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JACS Au May 2024Cyclin-dependent kinases (CDKs), particularly CDK4 and CDK2, are crucial for cell cycle progression from the Gap 1 (G1) to the Synthesis (S) phase by phosphorylating...
Cyclin-dependent kinases (CDKs), particularly CDK4 and CDK2, are crucial for cell cycle progression from the Gap 1 (G1) to the Synthesis (S) phase by phosphorylating targets such as the Retinoblastoma Protein (Rb). CDK4, paired with cyclin-D, operates in the long G1 phase, while CDK2 with cyclin-E, manages the brief G1-to-S transition, enabling DNA replication. Aberrant CDK signaling leads to uncontrolled cell proliferation, which is a hallmark of cancer. Exactly how they accomplish their catalytic phosphorylation actions with distinct efficiencies poses the fundamental, albeit overlooked question. Here we combined available experimental data and modeling of the active complexes to establish their conformational functional landscapes to explain how the two cyclin/CDK complexes differentially populate their catalytically competent states for cell cycle progression. Our premise is that CDK could be more important for cell cycle progression than the cyclin-CDK biochemical binding specificity and that efficiency is likely the prime determinant of cell cycle progression. We observe that CDK4 is more dynamic than CDK2 in the ATP binding site, the regulatory spine, and the interaction with its cyclin partner. The N-terminus of cyclin-D acts as an allosteric regulator of the activation loop and the ATP-binding site in CDK4. Integrated with a suite of experimental data, we suggest that the CDK4 complex is less capable of remaining in the active catalytically competent conformation, and may have a lower catalytic efficiency than CDK2, befitting their cell cycle time scales, and point to critical residues and motifs that drive their differences. Our mechanistic landscape may apply broadly to kinases, and we propose two drug design strategies: (i) allosteric Inhibition by conformational stabilization for targeting allosteric CDK4 regulation by cyclin-D, and (ii) dynamic entropy-optimized targeting which leverages the dynamic, entropic aspects of CDK4 to optimize drug binding efficacy.
PubMed: 38818077
DOI: 10.1021/jacsau.4c00138 -
Journal of Pediatric Ophthalmology and... May 2024
PubMed: 38815108
DOI: 10.3928/01913913-20240508-09 -
Journal of Pediatric Ophthalmology and... May 2024
PubMed: 38815105
DOI: 10.3928/01913913-20240508-07 -
Journal of Pediatric Ophthalmology and... May 2024
PubMed: 38815101
DOI: 10.3928/01913913-20240425-01 -
TouchREVIEWS in Endocrinology Apr 2024Previous studies have suggested that corticotroph tumours are associated with the overexpression of cyclin E and that the inactivation of cyclin-dependent kinases, which...
Previous studies have suggested that corticotroph tumours are associated with the overexpression of cyclin E and that the inactivation of cyclin-dependent kinases, which activate cyclin E, may have antisecretory and antiproliferative effects. Seliciclib, also known as R-roscovitine, is a pituitary-targeting agent shown to inhibit the growth of corticotroph tumour cells via cyclin E and retinoblastoma protein-mediated pathways. A recent study investigated the role of seliciclib in regulating biochemical parameters in a small number of patients with Cushing's disease, providing preliminary data on its possible therapeutic effectiveness in treating this disorder.
PubMed: 38812663
DOI: 10.17925/EE.2023.20.1.4 -
World Journal of Clinical Cases May 2024Neuroendocrine prostate cancer (NEPC) shows an aggressive behavior compared to prostate cancer (PCa), also known as prostate adenocarcinoma. Scanty foci in PCa can...
Neuroendocrine prostate cancer (NEPC) shows an aggressive behavior compared to prostate cancer (PCa), also known as prostate adenocarcinoma. Scanty foci in PCa can harbor genetic alternation that can arise in a heterogeneity of prostate cancer. NEPC may arise or develop following androgen deprivation therapy (ADT). NEPC that arise following ADT has the nomenclature "treatment-emerging/induced NEPC (t-NEPC)". t-NEPC would be anticipated in castration resistant prostate cancer (CRPC) and metastatic PCa. t-NEPC is characterized by low or absent androgen receptor (AR) expression, independence of AR signaling, and gain of neuroendocrine phenotype. t-NEPC is an aggressive metastatic tumor, develops from PCa in response to drug induced ADT, and shows very short response to conventional therapy. t-NEPC occurs in 10%-17% of patients with CRPC. NEPC is rare and is accounting for less than 2% of all PCa. The molecular mechanisms underlying the trans-differentiation from CRPC to t-NEPC are not fully elucidated. Sphingosine kinase 1 plays a significant role in t-NEPC development. Although neuroendocrine markers: Synaptophysin, chromogranin A, and insulinoma associated protein 1 () are expressed in t-NEPC, they are non-specific for diagnosis, prognosis, and follow-up of therapy. t-NEPC shows enriched genomic alteration in tumor protein P53 () and retinoblastoma 1 (). There are evidences suggest that t-NEPC might develop through epigenetic evolution. There are genomic, epigenetic, and transcriptional alterations that are reported to be involved in development of t-NEPC. Knock-outs of and were found to contribute in development of t-NEPC. PCa is resistant to immunotherapy, and at present there are running trials to approach immunotherapy for PCa, CRPC, and t-NEPC.
PubMed: 38808339
DOI: 10.12998/wjcc.v12.i13.2143 -
Indian Journal of Ophthalmology Jun 2024Retinoblastoma is the most common pediatric ocular malignancy. It is triggered by a biallelic mutation in the RB1 gene or MYCN oncogene amplification. Retinoblastomas... (Review)
Review
Retinoblastoma is the most common pediatric ocular malignancy. It is triggered by a biallelic mutation in the RB1 gene or MYCN oncogene amplification. Retinoblastomas can be unilateral (60%-70%) or bilateral (30%-40%); bilateral tumors are always heritable and present at an earlier age as compared to unilateral ones (18-24 months vs. 36 months in India). High prevalence rates, delayed presentation, and inaccessibility to healthcare lead to worse outcomes in developing countries. The past few decades have seen a paradigm change in the treatment of retinoblastomas, shifting from enucleation and external beam radiotherapy to less aggressive modalities for eye salvage. Multimodality treatment is now the standard of care and includes intraarterial or intravenous chemotherapy along with focal consolidation therapies such as transpupillary thermotherapy, cryotherapy, and laser photocoagulation. Intravitreal and intracameral chemotherapy can help in controlling intraocular seeds. Advanced extraocular or metastatic tumors still have a poor prognosis. Genetic testing, counseling, and screening of at-risk family members must be incorporated as essential parts of management. A better understanding of the genetics and molecular basis of retinoblastoma has opened up the path for potential targeted therapy in the future. Novel recent advances such as liquid biopsy, prenatal diagnosis, prognostic biomarkers, tylectomy, and chemoplaque point to promising future directions.
Topics: Humans; Retinoblastoma; Retinal Neoplasms; Global Health; Combined Modality Therapy
PubMed: 38804799
DOI: 10.4103/IJO.IJO_2414_23 -
The Lancet Regional Health. Europe Apr 2024Childhood cancer predisposition (ChiCaP) syndromes are increasingly recognized as contributing factors to childhood cancer development. Yet, due to variable availability...
BACKGROUND
Childhood cancer predisposition (ChiCaP) syndromes are increasingly recognized as contributing factors to childhood cancer development. Yet, due to variable availability of germline testing, many children with ChiCaP might go undetected today. We report results from the nationwide and prospective ChiCaP study that investigated diagnostic yield and clinical impact of integrating germline whole-genome sequencing (gWGS) with tumor sequencing and systematic phenotyping in children with solid tumors.
METHODS
gWGS was performed in 309 children at diagnosis of CNS (n = 123, 40%) or extracranial (n = 186, 60%) solid tumors and analyzed for disease-causing variants in 189 known cancer predisposing genes. Tumor sequencing data were available for 74% (227/309) of patients. In addition, a standardized clinical assessment for underlying predisposition was performed in 95% (293/309) of patients.
FINDINGS
The prevalence of ChiCaP diagnoses was 11% (35/309), of which 69% (24/35) were unknown at inclusion (diagnostic yield 8%, 24/298). A second-hit and/or relevant mutational signature was observed in 19/21 (90%) tumors with informative data. ChiCaP diagnoses were more prevalent among patients with retinoblastomas (50%, 6/12) and high-grade astrocytomas (37%, 6/16), and in those with non-cancer related features (23%, 20/88), and ≥2 positive ChiCaP criteria (28%, 22/79). ChiCaP diagnoses were autosomal dominant in 80% (28/35) of patients, yet confirmed in 64% (18/28). The 35 ChiCaP findings resulted in tailored surveillance (86%, 30/35) and treatment recommendations (31%, 11/35).
INTERPRETATION
Overall, our results demonstrate that systematic phenotyping, combined with genomics-based diagnostics of ChiCaP in children with solid tumors is feasible in large-scale clinical practice and critically guides personalized care in a sizable proportion of patients.
FUNDING
The study was supported by the Swedish Childhood Cancer Fund and the Ministry of Health and Social Affairs.
PubMed: 38803632
DOI: 10.1016/j.lanepe.2024.100881 -
BioRxiv : the Preprint Server For... May 2024Ovarian cancer remains a major health threat with limited treatment options available. It is characterized by immunosuppressive tumor microenvironment (TME) maintained...
UNLABELLED
Ovarian cancer remains a major health threat with limited treatment options available. It is characterized by immunosuppressive tumor microenvironment (TME) maintained by tumor- associated macrophages (TAMs) hindering anti-tumor responses and immunotherapy efficacy. Here we show that targeting retinoblastoma protein (Rb) by disruption of its LxCxE cleft pocket, causes cell death in TAMs by induction of ER stress, p53 and mitochondria-related cell death pathways. A reduction of pro-tumor Rb M2-type macrophages from TME in vivo enhanced T cell infiltration and inhibited cancer progression. We demonstrate an increased Rb expression in TAMs in women with ovarian cancer is associated with poorer prognosis. Ex vivo, we show analogous cell death induction by therapeutic Rb targeting in TAMs in post-surgery ascites from ovarian cancer patients. Overall, our data elucidates therapeutic targeting of the Rb LxCxE cleft pocket as a novel promising approach for ovarian cancer treatment through depletion of TAMs and re-shaping TME immune landscape.
STATEMENT OF SIGNIFICANCE
Currently, targeting immunosuppressive myeloid cells in ovarian cancer microenvironment is the first priority need to enable successful immunotherapy, but no effective solutions are clinically available. We show that targeting LxCxE cleft pocket of Retinoblastoma protein unexpectedly induces preferential cell death in M2 tumor-associated macrophages. Depletion of immunosuppressive M2 tumor-associated macrophages reshapes tumor microenvironment, enhances anti-tumor T cell responses, and inhibits ovarian cancer. Thus, we identify a novel paradoxical function of Retinoblastoma protein in regulating macrophage viability as well as a promising target to enhance immunotherapy efficacy in ovarian cancer.
PubMed: 38798466
DOI: 10.1101/2024.05.10.593562 -
Discovery Medicine May 2024SGI-1027 is a recognized inhibitor of DNA methyltransferase 1 (DNMT1), and earlier investigations have indicated an inverse correlation between dysregulated DNMT1...
BACKGROUND
SGI-1027 is a recognized inhibitor of DNA methyltransferase 1 (DNMT1), and earlier investigations have indicated an inverse correlation between dysregulated DNMT1 expression in gastric cancer (GC) and retinoblastoma 1 () gene expression. Despite this knowledge, the precise mechanisms underlying the action of SGI-1027 in GC cells remain inadequately comprehended. The primary objective of this study is to elucidate the impact of SGI-1027 on the behavior of GC cells, encompassing aspects such as growth and metastatic potential, by intervening in DNMT1, thereby influencing the regulation of gene expression.
METHOD
The acquisition of the normal gastric mucosal cell line GES-1 and the human gastric cancer cell line MKN45 was followed by employing Western blot (WB) and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) techniques to evaluate the expression levels of RB1 and DNMT1 in these two cell lines. Subsequently, the MKN45 cell line was cultured in medium containing varying concentrations of SGI-1027, and the impact of SGI-1027 on the regulation of and DNMT1 in GC cells was reassessed using WB and qRT-PCR techniques. To scrutinize the effect of SGI-1027 on GC cells, we utilized the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide (MTT) assay to determine cell proliferation and performed Transwell experiments to assess cell migration and invasion capabilities. Throughout this process, we also employed WB to assess the levels of cell cycle-associated proteins (Cyclin D1, Cyclin E1, and Cyclin B1) and proteins related to apoptosis (BCL-2 associated protein X apoptosis regulator (BAX) and B-cell lymphoma 2 apoptosis regulator (BCL-2)). Furthermore, we injected the MKN45 cell line and MKN45 cell line cultured with the optimal concentration of SGI-1027 for 5 days and 10 days into mice subcutaneously and through the tail vein, dividing them into the Model group, Model+SGI-1027 5d group, and Model+SGI-1027 10d group. We monitored changes in tumor size and volume in mice, and tumor tissues as well as lung tissues were collected for hematoxylin and eosin (HE) staining. Finally, DNMT1 expression levels in GC tissues were detected using both WB and immunohistochemistry (IHC) techniques. Additionally, RB1 expression levels in GC tissues were assessed using WB.
RESULT
In contrast to GES-1 cells, MKN45 cells displayed a distinctive profile characterized by increased DNMT1 expression and decreased RB1 expression ( < 0.05). However, upon the introduction of SGI-1027, a notable decrease in DNMT1 levels within GC cells was observed, concomitant with an elevation in gene expression, with 25 μmol/L SGI-1027 identified as the optimal concentration ( < 0.05). Functional assays demonstrated that SGI-1027-treated GC cells exhibited pronounced features of inhibited proliferation, migration, and invasion when compared to untreated MKN45 cells ( < 0.05). Moreover, in SGI-1027-treated GC cells, the levels of Cyclin D1, Cyclin E1, Cyclin B1, and BCL-2 were significantly reduced, while the expression level of BAX increased ( < 0.05). Notably, the most pronounced impact was observed at 25 μmol/L SGI-1027, further underscoring its regulatory effects on tumor cell behavior ( < 0.05). In animal experiments, the Model group exhibited a substantial increase in tumor volume, with HE staining results indicating extensive necrosis in most gastric tissues and noticeable signs of lung metastasis, accompanied by increased DNMT1 expression and decreased gene expression. In contrast, the SGI-1027 group displayed a reduction in gastric tumor volume, decreased necrosis, and reduced lung tumor metastasis ( < 0.05). Additionally, the expression of DNMT1 was significantly reduced in SGI-1027-treated GC cells, while RB1 expression increased ( < 0.05), further confirming the inhibitory effects of SGI-1027 on tumor growth and metastasis.
CONCLUSIONS
SGI-1027 effectively hinders the proliferation and dissemination of GC cells by downregulating DNMT1 and promoting the expression of .
Topics: Humans; Stomach Neoplasms; DNA (Cytosine-5-)-Methyltransferase 1; Cell Line, Tumor; Animals; Gene Expression Regulation, Neoplastic; Cell Proliferation; Retinoblastoma Binding Proteins; Mice; Neoplasm Metastasis; Cell Movement; Mice, Nude; Ubiquitin-Protein Ligases; Retinoblastoma Protein; Mice, Inbred BALB C; Repressor Proteins
PubMed: 38798252
DOI: 10.24976/Discov.Med.202436184.86