bims-pimaco 2024-04-21 papers

bims-pimaco

Biomed News

on PI3K and MAPK signalling in colorectal cancer

Issue of 2024–04–21
ten papers selected by
Lucas B. Zeiger

Amino acid transporter SLC7A5 regulates cell proliferation and secretary cell differentiation and distribution in the mouse intestine.
A p85 isoform switch enhances PI3K activation on endosomes by a MAP4- and PI3P-dependent mechanism.
Arachidonic acid released by PIK3CA mutant tumor cells triggers malignant transformation of colonic epithelium by inducing chromatin remodeling.
Combinatorial strategies to target RAS-driven cancers.
The SOS1 Inhibitor MRTX0902 Blocks KRAS Activation and Demonstrates Antitumor Activity in Cancers Dependent on KRAS Nucleotide Loading.
Targeting KRAS in cancer.
Crystal structure of NRAS Q61K with a ligand-induced pocket near switch II.
Monoallelic KRAS (G13C) mutation triggers dysregulated expansion in induced pluripotent stem cell-derived hematopoietic progenitor cells.
Membrane to cortex attachment determines different mechanical phenotypes in LGR5+ and LGR5- colorectal cancer cells.
Tissue-specific genetic variation suggests distinct molecular pathways between body shape phenotypes and colorectal cancer.

Int J Biol Sci. 2024 ;20(6): 2187-2201

Amino acid transporter SLC7A5 regulates cell proliferation and secretary cell differentiation and distribution in the mouse intestine.

Lingyu Bao, Liezhen Fu, Yijun Su, Zuojia Chen, Zhaoyi Peng, Lulu Sun, Frank J Gonzalez, Chuan Wu, Hongen Zhang, Bingyin Shi, Yun-Bo Shi.

  The intestine is critical for not only processing nutrients but also protecting the organism from the environment. These functions are mainly carried out by the epithelium, which is constantly being self-renewed. Many genes and pathways can influence intestinal epithelial cell proliferation. Among them is mTORC1, whose activation increases cell proliferation. Here, we report the first intestinal epithelial cell (IEC)-specific knockout (ΔIEC) of an amino acid transporter capable of activating mTORC1. We show that the transporter, SLC7A5, is highly expressed in mouse intestinal crypt and Slc7a5ΔIEC reduces mTORC1 signaling. Surprisingly, adult Slc7a5ΔIEC intestinal crypts have increased cell proliferation but reduced mature Paneth cells. Goblet cells, the other major secretory cell type in the small intestine, are increased in the crypts but reduced in the villi. Analyses with scRNA-seq and electron microscopy have revealed dedifferentiation of Paneth cells in Slc7a5ΔIEC mice, leading to markedly reduced secretory granules with little effect on Paneth cell number. Thus, SLC7A5 likely regulates secretory cell differentiation to affect stem cell niche and indirectly regulate cell proliferation.

Keywords:  amino acid transporter; intestine; mTORC1 signaling pathway; organ homeostasis; stem cell

DOI:  https://doi.org/10.7150/ijbs.94297
Cell Rep. 2024 Apr 16. pii: S2211-1247(24)00447-9. [Epub ahead of print]43(5): 114119

A p85 isoform switch enhances PI3K activation on endosomes by a MAP4- and PI3P-dependent mechanism.

Narendra Thapa, Mo Chen, Vincent L Cryns, Richard Anderson.

  Phosphatidylinositol 3-kinase α (PI3Kα) is a heterodimer of p110α catalytic and p85 adaptor subunits that is activated by agonist-stimulated receptor tyrosine kinases. Although p85α recruits p110α to activated receptors on membranes, p85α loss, which occurs commonly in cancer, paradoxically promotes agonist-stimulated PI3K/Akt signaling. p110α localizes to microtubules via microtubule-associated protein 4 (MAP4), facilitating its interaction with activated receptor kinases on endosomes to initiate PI3K/Akt signaling. Here, we demonstrate that in response to agonist stimulation and p85α knockdown, the residual p110α, coupled predominantly to p85β, exhibits enhanced recruitment with receptor tyrosine kinases to endosomes. Moreover, the p110α C2 domain binds PI3-phosphate, and this interaction is also required to recruit p110α to endosomes and for PI3K/Akt signaling. Stable knockdown of p85α, which mimics the reduced p85α levels observed in cancer, enhances cell growth and tumorsphere formation, and these effects are abrogated by MAP4 or p85β knockdown, underscoring their role in the tumor-promoting activity of p85α loss.

Keywords:  Akt; CP: Cell biology; MAP4; PI3K; PI3P; endosomes; p110α; p85α; p85β

DOI:  https://doi.org/10.1016/j.celrep.2024.114119
Cell Rep Med. 2024 Apr 05. pii: S2666-3791(24)00179-4. [Epub ahead of print] 101510

Arachidonic acid released by PIK3CA mutant tumor cells triggers malignant transformation of colonic epithelium by inducing chromatin remodeling.

Baoyu He, Qingli Bie, Rou Zhao, Yugang Yan, Guanjun Dong, Baogui Zhang, Sen Wang, Wenrong Xu, Dongxing Tian, Yujun Hao, Yanhua Zhang, Mingsheng Zhao, Huabao Xiong, Bin Zhang.

  Key gene mutations are essential for colorectal cancer (CRC) development; however, how the mutated tumor cells impact the surrounding normal cells to promote tumor progression has not been well defined. Here, we report that PIK3CA mutant tumor cells transmit oncogenic signals and result in malignant transformation of intestinal epithelial cells (IECs) via paracrine exosomal arachidonic acid (AA)-induced H3K4 trimethylation. Mechanistically, PIK3CA mutations sustain SGK3-FBW7-mediated stability of the cPLA2 protein, leading to the synthetic increase in AA, which is transported through exosome and accumulated in IECs. Transferred AA directly binds Menin and strengthens the interactions of Menin and MLL1/2 methyltransferase. Finally, the combination of VTP50469, an inhibitor of the Menin-MLL interaction, and alpelisib synergistically represses PDX tumors harboring PIK3CA mutations. Together, these findings unveil the metabolic link between PIK3CA mutant tumor cells and the IECs, highlighting AA as the potential target for the treatment of patients with CRC harboring PIK3CA mutations.

Keywords:  H3K4 trimethylation; Menin; PIK3CA mutations; VTP50469; arachidonic acid; cPLA2; exosome; intestinal epithelial cells; malignant transformation

DOI:  https://doi.org/10.1016/j.xcrm.2024.101510
Nat Rev Cancer. 2024 Apr 16.

Combinatorial strategies to target RAS-driven cancers.

Naiara Perurena, Lisa Situ, Karen Cichowski.

Although RAS was formerly considered undruggable, various agents that inhibit RAS or specific RAS oncoproteins have now been developed. Indeed, the importance of directly targeting RAS has recently been illustrated by the clinical success of mutant-selective KRAS inhibitors. Nevertheless, responses to these agents are typically incomplete and restricted to a subset of patients, highlighting the need to develop more effective treatments, which will likely require a combinatorial approach. Vertical strategies that target multiple nodes within the RAS pathway to achieve deeper suppression are being investigated and have precedence in other contexts. However, alternative strategies that co-target RAS and other therapeutic vulnerabilities have been identified, which may mitigate the requirement for profound pathway suppression. Regardless, the efficacy of any given approach will likely be dictated by genetic, epigenetic and tumour-specific variables. Here we discuss various combinatorial strategies to treat KRAS-driven cancers, highlighting mechanistic concepts that may extend to tumours harbouring other RAS mutations. Although many promising combinations have been identified, clinical responses will ultimately depend on whether a therapeutic window can be achieved and our ability to prospectively select responsive patients. Therefore, we must continue to develop and understand biologically diverse strategies to maximize our likelihood of success.

DOI: https://doi.org/10.1038/s41568-024-00679-6
Mol Cancer Ther. 2024 Apr 19.

The SOS1 Inhibitor MRTX0902 Blocks KRAS Activation and Demonstrates Antitumor Activity in Cancers Dependent on KRAS Nucleotide Loading.

Niranjan Sudhakar, Larry Yan, Fadia Qiryaqos, Lars D Engstrom, Jade Laguer, Andrew Calinisan, Allan Hebbert, Laura Waters, Krystal Moya, Vickie Bowcut, Laura Vegar, John M Ketcham, Anthony Ivetac, Christopher R Smith, J David Lawson, Lisa Rahbaek, Jeffrey Clarine, Natalie Nguyen, Barbara Saechao, Cody Parker, Adam J Elliott, Darin Vanderpool, Leo He, Laura D Hover, Julio Fernandez-Banet, Silvia Coma, Jonathan A Pachter, Jill Hallin, Matthew A Marx, David M Briere, James G Christensen, Peter Olson, Jacob Haling, Shilpi Khare.

KRAS is the most frequently mutated oncogene in human cancer and facilitates uncontrolled growth through hyperactivation of the RTK/MAPK pathway. The Son of Sevenless homolog 1 (SOS1) protein functions as a guanine nucleotide exchange factor (GEF) for the RAS subfamily of small GTPases and represents a druggable target in the pathway. Using a structure-based drug discovery approach, MRTX0902 was identified as a selective and potent SOS1 inhibitor that disrupts the KRAS:SOS1 protein-protein interaction to prevent SOS1-mediated nucleotide exchange on KRAS and translates into an anti-proliferative effect in cancer cell lines with genetic alterations of the KRAS-MAPK pathway. MRTX0902 augmented the antitumor activity of the KRAS G12C inhibitor adagrasib when dosed in combination in eight out of twelve KRAS G12C-mutant human non-small cell lung cancer (NSCLC) and colorectal cancer (CRC) xenograft models. Pharmacogenomic profiling in preclinical models identified cell cycle genes and the SOS2 homolog as genetic co-dependencies and implicated tumor suppressor genes (NF1, PTEN) in resistance following combination treatment. Lastly, combined vertical inhibition of RTK/MAPK pathway signaling by MRTX0902 with inhibitors of EGFR or RAF/MEK led to greater downregulation of pathway signaling and improved antitumor responses in KRAS-MAPK pathway-mutant models. These studies demonstrate the potential clinical application of dual inhibition of SOS1 and KRAS G12C and additional SOS1 combination strategies that will aide in the understanding of SOS1 and RTK/MAPK biology in targeted cancer therapy.

DOI: https://doi.org/10.1158/1535-7163.MCT-23-0870
Nat Med. 2024 Apr;30(4): 969-983

Targeting KRAS in cancer.

Anupriya Singhal, Bob T Li, Eileen M O'Reilly.

RAS family variants-most of which involve KRAS-are the most commonly occurring hotspot mutations in human cancers and are associated with a poor prognosis. For almost four decades, KRAS has been considered undruggable, in part due to its structure, which lacks small-molecule binding sites. But recent developments in bioengineering, organic chemistry and related fields have provided the infrastructure to make direct KRAS targeting possible. The first successes occurred with allele-specific targeting of KRAS p.Gly12Cys (G12C) in non-small cell lung cancer, resulting in regulatory approval of two agents-sotorasib and adagrasib. Inhibitors targeting other variants beyond G12C have shown preliminary antitumor activity in highly refractory malignancies such as pancreatic cancer. Herein, we outline RAS pathobiology with a focus on KRAS, illustrate therapeutic approaches across a variety of malignancies, including emphasis on the 'on' and 'off' switch allele-specific and 'pan' RAS inhibitors, and review immunotherapeutic and other key combination RAS targeting strategies. We summarize mechanistic understanding of de novo and acquired resistance, review combination approaches, emerging technologies and drug development paradigms and outline a blueprint for the future of KRAS therapeutics with anticipated profound clinical impact.

DOI: https://doi.org/10.1038/s41591-024-02903-0
Eur J Cell Biol. 2024 Apr 15. pii: S0171-9335(24)00031-1. [Epub ahead of print]103(2): 151414

Crystal structure of NRAS Q61K with a ligand-induced pocket near switch II.

Teklab Gebregiworgis, Jonathan Yui-Lai Chan, Douglas A Kuntz, Gilbert G Privé, Christopher B Marshall, Mitsuhiko Ikura.

  The RAS isoforms (KRAS, HRAS and NRAS) have distinct cancer type-specific profiles. NRAS mutations are the second most prevalent RAS mutations in skin and hematological malignancies. Although RAS proteins were considered undruggable for decades, isoform and mutation-specific investigations have produced successful RAS inhibitors that are either specific to certain mutants, isoforms (pan-KRAS) or target all RAS proteins (pan-RAS). While extensive structural and biochemical investigations have focused mainly on K- and H-RAS mutations, NRAS mutations have received less attention, and the most prevalent NRAS mutations in human cancers, Q61K and Q61R, are rare in K- and H-RAS. This manuscript presents a crystal structure of the NRAS Q61K mutant in the GTP-bound form. Our structure reveals a previously unseen pocket near switch II induced by the binding of a ligand to the active form of the protein. This observation reveals a binding site that can potentially be exploited for development of inhibitors against mutant NRAS. Furthermore, the well-resolved catalytic site of this GTPase bound to native GTP provides insight into the stalled GTP hydrolysis observed for NRAS-Q61K.

Keywords:  Crystal structure; Induced fit; NRAS; Oncogenic mutation; RAS superfamily small GTPases

DOI:  https://doi.org/10.1016/j.ejcb.2024.151414
Stem Cell Res Ther. 2024 Apr 16. 15(1): 106

Monoallelic KRAS (G13C) mutation triggers dysregulated expansion in induced pluripotent stem cell-derived hematopoietic progenitor cells.

Huan-Ting Lin, Masatoshi Takagi, Kenji Kubara, Kazuto Yamazaki, Fumiko Michikawa, Takashi Okumura, Takuya Naruto, Tomohiro Morio, Koji Miyazaki, Hideki Taniguchi, Makoto Otsu.

   BACKGROUND: Although oncogenic RAS mutants are thought to exert mutagenic effects upon blood cells, it remains uncertain how a single oncogenic RAS impacts non-transformed multipotent hematopoietic stem or progenitor cells (HPCs). Such potential pre-malignant status may characterize HPCs in patients with RAS-associated autoimmune lymphoproliferative syndrome-like disease (RALD). This study sought to elucidate the biological and molecular alterations in human HPCs carrying monoallelic mutant KRAS (G13C) with no other oncogene mutations.
METHODS: We utilized induced pluripotent stem cells (iPSCs) derived from two unrelated RALD patients. Isogenic HPC pairs harboring either wild-type KRAS or monoallelic KRAS (G13C) alone obtained following differentiation enabled reliable comparative analyses. The compound screening was conducted with an established platform using KRAS (G13C) iPSCs and differentiated HPCs.
RESULTS: Cell culture assays revealed that monoallelic KRAS (G13C) impacted both myeloid differentiation and expansion characteristics of iPSC-derived HPCs. Comprehensive RNA-sequencing analysis depicted close clustering of HPC samples within the isogenic group, warranting that comparative studies should be performed within the same genetic background. When compared with no stimulation, iPSC-derived KRAS (G13C)-HPCs showed marked similarity with the wild-type isogenic control in transcriptomic profiles. After stimulation with cytokines, however, KRAS (G13C)-HPCs exhibited obvious aberrant cell-cycle and apoptosis responses, compatible with "dysregulated expansion," demonstrated by molecular and biological assessment. Increased BCL-xL expression was identified amongst other molecular changes unique to mutant HPCs. With screening platforms established for therapeutic intervention, we observed selective activity against KRAS (G13C)-HPC expansion in several candidate compounds, most notably in a MEK- and a BCL-2/BCL-xL-inhibitor. These two compounds demonstrated selective inhibitory effects on KRAS (G13C)-HPCs even with primary patient samples when combined.
CONCLUSIONS: Our findings indicate that a monoallelic oncogenic KRAS can confer dysregulated expansion characteristics to non-transformed HPCs, which may constitute a pathological condition in RALD hematopoiesis. The use of iPSC-based screening platforms will lead to discovering treatments that enable selective inhibition of RAS-mutated HPC clones.

Keywords:  Apoptosis regulatory proteins; Biological models; Cell cycle; Hematopoietic system; Human-induced pluripotent stem cells; Inhibitors; KRAS protein; Lymphoproliferative disorders; Oncogene; Stem cells

DOI:  https://doi.org/10.1186/s13287-024-03723-2
Nat Commun. 2024 Apr 18. 15(1): 3363

Membrane to cortex attachment determines different mechanical phenotypes in LGR5+ and LGR5- colorectal cancer cells.

Sefora Conti, Valeria Venturini, Adrià Cañellas-Socias, Carme Cortina, Juan F Abenza, Camille Stephan-Otto Attolini, Emily Middendorp Guerra, Catherine K Xu, Jia Hui Li, Leone Rossetti, Giorgio Stassi, Pere Roca-Cusachs, Alba Diz-Muñoz, Verena Ruprecht, Jochen Guck, Eduard Batlle, Anna Labernadie, Xavier Trepat.

Colorectal cancer (CRC) tumors are composed of heterogeneous and plastic cell populations, including a pool of cancer stem cells that express LGR5. Whether these distinct cell populations display different mechanical properties, and how these properties might contribute to metastasis is poorly understood. Using CRC patient derived organoids (PDOs), we find that compared to LGR5- cells, LGR5+ cancer stem cells are stiffer, adhere better to the extracellular matrix (ECM), move slower both as single cells and clusters, display higher nuclear YAP, show a higher survival rate in response to mechanical confinement, and form larger transendothelial gaps. These differences are largely explained by the downregulation of the membrane to cortex attachment proteins Ezrin/Radixin/Moesin (ERMs) in the LGR5+ cells. By analyzing single cell RNA-sequencing (scRNA-seq) expression patterns from a patient cohort, we show that this downregulation is a robust signature of colorectal tumors. Our results show that LGR5- cells display a mechanically dynamic phenotype suitable for dissemination from the primary tumor whereas LGR5+ cells display a mechanically stable and resilient phenotype suitable for extravasation and metastatic growth.

DOI: https://doi.org/10.1038/s41467-024-47227-2
Sci Adv. 2024 Apr 19. 10(16): eadj1987

Tissue-specific genetic variation suggests distinct molecular pathways between body shape phenotypes and colorectal cancer.

Laia Peruchet-Noray, Anja M Sedlmeier, Niki Dimou, Hansjörg Baurecht, Béatrice Fervers, Emma Fontvieille, Julian Konzok, Kostas K Tsilidis, Sofia Christakoudi, Anna Jansana, Reynalda Cordova, Patricia Bohmann, Michael J Stein, Andrea Weber, Stéphane Bézieau, Hermann Brenner, Andrew T Chan, Iona Cheng, Jane C Figueiredo, Koldo Garcia-Etxebarria, Victor Moreno, Christina C Newton, Stephanie L Schmit, Mingyang Song, Cornelia M Ulrich, Pietro Ferrari, Vivian Viallon, Robert Carreras-Torres, Marc J Gunter, Heinz Freisling.

It remains unknown whether adiposity subtypes are differentially associated with colorectal cancer (CRC). To move beyond single-trait anthropometric indicators, we derived four multi-trait body shape phenotypes reflecting adiposity subtypes from principal components analysis on body mass index, height, weight, waist-to-hip ratio, and waist and hip circumference. A generally obese (PC1) and a tall, centrally obese (PC3) body shape were both positively associated with CRC risk in observational analyses in 329,828 UK Biobank participants (3728 cases). In genome-wide association studies in 460,198 UK Biobank participants, we identified 3414 genetic variants across four body shapes and Mendelian randomization analyses confirmed positive associations of PC1 and PC3 with CRC risk (52,775 cases/45,940 controls from GECCO/CORECT/CCFR). Brain tissue-specific genetic instruments, mapped to PC1 through enrichment analysis, were responsible for the relationship between PC1 and CRC, while the relationship between PC3 and CRC was predominantly driven by adipose tissue-specific genetic instruments. This study suggests distinct putative causal pathways between adiposity subtypes and CRC.

DOI: https://doi.org/10.1126/sciadv.adj1987