Targeting Amino Acid Metabolic Reprogramming via L-Type Amino Acid Transporter 1 (LAT1) for Endocrine-Resistant Breast Cancer

Exploiting the Achilles' heel of cancer: disrupting glutamine metabolism for effective cancer treatment

Cancer cells have adapted to rapid tumor growth and evade immune attack by reprogramming their metabolic pathways. Glutamine is an important nitrogen resource for synthesizing amino acids and nucleotides and an important carbon source in the tricarboxylic acid (TCA) cycle and lipid biosynthesis pathway. In this review, we summarize the significant role of glutamine metabolism in tumor development and highlight the vulnerabilities of targeting glutamine metabolism for effective therapy. In particular, we review the reported drugs targeting glutaminase and glutamine uptake for efficient cancer treatment. Moreover, we discuss the current clinical test about targeting glutamine metabolism and the prospective direction of drug development.

Synthesis and Application of a Near-Infrared Light-Emitting Fluorescent Probe for Specific Imaging of Cancer Cells with High Sensitivity and Selectivity

Background

The preclinical diagnosis of tumors is of great significance to cancer treatment. Near-infrared fluorescence imaging technology is promising for the in-situ detection of tumors with high sensitivity.

Methods

Here, a fluorescent probe was synthesized on the basis of Au nanoclusters with near-infrared light emission and applied to fluorescent cancer cell labeling. Near-infrared methionine-N-Hydroxy succinimide Au nanoclusters (Met-NHs-AuNCs) were prepared successfully by one-pot synthesis using Au nanoclusters, methionine, and N-Hydroxy succinimide as frameworks, reductants, and stabilizers, respectively. The specific fluorescence imaging of tumor cells or tissues by fluorescent probe was studied on the basis of SYBYL Surflex-DOCK simulation model of LAT1 active site of overexpressed receptor on cancer cell surface. The results showed that Met-NHs-AuNCs interacted with the surface of LAT1, and C_Score scored the conformation of the probe and LAT1 as five.

Results

Characterization and in vitro experiments were conducted to explore the Met-NHs-AuNCs targeted uptake of cancer cells. The prepared near-infrared fluorescent probe (Met-NHs-AuNCs) can specifically recognize the overexpression of L-type amino acid transporter 1 (LAT1) in cancer cells so that it can show red fluorescence in cancer cells. Meanwhile, normal cells (H9c2) have no fluorescence.

Conclusion

The fluorescent probe demonstrates the power of targeting and imaging cancer cells.

Amino acids and their roles in tumor immunotherapy of breast cancer

Breast cancer is the most commonly diagnosed cancer among women. The primary treatment options include surgery, radiotherapy, chemotherapy, targeted therapy and hormone therapy. The effectiveness of breast cancer therapy varies depending on the stage and aggressiveness of the cancer, as well as individual factors. Advances in early detection and improved treatments have significantly increased survival rates for breast cancer patients. Nevertheless, specific subtypes of breast cancer, particularly triple-negative breast cancer, still lack effective treatment strategies. Thus, novel and effective therapeutic targets for breast cancer need to be explored. As substrates of protein synthesis, amino acids are important sources of energy and nutrition, only secondly to glucose. The rich supply of amino acids enables the tumor to maintain its proliferative competence through participation in energy generation, nucleoside synthesis and maintenance of cellular redox balance. Amino acids also play an important role in immune-suppressive microenvironment formation. Thus, the biological effects of amino acids may change unexpectedly in tumor-specific or oncogene-dependent manners. In recent years, there has been significant progress in the study of amino acid metabolism, particularly in their potential application as therapeutic targets in breast cancer. In this review, we provide an update on amino acid metabolism and discuss the therapeutic implications of amino acids in breast cancer.

Mitochondrial dynamics as a novel treatment strategy for triple-negative breast cancer

INTRODUCTION

Triple-negative breast cancer (TNBC), recognized as the most heterogeneous type of breast cancer (BC), exhibits a worse prognosis than other subtypes. Mitochondria dynamics play a vital role as mediators in tumorigenesis by adjusting to the cell microenvironments. However, the relationship between mitochondrial dynamics and metabophenotype exhibits discrepancies and divergence across various research and BC models. Therefore, this study aims to explore the role of mitochondrial dynamics in TNBC drug resistance and tumorigenesis.

METHODS

The Wst-8 test was conducted to assess doxorubicin sensitivity in HCC38, MDA-MB-231 (TNBC), and MCF-7 (luminal). Confocal microscopy and FACS were used to quantify the mitochondrial membrane potential (ΔφM), mitophagy, and reactive oxygen species (ROS) production. Agilent Seahorse XF Analyzer was utilized to measure metabolic characteristics. Dynamin-related protein-1 (DRP1), Parkin, and p62 immunohistochemistry staining were performed using samples from 107 primary patients with BC before and after neoadjuvant chemotherapy (NAC).

RESULTS

MDA-MB-231, a TNBC cell line with reduced sensitivity to doxorubicin, reduced ΔφM, and enhanced mitophagy to maintain ROS production through oxidative phosphorylation (OXPHOS)-based metabolism. HCC38, a doxorubicin-sensitive cell line, exhibited no alterations in ΔφM or mitophagy. However, it demonstrated an increase in ROS production and glycolysis. Clinicopathological studies revealed that pretreatment (before NAC) expression of DRP1 was significant in TNBC, as was pretreatment expression of Parkin in the hormone receptor-negative group. Furthermore, low p62 levels seem to be a risk factor for recurrence-free survival.

CONCLUSION

Our findings indicated that the interplay between mitophagy, linked to a worse clinical prognosis, and OXPHOS metabolism promoted chemotherapy resistance in TNBC. Mitochondrial fission is prevalent in TNBC. These findings suggest that targeting the unique mitochondrial metabolism and dynamics in TNBC may offer a novel therapeutic strategy for patients with TNBC.

Prognostic value of amino acid metabolism-related gene expression in invasive breast carcinoma

BACKGROUND

An increasing number of studies indicated that metabolic reprogramming of amino acid metabolism may either promote or inhibit tumor progression. The purpose of this study was to investigate the ability of a gene risk signature associated with amino acid metabolism to predict the prognosis and immune characteristics of invasive breast carcinoma.

METHODS

LASSO Cox regression analysis was performed to construct and validate the prognostic risk signature based on the expression of 9 amino acid metabolism-related genes. The predictive value of the signature, immune characteristics, and chemotherapeutic drugs was also predicted. Finally, 9 significant genes were examined in MDA-MB-231 and MCF-7 cells, and the predicted chemotherapeutic drugs were also verified.

RESULTS

The prognosis of the low-risk group was better than that of the high-risk group. The areas under the curve (AUCs) at 1, 2, and 3 years were 0.852, 0.790, and 0.736, respectively. In addition, the GSEA results for KEGG and GO revealed that samples with a high-risk score exhibited a variety of highly malignant manifestations. The high-risk group was characterized by an increased number of M2 macrophages, a high level of tumor purity, low levels of APC co-stimulation, cytolytic activity, HLA, para-inflammation, and type I IFN response. Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) confirmed that MDA-MB-231 and MCF-7 cells express 9 amino acid metabolism-related genes differently. In addition, cell experiments were conducted to examine the effect of cephaeline-induced on cell viability, migration ability, and protein expression of the PI3K/AKT signaling pathway and HIF-1α.

CONCLUSION

We established a risk signature based on 9 amino acid metabolism-related genes for invasive breast carcinoma. Further analyses revealed that this risk signature is superior to other clinical indexes in survival prediction and that the subgroups identified by the risk signature exhibit distinct immune characteristics. Cephaeline was determined to be a superior option for patients in high-risk groups.

CD98 heavy chain as a prognostic biomarker and target for cancer treatment

The SLC3A2 gene encodes for a cell-surface transmembrane protein CD98hc (4F2). CD98hc serves as a chaperone for LAT1 (SLC7A5), LAT2 (SLC7A8), y+LAT1 (SLC7A7), y+LAT2 (SLC7A6), xCT (SLC7A11) and Asc1 (SLC7A10) providing their recruitment to the plasma membrane. Together with the light subunits, it constitutes heterodimeric transmembrane amino acid transporters. CD98hc interacts with other surface molecules, such as extracellular matrix metalloproteinase inducer CD147 (EMMPRIN) and adhesion receptors integrins, and regulates glucose uptake. In this way, CD98hc connects the signaling pathways sustaining cell proliferation and migration, biosynthesis and antioxidant defense, energy production, and stem cell properties. This multifaceted role makes CD98hc one of the critical regulators of tumor growth, therapy resistance, and metastases. Indeed, the high expression levels of CD98hc were confirmed in various tumor tissues, including head and neck squamous cell carcinoma, glioblastoma, colon adenocarcinoma, pancreatic ductal adenocarcinoma, and others. A high expression of CD98hc has been linked to clinical prognosis and response to chemo- and radiotherapy in several types of cancer. In this mini-review, we discuss the physiological functions of CD98hc, its role in regulating tumor stemness, metastases, and therapy resistance, and the clinical significance of CD98hc as a tumor marker and therapeutic target.

Immunolocalization of Cytoplasmic ER in ER-negative Breast Carcinoma as a Potent Favorable Prognostic Predictor

It is known that estrogen receptor (ER) has extranuclear signaling functions in addition to classical genomic pathway, and estrogenic actions have been reported in ER-negative breast carcinoma cells. However, significance of cytoplasmic-ER immunoreactivity has not been reported in ER-negative breast carcinoma tissues. We immunolocalized cytoplasmic ER in 155 ER-negative breast carcinoma tissues and evaluated its clinicopathological significance including the prognosis. As a comparative cohort set, we also used 142 ER-positive breast carcinomas. Cytoplasmic-ER immunoreactivity was detected in the carcinoma cells, but not in the non-neoplastic mammary epithelium. Cytoplasmic-ER immunoreactivity was positive in the 35 out of 155 (23%) ER-negative breast carcinoma cases, whereas it was detected only in 2 out of 142 (1.4%) ER-positive cases. Cytoplasmic ER status was positively associated with cytoplasmic-PR status, but inversely associated with Ki67 labeling index or distant free-relapse survival rate. Moreover, cytoplasmic-ER status turned out to be an independent good prognostic factor for both distant relapse-free survival and breast cancer specific survival. These findings suggested that cytoplasmic ER plays important roles in the ER-negative breast carcinoma, and cytoplasmic ER is a potent good prognostic factor. Among the ER-negative breast cancer patients, clinical benefit of chemotherapy may be limited in the cytoplasmic-ER positive cases.

Potential Therapies Targeting the Metabolic Reprogramming of Diabetes-Associated Breast Cancer

In recent years, diabetes-associated breast cancer has become a significant clinical challenge. Diabetes is not only a risk factor for breast cancer but also worsens its prognosis. Patients with diabetes usually show hyperglycemia and hyperinsulinemia, which are accompanied by different glucose, protein, and lipid metabolism disorders. Metabolic abnormalities observed in diabetes can induce the occurrence and development of breast cancer. The changes in substrate availability and hormone environment not only create a favorable metabolic environment for tumorigenesis but also induce metabolic reprogramming events required for breast cancer cell transformation. Metabolic reprogramming is the basis for the development, swift proliferation, and survival of cancer cells. Metabolism must also be reprogrammed to support the energy requirements of the biosynthetic processes in cancer cells. In addition, metabolic reprogramming is essential to enable cancer cells to overcome apoptosis signals and promote invasion and metastasis. This review aims to describe the major metabolic changes in diabetes and outline how cancer cells can use cellular metabolic changes to drive abnormal growth and proliferation. We will specifically examine the mechanism of metabolic reprogramming by which diabetes may promote the development of breast cancer, focusing on the role of glucose metabolism, amino acid metabolism, and lipid metabolism in this process and potential therapeutic targets. Although diabetes-associated breast cancer has always been a common health problem, research focused on finding treatments suitable for the specific needs of patients with concurrent conditions is still limited. Most studies are still currently in the pre-clinical stage and mainly focus on reprogramming the glucose metabolism. More research targeting the amino acid and lipid metabolism is needed.

CircARID1A binds to IGF2BP3 in gastric cancer and promotes cancer proliferation by forming a circARID1A-IGF2BP3-SLC7A5 RNA–protein ternary complex

Background

Gastric cancer (GC) is one of the most common malignant tumors in China. Circular RNAs (circRNAs) are novel non-coding RNAs with important regulatory roles in cancer progression. IGF2BP3 has been found to play oncogenic roles in various cancers including GC, while the exact mechanism of IGF2BP3 is largely unknown.

Methods

The expression of IGF2BP3 in GC was evaluated by Western Blot and bioinformatics analysis. CircRNA expression profiles were screened via IGF2BP3 RIP-seq in GC. Sanger sequencing, RNase R digestion, nucleo-plasmic separation and RNA-FISH assays were used to detect the existence and expression of circARID1A. RNA ISH assay was employed to test the expression of circARID1A in paraffin-embedded GC tissues. Moreover, the function of circARID1A on cellular proliferation was assessed by CCK-8, plate colony formation, EdU assays and GC xenograft mouse model in vivo. Furthermore, the location or binding of circARID1A, IGF2BP3 protein and SLC7A5 in GC was evaluated by RNA-FISH/IF or RNA pull-down assays.

Results

We identified a novel circRNA, circARID1A, that can bind to IGF2BP3 protein. CircARID1A was significantly upregulated in GC tissues compared with noncancerous tissues and positively correlated with tumor length, tumor volume, and TNM stage. CircARID1A knockdown inhibited the proliferation of GC cells in vitro and in vivo and circARID1A played an important role in the oncogenic function of IGF2BP3. Mechanistically, circARID1A served as a scaffold to facilitate the interaction between IGF2BP3 and SLC7A5 mRNA, finally increasing SLC7A5 mRNA stability. Additionally, circARID1A was able to directly bind SLC7A5 mRNA through complementary base-pairing and then formed the circARID1A-IGF2BP3-SLC7A5 RNA–protein ternary complex and promoted the proliferation of GC via regulating AKT/mTOR pathway.

Conclusions

Altogether, our data suggest that circARID1A is involved in the function of IGF2BP3 and GC proliferation, and the circARID1A-IGF2BP3-SLC7A5 axis has the potential to serve as a novel therapeutic target for GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02466-3.

Contribution of LAT1-4F2hc in Urological Cancers via Toll-like Receptor and Other Vital Pathways

Simple Summary

LAT1-4F2hc complex is an important amino acid transporter. It mainly transports specific amino acids through the cell membrane, provides nutrition for cells, and participates in a variety of metabolic pathways. LAT1 plays a role in transporting essential amino acids including leucine, which regulates the mTOR signaling pathway. However, the importance of SLCs is still not well known in the field of urological cancer. Therefore, the purpose of this review is to report the role of the LAT1-4F2hc complex in urological cancers, as well as their clinical significance and application. Moreover, the inhibitor of LAT1-4F2hc complex is a promising direction as a targeted therapy to improve the treatment and prognosis of urological cancers.

Abstract

Tumor cells are known for their ability to proliferate. Nutrients are essential for rapidly growing tumor cells. In particular, essential amino acids are essential for tumor cell growth. Tumor cell growth nutrition requires the regulation of membrane transport proteins. Nutritional processes require amino acid uptake across the cell membrane. Leucine, one of the essential amino acids, has recently been found to be closely associated with cancer, which activate mTOR signaling pathway. The transport of leucine into cells requires an L-type amino acid transporter protein 1, LAT1 (SLC7A5), which requires the 4F2 cell surface antigen heavy chain (4F2hc, SLC3A2) to form a heterodimeric amino acid transporter protein complex. Recent evidence identified 4F2hc as a specific downstream target of the androgen receptor splice variant 7 (AR-V7). We stressed the importance of the LAT1-4F2hc complex as a diagnostic and therapeutic target in urological cancers in this review, which covered the recent achievements in research on the involvement of the LAT1-4F2hc complex in urinary system tumors. In addition, JPH203, which is a selective LAT1 inhibitor, has shown excellent inhibitory effects on the proliferation in a variety of tumor cells. The current phase I clinical trials of JPH203 in patients with biliary tract cancer have also achieved good results, which is the future research direction for LAT1 targeted therapy drugs.

Prolactin: The Third Hormone in Breast Cancer

Prolactin coordinates with the ovarian steroids to orchestrate mammary development and lactation, culminating in nourishment and an increasingly appreciated array of other benefits for neonates. Its central activities in mammary epithelial growth and differentiation suggest that it plays a role(s) in breast cancer, but it has been challenging to identify its contributions, essential for incorporation into prevention and treatment approaches. Large prospective epidemiologic studies have linked higher prolactin exposure to increased risk, particularly for ER+ breast cancer in postmenopausal women. However, it has been more difficult to determine its actions and clinical consequences in established tumors. Here we review experimental data implicating multiple mechanisms by which prolactin may increase the risk of breast cancer. We then consider the evidence for role(s) of prolactin and its downstream signaling cascades in disease progression and treatment responses, and discuss how new approaches are beginning to illuminate the biology behind the seemingly conflicting epidemiologic and experimental studies of prolactin actions across diverse breast cancers.