In addition, we observed that the mutation rate was significantly higher in samples with RB1 gene mutated when compared to samples with wild type RB1, suggesting that RB1 status has significant impact on the mutation profile and disease progression in SCLC.
The rate of co-occurring mutations of TP53 and RB1 in these Chinese SCLC patients was 74.6%, and lower than the reported Western patients (90.9%, P = 0.007).
Small cell lung cancer (SCLC) tumor suppressors regulate the stem cells: Rb and p53 suppress self-renewal, whereas Notch marks the stem cells and initiates deprogramming and transit amplification.
More than 90% of SCLC tumors harbor mutations in the tumor suppressor gene tumor protein p53 (p53), an important DNA damage checkpoint regulator, and these tumor cells rely predominantly on the checkpoint kinases to control DNA damage response.
The molecular drivers of neuroendocrine carcinoma are best defined in small cell lung cancer, which shows near-universal genomic alterations in TP53 and RB1.
LCNEC can be subdivided in two main subtypes: the first harboring TP53/RB1 mutations (small cell lung carcinoma (SCLC)-like), the second with mutations in TP53 and STK11/KEAP1 (non-small cell lung carcinoma (NSCLC)-like).
Through genome-scale screening for key regulators of mouse Rb1-/- Trp53-/- SCLC metastasis using the pooled CRISPR/Cas9 library, we identified Cullin5 (CUL5) and suppressor of cytokine signaling 3 (SOCS3), two components of the Cullin-RING E3 ubiquitin ligase complex, as top candidates.
In addition, a subset of <i>Rb1/Trp53/Crebbp</i>-deficient SCLC exhibited exceptional responses to Pracinostat <i>in vivo</i> Thus, CREBBP acts as a potent tumor suppressor in SCLC, and inactivation of CREBBP enhances responses to a targeted therapy.<b>Significance:</b> Our findings demonstrate that CREBBP loss in SCLC reduces histone acetylation and transcription of cellular adhesion genes, while driving tumorigenesis.
Comprehensive analysis of differential expression profiles reveals potential biomarkers associated with the cell cycle and regulated by p53 in human small cell lung cancer.
While type I LCNECs and SCLCs exhibit a neuroendocrine profile with ASCL1<sup>high</sup>/DLL3<sup>high</sup>/NOTCH<sup>low</sup>, type II LCNECs bear TP53 and RB1 alterations and differ from most SCLC tumors with reduced neuroendocrine markers, a pattern of ASCL1<sup>low</sup>/DLL3<sup>low</sup>/NOTCH<sup>high</sup>, and an upregulation of immune-related pathways.
The mutations in exon 2 of KRAS, exon 18 of DDR2, and exons 5-6 of TP53 genes were screened in lung cancer samples, including non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) using PCR and sequencing techniques.
While TP53 and RB1 alterations with secondary overexpression of p16 are mainstay events in SCLC pathogenesis, diagnostic value of p16-positivity in the diagnosis of SCLC has not yet been fully investigated.
Frequent inactivation of TP53 and RB1 as well as histone dysmodifications in SCLC suggest that transcriptional and epigenetic regulations play a major role in SCLC disease evolution.