A trigger model of apoptosis induced by tumor necrosis factor signaling

TNFα induces Caspase-3 activity in hematopoietic progenitor cells CD34+, CD33+, and CD41 + of myelodysplastic syndromes

BACKGROUND

Cytopenia is the primary feature of Myelodysplastic Syndrome, even in the presence of hypercellular bone marrow. TNFα is recognized as both a proinflammatory, and proapoptotic cytokine with a well established role in promoting apoptosis in MDS. Therefore, TNFα has the potential to be a valuable biomarker for predicting the progression of cytopenia in MDS. This study aims to establish the role of TNFα exposure in triggering apoptosis through caspase-3 activity in CD34+, CD33+, and CD41 + cells in MDS.

METHODS

This study is an in vitro comparative experimental research. Bone marrow mononuclear cells were isolated as the source of hematopoietic progenitor cells. Subsequently, CD34+, CD33+, and CD41 + cells were exposed to rhTNFα, and the caspase-3 activity was measured using flowcytometry.

RESULTS

In MDS CD33 + and CD41 + caspase-3 activity of rhTNFα exposed cells was significantly higher than without exposed cells. The opposite result was found in CD34 + cells, where the caspase-3 activity without rhTNFα exposed cells was significantly higher than rhTNFα exposed cells.

CONCLUSION

rhTNFα exposure led to an elevation in caspase-3 activity in MDS progenitor cells, especially in those that had differentiated into myeloid cell CD33 + and megakaryocyte cell CD41+, as opposed to the early progenitor cells CD34+.

Celecoxib, a Non-Steroidal Anti-Inflammatory Drug, Exerts a Toxic Effect on Human Melanoma Cells Grown as 2D and 3D Cell Cultures

Cutaneous melanoma (CM) remains one of the leading causes of tumor mortality due to its high metastatic spread. CM growth is influenced by inflammation regulated by prostaglandins (PGs) whose synthesis is catalyzed by cyclooxygenases (COXs). COX inhibitors, including non-steroidal anti-inflammatory drugs (NSAIDs), can inhibit tumor development and growth. In particular, in vitro experiments have shown that celecoxib, a NSAID, inhibits the growth of some tumor cell lines. However, two-dimensional (2D) cell cultures, used in traditional in vitro anticancer assays, often show poor efficacy due to a lack of an in vivo like cellular environment. Three-dimensional (3D) cell cultures, such as spheroids, are better models because they can mimic the common features displayed by human solid tumors. Hence, in this study, we evaluated the anti-neoplastic potential of celecoxib, in both 2D and 3D cell cultures of A2058 and SAN melanoma cell lines. In particular, celecoxib reduced the cell viability and migratory capability and triggered the apoptosis of melanoma cells grown as 2D cultures. When celecoxib was tested on 3D melanoma cell cultures, the drug exerted an inhibitory effect on cell outgrowth from spheroids and reduced the invasiveness of melanoma cell spheroids into the hydrogel matrix. This work suggests that celecoxib could represent a new potential therapeutic approach in melanoma therapy.

Data-driven multi-scale mathematical modeling of SARS-CoV-2 infection reveals heterogeneity among COVID-19 patients

Patients with coronavirus disease 2019 (COVID-19) often exhibit diverse disease progressions associated with various infectious ability, symptoms, and clinical treatments. To systematically and thoroughly understand the heterogeneous progression of COVID-19, we developed a multi-scale computational model to quantitatively understand the heterogeneous progression of COVID-19 patients infected with severe acute respiratory syndrome (SARS)-like coronavirus (SARS-CoV-2). The model consists of intracellular viral dynamics, multicellular infection process, and immune responses, and was formulated using a combination of differential equations and stochastic modeling. By integrating multi-source clinical data with model analysis, we quantified individual heterogeneity using two indexes, i.e., the ratio of infected cells and incubation period. Specifically, our simulations revealed that increasing the host antiviral state or virus induced type I interferon (IFN) production rate can prolong the incubation period and postpone the transition from asymptomatic to symptomatic outcomes. We further identified the threshold dynamics of T cell exhaustion in the transition between mild-moderate and severe symptoms, and that patients with severe symptoms exhibited a lack of naïve T cells at a late stage. In addition, we quantified the efficacy of treating COVID-19 patients and investigated the effects of various therapeutic strategies. Simulations results suggested that single antiviral therapy is sufficient for moderate patients, while combination therapies and prevention of T cell exhaustion are needed for severe patients. These results highlight the critical roles of IFN and T cell responses in regulating the stage transition during COVID-19 progression. Our study reveals a quantitative relationship underpinning the heterogeneity of transition stage during COVID-19 progression and can provide a potential guidance for personalized therapy in COVID-19 patients.

Coronavirus disease 2019 (COVID-19) is currently destroying both lives and economies. However, patients infected with severe acute respiratory syndrome (SARS)-like coronavirus (SARS-CoV-2) usually present heterogeneous and complicated progressions, such as different incubation periods (short and long), symptoms (asymptomatic and symptomatic) and severity (mild-moderate and severe). Currently, various clinical data and experimental data are available from different countries, which has great significance for integrating different types of data to comprehensively understand the diverse disease progression in COVID-19 patients and guide individual treatment strategies. Here, we developed a multi-scale computational model to describe the dynamical process of patients infected with SARS-CoV-2, including intracellular viral dynamics, multicellular infection process, and immune responses. By combining data integration, stochastic simulation and quantitative analysis based on the multi-scale mathematical model, we addressed an important question regarding how IFN response and T cell exhaustion quantitatively affect heterogeneous progression in patients with respect to incubation periods, symptoms and severity. Furthermore, the efficacy of various therapeutic strategies for treating COVID-19 patients with different severity degrees was evaluated and validated. The computational framework in this study can also be extended to explore the dynamical process of other coronavirus infections.

Protective effects of zingerone derivate on ionizing radiation-induced intestinal injury

Intestinal injury is the primary toxicity of radiotherapy for pelvic and abdominal tumors, and it is also one of the common acute complications of radiotherapy. At present, there are no effective drugs to prevent intestinal injury in the clinic. Zingerone is a natural product with radioprotective effects. In this study, a novel compound (thiazolidine hydrochloride, TZC01) was synthesized by structural modification of zingerone. The effects of TZC01 on preventing intestinal injury from radiation were further investigated in this study. C57BL/6N mice were exposed to a lethal dose of abdominal irradiation (ABI) with and without TZC01 treatments. The morphological changes of the intestine and various makers of intestinal crypt cells were investigated. Treatment with TZC01 improved the survival rate of mice exposed to 12 Gy ABI. Moreover, TZC01 protected the intestinal morphology of mice, decreased the apoptotic rate of intestinal crypt cells, maintained cell regeneration and promoted crypt cell proliferation and differentiation. This study suggests that TZC01 has preventive and therapeutic effects on radiation enteritis by promoting the proliferation and differentiation of crypt cells to protect the small intestine from the toxic effects of ionizing radiation. Furthermore, the study of TCZ01 lays a strong foundation for developing novel radioprotectors with multiple properties.

Intrinsic and induced drug resistance mechanisms: in silico investigations at the cellular and tissue scales

Basic in silico models used to study intrinsic and acquired variants of two types of cellular resistance mechanisms demonstrate important tissue-level differences and consequences.

Towards an integrated systems-based modelling framework for drug transport and its effect on tumour cells

Background

A systematic understanding of chemotherapeutic influence on solid tumours is highly challenging and complex as it encompasses the interplay of phenomena occurring at multiple scales. It is desirable to have a multiscale systems framework capable of disentangling the individual roles of multiple contributing factors, such as transport and extracellular factors, and purely intracellular factors, as well as the interactions among these factors. Based on a recently developed systems-based modelling framework, we have developed a coupled system in order to further elucidate the role of drug transport, and its interplay with cellular signalling by incorporating intra- and extra-vascular drug transport in tumour, dynamic descriptions of intracellular signalling and tumour cell density dynamics.

Results

Different aspects of the interaction between transport and cell signalling and the effects of transport parameters have been investigated in silico. Limited drug penetration is found to be a major constraint in inducing drug effect; many aspects of the interaction of transport with cell signalling are independent of the details of cell signalling. A sensitivity analysis indicates that the effect of drug diffusivity depends on the balance between interstitial drug transport and the specific requirement for triggering apoptosis (governed by highly nonlinear signalling networks), suggesting that the effect of drug diffusivity in such cases must be considered in conjunction with descriptions of cellular dynamics.

Conclusions

The modelling framework developed in this study provides qualitative and mechanistic insights into the effect of drug on tumour cells. It provides an in silico experimental platform to investigate the interplay between extracellular factors (e.g. transport) and intracellular factors. Such a platform is essential to understanding the individual and combined effects of transport and cellular factors in solid tumour.

Investigating the effects of ABC transporter-based acquired drug resistance mechanisms at the cellular and tissue scale

In this paper we systematically investigate the effects of acquired drug resistance at the cellular and tissue scale, with a specific focus on ATP-binding cassette (ABC) transporter-based mechanisms and contrast this with other representative intracellular resistance mechanisms. This is done by developing in silico models wherein the drug resistance mechanism is overlaid on a coarse-grained description of apoptosis; these cellular models are coupled with interstitial drug transport, allowing for a transparent examination of the effect of acquired drug resistances at the tissue level. While ABC transporter-mediated resistance mechanisms counteract drug effect at the cellular level, its tissue-level effect is more complicated, revealing unexpected trends in tissue response as drug stimuli are systematically varied. Qualitatively different behaviour is observed in other drug resistance mechanisms. Overall the paper (i) provides insight into the tissue level functioning of a particular resistance mechanism, (ii) shows that this is very different from other resistance mechanisms of an apparently similar type, and (iii) demonstrates a concrete instance of how the functioning of a negative feedback based cellular adaptive mechanism can have unexpected higher scale effects.

Death ligand concentration and the membrane proximal signaling module regulate the type 1/type 2 choice in apoptotic death signaling

Apoptotic death pathways are frequently activated by death ligand induction and subsequent activation of the membrane proximal signaling module. Death receptors cluster upon binding to death ligands, leading to formation of a membrane proximal death-inducing-signaling-complex (DISC). In this membrane proximal signalosome, initiator caspases (caspase 8) are processed resulting in activation of both type 1 and type 2 pathways of apoptosis signaling. How the type 1/type 2 choice is made is an important question in the systems biology of apoptosis signaling. In this study, we utilize a Monte Carlo based in silico approach to elucidate the role of membrane proximal signaling module in the type 1/type 2 choice of apoptosis signaling. Our results provide crucial mechanistic insights into the formation of DISC signalosome and caspase 8 activation. Increased concentration of death ligands was shown to correlate with increased type 1 activation. We also study the caspase 6 mediated system level feedback activation of apoptosis signaling and its role in the type 1/type 2 choice. Our results clarify the basis of cell-to-cell stochastic variability in apoptosis activation and ramifications of this issue is further discussed in the context of therapies for cancer and neurodegenerative disorders.

Monte carlo study elucidates the type 1/type 2 choice in apoptotic death signaling in healthy and cancer cells

Apoptotic cell death is coordinated through two distinct (type 1 and type 2) intracellular signaling pathways. How the type 1/type 2 choice is made remains a central problem in the biology of apoptosis and has implications for apoptosis related diseases and therapy. We study the problem of type 1/type 2 choice in silico utilizing a kinetic Monte Carlo model of cell death signaling. Our results show that the type 1/type 2 choice is linked to deterministic versus stochastic cell death activation, elucidating a unique regulatory control of the apoptotic pathways. Consistent with previous findings, our results indicate that caspase 8 activation level is a key regulator of the choice between deterministic type 1 and stochastic type 2 pathways, irrespective of cell types. Expression levels of signaling molecules downstream also regulate the type 1/type 2 choice. A simplified model of DISC clustering elucidates the mechanism of increased active caspase 8 generation and type 1 activation in cancer cells having increased sensitivity to death receptor activation. We demonstrate that rapid deterministic activation of the type 1 pathway can selectively target such cancer cells, especially if XIAP is also inhibited; while inherent cell-to-cell variability would allow normal cells stay protected.

Markers of mitochondrial dysfunction during the diclofenac-induced apoptosis in melanoma cell lines

Melanoma is an aggressive cutaneous cancer, whose incidence is growing in recent years, especially in the younger population. The favorable therapy for this neoplasm consists in its early surgical excision; otherwise, in case of late diagnosis, melanoma becomes very refractory to any conventional therapy. Nevertheless, the acute inflammatory response occurring after excision of the primary melanoma can affect the activation and/or regulation of melanoma invasion and metastasis. Nonsteroidal anti-inflammatory drugs (NSAIDs), widely employed in clinical therapy as cyclooxygenase inhibitors, also display a cytotoxic effect on some cancer cell lines; therefore, their possible usage in combination with conventional chemo- and radio-therapies of tumors is being considered. In particular, diclofenac, one of the most common NSAIDs, displays its anti-proliferative effect in many tumor lines, through an alteration of the cellular redox state. In this study, the possible anti-neoplastic potential of diclofenac on the human melanoma cell lines A2058 and SAN was investigated, and a comparison was made with the results obtained from the nonmalignant fibroblast cell line BJ-5ta. Either in A2058 or SAN, the diclofenac treatment caused typical apoptotic morphological changes, as well as an increase of the number of sub-diploid nuclei; conversely, the same treatment on BJ-5ta had only a marginal effect. The observed decrease of Bcl-2/Bax ratio and a parallel increase of caspase-3 activity confirmed the pro-apoptotic role exerted by diclofenac in melanoma cells; furthermore, the drug provoked an increase of the ROS levels, a decrease of mitochondrial superoxide dismutase (SOD2), the cytosolic translocation of both SOD2 and cytochrome c, and an increase of caspase-9 activity. Finally, the cytotoxic effect of diclofenac was amplified, in melanoma cells, by the silencing of SOD2. These data improve the knowledge on the effects of diclofenac and suggest that new anti-neoplastic treatments should be based on the central role of mitochondrion in cancer development; under this concern, the possible involvement of SOD2 as a novel target could be considered.

Cell and molecular biology underpinning the effects of PEDF on cancers in general and osteosarcoma in particular

Cancer is becoming an increasingly common disease in which abnormal cells aggressively grow, invade, and metastasize. In this paper, we review the biological functions of PEDF (pigmented epithelium-derived factor) against cancer, with a focus on a particular type of bone cancer called osteosarcoma. PEDF is a 50 kDa glycoprotein and is a potent inhibitor of angiogenesis, via its ability to decrease proliferation and migration of endothelial cells. This paper critically examines the anticancer activities of PEDF via its role in antiangiogenesis, apoptosis-mediated tumor suppression, and increased tumor cell differentiation. Recently, an orthotopic model of osteosarcoma was used to show that treatment with PEDF had the greatest impact on metastases, warranting an evaluation of PEDF efficacy in other types of cancers.

PDCD5-regulated cell fate decision after ultraviolet-irradiation-induced DNA damage

Programmed cell death 5 (PDCD5) is a human apoptosis-related molecule that is involved in both the cytoplasmic caspase-3 activity pathway (by regulating Bax translocation from cytoplasm to mitochondria) and the nuclear pathway (by interacting with Tip60). In this study, we developed a mathematical model of the PDCD5-regulated switching of the cell response from DNA repair to apoptosis after ultraviolet irradiation-induced DNA damage. We established the model by combining several hypotheses with experimental observations. Our simulations indicate that the ultimate cell response to DNA damage is dependent on a signal threshold mechanism, and the PDCD5 promotion of Bax translocation plays an essential role in PDCD5-regulated cell apoptosis. Furthermore, the model simulations revealed that PDCD5 nuclear translocation can attenuate cell apoptosis, and PDCD5 interactions with Tip60 can accelerate DNA damage-induced apoptosis, but the final cell fate decision is insensitive to the PDCD5-Tip60 interaction. These results are consistent with experimental observations. The effect of recombinant human PDCD5 was also investigated and shown to sensitize cells to DNA damage by promoting caspase-3 activity.