Ho Woon Fei

Mechanisms of sensitivity and resistance to CDK4/CDK6 inhibitors in hormone receptor-positive breast cancer treatment

Antonino Glaviano, Seth A. Wander, Richard D. Baird, Kenneth C.-H. Yap, Hiu Yan Lam, Masakazu Toi, Daniela Carbone, Birgit Geoerger, Violeta Serra, Robert H. Jones, Joanne Ngeow, Eneda Toska, Justin Stebbing, Karen Crasta, Richard S. Finn, Patrizia Diana, Karla Vuina, Robertus A.M. de Bruin, Uttam Surana, Aditya Bardia, Alan Prem Kumar

Cell cycle dysregulation is a hallmark of cancer that promotes eccessive cell division. Cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase 6 (CDK6) are key molecules in the G1-to-S phase cell cycle transition and are crucial for the onset, survival, and progression of breast cancer (BC). Small-molecule CDK4/CDK6 inhibitors (CDK4/6i) block phosphorylation of tumor suppressor Rb and thus restrain susceptible BC cells in G1 phase. Three CDK4/6i are approved for the first-line treatment of patients with advanced/metastatic hormone receptor-positive (HR⁺)/human epidermal growth factor receptor 2-negative (HER2^–) BC in combination with endocrine therapy (ET). Though this has improved the clinical outcomes for survival of BC patients, there is no established standard next-line treatment to tackle drug resistance. Recent studies suggest that CDK4/6i can modulate other distinct effects in both BC and breast stromal compartments, which may provide new insights into aspects of their clinical activity. This review describes the biochemistry of the CDK4/6-Rb-E2F pathway in HR⁺ BC, then discusses how CDK4/6i can trigger other effects in BC/breast stromal compartments, and finally outlines the mechanisms of CDK4/6i resistance that have emerged in recent preclinical studies and clinical cohorts, emphasizing the impact of these findings on novel therapeutic opportunities in BC.

Full article: https://www.sciencedirect.com/science/article/pii/S136876462400061X?via%3Dihub

Insights from multi-omic modeling of neurodegeneration in xeroderma pigmentosum using an induced pluripotent stem cell system
Cherif Badja, Sophie Momen, Gene Ching Chiek Koh, Soraya Boushaki, Theodoros I. Roumeliotis, Zuza Kozik, Ian Jones, Vicky Bousgouni, Jo~ao M.L. Dias, Marios G. Krokidis, Jamie Young, Hongwei Chen, Ming Yang, France Docquier, Yasin Memari, Lorea Valcarcel-Zimenez, Komal Gupta, Li Ren Kong, Heather Fawcett, Florian Robert, Salome Zhao, Andrea Degasperi, Yogesh Kumar, Helen Davies, Rebecca Harris, Christian Frezza, Chryssostomos Chatgilialoglu, Robert Sarkany, Alan Lehmann, Chris Bakal, Jyoti Choudhary, Hiva Fassihi, and Serena Nik-Zainal

Xeroderma pigmentosum(XP) is caused by defective nucleotide excision repair of DNA damage. This results in hypersensitivity to ultraviolet light and increased skin cancer risk, as sunlight-induced photoproducts remain unrepaired. However, many XP patients also display early-onset neurodegeneration, which leads to premature death. The mechanism of neurodegeneration is unknown. Here, we investigate XP neurodegeneration using pluripotent stemcellsderivedfromXPpatients andhealthy relatives, performingfunctional multi-omicsonsamples duringneuronaldifferentiation.We showsubstantially increasedlevels of 50,8-cyclopurineand8-oxopurine in XPneuronalDNAsecondary tomarked oxidative stress. Furthermore,we find that the endoplasmic reticulum stress response is upregulated and reversal of the mutant genotype is associatedwith phenotypic rescue. Critically, XP neurons exhibit inappropriate downregulation of the protein clearance ubiquitin-proteasome system (UPS). Chemical enhancement of UPS activity in XP neuronal models improves phenotypes, albeit inadequately. Although more work is required, this study presents insights with intervention potential.

Full article: https://www.cell.com/cell-reports/fulltext/S2211-1247(24)00571-0

Direct vagus nerve stimulation: A new tool to control allergic airway inflammation through α7 nicotinic acetylcholine receptor
Caroline Sévoz-Couche, Wupeng Liao, Hazel Y. C. Foo, Isabelle Bonne, Thong Beng Lu, Caris Tan Qi Hui, Wendy Yen Xian Peh, Shi-Cheng Yen, W. S. Fred Wong

Background and Purpose: Asthma is characterized by airway inflammation, mucus hypersecretion, and airway hyperresponsiveness. The use of nicotinic agents to mimic the cholinergic anti-inflammatory pathway (CAP) controls experimental asthma. Yet, the effects of vagus nerve stimulation (VNS)-induced CAP on allergic inflammation remain unknown.

Experimental Approach: BALB/c mice were sensitized and challenged with house dust mite (HDM) extract and treated with active VNS (5 Hz, 0.5 ms, 0.05–1 mA). Bronchoalveolar lavage (BAL) fluid was assessed for total and differential cell counts and cytokine levels. Lungs were examined by histopathology and electron microscopy.

Key Results: In the HDM mouse asthma model, VNS at intensities equal to or above 0.1 mA (VNS 0.1) but not sham VNS reduced BAL fluid differential cell counts and alveolar macrophages expressing α7 nicotinic receptors (α7nAChR), goblet cell hyperplasia, and collagen deposition. Besides, VNS 0.1 also abated HDM-induced elevation of type 2 cytokines IL-4 and IL-5 and was found to block the phosphorylation of transcription factor STAT6 and expression level of IRF4 in total lung lysates. Finally, VNS 0.1 abrogated methacholine-induced hyperresponsiveness in asthma mice. Prior administration of α-bungarotoxin, a specific inhibitor of α7nAChR, but not propranolol, a specific inhibitor of β2-adrenoceptors, abolished the therapeutic effects of
VNS 0.1.

Conclusion and Implications: Our data revealed the protective effects of VNS on various clinical features in allergic airway inflammation model. VNS, a clinically approved therapy for depression and epilepsy, appears to be a promising new strategy for controlling allergic asthma.

A glycolytic metabolite bypasses ‘‘two-hit’’ tumor suppression by BRCA2
Li Ren Kong, Komal Gupta, Andy Jialun Wu, David Perera, Roland lvanyi-Nagy, Syed Moiz Ahmed, Tuan Zea Tan, Shawn Lu-Wen Tan, Alessandra Fuddin, Elayanambi Sundaramoorthy, Grace Shiqing Goh, Regina Tong Xin Wong, Ana S.H. Costa, Callum Oddy, Hannan Wong, C. Pawan K. Patro, Yun Suen Kho,
Xiao Zi Huang, Joan Choo, Mona Shehata, Soo Chin Lee, Boon Cher Goh, Christian Frezza, Jason J. Pitt, and Ashok R. Venkitaraman

Knudson’s “two-hit” paradigm posits that carcinogenesis requires inactivation of both copies of an autosomal tumor suppressor gene. Here, we report that the glycolytic metabolite methylglyoxal (MGO) transiently bypasses Knudson’s paradigm by inactivating the breast cancer suppressor protein BRCA2 to elicit a cancer-associated, mutational single-base substitution (SBS) signature in nonmalignant mammary cells or patient-derived organoids. Germline monoallelic BRCA2 mutations predispose to these changes. An analogous SBS signature, again without biallelic BRCA2 inactivation, accompanies MGO accumulation and DNA dam­ age in Kras-driven, Brca2-mutant murine pancreatic cancers and human breast cancers. MGO triggers BRCA2 proteolysis, temporarily disabling BRCA2’s tumor suppressive functions in DNA repair and replication, causing functional haploinsufficiency. Intermittent MGO exposure incites episodic SBS mutations without permanent BRCA2 inactivation. Thus, a metabolic mechanism wherein MGO-induced BRCA2 haploinsufficiency transiently bypasses Knudson’s two-hit requirement could link glycolysis activation by onco­ genes, metabolic disorders, or dietary challenges to mutational signatures implicated in cancer evolution.

Link to full article: https://pubmed.ncbi.nlm.nih.gov/38417710/