Intratumour heterogeneity of p53 expression; causes and consequences

p53 at the crossroads of tumor immunity

The p53 tumor suppressor protein has a plethora of cell-intrinsic functions and consequences that impact diverse cell types and tissues. Recent studies are beginning to unravel how wild-type and mutant p53 work in distinct ways to modulate tumor immunity. This sets up a disequilibrium between tumor immunosurveillance and escape therefrom. The ability to exploit this emerging knowledge for translational approaches may shape immunotherapy and targeted therapeutics in the future, especially in combinatorial settings.

Understanding the complexity of p53 in a new era of tumor suppression

p53 was discovered 45 years ago as an SV40 large T antigen binding protein, coded by the most frequently mutated TP53 gene in human cancers. As a transcription factor, p53 is tightly regulated by a rich network of post-translational modifications to execute its diverse functions in tumor suppression. Although early studies established p53-mediated cell-cycle arrest, apoptosis, and senescence as the classic barriers in cancer development, a growing number of new functions of p53 have been discovered and the scope of p53-mediated anti-tumor activity is largely expanded. Here, we review the complexity of different layers of p53 regulation, and the recent advance of the p53 pathway in metabolism, ferroptosis, immunity, and others that contribute to tumor suppression. We also discuss the challenge regarding how to activate p53 function specifically effective in inhibiting tumor growth without harming normal homeostasis for cancer therapy.

P53 and VEGF are promising biomarkers for sorafenib efficacy in an experimental model of NASH-related HCC

The efficacy of systemic therapy for hepatocellular carcinoma (HCC) related to non-alcoholic steatohepatitis (NASH) is poorly understood. In this study we evaluated the effects of sorafenib based on the expression of molecular markers related to major hepatocarcinogenesis pathways and angiogenesis in a NASH-related HCC model. Forty male rats were submitted to NASH-HCC induction through the combination of a high-fat and choline deficient diet and diethylnitrosamine (100 mg/L) administration in the drinking water for 13 and 16 weeks. After the induction period, the rats received daily gavage administration of saline solution (control) or Sorafenib (5 mg/kg/day) for 3 weeks. Thereafter, the animals were euthanized and samples from liver nodules were collected for histopathological analysis and immunohistochemical assessment of HEP-PAR-1, glutamine-synthetase, VEGF, survivin, β-catenin and p53. A semi-quantitative score was used for VEGF, survivin and β-catenin analysis. For p53, the percentage of positive cells was determined. Results were processed by Wilcoxon's test or Student's t-test. Both protocols efficiently induced HCC, most of them being moderately to poorly differentiated. Sorafenib-treated animals showed a decreased expression of VEGF and p53 in HCCs generated at 13 weeks when compared to control animals (p = 0.03; p = 0.04, respectively). No significant difference in β-catenin and survivin were observed. There was a significant decrease in VEGF and p53 expression when comparing the two control groups (13 vs. 16 weeks, p < 0.01). p53 and VEGF are promising biomarkers for assessment of efficacy of Sorafenib, whereas survivin and β-catenin were not found useful. Decreased immunohistochemical expression of p53 and VEGF in the 16 week control group may indicate a different metabolic status of HCC.

Circ_0004676 exacerbates triple-negative breast cancer progression through regulation of the miR-377-3p/E2F6/PNO1 axis

BACKGROUND

The significant roles of circular RNAs (circRNAs) in different cancers and diseases have been reported. We now focused on the possible role of a newly recognized circRNA, circ_0004674 in triple-negative breast cancer (TNBC), and the related downstream mechanism.

METHODS

The expression of circ_0004674 in TNBC tissues and cells was determined followed by analysis of the correlation between circ_0004674 and TNBC patients' prognosis. The interaction between circ_0004674, miR-377-3p, E2F6, and PNO1 was then identified using bioinformatics analysis combined with FISH, RIP, RNA pull-down, RT-qPCR, and Western blot analysis. Using gain-of-function and loss-of-function methods, we analyzed the effect of circ_0004674, miR-377-3p, E2F6, and PNO1 on TNBC in vivo and in vitro.

RESULTS

Increased circ_0004674 and E2F6 but decreased miR-377-3p were observed in TNBC tissues and MDA-MB-231 TNBC cells, all of which findings were associated with poor prognosis in patients with TNBC. Silencing of circ_0004676 remarkably suppressed the proliferation, cell cycle progression, and migration of TNBC cells in vitro, as well as inhibiting tumorigenesis and metastasis in vivo. Additionally, circ_0004676 served as a sponge of miR-377-3p which bound to the transcription factor E2F6. In the presence of overexpression of circ_0004676, E2F6 expression and its target PNO1 expression were elevated, while miR-377-3p expression was decreased. Interestingly, overexpression of E2F6 could reverse the inhibitory effect on tumor growth caused by downregulation of circ_0004676.

CONCLUSION

Our study highlighted the carcinogenic effect of circ_0004676 on TNBC through regulation of the miR-377-3p/E2F6/PNO1 axis. 1. Circ_0004674 is highly expressed in TNBC tissues and cells. 2. Circ_0004674 upregulates the expression of E2F6 by sponging miR-377-3p. 3. E2F6 upregulates PNO1 by binding to the PNO1 promoter. 4. Circ_0004674 favors TNBC progression by regulating the miR-377-3p/E2F6/PNO1 axis. 5. This study provides a new target for the treatment of TNBC.

Refined criteria for p53 expression in ovarian mucinous tumours are highly concordant with TP53 mutation status, but p53 expression/TP53 status lack prognostic significance

In gynecological neoplasms, immunohistochemical (IHC) expression of p53 is generally an accurate predictor of TP53 mutation status if correctly interpreted by the pathologist. However, the literature concerning cut-offs, frequency and prognostic significance of p53 staining in ovarian mucinous tumours is limited and heterogeneous. We performed an analysis of 123 primary ovarian mucinous tumours including mucinous borderline tumours (MBT), mucinous carcinomas (MC), and tumours with equivocal features between MBT and MC. We assessed p53 expression for the three recognised patterns of aberrant staining in ovarian carcinoma [overexpression ('all'), null and cytoplasmic] but using a recently suggested cut-off for aberrant overexpression in ovarian mucinous tumours (strong nuclear p53 staining in ≥12 consecutive tumour cells) and correlated the results with next generation sequencing (NGS) in all qualitatively sufficient cases (92/123). Aberrant p53 expression was present in 25/75 (33.3%) MBT, 23/33 (69.7%) MC (75% of MC with expansile invasion and 61.5% with infiltrative invasion), and 10/15 (66.7%) tumours equivocal between MBT and MC. Regarding the 92 tumours with paired IHC and mutation results, 86 showed concordant results and six cases were discordant. Three discordant MBT cases showed aberrant expression but were TP53 wild-type on sequencing. Three cases had normal p53 expression but contained a TP53 mutation. Overall, IHC predicted the TP53 mutation status with high sensitivity (94.1%) and specificity (92.7%). The accuracy of IHC was 93.5% with a positive predictive value of 94.1% and a negative predictive value of 92.7%. When comparing MC cases with wild-type TP53 versus those with TP53 mutation, there were no significant differences concerning disease-free survival, local recurrence-free survival, or metastases-free survival (p>0.05). In the MBT subgroup, there were no events for survival analyses. In conclusion, using an independent large sample set of ovarian mucinous tumours, the results of our study confirm that the suggested refined cut-off of strong nuclear p53 staining in ≥12 consecutive tumour cells reflect high accuracy, sensitivity and specificity for an underlying TP53 mutation but the TP53 mutation status has no prognostic significance in either MC or MBT.

Protein-level mutant p53 reporters identify druggable rare precancerous clones in noncancerous tissues

Detecting and targeting precancerous cells in noncancerous tissues is a major challenge for cancer prevention. Massive stabilization of mutant p53 (mutp53) proteins is a cancer-specific event that could potentially mark precancerous cells, yet in vivo protein-level mutp53 reporters are lacking. Here we developed two transgenic protein-level mutp53 reporters, p53R172H-Akaluc and p53-mCherry, that faithfully mimic the dynamics and function of mutp53 proteins in vivo. Using these reporters, we identified and traced rare precancerous clones in deep noncancerous tissues in various cancer models. In classic mutp53-driven thymic lymphoma models, we found that precancerous clones exhibit broad chromosome number variations, upregulate precancerous stage-specific genes such as Ybx3 and enhance amino acid transport and metabolism. Inhibiting amino acid transporters downstream of Ybx3 at the early but not late stage effectively suppresses tumorigenesis and prolongs survival. Together, these protein-level mutp53 reporters reveal undercharacterized features and vulnerabilities of precancerous cells during early tumorigenesis, paving the way for precision cancer prevention.

Comparison of the International Consensus and 5th WHO edition classifications of adult myelodysplastic syndromes and acute myeloid leukemia

Several editions of the World Health Organization (WHO) classifications of lympho-hemopoietic neoplasms in 2001, 2008, and 2016 served as the international standard for diagnosis. Since the 4th WHO edition, here referred as WHO-HAEM4, significant clinico-pathological, immunophenotypic, and molecular advances have been made in the field of myeloid neoplasms, which have contributed to refine diagnostic criteria, to upgrade entities previously defined as provisional and to identify new entities. This process has resulted in two recent classification proposals of myeloid neoplasms: the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In this paper, we review and compare the two classifications in terms of diagnostic criteria and entity definition, with a focus on adult myelodysplastic syndromes/neoplasms (MDS) and acute myeloid leukemia (AML). The goal is to provide a tool to facilitate the work of pathologists, hematologists and researchers involved in the diagnosis and treatment of these hematological malignancies.

What Are the Reasons for Continuing Failures in Cancer Therapy? Are Misleading/Inappropriate Preclinical Assays to Be Blamed? Might Some Modern Therapies Cause More Harm than Benefit?

Over 50 years of cancer research has resulted in the generation of massive amounts of information, but relatively little progress has been made in the treatment of patients with solid tumors, except for extending their survival for a few months at best. Here, we will briefly discuss some of the reasons for this failure, focusing on the limitations and sometimes misunderstanding of the clinical relevance of preclinical assays that are widely used to identify novel anticancer drugs and treatment strategies (e.g., "synthetic lethality"). These include colony formation, apoptosis (e.g., caspase-3 activation), immunoblotting, and high-content multiwell plate cell-based assays, as well as tumor growth studies in animal models. A major limitation is that such assays are rarely designed to recapitulate the tumor repopulating properties associated with therapy-induced cancer cell dormancy (durable proliferation arrest) reflecting, for example, premature senescence, polyploidy and/or multinucleation. Furthermore, pro-survival properties of apoptotic cancer cells through phoenix rising, failed apoptosis, and/or anastasis (return from the brink of death), as well as cancer immunoediting and the impact of therapeutic agents on interactions between cancer and immune cells are often overlooked in preclinical studies. A brief review of the history of cancer research makes one wonder if modern strategies for treating patients with solid tumors may sometimes cause more harm than benefit.

miR-34a predicts the prognosis of advanced-stage external auditory canal squamous cell carcinoma

BACKGROUND

External auditory canal (EAC) squamous cell carcinoma (SCC) is a rare disease, and the survival rate is low in the advanced stages. It has been reported that miR-34a expression is low in many cancers and acts as a tumor suppressor, but its function in EACSCC has not yet been reported.

AIMS

To analyze the miR-34a expression levels in EACSCC specimens using in situ hybridization (ISH).

MATERIAL AND METHODS

We performed microRNA ISH for miR-34a detection and immunohistochemical analysis of p53 and Ki67 in the EACSCC and otitis externa (OE) specimens.

RESULTS

miR-34a was expressed in the basal and suprabasal layers in the OE epidermis. The pronounced expression of miR-34a was observed in the two cases of T2 (Stage II). In the one case of T3 (Stage III), it was almost the same as that of the OE. On the other hand, the expression levels of miR-34a in the one case of T3 (Stage IV) and two cases of T4 (Stage IV) were apparently reduced.

CONCLUSION

We demonstrated that the expression level of miR-34a was higher in early-stage EACSCC and lower in advanced-stage EACSCC.

SIGNIFICANCE

The expression level of miR-34a may predict a prognosis in patients with advanced-stage EACSCC.

Basal cell carcinomas acquire secondary mutations to overcome dormancy and progress from microscopic to macroscopic disease

Basal cell carcinomas (BCCs) frequently possess immense mutational burdens; however, the functional significance of most of these mutations remains unclear. Here, we report that loss of Ptch1, the most common mutation that activates upstream Hedgehog (Hh) signaling, initiates the formation of nascent BCC-like tumors that eventually enter into a dormant state. However, rare tumors that overcome dormancy acquire the ability to hyperactivate downstream Hh signaling through a variety of mechanisms, including amplification of Gli1/2 and upregulation of Mycn. Furthermore, we demonstrate that MYCN overexpression promotes the progression of tumors induced by loss of Ptch1. These findings suggest that canonical mutations that activate upstream Hh signaling are necessary, but not sufficient, for BCC to fully progress. Rather, tumors likely acquire secondary mutations that further hyperactivate downstream Hh signaling in order to escape dormancy and enter a trajectory of uncontrolled expansion.

Trieu et al. generate BCC mouse models in which rare macroscopic tumors form alongside numerous failed microscopic lesions. Successful macroscopic tumors acquire secondary changes that elevate Gli1, Gli2, and/or Mycn levels, causing hyperactivation of downstream Hedgehog (Hh) signaling. Loss of p53 and Notch1 also contributes to tumor progression.

Clinicopathologic features and lymph node metastasis pattern of the cervical MiNEN

PURPOSE

Mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) is a rare type of cervical tumor. Its clinicopathological features, lymph node (LN) metastatic patterns and outcomes are still unclear.

METHODS

We have analyzed the clinicopathological information of 26 patients with cervical MiNEN.

RESULTS

The median age of onset for cervical MiNEN was 48 years. Macroscopically, polyps and nodules were the main types. The neuroendocrine components included small cell neuroendocrine carcinoma (SCNEC) (14/26 cases), large cell neuroendocrine carcinoma (LCNEC) (10/26 cases), and typical carcinoid (2/26 cases). Non-neuroendocrine components included adenocarcinoma (AC) (12/26, including one case of AC in situ) and squamous cell carcinoma (SC) (10/26) and adeno-squamous cell carcinoma (ASC) (4/26). Of the 16 AC cases, 15 were human papilloma virus (HPV)-associated AC and one was HPV-independent AC. Except for the case of MiNEN with HPV-independent AC, all cases were diffusely and strongly positive for p16 protein. The lympho-vascular space invasion (LVSI) was seen in 17/26 cases, and the components that invade lymphatic vessels were mainly neuroendocrine carcinomas (NECs) (15/17), followed by SC (1/17) and AC (1/17). Ten patients developed LN metastases, including six in combined SCNECs (6/14) and four in combined LCNECs (4/10); the metastatic component was pure NEC in eight cases (8/10) and SC or AC in two cases (2/10).

CONCLUSIONS

NEC component is the key factor that determines the clinical behavior and prognosis of cervical MiNEN.

TP53 Copy Number and Protein Expression Inform Mutation Status across Risk Categories in Acute Myeloid Leukemia

Mutant TP53 is an adverse risk factor in acute myeloid leukemia (AML), but large-scale integrated genomic-proteomic analyses of p53 alterations in AML patients remain limited. We analyzed TP53 mutational status, copy number (CN), and protein expression data in AML (N=528) and provide a compilation of mutation sites and types across disease subgroups among treated and untreated patients. Our analysis shows differential hotspots in subsets of AML and uncovered novel pathogenic variants involving TP53 splice sites. In addition, we identified TP53 CN loss in 70.2% of TP53-mutated AML, which had more deleterious TP53 mutations and copy neutral loss of heterozygosity in 5/32 (15.6%) AML patients who had intact TP53 CN. Importantly, we demonstrate that mutant p53 protein expression patterns by immunohistochemistry evaluated using digital image-assisted analysis provide a robust readout that integrates TP53 mutation and allelic states in patients with AML (sensitivity=94.49%, specificity=90.48%). Protein expression of p53 by immunohistochemistry informed mutation status irrespective of TP53 CN status. Genomic analysis of co-mutations in TP53-mutant AML showed a muted landscape that encompassed primarily mutations in genes involved in epigenetic regulation (DNMT3A and TET2), RAS/MAPK signaling (NF1, KRAS/NRAS, PTPN11), and RNA splicing (SRSF2). In summary, our data provides a rationale to refine risk stratification of AML patients on the basis of integrated molecular and protein-level TP53 analyses.

Intratumor Heterogeneity in Hepatocellular Carcinoma: Challenges and Opportunities

Hepatocellular carcinoma (HCC) represents a leading cause of cancer-related death, but it remains difficult to treat. Intratumor genetic and phenotypic heterogeneity are inherent properties of breast, skin, lung, prostate, and brain tumors, and intratumor heterogeneity (ITH) helps define prognosis and therapeutic response in these cancers. Several recent studies estimate that ITH is inherent to HCC and attribute the clinical intractability of HCC to this heterogeneity. In this review, we examine the evidence for genomic, phenotypic, and tumor microenvironment ITH in HCC, with a focus on two of the top molecular drivers of HCC: β-catenin (CTNNB1) and Telomerase reverse transcriptase (TERT). We discuss the influence of ITH on HCC diagnosis, prognosis, and therapy, while highlighting the gaps in knowledge and possible future directions.

MIR-4507 Targets TP53 to Facilitate the Malignant Progression of Non-small-cell Lung Cancer

Lung cancer is a serious threat to human health due to its high morbidity and mortality. microRNAs (miRNAs) are involved in the tumorigenesis and progression of lung cancer. In this study, we elucidated the role of miRNA-4507 (miR-4507) in the pathogenesis of non-small-cell lung cancer (NSCLC). miR-4507 is found to be upregulated in NSCLC cells (A549, H460). MTT, 5-ethynyl-2'-deoxyuridine (EdU), wound healing, and transwell assays were performed to evaluate NSCLC cell proliferation and migration. The results demonstrated that miR-4507 inhibition significantly decrease the proliferation and migration of NSCLC cells. Subsequently, a luciferase activity assay was conducted to verify the regulation of the predicted gene target of miR-4507, namely, TP53. Mechanism experiments show that miR-4507 activates the PI3K/AKT signal. Further, we co-transfected miR-4507 mimics and TP53 plasmids and found that TP53 overexpression could recover the effects of miR-4507 mimics on proliferation, migration, and the PI3K/AKT signal activation. These results suggested that miR-4507 targets TP53 to facilitate the proliferation and migration of lung cancer cells through PI3K/AKT signal and that miR-4507 could serve as a potential target for NSCLC treatment.

The Role of p53 in Progression of Cutaneous Squamous Cell Carcinoma

Skin cancers are the most common types of cancer worldwide, and their incidence is increasing. Melanoma, basal cell carcinoma (BCC), and cutaneous squamous cell carcinoma (cSCC) are the three major types of skin cancer. Melanoma originates from melanocytes, whereas BCC and cSCC originate from epidermal keratinocytes and are therefore called keratinocyte carcinomas. Chronic exposure to ultraviolet radiation (UVR) is a common risk factor for skin cancers, but they differ with respect to oncogenic mutational profiles and alterations in cellular signaling pathways. cSCC is the most common metastatic skin cancer, and it is associated with poor prognosis in the advanced stage. An important early event in cSCC development is mutation of the TP53 gene and inactivation of the tumor suppressor function of the tumor protein 53 gene (TP53) in epidermal keratinocytes, which then leads to accumulation of additional oncogenic mutations. Additional genomic and proteomic alterations are required for the progression of premalignant lesion, actinic keratosis, to invasive and metastatic cSCC. Recently, the role of p53 in the invasion of cSCC has also been elucidated. In this review, the role of p53 in the progression of cSCC and as potential new therapeutic target for cSCC will be discussed.

Mutant p53 in cell-cell interactions

In this review, Pilley et al. examine the impact of different p53 mutations and focus on how heterogeneity of p53 status can affect relationships between cells within a tumor.

p53 is an important tumor suppressor, and the complexities of p53 function in regulating cancer cell behaviour are well established. Many cancers lose or express mutant forms of p53, with evidence that the type of alteration affecting p53 may differentially impact cancer development and progression. It is also clear that in addition to cell-autonomous functions, p53 status also affects the way cancer cells interact with each other. In this review, we briefly examine the impact of different p53 mutations and focus on how heterogeneity of p53 status can affect relationships between cells within a tumor.

Can TP53 variant negative be high-grade serous ovarian carcinoma? A case series

•

TP53 variant negative high-grade serous ovarian cancer is rare and can still show p53 abnormal immunohistochemistry.

•

Diagnostic and therapeutic considerations include pathologic, molecular and clinical domains.

•

Genetic reassessment through more comprehensive assays should be considered to ensure no missed rare or complex variants.

•

Presence of BRCA mutations can occur in TP53 variant high-grade serous ovarian cancer.

Refined cut-off for TP53 immunohistochemistry improves prediction of TP53 mutation status in ovarian mucinous tumors: implications for outcome analyses

TP53 mutations are implicated in the progression of mucinous borderline tumors (MBOT) to mucinous ovarian carcinomas (MOC). Optimized immunohistochemistry (IHC) for TP53 has been established as a proxy for the TP53 mutation status in other ovarian tumor types. We aimed to confirm the ability of TP53 IHC to predict TP53 mutation status in ovarian mucinous tumors and to evaluate the association of TP53 mutation status with survival among patients with MBOT and MOC. Tumor tissue from an initial cohort of 113 women with MBOT/MOC was stained with optimized IHC for TP53 using tissue microarrays (75.2%) or full sections (24.8%) and interpreted using established criteria as normal or abnormal (overexpression, complete absence, or cytoplasmic). Cases were considered concordant if abnormal IHC staining predicted deleterious TP53 mutations. Discordant tissue microarray cases were re-evaluated on full sections and interpretational criteria were refined. The initial cohort was expanded to a total of 165 MBOT and 424 MOC for the examination of the association of survival with TP53 mutation status, assessed either by TP53 IHC and/or sequencing. Initially, 82/113 (72.6%) cases were concordant using the established criteria. Refined criteria for overexpression to account for intratumoral heterogeneity and terminal differentiation improved concordance to 93.8% (106/113). In the expanded cohort, 19.4% (32/165) of MBOT showed evidence for TP53 mutation and this was associated with a higher risk of recurrence, disease-specific death, and all-cause mortality (overall survival: HR = 4.6, 95% CI 1.5-14.3, p = 0.0087). Within MOC, 61.1% (259/424) harbored a TP53 mutation, but this was not associated with survival (overall survival, p = 0.77). TP53 IHC is an accurate proxy for TP53 mutation status with refined interpretation criteria accounting for intratumoral heterogeneity and terminal differentiation in ovarian mucinous tumors. TP53 mutation status is an important biomarker to identify MBOT with a higher risk of mortality.

Single Cell Detection of the p53 Protein by Mass Cytometry

Simple Summary

Investigation of protein expression in cancer cells is an important part of the diagnostic process. Increasing knowledge about expression of different proteins has been exploited for prognostic assessments and in some cases also for selection of treatment. The p53 protein has proven important in development of various cancers, and the expression of this protein and its signaling pathway is therefore of interest when examining cancer patient samples. Here, we present mass cytometry as a tool for detection of p53 expression. Mass cytometry allows for measurement of up to 50 parameters per sample with single cell resolution, and we aim to demonstrate its potential for p53-focused research.

Abstract

Purpose: The p53 protein and its post-translational modifications are distinctly expressed in various normal cell types and malignant cells and are usually detected by immunohistochemistry and flow cytometry in contemporary diagnostics. Here, we describe an approach for simultaneous multiparameter detection of p53, its post-translational modifications and p53 pathway-related signaling proteins in single cells using mass cytometry. Method: We conjugated p53-specific antibodies to metal tags for detection by mass cytometry, allowing the detection of proteins and their post-translational modifications in single cells. We provide an overview of the antibody validation process using relevant biological controls, including cell lines treated in vitro with a stimulus (irradiation) known to induce changes in the expression level of p53. Finally, we present the potential of the method through investigation of primary samples from leukemia patients with distinct TP53 mutational status. Results: The p53 protein can be detected in cell lines and in primary samples by mass cytometry. By combining antibodies for p53-related signaling proteins with a surface marker panel, we show that mass cytometry can be used to decipher the single cell p53 signaling pathway in heterogeneous patient samples. Conclusion: Single cell profiling by mass cytometry allows the investigation of the p53 functionality through examination of relevant downstream signaling proteins in normal and malignant cells. Our work illustrates a novel approach for single cell profiling of p53.

The Many Uses of p53 Immunohistochemistry in Gynecological Pathology: Proceedings of the ISGyP Companion Society Session at the 2020 USCAP Annual9 Meeting

Ancillary immunohistochemistry (IHC) has become a reliable adjunct for subclassification of gynecological neoplasms. An important recent development was optimization and validation of p53 IHC, where 3 abnormal IHC patterns (nuclear overexpression, complete absence, cytoplasmic) were shown to predict underlying TP53 mutations with high accuracy in ovarian carcinomas. p53 IHC now helps in distinguishing high-grade serous from low-grade serous carcinomas. Thereafter, the new interpretation of p53 IHC was quickly adapted for other purposes and similar accuracies were shown in endometrial carcinomas, vulvar squamous cell carcinomas, and ovarian mucinous tumors. However, it required further refinement of the p53 IHC interpretation criteria for each tumor site. A proportion of endometrial endometrioid carcinomas shows an ultramutated or hypermutated genotype due to underlying POLE mutations or mismatch repair deficiency sometimes causing subclonal TP53 mutations, and their distribution can be visualized by p53 IHC. Squamous cell carcinomas and ovarian mucinous tumors show a phenomenon called terminal differentiation where basal cells demonstrate an abnormal pattern of p53 IHC but apical cells do not despite an underlying TP53 mutation. High-grade progression of adult granulosa cell tumors due to a subclonal TP53 mutation has been recently described. Another use of p53 IHC is triaging gynecological sarcomas for molecular testing based on the assumption that TP53-mutated gynecological sarcomas do not harbor cancer driving translocations. Therefore, familiarity with interpretation of p53 IHC is becoming increasingly important for the practicing gynecological pathologist. Furthermore, local optimization of the p53 IHC assay using validated protocols including appropriate low expressing control tissues (eg, tonsil) is vital in order to achieve high diagnostic accuracy, especially for abnormal staining patterns such as complete absence or cytoplasmic, and interlaboratory concordance. p53 IHC is a reliable diagnostic adjunct for histotyping and molecular subtyping of ovarian and endometrial carcinomas, and it paves the way for large-scale studies to validate the prognostic value of p53 IHC in several gynecological tumor types. The technical advances, validated interpretation criteria, and its growing versatility in identifying high-risk neoplasms paired with its widespread availability in pathology departments make p53 IHC perhaps the single most useful IHC stain in gynecological pathology.

Type 2 Diabetes Associated with Abnormal p53 Immunohistochemical Patterns in Colorectal Cancer

Abnormal p53 immunohistochemical pattern (p53-AP) including overexpression, complete absence and heterogeneity is surrogate of TP53 mutation. Using 742 cases of colorectal cancer (CRC), we show p53-AP is more common among type 2 diabetes (T2DM) patients than non-T2DM. Univariately, T2DM was significantly associated with p53-AP in overall patients, patients with microsatellite instability (MSI) stable/MSI-low phenotype or distal colorectal location. Furthermore, p53-AP was positively associated with lymph node metastasis and high TNM stage. Metformin treatment was negatively associated with p53-AP in T2DM patients. The results suggested T2DM might influence carcinogenesis, progression and prognosis via inducing TP53 mutation and abnormal p53 expression in CRC.

Emerging roles for HMGA2 in colorectal cancer

HMGA2 (High Mobility Group AT-hook 2) has been reported to promote colorectal cancer (CRC) development by regulating the transcription of target genes. It participates in nearly all aspects of cellular processes, including cell transformation, proliferation, apoptosis, senescence, metastasis, epithelial-to-mesenchymal transition (EMT), DNA repair and stem cell self-renewal. In the past decades, a group of downstream targets and binding partners have been identified in a wide range of cancers. Our findings of HMGA2 as a key factor in the MDM2/p53, IL11/STAT3 and Wnt/β-catenin signaling pathways prompt us to summarize current advances in the functional and molecular basis of HMGA2 in CRC. In this review, we address the roles of HMGA2 in the oncogenic networks of CRC based on recent advances. We review its aberrant expression, explore underlying mechanisms, discuss its pro-tumorigenic effects, and highlight promising small-molecule inhibitors based on targeting HMGA2 here. However, the understanding of HMGA2 in CRC progression is still elusive, thus we also discuss the future perspectives in this review. Collectively, this review provides novel insights into the oncogenic properties of HMGA2, which has potential implications in the diagnosis and treatment of CRC.

•

HMGA2 promotes colorectal cancer (CRC) development by regulating the transcriptions of target genes.

•

Circulating cell-free HMGA2 mRNA has been identified as a potential screening marker in CRC.

•

HMGA2 appears to be a key factor in the networks of MDM2/p53, IL11/STAT3 and Wnt/β-catenin signaling pathways in CRC.

•

Many agents and siRNAs serve as potential therapeutic approaches by targeting HMGA2 for the treatment of CRC.

•

Deciphering HMGA2-mediated machinery helps to conceive effective therapy strategies and develop novel inhibitors in CRC.

p53 immunostaining cannot be used to predict TP53 mutations in gastric cancer: results from a large Central European cohort

Four molecular subgroups of gastric cancer (GC) have been proposed, ie, Epstein-Barr virus (EBV)-positive, microsatellite instable, chromosomal instable (CIN), and genomically stable GC. Based on the complex relationship between chromosomal instability and TP53 mutational status, we hypothesized that the typical clinicopathological characteristics caused by chromosomal instability are correlated with the p53 expression that is detected by immunohistochemistry. Four hundred sixty-seven whole-tissue sections of patients with therapy-naive GC were stained with anti-p53 antibody. The histoscore and staining pattern were analyzed for each slide. Different algorithms of immunohistochemistry evaluation were formed and correlated with clinicopathological characteristics. The algorithms were validated by assessing the mutational status of TP53 in 111 cases. Four hundred forty-two GCs were p53 positive, and 25 were negative, including 414 GCs with a homogeneous pattern and 53 GCs with a heterogeneous staining pattern. There was no correlation with overall or tumor-specific survival. In comparison with clinicopathological characteristics, the algorithm high versus low showed correlations with microsatellite instability, hepatocyte growth factor receptor (MET), and TP53 mutational status. The algorithm Q1/Q4 versus Q2/Q3 appeared to be correlated with the phenotype as per the Laurén classification, microsatellite instability, EBV status, and p53 expression pattern. The algorithm <90% = 0 and <50% = 3+ versus ≥90% = 0 or ≥50% = 3+ showed correlations with the EBV status, microsatellite instability, grading, and p53 expression pattern. The algorithm homogeneous versus heterogeneous did not correlate with any clinicopathological characteristic. Our results showed that the immunohistochemistry of p53, TP53 mutational status, and CIN subtype were connected. However, different algorithms for p53 immunohistochemical evaluation cannot be used to predict TP53 mutations in CIN GCs in individual cases.

Reassessment of p53 immunohistochemistry thresholds in invasive high grade bladder cancer shows a better correlation with TP53 and FGFR3 mutations

FGFR3 mutations are frequently mutually exclusive of TP53 mutations in invasive high grade urothelial carcinoma (HGUC) and p53 immunohistochemistry is often used as a surrogate for TP53 mutations. A 10 % staining cut off has been used in HGUC for designation as p53 positive or negative however, a novel contemporary method we have previously proposed (0% or >50 % - abnormal vs. 1-49 % - wild type) has shown significant correlation with oncologic outcome as well. We aimed to compare how a ≥10 % vs. 0 % and ≥ 50 % cut off p53 assessment method correlates with TP53 and FGFR3 mutation status. Tissue microarrays created from three retrospective cohorts (two cystectomy cohorts (cohort A, n = 206 and cohort B, n = 91; one T1 transurethral resection cohort (cohort C, n = 47)) were stained with p53 and scored by two blinded reviewers using both p53 scoring schemes. 50 cases from cohort A were assessed for TP53 and FGFR3 mutation status using next generation sequencing and FGFR3 mutation status was separately assessed in cohorts B and C using SNaPshot methodology. 202 (58.7 %) and 142 (41.3 %) cases showed abnormal and wild type p53 staining, respectively. Using the 10 % cut off, 254 cases were positive (73.8 %) and 90 cases were negative (26.2 %). 27 (14.4 %) and 15 (30 %) assessed cases demonstrated FGFR3 and TP53 mutations, respectively; 19/27 FGFR3 mutated showed a wild type pattern of p53 expression while 15/15 TP53 mutated tumours showed an abnormal pattern of p53 expression. There was a significant correlation between the contemporary p53 scoring scheme and TP53 and FGFR3 mutations (p < 0.0001 and p = 0.002, respectively). Improved sensitivity, specificity, positive predictive value, and negative predictive value for TP53 mutation was also seen compared to the 10 % cut off; specifically, the sensitivity and negative predictive value were 100 %. These findings might be of clinical relevance in the era of precision medicine.

The function of a heterozygous p53 mutation in a Li-Fraumeni syndrome patient

p53 is one of the most extensively studied proteins in cancer research. Mutations in p53 generally abolish normal p53 function, and some mutants can gain new oncogenic functions. However, the mechanisms underlying p53 mutation-driven cancer remains to be elucidated. Our study investigated the function of a heterozygous p53 mutation (p.Asn268Glufs*4) in a Li-Fraumeni syndrome (LFS) patient. We used episomal technology to perform somatic reprogramming, and used molecular and cell biology methods to determine the p53 mutation levels in patient-originated induced pluripotent stem (iPS) cells at the RNA and protein levels. We found that p53 protein expression was not increased in this patient’s somatic cells compared with those of a healthy control. p53 mutation facilitates the proliferation of tumor cells by inhibiting apoptosis and promoting cell division. It can inhibit the efficiency of somatic reprogramming by inhibiting OCT4 expression during reprogramming stage. Moreover, not all p53 mutant iPS cell lines have mutant p53 RNA sequences. A small percentage of mutant p53 mRNA is present in the somatic cells from the patient and his mother. In summary, this p53 mutation can promote tumor cell proliferation, inhibit somatic reprogramming, and exhibit random p53 allelic expression of heterozygous mutations in the patient and iPS cells which may be one of the reasons why the people with p53 mutations develop cancer at random. This finding suggested that mutant p53 allelic expression should be added to the risk forecasting of cancer.

Initial Steps for the Development of a Phage-Mediated Gene Replacement Therapy Using CRISPR-Cas9 Technology

p53 gene (TP53) replacement therapy has shown promising results in cancer gene therapy. However, it has been hampered, mostly because of the gene delivery vector of choice. CRISPR-Cas9 technology (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) can knock out the mutated TP53 (mutTP53), but due to its large size, many viral vectors are not suitable or require implemented strategies that lower the therapeutic efficiency. Here, we introduced a bacteriophage or phage-based vector with the ability to target cancer cells and aimed to investigate the feasibility of using this vector to deliver CRISPR-Cas9 transgene in human lung adenocarcinoma cells. First, we produced a tumour-targeted bacteriophage carrying a CRISPR-Cas9 transgene cassette. Next, we investigated any negative impact on vector titers via quantitative polymerase chain reaction (qPCR) and colony-forming agar plate. Last, we combined Western blot analysis and immunofluorescence staining to prove cell transduction in vitro. We showed that the tumour-targeted bacteriophage can package a large-size vector genome, ~10 kb, containing the CRISPR-Cas9 sequence without any negative impact on the active or total number of bacteriophage particles. Then, we detected expression of the Cas9 in human lung adenocarcinoma cells in a targeted and efficient manner. Finally, we proved loss of p53 protein expression when a p53 gRNA was incorporated into the CRISPR-Cas9 phage DNA construct. These proof-of-concept findings support the use of engineered bacteriophage for TP53 replacement therapy in lung cancer.

Ex Vivo Organoid Cultures Reveal the Importance of the Tumor Microenvironment for Maintenance of Colorectal Cancer Stem Cells

Colorectal cancer (CRC) is a heterogeneous disease, with varying clinical presentations and patient prognosis. Different molecular subgroups of CRC should be treated differently and therefore, must be better characterized. Organoid culture has recently been suggested as a good model to reflect the heterogeneous nature of CRC. However, organoid cultures cannot be established from all CRC tumors. The study examines which CRC tumors are more likely to generate organoids and thus benefit from ex vivo organoid drug testing. Long-term organoid cultures from 22 out of 40 CRC tumor specimens were established. It was found that organoid cultures were more difficult to establish from tumors characterized as microsatellite instable (MSI), BRAF-mutated, poorly differentiated and/or of a mucinous type. This suggests that patients with such tumors are less likely to benefit from ex vivo organoid drug testing, but it may also suggest biological difference in tumor growth. RNA sequencing analysis of tumor sections revealed that the in vivo maintenance of these non-organoid-forming tumors depends on factors related to inflammation and pathogen exposure. Furthermore, using TCGA data we could show a trend towards a worse prognosis for patients with organoid-forming tumors, suggesting also clinical differences. Results suggest that organoids are more difficult to establish from tumors characterized as MSI, BRAF-mutated, poorly differentiated and/or of a mucinous type. We further suggest that the maintenance of cell growth of these tumors in vivo may be promoted by immune-related factors and other stromal components within the tumor microenvironment.

miR‑378 in combination with ultrasonic irradiation and SonoVue microbubbles transfection inhibits hepatoma cell growth

Ultrasonic microbubbles in combination with microRNA (miRNAs/miRs) exhibited promising effects on cancer treatments. The aim was to investigate the role of miR-378 in hepatoma cells and the efficiency of it in combination with ultrasonic irradiation and SonoVue^® microbubbles method for cell transfection. HuH-7, Hep3B and SK-Hep1 cells were transfected with an miR-378 mimic using only Lipofectamine^® 3000 or combined with SonoVue microbubbles and ultrasonic irradiation at 0.5 W/cm² for 30 sec. mRNAs and protein levels of Cyclin D1, Bcl-2, Bax, Akt, p53 and Survivin were detected by reverse transcription-quantitative PCR and western blotting, respectively. Cell survival rate, proliferation, cell cycle and apoptosis were determined by Cell Counting Kit-8, cell double cytochemical staining and flow cytometry, respectively. It was found that using a combination of ultrasonic irradiation and the SonoVue microbubbles method increased the effectiveness of miR-378 transfection into hepatocellular carcinoma (HCC) cells, and increased the inhibition of cell survival and proliferation. Moreover, miR-378 increased the rate of apoptosis and upregulated the expression of Bax and p53, and suppressed the cell cycle and downregulated the expression of Cyclin D1, Bcl-2, Akt, β-catenin and Survivin much more effectively in the HCC cell line by applying the combined method. Thus, miR-378 was shown to be a suppressive factor to reduce proliferation and increase apoptosis in HCC cells. Additionally, the combination of ultrasonic irradiation and SonoVue microbubbles method was more efficient in the transfection of miRNA.

MED12 exon 2 mutation is uncommon in intravenous leiomyomatosis: clinicopathologic features and molecular study

Intravenous leiomyomatosis (IVL) is a rare neoplasm that is characterized by smooth muscle cell proliferation within venous vessels. The aim of this study is to investigate the clinicopathological features, immunophenotypes, and MED12 gene mutations in IVL. Nine cases of IVL from the Affiliated Hospital of Qingdao University were collected, and the clinicopathological features were reviewed. The immunohistochemical expressions of p16, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), alpha thalassemia/mental retardation syndrome X-linked (ATRX), retinoblastoma 1 (RB1), fumarate hydratase (FH), and p53, were evaluated. The mutation status of MED12 gene exon 2 was detected by Sanger sequencing. All the 9 patients were women ranging from 32 to 58 years, and uterine leiomyomas were identified in 5 patients. Immunohistochemical staining showed that all IVL and leiomyoma samples were positive for estrogen receptor and progesterone receptor, but negative for CD34. IVL displayed similar immunostaining patterns with their uterine counterparts with focal p16 immunostaining. FH, PTEN, ATRX, and RB1 were variably positive, and p53 and Ki-67 positive rates were less than 5% in all cases. Two novel genetic variations at MED12 exon 2, a synonymous mutation c.141C>T (p.Asn47=), and an in-frame deletion mutation c.133_147del15 (p.Phe45_Pro49del) were identified in two IVL cases. One missense mutation c.131G>A (p.Gly44Asp) was identified in one uterine leiomyoma. The remaining 11 tumor samples (7 IVL cases and 4 uterine leiomyomas) showed no mutations at MED12 exon 2. Our results showed two novel MED12 mutations in IVL. The MED12 mutations are different between IVL and uterine leiomyoma. These findings indicate that IVL is a unique entity and different from uterine leiomyoma.