Loss of SPARC protects hematopoietic stem cells from chemotherapy toxicity by accelerating their return to quiescence. Blood. 2014;123:4054-4063. [PMID: 24833352 DOI: 10.1182/blood-2013-10-533711]

Omics Overview of the SPARC Gene in Mesothelioma

The SPARC gene plays multiple roles in extracellular matrix synthesis and cell shaping, associated with tumor cell migration, invasion, and metastasis. The SPARC gene is also involved in the epithelial-mesenchymal transition (EMT) process, which is a critical phenomenon leading to a more aggressive cancer cell phenotype. SPARC gene overexpression has shown to be associated with poor survival in the mesothelioma (MESO) cohort from the TCGA database, indicating that this gene may be a powerful prognostic factor in MESO. Its overexpression is correlated with the immunosuppressive tumor microenvironment. Here, we summarize the omics advances of the SPARC gene, including the summary of SPARC gene expression associated with prognosis in pancancer and MESO, the immunosuppressive microenvironment, and cancer cell stemness. In addition, SPARC might be targeted by microRNAs. Notably, despite the controversial functions on angiogenesis, SPARC may directly or indirectly contribute to tumor angiogenesis in MESO. In conclusion, SPARC is involved in tumor invasion, metastasis, immunosuppression, cancer cell stemness, and tumor angiogenesis, eventually impacting patient survival. Strategies targeting this gene may provide novel therapeutic approaches to the treatment of MESO.

The role of SPARC/ON in human osteosarcoma

The human osteosarcoma is a malignant tumor of the arthro-skeletal system. It has been recognized that it is the most common malignancy followed by the Ewing sarcoma or primitive neuroectodermal tumor. The prognosis is worrisome and is not preserved by the use of classical chemotherapy drugs. High rates of recurrence and metastases often accompany this malignant tumor. Chemotherapy often fails because of the onset of multidrug resistance, even though the mechanism to reach chemotherapy resistance is still intriguing and contains unclear pathways. The secreted protein acidic and rich in cysteine (SPARC) or osteonectin (ON) (SPARC/ON) has been associated with poor prognosis in several malignant neoplasms. In this mini-review, we are going to highlight the role of SPARC/ON in human osteosarcoma. Extracellular vesicles are fundamental in cell-to-cell communication. We suggest that a liquid biopsy targeting SPARC/ON may be critical to implement in the surveillance of patients with this malignant bony neoplasm.

The extracellular matrix of hematopoietic stem cell niches

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Comprehensive overview of different classes of ECM molecules in the HSC niche.

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Overview of current knowledge on role of biophysics of the HSC niche.

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Description of approaches to create artificial stem cell niches for several application.

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Importance of considering ECM in drug development and testing.

Hematopoietic stem cells (HSCs) are the life-long source of all types of blood cells. Their function is controlled by their direct microenvironment, the HSC niche in the bone marrow. Although the importance of the extracellular matrix (ECM) in the niche by orchestrating niche architecture and cellular function is widely acknowledged, it is still underexplored. In this review, we provide a comprehensive overview of the ECM in HSC niches. For this purpose, we first briefly outline HSC niche biology and then review the role of the different classes of ECM molecules in the niche one by one and how they are perceived by cells. Matrix remodeling and the emerging importance of biophysics in HSC niche function are discussed. Finally, the application of the current knowledge of ECM in the niche in form of artificial HSC niches for HSC expansion or targeted differentiation as well as drug testing is reviewed.

HMCES safeguards genome integrity and long-term self-renewal of hematopoietic stem cells during stress responses

Hematopoietic stress drives quiescent hematopoietic stem cells (HSCs) to proliferate, generating reactive oxygen species (ROS) and oxidative DNA damage including abasic sites. Such a coupling between rapid DNA replication and a burst of abasic site formation during HSC stress responses, however, presents a challenge to accurately repair abasic sites located in replication-associated single-stranded DNA. Here we show that HMCES, a novel shield of abasic sites, plays pivotal roles in overcoming this challenge upon HSC activation. While HMCES was dispensable for steady-state hematopoiesis, Hmces-deficient HSCs exhibited compromised long-term self-renewal capacity in response to hematopoietic stress such as myeloablation and transplantation. Loss of HMCES resulted in accumulation of DNA lesions due to impaired resolution of abasic sites generated by activation-induced ROS in activated HSCs and broad downregulation of DNA damage response and repair pathways. Moreover, Hmces-deficient mice died from bone marrow failure after exposure to sublethal irradiation, which also produces ROS. Notably, dysregulation of HMCES occurs frequently in acute lymphocytic leukemia (ALL) and is associated with poor clinical outcomes. Together, our findings not only highlighted HMCES as a novel genome protector in activated HSCs, but also position it as a potential selective target against ALL while sparing normal hematopoiesis.

Protein quality control through endoplasmic reticulum-associated degradation maintains haematopoietic stem cell identity and niche interactions

Stem cells need to be protected from genotoxic and proteotoxic stress to maintain a healthy pool throughout life^1–3. Little is known about the proteostasis mechanism that safeguards the stem cells. Here, we report Endoplasmic Reticulum-Associated Degradation (ERAD) as a protein quality checkpoint that controls hematopoietic stem cell (HSC)-niche interaction and determines the fate of HSC. SEL1L-HRD1 complex, the most conserved branch of ERAD⁴, is highly expressed in HSC. Deletion of Sel1l led to niche displacement of HSC, complete loss of HSC identity, and allowed highly efficient donor-HSC engraftment without irradiation. Mechanistic studies identified MPL, the master regulator of HSC identity⁵, as a bona-fide ERAD substrate that became aggregated in the ER upon ERAD deficiency. Restoration of MPL signaling with an agonist partially rescued the number and reconstitution capacity of Sel1l-deficient HSCs. Our study defines ERAD as an essential proteostasis mechanism to safeguard a healthy stem cell pool through regulating the stem cell-niche interaction.

iTRAQ-based quantitative protein expression profiling of biomarkers in childhood B-cell and T-cell acute lymphoblastic leukemia

Purpose

This study screened serum proteins to identify potential biomarkers for childhood B-cell and T-cell acute lymphoblastic leukemia (ALL).

Patients and methods

Serum collected from 20 newly diagnosed B-cell ALL, 20 T-cell ALL and 20 healthy children. The peptides from these samples were subjected to iTRAQ. Differentially expressed proteins (DEPs) were further validated by ELISA in 24 B-ALL, 24 T-ALL, and 24 healthy children.

Results

Bioinformatics analysis revealed several pathways, including atherosclerosis signaling, interleukin signaling and production in macrophages and clathrin-mediated endocytosis signaling, that were closely related to childhood T-cell ALL. Furthermore, four selected proteins, namely LRG1, S100A8, SPARC and sL-selectin, were verified by ELISA. These results were consistent with the results of the proteomics analysis.

Conclusion

Serum S100A8 may serve as new diagnostic biomarkers in childhood B-cell ALL and T-cell ALL.

The Role of the Extracellular Matrix in Cancer Stemness

As our understanding of cancer cell biology progresses, it has become clear that tumors are a heterogenous mixture of different cell populations, some of which contain so called "cancer stem cells" (CSCs). Hallmarks of CSCs include self-renewing capability, tumor-initiating capacity and chemoresistance. The extracellular matrix (ECM), a major structural component of the tumor microenvironment, is a highly dynamic structure and increasing evidence suggests that ECM proteins establish a physical and biochemical niche for CSCs. In cancer, abnormal ECM dynamics occur due to disrupted balance between ECM synthesis and secretion and altered expression of matrix-remodeling enzymes. Tumor-derived ECM is biochemically distinct in its composition and is stiffer compared to normal ECM. In this review, we will provide a brief overview of how different components of the ECM modulate CSC properties then discuss how physical, mechanical, and biochemical cues from the ECM drive cancer stemness. Given the fact that current CSC targeting therapies face many challenges, a better understanding of CSC-ECM interactions will be crucial to identify more effective therapeutic strategies to eliminate CSCs.

Attenuation of PKCδ enhances metabolic activity and promotes expansion of blood progenitors

A finely tuned balance of self‐renewal, differentiation, proliferation, and survival governs the pool size and regenerative capacity of blood‐forming hematopoietic stem and progenitor cells (HSPCs). Here, we report that protein kinase C delta (PKCδ) is a critical regulator of adult HSPC number and function that couples the proliferative and metabolic activities of HSPCs. PKCδ‐deficient mice showed a pronounced increase in HSPC numbers, increased competence in reconstituting lethally irradiated recipients, enhanced long‐term competitive advantage in serial transplantation studies, and an augmented HSPC recovery during stress. PKCδ‐deficient HSPCs also showed accelerated proliferation and reduced apoptosis, but did not exhaust in serial transplant assays or induce leukemia. Using inducible knockout and transplantation models, we further found that PKCδ acts in a hematopoietic cell‐intrinsic manner to restrict HSPC number and bone marrow regenerative function. Mechanistically, PKCδ regulates HSPC energy metabolism and coordinately governs multiple regulators within signaling pathways implicated in HSPC homeostasis. Together, these data identify PKCδ as a critical regulator of HSPC signaling and metabolism that acts to limit HSPC expansion in response to physiological and regenerative demands.

Preventing chemotherapy-induced myelosuppression by repurposing the FLT3 inhibitor quizartinib

We describe an approach to inhibit chemotherapy-induced myelosuppression. We found that short-term exposure of mice to the FLT3 inhibitor quizartinib induced the transient quiescence of multipotent progenitors (MPPs). This property of quizartinib conferred marked protection to MPPs in mice receiving fluorouracil or gemcitabine. The protection resulted in the rapid recovery of bone marrow and blood cellularity, thus preventing otherwise lethal myelosuppression. A treatment strategy involving quizartinib priming that protected wild-type bone marrow progenitors, but not leukemic cells, from fluorouracil provided a more effective treatment than conventional induction therapy in mouse models of acute myeloid leukemia. This strategy has the potential to be extended for use in other cancers where FLT3 inhibition does not adversely affect the effectiveness of chemotherapy. Thus, the addition of quizartinib to cancer treatment regimens could markedly improve cancer patient survival and quality of life.

Transient CDK4/6 inhibition protects hematopoietic stem cells from chemotherapy-induced exhaustion

Conventional cytotoxic chemotherapy is highly effective in certain cancers but causes dose-limiting damage to normal proliferating cells, especially hematopoietic stem and progenitor cells (HSPCs). Serial exposure to cytotoxics causes a long-term hematopoietic compromise ("exhaustion"), which limits the use of chemotherapy and success of cancer therapy. We show that the coadministration of G1T28 (trilaciclib), which is a small-molecule inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6), contemporaneously with cytotoxic chemotherapy protects murine hematopoietic stem cells (HSCs) from chemotherapy-induced exhaustion in a serial 5-fluorouracil treatment model. Consistent with a cell-intrinsic effect, we show directly preserved HSC function resulting in a more rapid recovery of peripheral blood counts, enhanced serial transplantation capacity, and reduced myeloid skewing. When administered to healthy human volunteers, G1T28 demonstrated excellent in vivo pharmacology and transiently inhibited bone marrow (BM) HSPC proliferation. These findings suggest that the combination of CDK4/6 inhibitors with cytotoxic chemotherapy should provide a means to attenuate therapy-induced BM exhaustion in patients with cancer.

Public data mining plus domestic experimental study defined involvement of the old-yet-uncharacterized gene matrix-remodeling associated 7 (MXRA7) in physiopathology of the eye

Matrix-remodeling associated 7 (MXRA7) gene was first reported in 2002 and named so for its co-expression with several genes known to relate with matrix-remodeling. However, not any studies had been intentionally performed to characterize this gene. We started defining the functions of MXRA7 by integrating bioinformatics analysis and experimental study. Data mining of MXRA7 expression in BioGPS, Gene Expression Omnibus and EurExpress platforms highlighted high level expression of Mxra7 in murine ocular tissues. Real-time PCR was employed to measure Mxra7 mRNA in tissues of adult C57BL/6 mice and demonstrated that Mxra7 was preferentially expressed at higher level in retina, corneas and lens than in other tissues. Then the inflammatory corneal neovascularization (CorNV) model and fungal corneal infections were induced in Balb/c mice, and mRNA levels of Mxra7 as well as several matrix-remodeling related genes (Mmp3, Mmp13, Ecm1, Timp1) were monitored with RT-PCR. The results demonstrated a time-dependent Mxra7 under-expression pattern (U-shape curve along timeline), while all other matrix-remodeling related genes manifested an opposite changes pattern (dome-shape curve). When limited data from BioGPS concerning human MXRA7 gene expression in human tissues were looked at, it was found that ocular tissue was also the one expressing highest level of MXRA7. To conclude, integrative assay of MXRA7 gene expression in public databank as well as domestic animal models revealed a selective high expression MXRA7 in murine and human ocular tissues, and its change patterns in two corneal disease models implied that MXRA7 might play a role in pathological processes or diseases involving injury, neovascularization and would healing.

Common extracellular matrix regulation of myeloid cell activity in the bone marrow and tumor microenvironments

The complex interaction between cells undergoing transformation and the various stromal and immunological cell components of the tumor microenvironment (TME) crucially influences cancer progression and diversification, as well as endowing clinical and prognostic significance. The immunosuppression characterizing the TME depends on the recruitment and activation of different cell types including regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages. Less considered is the non-cellular component of the TME. Here, we focus on the extracellular matrix (ECM) regulatory activities that, within the TME, actively contribute to many aspects of tumor progression, acting on both tumor and immune cells. Particularly, ECM-mediated regulation of tumor-associated immunosuppression occurs through the modulation of myeloid cell expansion, localization, and functional activities. Such regulation is not limited to the TME but occurs also within the bone marrow, wherein matricellular proteins contribute to the maintenance of specialized hematopoietic stem cell niches thereby regulating their homeostasis as well as the generation and expansion of myeloid cells under both physiological and pathological conditions. Highlighting the commonalities among ECM-myeloid cell interactions in bone marrow and TME, in this review we present a picture in which myeloid cells might sense and respond to ECM modifications, providing different ECM-myeloid cell interfaces that may be useful to define prognostic groups and to tailor therapeutic interventions.

Adiponectin Enhances Quiescence Exit of Murine Hematopoietic Stem Cells and Hematopoietic Recovery Through mTORC1 Potentiation

Myelotoxic injury, such as chemotherapeutic agents and ionizing radiation, unlocks the vigorous power of hematopoietic stem cells (HSCs) to replenish the hematopoietic system, making quiescent HSCs enter the cell cycle. Considering that both HSC-intrinsic and -extrinsic mechanisms enforce quiescence of HSCs, the drastic change in bone marrow (BM) environment after injury, represented by massive expansion of BM adipocytes, might trigger HSC activation. BM adipocytes, the major cellular component in the ablated marrow, however, reportedly suppress proliferation of hematopoietic cells, which may indicate the BM adipocytogenesis is an irrational response of injured organism. Given that adipose tissue is an endocrine organ with pleiotropic functions, we hypothesized that adipocyte-derived factors, especially adiponectin, an anti-inflammatory adipokine involved in regulation of granulopoiesis, are implicated in HSC activation. Myeloablative intervention increased BM adiponectin by multiple mechanisms, including adipocyte expansion and increased diffusion from the blood. Adiponectin-null (Adipoq ^-/- ) mice showed delayed hematopoietic recovery after BM injury, with Adipoq^-/- HSCs more quiescent and defective in mammalian target of rapamycin complex 1 (mTORC1) activation. Recombinant adiponectin promoted not only HSC activation in vivo but cytokine-induced activation in vitro, and shortened the time for exit from quiescence in an mTORC1-dependent manner. These data illustrate a scarcely-reported example of a cell-extrinsic factor, adiponectin, enhancing quiescence exit of HSCs, and subsequent hematopoietic recovery. Our findings also highlight adipocytes as a source of adiponectin to ensure the proliferative burst of hematopoietic cells in ablated marrow. Stem Cells 2017;35:1835-1848.

p190-B RhoGAP and intracellular cytokine signals balance hematopoietic stem and progenitor cell self-renewal and differentiation

The mechanisms regulating hematopoietic stem and progenitor cell (HSPC) fate choices remain ill-defined. Here, we show that a signalling network of p190-B RhoGAP-ROS-TGF-β-p38^MAPK balances HSPC self-renewal and differentiation. Upon transplantation, HSPCs express high amounts of bioactive TGF-β1 protein, which is associated with high levels of p38^MAPK activity and loss of HSC self-renewal in vivo. Elevated levels of bioactive TGF-β1 are associated with asymmetric fate choice in vitro in single HSPCs via p38MAPK activity and this is correlated with the asymmetric distribution of activated p38MAPK. In contrast, loss of p190-B, a RhoGTPase inhibitor, normalizes TGF-β levels and p38MAPK activity in HSPCs and is correlated with increased HSC self-renewal in vivo. Loss of p190-B also promotes symmetric retention of multi-lineage capacity in single HSPC myeloid cell cultures, further suggesting a link between p190-B-RhoGAP and non-canonical TGF-β signalling in HSPC differentiation. Thus, intracellular cytokine signalling may serve as ‘fate determinants' used by HSPCs to modulate their activity.

The success of hematopoietic stem cell (HSC) transplantation relies on understanding what regulates the fate decision to self-renew. Here, the authors show using both in vitro assays and in vivo transplantation that loss of the RhoGAP p190-B enhances self-renewal by inhibiting TGFβ/p38 signalling.

Thioredoxin-interacting protein regulates haematopoietic stem cell ageing and rejuvenation by inhibiting p38 kinase activity

Ageing is a natural process in living organisms throughout their lifetime, and most elderly people suffer from ageing-associated diseases. One suggested way to tackle such diseases is to rejuvenate stem cells, which also undergo ageing. Here we report that the thioredoxin-interacting protein (TXNIP)-p38 mitogen-activated protein kinase (p38) axis regulates the ageing of haematopoietic stem cells (HSCs), by causing a higher frequency of long-term HSCs, lineage skewing, a decrease in engraftment, an increase in reactive oxygen species and loss of Cdc42 polarity. TXNIP inhibits p38 activity via direct interaction in HSCs. Furthermore, cell-penetrating peptide (CPP)-conjugated peptide derived from the TXNIP-p38 interaction motif inhibits p38 activity via this docking interaction. This peptide dramatically rejuvenates aged HSCs in vitro and in vivo. Our findings suggest that the TXNIP-p38 axis acts as a regulatory mechanism in HSC ageing and indicate the potent therapeutic potential of using CPP-conjugated peptide to rejuvenate aged HSCs.

The processes regulating the ageing of stem cells are not clearly defined. Here, the authors report that in haematopoietic stem cells (HSC) thioredoxin-interacting protein, known to regulate the cell cycle, binds to p38 mitogen-activated protein kinase and regulates HSC ageing and rejuvenation.

Smoc2 potentiates proliferation of hepatocellular carcinoma cells via promotion of cell cycle progression

AIM

To determine the influence of Smoc2 on hepatocellular carcinoma (HCC) cell proliferation and to find a possible new therapeutic target for preventing HCC progression.

METHODS

We detected expression of Smoc2 in HCC tissues and corresponding non-tumor liver (CNL) tissues using PCR, western blot, and immunohistochemistry methods. Subsequently, we down-regulated and up-regulated Smoc2 expression using siRNA and lentivirus transfection assay, respectively. Then, we identified the effect of Smoc2 on cell proliferation and cell cycle using CCK-8 and flow cytometry, respectively. The common cell growth signaling influenced by Smoc2 was detected by western blot assay.

RESULTS

The expression of Smoc2 was significantly higher in HCC tissues compared with CNL tissues. Overexpression of Smoc2 promoted HCC cell proliferation and cell cycle progression. Down-regulation of Smoc2 led to inhibition of cell proliferation and cell cycle progression. Smoc2 had positive effect on ERK and AKT signaling.

CONCLUSION

Smoc2 promotes the proliferation of HCC cells through accelerating cell cycle progression and might act as an anti-cancer therapeutic target in the future.

Akt and β-catenin contribute to TMZ resistance and EMT of MGMT negative malignant glioma cell line

Glioblastoma is one of the most lethal cancers in central nervous system, and some individual cells that cannot be isolated for surgical resection and also show treatment-resistance induce poor prognosis. Hence, in order to research these cells, we treated temozolomide (TMZ)-sensitive U87MG cells with 400μM TMZ in culture media for over 6months and established TMZ-resistant cell line designated as U87/TR. We detected the MGMT status through pyrosequencing and western blotting, and we also assessed the proliferation, migration, EMT-like changes and possible activated signaling pathways in U87/TR cells. Our results demonstrated that U87/TR was MGMT negative, which indicated that MGMT made no contribution for TMZ-resistance of U87/TR. And U87/TR cells displayed cell cycle arrest, higher capacity for migration and EMT-like changes including both phenotype and characteristic proteins. We also revealed that both β-catenin and the phosphorylation level of Akt and PRAS40 were increased in U87/TR, while we did not observe the phosphorylation of mTOR in U87/TR. It indicated that activation of Akt and Wnt/β-catenin pathways may be response for the chemo-resistance and increased invasion of U87/TR cells, and the phosphorylation of PRAS40 and inactivated mTOR may be related to cell cycle arrest in U87/TR cells.

OP9 Stromal Cells Proteins Involved in Hematoendothelial Differentiation from Human Embryonic Stem Cells

Hematopoietic cells (HCs) and endothelial cells (ECs) can be produced in vitro from human embryonic stem cells (hESCs), but the differentiation systems used are still inefficient. To overcome this obstacle, it is necessary to understand the differentiation process. One of the methods used to obtain HCs and ECs from hESCs is their co-culture with stromal cells. The soluble factors secreted by these cells and cell-cell contact have a great impact on the differentiation process. Here, we performed comparative proteomic analyses of proteins obtained from the total extract of OP9 stromal cells and secreted by these cells before and during in vitro generation of HCs and ECs (hematoendothelial) from hESCs. We identified a total of 83 secreted and 759 intracellular proteins during differentiation. Twenty-five secreted and 181 proteins from the total extract were more abundant. Some secreted proteins are involved in cell-matrix interactions and HC and/or EC development. Moreover, 13 proteins of the total extract from OP9 cells that were exclusive/or more abundant during differentiation are involved in the Nrf2/Nfe2l2 gene pathway, that is, they are described to have a key role in oxidative stress and in hematopoietic development and maturation. Our proteomic profiles provide valuable insight about the proteins involved in in vitro hematoendothelial cell generation and in the future they might be used to optimize the differentiation process and produce both cell types in vitro.

An Attempt to Evaluate Selected Aspects of "Bone-Fat Axis" Function in Healthy Individuals and Patients With Pancreatic Cancer

Recently, much attention has been paid to a potential biochemical cross-talk between the metabolism of the adipose tissue (AT) and bone (marrow), termed "bone-fat axis." We hypothesized that selected substances, participating in this "dialog," are associated with body mass and peripheral trafficking of bone marrow-derived stem cells (BMSCs) in both healthy individuals and patients with obesity-associated malignancies such as pancreatic adenocarcinoma.We performed an analysis of the systemic levels of selected substances involved in the regulation of bone (marrow) homeostasis (parathormone, calcitonin, osteopontin, osteonectin, stem cell factor [SCF], and fibroblast growth factor-23) in 35 generally healthy volunteers and 35 patients with pancreatic cancer. Results were correlated with the absolute number of circulating BMSCs and body mass values. Additionally, subcutaneous and visceral/omental AT levels of the aforementioned molecules were analyzed in lean and overweight/obese individuals.Intensified steady-state trafficking of only Lin-CD45 + CD133 + hematopoietic stem/progenitor cells was observed in overweight/obese individuals and this was associated with BMI values and elevated levels of both osteonectin and SCF, which also correlated with BMI. In comparison to healthy individuals, patients with cancer had significantly higher osteopontin levels and lower values of both osteonectin and osteonectin/osteopontin ratio. While no significant correlation was observed between BMI and the number of circulating BMSCs in patients with cancer, peripheral trafficking of CD34 + KDR + CD31 + CD45-endothelial progenitor cells and CD105 + STRO-1 + CD45-mesenchymal stem cells was associated with the osteonectin/osteopontin ratio, which also correlated with BMI (r = 0.52; P < 0.05). AT levels of the examined substances were similar to those measured in the plasma, except for osteonectin, which was about 10 times lower.Our study highlights the potential role of osteonectin, osteopontin, and SCF as communication signals between the bone (marrow) and AT in both healthy individuals and patients with pancreatic cancer. We postulate that these molecules may be overlooked biochemical players linking body mass and BMSCs with obesity-associated cancer development and/or progression in humans.

Microenvironment, tumor cell plasticity, and cancer

PURPOSE OF REVIEW

Much effort has been devoted to determining how cellular and noncellular components of the tumoral niche initiate and promote cancer development. Cancer cells perceive biochemical signals from components of the extracellular matrix (ECM) and sense physical features, such as matrix stiffness and cell confinement. The past decade has seen a better understanding of the biophysics and mechanobiology associated with cancer cells. Indeed, loss of mechanisms controlling the production, the degradation, and the remodeling of ECM contributes to tumor growth or cell dissemination by affecting cell contractility in response to ECM stiffness and by stimulating mechanical dependence of growth factor activation.

RESULTS

Cell plasticity allows adaptative strategies for cancer cells to survive or eventually escape from tumoral environment through modification of the microenvironment-cell interface, internal tension increase, and nuclear deformation partly leading to intratumoral heterogeneity. However, although alteration of the biomechanical properties of the ECM are sufficient to promote cell migration and invasion in cancer cells, this microenvironment can also provide a hospitable niche for tumor dormancy and resistance to cancer therapy.

CONCLUSION

The review will focus on how physicochemical properties of ECM might promote tumor growth or cell dissemination or on the contrary maintain quiescent state of cancer cells. It is crucial to clarify the molecular basis of mechanotransduction in the development and progression of tumors to identify new potential biomarkers and anticancer therapeutic targets.

Systems biology approach to developing S2RM-based “systems therapeutics” and naturally induced pluripotent stem cells

The degree to, and the mechanisms through, which stem cells are able to build, maintain, and heal the body have only recently begun to be understood. Much of the stem cell’s power resides in the release of a multitude of molecules, called stem cell released molecules (SRM). A fundamentally new type of therapeutic, namely “systems therapeutic”, can be realized by reverse engineering the mechanisms of the SRM processes. Recent data demonstrates that the composition of the SRM is different for each type of stem cell, as well as for different states of each cell type. Although systems biology has been successfully used to analyze multiple pathways, the approach is often used to develop a small molecule interacting at only one pathway in the system. A new model is emerging in biology where systems biology is used to develop a new technology acting at multiple pathways called “systems therapeutics”. A natural set of healing pathways in the human that uses SRM is instructive and of practical use in developing systems therapeutics. Endogenous SRM processes in the human body use a combination of SRM from two or more stem cell types, designated as S²RM, doing so under various state dependent conditions for each cell type. Here we describe our approach in using state-dependent SRM from two or more stem cell types, S²RM technology, to develop a new class of therapeutics called “systems therapeutics.” Given the ubiquitous and powerful nature of innate S²RM-based healing in the human body, this “systems therapeutic” approach using S²RM technology will be important for the development of anti-cancer therapeutics, antimicrobials, wound care products and procedures, and a number of other therapeutics for many indications.

Cutting the brakes on hematopoietic regeneration by blocking TGFβ to limit chemotherapy-induced myelosuppression

Hematopoietic stressors such as infection, bleeding, or toxic injury trigger a hematopoietic adaptation that sacrifices hematopoietic stem and progenitor cell (HSPC) quiescence to meet an urgent need for new blood cell production. Once the hematopoietic demands are adequately met, homeostasis must be restored. Transforming growth factor β (TGFβ) signaling is a central mediator mandating the return of HSPCs to quiescence after stress. Blockade of TGFβ signaling after hematopoietic stress delays the return of cycling HSPCs to quiescence and in so doing promotes hematopoietic stem cell (HSC) self-renewal and accelerates hematopoietic reconstitution. These findings open the door to new therapeutics that modulate the hematopoietic adaptation to stress. In this review, we will discuss the complex context-dependent activities of TGFβ in hematopoiesis and the potential benefits and limitations of using TGFβ pathway inhibitors to promote multilineage hematopoietic reconstitution after myelosuppressive chemotherapy.