc negative tumors, p = 0.0176). Ultimately, in a multivariate risk model adjusted for clinicopathological and treatment confounders, positive C-Myc expression was confirmed as an independent prognosticator of impaired OS (HR 1.811, CI 95% 1.054-3.113, p = 0.032).

CONCLUSIONS

Our study provides insights into the clinical aspects of Myc family members in surgically resected SCLC tumors. Notably, besides showing that positivity of Myc family members varies across the patients, we also reveal that C-Myc protein expression independently correlates with worse survival outcomes. Further studies are warranted to investigate the role of Myc family members as potential prognostic and predictive markers in this hard-to-treat disease.

Clinical significance of MYC family protein expression in surgically resected high-grade neuroendocrine carcinoma of the lung

OBJECTIVES

MYC family genes including MYC, MYCN, and MYCL are amplified and overexpressed as oncogenic drivers in high-grade neuroendocrine carcinoma of the lung (HGNEC), but little is known about their clinical significance. This study evaluated the prognostic impact of MYC family protein expression in patients with surgically resected HGNEC.

METHODS

Immunohistochemical analyses were performed on 83 resected specimens of HGNEC using antibodies against MYC family proteins (c-MYC, n-MYC, and l-MYC). When nuclear staining of any intensity in ≥10% of tumor cells showed immunoreactivity with any one or more of c-MYC, n-MYC, or l-MYC, the specimens were defined as MYC family-positive.

RESULTS

A total of 83 patients were analyzed. MYC family-positive status was observed in 33.7% (28 of 83 cases) and was not correlated with clinicopathological factors. The protein expression was mutually exclusive and no duplicate cases were observed. A log-rank test showed that MYC family-positive status was significantly associated with shorter overall survival (OS) (p = 0.003) and recurrence-free survival (RFS) (p = 0.039). According to Cox multivariate analysis, MYC family-positive status had a significant effect on shorter OS (hazard ratio [HR] = 2.217, 95% confidence interval [CI] 1.179-4.169, p = 0.014) and RFS (HR = 1.802, 95% CI 1.014-3.202, p = 0.045). In patients with pathological stage I, MYC family-positive status also showed significantly poor OS (HR = 2.847, 95% CI 1.236-6.557, p = 0.014) and RFS (HR = 2.088, 95% CI 1.006-4.332, p = 0.048) in the multivariate analysis.

CONCLUSIONS

MYC family protein expression could be an independent unfavorable prognostic factor in patients with surgically resected HGNEC.

Epstein-Barr Virus Infection in Lung Cancer: Insights and Perspectives

Lung cancer (LC) is the leading cause of cancer death worldwide. Tobacco smoke is the most frequent risk factor etiologically associated with LC, although exposures to other environmental factors such as arsenic, radon or asbestos are also involved. Additionally, the involvement of some viral infections such as high-risk human papillomaviruses (HR-HPVs), Merkel cell polyomavirus (MCPyV), Jaagsiekte Sheep Retrovirus (JSRV), John Cunningham Virus (JCV), and Epstein-Barr virus (EBV) has been suggested in LC, though an etiological relationship has not yet been established. EBV is a ubiquitous gamma herpesvirus causing persistent infections and some lymphoid and epithelial tumors. Since EBV is heterogeneously detected in LCs from different parts of the world, in this review we address the epidemiological and experimental evidence of a potential role of EBV. Considering this evidence, we propose mechanisms potentially involved in EBV-associated lung carcinogenesis. Additional studies are warranted to dissect the role of EBV in this very frequent malignancy.