The meaning of p16(ink4a) expression in tumors: functional significance, clinical associations and future developments

Genetic alterations of Cyclin D-CDK4/6-INK4-RB pathway in prostate cancer

BACKGROUND

Alterations in key cell cycle regulators are strongly linked to tumorigenesis. Therefore, we hypothesized that polymorphisms of genes encoded cyclin-dependent kinase 4 and 6 (CDK4 and CDK6), cyclin D1 (CCND1), CDK inhibitors p16INK4a and p15INK4b, as well as the retinoblastoma protein (RB), could modulate prostate cancer risk and influence the corresponding mRNA levels.

METHODS AND RESULTS

We evaluated CDK4 rs2069502, CDK6 rs2285332, CCND1 rs9344, p16INK4a rs11515, p15INK4b rs3217986, and RB rs3092904 polymorphisms using TaqMan® SNP Assays in a cohort comprising 532 prostate cancer patients and 567 control subjects. Additionally, we measured the relative mRNA expression levels of genes encoding these proteins in RNA derived from 44 prostate tumor tissues and 31 benign prostatic hyperplasia (BPH) tissues using quantitative real-time PCR (qRT-PCR). No statistically significant associations were found between the CDK4 rs2069502, p16INK4a rs11515 and RB rs3092904 polymorphisms and prostate cancer risk. However, the GA genotype of CCND1 rs9344 polymorphism was significantly associated with an increased risk of prostate cancer (OR, 1.64; 95% CI, 1.23-2.20; p < 0.001). Moreover, the relative mRNA expression levels of CCND1, p15INK4b and RB were significantly lower (p<0.05) in prostate tumor tissues compared to BPH tissues. Furthermore, lower relative expression levels of CDK4 and p16INK4a mRNA were associated with elevated serum PSA levels (≥10 ng/ml; p<0.05), while reduced relative expression of p15INK4b was correlated with a higher pathological T stage (pT3/pT4; p<0.05).

CONCLUSIONS

Our findings indicate that genetic alterations, including polymorphisms and/or gene expression changes in the cyclin D1-CDK4-p16INK4a/p15INK4b-RB pathway, are associated with prostate cancer risk.

Tumor Suppressors Condition Differential Responses to the Selective CDK2 Inhibitor BLU-222

Cyclin-dependent kinase 2 (CDK2) inhibitors have recently been developed and have entered clinical trials. Combination approaches can help broaden the use of therapeutic agents and establish more effective treatments. Here, we evaluated the selective CDK2 inhibitor BLU-222 for mechanisms of response in the context of ovarian and breast cancer models. Sensors of cellular CDK activity indicated that sensitivity to either CDK4/6 or CDK2 inhibition was related to the differential dependence on a single CDK for G1-S transition. Unlike CDK4/6 inhibitors, BLU-222 was able to robustly inhibit proliferation through cell-cycle inhibition in both G1 and G2 phases. However, it remained possible for cells to reenter the cell cycle upon drug withdrawal. The antiproliferative strength and impact on G1-S versus G2-M accumulation was mediated by the RB tumor suppressor. To broaden the sensitivity to CDK2 inhibition, combinatorial drug screens were performed that identified both synergistic (e.g., CDK4/6 inhibitors) and antagonistic (e.g., WEE1 inhibitors) relationships. Models that were exceptionally sensitive to CDK2 inhibition displayed coordinate expression of cyclin E1 and P16INK4A, an endogenous CDK4/6 inhibitor. Functional studies demonstrated that P16INK4A and CDK4/6 activity were key mediators of sensitivity to BLU-222. Clinical gene and protein expression analyses revealed a positive correlation between cyclin E1 and P16INK4A and identified that ∼25% of ovarian cancers exhibited coordinate expression of cyclin E, P16INK4A, and RB, indicative of strong sensitivity to CDK2 inhibition. Together, this work advances a precision strategy for the use of CDK2 inhibitors in the context of ovarian and breast cancers. Significance: The CDK2-specific inhibitor BLU-222 shows preclinical efficacy in breast and ovarian cancer with select determinants of response and holds promise in combinatorial strategies. See related article by House and colleagues, p. 1297.

Decoding brain aging trajectory: predictive discrepancies, genetic susceptibilities, and emerging therapeutic strategies

The global extension of human lifespan has intensified the focus on aging, yet its underlying mechanisms remain inadequately understood. The article highlights aspects of genetic susceptibility to impaired brain bioenergetics, trends in age-related gene expression related to neuroinflammation and brain senescence, and the impact of stem cell exhaustion and quiescence on accelerated brain aging. We also review the accumulation of senescent cells, mitochondrial dysfunction, and metabolic disturbances as central pathological processes in aging, emphasizing how these factors contribute to inflammation and disrupt cellular competition defining the aging trajectory. Furthermore, we discuss emerging therapeutic strategies and the future potential of integrating advanced technologies to refine aging assessments. The combination of several methods including genetic analysis, neuroimaging techniques, cognitive tests and digital twins, offer a novel approach by simulating and monitoring individual health and aging trajectories, thereby providing more accurate and personalized insights. Conclusively, the accurate estimation of brain aging trajectories is crucial for understanding and managing aging processes, potentially transforming preventive and therapeutic strategies to improve health outcomes in aging populations.

The interplay of p16INK4a and non-coding RNAs: bridging cellular senescence, aging, and cancer

p16INK4a is a crucial tumor suppressor and regulator of cellular senescence, forming a molecular bridge between aging and cancer. Dysregulated p16INK4a expression is linked to both premature aging and cancer progression, where non-coding RNAs (ncRNAs) such as long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and small interfering RNAs (siRNAs) play key roles in modulating its function. These ncRNAs interact with p16INK4a through complex post-transcriptional and epigenetic mechanisms, influencing pathways critical to senescence and tumor suppression. In this review, we explore ncRNAs, including ANRIL, MIR31HG, UCA1, MALAT1, miR-24, miR-30, and miR-141, which collectively regulate p16INK4a expression, promoting or inhibiting pathways associated with cancer and aging. ANRIL and MIR31HG modulate p16INK4a silencing via interactions with polycomb repressive complexes (PRC), while miRNAs such as miR-24 and miR-30 target p16INK4a to influence cellular proliferation and senescence. This regulatory interplay underscores the therapeutic potential of ncRNA-targeted strategies to restore p16INK4a function. We summarize recent studies supporting that ncRNAs that control p16INK4a may be diagnostic biomarkers and therapeutic targets for age-related diseases and cancer.

Early onset pancreatic cancer: A review

Early-onset pancreatic cancer (EOPC) is usually defined as patients with pancreatic cancer before the age of 50 years, which is relatively rare. However, the research on EOPC is somewhat obscure, and the specific clinical and molecular characteristics of this condition are debated. In this review, we discussed the differences between EOPC and late-onset pancreatic cancer (LOPC) or average-onset pancreatic cancer (AOPC) with a focus on clinical and molecular characteristics, survival outcomes and treatment to promote the diagnosis and treatment of EOPC.

A phase I study of the CDK4/6 inhibitor ribociclib combined with gemcitabine in patients with advanced solid tumors

BACKGROUND

Based on preclinical data showing addition of CDK4/6 inhibitors to gemcitabine was synergistic, ribociclib was evaluated in combination with gemcitabine to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLT).

METHODS

In this single arm multicohort phase I trial, we evaluated the safety and efficacy of ribociclib plus gemcitabine in patients with advanced solid tumors. Patients received gemcitabine intravenously on days 1 and 8 followed by ribociclib days 8-14, with treatment repeated every 3 weeks.

RESULTS

The study enrolled 43 patients between October 2017 and September 2019. The escalation phase (19 patients) determined the MTD and recommended phase II dose (RP2D) to be ribociclib 800 mg daily and gemcitabine 1000 mg/m2 for the expansion phase (24 patients). One patient experienced Grade 4 thrombocytopenia. Eleven patients experienced Grade 3 adverse events (AE), the most common being neutropenia, thrombocytopenia, and anemia. No partial or complete responses were observed. 15/22 (68%) of efficacy evaluable patients who received the MTD achieved best response of stable disease.

CONCLUSIONS

The addition of ribociclib to gemcitabine was tolerated well and yielded stability of tumors in both cohorts. Biomarkers such as Rb status and activity of CDK2 and CDK4/6 complexes may help to select patients who may respond better to the combination of gemcitabine and ribociclib.

CLINICAL TRIAL REGISTRATION

NCT03237390.

Integrative Multiomic Profiling of Triple-Negative Breast Cancer for Identifying Suitable Therapies

PURPOSE

Triple-negative breast cancer (TNBC) is a heterogeneous disease that carries the poorest prognosis of all breast cancers. Although novel TNBC therapies in development are frequently targeted toward tumors carrying a specific genomic, transcriptomic, or protein biomarker, it is poorly understood how these biomarkers are correlated.

EXPERIMENTAL DESIGN

To better understand the molecular features of TNBC and their correlation with one another, we performed multimodal profiling on a cohort of 95 TNBC. Our approach involved quantifying tumor-infiltrating lymphocytes through hematoxylin and eosin staining, assessing the abundance of retinoblastoma, androgen receptor, and PDL1 proteins through IHC, and carrying out transcriptomic profiling using the NanoString BC360 platform, targeted DNA sequencing on a subset of cases, as well as evaluating associations with overall survival.

RESULTS

Levels of RB1 mRNA and RB proteins are better correlated with markers of retinoblastoma functionality than RB1 mutational status. Luminal androgen receptor tumors clustered into two groups with transcriptomes that cluster with either basal or mesenchymal tumors. Tumors classified as PDL1-positive by the presence of immune or tumor cells showed similar biological characteristics. HER2-low TNBC showed no distinct biological phenotype when compared with HER2-zero. The majority of TNBC were classified as basal or HER2-enriched by PAM50, the latter showing significantly improved overall survival.

CONCLUSIONS

Our study contributes new insights into biomarker utility for identifying suitable TNBC therapies and the intercorrelations between genomic, transcriptomic, protein, and cellular biomarkers. Additionally, our rich data resource can be used by other researchers to explore the interplay between DNA, RNA, and protein biomarkers in TNBC.

p16 Immunohistochemical Patterns in Triple-Negative Breast Cancer: Clinical and Genomic Similarities of the p16 Diffuse Pattern to pRB Deficiency

INTRODUCTION

Triple-negative breast cancer (TNBC) is associated with alterations in the retinoblastoma pathway. As a consequence of retinoblastoma protein (pRB) loss, compensatory upregulation of p16 occurs due to the loss of phosphorylated pRB-mediated negative feedback on p16 expression. The aim of this study is to investigate the clinicopathological and genomic characteristics associated with the diffuse pattern of p16 immunohistochemistry (IHC) in TNBC.

METHODS

The study analyzed surgically resected TNBC for whole-exome sequencing in 113 cases and for cDNA microarray in 144 cases. The p16 IHC results were classified into two patterns: diffuse and negative/mosaic.

RESULTS

In the entire cohort (n = 257), the diffuse pattern of p16 IHC was observed in 123 (47.9%) patients and the negative/mosaic pattern in 134 (52.1%). Biallelic RB1 inactivation was observed in 14.3% of patients with the diffuse pattern. The diffuse pattern of p16 IHC showed more frequent RB1 alterations and cell cycle progression signatures, a higher Ki-67 labeling index, more frequent chromosome segment copy number changes, a higher frequency of homologous recombination deficiency high, and immune-related signatures. PIK3CA mutations were more frequent in the negative/mosaic pattern. CCND1 amplification was identified in 5 cases, all with the negative/mosaic pattern.

CONCLUSION

In TNBC, the diffuse p16 pattern shows clinical and genomic similarities to pRB-deficient tumors, suggesting shared characteristics. This suggests that p16 IHC testing may provide new therapeutic approaches, underscoring its potential clinical importance.

INTRODUCTION

Triple-negative breast cancer (TNBC) is associated with alterations in the retinoblastoma pathway. As a consequence of retinoblastoma protein (pRB) loss, compensatory upregulation of p16 occurs due to the loss of phosphorylated pRB-mediated negative feedback on p16 expression. The aim of this study is to investigate the clinicopathological and genomic characteristics associated with the diffuse pattern of p16 immunohistochemistry (IHC) in TNBC.

METHODS

The study analyzed surgically resected TNBC for whole-exome sequencing in 113 cases and for cDNA microarray in 144 cases. The p16 IHC results were classified into two patterns: diffuse and negative/mosaic.

RESULTS

In the entire cohort (n = 257), the diffuse pattern of p16 IHC was observed in 123 (47.9%) patients and the negative/mosaic pattern in 134 (52.1%). Biallelic RB1 inactivation was observed in 14.3% of patients with the diffuse pattern. The diffuse pattern of p16 IHC showed more frequent RB1 alterations and cell cycle progression signatures, a higher Ki-67 labeling index, more frequent chromosome segment copy number changes, a higher frequency of homologous recombination deficiency high, and immune-related signatures. PIK3CA mutations were more frequent in the negative/mosaic pattern. CCND1 amplification was identified in 5 cases, all with the negative/mosaic pattern.

CONCLUSION

In TNBC, the diffuse p16 pattern shows clinical and genomic similarities to pRB-deficient tumors, suggesting shared characteristics. This suggests that p16 IHC testing may provide new therapeutic approaches, underscoring its potential clinical importance.

Multimodal assessment of high-risk human papillomavirus in sinonasal squamous cell carcinoma

High-risk human papillomavirus (hrHPV) is an emerging risk factor for sinonasal squamous cell carcinoma (SNSCC). The goal of this study was to assess the prevalence of hrHPV and subtype distribution in SNSCC and correlation with patient and clinical characteristics. This retrospective cohort study included 43 cases diagnosed with incident primary SNSCC at the University of Cincinnati Medical Center from 2010 to 2015. The prevalence of hrHPV was interrogated using a multi-assay approach that included p16 immunohistochemistry (IHC), RNA in-situ hybridization (ISH), and hrHPV DNA sequencing. The association of hrHPV with 5-year overall survival (OS) and 2-year disease-free survival (DFS) was assessed. Fourteen cases (32.6 %) were classified as hrHPV positive, based on the a priori definition of having either a positive RNAScope™ ISH test or hrHPV DNA and p16-positive IHC; 9 cases (20.9 %) were positive for all three tests. All cases that arose from an inverted sinonasal papilloma (ex-ISP) were negative for hrHPV. HPV16 was the most common subtype among hrHPV positive cases (58.8 %), followed by HPV18 (17.6 %). No significant association was observed between hrHPV and OS or DFS after adjusting for potential confounding. hrHPV is prevalent in a sizable fraction of SNSCC. Additional studies are needed to better elucidate the relationship with patient survival outcomes and determine the optimal testing modality for prognostication.

Cancer takes many paths through G1/S

In the commonly accepted paradigm for control of the mammalian cell cycle, sequential cyclin-dependent kinase (CDK) and cyclin activities drive the orderly transition from G1 to S phase. However, recent studies using different technological approaches and examining a broad range of cancer cell types are challenging this established paradigm. An alternative model is evolving in which cell cycles utilize different drivers and take different trajectories through the G1/S transition. We are discovering that cancer cells in particular can adapt their drivers and trajectories, which has important implications for antiproliferative therapies. These studies have helped to refine an understanding of how CDK inhibition impinges on proliferation and have significance for understanding fundamental features of cell biology and cancer.

Evolving concepts in meningioma management in the era of genomics

Meningioma is the most common type of primary brain tumor. Surgical resection followed by surveillance is the first-line treatment for the majority of symptomatic meningiomas; however, recent advances in molecular sequencing, DNA methylation, proteomics, and single-cell sequencing provide insights into further characterizing this heterogeneous group of tumors with a wide range of prognoses. A subset of these tumors are highly aggressive and cause severe morbidity and mortality. Therefore, identifying those individuals with a poor prognosis and intervening are critical. This review aims to help readers interpret the molecular profiling of meningiomas to identify patients with worse prognoses and guide the management and strategy for surveillance.

Strategy of combining CDK4/6 inhibitors with other therapies and mechanisms of resistance

Cell cycle-dependent protein kinase 4/6 (CDK4/6) is a crucial kinase that regulates the cell cycle, essential for cell division and proliferation. Hence, combining CDK4/6 inhibitors with other anti-tumor drugs is a pivotal clinical strategy. This strategy can efficiently inhibit the growth and division of tumor cells, reduce the side effects, and improve the quality of life of patients by reducing the dosage of combined anticancer drugs. Furthermore, the combination therapy strategy of CDK4/6 inhibitors could ameliorate the drug resistance of combined drugs and overcome the CDK4/6 resistance caused by CDK4/6 inhibitors. Various tumor treatment strategies combined with CDK4/6 inhibitors have entered the clinical trial stage, demonstrating their substantial clinical potential. This study reviews the research progress of CDK4/6 inhibitors from 2018 to 2022, the related resistance mechanism of CDK4/6 inhibitors, and the strategy of combination medication.

Cuproptosis in lung cancer: mechanisms and therapeutic potential

Cuproptosis, a recently identified form of cell death that differs from other forms, is induced by the disruption of the binding of copper to mitochondrial respiratory acylation components. Inducing cell cuproptosis and targeting cell copper death pathways are considered potential directions for treating tumor diseases. We have provided a detailed introduction to the metabolic process of copper. In addition, this study attempts to clarify and summarize the relationships between cuproptosis and therapeutic targets and signaling pathways of lung cancer. This review aims to summarize the theoretical achievements for translating the results of lung cancer and cuproptosis experiments into clinical treatment.

A Phase I Study of sequences of the CDK4/6 Inhibitor, Ribociclib Combined with Gemcitabine in Patients with Advanced Solid Tumors

Background

Based on preclinical data showing addition of CDK4/6 inhibitors to gemcitabine is synergistic, ribociclib was evaluated in combination with gemcitabine to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLT).

Methods

In this single arm multicohort phase I trial, we evaluated the safety and efficacy of Ribociclib plus Gemcitabine in patients with advanced solid tumors. Patients received Gemcitabine intravenously on days 1 and 8 followed by Ribociclib days 8-14, with treatment repeated every 3 weeks.

Results

The study enrolled 43 patients between October 2017 and September 2019. The escalation phase (19 patients) determined the MTD and recommended phase II dose (RP2D) to be ribociclib 800mg daily and gemcitabine 1000mg/m2 for the expansion phase (24 patients). One patient experienced Grade 4 thrombocytopenia. Eleven patients experienced Grade 3 adverse events (AE), the most common being neutropenia, thrombocytopenia, and anemia. No partial or complete responses were observed. 15/22 (68%) of efficacy evaluable patients who received the MTD achieved best response of stable disease.

Conclusions

The addition of Ribociclib to Gemcitabine was tolerated well and yielded stability of tumors in both cohorts. Ribociclib and gemcitabine could have synergistic activity in certain tumor types, and our data provides support for the combination.

Clinical Trial Registration

NCT03237390.

Preclinical evaluation of CDK4 phosphorylation predicts high sensitivity of pleural mesotheliomas to CDK4/6 inhibition

Malignant pleural mesothelioma (MPM) is an aggressive cancer with limited therapeutic options. We evaluated the impact of CDK4/6 inhibition by palbociclib in 28 MPM cell lines including 19 patient-derived ones, using various approaches including RNA-sequencing. Palbociclib strongly and durably inhibited the proliferation of 23 cell lines, indicating a unique sensitivity of MPM to CDK4/6 inhibition. When observed, insensitivity to palbociclib was mostly explained by the lack of active T172-phosphorylated CDK4. This was associated with high p16INK4A (CDKN2A) levels that accompany RB1 defects or inactivation, or (unexpectedly) CCNE1 overexpression in the presence of wild-type RB1. Prolonged palbociclib treatment irreversibly inhibited proliferation despite re-induction of cell cycle genes upon drug washout. A senescence-associated secretory phenotype including various potentially immunogenic components was irreversibly induced. Phosphorylated CDK4 was detected in 80% of 47 MPMs indicating their sensitivity to CDK4/6 inhibitors. Its absence in some highly proliferative MPMs was linked to very high p16 (CDKN2A) expression, which was also observed in public datasets in tumours from short-survival patients. Our study supports the evaluation of CDK4/6 inhibitors for MPM treatment, in monotherapy or combination therapy.

Genetic Signature of Human Pancreatic Cancer and Personalized Targeting

Pancreatic cancer is a highly lethal disease with a 5-year survival rate of around 11-12%. Surgery, being the treatment of choice, is only possible in 20% of symptomatic patients. The main reason is that when it becomes symptomatic, IT IS the tumor is usually locally advanced and/or has metastasized to distant organs; thus, early diagnosis is infrequent. The lack of specific early symptoms is an important cause of late diagnosis. Unfortunately, diagnostic tumor markers become positive at a late stage, and there is a lack of early-stage markers. Surgical and non-surgical cases are treated with neoadjuvant and/or adjuvant chemotherapy, and the results are usually poor. However, personalized targeted therapy directed against tumor drivers may improve this situation. Until recently, many pancreatic tumor driver genes/proteins were considered untargetable. Chemical and physical characteristics of mutated KRAS are a formidable challenge to overcome. This situation is slowly changing. For the first time, there are candidate drugs that can target the main driver gene of pancreatic cancer: KRAS. Indeed, KRAS inhibition has been clinically achieved in lung cancer and, at the pre-clinical level, in pancreatic cancer as well. This will probably change the very poor outlook for this disease. This paper reviews the genetic characteristics of sporadic and hereditary predisposition to pancreatic cancer and the possibilities of a personalized treatment according to the genetic signature.

Expression of p16 Tumor Suppressor Protein in Malignant Ovarian Germ Cell Tumors; Immunohistochemical Study

BACKGROUND

Malignant ovarian germ cell tumors represent small percentage of malignant ovarian neoplasms but they affect significantly young age group.

AIM OF THE STUDY

To investigate the immunohistochemical expression of p16 tumor suppressor protein in malignant ovarian germ cell tumors.

MATERIALS AND METHODS

Twenty-two malignant ovarian germ cell tumors (five dysgerminoma, eight immature teratoma, and nine yolk sac tumors), twenty mature cystic teratoma tumors and twenty normal ovarian tissue were immunohistochemically stained with p16 monoclonal antibody. Ki67 immunohistochemical staining was done for malignant ovarian germ cell tumors to assess proliferation.

RESULTS

We found that p16 tumor suppressor protein is overexpressed in all malignant ovarian germ cell tumors in both nuclear and cytoplasmic locations compared to control and to mature cystic teratoma (p-value <0.001). Cytoplasmic p16 expression was significantly correlated to Ki67 proliferation index in malignant ovarian germ cell tumors (p-value = 0.033, r = 0.445).

CONCLUSION

Overexpression of p16 in malignant ovarian germ cell tumors denotes that dysfunction of the cyclin dependent kinase pathway is involved in tumorigenesis of malignant ovarian germ cell tumors.

Altered p53/p16 expression is linked to urothelial carcinoma progression but largely unrelated to prognosis in muscle-invasive tumors

BACKGROUND

Most inactivating p53 mutations result in a nuclear p53 accumulation - detectable by immunohistochemistry (IHC). p53 alterations leading to a complete lack of p53 protein and absence of immunostaining do also occur - not easily detectable by IHC. p16 is upregulated in p53 inactivated cells. We hypothesized that a positive p16 IHC may help to distinguish p53 inactivation in IHC negative cases.

MATERIAL AND METHODS

We investigated p53 and p16 immunostaining on 2710 urothelial bladder carcinomas in a tissue microarray format to understand their impact in relation to clinicopathological parameters of disease progression and patient outcome.

RESULTS

p16 immunostaining was absent in normal urothelium but occurred in 63.5% (30.4% strong) of cancers. p16 strongly positive cases increased from pTaG2 low-grade (9.6%) to pTaG3 high-grade tumors (46.5%, p < .0001) but decreased from pTaG3 to pT4 (33.3%; p = .0030). Among pT2-4 carcinomas, p16 positivity was linked to high-grade (p = .0005) but unrelated to overall survival. p53 staining was negative in 8.4%, very weak in 15.4%, weak in 55.3%, strong in 4.7%, and very strong in 16.2% cancers. p53 negative (potentially p53 null phenotype), strong, and very strong p53 positivity increased from pTaG2 low-grade to pTaG3 high-grade tumors (p < .0001) and from pTaG3 to pT2-4 cancers (p = .0007). p53 staining was largely unrelated to histopathological parameters or patient prognosis among pT2-4 carcinomas, except of p53 strong/very strong immunostaining. p16 expression predominated in tumors with very strong, strong, and negative p53 staining and the combination of p53 negative/p16 strongly positive cancers was linked to features of tumor aggressiveness.

CONCLUSION

Aberrant p53 and p16 immunostaining increases during grade and stage progression although p53 negative and p16 positive immunostaining lack prognostic significance in pT2-4 carcinomas. Potential diagnostic features are that high level p16 expression is limited to neoplastic urothelium and p53 null phenotype to aggressive cancers (grade 3 and invasive).

CDK4 phosphorylation status and rational use for combining CDK4/6 and BRAF/MEK inhibition in advanced thyroid carcinomas

Background

CDK4/6 inhibitors (CDK4/6i) have been established as standard treatment against advanced Estrogen Receptor-positive breast cancers. These drugs are being tested against several cancers, including in combinations with other therapies. We identified the T172-phosphorylation of CDK4 as the step determining its activity, retinoblastoma protein (RB) inactivation, cell cycle commitment and sensitivity to CDK4/6i. Poorly differentiated (PDTC) and anaplastic (ATC) thyroid carcinomas, the latter considered one of the most lethal human malignancies, represent major clinical challenges. Several molecular evidence suggest that CDK4/6i could be considered for treating these advanced thyroid cancers.

Methods

We analyzed by two-dimensional gel electrophoresis the CDK4 modification profile and the presence of T172-phosphorylated CDK4 in a collection of 98 fresh-frozen tissues and in 21 cell lines. A sub-cohort of samples was characterized by RNA sequencing and immunohistochemistry. Sensitivity to CDK4/6i (palbociclib and abemaciclib) was assessed by BrdU incorporation/viability assays. Treatment of cell lines with CDK4/6i and combination with BRAF/MEK inhibitors (dabrafenib/trametinib) was comprehensively evaluated by western blot, characterization of immunoprecipitated CDK4 and CDK2 complexes and clonogenic assays.

Results

CDK4 phosphorylation was detected in all well-differentiated thyroid carcinomas (n=29), 19/20 PDTC, 16/23 ATC and 18/21 thyroid cancer cell lines, including 11 ATC-derived ones. Tumors and cell lines without phosphorylated CDK4 presented very high p16CDKN2A levels, which were associated with proliferative activity. Absence of CDK4 phosphorylation in cell lines was associated with CDK4/6i insensitivity. RB1 defects (the primary cause of intrinsic CDK4/6i resistance) were not found in 5/7 tumors without detectable phosphorylated CDK4. A previously developed 11-gene expression signature identified the likely unresponsive tumors, lacking CDK4 phosphorylation. In cell lines, palbociclib synergized with dabrafenib/trametinib by completely and permanently arresting proliferation. These combinations prevented resistance mechanisms induced by palbociclib, most notably Cyclin E1-CDK2 activation and a paradoxical stabilization of phosphorylated CDK4 complexes.

Conclusion

Our study supports further clinical evaluation of CDK4/6i and their combination with anti-BRAF/MEK therapies as a novel effective treatment against advanced thyroid tumors. Moreover, the complementary use of our 11 genes predictor with p16/KI67 evaluation could represent a prompt tool for recognizing the intrinsically CDK4/6i insensitive patients, who are potentially better candidates to immediate chemotherapy.

Determinants of response to CDK4/6 inhibitors in the real-world setting

Despite widespread use and a known mechanism of action for CDK4/6 inhibitors in combination with endocrine therapy, features of disease evolution and determinants of therapeutic response in the real-world setting remain unclear. Here, a cohort of patients treated with standard-of-care combination regimens was utilized to explore features of disease and determinants of progression-free survival (PFS) and overall survival (OS). In this cohort of 280 patients, >90% of patients were treated with palbociclib in combination with either an aromatase inhibitor (AI) or fulvestrant (FUL). Most of these patients had modified Scarff-Bloom-Richardson (SBR) scores, and ER, HER2, and PR immunohistochemistry. Both the SBR score and lack of PR expression were associated with shorter PFS in patients treated with AI combinations and remained significant in multivariate analyses (HR = 3.86, p = 0.008). Gene expression analyses indicated substantial changes in cell cycle and estrogen receptor signaling during the course of treatment. Furthermore, gene expression-based subtyping indicated that predominant subtypes changed with treatment and progression. The luminal B, HER2, and basal subtypes exhibited shorter PFS in CDK4/6 inhibitor combinations when assessed in the pretreatment biopsies; however, they were not associated with OS. Using unbiased approaches, cell cycle-associated gene sets were strongly associated with shorter PFS in pretreatment biopsies irrespective of endocrine therapy. Estrogen receptor signaling gene sets were associated with longer PFS particularly in the AI-treated cohort. Together, these data suggest that there are distinct pathological and biological features of HR+/HER2- breast cancer associated with response to CDK4/6 inhibitors. Clinical trial registration number: NCT04526587.

Preferential killing of melanoma cells by a p16-related peptide

We report the identification of a synthetic, cell-penetrating peptide able to kill human melanoma cells efficiently and selectively, while being less toxic to normal human melanocytes and nontoxic to human fibroblasts. The peptide is based on the target-binding site of the melanoma suppressor and senescence effector p16 (also known as INK4A or CDKN2A), coupled to a cell-penetrating moiety. The killing is by apoptosis and appears to act by a route other than the canonical downstream target of p16 and CDK4, the retinoblastoma (RB) protein family, as it is also effective in HeLa cells and a melanocyte line expressing HPV E7 oncogenes, which both lack any active RB. There was varying toxicity to other types of cancer cell lines, such as glioblastoma. Melanoma cell killing by a p16-derived peptide was reported once before but only at a higher concentration, while selectivity and generality were not previously tested.

Lessons and Opportunities for Biomarker-Driven Radiation Personalization in Head and Neck Cancer

Head and neck cancer is notoriously challenging to treat in part because it constitutes an anatomically and biologically diverse group of cancers with heterogeneous prognoses. While treatment can be associated with significant late toxicities, recurrence is often difficult to salvage with poor survival rates and functional morbidity.^1,2 Thus, achieving tumor control and cure at the initial diagnosis is the highest priority. Given the differing outcome expectations (even within a specific sub-site like oropharyngeal carcinoma), there has been growing interest in personalizing treatment: de-escalation in selected cancers to decrease the risk of late toxicity without compromising oncologic outcomes, and intensification for more aggressive cancers to improve oncologic outcomes without causing undue toxicity. This risk stratification is increasingly accomplished using biomarkers, which can represent molecular, clinicopathologic, and/or radiologic data. In this review, we will focus on biomarker-driven radiotherapy dose personalization with emphasis on oropharyngeal and nasopharyngeal carcinoma. This radiation personalization is largely performed on the population level by identifying patients with good prognosis via traditional clinicopathologic factors, although there are emerging studies supporting inter-tumor and intra-tumor level personalization via imaging and molecular biomarkers.

Paternal Combined Botanicals Contribute to the Prevention of Estrogen Receptor-Negative Mammary Cancer in Transgenic Mice

BACKGROUND

Parental nutritional interventions have considerably affected gametogenesis and embryogenesis, leading to the differential susceptibility of offspring to chronic diseases such as cancer. Moreover, combinatorial bioactive diets are more efficacious in ameliorating epigenetic aberrations in tumorigenesis.

OBJECTIVES

We sought to investigate the transgenerational influence and epigenetic regulation of paternal sulforaphane (SFN)-rich broccoli sprouts (BSp) and epigallocatechin-3-gallate (EGCG)-rich green tea polyphenols (GTPs) consumption in the prevention of estrogen receptor-negative [ER(-)] mammary cancer in transgenic mice.

METHODS

Human breast cancer cells were used to detect cell viability and epigenetic-related gene expression after treatment with EGCG and/or SFN. Twenty-four C3 or HER2/neu males were randomly assigned into 4 groups and treated with control, 26% BSp (w/w) in food, 0.5% GTPs (w/v) in drinking water or combined BSp and GTPs for 7 wk before mating. Tumor growth of nontreated female pups was monitored weekly for 19 wk (C3) and 25 wk (HER2/neu). Tumor- and epigenetic-related protein expression and enzyme activities in mammary tumors were measured. Sperms were isolated from treated males for RNA sequencing and reduced-representation bisulfite sequencing analysis. Data were analyzed with a 2-factor or 3-factor analysis of variance.

RESULTS

EGCG and SFN inhibited breast cancer cell growth via epigenetic regulation. Combined BSp and GTPs synergistically (combination index < 1) suppressed tumor growth over time (P < 0.001) in 2 mouse models. Key tumor-related proteins were found differentially expressed (P < 0.05) along with epigenetic regulations in offspring mammary tumors. The transcriptome profile of sperm derived from dietary-treated males revealed differentially expressed genes correlated with spermatogenesis and breast cancer progression. DNA methylomes of the sperm and further integrated analysis with transcriptomes indicate that DNA methylation alone may not contribute to sufficient regulation in dietary-treated sperm pronucleus, leading to offspring tumor suppression.

CONCLUSIONS

Collectively, paternal consumption of combined BSp and GTPs shows potential for preventing ER(-) mammary cancer through transgenerational effects. J Nutr 2023;xx:xx-xx.

Targeting cyclin-dependent kinases in rheumatoid arthritis and psoriasis - a review of current evidence

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with synovial proliferation and bone erosion, which leads to the structural and functional impairment of the joints. Immune cells, together with synoviocytes, induce a pro-inflammatory environment and novel treatment agents target inflammatory cytokines. Psoriasis is a chronic immune-mediated skin disease, and several cytokines are considered as typical mediators in the progression of the disease, including IL-23, IL-22, and IL-17, among others.

AREA COVERED

In this review, we try to evaluate whether cyclin-dependent kinases (CDK), enzymes that regulate cell cycle and transcription of various genes, could become novel therapeutic targets in RA and psoriasis. We present the main results of in vitro and in vivo studies, as well as scarce clinical reports.

EXPERT OPINION

CDK inhibitors seem promising for treating RA and psoriasis because of their multidirectional effects. CDK inhibitors may affect not only the process of osteoclastogenesis, thereby reducing joint destruction in RA, but also the process of apoptosis of neutrophils and macrophages responsible for the development of inflammation in both RA and psoriasis. However, assessing the efficacy of these drugs in clinical practice requires multi-center, long-term clinical trials evaluating the effectiveness and safety of CDK-blocking therapy in RA and psoriasis.

Expression analysis of cell cycle related lncRNAs in breast cancer tissues

Cell cycle regulation is an important cellular function. Abnormal regulation of this process can cause cancer. Several genes are involved in this process. There is no comprehensive study on expression pattern of cell cycle related lncRNAs in breast cancer patients. In the current study, we evaluated expressions of LINC00668, PRDM16-DT, SNHG7 and CDKN2A in 42 pairs of breast cancer tissues and adjacent non-tumoral tissues. Expression of SNHG7 was significantly lower in tumoral tissues compared with non-tumoral tissues. However, expressions of LINC00668, PRDM16-DT and CDKN2A were not significantly different between these two sets of samples. Expression levels of SNHG7 could separate tumoral tissues from non-tumoral tissues with AUC value= 0.66, sensitivity= 61% and specificity= 73%. Expression of CDKN2A was associated with clinical stage (P value=0.01). Expression levels of LINC00668, PRDM16-DT, SNHG7 and CDKN2A were higher in estrogen receptor (ER) positive samples compared with ER negative ones (P values=0.044, 0.008, 0.002 and 0.022, respectively). Moreover, expression of SNHG7 was higher in progesterone receptor (PR) positive samples compared with PR negative ones (P value=0.02). Finally, expressions of PRDM16-DT, SNHG7 and CDKN2A were higher in HER2/neu positive samples compared with HER2/neu negative ones (P values=0.017, 0.02 and 0.021, respectively). Taken together, our study demonstrates possible roles of these genes in breast cancer and warrants further functional studies.

The Prognostic Significance of P16 Immunohistochemical Expression Pattern in Women with Invasive Ductal Breast Carcinoma

Background

Breast cancer is the most common malignancy in women worldwide. The p16 protein is a cell cycle regulator and tumor suppressor implicated in several types of cancers. However, its relationship to breast cancer is still unknown. The present study aimed to assess the association of p16 protein expression with clinicopathological features in breast cancer.This study aimed to investigate the anti-cancer effects of different gum extracts on metabolic changes and their impact on gene expression in HT-29 cell.

Methods

The study enrolled 100 patients with invasive ductal carcinoma. The samples were collected before any adjuvant chemotherapy, and p16 protein expression was determined using immunohistochemistry. Clinicopathological features were obtained from the patient's medical records.

Results

Our findings demonstrated that p16 protein expression increased in estrogen receptor-positive tumor tissues (P< 0.01). However, no significant correlation was found between the p16 protein expression and the other clinicopathological features.

Conclusions

Our study demonstrated that p16 protein expression increased in ER-positive tumor tissue from patients with invasive ductal breast carcinoma. However, no correlation was found between the p16 protein expression and the other clinicopathological features.

CDK4/6 inhibitor resistance in estrogen receptor positive breast cancer, a 2023 perspective

CDK4/6 inhibitors have become game-changers in the treatment of estrogen receptor-positive (ER+) breast cancer, and in combination with endocrine therapy are the standard of care first-line treatment for ER+/HER2-negative advanced breast cancer. Although CDK4/6 inhibitors prolong survival for these patients, resistance is inevitable and there is currently no clear standard next-line treatment. There is an urgent unmet need to dissect the mechanisms which drive intrinsic and acquired resistance to CDK4/6 inhibitors and endocrine therapy to guide the subsequent therapeutic decisions. We will review the insights gained from preclinical studies and clinical cohorts into the diverse mechanisms of CDK4/6 inhibitor action and resistance, and highlight potential therapeutic strategies in the context of CDK4/6 inhibitor resistance.

Introducing Circulating Vasculature-Related Transcripts as Biomarkers in Coronary Artery Disease

BACKGROUND

Atherosclerotic plaque is considered the hallmark of atherosclerotic lesions in coronary atherosclerosis (CAS), the primary pathogenesis in coronary artery disease (CAD), which develops and progresses through a complex interplay between immune cells, vascular cells, and endothelial shear stresses. Early diagnosis of CAS is critical for avoiding plaque rupture and sudden death. Therefore, identifying new CAD biomarkers linked to vessel wall functions, such as RNA molecules with their distinct signature, is a promising development for these patients. With this rationale, the present study investigated the expression level of the vascular-related RNA transcripts (lncRNA ANRIL, miRNA-126-5p, CDK4, CDK6, TGF-β, E-cadherin, and TNF-α) implicated in the cellular vascular function, proliferation, and inflammatory processes.

METHODS

A case-control study design with a total of 180 subjects classified participants into two groups; CAD and control groups. The relative expression levels of the seven transcripts under study-selected using online bioinformatics tools and current literature-were assessed in the plasma of all study participants using RT-qPCR. Their predictive significance testing, scoring of disease prioritization, enrichment analysis, and the miRNA-mRNA regulatory network was investigated.

RESULTS

The relative expression levels of all seven of the circulating vascular-related transcripts under study were statistically significant between CAD patients and controls. Receiver operating characteristic (ROC) analysis results indicated the statistical significance of all the transcripts under study with CDK4 showing the highest area under the curve (AUC) equivalent to 0.91, followed by E-cadherin (0.90), miRNA-126-5p (0.83), ANRIL (0.82), TNF-α (0.63), TGF-β (0.62), and CDK6 (0.59), in descending order. A strong association was detected between most of the transcripts studied in CAD patients with a significant Spearman's correlation coefficient with a two-tailed significance of p < 0.001. Network analysis revealed a strong relationship between the five circulating vasculature transcripts studied and their target miRNAs and miR-126-5p, but not for ANRIL.

CONCLUSION

The seven circulating vascular-related RNA transcripts under study could serve as potential CAD biomarkers, reflecting the cellular vascular function, proliferation, and inflammatory processes in CAD patients. Therefore, blood transcriptome analysis opens new frontiers for the non-invasive diagnosis of CAD.

Epigenetic Abnormalities in Chondrosarcoma

In recent years, our understanding of the epigenetic mechanisms involved in tumor pathology has improved greatly. DNA and histone modifications, such as methylation, demethylation, acetylation, and deacetylation, can lead to the up-regulation of oncogenic genes, as well as the suppression of tumor suppressor genes. Gene expression can also be modified on a post-transcriptional level by microRNAs that contribute to carcinogenesis. The role of these modifications has been already described in many tumors, e.g., colorectal, breast, and prostate cancers. These mechanisms have also begun to be investigated in less common tumors, such as sarcomas. Chondrosarcoma (CS) is a rare type of tumor that belongs to sarcomas and is the second most common malignant bone tumor after osteosarcoma. Due to unknown pathogenesis and resistance to chemo- and radiotherapies of these tumors, there is a need to develop new potential therapies against CS. In this review, we summarize current knowledge on the influence of epigenetic alterations in the pathogenesis of CS by discussing potential candidates for future therapies. We also emphasize ongoing clinical trials that use drugs targeting epigenetic modifications in CS treatment.

Emerging approaches to CDK inhibitor development, a structural perspective

Aberrant activity of the cyclin-dependent kinase family is frequently noted in a number of diseases identifying them as potential targets for drug development. However, current CDK inhibitors lack specificity owing to the high sequence and structural conservation of the ATP binding cleft across family members, highlighting the necessity of finding novel modes of CDK inhibition. The wealth of structural information regarding CDK assemblies and inhibitor complexes derived from X-ray crystallographic studies has been recently complemented through the use of cryo-electron microscopy. These recent advances have provided insights into the functional roles and regulatory mechanisms of CDKs and their interaction partners. This review explores the conformational malleability of the CDK subunit, the importance of SLiM recognition sites in CDK complexes, the progress made in chemically induced CDK degradation and how these studies can contribute to CDK inhibitor design. Additionally, fragment-based drug discovery can be utilised to identify small molecules that bind to allosteric sites on the CDK surface employing interactions which mimic those of native protein-protein interactions. These recent structural advances in CDK inhibitor mechanisms and in chemical probes which do not occupy the orthosteric ATP binding site can provide important insights for targeted CDK therapies.

CDK4/6 Inhibitors in Pancreatobiliary Cancers: Opportunities and Challenges

Existing treatment strategies for pancreatobiliary malignancies are limited. Nowadays, surgery is the only path to cure these types of cancer, but only a small number of patients present with resectable tumors at the time of diagnosis. The notoriously poor prognosis, lack of diverse treatment options associated with pancreaticobiliary cancers, and their resistance to current therapies reflect the urge for the development of novel therapeutic targets. Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors have emerged as an attractive therapeutic strategy in a number of cancers since their approval for treatment in patients with ER+/HER- breast cancer in combination with antiestrogens. In this article, we discuss the therapeutic potential of CDK4/6 inhibitors in pancreatobiliary cancers, notably cholangiocarcinoma and pancreatic ductal adenocarcinoma.

Personalized matched targeted therapy in advanced pancreatic cancer: a pilot cohort analysis

Despite progress, 2-year pancreatic cancer survival remains dismal. We evaluated a biomarker-driven, combination/N-of-one strategy in 18 patients (advanced/metastatic pancreatic cancer) (from Molecular Tumor Board). Targeted agents administered/patient = 2.5 (median) (range, 1-4); first-line therapy (N = 5); second line, (N = 13). Comparing patients (high versus low degrees of matching) (matching score ≥50% versus <50%; reflecting number of alterations matched to targeted agents divided by number of pathogenic alterations), survival was significantly longer (hazard ratio [HR] 0.24 (95% confidence interval [CI], 0.078-0.76, P = 0.016); clinical benefit rates (CBR) (stable disease ≥6 months/partial/complete response) trended higher (45.5 vs 0.0%, P = 0.10); progression-free survival, HR, 95% CI, 0.36 (0.12-1.10) (p = 0.075). First versus ≥2nd-line therapy had higher CBRs (80.0 vs 7.7%, P = 0.008). No grade 3-4 toxicities occurred. The longest responder achieved partial remission (17.5 months) by co-targeting MEK and CDK4/6 alterations (chemotherapy-free). Therefore, genomically matched targeted agent combinations were active in these advanced pancreatic cancers. Larger prospective trials are warranted.

Obesity triggers tumoral senescence and renders poorly immunogenic malignancies amenable to senolysis

Obesity is a major risk factor for cancer. Conventional thought suggests that elevated adiposity predisposes to heightened inflammatory stress and potentiates tumor growth, yet underlying mechanisms remain ill-defined. Here, we show that tumors from patients with a body mass index >35 carry a high burden of senescent cells. In mouse syngeneic tumor models, we correlated a pronounced accretion of senescent cancer cells with poorly immunogenic tumors when mice were subjected to diet-induced obesity (DIO). Highly immunogenic tumors showed lesser senescence burden suggesting immune-mediated elimination of senescent cancer cells, likely targeted as a consequence of their senescence-associated secretory phenotype. Treatment with the senolytic BH3 mimetic small molecule inhibitor ABT-263 selectively stalled tumor growth in mice with DIO to rates comparable to regular diet-fed mice. Thus, consideration of body adiposity in the selection of cancer therapy may be a critical determinant for disease outcome in poorly immunogenic malignancies.

Decreased sensitivity of cyclin-dependent kinase 4/6 inhibitors, palbociclib and abemaciclib to canine lymphoma cells with high p16 protein expression and low retinoblastoma protein phosphorylation

Canine lymphoma/leukemia cell lines with p16 protein expressions: high (17-71 and GL-1) and low (CLBL-1, CLC, Nody-1, and UL-1) were treated in vitro with cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, palbociclib or abemaciclib. Cell proliferation decreased as a result, with higher IC₅₀ levels observed in the high p16 (17-71 and GL-1) and one low p16 (UL-1) cell lines compared with the low p16 cells (CLBL-1, CLC, and Nody-1). As expected, palbociclib and abemaciclib treatment reduced pRb phosphorylation in a dose-dependent manner, especially in cells with low p16. These results suggest that CDK4/6 inhibitors have potential as new chemotherapeutic agents for canine lymphoma and high p16 protein expression may be used as a biomarker for resistance to CDK4/6 inhibitor therapy.

Exploiting pivotal mechanisms behind the senescence-like cell cycle arrest in cancer

Senescence-like cell cycle arrest is a critical state of cancer initiation and progression. Senescence is an irreversible cell cycle arrest in response to stress induced by extrinsic and intrinsic stimuli, including oxidative/genotoxic stress, oncogenic activation, irradiation, mitochondrial malfunction, or chemotherapeutic drugs. Several signaling pathways are involved in senescence-like cell cycle arrest, which is primarily induced by the activation of p53/p21-dependent apoptotic pathways and suppressing p16INK4A/retinoblastoma protein (pRB)-dependent oncogenic pathways. p21 is necessary for proper cell cycle advancement, is involved in cell death, and mediates p53-dependent cell cycle arrest caused by DNA damage. pRB's role in tumor suppression is through modulation of the G1 checkpoint in the cell cycle, as it has the ability to block S-phase entry and cell growth. The aforementioned pathways are also highly interconnected with significant crosstalk, such as cyclin-dependent kinases (CDK)/cyclin complexes, and the dimerization partner, RB-like, E2F and multi-vulval class B (DREAM) complex. The primary regulators of transcription are p53 and pRB, which maintain the senescent state through negative control of the cell cycle and process of tumorigenesis. Because CDK inhibitors comprise negative regulators of cell cycle progress, they are fundamental parts of each route. Prolonged overexpression of any of these four fundamental elements (p16, p53, p21, and pRB) suffices to induce senescence, demonstrating how the regulatory DREAM complex causes senescence and how its malfunction results in cell cycle progression. The present chapter aims at revealing the pivotal mechanisms behind the senescence-like cell cycle arrest in cancer.

Facing the CDK4/6i resistance dilemma in patients with breast cancer, exploration of the resistance mechanism and possible reverse strategy: A narrative review

Breast cancer is one of the highest rates of malignancy of women, approximate 70% metastatic breast cancer are hormone receptor positive (HR+) and human epidermal growth factor receptor 2 negative (HER2-). Hormone therapy is the primary strategy of HR+/HER2- metastatic breast cancer. With the permission of cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i), progress free survival and overall survival were significantly licensed. However, inevitable outcome of CDK4/6i resistance has become the main reason that restricts the clinical benefit of patients. In recent years, the research on dealing with drug resistance has become a hot topic, a large number of molecular mechanisms have been focused, and a lot of experiments have been carried out at the preclinical level. This review summarizes the current knowledge of CDK4/6i resistance mechanism, systematically expounds the signaling pathways and targets leading to CDK4/6i resistance, analyzes different ways and mechanisms, and provides theoretical guidance for the clinical reversal of endocrine therapy resistance.

Non-canonical approaches to targeting hypoxic tumors

Hypoxia is a common characteristic in solid cancers. Hypoxia-inducible factors (HIFs) are involved in various aspects of cancer, such as angiogenesis, metastasis and therapy resistance. Targeting the HIF pathway has been regarded as a challenging but promising strategy in cancer treatment with recent FDA approval of a HIF2α-inhibitor. During the past several decades, numerous efforts have been made to understand how HIFs participate in cancer development and progression along with how HIF signaling can be modulated to achieve anti-cancer effect. In this chapter, we will provide an overview of the role of hypoxia and HIFs in cancer, summarize the oxygen-dependent and independent mechanisms of HIF-1α regulation, and discuss emerging approaches targeting hypoxia and HIF signaling which possess therapeutic potential in cancer. We will emphasize on two signaling pathways, involving cyclin-dependent kinases (CDKs) and heat shock protein 90 (HSP90), which contribute to HIF-1α (and HIF-2α) stabilization in an oxygen-independent manner. Through reviewing their participation in malignant progression and the potential targeting strategies, we discuss the non-canonical approaches to target HIF signaling in cancer therapy.

Resistance to CDK4/6 inhibition: Mechanisms and strategies to overcome a therapeutic problem in the treatment of hormone receptor-positive metastatic breast cancer

Selective CDK4/6 inhibitors, such as palbociclib, ribociclib, and abemaciclib, have been approved in combination with hormone therapy for the treatment of patients with HR+, HER2-negative advanced or metastatic breast cancer (mBC). Despite their promising activity, approximately 10 % of patients have de novo resistance, while the rest of them will develop acquired resistance after 24-28 months when used as first-line therapy and after a shorter period when used as second-line therapy. Various mechanisms of resistance to CDK4/6 inhibitors have been described, including cell cycle-related mechanisms, such as RB loss, p16 amplification, CDK6 or CDK4 amplification, and cyclin E-CDK2 amplification. Other bypass mechanisms involve the activation of FGFR or PI3K/AKT/mTOR pathways. Identifying the different mechanisms by which resistance to CDK4/6 inhibitors occurs may help to design new treatment strategies to improve patient outcomes. This review presents the currently available knowledge on the mechanisms of resistance to CDK4/6 inhibitors, explores possible treatment strategies that could overcome this therapeutic problem, and summarizes relevant recent clinical trials.

In vivo efficacy assessment of the CDK4/6 inhibitor palbociclib and the PLK1 inhibitor volasertib in human chordoma xenografts

Background

Management of advanced chordomas remains delicate considering their insensitivity to chemotherapy. Homozygous deletion of the regulatory gene CDKN2A has been described as the most frequent genetic alteration in chordomas and may be considered as a potential theranostic marker. Here, we evaluated the tumor efficacy of the CDK4/6 inhibitor palbociclib, as well as the PLK1 inhibitor volasertib, in three chordoma patient-derived xenograft (PDX) models to validate and identify novel therapeutic approaches.

Methods

From our chordoma xenograft panel, we selected three models, two of them harboring a homozygous deletion of CDKN2A/2B genes, and the last one a PBRM1 pathogenic variant (as control). For each model, we tested the palbociclib and volasertib drugs with pharmacodynamic studies together with RT-PCR and RNAseq analyses.

Results

For palbociclib, we observed a significant tumor response for one of two models harboring the deletion of CDKN2A/2B (p = 0.02), and no significant tumor response in the PBRM1-mutated PDX; for volasertib, we did not observe any response in the three tested models. RT-PCR and RNAseq analyses showed a correlation between cell cycle markers and responses to palbociclib; finally, RNAseq analyses showed a natural enrichment of the oxidative phosphorylation genes (OxPhos) in the palbociclib-resistant PDX (p = 0.02).

Conclusion

CDK4/6 inhibition appears as a promising strategy to manage advanced chordomas harboring a loss of CDKN2A/2B. However, further preclinical studies are strongly requested to confirm it and to understand acquired or de novo resistance to palbociclib, in the peculiar view of a targeting of the oxidative phosphorylation genes.

An evaluation of aging measures: from biomarkers to clocks

With the increasing number of aged population and growing burden of healthy aging demands, a rational standard for evaluation aging is in urgent need. The advancement of medical testing technology and the prospering of artificial intelligence make it possible to evaluate the biological status of aging from a more comprehensive view. In this review, we introduced common aging biomarkers and concluded several famous aging clocks. Aging biomarkers reflect changes in the organism at a molecular or cellular level over time while aging clocks tend to be more of a generalization of the overall state of the organism. We expect to construct a framework for aging evaluation measurement from both micro and macro perspectives. Especially, population-specific aging clocks and multi-omics aging clocks may better fit the demands to evaluate aging in a comprehensive and multidimensional manner and make a detailed classification to represent different aging rates at tissue/organ levels. This framework will promisingly provide a crucial basis for disease diagnosis and intervention assessment in geroscience.

Pancreatic Tumorigenesis: Precursors, Genetic Risk Factors and Screening

Pancreatic cancer (PC) is a highly malignant and aggressive tumor. Despite medical advancement, the silent nature of PC results in only 20% of all cases considered resectable at the time of diagnosis. It is projected to become the second leading cause in 2030. Most pancreatic cancer cases are diagnosed in the advanced stages. Such cases are typically unresectable and are associated with a 5-year survival of less than 10%. Although there is no guideline consensus regarding recommendations for screening for pancreatic cancer, early detection has been associated with better outcomes. In addition to continued utilization of imaging and conventional tumor markers, clinicians should be aware of novel testing modalities that may be effective for early detection of pancreatic cancer in individuals with high-risk factors. The pathogenesis of PC is not well understood; however, various modifiable and non-modifiable factors have been implicated in pancreatic oncogenesis. PC detection in the earlier stages is associated with better outcomes; nevertheless, most oncological societies do not recommend universal screening as it may result in a high false-positive rate. Therefore, targeted screening for high-risk individuals represents a reasonable option. In this review, we aimed to summarize the pathogenesis, genetic risk factors, high-risk population, and screening modalities for PC.

Define the Two Molecular Subtypes of Epithelioid Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a fatal disease of respiratory system. Despite the availability of invasive biomarkers with promising results, there are still significant diagnostic and therapeutic challenges in the treatment of MPM. One of three main mesothelioma cell types, epithelioid mesothelioma makes up approximately 70% of all mesothelioma cases. Different observational findings are under process, but the molecular heterogeneity and pathogenesis of epithelioid malignant pleural mesothelioma (eMPM) are still not well understood. Through molecular analysis, expression profiling data were used to determine the possibility and optimal number of eMPM molecular subtypes. Next, clinicopathological characteristics and different molecular pathways of each subtype were analyzed to prospect the clinical applications and advanced mechanisms of eMPM. In this study, we identified two distinct epithelioid malignant pleural mesothelioma subtypes with distinct gene expression patterns. Subtype I eMPMs were involved in steroid hormone biosynthesis, porphyrin and chlorophyll metabolism, and drug metabolism, while subtype II eMPMs were involved in rational metabolism, tyrosine metabolism, and chemical carcinogenesis pathways. Additionally, we identified potential subtype-specific therapeutic targets, including CCNE1, EPHA3, RNF43, ROS1, and RSPO2 for subtype I and CDKN2A and RET for subtype II. Considering the need for potent diagnostic and therapeutic biomarkers for eMPM, we are anticipating that our findings will help both in exploring underlying mechanisms in the development of eMPM and in designing targeted therapy for eMPM.

Epigenetic Control of Vascular Smooth Muscle Cell Function in Atherosclerosis: A Role for DNA Methylation

Atherosclerosis is a complex vascular inflammatory disease in which multiple cell types are involved, including vascular smooth muscle cells (VSMCs). In response to vascular injury and inflammatory stimuli, VSMCs undergo a "phenotypic switching" characterized by extracellular matrix secretion, loss of contractility, and abnormal proliferation and migration, which play a key role in the progression of atherosclerosis. DNA methylation modification is an important epigenetic mechanism that plays an important role in atherosclerosis. Studies investigating abnormal DNA methylation in patients with atherosclerosis have determined a specific DNA methylation profile, and proposed multiple pathways and genes involved in the etiopathogenesis of atherosclerosis. Recent studies have also revealed that DNA methylation modification controls VSMC function by regulating gene expression involved in atherosclerosis. In this review, we summarize the recent advances regarding the epigenetic control of VSMC function by DNA methylation in atherosclerosis and provide insights into the development of VSMC-centered therapeutic strategies.

Expression and therapeutic targeting of BMI1 in canine gliomas

The BMI1 proto-oncogene, polycomb ring finger protein (BMI1) is a key component of the epigenetic polycomb repressor complex 1, and has been associated with aggressive behavior and chemotherapeutic resistance in various malignances including human gliomas. Similar to humans, spontaneous canine gliomas carry a poor prognosis with limited therapeutic options. BMI1 expression and the effects of BMI1 inhibition have not been evaluated in canine gliomas. Here, we demonstrate that BMI1 is highly expressed in canine gliomas. Although increased BMI1 protein expression correlated with higher glioma grade in western blot assays, this correlation was not observed in a larger sample set using immunohistochemical analysis. The BMI1 inhibitor, PTC-209, suppressed BMI1 expression in established canine glioma cell lines and resulted in antiproliferative activity when used alone and in combination with chemotherapeutic agents. PTC-209 targeting of BMI1 activated the RB pathway through downregulation of total and phosphorylated RB, independent of INK4A/ARF signaling, likely through BMI1-inhibition mediated upregulation of p21. These data support the rationale for targeting of BMI1 signaling and the use of canine glioma as a translational therapeutic model for human disease. This article is protected by copyright. All rights reserved.

Selective Vulnerability of Senescent Glioblastoma Cells to BCL-XL Inhibition

Glioblastoma (GBM) is a rapidly fatal malignancy typically treated with radiation and temozolomide (TMZ), an alkylating chemotherapeutic. These cytotoxic therapies cause oxidative stress and DNA damage, yielding a senescent-like state of replicative arrest in surviving tumor cells. Unfortunately, recurrence is inevitable and may be driven by surviving tumor cells eventually escaping senescence. A growing number of so-called "senolytic" drugs have been recently identified that are defined by their ability to selectively eliminate senescent cells. A growing inventory of senolytic drugs is under consideration for several diseases associated with aging, inflammation, DNA damage, as well as cancer. Ablation of senescent tumor cells after radiation and chemotherapy could help mitigate recurrence by decreasing the burden of residual tumor cells at risk of recurrence. This strategy has not been previously explored for GBM. We evaluated a panel of 10 previously described senolytic drugs to determine whether any could exhibit selective activity against human GBM persisting after exposure to radiation or TMZ. Three of the 10 drugs have known activity against BCL-XL and preferentially induced apoptosis in radiated or TMZ-treated glioma. This senolytic activity was observed in 12 of 12 human GBM cell lines. Efficacy could not be replicated with BCL-2 inhibition or senolytic agents acting against other putative senolytic targets. Knockdown of BCL-XL decreased survival of radiated GBM cells, whereas knockdown of BCL-2 or BCL-W yielded no senolytic effect.

IMPLICATIONS

These findings imply that molecularly heterogeneous GBM lines share selective senescence-induced BCL-XL dependency increase the significance and translational relevance of the senolytic therapy for latent glioma.

Translation of Cellular Senescence to Novel Therapeutics: Insights From Alternative Tools and Models

Increasing chronological age is the greatest risk factor for human diseases. Cellular senescence (CS), which is characterized by permanent cell-cycle arrest, has recently emerged as a fundamental mechanism in developing aging-related pathologies. During the aging process, senescent cell accumulation results in senescence-associated secretory phenotype (SASP) which plays an essential role in tissue dysfunction. Although discovered very recently, senotherapeutic drugs have been already involved in clinical studies. This review gives a summary of the molecular mechanisms of CS and its role particularly in the development of cardiovascular diseases (CVD) as the leading cause of death. In addition, it addresses alternative research tools including the nonhuman and human models as well as computational techniques for the discovery of novel therapies. Finally, senotherapeutic approaches that are mainly classified as senolytics and senomorphics are discussed.

Advanced Molecular Characterisation in Relapsed and Refractory Paediatric Acute Leukaemia, the Key for Personalised Medicine

Relapsed and refractory (R/r) disease in paediatric acute leukaemia remains the first reason for treatment failure. Advances in molecular characterisation can ameliorate the identification of genetic biomarkers treatment strategies for this disease, especially in high-risk patients. The purpose of this study was to analyse a cohort of R/r children diagnosed with acute lymphoblastic (ALL) or myeloid (AML) leukaemia in order to offer them a targeted treatment if available. Advanced molecular characterisation of 26 patients diagnosed with R/r disease was performed using NGS, MLPA, and RT-qPCR. The clinical relevance of the identified alterations was discussed in a multidisciplinary molecular tumour board (MTB). A total of 18 (69.2%) patients were diagnosed with B-ALL, 4 (15.4%) with T-ALL, 3 (11.5%) with AML and 1 patient (3.8%) with a mixed-phenotype acute leukaemia (MPL). Most of the patients had relapsed disease (88%) at the time of sample collection. A total of 17 patients (65.4%) were found to be carriers of a druggable molecular alteration, 8 of whom (47%) received targeted therapy, 7 (87.5%) of them in addition to hematopoietic stem cell transplantation (HSCT). Treatment response and disease control were achieved in 4 patients (50%). In conclusion, advanced molecular characterisation and MTB can improve treatment and outcome in paediatric R/r acute leukaemias.

Functional and pathologic association of aminoacyl-tRNA synthetases with cancer

Although key tumorigenic and tumor-suppressive factors have been unveiled over the last several decades, cancer remains the most life-threatening disease. Multiomic analyses of patient samples and an in-depth understanding of tumorigenic processes have rapidly revealed unexpected pathologic associations of new cellular factors previously overlooked in cancer biology. In this regard, the newly discovered activities of human aminoacyl-tRNA synthases (ARSs) deserve attention not only for their pathological significance in tumorigenesis but also regarding diagnostic and therapeutic implications. ARSs are not only essential enzymes covalently linking substrate amino acids to cognate tRNAs for protein synthesis but also function as regulators of cellular processes by sensing different cellular conditions. With their catalytic role in protein synthesis and their regulatory role in homeostasis, functional alterations or dysregulation of ARSs might be pathologically associated with tumorigenesis. This review focuses on the potential implications of ARS genes and proteins in different aspects of cancer based on various bioinformatic analyses and experimental data. We also review their diverse activities involving extracellular secretion, protein–protein interactions, and amino acid sensing, which are related to cancers. The newly discovered cancer-related activities of ARSs are expected to provide new opportunities for detecting, preventing and curing cancers.

Enzymes called aminoacyl-tRNA synthetases (ARSs), which play a central role in all life, are becoming implicated in several aspects of cancer in ways that may lead to new approaches for prevention, detection and treatment. ARS enzymes catalyse the ligation of amino acids to transfer RNA molecules to allow amino acids to combine in the correct sequences to form proteins. Jung Min Han, Sunghoon Kim and colleagues at Yonsei University, Incheon, South Korea, review researches implicating ARS enzymes and the genes that code for them in a variety of cancers. The behavior of ARS enzymes and their genes are found to be altered in several types of cancer cells in ways that may either initiate or support the onset and development of the disease, through which they could be suggested as targets for novel anti-cancer drugs.

Cancer cell cycle dystopia: heterogeneity, plasticity, and therapy

The mammalian cell cycle has been extensively studied regarding cancer etiology, progression, and therapeutic intervention. The canonical cell cycle framework is supported by a plethora of data pointing to a relatively simple linear pathway in which mitogenic signals are integrated in a stepwise fashion to allow progression through G1/S with coordinate actions of cyclin-dependent kinases (CDK)4/6 and CDK2 on the RB tumor suppressor. Recent work on adaptive mechanisms and intrinsic heterogeneous dependencies indicates that G1/S control of the cell cycle is a variable signaling pathway rather than an invariant engine that drives cell division. These alterations can limit the effectiveness of pharmaceutical agents but provide new avenues for therapeutic interventions. These findings support a dystopian view of the cell cycle in cancer where the canonical utopian cell cycle is often not observed. However, recognizing the extent of cell cycle heterogeneity likely creates new opportunities for precision therapeutic approaches specifically targeting these states.