Epidermal Growth Factor Receptor Family Inhibition Identifies P38 Mitogen-activated Protein Kinase as a Potential Therapeutic Target in Bladder Cancer

p38 Mediates Resistance to FGFR Inhibition in Non-Small Cell Lung Cancer

FGFR signalling is one of the most prominent pathways involved in cell growth and development as well as cancer progression. FGFR1 amplification occurs in approximately 20% of all squamous cell lung carcinomas (SCC), a predominant subtype of non-small cell lung carcinoma (NSCLC), indicating FGFR as a potential target for the new anti-cancer treatment. However, acquired resistance to this type of therapies remains a serious clinical challenge. Here, we investigated the NSCLC cell lines response and potential mechanism of acquired resistance to novel selective FGFR inhibitor CPL304110. We found that despite significant genomic differences between CPL304110-sensitive cell lines, their resistant variants were characterised by upregulated p38 expression/phosphorylation, as well as enhanced expression of genes involved in MAPK signalling. We revealed that p38 inhibition restored sensitivity to CPL304110 in these cells. Moreover, the overexpression of this kinase in parental cells led to impaired response to FGFR inhibition, thus confirming that p38 MAPK is a driver of resistance to a novel FGFR inhibitor. Taken together, our results provide an insight into the potential direction for NSCLC targeted therapy.

Sulforaphane Impact on Reactive Oxygen Species (ROS) in Bladder Carcinoma

Sulforaphane (SFN) is a natural glucosinolate found in cruciferous vegetables that acts as a chemopreventive agent, but its mechanism of action is not clear. Due to antioxidative mechanisms being thought central in preventing cancer progression, SFN could play a role in oxidative processes. Since redox imbalance with increased levels of reactive oxygen species (ROS) is involved in the initiation and progression of bladder cancer, this mechanism might be involved when chemoresistance occurs. This review summarizes current understanding regarding the influence of SFN on ROS and ROS-related pathways and appraises a possible role of SFN in bladder cancer treatment.

Limited inhibition of multiple nodes in a driver network blocks metastasis

Metastasis suppression by high-dose, multi-drug targeting is unsuccessful due to network heterogeneity and compensatory network activation. Here, we show that targeting driver network signaling capacity by limited inhibition of core pathways is a more effective anti-metastatic strategy. This principle underlies the action of a physiological metastasis suppressor, Raf Kinase Inhibitory Protein (RKIP), that moderately decreases stress-regulated MAP kinase network activity, reducing output to transcription factors such as pro-metastastic BACH1 and motility-related target genes. We developed a low-dose four-drug mimic that blocks metastatic colonization in mouse breast cancer models and increases survival. Experiments and network flow modeling show limited inhibition of multiple pathways is required to overcome variation in MAPK network topology and suppress signaling output across heterogeneous tumor cells. Restricting inhibition of individual kinases dissipates surplus signal, preventing threshold activation of compensatory kinase networks. This low-dose multi-drug approach to decrease signaling capacity of driver networks represents a transformative, clinically relevant strategy for anti-metastatic treatment.

ErbB4 regulate extracellular dopamine through the p38 MAPK signaling pathway

ErbB4 loss-of-function in catecholaminergic neurons induces catecholamine dyshomeostasis. Despite ErbB4's significant role in neuropathology, the signaling pathways that regulate these changes are still widely unknown. In this study, we attempt to identify the downstream pathway of ErbB4 that regulates catecholamine homeostasis. The SH-SY5Y human neuroblastoma cell line was used as the in vitro model for catecholaminergic neurons. Western blotting, enzyme-linked immunosorbent assay, and pharmacological and genetic manipulations by agonist/antagonist or small interference RNA were used to investigate the relationship between ErbB4 and extracellular catecholamines. We confirmed that ErbB4 is abundantly expressed in undifferentiated and retinoic acid-differentiated catecholaminergic cells from the SH-SY5Y cell line. ErbB4 inhibition increase the ratio of phosphorylated p38 to total p38 in SH-SY5Y human neuroblastoma cells. Consistent with previous in vivo observations in mice, ErbB4 deficiency led to increases in extracellular dopamine and norepinephrine levels. However, the resulting increase in extracellular dopamine, but not norepinephrine, could be suppressed by p38 inhibitor SB202190. Our results suggest that both extracellular dopamine and norepinephrine homeostasis could be regulated by ErbB4 in human catecholaminergic cells, and ErbB4 may regulate extracellular dopamine, but not norepinephrine, through the p38 MAPK signaling pathway, thus indicating different regulatory pathways of dopamine and norepinephrine by ErbB4 in catecholaminergic neurons.

1,4-Benzodioxane, an evergreen, versatile scaffold in medicinal chemistry: A review of its recent applications in drug design

1,4-Benzodioxane has long been a versatile template widely employed to design molecules endowed with diverse bioactivities. Its use spans the last decades of medicinal chemistry until today concerning many strategies of drug discovery, not excluding the most advanced ones. Here, more than fifty benzodioxane-related lead compounds, selected from recent literature, are presented showing the different approaches with which they have been developed. Agonists and antagonists at neuronal nicotinic, α₁ adrenergic and serotoninergic receptor subtypes and antitumor and antibacterial agents form the most representative classes, but a variety of other biological targets are addressed by benzodioxane-containing compounds.

Lapatinib sensitivity in nasopharyngeal carcinoma is modulated by SIRT2-mediated FOXO3 deacetylation

Background

Chemoresistance is an obstacle to the successful treatment of nasopharyngeal carcinoma (NPC). Lapatinib is a targeted tyrosine kinase inhibitor therapeutic drug also used to treat NPC, but high doses are often required to achieve a result. To investigate the mechanism for the development of Lapatinib resistance, we characterised a number of NPC cell lines to determine the role of FOXO3 and sirtuins in regulating NPC resistance.

Methods

Sulforhodamine B (SRB) assays, Clonogenic assays, Protein extraction, quantification and western blotting, RT qPCR, Co-immunoprecipitation assay.

Results

To explore novel treatment strategies, we first characterized the Lapatinib-sensitivity of a panel of NPC cell lines by SRB and clonogenic cytotoxic assays and found that the metastatic NPC (C666–1 and 5-8F) cells are highly resistant whereas the poorly metastatic lines (6-10B, TW01 and HK-1) are sensitive to Lapatinib. Western blot analysis of the Lapatinib-sensitive 6-10B and resistant 5-8F NPC cells showed that the expression of phosphorylated/inactive FOXO3 (P-FOXO3;T32), its target FOXM1 and its regulator SIRT2 correlate negatively with Lapatinib response and sensitivity, suggesting that SIRT2 mediates FOXO3 deacetylation to promote Lapatinib resistance. In agreement, clonogenic cytotoxic assays using wild-type and foxo1/3/4^−/− mouse embryonic fibroblasts (MEFs) showed that FOXO1/3/4-deletion significantly attenuates Lapatinib-induced cytotoxicity, confirming that FOXO proteins are essential for mediating Lapatinib response. SRB cell viability assays using chemical SIRT inhibitors (i.e. sirtinol, Ex527, AGK2 and AK1) revealed that all SIRT inhibitors can reduce NPC cell viability, but only the SIRT2-specific inhibitors AK1 and AGK2 further enhance the Lapatinib cytotoxicity. Consistently, clonogenic assays demonstrated that the SIRT2 inhibitors AK1 and AGK2 as well as SIRT2-knockdown increase Lapatinib cytotoxicity further in both the sensitive and resistant NPC cells. Co-immunoprecipitation studies showed that besides Lapatinib treatment, SIRT2-pharmaceutical inhibition and silencing also led to an increase in FOXO3 acetylation. Importantly, SIRT2 inhibition and depletion further enhanced Lapatinib-mediated FOXO3-acetylation in NPC cells.

Conclusion

Collectively, our results suggest the involvement of SIRT2-mediated FOXO3 deacetylation in Lapatinib response and sensitivity, and that SIRT2 can specifically antagonise the cytotoxicity of Lapatinib through mediating FOXO3 deacetylation in both sensitive and resistant NPC cells. The present findings also propose that SIRT2 can be an important biomarker for metastatic and Lapatinib resistant NPC and that targeting the SIRT2-FOXO3 axis may provide novel strategies for treating NPC and for overcoming chemoresistance.

Discovery of potent p38α MAPK inhibitors through a funnel like workflow combining in silico screening and in vitro validation

This work describes the rational discovery of novel chemotypes of p38α MAPK inhibitors using a funnel approach consisting of several computer-aided drug discovery methods and biological experiments. Among the identified hits, four compounds belonging to different chemical families showed IC₅₀ values lower than 10 μM. In particular, the 1,4-benzodioxane derivative 5 turned out to be a potent and efficient p38α MAPK inhibitor having IC₅₀ = 0.07 μM, and LE_exp and LipE values of 0.38 and 4.8, respectively; noteworthy, the compound had also a promising kinase selectivity profile and the capability to suppress p38α MAPK effects in human immune cells. Overall, the collected findings highlight that the applied strategy has been successful in generating chemical novelty in the inhibitor kinase field, providing suitable chemical candidates for further inhibitor optimization.

Semaphorin 4D promotes the proliferation and metastasis of bladder cancer by activating the PI3K/AKT pathway

The present study aimed to investigate the role of semaphorin 4D (Sema4D) in bladder cancer cell proliferation and metastasis in vivo and in vitro. Effects of Sema4D modulation on cancer cell viability and clonogenic abilities were assessed by MTT assay and colony formation assay. Cell apoptosis, cell cycle analysis, transwell assays, and wound-healing assays were also assayed. A mouse model of bladder cancer was established to observe the tumorigenesis in vivo. Our data showed that Sema4D was 4-fold upregulated in clinical bladder cancer tissues relative to noncancerous ones and differentially expressed in bladder cancer cell lines. Knockdown of Sema4D in bladder cancer T24 and 5637 cells significantly decreased cell proliferation, clonogenic potential, and motility. On the contrary, overexpression of Sema4D in bladder cancer SV-HUC-1 cells significantly increased cell viability and motility. Concordantly, knockdown of Sema4D impaired while overexpression of Sema4D promoted bladder cancer cell growth rates in xenotransplanted mice. Cell cycle was arrested by modulation of Sema4D. Cell apoptotic rates and the mitochondrial membrane potentials were consistently increased upon knockdown of Sema4D in T24 cells and 5637 cells. Western blotting revealed that epithelial-mesenchymal transition was promoted by Sema4D. The PI3K/AKT pathway was activated upon Sema4D overexpression in SV-HUC-1 cells, while it was inactivated by knockdown of Sema4D in T24 cells. All these data suggest that Sema4D promotes cell proliferation and metastasis in bladder cancer in vivo and in vitro. The oncogenic behavior of Sema4D is achieved by activating the PI3K/AKT pathway.

Src inhibition induces melanogenesis in human G361 cells

The Src kinase family (SKF) includes non-receptor tyrosine kinases that interact with many cellular cytosolic, nuclear and membrane proteins, and is involved in the progression of cellular transformation and oncogenic activity. However, there is little to no evidence on the effect of SKF or its inhibitors on melanogenesis. Therefore, the present study investigated whether C-terminal Src kinase inhibition can induce melanogenesis and examined the associated signaling pathways and mRNA expression of melanogenic proteins. First, whether stimulators of melanogenesis, such as ultraviolet B and α-melanocyte-stimulating hormone, can dephosphorylate Src protein was evaluated, and the results revealed that SU6656 and PP2 inhibited the phosphorylation of Src in G361 cells. Src inhibition by these chemical inhibitors induced melanogenesis in G361 cells and upregulated the mRNA expression levels of melanogenesis-associated genes encoding microphthalmia-associated transcription factor, tyrosinase-related protein 1 (TRP1), TRP2, and tyrosinase. In addition, Src inhibition by small interfering RNA induced melanogenesis and upregulated the mRNA expression levels of melanogenesis-associated genes. As the p38 mitogen-activated protein kinase (MAPK) and cyclic adenosine monophosphate response element binding (CREB) pathways serve key roles in melanogenesis, the present study further examined whether Src mediates melanogenesis via these pathways. As expected, Src inhibition via SU6656 or PP2 administration induced the phosphorylation of p38 or CREB, as determined by western blotting analysis, and increased the levels of phosphorylated p38 or CREB, as determined by immunofluorescence staining. In addition, the induced pigmentation and melanin content of G361 cells by Src inhibitors was significantly inhibited by p38 or CREB inhibitors. Taken together, these data indicate that Src is associated with melanogenesis, and Src inhibition induces melanogenesis via the MAPK and CREB pathways in G361 cells.

HER2 and Src co-regulate proliferation, migration and transformation by downstream signaling pathways in arsenite-treated human uroepithelial cells

HER2 mediate proliferation, migration and transformation by multiple downstream signaling pathways in arsenite-treated human uroepithelial cells.