bims-pimaco 2024-05-26 papers

Issue of 2024–05–26
six papers selected by
Lucas B. Zeiger

Cell Rep. 2024 May 23. pii: S2211-1247(24)00598-9. [Epub ahead of print]43(6): 114270

Dark force rising: Reawakening and targeting of fetal-like stem cells in colorectal cancer.

Sigrid K Fey, Nuria Vaquero-Siguero, Rene Jackstadt.

Stem cells play pivotal roles in maintaining intestinal homeostasis, orchestrating regeneration, and in key steps of colorectal cancer (CRC) initiation and progression. Intriguingly, adult stem cells are reduced during many of these processes. On the contrary, primitive fetal programs, commonly detected in development, emerge during tissue repair, CRC metastasis, and therapy resistance. Recent findings indicate a dynamic continuum between adult and fetal stem cell programs. We discuss critical mechanisms facilitating the plasticity between stem cell states and highlight the heterogeneity observed upon the appearance of fetal-like states. We focus on therapeutic opportunities that arise by targeting fetal-like CRC cells and how those concepts can be translated into the clinic.

Keywords: CP: Cancer; CP: Stem cell research

DOI: https://doi.org/10.1016/j.celrep.2024.114270

Curr Opin Cell Biol. 2024 May 21. pii: S0955-0674(24)00051-6. [Epub ahead of print]88 102372

Phosphatidylinositol 3,4-bisphosphate: Out of the shadows and into the spotlight.

Jayatee Ray, David G Sapp, Gregory D Fairn.

Phosphoinositide 3-kinases regulate many cellular functions, including migration, growth, proliferation, and cell survival. Early studies equated the inhibition of Class I PI3Ks with loss of; phosphatidylinositol 3,4,5-trisphosphate (PIP3), but over time, it was realised that these; treatments also depleted phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2). In recent years, the; use of better tools and an improved understanding of its metabolism have allowed for the; identification of specific roles of PI(3,4)P2. This includes the production of PI(3,4)P2 and the; activation of its effector Akt2 in response to growth factor signalling. In contrast, a lysosomal pool of PI(3,4)P2 is a negative regulator of mTORC1 during growth factor deprivation. A growing body of literature also demonstrates that PI(3,4)P2 controls many dynamic plasmalemmal processes. The significance of PI(3,4)P2 in cell biology is increasingly evident.

Keywords: AKT; PI(3,4)P(2); Phosphoinositides; Signal transduction; endocytosis; mTOR; migration

DOI: https://doi.org/10.1016/j.ceb.2024.102372

Int Rev Cell Mol Biol. 2024 ;pii: S1937-6448(24)00015-7. [Epub ahead of print]386 167-222

Targeting KRAS and SHP2 signaling pathways for immunomodulation and improving treatment outcomes in solid tumors.

Priyanka Sahu, Ankita Mitra, Anirban Ganguly.

Historically, KRAS has been considered 'undruggable' inspite of being one of the most frequently altered oncogenic proteins in solid tumors, primarily due to the paucity of pharmacologically 'druggable' pockets within the mutant isoforms. However, pioneering developments in drug design capable of targeting the mutant KRAS isoforms especially KRASG12C-mutant cancers, have opened the doors for emergence of combination therapies comprising of a plethora of inhibitors targeting different signaling pathways. SHP2 signaling pathway, primarily known for activation of intracellular signaling pathways such as KRAS has come up as a potential target for such combination therapies as it emerged to be the signaling protein connecting KRAS and the immune signaling pathways and providing the link for understanding the overlapping regions of RAS/ERK/MAPK signaling cascade. Thus, SHP2 inhibitors having potent tumoricidal activity as well as role in immunomodulation have generated keen interest in researchers to explore its potential as combination therapy in KRAS mutant solid tumors. However, the excitement with these combination therapies need to overcome challenges thrown up by drug resistance and enhanced toxicity. In this review, we will discuss KRAS and SHP2 signaling pathways and their roles in immunomodulation and regulation of tumor microenvironment and also analyze the positive effects and drawbacks of the different combination therapies targeted at these signaling pathways along with their present and future potential to treat solid tumors.

Keywords: Combination therapies; Immunomodulation; KRAS; MEK; SHP2; TME

DOI: https://doi.org/10.1016/bs.ircmb.2024.01.005

Nat Struct Mol Biol. 2024 May 21.

eIF4A1 enhances LARP1-mediated translational repression during mTORC1 inhibition.

Yuichi Shichino, Tomokazu Yamaguchi, Kazuhiro Kashiwagi, Mari Mito, Mari Takahashi, Takuhiro Ito, Nicholas T Ingolia, Keiji Kuba, Shintaro Iwasaki.

Eukaryotic translation initiation factor (eIF)4A-a DEAD-box RNA-binding protein-plays an essential role in translation initiation. Recent reports have suggested helicase-dependent and helicase-independent functions for eIF4A, but the multifaceted roles of eIF4A have not been fully explored. Here we show that eIF4A1 enhances translational repression during the inhibition of mechanistic target of rapamycin complex 1 (mTORC1), an essential kinase complex controlling cell proliferation. RNA pulldown followed by sequencing revealed that eIF4A1 preferentially binds to mRNAs containing terminal oligopyrimidine (TOP) motifs, whose translation is rapidly repressed upon mTORC1 inhibition. This selective interaction depends on a La-related RNA-binding protein, LARP1. Ribosome profiling revealed that deletion of EIF4A1 attenuated the translational repression of TOP mRNAs upon mTORC1 inactivation. Moreover, eIF4A1 increases the interaction between TOP mRNAs and LARP1 and, thus, ensures stronger translational repression upon mTORC1 inhibition. Our data show the multimodality of eIF4A1 in modulating protein synthesis through an inhibitory binding partner and provide a unique example of the repressive role of a universal translational activator.

DOI: https://doi.org/10.1038/s41594-024-01321-7

Int J Mol Sci. 2024 May 20. pii: 5565. [Epub ahead of print]25(10):

EGFR and PI3K Signalling Pathways as Promising Targets on Circulating Tumour Cells from Patients with Metastatic Gastric Adenocarcinoma.

Ann-Katrin Piper, Chelsea Penney, Jacqueline Holliday, Gary Tincknell, Yafeng Ma, Sarbar Napaki, Klaus Pantel, Daniel Brungs, Marie Ranson.

The prognosis for metastatic gastric adenocarcinoma (mGAC) remains poor. Gene alterations in receptor tyrosine kinases (RTKs) such as epidermal growth factor receptor (EGFR) and their downstream effectors including catalytic subunit alpha of the phosphatidylinositol 3-kinase (PIK3CA) are common in mGAC. Targeted RTK and phosphatidylinositol-3-kinase (PI3K) treatments have demonstrated clinical benefits in other solid tumours and are key potential targets for clinical development against mGAC given the presence of recurrent alterations in these pathways. Furthermore, combination RTK/PI3K treatments may overcome compensatory mechanisms that arise using monotherapies, leading to improved patient outcomes. Herein, we investigated RTK/PI3K single and combination drug responses against our unique human mGAC-derived PIK3CA gain-of-function mutant, human epidermal growth factor receptor 2 (HER2)-negative, EGFR-expressing circulating tumour cell line, UWG02CTC, under two- and three-dimensional culture conditions to model different stages of metastasis. UWG02CTCs were highly responsive to the PI3K p110α-subunit targeted drugs PIK-75 (IC50 = 37.0 ± 11.1 nM) or alpelisib (7.05 ± 3.7 µM). Drug sensitivities were significantly increased in 3D conditions. Compensatory MAPK/ERK pathway upregulation by PI3K/Akt suppression was overcome by combination treatment with the EGFR inhibitor gefitinib, which was strongly synergistic. PIK-75 plus gefitinib significantly impaired UWG02CTC invasion in an organotypic assay. In conclusion, UWG02CTCs are a powerful ex vivo mGAC drug responsiveness model revealing EGFR/PI3K-targeted drugs as a promising combination treatment option for HER2-negative, RAS wild-type mGAC patients.

Keywords: 3D cell culture; EGFR; PI3K/Akt; PIK-75; alpelisib; c-Met; cell signalling; circulating tumour cells; gastric cancer; gefitinib; organotypics

DOI: https://doi.org/10.3390/ijms25105565

Int J Biol Macromol. 2024 May 19. pii: S0141-8130(24)03282-3. [Epub ahead of print]270(Pt 2): 132477

A novel Imidazo[1,2-a]pyridine derivative modulates active KRASG12D through off-like conformational shifts in switch-I and switch-II regions, mimicking inactive KRASG12D.

Yasir Ali, Azmat Ali Khan, Amer M Alanazi, Shabeen Fatima, Stanislav Kozmon.

KRASG12D are the most prevalent oncogenic mutations and a promising target for solid tumor therapies. However, its inhibition exhibits tremendous challenge due to the necessity of high binding affinity to obviate the need for covalent binders. Here we report the evidence of a novel class of Imidazo[1,2-a]pyridine derivative as potentially significant novel inhibitors of KRASG12D, discovered through extensive ligand-based screening against 2-[(2R)-piperidin-2-yl]-1H-indole, an important scaffold for KRASG12D inhibition via switch-I/II (S-I/II) pocket. The proposed compounds exhibited similar binding affinities and overlapped pose configurations to 2-[(2R)-piperidin-2-yl]-1H-indole, serving as a reliable starting point for drug discovery. Comparative free energy profiles demonstrated that C4 [2-methyl-3-((5-phenyl-1H-1,2,4-triazol-3-yl)methyl)imidazo[1,2-a]pyridine] effectively shifted the protein to a stable low-energy conformation via a prominent transition state. The conformational changes across the transition revealed the conformational shift of switch-I and II to a previously known off-like conformation of inactive KRASG12D with rmsd of 0.91 Å. These conformations were even more prominent than the privileged scaffold 2-[(2R)-piperidin-2-yl]-1H-indole. The representative structure overlay of C4 and another X-ray crystallography solved BI-2852 bound inactive KRASG12D revealed that Switch-I and II exhibited off-like conformations. The cumulative variance across the first eigenvalue that accounted for 57 % of the collective variance validated this on-to-off transition. In addition, the relative interaction of C4 binding showed consistent patterns with BI-2852. Taken together, our results support the inhibitory activity of [2-methyl-3-((5-phenyl-1H-1,2,4-triazol-3-yl)methyl)imidazo[1,2-a]pyridine] by shifting active KRASG12D to an inactive conformation.

Keywords: Drug design; Imidazo[1,2-a]pyridine; KRAS(G12D) inhibitors; SI/II-pocket; Tumor suppression

DOI: https://doi.org/10.1016/j.ijbiomac.2024.132477