Overexpression of CD44 Standard Isoform Upregulates HIF-1α Signaling in Hypoxic Breast Cancer Cells

Extracellular vesicles and cancer stem cells: a deadly duo in tumor progression

The global incidence of cancer is increasing, with estimates suggesting that there will be 26 million new cases and 17 million deaths per year by 2030. Cancer stem cells (CSCs) and extracellular vesicles (EVs) are key to the resistance and advancement of cancer. They play a crucial role in tumor dynamics and resistance to therapy. CSCs, initially discovered in acute myeloid leukemia, are well-known for their involvement in tumor initiation, progression, and relapse, mostly because of their distinct characteristics, such as resistance to drugs and the ability to self-renew. EVs, which include exosomes, microvesicles, and apoptotic bodies, play a vital role in facilitating communication between cells within the tumor microenvironment (TME). They have a significant impact on cellular behaviors and contribute to genetic and epigenetic changes. This paper analyzes the mutually beneficial association between CSCs and EVs, emphasizing their role in promoting tumor spread and developing resistance mechanisms. This review aims to investigate the interaction between these entities in order to discover new approaches for attacking the complex machinery of cancer cells. It highlights the significance of CSCs and EVs as crucial targets in the advancement of novel cancer treatments, which helps stimulate additional research, promote progress in ideas for cancer treatment, and provide renewed optimism in the effort to reduce the burden of cancer.

Disorders of cancer metabolism: The therapeutic potential of cannabinoids

Abnormal energy metabolism, as one of the important hallmarks of cancer, was induced by multiple carcinogenic factors and tumor-specific microenvironments. It comprises aerobic glycolysis, de novo lipid biosynthesis, and glutamine-dependent anaplerosis. Considering that metabolic reprogramming provides various nutrients for tumor survival and development, it has been considered a potential target for cancer therapy. Cannabinoids have been shown to exhibit a variety of anticancer activities by unclear mechanisms. This paper first reviews the recent progress of related signaling pathways (reactive oxygen species (ROS), AMP-activated protein kinase (AMPK), mitogen-activated protein kinases (MAPK), phosphoinositide 3-kinase (PI3K), hypoxia-inducible factor-1alpha (HIF-1α), and p53) mediating the reprogramming of cancer metabolism (including glucose metabolism, lipid metabolism, and amino acid metabolism). Then we comprehensively explore the latest discoveries and possible mechanisms of the anticancer effects of cannabinoids through the regulation of the above-mentioned related signaling pathways, to provide new targets and insights for cancer prevention and treatment.

CD44 Promotes Breast Cancer Metastasis through AKT-Mediated Downregulation of Nuclear FOXA2

The primary cause of breast cancer mortality is the metastatic invasion of cancerous stem cells (CSC). Cluster of differentiation 44 (CD44) is a well-known CSC marker in various cancers, as well as a key role player in metastasis and relapse of breast cancer. CD44 is a cell-membrane embedded protein, and it interacts with different proteins to regulate cancer cell behavior. Transcription factor forkhead box protein A2 (FOXA2) acts as an important regulator in multiple cancers, including breast cancer. However, the biological significance of CD44-FOXA2 association in breast cancer metastasis remains unclear. Herein, we observed that CD44 expression was higher in metastatic lymph nodes compared to primary tumors using a flow cytometric analysis. CD44 overexpression in breast cancer cell lines significantly promoted cell migration and invasion abilities, whereas the opposite effects occurred upon the knockdown of CD44. The stem cell array analysis revealed that FOXA2 expression was upregulated in CD44 knockdown cells. However, the knockdown of FOXA2 in CD44 knockdown cells reversed the effects on cell migration and invasion. Furthermore, we found that CD44 mediated FOXA2 localization in breast cancer cells through the AKT pathway. Moreover, the immunofluorescence assay demonstrated that AKT inhibitor wortmannin and AKT activator SC79 treatment in breast cancer cells impacted FOXA2 localization. Collectively, this study highlights that CD44 promotes breast cancer metastasis by downregulating nuclear FOXA2.

Differential expression of checkpoint markers in the normoxic and hypoxic microenvironment of glioblastomas

Glioblastoma is the most common primary malignant brain tumor in adults with an overall survival of only 14.6 months. Hypoxia is known to play a role in tumor aggressiveness but the influence of hypoxia on the immune microenvironment is not fully understood. The aim of this study was to investigate the expression of immune-related proteins in normoxic and hypoxic tumor areas by digital spatial profiling. Tissue samples from 10 glioblastomas were stained with a panel of 40 antibodies conjugated to photo-cleavable oligonucleotides. The free oligo-tags from normoxic and hypoxic areas were hybridized to barcodes for digital counting. Differential expression patterns were validated by Ivy Glioblastoma Atlas Project (GAP) data and an independent patient cohort. We found that CD44, Beta-catenin and B7-H3 were upregulated in hypoxia, whereas VISTA, CD56, KI-67, CD68 and CD11c were downregulated. PD-L1 and PD-1 were not affected by hypoxia. Focusing on the checkpoint-related markers CD44, B7-H3 and VISTA, our findings for CD44 and VISTA could be confirmed with Ivy GAP RNA sequencing data. Immunohistochemical staining and digital quantification of CD44, B7-H3 and VISTA in an independent cohort confirmed our findings for all three markers. Additional stainings revealed fewer T cells and high but equal amounts of tumor-associated microglia and macrophages in both hypoxic and normoxic regions. In conclusion, we found that CD44 and B7-H3 were upregulated in areas with hypoxia whereas VISTA was downregulated together with the presence of fewer T cells. This heterogeneous expression should be taken into consideration when developing novel therapeutic strategies.

HIF-1α in Osteoarthritis: From Pathogenesis to Therapeutic Implications

Osteoarthritis is a common age-related joint degenerative disease. Pain, swelling, brief morning stiffness, and functional limitations are its main characteristics. There are still no well-established strategies to cure osteoarthritis. Therefore, better clarification of mechanisms associated with the onset and progression of osteoarthritis is critical to provide a theoretical basis for the establishment of novel preventive and therapeutic strategies. Chondrocytes exist in a hypoxic environment, and HIF-1α plays a vital role in regulating hypoxic response. HIF-1α responds to cellular oxygenation decreases in tissue regulating survival and growth arrest of chondrocytes. The activation of HIF-1α could regulate autophagy and apoptosis of chondrocytes, decrease inflammatory cytokine synthesis, and regulate the chondrocyte extracellular matrix environment. Moreover, it could maintain the chondrogenic phenotype that regulates glycolysis and the mitochondrial function of osteoarthritis, resulting in a denser collagen matrix that delays cartilage degradation. Thus, HIF-1α is likely to be a crucial therapeutic target for osteoarthritis via regulating chondrocyte inflammation and metabolism. In this review, we summarize the mechanism of hypoxia in the pathogenic mechanisms of osteoarthritis, and focus on a series of therapeutic treatments targeting HIF-1α for osteoarthritis. Further clarification of the regulatory mechanisms of HIF-1α in osteoarthritis may provide more useful clues to developing novel osteoarthritis treatment strategies.

CD44 promotes hepatocellular carcinoma progression via upregulation of YAP

Hepatocellular carcinoma (HCC) is a common malignancy in human. CD44 is a transmembrane glycoprotein which is frequently overexpressed in cancer of various origins. The function and mechanism of CD44 in HCC remains elusive. In this study, we reported that CD44 was overexpressed in HCC to promote the proliferation and migration of HCC cells via oncogenic YAP, which is the key downstream regulator in Hippo pathway. These findings suggest that CD44-YAP is a probable important axis in pathogenesis of HCC, providing an insight in to HCC pathogenesis as well as potential targets for the intervention of HCC.

CD44 in Ovarian Cancer Progression and Therapy Resistance-A Critical Role for STAT3

Despite significant progress in cancer therapy over the last decades, ovarian cancer remains the most lethal gynecologic malignancy worldwide with the five-year overall survival rate less than 30% due to frequent disease recurrence and chemoresistance. CD44 is a non-kinase transmembrane receptor that has been linked to cancer metastatic progression, cancer stem cell maintenance, and chemoresistance development via multiple mechanisms across many cancers, including ovarian, and represents a promising therapeutic target for ovarian cancer treatment. Moreover, CD44-mediated signaling interacts with other well-known pro-tumorigenic pathways and oncogenes during cancer development, such as signal transducer and activator of transcription 3 (STAT3). Given that both CD44 and STAT3 are strongly implicated in the metastatic progression and chemoresistance of ovarian tumors, this review summarizes currently available evidence about functional crosstalk between CD44 and STAT3 in human malignancies with an emphasis on ovarian cancer. In addition to the role of tumor cell-intrinsic CD44 and STAT3 interaction in driving cancer progression and metastasis, we discuss how CD44 and STAT3 support the pro-tumorigenic tumor microenvironment and promote tumor angiogenesis, immunosuppression, and cancer metabolic reprogramming in favor of cancer progression. Finally, we review the current state of therapeutic CD44 targeting and propose superior treatment possibilities for ovarian cancer.

The novel interplay between CD44 standard isoform and the caspase-1/IL1B pathway to induce hepatocellular carcinoma progression

Accumulating data indicate caspase-1 (CASP1), one of the inflammatory caspases, promotes hepatocellular carcinoma (HCC) progression in tumor proliferation, invasion, EMT phenotype and sorafenib resistance. However, the molecular basis of regulating caspase-1 expression and caspase-1/IL1B (interleukin-1β) pathway in HCC remains unclear. Here, we demonstrated the novel interplay between caspase-1/IL1B activation and cluster differentiation 44 standard isoform (CD44s) in HCC. In this study, we observed that CD44s is responsible for caspase-1/IL1B activation both in HCC tissues and five HCC cell lines. In normoxia conditions, CD44s knockdown repressed the activation of caspase-1/IL1B via stimulating AMPK-mediated autophagy. Moreover, our data suggested that p62-induced autophagic degradation of caspase-1 accounted for caspase-1/IL1B inactivation in CD44s deficient cells. Administration of recombinant human IL1B could rescue impaired proliferation, invasion, and EMT phenotype in CD44s deficient HCC cells. Lastly, hypoxia-mediated caspase-1/IL1B overexpression could be abolished by CD44s downregulation through decreasing HIF1A and enhancing autophagic activity. Overall, targeting CD44s is a novel inhibitory mechanism of caspase-1/IL1B expression, both in normoxia and hypoxia conditions.

The role of CD44 in pathological angiogenesis

Angiogenesis is required for normal development and occurs as a pathological step in a variety of disease settings, such as cancer, ocular diseases, and ischemia. Recent studies have revealed the role of CD44, a widely expressed cell surface adhesion molecule, in promoting pathological angiogenesis and the development of its associated diseases through its regulation of diverse function of endothelial cells, such as proliferation, migration, adhesion, invasion, and communication with the microenvironment. Conversely, the absence of CD44 expression or inhibition of its function impairs pathological angiogenesis and disease progression. Here, we summarize the current understanding of the roles of CD44 in pathological angiogenesis and the underlying cellular and molecular mechanisms.

Tumour Regression via Integrative Regulation of Neurological, Inflammatory, and Hypoxic Tumour Microenvironment

Changing trends in anticancer research have altered the treatment paradigm to the extent that it is difficult to investigate any anticancer drugs without mentioning immunotherapy. Thus, we are finally contemplating tumour regression using magic bullets known as immunotherapy drugs. This review explores the possible options and pitfalls in tumour regression by first elucidating the features of cancer and the importance of tumour microenvironments. Next, we evaluated the trends of anticancer therapeutics regulating tumour microenvironment. Finally, we introduced the concept of tumour regression and various targets of tumour microenvironment, which can be used in combination with current immunotherapy for tumour regression. In particular, we emphasize the importance of regulating the neurological manifestations of tumour microenvironment (N) in addition to inflammation (I) and hypoxia (H) in cancer.

Human steroid sulfatase enhances aerobic glycolysis through induction of HIF1α and glycolytic enzymes

Human steroid sulfatase (STS) has been linked with poor prognosis in steroid-associated tumors and represents an important clinical target in cancers, yet the mechanism of STS-induced carcinogenesis remains unclear. To correlate STS with cancer metabolism, we determined the effects of STS on aerobic glycolysis. STS overexpression increased cellular levels of lactic acid, the final product of aerobic glycolysis. Moreover, STS suppressed the oxygen consumption rate (OCR), which represents mitochondrial respiration. Inhibition of STS by the specific inhibitor STX064 recovered STS-induced OCR repression and lactic acid over-production. DHEA, but not DHEA-S, suppressed the OCR level and enhanced lactic acid production. To understand the molecular mechanism of STS-induced cancer metabolism, we measured the expression of glycolytic enzymes hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2), which was highly upregulated by STS and DHEA at both protein and mRNA levels. HIF1α is a key mediator of aerobic glycolysis, and STS enhanced HIF1α promoter activity, mRNA expression, and protein expression. Down-regulation of HIF1α by siRNA suppressed the HK2 and PKM2 expression induced by both STS and DHEA. HIF1α siRNA also recovered the OCR repression and lactic acid over-production induced by both STS and DHEA. To explore the mechanism in vivo, we produced transgenic mice overexpressing STS and found that STS expression was particularly enhanced in the lung. Consistent with our in vitro results, the expression of HIF1α, HK2, and PKM2 was also increased in mouse lung tissues. In conclusion, we suggest that STS may induce aerobic glycolysis through enhancing HIF1α expression.

Hypoxia as a signal for prison breakout in cancer

PURPOSE OF REVIEW

We discuss recent discoveries in hypoxic cellular pathophysiology and explore the interplay between hypoxic malignant cells and other stromal elements. This review will provide an update on the effects of hypoxia on cancer outcomes and therapeutic resistance.

RECENT FINDINGS

Hypoxia has been discovered to be a key driver for tumor progression, both because of impacts on tumor cells and separately on the wider tumor microenvironment. The latter effects occur via epithelial mesenchymal transition, autophagy and metabolic switching. Through epithelial mesenchymal transition, hypoxia both drives metastasis and renders key target tissues receptive to metastasis. Autophagy is a double-edged sword which requires greater understanding to ascertain when it is a threat. Metabolic switching allows tumor cells to access hypoxic survival mechanisms even under normoxic conditions.Every element of the malignant stroma contributes to hypoxia-driven progression. Exosomal transfer of molecules from hypoxic tumor cells to target stromal cell types and the importance of microRNAs in intercellular communication have emerged as key themes.Antiangiogenic resistance can be caused by hypoxia-driven vasculogenic mimicry. Beyond this, hypoxia contributes to resistance to virtually all oncological treatment modalities.

SUMMARY

Recent advances have moved us closer to being able to exploit hypoxic mechanisms to overcome hypoxia-driven progression and therapy failure.

Bardoxolone ameliorates TGF-β1-associated renal fibrosis through Nrf2/Smad7 elevation

Transforming growth factor-β (TGF-β) is a potent pathogenic factor of renal injury through the upregulation of extracellular matrix (ECM) expression and facilitation of renal fibrosis. Nuclear factor erythroid 2-like 2 (Nfe2l2; Nrf2), a master regulator of antioxidant and detoxifying systems, is mainly controlled by the binding with cytosolic protein Kelch-like ECH-associated protein 1 (Keap1) and subsequent proteasomal degradation. The protective effect of Nrf2 on renal injury has been attributed to its antioxidant role, where it aids in coping with oxidative stress-associated progression of renal disease. In this study, we investigated the effect of Nrf2 activation on ECM production and TGF-β/Smad signaling using Keap1-silenced MES-13 cells (a genetic glomerular mesangial cell model with Nrf2 overexpression). The TGF-β1-inducible expression of fibronectin and α-smooth muscle actin (α-Sma) was suppressed and Smad2/3 phosphorylation was blocked in Nrf2-high mesangial cells as compared with that in control cells. Notably, in these Nrf2-high mesangial cells, levels of TGF-β1 receptor 1 (TβR1) were substantially diminished, and the protein levels of Smad7, an inhibitor TGF-β1/Smad signaling, were increased. Nrf2-mediated Smad7 elevation and its anti-fibrotic role in Keap1-silenced cells were confirmed by studies with Nrf2-or Smad7-silencing. As a molecular link for Smad7 elevation in Nrf2-high cells, the reduction of Smad-ubiquitination-regulatory factor 1 (Smurf1), an E3 ubiquitin ligase for Smad7, was notable. Silencing of Smurf1 increased Smad7 in the control mesangial cells; however, forced expression of Smurf1 repressed Smad7 levels in Keap1-silenced cells. Additionally, we demonstrate that bardoxolone (BARD; CDDO-methyl), a pharmacological activator of Nrf2, increased Smad7 levels and attenuated TGF-β/Smad/ECM expression in MES-13. Moreover, in an aristolochic acid (AA)-mediated nephropathy mouse model, the renal expression of Nrf2 and Smad7 was elevated by BARD treatment, and AA-induced tubular necrosis and interstitial fibrosis were substantially ameliorated by BARD. Collectively, these results indicate that the Nrf2-Smad7 axis plays a key role in the protection of TGF-β-induced renal fibrosis, and further suggest a novel molecular mechanism of beneficial effect of BARD on renal disease.

Anticancer Activities of Thymus vulgaris L. in Experimental Breast Carcinoma in Vivo and in Vitro

Naturally-occurring mixtures of phytochemicals present in plant foods are proposed to possess tumor-suppressive activities. In this work, we aimed to evaluate the antitumor effects of Thymus vulgaris L. in in vivo and in vitro mammary carcinoma models. Dried T. vulgaris (as haulm) was continuously administered at two concentrations of 0.1% and 1% in the diet in a chemically-induced rat mammary carcinomas model and a syngeneic 4T1 mouse model. After autopsy, histopathological and molecular analyses of rodent mammary carcinomas were performed. In addition, in vitro evaluations using MCF-7 and MDA-MB-231 cells were carried out. In mice, T. vulgaris at both doses reduced the volume of 4T1 tumors by 85% (0.1%) and 84% (1%) compared to the control, respectively. Moreover, treated tumors showed a substantial decrease in necrosis/tumor area ratio and mitotic activity index. In the rat model, T. vulgaris (1%) decreased the tumor frequency by 53% compared to the control. Analysis of the mechanisms of anticancer action included well-described and validated diagnostic and prognostic markers that are used in both clinical approach and preclinical research. In this regard, the analyses of treated rat carcinoma cells showed a CD44 and ALDH1A1 expression decrease and Bax expression increase. Malondialdehyde (MDA) levels and VEGFR-2 expression were decreased in rat carcinomas in both the T. vulgaris treated groups. Regarding the evaluations of epigenetic changes in rat tumors, we found a decrease in the lysine methylation status of H3K4me3 in both treated groups (H3K9m3, H4K20m3, and H4K16ac were not changed); up-regulations of miR22, miR34a, and miR210 expressions (only at higher doses); and significant reductions in the methylation status of four gene promoters—ATM serin/threonine kinase, also known as the NPAT gene (ATM); Ras-association domain family 1, isoform A (RASSF1); phosphatase and tensin homolog (PTEN); and tissue inhibitor of metalloproteinase-3 (TIMP3) (the paired-like homeodomain transcription factor (PITX2) promoter was not changed). In vitro study revealed the antiproliferative and proapoptotic effects of essential oils of T. vulgaris in MCF-7 and MDA-MB-231 cells (analyses of 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS); 5-bromo-20-deoxyuridine (BrdU); cell cycle; annexin V/PI; caspase-3/7; Bcl-2; PARP; and mitochondrial membrane potential). T. vulgaris L. demonstrated significant chemopreventive and therapeutic activities against experimental breast carcinoma.