Biology subjects

Rocchi, S.

Publications and source records attributed to Rocchi, S..

6 recordsLinked to original sources

bioRxiv2026

Arginine synthesis pathway and ASS1 play a critical role in mRNA translation reprogramming and ICI resistance in cutaneous melanoma

Immune checkpoint inhibitors (ICI) have revolutionized cancer treatment, but their efficacy has now reached a plateau. ICIs are the first class of treatment targeting the crosstalk between immune and tumor cells, making it crucial to understand the complex interactions within the tumor microenvironment (TME) to enhance therapeutic responses. The elevated consumption of resources by cancer cells, coupled with limited vascularization, often results in a TME that is deficient in nutrients, leading to competition for resources between cancer and stromal cells. Consequently, targeting tumor metabolism has emerged as a promising strategy to improve the efficacy of ICIs. Through metabolomic analysis, we have identified metabolic alterations in melanoma cells that are resistant to ICIs, specifically an increase in arginine synthesis and upregulation of ASS1, the rate-limiting enzyme in this pathway. By using gain and loss of function models, as well as a pharmacological inhibitor specific for ASS1, we demonstrated that modulations in the expression or activity of ASS1 is associated with translational reprogramming, characterized by an inhibition of the cap-dependent mRNA translation mediated through mTORC1/4EBP1 axis. We also demonstrated that targeting ASS1 in vivo, resensitize tumors initially resistant to ICI. Taken together, our results highlight the interaction between modulations of arginine synthesis pathway, mRNA translation reprogramming, antitumor immunity, and restauration of sensitivity to anti-PD-1. Our work also demonstrates the therapeutic potential of targeting arginine synthesis pathway, and especially ASS1, to offer new treatments to patients suffering from cutaneous melanoma resistant to ICIs.

cancer biology↗

bioRxiv2025

MELK controls tumor metabolism to promote resistance to melanoma therapy

Melanoma is the most aggressive form of skin cancer, and despite major advances in targeted and immune therapies, durable responses remain limited due to the emergence of resistance mechanisms. Metabolic reprogramming has emerged as a key driver of therapy resistance, allowing tumor cells to adapt to environmental and therapeutic pressures. Here, we identify the maternal embryonic leucine zipper kinase (MELK) as a critical mediator of resistance in melanoma. We demonstrate that MELK stimulates intracellular accumulation of amino acids, leading to activation of mTORC1 signaling and enhanced mitochondrial metabolism and biogenesis. This metabolic shift promotes resistance to immune checkpoint blockade. Importantly, preclinical MELK inhibition sensitizes resistant melanoma cells to immunotherapy, revealing a potential combinatorial strategy to overcome resistance. Our findings establish MELK as a central regulator of metabolic adaptation and therapeutic resistance in melanoma, highlighting its potential as a promising therapeutic target.

cancer biology↗

bioRxiv2024

Single-Nuclei Analysis of the Unfolded Protein Response (SNUPR): A Novel Method revealing bortezomib resistance mechanisms in Multiple Myeloma

AbstractThe unfolded protein response (UPR) is a key stress resistance pathway that has become a key potential target for improving the efficacy of cancer chemotherapy. The UPR involves the activation of three ER-resident stress sensors: PERK, IRE-1 and ATF6 with different signalling outcomes leading to cell death or survival. These cell-fate decisions are difficult to predict and are the result of the complex interaction of PERK, IRE-1 and ATF6 downstream events that have differences in their dynamics and their interplay. These characteristics of the UPR are still poorly defined due to lack of methods to monitor their activation simultaneously at single-cell level. We developed SNUPR (Single Nuclei analysis of the Unfolded Protein Response), an accessible technique that allows the profiling of the three UPR branches in nuclear suspensions by flow cytometry, and applied it to study UPR dynamics in a cancer-specific context. By performing transcriptomic analysis, we found that ER-stress sensor specific gene signatures correlate with patient survival in several blood malignancies, and by using SNUPR, we detected high heterogeneity during UPR activation in vitro in different human cancer cell lines, which could not be have been predicted by the level of expression of the sensors. Our SNUPR analyses further indicate that this heterogeneity is explained by variations in the intensity and duration of ER stress-induced protein synthesis inhibition via PERK, acting as upstream regulator of both the IRE-1/XBP1 and ATF6 dependent transcriptional programs. We extend the relevance of these observations by demonstrating that IRE-1/XBP1s pathway plays a critical role in bortezomib resistance of multiple myeloma cells and patients. We present here SNUPR, that can be used to monitor UPR dynamics with single-cell resolution and identified clinical contexts in which targeting a specific UPR branch could be detrimental or help circumventing chemotherapy resistance. One Sentence SummarySNUPR method enable single-cell UPR profiling and reveals the role of IRE-1 axis in predicting bortezomib resistance in multiple myeloma. HighlightsO_LISNUPR allows simultaneous profiling of PERK, IRE-1 and ATF6 activation with single- cell resolution. C_LIO_LIInhibition of protein synthesis via PERK control the activation levels of the IRE-1/XBP1s and ATF6 pathway. C_LIO_LIIRE-1 activation and associated transcriptional signatures predict the outcome of patients with multiple myeloma treated with Bortezomib. C_LIO_LIIRE-1 activity, but not PERK or ATF6, is essential to acquire bortezomib resistance in multiple myeloma cell lines. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=190 HEIGHT=200 SRC="FIGDIR/small/617161v2_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@297668org.highwire.dtl.DTLVardef@1cab0eorg.highwire.dtl.DTLVardef@2238b4org.highwire.dtl.DTLVardef@b8ebf6_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2024

Induction of the ISR by AB5 subtilase cytotoxin drives IFN-I expression in pDCs via STING activation

We demonstrate that exposure to the AB5 subtilase cytotoxin (SubAB) induces the unfolded protein response (UPR) in human peripheral blood mononuclear cells, concomitant with a pro-inflammatory response across distinct cell subsets. Notably, SubAB selectively induces type-I interferon (IFN) expression in plasmacytoid dendritic cells, acting synergistically with Toll-like receptor 7 stimulation. The induction of type-I IFN in response to SubAB relies on stimulator of interferon genes (STING) activation, coupled with protein synthesis inhibition mediated by protein kinase R-like endoplasmic reticulum kinase and phosphorylation of the eukaryotic translation initiation factor 2 subunit-alpha. By impeding mRNA translation through the integrated stress response, SubAB precipitates the downregulation of the negative innate signaling feedback regulator Tax1-binding protein 1. This downregulation is necessary to unleash TANK-binding kinase 1 signaling associated with STING activation. These findings shed new light on how UPR-inducing conditions may regulate the immune system during infection or pathogenesis.

immunology↗

bioRxiv2024

Dual targeting of GPX4 and TXNRD1 triggers eradication of AML cells through induction of apoptosis and ferroptosis

MyeloDysplastic Syndromes (MDS) are a group of heterogeneous hematological disorders characterized by bone marrow failure and abnormal hematopoietic cell expansion, often progressing to acute myeloid leukemia (AML). Current treatments for AML and high-risk MDS have limited efficacy, requiring the exploration of new therapeutic approaches. Recent research highlighted the potential of inducing cell death through ferroptosis, either independently or alongside traditional chemotherapy, as promising approaches for treating MDS/AML cells. We described here two novel compounds, HA344 and #231, capable of targeting both ferroptosis and apoptosis, leading to the effective eradication of cell lines and primary blasts from MDS/AML patients, while sparing normal hematopoietic cells. RNASeq analysis identified oxidation reduction and apoptotic processes as highly significant induced pathways in two different AML cell lines. Using click-chemistry approaches coupled to mass spectrometry, we identified glutathione peroxidase 4 (GPX4) and thioredoxin reductase 1 (TXNRD1) as the main targets of HA344 and #231 in a large panel of AML cells. Accordingly, both compounds inhibited GPX4 and TXNRD1 activity in the micromolar range and triggered GPX4 degradation. Moreover, using recombinant GPX4 carrying or not a selenium (GPX4-Se and GPX4-S), we confirmed by mass spectrometry that HA344 and #231 bind more efficiently GPX4-Se than GPX4-S. In conclusion, these compounds might represent a new pharmacological approach in the treatment of MDS and AML, offering a potential avenue for future therapies.

biochemistry↗

bioRxiv2020

Translatome-based classification reveals a dual metabolic dependency of a new tumor subtype of pancreatic cancer.

Molecular profiling of Pancreatic Ductal Adenocarcinoma (PDA), based on transcriptomic analyses, identifies two main prognostic subtypes (basal-like and classical), but does not allow personalized first-line treatment. To date, tumors have not been profiled based on protein synthesis rates, yet the step of mRNA translation is highly deregulated in both PDA cancer cells and their microenvironment. Using a collection of twenty-seven pancreatic Patient-Derived Xenografts (PDX), we performed genome-wide analysis of translated mRNA (translatome). Unsupervised bioinformatics analysis revealed a new tumor subtype harboring a low protein synthesis rate, but associated with a robust translation of mRNAs encoding effectors of the integrated stress response (ISR), including the transcription factor ATF4. Functional characterization of the "ISR-activated" human cancer cells revealed a high resistance to drugs, low autophagic capacities, and importantly, metabolic impairments in the serine synthesis and transsulfuration pathways. Overall, our study highlights the strength of translatomic profiling on PDA, which here revealed an unforeseen drug-resistant cancer cell phenotype, whose auxotrophy to both serine and cysteine may be amenable to targeted therapy.

cancer biology↗