Immunohistochemical detection of senescence markers in human sarcomas

A Conversation with ChatGPT on Contentious Issues in Senescence and Cancer Research

Artificial intelligence (AI) platforms, such as Generative Pretrained Transformer (ChatGPT), have achieved a high degree of popularity within the scientific community due to their utility in providing evidence-based reviews of the literature. However, the accuracy and reliability of the information output and the ability to provide critical analysis of the literature, especially with respect to highly controversial issues, has generally not been evaluated. In this work, we arranged a question/answer session with ChatGPT regarding several unresolved questions in the field of cancer research relating to therapy-induced senescence (TIS), including the topics of senescence reversibility, its connection to tumor dormancy, and the pharmacology of the newly emerging drug class of senolytics. ChatGPT generally provided responses consistent with the available literature, although occasionally overlooking essential components of the current understanding of the role of TIS in cancer biology and treatment. Although ChatGPT, and similar AI platforms, have utility in providing an accurate evidence-based review of the literature, their outputs should still be considered carefully, especially with respect to unresolved issues in tumor biology. SIGNIFICANCE STATEMENT: Artificial Intelligence platforms have provided great utility for researchers to investigate biomedical literature in a prompt manner. However, several issues arise when it comes to certain unresolved biological questions, especially in the cancer field. This work provided a discussion with ChatGPT regarding some of the yet-to-be-fully-elucidated conundrums of the role of therapy-induced senescence in cancer treatment and highlights the strengths and weaknesses in utilizing such platforms for analyzing the scientific literature on this topic.

Numerical assessment of the applicability of geometry-based force inference on homogeneous and heterogeneous cells

The measurement of cellular forces, which reflect crucial biological attributes, has the potential to replace conventional cell assessment methods, such as morphology, proliferation, and molecular expression analysis, in medical cell diagnosis and cell culture studies. In medical cell evaluations, force inference techniques have gained prominence due to their non-invasiveness and lack of requirement for specialized equipment. Among those techniques, the method proposed by Ishihara et al., which estimates forces in densely packed cells based only on cell geometry, is a promising method. However, its applicability range of this method has not been fully established. In this study, we employed a two-dimensional vertex model to numerically assess the applicability of this method on homogeneous and heterogeneous cells. Our comparisons between the true values from numerical simulations and the estimated values from the inference method revealed a significant correlation between estimation accuracy and cell roundness in systems of homogeneous cell. Moreover, the method demonstrated efficient force estimations in heterogeneous-cell systems. These findings may be useful when the force inference method is employed to evaluate medical cells.

Therapy-induced senescence as a component of tumor biology: Evidence from clinical cancer

Therapy-Induced Senescence (TIS) is an established response to anticancer therapy in a variety of cancer models. Ample evidence has characterized the triggers, hallmarks, and functional outcomes of TIS in preclinical studies; however, limited evidence delineates TIS in clinical cancer (human tumor samples). We examined the literature that investigated the induction of TIS in samples derived from human cancers and highlighted the major findings that suggested that TIS represents a main constituent of tumor biology. The most frequently utilized approach to identify TIS in human cancers was to investigate the protein expression of senescence-associated markers (such as cyclins, cyclin-dependent kinase inhibitors, Ki67, DNA damage repair response markers, DEC1, and DcR1) via immunohistochemical techniques using formalin-fixed paraffin-embedded (FFPE) tissue samples and/or testing the upregulation of Senescence-Associated β-galactosidase (SA-β-gal) in frozen sections of unfixed tumor samples. Collectively, and in studies where the extent of TIS was determined, TIS was detected in 31-66% of tumors exposed to various forms of chemotherapy. Moreover, TIS was not only limited to both malignant and non-malignant components of tumoral tissue but was also identified in samples of normal (non-transformed) tissue upon chemo- or radiotherapy exposure. Nevertheless, the available evidence continues to be limited and requires a more rigorous assessment of in vivo senescence based on novel approaches and more reliable molecular signatures. The accurate assessment of TIS will be beneficial for determining its relevant contribution to the overall outcome of cancer therapy and the potential translatability of senotherapeutics.

Escape from senescence: molecular basis and therapeutic ramifications

Cellular senescence constitutes a stress response mechanism in reaction to a plethora of stimuli. Senescent cells exhibit cell-cycle arrest and altered function. While cell-cycle withdrawal has been perceived as permanent, recent evidence in cancer research introduced the so-called escape-from-senescence concept. In particular, under certain conditions, senescent cells may resume proliferation, acquiring highly aggressive features. As such, they have been associated with tumour relapse, rendering senescence less effective in inhibiting cancer progression. Thus, conventional cancer treatments, incapable of eliminating senescence, may benefit if revisited to include senolytic agents. To this end, it is anticipated that the assessment of the senescence burden in everyday clinical material by pathologists will play a crucial role in the near future, laying the foundation for more personalised approaches. Here, we provide an overview of the investigations that introduced the escape-from-senescence phenomenon, the identified mechanisms, as well as the major implications for pathology and therapy. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Histological and immunohistochemical prognostic factors of primary angiosarcoma

Angiosarcoma is a malignant vascular endothelial neoplasm with various histological patterns. Despite its highly malignant potential, histological prognostic prediction has not been adopted for angiosarcoma. This study aimed to establish a method of predicting the prognosis of primary angiosarcoma. Formalin-fixed, paraffin-embedded samples from 104 primary angiosarcomas were prepared. All the cases were reviewed based on histological examinations with H&E staining. Because the French Fédération Nationale des Centres de Lutte Contre Le Cancer system (FNCLCC) is not adopted for angiosarcoma, we experimentally established a modified version of FNCLCC. Immunohistochemical staining for ERG, CD31, CD34, D2-40, HHV-8, p16, C-MYC, and p53 was performed. Fluorescence in situ hybridization (FISH) was performed for 31 cases to assay c-MYC gene amplification. Multivariate analysis revealed that age (> 70 years old) (p = 0.0011), non-cutaneous angiosarcoma (p = 0.0265), metastasis on diagnosis (p < 0.0001), size ≥ 5 cm (p = 0.0388), no taxane chemotherapy (p = 0.0388), strong nuclear atypia (p = 0.0087), and the presence of luminal structure in ≥ 50% of the tumor volume (p = 0.0009) were independent poor prognostic factors. Among angiosarcomas with luminal formation, mFNCLCC scores were significantly correlated with a poorer prognosis. The overexpression of p16 was associated with less luminal formation (p = 0.0192). Immunohistochemical analysis of C-MYC showed a moderate level of concordance with FISH (Kappa value = 0.45). This study suggested that luminal formation and nuclear atypia may be poor histological prognostic factors of angiosarcoma and that mFNCLCC would be useful for predicting the prognosis of angiosarcoma with luminal formation.

A three-marker signature identifies senescence in human breast cancer exposed to neoadjuvant chemotherapy

PURPOSE

Despite the beneficial effects of chemotherapy, therapy-induced senescence (TIS) manifests itself as an undesirable byproduct. Preclinical evidence suggests that tumor cells undergoing TIS can re-emerge as more aggressive divergents and contribute to recurrence, and thus, senolytics were proposed as adjuvant treatment to eliminate senescent tumor cells. However, the identification of TIS in clinical samples is essential for the optimal use of senolytics in cancer therapy. In this study, we aimed to detect and quantify TIS using matched breast cancer samples collected pre- and post-exposure to neoadjuvant chemotherapy (NAC).

METHODS

Detection of TIS was based on the change in gene and protein expression levels of three senescence-associated markers (downregulation of Lamin B1 and Ki-67 and upregulation of p16^INK4a).

RESULTS

Our analysis revealed that 23 of 72 (31%) of tumors had a shift in the protein expression of the three markers after exposure to NAC suggestive of TIS. Gene expression sets of two independent NAC-treated breast cancer samples showed consistent changes in the expression levels of LMNB1, MKI67 and CDKN2A.

CONCLUSIONS

Collectively, our study shows a more individualized approach to measure TIS hallmarks in matched breast cancer samples and provides an estimation of the extent of TIS in breast cancer clinically. Results from this work should be complemented with more comprehensive identification approaches of TIS in clinical samples in order to adopt a more careful implementation of senolytics in cancer treatment.

Cellular senescence in cancer: from mechanisms to detection

Senescence refers to a cellular state featuring a stable cell-cycle arrest triggered in response to stress. This response also involves other distinct morphological and intracellular changes including alterations in gene expression and epigenetic modifications, elevated macromolecular damage, metabolism deregulation and a complex pro-inflammatory secretory phenotype. The initial demonstration of oncogene-induced senescence in vitro established senescence as an important tumour-suppressive mechanism, in addition to apoptosis. Senescence not only halts the proliferation of premalignant cells but also facilitates the clearance of affected cells through immunosurveillance. Failure to clear senescent cells owing to deficient immunosurveillance may, however, lead to a state of chronic inflammation that nurtures a pro-tumorigenic microenvironment favouring cancer initiation, migration and metastasis. In addition, senescence is a response to post-therapy genotoxic stress. Therefore, tracking the emergence of senescent cells becomes pivotal to detect potential pro-tumorigenic events. Current protocols for the in vivo detection of senescence require the analysis of fixed or deep-frozen tissues, despite a significant clinical need for real-time bioimaging methods. Accuracy and efficiency of senescence detection are further hampered by a lack of universal and more specific senescence biomarkers. Recently, in an attempt to overcome these hurdles, an assortment of detection tools has been developed. These strategies all have significant potential for clinical utilisation and include flow cytometry combined with histo- or cytochemical approaches, nanoparticle-based targeted delivery of imaging contrast agents, OFF-ON fluorescent senoprobes, positron emission tomography senoprobes and analysis of circulating SASP factors, extracellular vesicles and cell-free nucleic acids isolated from plasma. Here, we highlight the occurrence of senescence in neoplasia and advanced tumours, assess the impact of senescence on tumorigenesis and discuss how the ongoing development of senescence detection tools might improve early detection of multiple cancers and response to therapy in the near future.

A Novel Lipofuscin-detecting Marker of Senescence Relates With Hypoxia, Dysregulated Autophagy and With Poor Prognosis in Non-small-cell-lung Cancer

BACKGROUND/AIM

The role of senescence in defining tumor aggressiveness at a clinical level remains obscure. A novel mixed histochemical/immunohistochemical method (SenTraGor™, STG) detecting lipofuscin accumulation allows the assessment of senescent cells in paraffin-embedded tissue material.

MATERIALS AND METHODS

STG expression was quantified in 98 surgically resected primary non-small-cell-lung carcinomas (NSCLC). Data were analyzed in parallel with other immunohistochemical markers related to hypoxia and autophagy.

RESULTS

Strong STG staining was noted in 36/98 cases (36.7%). High STG expression was significantly associated with high HIF1α expression and high expression of glucose (GLUT1) and monocarboxylate (MCT2) transporters, pointing to a link between senescence, hypoxia and glycolysis. High STG expression was also linked with high cytoplasmic accumulation of MAP1-LC3B, TFEB and LAMP2a, suggestive of a blockage of autophagy flux in tumors with intense senescence. Survival analysis showed a direct association with poor survival, independently of stage.

CONCLUSION

SenTraGor™ provides a reliable methodology to detect lipofuscin accumulation in cancer cells in paraffin-embedded tissues, opening a new field for translational studies focused on senescence.

Algorithmic assessment of cellular senescence in experimental and clinical specimens

The development of genetic tools allowed for the validation of the pro-aging and pro-disease functions of senescent cells in vivo. These discoveries prompted the development of senotherapies-pharmaceutical interventions aimed at interfering with the detrimental effect of senescent cells-that are now entering the clinical stage. However, unequivocal identification and examination of cellular senescence remains highly difficult because of the lack of universal and specific markers. Here, to overcome the limitation of measuring individual markers, we describe a detailed two-phase algorithmic assessment to quantify various senescence-associated parameters in the same specimen. In the first phase, we combine the measurement of lysosomal and proliferative features with the expression of general senescence-associated genes to validate the presence of senescent cells. In the second phase we measure the levels of pro-inflammatory markers for specification of the type of senescence. The protocol can help graduate-level basic scientists to improve the characterization of senescence-associated phenotypes and the identification of specific senescent subtypes. Moreover, it can serve as an important tool for the clinical validation of the role of senescent cells and the effectiveness of anti-senescence therapies.

Bcl-xL as a Modulator of Senescence and Aging

Many features of aging result from the incapacity of cells to adapt to stress conditions. When cells are overwhelmed by stress, they can undergo senescence to avoid unrestricted growth of damaged cells. Recent findings have proven that cellular senescence is more than that. A specific grade of senescence promotes embryo development, tissue remodeling and wound healing. However, constant stresses and a weakening immune system can lead to senescence chronicity with aging. The accumulation of senescent cells is directly related to tissue dysfunction and age-related pathologies. Centenarians, the most aged individuals, should accumulate senescent cells and suffer from their deleterious effects, however, they enjoy a compression of morbidity. We have shown that they overexpress B-cell lymphoma-extra large (Bcl-xL). Bcl-xL could avoid an excessive burden of senescent cells through the regulation of intrinsic apoptosis, mitochondrial bioenergetics and oxidative stress. On the other hand, Bcl-xL maintains a fully functional immune system that ensures an efficient clearance of senescent cells. Moreover, there is a paradox, as inhibitors of Bcl-xL have been employed as senolytic agents, which have been shown to protect from aging in animal models. In this review, we aim to discuss how Bcl-xL could modulate senescence-associated harmful effects in centenarians, protecting them from the burden of accumulation of senescent cells.