Complex analysis of the p53 tumor suppressor in lung carcinoma

USP28: Oncogene or Tumor Suppressor? A Unifying Paradigm for Squamous Cell Carcinoma

Squamous cell carcinomas are therapeutically challenging tumor entities. Low response rates to radiotherapy and chemotherapy are commonly observed in squamous patients and, accordingly, the mortality rate is relatively high compared to other tumor entities. Recently, targeting USP28 has been emerged as a potential alternative to improve the therapeutic response and clinical outcomes of squamous patients. USP28 is a catalytically active deubiquitinase that governs a plethora of biological processes, including cellular proliferation, DNA damage repair, apoptosis and oncogenesis. In squamous cell carcinoma, USP28 is strongly expressed and stabilizes the essential squamous transcription factor ΔNp63, together with important oncogenic factors, such as NOTCH1, c-MYC and c-JUN. It is presumed that USP28 is an oncoprotein; however, recent data suggest that the deubiquitinase also has an antineoplastic effect regulating important tumor suppressor proteins, such as p53 and CHK2. In this review, we discuss: (1) The emerging role of USP28 in cancer. (2) The complexity and mutational landscape of squamous tumors. (3) The genetic alterations and cellular pathways that determine the function of USP28 in squamous cancer. (4) The development and current state of novel USP28 inhibitors.

Somatic intronic TP53 c.375+5G mutations are a recurrent but under-recognized mode of TP53 inactivation

TP53 is one of the most ubiquitously altered genes in human cancer. The biological impact of rare variants, particularly those located within noncoding regions, remains poorly understood. From interrogation of clinical massively parallel sequencing data from over 55,000 tumors, which included 23,330 tumors with known TP53 mutations, TP53 intron 4 nucleotide substitutions at position c.375+5G were identified in 45 tumors (0.2% of TP53‐mutated cancers), comprising cancers of different organ sites. Loss‐of‐heterozygosity or a second‐hit somatic TP53 mutation was observed in 34 of 40 (85%) informative cases. RT‐PCR analysis showed the c.375+5G>T variant to be associated with aberrantly spliced TP53 mRNA transcripts with concomitant loss of the normal transcript. Immunohistochemical staining for p53 was performed on a representative subset of tumors with TP53 c.375+5G variants (n = 14), all of which showed loss of protein expression (100%; n = 13 complete loss, n = 1 subclonal loss). Our data are consistent with classification of TP53 c.375+5G variants as deleterious intronic mutations that interfere with proper mRNA splicing, ultimately resulting in loss of expression of functional p53 protein. The clinical scenario of a tumor with loss of p53 immunohistochemical staining, yet lacking a detectable TP53 exonic mutation, should therefore prompt consideration of splice‐altering intronic variants.

Clinical, Genetic, and Prognostic Features of Adrenocortical Tumors in Children: A 10-Year Single-Center Experience

Background and Aims: Pediatric adrenocortical tumors (ACTs) are very rare endocrine neoplasms in childhood. In this study, we performed a retrospective analysis of children with ACT treated at our institution by examining clinical and genetic disease features, treatment strategies, and outcomes.

Methods: We retrospectively analyzed a cohort of 13 children treated at the Bambino Gesù Children's Hospital from November 2010 to March 2020.

Results: The median age at diagnosis was 17 months (range = 0–82 months). The female: male ratio was 3.3/1. Mixed symptomatology (>1 hormone abnormality) was the most common presentation (46.1%). In three cases, the tumor was detected during prenatal or perinatal echographic screening. All patients presented with localized disease at diagnosis and underwent total adrenalectomy. Six patients were identified as having malignancies according to the Wieneke scoring system, five benign, and two undetermined. Seven patients underwent mitotane adjuvant therapy for 12 months. There was metastatic disease in three patients, with no correlation with age or Wieneke score. The most common sites of metastases were the liver and lungs. Metastatic patients were treated with surgery (n = 2), mitotane (n = 1), chemotherapy (n = 2) associated with anti-EGFR (n = 1), or immunotherapy with anti-PD1 (pembrolizumab) (n = 1); two patients achieved complete disease remission. Overall 2- and 5-year survival rates were 100%, with a median follow-up of 5 years (range = 2–9.5 years). Two- and 5-year disease free survival was 76.9 and 84.6%, respectively (95% confidence interval = −66.78–114.76 months). All patients are alive, 12 without disease, and one with stable disease. Genetic analyses showed TP53 germline mutations in six of eight patients analyzed (five inherited, one de novo). One patient had Beckwith–Wiedemann syndrome, with mosaic paternal uniparental disomy of chromosome 11, in both neoplastic and healthy adrenal tissue.

Conclusion: We report the cases of 13 patients treated for ACT, including 12 aged <4 years at diagnosis, with a relative short time from symptoms onset. Our cohort experienced an excellent prognosis. TP53 mutation was found in 75% of tested patients (6/8) confirming the need to perform genetic tests and familial counseling in this disease.

When tumor doesn't read textbook. Third case of TTF1 and p40 co-expression in the same tumour cells in a non-small cell carcinoma. A potential new entity to consider?

Introduction

The 2011 WHO Classification for lung adenocarcinoma enlightened the need for a wise use of immunohistochemistry to preserve tissue for both diagnosis and molecular studies. The current recommendation is to use a panel comprising TTF1 and p40 to classify tumors with no clear squamous or glandular differentiation as many studies have showed the higher specificity of p40 over p63 as marker of squamous differentiation. However, the co-expression of both markers opens a new scenario with subsequent classification and potentially treatment issues.

Materials and methods

We report a case of a non-small lung cell carcinoma (NSCLC) with coexistent expression of TTF1 and p40 in the same tumour cells. To our knowledge, this peculiar immunohistochemical profile is very rare, and thus a review of the clinical and molecular features including molecular variances of the tumour was performed. Review of the pertinent literature was also carried out.

Results

Two additional articles describing unusual cases of NSCLC with coexistent expression of TTF1 and p40 were found and compared to our case. Interestingly, they all carried out aberrant mutation in TP53 oncogene and were of advance stage.

Conclusion

The positivity for both “squamous” and “adenocarcinomatous” markers and mutations of TP53 could be the expression of a not fully recognized variant of NSCLC with possible implications for classification, diagnosis and therapy.

Clonal Evolution of TP53 c.375+1G>A Mutation in Pre- and Post- Neo-Adjuvant Chemotherapy (NACT) Tumor Samples in High-Grade Serous Ovarian Cancer (HGSOC)

Carboplatin/paclitaxel is the reference regimen in the treatment of advanced high-grade serous ovarian cancer (HGSOC) in neo-adjuvant chemotherapy (NACT) before interval debulking surgery (IDS). To identify new genetic markers of platinum-resistance, next-generation sequencing (NGS) analysis of 26 cancer-genes was performed on paired matched pre- and post-NACT tumor and blood samples in a patient with stage IV HGSOC treated with NACT-IDS, showing platinum-refractory/resistance and poor prognosis. Only the TP53 c.375+1G>A somatic mutation was identified in both tumor samples. This variant, associated with aberrant splicing, was in trans configuration with the 72Arg allele of the known germline polymorphism TP53 c.215C>G (p. Pro72Arg). In the post-NACT tumor sample we observed the complete expansion of the TP53 c.375+1G>A driver mutant clone with somatic loss of the treatment-sensitive 72Arg allele. NGS results were confirmed with Sanger method and immunostaining for p53, BRCA1, p16, WT1, and Ki-67 markers were evaluated. This study showed that (i) the splice mutation in TP53 was present as an early driver mutation at diagnosis; (ii) the mutational profile was shared in pre- and post-NACT tumor samples; (iii) the complete expansion of a single dominant mutant clone through loss of heterozygosity (LOH) had occurred, suggesting a possible mechanism of platinum-resistance in HGSOC under the pressure of NACT.

Knockdown of GluA2 induces apoptosis in non-small-cell lung cancer A549 cells through the p53 signaling pathway

α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are important glutamatergic receptors that mediate fast excitatory synaptic transmission in the brain. Previous studies have demonstrated that glutamate ionotropic receptor AMPA type subunit 2 (GluA2), one of the four subunits that comprise AMPA receptors, is a potential novel marker for poor prognosis in patients with human lung cancer. However, the mechanisms of GluA2-induced apoptosis, proliferation and migration in lung cancer remain unknown. The present study aimed to explore the mechanisms underlying these effects of GluA2 in human lung cancer by silencing GluA2 in A549 cells. Using the Cell Counting Kit-8 assay, western blot analysis and acridine orange/ethidium bromide staining, downregulation of GluA2 was revealed to significantly inhibit the proliferation and significantly promote the apoptosis of A549 cells. Knockdown of GluA2 was also revealed to be associated with increased caspase-3 activity, increased Bcl-2-associated X protein and Bcl-2-associated death promoter (Bad) expression, and decreased expression of B-cell lymphoma-2, p-Bad and X-linked inhibitor of apoptosis protein. In addition, GluA2 silencing upregulated cellular tumor antigen p53 (p53)/p21^Cip1/Waf1/p16^INK4a protein. In conclusion, these results indicate that the effects of GluA2 in lung cancer are mediated by the caspase-3 and p53/p21^Cip1/Waf1/p16^INK4a signaling pathways. Therefore, GluA2 may be a potential novel therapeutic target for the treatment of lung cancer.

Clinical roles of the aberrantly expressed lncRNAs in lung squamous cell carcinoma: a study based on RNA-sequencing and microarray data mining

Lung squamous cell carcinoma (LUSC) accounts for a significant proportion of lung cancer and there have been few therapeutic alternatives for recurrent LUSC due to the lack of specific driver molecules. To investigate the prospective role of lncRNAs in the tumorigenesis and progression of LUSC, the aberrantly expressed lncRNAs were calculated based on The Cancer Genome Atlas RNA-seq data. Of 7589 lncRNAs with 504 LUSC cases, 884 lncRNAs were identified as being aberrantly expressed (|log2 fold change| >2 and adjusted P<0.05) by DESeq R. The top 10 lncRNAs with the highest diagnostic value were SFTA1P,LINC00968, LINC00961, LINC01572,RP1-78O14.1, FENDRR, LINC01314,LINC01272, GATA6-AS1, and MIR3945HG. In addition to the significant roles in the carcinogenesis of LUSC, several lncRNAs also played vital parts in the survival and progression of LUSC. SFTA1P, LINC01272, GATA6-AS1 and MIR3945HG were closely related to the survival time of LUSC. Furthermore, LINC01572 and LINC01314 could distinguish the LUSC at early stage from that at advanced stage. The prospective molecular assessment of key lncRNAs showed that a certain series of genes could be involved in the regulation network. Furthermore, the OncoPrint from cBioPortal indicated that 14% (69/501) LUSC cases with genetic alterations could be obtained, including amplification, deep deletion and mRNA upregulation. More interestingly, the cases with genetic alterations had a poorer survival as compared to those without alterations. Overall, the study propounds a potentiality for interpreting the pathogenesis and development of LUSC with lncRNAs, and provides a novel platform for searching for more capable diagnostic biomarkers for LUSC.