scholarly journals Oncogenic KRAS engages an RSK1/NF1 pathway to inhibit wild-type RAS signaling in pancreatic cancer

2021 ◽  
Vol 118 (21) ◽  
pp. e2016904118
Author(s):  
Derek K. Cheng ◽  
Tobiloba E. Oni ◽  
Jennifer S. Thalappillil ◽  
Youngkyu Park ◽  
Hsiu-Chi Ting ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Clinical Success ◽  
Treatment Options ◽  
Mass Spectrometry Analysis ◽  
Ductal Adenocarcinoma ◽  
Ras Signaling ◽  
Wild Type ◽  
Feedback Mechanisms ◽  
Spectrometry Analysis ◽  
Pancreatic Cancer Cells

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy with limited treatment options. Although activating mutations of the KRAS GTPase are the predominant dependency present in >90% of PDAC patients, targeting KRAS mutants directly has been challenging in PDAC. Similarly, strategies targeting known KRAS downstream effectors have had limited clinical success due to feedback mechanisms, alternate pathways, and dose-limiting toxicities in normal tissues. Therefore, identifying additional functionally relevant KRAS interactions in PDAC may allow for a better understanding of feedback mechanisms and unveil potential therapeutic targets. Here, we used proximity labeling to identify protein interactors of active KRAS in PDAC cells. We expressed fusions of wild-type (WT) (BirA-KRAS4B), mutant (BirA-KRAS4BG12D), and nontransforming cytosolic double mutant (BirA-KRAS4BG12D/C185S) KRAS with the BirA biotin ligase in murine PDAC cells. Mass spectrometry analysis revealed that RSK1 selectively interacts with membrane-bound KRASG12D, and we demonstrate that this interaction requires NF1 and SPRED2. We find that membrane RSK1 mediates negative feedback on WT RAS signaling and impedes the proliferation of pancreatic cancer cells upon the ablation of mutant KRAS. Our findings link NF1 to the membrane-localized functions of RSK1 and highlight a role for WT RAS signaling in promoting adaptive resistance to mutant KRAS-specific inhibitors in PDAC.

scholarly journals Oncogenic KRAS engages an RSK1/NF1 complex in pancreatic cancer

2020 ◽  
Author(s):  
Derek K. Cheng ◽  
Tobiloba E. Oni ◽  
Youngkyu Park ◽  
Jennifer S. Thalappillil ◽  
Hsiu-Chi Ting ◽  
...  
Keyword(s):  
Negative Feedback ◽  
Clinical Success ◽  
Treatment Options ◽  
Therapeutic Targets ◽  
Mass Spectrometry Analysis ◽  
Ductal Adenocarcinoma ◽  
Wild Type ◽  
Additional Function ◽  
Feedback Mechanisms ◽  
Spectrometry Analysis

AbstractPancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy with limited treatment options. Although activating mutations of the KRAS GTPase are the predominant dependency present in >90% of PDAC patients, targeting KRAS mutants directly has been challenging in PDAC.Similarly, strategies targeting known KRAS downstream effectors have had limited clinical success due to feedback mechanisms, alternate pathways and toxicity due to the targeting of normal tissues. Therefore, identifying additional functionally relevant KRAS interactions in PDAC may allow for a better understanding of feedback mechanisms and unveil new potential therapeutic targets. Here, we used proximity labelling to identify protein interactors of active KRAS in PDAC cells. Fusions of wildtype (BirA-KRAS4B), mutant (BirA-KRAS4BG12D) and non-transforming and cytosolic double mutant (BirA-KRAS4BG12D/C185S) KRAS with the BirA biotin ligase were expressed in murine PDAC cells. Mass spectrometry analysis revealed that RSK1 was enriched among proteins that selectively interacted with membrane-bound KRASG12D. RSK1 required the NF1 and SPRED proteins to interact with KRAS-GTP at the membrane. In both murine and human PDAC lines, membrane-targeted RSK1 was tolerated but inhibited cell proliferation following oncogenic KRAS abrogation to reveal a negative feedback role for membrane-localized RSK1 on wild-type KRAS. Inhibition of the wild-type KRAS, which has been previously proposed to suppress KRAS oncogenesis, may partially explain how RSK1 has been identified as a dependency in some KRAS mutant cells and may provide an additional function for NF1 in tumorigenesis.Significance StatementFor decades, KRAS interactors have been sought after as potential therapeutic targets in KRAS mutant cancers, especially pancreatic adenocarcinoma (PDAC). Our proximity labeling screen with KRAS in PDAC cells highlight RSK1 as a notable mutant-specific interactor. Functionally, we show that RSK1 mediates negative feedback on wild-type KRAS in PDAC cells.

scholarly journals Metabolic plasticity imparts erlotinib-resistance in pancreatic cancer by upregulating glucose-6-phosphate dehydrogenase

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Neha Sharma ◽  
Alok Bhushan ◽  
Jun He ◽  
Gagan Kaushal ◽  
Vikas Bhardwaj
Keyword(s):  
Pancreatic Cancer ◽  
Drug Resistance ◽  
Cancer Cells ◽  
Treatment Options ◽  
Pentose Phosphate ◽  
Metabolic Phenotype ◽  
Ductal Adenocarcinoma ◽  
Pancreatic Cancer Cells ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Resistant Cells

Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant forms of cancer. Lack of effective treatment options and drug resistance contributes to the low survival among PDAC patients. In this study, we investigated the metabolic alterations in pancreatic cancer cells that do not respond to the EGFR inhibitor erlotinib. We selected erlotinib-resistant pancreatic cancer cells from MiaPaCa2 and AsPC1 cell lines. Metabolic profiling of erlotinib-resistant cells revealed a significant downregulation of glycolytic activity and reduced level of glycolytic metabolites compared to the sensitive cells. The resistant cells displayed elevated expression of the pentose phosphate pathway (PPP) enzymes involved in ROS regulation and nucleotide biosynthesis. The enhanced PPP elevated cellular NADPH/NADP+ ratio and protected the cells from reactive oxygen species (ROS)-induced damage. Inhibition of PPP using 6-aminonicotinamide (6AN) elevated ROS levels, induced G1 cell cycle arrest, and sensitized resistant cells to erlotinib. Genetic studies identified elevated PPP enzyme glucose-6-phosphate dehydrogenase (G6PD) as an important contributor to erlotinib resistance. Mechanistically, our data showed that upregulation of inhibitor of differentiation (ID1) regulates G6PD expression in resistant cells thus contributing to altered metabolic phenotype and reduced response to erlotinib. Together, our results highlight an underlying role of tumor metabolism in PDAC drug response and identify G6PD as a target to overcome drug resistance.

scholarly journals Effects of Growth Hormone on Pancreatic Cancer Derived Exosomes

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A1016-A1017
Author(s):  
Prateek Kulkarni ◽  
Reetobrata Basu ◽  
John J Kopchick
Keyword(s):  
Pancreatic Cancer ◽  
Growth Hormone ◽  
Drug Resistance ◽  
Efflux Pump ◽  
Treatment Options ◽  
The Body ◽  
Ductal Adenocarcinoma ◽  
Gh Treatment ◽  
Mesenchymal Transition ◽  
Pancreatic Cancer Cells

Abstract In 2020, the National Cancer Institute (NCI) estimates 57,600 new cases and 47,050 deaths in the US due to pancreatic ductal adenocarcinoma (PDAC). A dismal 10% five-year overall survival rate in PDAC is attributed to late diagnosis, limited treatment options, a remarkably high metastasis rate, and resistance of this cancer to available therapies. Therefore, a better understanding of the mechanisms of how PDAC tumors acquire drug resistance and spread to distal parts of the body are necessary for developing novel therapeutic approaches. Exosomes, microscopic vesicles released from most cells (both tumor and non-tumor) have been recently established to play a significant role in cell to cell communication. Exosomes modulate their target cell responses systematically depending on the nature of exosomal cargoes (nucleic acids, proteins, and lipids). PDAC derived exosomes have been implicated to promote metastasis via forming a pre-metastatic niche of cells as well as enhancing drug resistance. Growth hormone (GH) secreted primarily by the pituitary gland promotes metastasis and drug resistance as shown by plethora of studies. No study has directly assessed the effect of GH on exosomal cargoes in terms of promoting metastases and drug resistance. In this report, we show that GH modulates various pancreatic cancer cell exosomal cargoes which in turn potentially amplifies tumor invasion and metastases. Our data shows that GH treatment on human and mouse PDAC cells increases the exosomal protein levels of TGFβ - a critical inducer of epithelial-to-mesenchymal transition (EMT, a process leading to metastasis). In addition, GH treatment also increases extracellular matrix-degrading enzymes, MMP2 and 9, as well as multi-drug efflux pump ABCC1, ABCB1, and ABCG2 in PDAC cells. These results strongly implicate GH action in driving EMT and chemoresistance via exosomes in pancreatic cancer. Exosomes have a crucial impact especially in the areas of diagnostics and therapeutics. This report is the first to show that GH modulates the effects of exosomes secreted by pancreatic cancer cells. Acknowledgement: This work was supported in part by the State of Ohio’s Eminent Scholar Program that includes a gift from Milton and Lawrence Goll, by the AMVETS, and Ohio University’s Student Enhancement Award and Edison Biotechnology Institute.

scholarly journals Loss of p53 tumor suppression function drives invasion and genomic instability in models of murine pancreatic cancer

2022 ◽  
Author(s):  
Claudia Tonelli ◽  
Astrid Deschênes ◽  
Melissa A. Yao ◽  
Youngkyu Park ◽  
David A. Tuveson
Keyword(s):  
Pancreatic Cancer ◽  
Mouse Model ◽  
Cancer Progression ◽  
Molecular Mechanisms ◽  
Morphological Changes ◽  
Treatment Options ◽  
Intraepithelial Neoplasia ◽  
Ductal Adenocarcinoma ◽  
Wild Type

Pancreatic ductal adenocarcinoma (PDA) is a deadly disease with few treatment options. There is an urgent need to better understand the molecular mechanisms that drive disease progression, with the ultimate aim of identifying early detection markers and clinically actionable targets. To investigate the transcriptional and morphological changes associated with pancreatic cancer progression, we analyzed the KrasLSLG12D/+; Trp53LSLR172H/+; Pdx1-Cre (KPC) mouse model. We have identified an intermediate cellular event during pancreatic carcinogenesis in the KPC mouse model of PDA that is represented by a subpopulation of tumor cells that express KrasG12D, p53R172H and one allele of wild-type Trp53. In vivo, these cells represent a histological spectrum of pancreatic intraepithelial neoplasia (PanIN) and acinar-to-ductal metaplasia (ADM) and rarely proliferate. Following loss of wild-type p53, these precursor lesions undergo malignant de-differentiation and acquire invasive features. We have established matched organoid cultures of pre-invasive and invasive cells from murine PDA. Expression profiling of the organoids led to the identification of markers of the pre-invasive cancer cells in vivo and mechanisms of disease aggressiveness.

scholarly journals An Essential Role forArgonaute 2in EGFR-KRAS Signaling in Pancreatic Cancer Development

2017 ◽  
Author(s):  
Sunita Shankar ◽  
Jean Ching-Yi Tien ◽  
Ronald F. Siebenaler ◽  
Seema Chugh ◽  
Vijaya L. Dommeti ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Specific Inhibitor ◽  
Genetically Engineered ◽  
Cancer Development ◽  
Ductal Adenocarcinoma ◽  
Ras Signaling ◽  
Biphasic Model ◽  
Genetic Ablation ◽  
Pancreatic Cancer Cells ◽  
Genetically Engineered Mouse Model

KRAS and EGFR are known essential mediators of pancreatic cancer development. In addition, KRAS and EGFR have both been shown to interact with and perturb the function of Argonaute 2 (AGO2), a key regulator of RNA-mediated gene silencing. Here, we employed a genetically engineered mouse model of pancreatic cancer to define the effects of conditional loss ofAGO2inKRASG12D-driven pancreatic cancer. Genetic ablation ofAGO2does not interfere with development of the normal pancreas orKRASG12D-driven early precursor pancreatic intraepithelial neoplasia (PanIN) lesions. Remarkably, however,AGO2is required for progression from early to late PanIN lesions, development of pancreatic ductal adenocarcinoma (PDAC), and metastasis.AGO2ablation permits PanIN initiation driven by the EGFR-RAS axis, but rather than progressing to PDAC, these lesions undergo profound oncogene-induced senescence (OIS). Loss ofTrp53(p53) in this model obviates the requirement ofAGO2for PDAC development. In mouse and human pancreatic tissues, increased expression of AGO2 and elevated co-localization with RAS at the plasma membrane is associated with PDAC progression. Furthermore, phosphorylation of AGO2Y393by EGFR disrupts the interaction of wild-type RAS with AGO2 at the membrane, but does not affect the interaction of mutant KRAS with AGO2. ARS-1620, a G12C-specific inhibitor, disrupts the KRASG12C-AGO2 interaction specifically in pancreatic cancer cells harboring this mutant, demonstrating that the oncogenic KRAS-AGO2 interaction can be pharmacologically targeted. Taken together, our study supports a biphasic model of pancreatic cancer development: anAGO2-independent early phase of PanIN formation reliant on EGFR-RAS signaling, and anAGO2-dependent phase wherein the mutant KRAS-AGO2 interaction is critical to prevent OIS in PanINs and allow progression to PDAC.

scholarly journals Cysteine catabolism and the serine biosynthesis pathway support pyruvate production during pyruvate kinase knockdown in pancreatic cancer cells

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Lei Yu ◽  
Shao Thing Teoh ◽  
Elliot Ensink ◽  
Martin P. Ogrodzinski ◽  
Che Yang ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Cancer Cells ◽  
Pyruvate Kinase ◽  
Metabolic Pathways ◽  
Treatment Options ◽  
Ductal Adenocarcinoma ◽  
Metabolic Enzyme ◽  
Biosynthesis Pathway ◽  
Pancreatic Cancer Cells ◽  
Serine Biosynthesis

Abstract Background Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with limited treatment options. Pyruvate kinase, especially the M2 isoform (PKM2), is highly expressed in PDAC cells, but its role in pancreatic cancer remains controversial. To investigate the role of pyruvate kinase in pancreatic cancer, we knocked down PKM2 individually as well as both PKM1 and PKM2 concurrently (PKM1/2) in cell lines derived from a KrasG12D/-; p53-/- pancreatic mouse model. Methods We used liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine metabolic profiles of wildtype and PKM1/2 knockdown PDAC cells. We further used stable isotope-labeled metabolic precursors and LC-MS/MS to determine metabolic pathways upregulated in PKM1/2 knockdown cells. We then targeted metabolic pathways upregulated in PKM1/2 knockdown cells using CRISPR/Cas9 gene editing technology. Results PDAC cells are able to proliferate and continue to produce pyruvate despite PKM1/2 knockdown. The serine biosynthesis pathway partially contributed to pyruvate production during PKM1/2 knockdown: knockout of phosphoglycerate dehydrogenase in this pathway decreased pyruvate production from glucose. In addition, cysteine catabolism generated ~ 20% of intracellular pyruvate in PDAC cells. Other potential sources of pyruvate include the sialic acid pathway and catabolism of glutamine, serine, tryptophan, and threonine. However, these sources did not provide significant levels of pyruvate in PKM1/2 knockdown cells. Conclusion PKM1/2 knockdown does not impact the proliferation of pancreatic cancer cells. The serine biosynthesis pathway supports conversion of glucose to pyruvate during pyruvate kinase knockdown. However, direct conversion of serine to pyruvate was not observed during PKM1/2 knockdown. Investigating several alternative sources of pyruvate identified cysteine catabolism for pyruvate production during PKM1/2 knockdown. Surprisingly, we find that a large percentage of intracellular pyruvate comes from cysteine. Our results highlight the ability of PDAC cells to adaptively rewire their metabolic pathways during knockdown of a key metabolic enzyme.

Galectin-3 is modulated in pancreatic cancer cells under hypoxia and nutrient deprivation

2020 ◽  
Vol 401 (10) ◽  
pp. 1153-1165 ◽  
Author(s):  
Antônio F. da Silva Filho ◽  
Lucas B. Tavares ◽  
Maira G. R. Pitta ◽  
Eduardo I. C. Beltrão ◽  
Moacyr J. B. M. Rêgo
Keyword(s):  
Pancreatic Cancer ◽  
Cell Death ◽  
Mrna Expression ◽  
Cancer Cells ◽  
Ductal Adenocarcinoma ◽  
Reverse Transcription Pcr ◽  
Pancreatic Cancer Cells ◽  
Through Flow ◽  
Galectin 3

AbstractPancreatic ductal adenocarcinoma is one of the most aggressive tumors with a microenvironment marked by hypoxia and starvation. Galectin-3 has been evaluated in solid tumors and seems to present both pro/anti-tumor effects. So, this study aims to characterize the expression of Galectin-3 from pancreatic tumor cells and analyze its influence for cell survive and motility in mimetic microenvironment. For this, cell cycle and cell death were accessed through flow cytometry. Characterization of inside and outside Galectin-3 was performed through Real-Time Quantitative Reverse Transcription PCR (qRT-PCR), immunofluorescence, Western blot, and ELISA. Consequences of Galectin-3 extracellular inhibition were investigated using cell death and scratch assays. PANC-1 showed increased Galectin-3 mRNA expression when cultivated in hypoxia for 24 and 48 h. After 24 h in simultaneously hypoxic/deprived incubation, PANC-1 shows increased Galectin-3 protein and secreted levels. For Mia PaCa-2, cultivation in deprivation was determinant for the increasing in Galectin-3 mRNA expression. When cultivated in simultaneously hypoxic/deprived condition, Mia PaCa-2 also presented increasing for the Galectin-3 secreted levels. Treatment of PANC-1 cells with lactose increased the death rate when cells were incubated simultaneously hypoxic/deprived condition. Therefore, it is possible to conclude that the microenvironmental conditions modulate the Galectin-3 expression on the transcriptional and translational levels for pancreatic cancer cells.

scholarly journals NR5A2 transcriptional activation by BRD4 promotes pancreatic cancer progression by upregulating GDF15

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Feng Guo ◽  
Yingke Zhou ◽  
Hui Guo ◽  
Dianyun Ren ◽  
Xin Jin ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Cancer Cells ◽  
Cancer Progression ◽  
Transcriptional Activation ◽  
Ductal Adenocarcinoma ◽  
Pancreatic Cancer Cells ◽  
Gene Sets ◽  
And Migration

AbstractNR5A2 is a transcription factor regulating the expression of various oncogenes. However, the role of NR5A2 and the specific regulatory mechanism of NR5A2 in pancreatic ductal adenocarcinoma (PDAC) are not thoroughly studied. In our study, Western blotting, real-time PCR, and immunohistochemistry were conducted to assess the expression levels of different molecules. Wound-healing, MTS, colony formation, and transwell assays were employed to evaluate the malignant potential of pancreatic cancer cells. We demonstrated that NR5A2 acted as a negative prognostic biomarker in PDAC. NR5A2 silencing inhibited the proliferation and migration abilities of pancreatic cancer cells in vitro and in vivo. While NR5A2 overexpression markedly promoted both events in vitro. We further identified that NR5A2 was transcriptionally upregulated by BRD4 in pancreatic cancer cells and this was confirmed by Chromatin immunoprecipitation (ChIP) and ChIP-qPCR. Besides, transcriptome RNA sequencing (RNA-Seq) was performed to explore the cancer-promoting effects of NR5A2, we found that GDF15 is a component of multiple down-regulated tumor-promoting gene sets after NR5A2 was silenced. Next, we showed that NR5A2 enhanced the malignancy of pancreatic cancer cells by inducing the transcription of GDF15. Collectively, our findings suggest that NR5A2 expression is induced by BRD4. In turn, NR5A2 activates the transcription of GDF15, promoting pancreatic cancer progression. Therefore, NR5A2 and GDF15 could be promising therapeutic targets in pancreatic cancer.

Hyperglycemia Promotes Pancreatic Cancer Initiation and Progression by Activating the Wnt/β-Catenin Signaling Pathway

2021 ◽  
Vol 21 ◽  
Author(s):  
Huiming Chen ◽  
Junfeng Zhao ◽  
Ningning Jiang ◽  
Zheng Wang ◽  
Chang Liu
Keyword(s):  
Pancreatic Cancer ◽  
Signaling Pathway ◽  
Precancerous Lesions ◽  
Clinical Specimen ◽  
Ductal Adenocarcinoma ◽  
Dependent Manner ◽  
Pancreatic Cancer Cells ◽  
Cancer Initiation

Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal diseases, with a 5-year survival rate of less than 10% because of the limited knowledge of tumor-promoting factors and their underlying mechanism. Diabetes mellitus (DM) and hyperglycemia are risk factors for many cancers, including PDAC, that modulate multiple downstream signaling pathways, such as the wingless/integrated (Wnt)/β-catenin signaling pathway. However, whether hyperglycemia promotes PDAC initiation and progression by activating the Wnt/β-catenin signaling pathway remains unclear. Methods: In this study, we used bioinformatics analysis and clinical specimen analysis to evaluate the activation states of the Wnt/βcatenin signaling pathway. In addition, colony formation assays, Transwell assays and wound-healing assays were used to evaluate the malignant biological behaviors of pancreatic cancer cells (PCs) under hyperglycemic conditions. To describe the effects of hyperglycemia and the Wnt/β-catenin signaling pathway on the initiation of PDAC, we used pancreatitis-driven pancreatic cancer initiation models in vivo and pancreatic acinar cell 3-dimensional culture in vitro. Results: Wnt/β-catenin signaling pathway-related molecules were overexpressed in PDAC tissues/cells and correlated with poor prognosis in PDAC patients. In addition, hyperglycemia exacerbated the abnormal activation of β-catenin in PDAC and enhanced the malignant biological behaviors of PCs in a Wnt/β-catenin signaling pathway-dependent manner. Indeed, hyperglycemia accelerated the formation of pancreatic precancerous lesions by activating the Wnt/β-catenin signaling pathway in vivo and in vitro. Conclusion: Hyperglycemia promotes pancreatic cancer initiation and progression by activating the Wnt/β-catenin signaling pathway.

scholarly journals Polymyxin B Resistance in El Tor Vibrio cholerae Requires Lipid Acylation Catalyzed by MsbB

2010 ◽  
Vol 192 (8) ◽  
pp. 2044-2052 ◽  
Author(s):  
Jyl S. Matson ◽  
Hyun Ju Yoo ◽  
Kristina Hakansson ◽  
Victor J. DiRita
Keyword(s):  
Antimicrobial Peptides ◽  
Vibrio Cholerae ◽  
Lipid A ◽  
Polymyxin B ◽  
Mass Spectrometry Analysis ◽  
Peptide Antibiotic ◽  
Wild Type ◽  
Spectrometry Analysis ◽  
Antimicrobial Peptide Resistance ◽  
El Tor

ABSTRACTAntimicrobial peptides are critical for innate antibacterial defense. Both Gram-negative and Gram-positive microbes have mechanisms to alter their surfaces and resist killing by antimicrobial peptides. InVibrio cholerae, two natural epidemic biotypes, classical and El Tor, exhibit distinct phenotypes with respect to sensitivity to the peptide antibiotic polymyxin B: classical strains are sensitive and El Tor strains are relatively resistant. We carried out mutant screens of both biotypes, aiming to identify classicalV. choleraemutants resistant to polymyxin B and El TorV. choleraemutants sensitive to polymyxin B. Insertions in a gene annotatedmsbB(encoding a predicted lipid A secondary acyltransferase) answered both screens, implicating its activity in antimicrobial peptide resistance ofV. cholerae. Analysis of a defined mutation in the El Tor biotype demonstrated thatmsbBis required for resistance to all antimicrobial peptides tested. Mutation ofmsbBin a classical strain resulted in reduced resistance to several antimicrobial peptides but in no significant change in resistance to polymyxin B.msbBmutants of both biotypes showed decreased colonization of infant mice, with a more pronounced defect observed for the El Tor mutant. Mass spectrometry analysis showed that lipid A of themsbBmutant for both biotypes was underacylated compared to lipid A of the wild-type isolates, confirming that MsbB is a functional acyltransferase inV. cholerae.

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