Month: June 2020

Organ culture studies as well as mammalian models have also shown that doxorubicin exerts harmful effects on vascular endothelium, leading to impaired vasodilatory response of arteries. It appears that administration of a single dose of doxorubicin in rabbits is associated with rapid deterioration of endothelium-dependent and independent vascular responses. Furthermore, administration of doxorubicin in humans is associated with acute reduction of flow-mediated dilatation in the brachial arteries and of nitric oxide level in the plasma. High-frequency ultrasound with enhanced contrast agents enables in vivo imaging and analysis of blood perfusion. Microbubbles are a contrast agent that enhances the acoustic signal of blood in the circulation; they are small enough to move freely through the bloodstream, and are used as markers for visualization and quantification of regional microvasculature. Fibred confocal fluorescence microscopy was designed for in vivo imaging of fluorescent signals in living animals. The FCFM with its optical mini-probes enables in vivo fluorescent visualization of microvasculature with a minimal invasive intervention. We have set up a platform of live, high-resolution molecular mice imaging, suitable for capturing vessels’ characteristics, arterial blood flow and organs blood volume. This imaging setup enables us to detect acute, real-time, treatment-induced effects within the same individuals and follow them over a period of time. Using both imaging tools, we could observe that doxorubicin had an effect on blood vessels already 3 minutes after administration. The acute reduction in gonadal and femoral blood flow and the impairment of the blood vessels wall may represent an acute universal doxorubicin-related vascular toxicity, an initial event in organ injury. Of all the chemotherapy-induced side effects, the direct vascular injury is the least characterized. The vascular endothelium is an essential barrier that protects the tissues integrity, regulates the homeostasis of water and solvents between the plasma and the tissues and plays a role in the regulation of arterial vasomotor tone. Impairment of the vascular endothelium may result in disintegration of the blood vessel wall and leakage of fluids from the blood into the extracellular matrix, compromising organ function. Studies addressing the vascular toxicity of certain chemotherapeutic agents indicated that they were more toxic to endothelial cells than to tumor cells.

G protein coupled receptors for C3a are expressed in human mast cell lines, differentiated CD34+ -derived primary human mast cells as well as skin mast cells. C3a induces Ca2+ mobilization, causes substantial degranulation and chemokine generation in human mast cells via the activation of Gi-family of G proteins. Removal of potential phosphorylation sites within the carboxyl terminus of C3aR leads to more robust degranulation when compared to wildtype receptors. These findings are consistent with the idea that, as in many other cell types, receptor phosphorylation desensitizes C3aR expressed in mast cells. Agonist occupied GPCRs are phosphorylated by a family of protein kinases, collectively known as G protein coupled receptor kinases. Of the seven known GRKs, four are expressed LY2835219 ubiquitously. It is well established that GPCR phosphorylation by GRKs leads to the recruitment of b-arrestin, which results in receptor desensitization and internalization. However, the role of specific GRKs on receptor regulation has only been appreciated recently. Studies with siRNA-mediated knockdown of GRKs in HEK293 cells have shown that agonist-induced phosphorylation of angiotensin II type 1A receptor and V2 vasopressin receptors are predominantly mediated by GRK2 and GRK3. Furthermore, knockdown of these GRKs attenuated both agonist-induced b-arrestin recruitment and receptor desensitization. In addition to desensitization, receptor phosphorylation by GRKs leads to the activation of extracellular signal-regulated kinases in a b-arrestin-dependent manner. In HEK293 cells, knockdown of GRK5 and GRK6 inhibits angiotensin II and vasopressin-induced b-arrestin-dependent ERK1/2 phosphorylation. These findings suggest that for angiotensin type IA and vasopressin receptors, agonist-induced receptor phosphorylation by GRK2/GRK3 leads to receptor desensitization but their phosphorylation by GRK5/GRK6 promotes b-arrestin-dependent ERK1/2 phosphorylation. However, for the chemokine receptor CXCR4, GRK2/GRK6 are involved in receptor desensitization whereas GRK3/GRK6 play an important role in positively regulating ERK1/2 activation. In transfected COS cells, overexpression of GRK2, GRK3, GRK5 or GRK6 results in enhancement of agonist-induced C3aR phosphorylation. Our previous studies in a transfected mast cell line, RBL-2H3 indicated that GRK2 may participate in C3aR desensitization. However, the roles of other GRKs on the regulation of receptor function in mast cells remain unknown.

Recent studies have further shown that IRF4 is critical for the class-switch recombination by inducing activation induced deaminase and for germinal center reaction by downregulating Bcl6. IRF4 has been found to induce c-Myc expression in multiple MDV3100 myeloma cells and is critical for their survival and expansion. Finally, IRF4 can induce the expression of Fas apoptosis inhibitory molecule to regulate mature B cell survival and apoptosis. Given its role as a critical transcriptional regulator that limits pre-B cell expansion and promotes pre-B cell differentiation, it is reasonable to assume that IRF4 may function as a tumor suppressor against pre-B cell transformation. Indeed, a previous study has shown that IRF4 functions as a tumor suppressor to inhibit BCR/ABL oncogene induced B cell acute lymphoblastic leukemia. In addition, mice deficient for both IRF4 and IRF8 develop lymphoblastic leukemia. Although IRF4 can suppress BCR/ABL induced B cell transformation, the molecular mechanism by which IRF4 exerts its function remains unclear. In this report, we assessed the role of IRF4 in c-Myc oncogene induced B cell transformation by breeding IRF4 deficient mice with EmMyc transgenic mice. In the EmMyc mice, the expression of c-Myc oncogene is driven by immunoglobulin heavy chain enhancers and is predominantly found in the B cells. EmMyc transgenic mice mainly develop two types of leukemia/ lymphoma: pro/pre-B derived and mature B cell derived and the majority of the EmMyc mice succumb to disease within 5 to 6 months of age. It has been shown that the leukemogenesis of EmMyc mice can be modulated by oncogenes and tumor suppressor genes and thus, EmMyc mice have been widely used as an animal model to assess the role of potential oncogenes or tumor suppressor genes in B cell transformation. In this report, we show that c-Myc induced leukemia was greatly accelerated in the IRF4 heterozygous mutant mice. Moreover, we provided evidence that IRF4 functions as a classical tumor suppressor gene to inhibit c-Myc induced leukemogenesis. The transforming growth factor-b signaling pathway plays an important role in controlling proliferation, differentiation, and other cellular processes including the growth of ovarian surface epithelial cell. Dysregulation of TGFb signaling is frequently observed in epithelial ovarian cancer and may be crucial to EOC development. The effects of TGFb are mediated by three TGFb ligands — TGFb1, TGFb2 and TGFb3, acting through TGFb type 1 and type 2 receptors. TGFBR2 is the specific receptor for TGFb ligands.

Palbociclib clinical trial between strains with different pfhrp2 sequence. Control of transcription is believed to be under the influence of various regulatory systems, many of which are incompletely understood in Plasmodia. It is clear that transcription patterns vary between genetically distinct parasites. The 59 untranslated region of genes may contain regulatory elements that interact with promoter region elements to regulate transcription, or influence mRNA stability or survival. The 39 UTR may also have an important role n regulation of gene function. Although not investigated in this study, different parasite lines with different pfhrp2, or even identical coding sequences may differ in their 59 UTR and 39 UTR sequences, resulting in different levels of transcription. Epigenetic mechanisms may also significantly affect transcription. Changes in chromatin structure may profoundly influence the relationship between promoter and transcription factors. Nucleosome-free regions found at transcription start sites and core promoters are strongly associated with high levels of gene expression in intraerythrocytic stages. It is therefore possible that epigenetic factors play a role in pfhrp2 and pfhrp3 transcription. It should be noted that the levels of pfhrp2 and pfhrp3 transcripts and PfHRP protein measured in this study constitute the amounts of transcript or protein present at that timepoint, reflecting the combined result of transcription and degradation of the target. For transcripts, post-transcriptional control mechanisms including mRNA stability and decay may contribute significantly to the variation in the amount of transcripts present. mRNA translation efficiency can also be influenced by a range of factors. Histone 396–494 of pfhrp3 may play a role in mRNA stability. Variation in binding factor sequences in the 59 and 39 UTR may also exert a significant influence on mRNA stability and translation. Likewise, changes to the transcription start site may regulate the translation efficiency of a given gene. In all strains tested in this study, we observed that the level of pfhrp2 transcripts was always higher than that of pfhrp3. This could be a consequence of the promoter for pfhrp2 being stronger, or as a result of a slower decay of pfhrp2 transcripts. A 59 flanking region of pfhrp3 has been extensively used in transfection studies as a promoter for reporter gene expression, paired with a 39 flanking region of pfhrp2 as a terminator sequence. However, there is no report of using the pfhrp2 promoter for transfection, thus precluding a comparison of the two promoters.

It might also be a marker predicting subsequent development of invasive breast cancer. One of the well-studied functions of the HA and HAase system is the generation of angiogenic HA fragments. These angiogenic HA fragments have been shown to induce endothelial cell proliferation, migration, and adhesion. The secretion of HAase by tumor cells has been shown to induce angiogenesis. Angiogenic HA fragments are present in the urine of grade 2 and 3 bladder cancer patients, suggesting that the HA and HYAL1 system is active in bladder cancer. The HYAL1 and HYAL2 are widely distributed and degrade high MW HA in collaboration with CD44. We previously demonstrated that knockdown of HYAL1 expression in breast cancer cells resulted in decreased angiogenesis. In this study, we showed that upregulation of HYAL1 expression induced higher angiogenesis in vitro and in vivo. This was in accordance with previous reports that HYAL1 over-expression increased MVD in rat colon carcinoma xenografts, as well as the correlation of HYAL1 with MVD in bladder tumor. Which suggests that HYAL1 promotes tumor angiogenesis might be a general effect. Further studies characterizing this in other cancer models would be interest. At present, whether HAase is a tumor promoter or a repressor has been Z-VAD-FMK inhibitor controversial. The results presented in this study showed that forcing HYAL1 expression promoted tumor growth, invasion and angiogenesis supporting its role as a tumor promoter. HYAL1 levels in various cancers were associated with high-grade invasive tumors. However, Jacobson et al. found that the overexpression of HYAL1 by cDNA transfection in a rat colon carcinoma line decreased tumor growth, although the tumors were angiogenic. HYAL1 and HYAL2 have been identified to inhibit lung and renal carcinoma cell growth in vivo but not in vitro. Nykopp TK, et al found that HYAL1 and HYAL2 were coexpressed and significantly downregulated in endometrioid endometrial cancer and correlated with the accumulation of HA. The controversy surrounding HAase as a tumor promoter or a suppressor was recently explained by Lokeshwar et al. Selection of cells for expression of different HYAL1 levels showed that cells expressing amounts found in tumor tissues and cells promote tumor growth, invasion and angiogenesis. In contrast, cells with HAase levels exceeding 100 milliunits/106 cells, exhibit reduced tumor incidence and growth due to induction of apoptosis. Therefore, levels in genitourinary tumors are consistent with tumor cell derived HAase acting mainly as a tumor promoter.