Probes for CDKN2A

The contribution of cellular senescence to the behavioral changes observed in the elderly remains elusive. Here, we observed that aging is associated with a decline in protein phosphatase 2A (PP2A) activity in the brains of zebrafish and mice. Moreover, drugs activating PP2A reversed age-related behavioral changes. We developed a transgenic zebrafish model to decrease PP2A activity in the brain through knockout of the ppp2r2c gene encoding a regulatory subunit of PP2A. Mutant fish exhibited the behavioral phenotype observed in old animals and premature accumulation of neural cells positive for markers of cellular senescence, including senescence-associated β-galactosidase, elevated levels cdkn2a/b, cdkn1a, senescence-associated secretory phenotype gene expression, and an increased level of DNA damage signaling. The behavioral and cell senescence phenotypes were reversed in mutant fish through treatment with the senolytic ABT263 or diverse PP2A activators as well as through cdkn1a or tp53 gene ablation. Senomorphic function of PP2A activators was demonstrated in mouse primary neural cells with downregulated Ppp2r2c. We conclude that PP2A reduction leads to neural cell senescence thereby contributing to age-related behavioral changes and that PP2A activators have senotherapeutic properties against deleterious behavioral effects of brain aging.

Lung squamous cell carcinoma (LSCC) remains a leading cause of cancer death with few therapeutic options. We characterized the proteogenomic landscape of LSCC, providing a deeper exposition of LSCC biology with potential therapeutic implications. We identify NSD3 as an alternative driver in FGFR1-amplified tumors and low-p63 tumors overexpressing the therapeutic target survivin. SOX2 is considered undruggable, but our analyses provide rationale for exploring chromatin modifiers such as LSD1 and EZH2 to target SOX2-overexpressing tumors. Our data support complex regulation of metabolic pathways by crosstalk between post-translational modifications including ubiquitylation. Numerous immune-related proteogenomic observations suggest directions for further investigation. Proteogenomic dissection of CDKN2A mutations argue for more nuanced assessment of RB1 protein expression and phosphorylation before declaring CDK4/6 inhibition unsuccessful. Finally, triangulation between LSCC, LUAD, and HNSCC identified both unique and common therapeutic vulnerabilities. These observations and proteogenomics data resources may guide research into the biology and treatment of LSCC.

There have been a few case reports and one small series of low grade papillary sinonasal (Schneiderian) carcinomas (LGPSC) which mimic papillomas but have overtly invasive growth and which occasionally metastasize. We describe the morphologic, clinical, immunohistochemical, and molecular features of five patients with LGPSC compared with eight cases each of inverted papilloma (IP) and conventional nonkeratinizing squamous cell carcinoma (SCC) with papillary growth. All LGPSC were nested with predominantly pushing invasion, no stromal reaction, and frequent surface papillary growth. All consisted of one cell type only, with polygonal cells with round nuclei, no (or limited) cytologic atypia, low mitotic activity, and prominent neutrophilic infiltrate. One patient had slightly more infiltrative bone invasion, another lymphovascular, perineural, and skeletal muscle invasion, and a third nodal metastasis after 17 years. By comparison, IPs had bland cytology, neutrophilic microabscesses, mixed immature squamous, goblet cell, and respiratory epithelium, and extremely low mitotic activity. Nonkeratinizing SCCs had basaloid-appearing cells with nuclear pleomorphism, brisk mitotic activity, and apoptosis. All LGPSC were p63 positive. Mitotic activity and Ki67 indices were significantly higher for LGPSCs than IPs and significantly lower than NKSCCs, while p53 immunohistochemistry in LGPSC was identical to nonkeratinizing SCC and higher than for IP. Sequencing showed all five tumors to harbor a MUC6 mutation, one tumor to harbor CDKN2A and PIK3R1 mutations, and one tumor to harbor a NOTCH1 mutation. All LGPSC lacked EGFR and KRAS mutations and lacked copy number variations of any main cancer genes. At a median follow up of 12 months, two LGPSC recurred locally, and one patient died after massive local recurrences and nodal metastases. LGPSC is a distinct, de novo sinonasal carcinoma that can be differentiated from papillomas by morphology and selected immunohistochemistry.

Esophageal verrucous carcinoma (VSCC) is a rare and morphologically distinct type of esophageal squamous cell carcinoma (SCC). Diagnosing VSCC on biopsy material is challenging given the lack of significant atypia and the presence of keratinizing epithelium and exophytic growth. The molecular pathogenesis of VSCC remains unclear. The aim of this study was to characterize the genomic landscape of VSCC in comparison to conventional esophageal SCC. Three cases of VSCC from the Brigham and Women's Hospital pathology archive were identified. Formalin-fixed, paraffin-embedded (FFPE) tumor tissue was used for p16 immunohistochemistry (IHC), high-risk HPV in situ mRNA hybridization (ISH), and DNA isolation. Tumor DNA was sequenced using a targeted massively parallel sequencing assay enriched for cancer-associated genes. Three additional cases of VSCC were identified by image review of The Cancer Genome Atlas (TCGA) esophageal SCC cohort. VSCC cases were negative for p16 IHC and high-risk HPV ISH. TP53 mutations (p<0.001) and copy number variants (CNVs) for CDKN2A (p<0.001), CDKN2B (p<0.01) and CCND1 (p<0.01) were absent in VSCC and significantly less frequent in comparison to conventional SCC. Five VSCC cases featured SMARCA4 missense mutations or inframe deletions compared to only 4/88 conventional SCC cases (p<0.001). VSCC featured driver mutations in PIK3CA, HRAS, and GNAS. Recurrent CNVs were rare in VSCC. VSCC is not only morphologically but also genetically distinct from conventional esophageal SCC, featuring frequent SMARCA4 mutations and infrequent TP53 mutations or CDKN2A/B CNVs. Molecular findings may aid in establishing the challenging diagnosis of VSCC. This article is protected by