The IMiD target CRBN determines HSP90 activity toward transmembrane proteins essential in multiple myeloma.

The complex architecture of transmembrane proteins requires quality control (QC) of folding, membrane positioning, and trafficking as prerequisites for cellular homeostasis and intercellular communication. However, it has remained unclear whether transmembrane protein-specific QC hubs exist. Here we identify cereblon (CRBN), the target of immunomodulatory drugs (IMiDs), as a co-chaperone that specifically determines chaperone activity of HSP90 toward transmembrane proteins by means of counteracting AHA1. This function is abrogated by IMiDs, which disrupt the interaction of CRBN with HSP90. Among the multiple transmembrane protein clients of CRBN-AHA1-HSP90 revealed by cell surface proteomics, we identify the amino acid transporter LAT1/CD98hc as a determinant of IMiD activity in multiple myeloma (MM) and present an Anticalin-based CD98hc radiopharmaceutical for MM radio-theranostics. These data establish the CRBN-AHA1-HSP90 axis in the biogenesis of transmembrane proteins, link IMiD activity to tumor metabolism, and nominate CD98hc and LAT1 as attractive diagnostic and therapeutic targets in MM.

Functional and Immunologic Mapping of Domains of the Reticulocyte-Binding Protein Plasmodium vivax PvRBP2a.

We previously described a novel Plasmodium vivax invasion mechanism into human reticulocytes via the PvRBP2a-CD98 receptor-ligand pair. Using linear epitope mapping, we assessed the PvRBP2a epitopes involved in CD98 binding and recognized by antibodies from patients who were infected. We identified 2 epitope clusters mediating PvRBP2a-CD98 interaction. Cluster B (PvRBP2a431-448, TAALKEKGKLLANLYNKL) was the target of antibody responses in humans infected by P vivax. Peptides from each cluster were able to prevent live parasite invasion of human reticulocytes. These results provide new insights for development of a malaria blood-stage vaccine against P vivax.

A monoclonal antibody recognizing CD98 on human embryonic stem cells shows anti-tumor activity in hepatocellular carcinoma xenografts.

CD98, also known as SLC3A2, is a multifunctional cell surface molecule consisting of amino acid transporters. CD98 is ubiquitously expressed in many types of tissues, but expressed at higher levels in cancerous tissues than in normal tissues. CD98 is also upregulated in most hepatocellular carcinoma (HCC) patients; however, the function of CD98 in HCC cells has been little studied. In this study, we generated a panel of monoclonal antibodies (MAbs) against surface proteins on human embryonic stem cells (hESCs). NPB15, one of the MAbs, bound to hESCs and various cancer cells, including HCC cells and non-small cell lung carcinoma (NSCLC) cells, but not to peripheral blood mononuclear cells (PBMCs) and primary hepatocytes. Immunoprecipitation and mass spectrometry identified the target antigen of NPB15 as CD98. CD98 depletion decreased cell proliferation, clonogenic survival, and migration and induced apoptosis in HCC cells. In addition, CD98 depletion decreased the expression of cancer stem cell (CSC) markers in HCC cells. In tumorsphere cultures, the expression of CD98 interacting with NPB15 was significantly increased, as were known CSC markers. After cell sorting by NPB15, cells with high expression of CD98 (CD98-high) showed higher clonogenic survival than cells with low expression of CD98 (CD98-low) in HCC cells, suggesting CD98 as a potential CSC marker on HCC cells. The chimeric version of NPB15 was able to induce antibody-dependent cellular cytotoxicity (ADCC) against HCC cells in vitro. NPB15 injection showed antitumor activity in an HCC xenograft mouse model. The results suggest that NPB15 may be developed as a therapeutic antibody for HCC patients.

CD98 regulates the phosphorylation of HER2 and a bispecific anti-HER2/CD98 antibody inhibits the growth signal of human breast cancer cells.

Human epidermal growth factor receptor (HER) family proteins are currently major targets of therapeutic monoclonal antibodies against various epithelial cancers. However, the resistance of cancer cells to HER family-targeted therapies, which may be caused by cancer heterogeneity and persistent HER phosphorylation, often reduces overall therapeutic effects. We herein showed that a newly discovered molecular complex between CD98 and HER2 affected HER function and cancer cell growth. The immunoprecipitation of the HER2 or HER3 protein from lysates of SKBR3 breast cancer (BrCa) cells revealed the HER2-CD98 or HER3-CD98 complex. The knockdown of CD98 by small interfering RNAs inhibited the phosphorylation of HER2 in SKBR3 cells. A bispecific antibody (BsAb) that recognized the HER2 and CD98 proteins was constructed from a humanized anti-HER2 (SER4) IgG and an anti-CD98 (HBJ127) single chain variable fragment, and this BsAb significantly inhibited the cell growth of SKBR3 cells. Prior to the inhibition of AKT phosphorylation, BsAb inhibited the phosphorylation of HER2, however, significant inhibition of HER2 phosphorylation was not observed in anti-HER2 pertuzumab, trastuzumab, SER4 or anti-CD98 HBJ127 in SKBR3 cells. The dual targeting of HER2 and CD98 has potential as a new therapeutic strategy for BrCa.

CD147 regulates the formation and function of immune synapses.

CD147 is a T cell activation-associated molecule which is closely involved in the formation of the immune synapse (IS). However, the precise role of CD147 in T cell activation and IS formation remains unclear. In the present study, we demonstrated that CD147 translocated to the IS upon T cell activation and was primarily distributed in the peripheral super molecular cluster (p-SMAC). The knock down of CD147 expression in T cells, but not in B cells, impaired IS formation. CD147 participated in IS formation between T cells and different types of antigen-presenting cells (APCs), including macrophages and dendritic cells. Ligation of CD147 with its monoclonal antibody (mAb) HAb18 effectively inhibited T cell activation and IL-2 secretion. CD98, a critical molecule interacting with CD147, was distributed in IS in a CD147-dependent way. Phosphorylation levels of T cell receptor (TCR) related molecules, like ZAP-70, ERK, and cJun, were down-regulated by CD147 ligation, which is crucial for the interaction of CD147 and TCR signaling transduction. CD147 is indispensable for the formation of immune synapses and plays an important role in the regulation of its function.

dMyc-dependent upregulation of CD98 amino acid transporters is required for Drosophila brain tumor growth.

Tumor cells have an increased demand for nutrients to sustain their growth, but how these increased metabolic needs are ensured or how this influences tumor formation and progression remains unclear. To unravel tumor metabolic dependencies, particularly from extracellular metabolites, we have analyzed the role of plasma membrane metabolic transporters in Drosophila brain tumors. Using a well-established neural stem cell-derived tumor model, caused by brat knockdown, we have found that 13 plasma membrane metabolic transporters, including amino acid, carbohydrate and monocarboxylate transporters, are upregulated in tumors and are required for tumor growth. We identified CD98hc and several of the light chains with which it can form heterodimeric amino acid transporters, as crucial players in brat RNAi (brat IR) tumor progression. Knockdown of these components of CD98 heterodimers caused a dramatic reduction in tumor growth. Our data also reveal that the oncogene dMyc is required and sufficient for the upregulation of CD98 transporter subunits in these tumors. Furthermore, tumor-upregulated dmyc and CD98 transporters orchestrate the overactivation of the growth-promoting signaling pathway TOR, forming a core growth regulatory network to support brat IR tumor progression. Our findings highlight the important link between oncogenes, metabolism, and signaling pathways in the regulation of tumor growth and allow for a better understanding of the mechanisms necessary for tumor progression.

Melatonin inhibits atherosclerosis progression via galectin-3 downregulation to enhance autophagy and inhibit inflammation.

Autophagy deficiency in macrophages exacerbates inflammation in atherosclerosis (AS), and recently, galectin-3 (Gal-3) has been implicated as a critical promoter of inflammation in AS. Further, melatonin (Mel) exerts an autophagy-promoting effect in many chronic inflammatory diseases. In this study, we aimed to investigate whether Mel inhibits AS progression by downregulating Gal-3 to enhance autophagy and inhibit inflammation. Thus, we performed in vivo and in vitro experiments using high-fat diet (HFD)-fed ApoE-/-  mice and THP-1 macrophages, respectively. Smart-seq of AS plaque macrophages revealed that the differentially expressed genes (DEGs) downregulated by Mel were enriched in immune-related processes, and changes in inflammation status were confirmed based on lower levels of proinflammatory factors in Mel-treated HFD-fed ApoE-/-  mice and THP-1 macrophages. Further, via transcriptome-based multiscale network pharmacology platform (TMNP), the upstream target genes of the smart-seq DEGs were identified, and Gal-3 showed a high score. Gal-3 was downregulated both in vivo and in vitro by Mel treatment. Besides, the enrichment of the target genes predicted via the TMNP method indicated that autophagy considerably affected the DEGs. Mel treatment as well as Gal-3 knockdown downregulated most inflammatory response-related proteins could attribute to enhancing autophagy. Mechanistically, Mel treatment inhibited Gal-3 leading to lowering the activity of the nuclear transcription factor-kappa B (NF-κB) pathway, and promoting the nuclear localization of transcription factor EB (TFEB). However, increased secretion of Gal-3 activated the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway and impaired autophagy via binding to CD98. Thus, Mel promoted autophagy and restrained inflammation by downregulating Gal-3, implying that it holds promise as a treatment for AS.

Mast cell surfaceome characterization reveals CD98 heavy chain is critical for optimal cell function.

BACKGROUND: Mast cells are involved in many distinct pathologic conditions, suggesting that they recognize and respond to various stimuli and thus require a rich repertoire of cell surface proteins. However, mast cell surface proteomes have not been comprehensively characterized. OBJECTIVE: We aimed to further characterize the mast cell surface proteome to obtain a better understanding of how mast cells function in health and disease. METHODS: We enriched for glycosylated surface proteins expressed in mouse bone marrow-derived cultured mast cells (BMCMCs) and identified them using mass spectrometry analysis. The presence of novel surface proteins in mast cells was validated by real-time quantitative PCR and flow cytometry analysis in BMCMCs and peritoneal mast cells (PMCs). We developed a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene editing approach to disrupt genes of interest in BMCMCs. RESULTS: The glycoprotein enrichment approach resulted in the identification of 1270 proteins in BMCMCs, 378 of which were localized to the plasma membrane. The most common protein classes among plasma membrane proteins were small GTPases, receptors, and transporters. One such cell surface protein was CD98 heavy chain (CD98hc), encoded by the Slc3a2 gene. Slc3a2 gene disruption resulted in a significant reduction in CD98hc expression, adhesion, and proliferation. CONCLUSIONS: Glycoprotein enrichment coupled with mass spectrometry can be used to identify novel surface molecules in mast cells. Moreover, CD98hc plays an important role in mast cell function.

Clinical significance of the CD98hc-CD147 complex in ovarian cancer: a bioinformatics analysis.

Ovarian cancer is one of the most common malignant tumours affecting the female reproductive organs. CD147 (BSG) and CD98hc (SLC3A2) are oncogenes that form the CD98hc-CD147 complex, which regulates the proliferation, metastasis, metabolism, and cell cycle of cancer cells. The roles of the CD98hc-CD147 complex in ovarian cancer remain unclear. We analysed the expression and prognostic value of CD147 and CD98hc in ovarian cancer using the TCGA and ICGC databases. The effect of CD147 and CD98hc on the tumour immune response was analysed using the TIMER database. CD98hc was more highly expressed in normal tissues than primary tumour tissues, while CD147 was more highly expressed in primary tumour tissues than normal tissues. CD98hc expression was significantly associated with neutrophil and dendritic cell levels. CD147 and CD98hc were correlated with DNA repair, the cell cycle, and DNA replication. The CD98hc-CD147 complex could serve as a target for ovarian cancer treatment.

What is already known on this subject? CD98hc and CD147 are oncogenes that induce the proliferation and metastasis of cancer cells. The CD98hc-CD147 complex has been identified as a risk factor for cancer patients and causes resistance to cancer treatment.What do the results of this study add? We confirmed the expression levels of CD98hc and CD147 in ovarian cancer tissues and the effects of these oncogenes on the tumour immune response.What are the implications of these findings for clinical practice and/or further research? The CD98hc-CD147 complex may serve as a new target for ovarian cancer therapy.

[Identifying and targeting multiple myeloma-specific antigens resulting from post-translational protein modifications by CAR-T cell therapies].

CAR-T cell therapy is a twenty-first-century immunotherapy breakthrough. Another breakthrough in immunotherapy is checkpoint antibody therapy, which can treat multiple cancers with a single antibody, whereas CAR-T cell therapy requires an appropriate target for each cancer type. Other than B-cell malignancies, no good target antigen for cancers has been discovered. We have been working on the development of CAR-T cells that target differences in post-translational changes such as conformation or glycosylation, between cancer and normal cells rather than differences in protein expression levels. CAR-T cells specific for activated integrins, which are consistently overexpressed in multiple myeloma, are one of the achievements. We recently discovered an antibody with myeloma specificity despite binding to a ubiquitously expressed protein, CD98hc, and hypothesized that this specificity may be owing to altered N-glycosylation of CD98hc.

Molecular mapping of transmembrane mechanotransduction through the ß1 integrin-CD98hc-TRPV4 axis.

One of the most rapid (less than 4 ms) transmembrane cellular mechanotransduction events involves activation of transient receptor potential vanilloid 4 (TRPV4) ion channels by mechanical forces transmitted across cell surface ß1 integrin receptors on endothelial cells, and the transmembrane solute carrier family 3 member 2 (herein denoted CD98hc, also known as SLC3A2) protein has been implicated in this response. Here, we show that ß1 integrin, CD98hc and TRPV4 all tightly associate and colocalize in focal adhesions where mechanochemical conversion takes place. CD98hc knockdown inhibits TRPV4-mediated calcium influx induced by mechanical forces, but not by chemical activators, thus confirming the mechanospecificity of this signaling response. Molecular analysis reveals that forces applied to ß1 integrin must be transmitted from its cytoplasmic C terminus via the CD98hc cytoplasmic tail to the ankyrin repeat domain of TRPV4 in order to produce ultrarapid, force-induced channel activation within the focal adhesion.

Identification of DNA aptamers that specifically targets EBV+ nasopharyngeal carcinoma via binding with EphA2/CD98hc complex.

Nasopharyngeal carcinoma (NPC) is one of the Epstein-Barr virus (EBV)-associated malignancies and has a distinct geographical distribution. The high mortality rates of NPC patients with advanced and recurrent disease highlight the urgent need for biomarkers for early diagnosis and effective treatments. In this study, we developed DNA aptamers that specifically bind to EBV positive NPC cells by the Cell-SELEX procedure. We further identified the EphA2 (ephrin type-A receptor 2)/CD98hc (CD98 heavy chain) complex as the potential target of the aptamer EA-3 by combining aptamer-based separation and mass spectrometry analysis. Our results revealed for the first time that EphA2 colocalized with CD98hc at the plasma membrane and EphA2 coimmunoprecipitated with CD98hc, which may serve as a starting point for exploring the potential functions of the complex of EphA2 and CD98hc in NPCs. Here, we demonstrated that aptamers can be useful for the identification of protein complexes on the surface of cancer cells.

Heteromeric Solute Carriers: Function, Structure, Pathology and Pharmacology.

Solute carriers form one of three major superfamilies of membrane transporters in humans, and include uniporters, exchangers and symporters. Following several decades of molecular characterisation, multiple solute carriers that form obligatory heteromers with unrelated subunits are emerging as a distinctive principle of membrane transporter assembly. Here we comprehensively review experimentally established heteromeric solute carriers: SLC3-SLC7 amino acid exchangers, SLC16 monocarboxylate/H+ symporters and basigin/embigin, SLC4A1 (AE1) and glycophorin A exchanger, SLC51 heteromer Ost α-Ost ß uniporter, and SLC6 heteromeric symporters. The review covers the history of the heteromer discovery, transporter physiology, structure, disease associations and pharmacology - all with a focus on the heteromeric assembly. The cellular locations, requirements for complex formation, and the functional role of dimerization are extensively detailed, including analysis of the first complete heteromer structures, the SLC7-SLC3 family transporters LAT1-4F2hc, b0,+AT-rBAT and the SLC6 family heteromer B0AT1-ACE2. We present a systematic analysis of the structural and functional aspects of heteromeric solute carriers and conclude with common principles of their functional roles and structural architecture.

Infection by Brucella melitensis or Brucella papionis modifies essential physiological functions of human trophoblasts.

Brucellosis is a zoonosis caused by bacteria of the Brucella genus. In ruminants, brucellosis causes abortion, followed by chronic infection and secretion of bacteria in milk. In humans, it usually presents as flu-like symptoms, with serious complications if untreated. Epidemiological studies have only recently established that brucellosis can also cause pregnancy complications in women, but the pathogenic mechanisms are unknown. Pioneering studies in ruminants showed that Brucella infect trophoblasts and then colonise the placenta where they grow to high density. A recent study showed that the main zoonotic Brucella species can infect human cytotrophoblasts (CTB) and extravillous trophoblasts (EVT). In this work, we show that Brucella papionis (associated with stillbirth in primates) also infects human trophoblasts. However, it replicates actively in CTB, whereas its replication is very restricted within EVT. We also observed alteration of several trophoblastic functions upon infection by B. papionis or Brucella melitensis (the most prevalent species in human brucellosis). Infection altered the production of hormones, the ability of CTB to form syncytiotrophoblasts, and the invasion capacity of EVT. We also found that infection can spread between different types of trophoblasts. These findings constitute a new step in understanding how Brucella infection causes adverse pregnancy outcomes.

Role of CD98 in liver disease.

CD98 is a multifunctional glycoprotein that is involved in various biological processes such as amino acid transport, cell adhesion, diffusion, adhesion, and proliferation. The role of CD98 in liver disease has not thoroughly been examined and is limited reports in the literature. Among these reports, direct association for CD98 in nonalcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC) have been reported. Our lab has reported that targeting CD98 in high fat diet mice reduced steatosis and inflammation in NAFLD. Other reports associate CD98 in HCC due in part to the role of CD98 in activating integrin signaling. Herein, we present CD98 staining on liver biopsies from NAFLD, chronic active hepatitis, cirrhosis, and 3 stages of HCC to demonstrate the upregulation of CD98 expression throughout liver disease progression. In addition, we analyze current literature to elucidate roles and potential roles of CD98 with each stage of liver disease.

Prazosin induced lysosomal tubulation interferes with cytokinesis and the endocytic sorting of the tumour antigen CD98hc.

The quinazoline based drug prazosin (PRZ) is a potent inducer of apoptosis in human cancer cells. We recently reported that PRZ enters cells via endocytosis and induces tubulation of the endolysosomal system. In a proteomics approach aimed at identifying potential membrane proteins with binding affinity to quinazolines, we detected the oncoprotein CD98hc. We confirmed shuttling of CD98hc towards lysosomes and upregulation of CD98hc expression in PRZ treated cells. Gene knockout (KO) experiments revealed that endocytosis of PRZ still occurs in the absence of CD98hc - suggesting that PRZ does not enter the cell via CD98hc but misroutes the protein towards tubular lysosomes. Lysosomal tubulation interfered with completion of cytokinesis and provoked endoreplication. CD98hc KO cells showed reduced endoreplication capacity and lower sensitivity towards PRZ induced apoptosis than wild type cells. Thus, loss of CD98hc does not affect endocytosis of PRZ and lysosomal tubulation, but the ability for endoreplication and survival of cells. Furthermore, we found that glutamine, lysomototropic agents - namely chloroquine and NH4Cl - as well as inhibition of v-ATPase, interfere with the intracellular transport of CD98hc. In summary, our study further emphasizes lysosomes as target organelles to inhibit proliferation and to induce cell death in cancer. Most importantly, we demonstrate for the first time that the intracellular trafficking of CD98hc can be modulated by small molecules. Since CD98hc is considered as a potential drug target in several types of human malignancies, our study possesses translational significance suggesting, that old drugs are able to act on a novel target.

Tracking Dye-Independent Approach to Identify and Isolate In Vitro Expanded T Cells.

T cell proliferation is routinely identified in vitro using tracking dyes or through detecting intracellular upregulation of the nuclear protein, Ki-67. However, labeling with tracking dyes is cumbersome, associated with cellular toxicity, while Ki-67 cannot be used to identify and isolate viable T cells, and both techniques are incompatible with MACS technology. Here, we introduce a simple tool to identify and isolate in vitro T cell expansion that is tracking dye-independent and allows for sorting of viable T cells. We show that CD71, a transferrin receptor, and CD98, a heterodimer glycoprotein involved in both integrin signaling and amino-acid transport, are both highly upregulated on proliferating T cells upon in vitro stimulation, and that CD71 expression is maximal on the more recent progeny T cells, while CD98 upregulation remains stable across different generations of progeny T cells. Moreover, we demonstrate that the upregulation of CD71 and CD98 identifies CFSElow T cells and provides further proof of the antigen-specificity of T cells identified by CD71 and CD98 dual upregulation based on tetramer staining. We further show that CD71 can be used to enrich for in vitro expanding T cells using MACS technology. In conclusion, we show that CD71 and CD98 can be used to identify and isolate expanded T cells following in vitro stimulation and that CD71 is an MACS-compatible alternative to tracking dyes or Ki-67 detection. © 2019 International Society for Advancement of Cytometry.

Deficient glucose uptake is linked to impaired Glut1 expression upon CD3/CD28 stimulation in memory T cells from pleural effusions secondary to lung cancer.

Glucose and nutrient uptake is essential in supporting T cell activation and is increased upon CD3/CD28 stimulation. As T cells from pleural effusions secondary to lung cancer show impaired function, we hypothesized that these cells might have altered expression of nutrient transporters. Here, we analysed by flow cytometry the expression of the transferrin receptor CD71, amino acid transporter CD98 and glucose transporter Glut1 and glucose uptake in pleural effusion-derived T cells from lung cancer patients, after stimulation via CD3/CD28 under normoxia or hypoxia (2% O2 ). We compared the response of T cells from pleural effusions secondary to lung cancer with that of T cells from nonmalignant effusions. In memory T cells from both groups, anti-CD3/CD28-stimulation under normoxia upregulated CD98 and CD71 expression (measured as median fluorescence intensity, MFI) in comparison with anti-CD3-stimulation. Costimulation under hypoxia tended to increase CD98 expression compared to CD3-stimulation in memory T cells from both groups. Remarkably, in the cancer group, memory T cells stimulated via CD3/CD28 under hypoxia failed to increase CD71 and Glut1 expression levels compared to the cells receiving anti-CD3 stimulation, a phenomenon that contrasted with the behaviour of memory T cells from nonmalignant effusions. Consequently, glucose uptake by memory T cells from the cancer group was not increased after CD3/CD28 stimulation under hypoxia, implying that their glycolytic metabolism is defective. As this process is required for inducing an antitumoural response, our study suggests that memory T cells are rendered dysfunctional and are unable to eliminate lung tumour cells.

Sorting of Clathrin-Independent Cargo Proteins Depends on Rab35 Delivered by Clathrin-Mediated Endocytosis.

Clathrin-mediated endocytosis (CME) and clathrin-independent endocytosis (CIE) co-exist in most cells but little is known about their communication and coordination. Here we show that when CME was inhibited, endocytosis by CIE continued but endosomal trafficking of CIE cargo proteins was altered. CIE cargo proteins that normally traffic directly into Arf6-associated tubules after internalization and avoid degradation (CD44, CD98 and CD147) now trafficked to lysosomes and were degraded. The endosomal tubules were also absent and Arf6-GTP levels were elevated. The altered trafficking, loss of the tubular endosomal network and elevated Arf6-GTP levels caused by inhibition of CME were rescued by expression of Rab35, a Rab associated with clathrin-coated vesicles, or its effector ACAPs, Arf6 GTPase activating proteins (GAP) that inactivate Arf6. Furthermore, siRNA knockdown of Rab35 recreated the phenotype of CME ablation on CIE cargo trafficking without altering endocytosis of transferrin. These observations suggest that Rab35 serves as a CME detector and that loss of CME, or Rab35 input, leads to elevated Arf6-GTP and shifts the sorting of CIE cargo proteins to lysosomes and degradation.

Amino Acid Transport Associated to Cluster of Differentiation 98 Heavy Chain (CD98hc) Is at the Cross-road of Oxidative Stress and Amino Acid Availability.

CD98hc functions as an amino acid (AA) transporter (together with another subunit) and integrin signaling enhancer. It is overexpressed in highly proliferative cells in both physiological and pathological conditions. CD98hc deletion induces strong impairment of cell proliferation in vivo and in vitro Here, we investigate CD98hc-associated AA transport in cell survival and proliferation. By using chimeric versions of CD98hc, the two functions of the protein can be uncoupled. Although recovering the CD98hc AA transport capacity restores the in vivo and in vitro proliferation of CD98hc-null cells, reconstitution of the integrin signaling function of CD98hc is unable to restore in vitro proliferation of those cells. CD98hc-associated transporters (i.e. xCT, LAT1, and y(+)LAT2 in wild-type cells) are crucial to control reactive oxygen species and intracellular AA levels, thus sustaining cell survival and proliferation. Moreover, in CD98hc-null cells the deficiency of CD98hc/xCT cannot be compensated, leading to cell death by ferroptosis. Supplementation of culture media with ß-mercaptoethanol rescues CD98hc-deficient cell survival. Under such conditions null cells show oxidative stress and intracellular AA imbalance and, consequently, limited proliferation. CD98hc-null cells also present reduced intracellular levels of branched-chain and aromatic amino acids (BCAAs and ARO AAs, respectively) and induced expression of peptide transporter 1 (PEPT1). Interestingly, external supply of dipeptides containing BCAAs and ARO AAs rescues cell proliferation and compensates for impaired uptake of CD98hc/LAT1 and CD98hc/y(+)LAT2. Our data establish CD98hc as a master protective gene at the cross-road of redox control and AA availability, making it a relevant therapeutic target in cancer.