Regulatory mechanism and functional analysis of S100A9 in acute promyelocytic leukemia cells

S100A8 and S100A9 in Hematologic Malignancies: From Development to Therapy

S100A8 and S100A9 are multifunctional proteins that can initiate various signaling pathways and modulate cell function both inside and outside immune cells, depending on their receptors, mediators, and molecular environment. They have been reported as dysregulated genes and proteins in a wide range of cancers, including hematologic malignancies, from diagnosis to response to therapy. The role of S100A8 and S100A9 in hematologic malignancies is highlighted due to their ability to work together or as antagonists to modify cell phenotype, including viability, differentiation, chemosensitivity, trafficking, and transcription strategies, which can lead to an oncogenic phase or reduced symptoms. In this review article, we discuss the critical roles of S100A8, S100A9, and calprotectin (heterodimer or heterotetramer forms of S100A8 and S100A9) in forming and promoting the malignant bone marrow microenvironment. We also focus on their potential roles as biomarkers and therapeutic targets in various stages of hematologic malignancies from diagnosis to treatment.

S100A8 and S100A9 in Cancer

S100A8 and S100A9 are Ca²⁺ binding proteins that belong to the S100 family. Primarily expressed in neutrophils and monocytes, S100A8 and S100A9 play critical roles in modulating various inflammatory responses and inflammation-associated diseases. Forming a common heterodimer structure S100A8/A9, S100A8 and S100A9 are widely reported to participate in multiple signaling pathways in tumor cells. Meanwhile, S100A8/A9, S100A8, and S100A9, mainly as promoters, contribute to tumor development, growth and metastasis by interfering with tumor metabolism and the microenvironment. In recent years, the potential of S100A8/A9, S100A9, and S100A8 as tumor diagnostic or prognostic biomarkers has also been demonstrated. In addition, an increasing number of potential therapies targeting S100A8/A9 and related signaling pathways have emerged. In this review, we will first expound on the characteristics of S100A8/A9, S100A9, and S100A8 in-depth, focus on their interactions with tumor cells and microenvironments, and then discuss their clinical applications as biomarkers and therapeutic targets. We also highlight current limitations and look into the future of S100A8/A9 targeted anti-cancer therapy.

Intracellular calprotectin (S100A8/A9) facilitates DNA damage responses and promotes apoptosis in head and neck squamous cell carcinoma

OBJECTIVES

In head and neck squamous cell carcinoma (HNSCC), poor prognosis and low survival rates are associated with downregulated calprotectin. Calprotectin (S100A8/A9) inhibits cancer cell migration and invasion and facilitates G2/M cell cycle arrest. We investigated whether S100A8/A9 regulates DNA damage responses (DDR) and apoptosis in HNSCC after chemoradiation.

MATERIALS AND METHODS

Human HNSCC cases in TCGA were analyzed for relationships between S100A8/A9 and expression of apoptosis-related genes. Next, S100A8/A9-expressing and non-expressing carcinoma lines (two different lineages) were exposed to genotoxic agents and assessed for 53BP1 and γH2AX expression and percent of viable/dead cells. Finally, S100A8/A9-wild-type and S100A8/A9null C57BL/6j mice were treated with 4-NQO to induce oral dysplastic and carcinomatous lesions, which were compared for levels of 53BP1.

RESULTS

In S100A8/A9-high HNSCC tumors, apoptosis-related caspase family member genes were upregulated, whereas genes limiting apoptosis were significantly downregulated based on TCGA analyses. After X-irradiation or camptothecin treatment, S100A8/A9-expressing carcinoma cells (i.e., TR146 and KB-S100A8/A9) showed significantly higher 53BP1 and γH2AX expression, DNA fragmentation, proportions of dead cells, and greater sensitivity to cisplatin than wild-type KB or TR146-S100A8/A9-KD cells. Interestingly, KB-S100A8/A9Δ113-114 cells showed similar 53BP1 and γH2AX levels to S100A8/A9-negative KB and KB-EGFP cells. After 4-NQO treatment, 53BP1 expression in oral lesions was significantly greater in calprotectin+/+ than S100A8/A9null mice.

CONCLUSIONS

In HNSCC cells, intracellular calprotectin is strongly suggested to potentiate DDR and promote apoptosis in response to genotoxic agents. Hence, patients with S100A8/A9-high HNSCC may encounter more favorable outcomes because more tumor cells enter apoptosis with increased sensitivity to chemoradiation therapy.

Profile for mRNA transcript abundances in the pig endometrium where inflammation was induced by Escherichia coli

Uterine inflammation is a common reproductive disorder in domestic animals, leading to disturbances in many reproductive processes and economic losses. More information on inflammatory pathways, however, is needed to understand mechanisms of uterine inflammation. The aim of the study was to investigate transcriptomic profiles of the pig endometrium affected by inflammation. On day 3 of the estrous cycle (day 0 = initial day of study), saline or Escherichia coli suspension were injected into uterine horns. In endometrial tissues collected 8 days later, microarray analysis results indicated there were 189 differentially abundant mRNA transcripts (DEGs, 95 in relatively greater and 94 in lesser abundance) after saline injections compared with samples where there was severe acute inflammation. Relative abundance of mRNA transcripts for proteins assigned to inflammatory response, movement of phagocytes, quantity of phagocytes, leukocyte migration and adhesion of immune cells and many other functions related to inflammation were different in the Escherichia coli-treated endometrium than in samples from gilts treated with saline. Among others, S100A9, SLC11A1, CCL15, CCL3L3, CCR1, CD48, CD163, THBS1, KIT, ITGB3, JAK3 and NFKB2 mRNA transcripts were in relatively greater abundance and there were those in relatively lesser abundance including IL24, FGG, SST, CXCL16 and CREB. In this study, for the first time, there was detection of alterations in the transcriptome of the inflamed pig endometrium which may be an important finding for maintaining uterine homeostasis and functions. Results form the basis for future studies focusing on regulation of uterine inflammation in animals and women.

S100A8 and S100A9, both transcriptionally regulated by PU.1, promote epithelial-mesenchymal transformation (EMT) and invasive growth of dermal keratinocytes during scar formation post burn

S100 calcium-binding protein A8 (S100A8) and S100A9 are small molecular weight calcium-binding regulatory proteins that have been involved in multiple chronic inflammatory diseases. However, the role of S100A8 and S100A9 in keratinocytes in wounded skin and how they are regulated during this process are still unclear. Here, we found that S100A8 and S100A9 were both upregulated in burn-wounded skins in vivo and thermal-stimulated epidermal keratinocytes in vitro, accompanied by increased levels of epithelial-mesenchymal transition (EMT). Then, we demonstrated that upregulation of S100A8 and S100A9 alone or together enhanced characteristics of EMT in normal keratinocytes, manifested by excessive proliferation rate, abnormal ability of cell invasion, and high expression levels of EMT marker proteins. The transcription factor PU box-binding protein (PU.1) bound to the promoter regions and transcriptionally promoted the expression of S100A8 and S100A9 both in the human and mice, and it had strong positive correlations with both S100A8 and S100A9 protein levels in burned skin in vivo. Moreover, PU.1 positively regulated expression of S100A8 and S100A9 in a dose-dependent manner, and enhanced EMT of keratinocytes in vitro. Finally, through the burn mouse model, we found that PU.1-/- mice displayed a lower ability of scar formation, manifested by smaller scar volume, thickness, and collagen content, which could be enhanced by S100A8 and S100A9. In conclusion, PU.1 transcriptionally promotes expression of S100A8 and S100A9, thus positively regulating epithelial-mesenchymal transformation (EMT) and invasive growth of dermal keratinocytes during scar formation post burn.

Pathogenic Roles of S100A8 and S100A9 Proteins in Acute Myeloid and Lymphoid Leukemia: Clinical and Therapeutic Impacts

Deregulations of the expression of the S100A8 and S100A9 genes and/or proteins, as well as changes in their plasma levels or their levels of secretion in the bone marrow microenvironment, are frequently observed in acute myeloblastic leukemias (AML) and acute lymphoblastic leukemias (ALL). These deregulations impact the prognosis of patients through various mechanisms of cellular or extracellular regulation of the viability of leukemic cells. In particular, S100A8 and S100A9 in monomeric, homodimeric, or heterodimeric forms are able to modulate the survival and the sensitivity to chemotherapy of leukemic clones through their action on the regulation of intracellular calcium, on oxidative stress, on the activation of apoptosis, and thanks to their implications, on cell death regulation by autophagy and pyroptosis. Moreover, biologic effects of S100A8/9 via both TLR4 and RAGE on hematopoietic stem cells contribute to the selection and expansion of leukemic clones by excretion of proinflammatory cytokines and/or immune regulation. Hence, the therapeutic targeting of S100A8 and S100A9 appears to be a promising way to improve treatment efficiency in acute leukemias.

S100A3 a partner protein regulating the stability/activity of RARα and PML-RARα in cellular models of breast/lung cancer and acute myeloid leukemia

All trans-retinoic acid (ATRA) is used in the treatment of acute promyelocytic leukemia (APL) and it is a promising agent also in solid tumors. The pharmacological activity of ATRA is mediated by the ligand-activated RAR and RXR transcription factors. In the present study, we define the basal and ATRA dependent RARα interactome in a RARα-overexpressing breast cancer cellular model, identifying 28 nuclear proteins. We focus our attention on the S100A3 calcium-binding protein, which interacts with RARα constitutively. In ATRA-sensitive breast cancer cells, S100A3 binds to RARα in basal conditions and binding is reduced by the retinoid. The interaction of S100A3 with RARα is direct and in lung cancer, APL and acute-myeloid-leukemia (AML) cells. In APL, S100A3 interacts not only with RARα, but also with PML-RARα. The interaction surface maps to the RARα ligand-binding domain, where the I396 residue plays a crucial role. Binding of S100A3 to RARα/PML-RARα controls the constitutive and ATRA-dependent degradation of these receptors. S100A3 knockdown decreases the amounts of RARα in breast- and lung cancer cells, inducing resistance to ATRA-dependent anti-proliferative/differentiating effects. Conversely, S100A3 knockdown in PML-RARα⁺ APL and PML-RARα^- AML cells reduces the amounts of RARα/PML-RARα and increases basal and ATRA-induced differentiation. In this cellular context, opposite effects on RARα/PML-RARα levels and ATRA-induced differentiation are observed upon S100A3 overexpression. Our results provide new insights into the molecular mechanisms controlling RARα activity and have practical implications, as S100A3 represents a novel target for rational drug combinations aimed at potentiating the activity of ATRA.

S100 Proteins in Acute Myeloid Leukemia

The S100 protein family contains 20 functionally expressed members, which are commonly dysregulated in cancer. Their wide range of functions includes cell proliferation, cell differentiation, regulation of transcription factors, inflammation, chemotaxis, and angiogenesis. S100 proteins have in several types of cancer proven to be biomarkers for disease progression and prognosis. Acute myeloid leukemia (AML) is a highly heterogeneous and aggressive disease in which immature myeloblasts replace normal hematopoietic cells in the bone marrow. This review focuses on the S100 protein family members, which commonly are dysregulated in AML, and on the consequences of their dysregulation in the disorder. Like in other cancers, it appears as if S100 proteins are potential biomarkers for leukemogenesis. Furthermore, several S100 members seem to be involved in maintaining the leukemic phenotype. For these reasons, specific S100 proteins might serve as prognostic biomarkers, especially in the patient subset with intermediate/undetermined risk, and as potential targets for patient-adjusted therapy. Because the question of the most suitable candidate S100 biomarkers in AML still is under discussion, because particular AML subgroups lead to specific S100 signatures, and because downstream effects and the significance of co-expression of potential S100 binding partners in AML are not fully elucidated yet, we conclude that a panel of S100 proteins will probably be best suited for prognostic purposes.

The role of calgranulin B gene on the biological behavior of squamous cervical cancer in vitro and in vivo

Objective

The objective of the study was to explore the role of calgranulin B gene on the biological behavior of squamous cervical cancer.

Methods

Differential transcription in calgranulin B gene between human papillomavirus (HPV)-positive and negative cervical cancer groups was identified, and the relationship between calgranulin B gene and matrix metalloproteinase (MMP) genes were explored using The Cancer Genome Atlas database. Subsequently, the role of calgranulin B on the cell proliferation, apoptosis, invasion and migration was investigated, through overexpression and/or underexpression of calgranulin B in cervical cancer cells. In addition, the effect of calgranulin B on the growth of the cervical cancer was studied via constructing xenograft model in BALB/c nude mice that either overexpressed or underexpressed calgranulin B.

Results

Calgranulin B gene transcription in cervical cancer was highly correlated with the high-risk HPV-16 and HPV-45. In addition, overexpression of calgranulin B increased cell proliferation, invasion and migration, whereas it did not significantly affect cell apoptosis. This effect was also confirmed by calgranulin B knockdown assay. Additionally, we found that the transcription of calgranulin B gene was negatively correlated with MMP15 and MMP24 genes, but positively associated with MMP25 genes in cervical cancer. Furthermore, calgranulin B significantly promoted the growth of cervical cancer in vivo.

Conclusion

Calgranulin B promotes cell proliferation, migration and invasion of squamous cervical cancer, possibly via regulation of MMPs. Whether there are synergistic actions between calgranulin B and HPV-16/HPV-45 infection on the squamous cervical carcinogenesis or progression need further study.

Calprotectin and the Initiation and Progression of Head and Neck Cancer

Calprotectin (S100A8/A9), a heterodimeric complex of calcium-binding proteins S100A8 and S100A9, is encoded by genes mapping to the chromosomal locus 1q21.3 of the epidermal differentiation complex. Whereas extracellular calprotectin shows proinflammatory and antimicrobial properties by signaling through RAGE and TLR4, intracytoplasmic S100A8/A9 appears to be important for cellular development, maintenance, and survival. S100A8/A9 is constitutively expressed in myeloid cells and the stratified mucosal epithelia lining the oropharyngeal and genitourinary mucosae. While upregulated in adenocarcinomas and other cancers, calprotectin mRNA and protein levels decline in head and neck squamous cell carcinoma (HNSCC). S100A8/A9 is also lost during head and neck preneoplasia (dysplasia). Calprotectin decrease does not correlate with the clinical stage (TNM) of HNSCC. When expressed in carcinoma cells, S100A8/A9 downregulates matrix metalloproteinase 2 expression and inhibits invasion and migration in vitro. S100A8/A9 regulates cell cycle progression and decelerates cancer cell proliferation by arresting at the G2/M checkpoint in a protein phosphatase 2α-dependent manner. In HNSCC, S100A8 and S100A9 coregulate with gene networks controlling cellular development and differentiation, cell-to-cell signaling, and cell morphology, while S100A8/A9 appears to downregulate expression of invasion- and tumorigenesis-associated genes. Indeed, tumor formation capacity is attenuated in S100A8/A9-expressing carcinoma cells in vivo. Hence, intracellular calprotectin appears to function as a tumor suppressor in head and neck carcinogenesis. When compared with S100A8/A9-low HNSCC based on analysis of TCGA, S100A8/A9-high HNSCC shows significant upregulation of apoptosis-related genes, including multiple caspases. Accordingly, S100A8/A9 facilitates DNA damage responses in HNSCC, promotes apoptotic cell death, and confers sensitivity to cisplatin and X-radiation in vitro. In the tumor milieu, loss of S100A8/A9 strongly associates with poor squamous differentiation and higher tumor grading, EGFR upregulation, increased DNA methylation, and, finally, poorer overall survival for patients with HNSCC. Hence, intracellular calprotectin shows a multifaceted protective role against the development of HNSCC.