We have previously reported that metastases from all malignancies are characterized by a core program of gene expression that suppresses extracellular matrix interactions, induces ...vascularization/tissue remodeling, activates the oxidative metabolism, and alters ion homeostasis. Among these features, the least elucidated component is ion homeostasis. Here we review the literature with the goal to infer a better mechanistic understanding of the progression-associated ionic alterations and identify the most promising drugs for treatment. Cancer metastasis is accompanied by skewing in calcium, zinc, copper, potassium, sodium and chloride homeostasis. Membrane potential changes and water uptake through Aquaporins may also play roles. Drug candidates to reverse these alterations are at various stages of testing, with some having entered clinical trials. Challenges to their utilization comprise differences among tumor types and the involvement of multiple ions in each case. Further, adverse effects may become a concern, as channel blockers, chelators, or supplemented ions will affect healthy and transformed cells alike.
The cytokine Osteopontin is a mediator of tumor progression and cancer metastasis. In 2006, we reported that (in addition to the full-length form -a) splice variants of Osteopontin (forms -b and -c) ...are produced selectively by transformed cells. Through June 2021, 36 PubMed-indexed journal articles have studied Osteopontin splice variants in various cancer patients.
Applying a categorical approach previously developed by us, here we conduct a meta-analysis of the pertinent literature. We supplement this with evaluation of the relevant entries in the TSVdb database, which focusses on splice variant expression, thus including the additional variants -4 and -5. The analysis covers 5886 patients across 15 tumors from the literature and 10,446 patients across 33 tumors from TSVdb.
The database yields positive results more frequently than the categorical meta-analysis. The two sources are in agreement on the elevation of OPN-a, OPN-b, and OPN-c in lung cancer and the elevation of OPN-c in breast cancer as compared to healthy tissue. Specific splice variants are associated with grade, stage, or patient survival pertaining to various cancers.
There are cases of persisting discrepancies, which require further investigation to clarify the Osteopontin splice variant utilization, so that their diagnostic, prognostic and potentially predictive potential can be brought to fruition.
Background
We previously reported that metastases are generally characterized by a core program of gene expression that activates tissue remodeling/vascularization, alters ion homeostasis, induces ...the oxidative metabolism, and silences extracellular matrix interactions. This core program distinguishes metastases from their originating primary tumors as well as from their destination host tissues. Therefore, the gene products involved are potential targets for anti‐metastasis drug treatment.
Methods
Because the silencing of extracellular matrix interactions predisposes to anoiks in the absence of active survival mechanisms, we tested inhibitors against the other three components.
Results
Individually, the low‐specificity VEGFR blocker pazopanib (in vivo combined with marimastat), the antioxidant dimethyl sulfoxide (or the substitute atovaquone, which is approved for internal administration), and the ionic modulators bumetanide and tetrathiomolybdate inhibited soft agar colony formation by breast and pancreatic cancer cell lines. The individual candidate agents have a record of use in humans (with limited efficacy when administered individually) and are available for repurposing. In combination, the effects of these drugs were additive or synergistic. In two mouse models of cancer (utilizing 4T1 cells or B16‐F10 cells), the combination treatment with these medications, applied immediately (to prevent metastasis formation) or after a delay (to suppress established metastases), dramatically reduced the occurrence of disseminated foci.
Conclusions
The combination of tissue remodeling inhibitors, suppressors of the oxidative metabolism, and ion homeostasis modulators has very strong promise for the treatment of metastases by multiple cancers.
Cytokine release syndromes represent a severe turn in certain disease states, which may be caused by several infections, including those with the virus SARS‐CoV‐2. This inefficient, even harmful, ...immune response has been associated with a broad release of chemokines. Although a cellular (type I) immune reaction is efficacious against viral infections, we noted a type I deficit in the cytokine patterns produced by cytokine storms of all reported etiologies. Agents including lipopolysaccharide (LPS, bacterial), anti‐CD3 (antibody) and a version of the prominent SARS‐CoV‐2 viral surface molecule, Spike Glycoprotein, were individually sufficient to induce IL‐6 and multiple chemokines in mice. They failed to upregulate the TH1 inducer cytokine Osteopontin, and the pathophysiologic triggers actually suppressed the PMA‐induced Osteopontin secretion from monocytic cells. Osteopontin administration partially reversed the chemokine elevation, more effectively so in a mouse strain with TH1 bias. Corroboration was obtained from the inverse correlation in the levels of IL‐6 and Osteopontin in plasma samples from acute COVID‐19 patients. We hypothesize that the inhibition of Osteopontin by SARS‐CoV‐2 Spike Glycoprotein or LPS represents an immune evasion mechanism employed by the pathogens of origin. The ensuing dysfunctional inflammatory response promotes a vicious cycle of amplification, resulting in a cytokine storm.
Lipopolysaccharide‐induced cytokine release syndrome and effect by Osteopontin.
Since the original description in 1996, the interaction between the cytokine osteopontin (OPN) and the homing receptor CD44 has been extensively studied in cancer, inflammation, bone remodeling, and ...various other conditions. Alternative splicing and extensive posttranslational modifications by both binding partners, as well as the possibility for lateral recruitment of additional membrane receptors or soluble co-ligands into a complex have left the exact molecular requirements for high-affinity OPN-CD44 binding unresolved. We now report that there is a moderate engagement between the unmodified molecules, which results in curved double-reciprocal plots for OPN titration, suggesting the existence of two binding sites or two binding conformations. Structural constraint of OPN, by immobilization or by addition of heparin, is required for its strong ligation of CD44. Prior literature provides evidence that heparin binding to OPN prompts the unfolding of a core element in the protein. This conformational adjustment may be essential for efficient CD44 interaction. The integrin α9β1 seems to compete with the OPN-CD44 engagement, while the integrin αVβ3 reflects additive binding, suggesting that the CD44 contact sites on OPN are downstream of the RGD motif but overlap with the SVVYGLR domain. Hyaluronate has no effect, placing the relevant domain on CD44 downstream of the N-terminus.
Age-related macular degeneration, precisely neovascular form, is the leading cause of vision loss and the key treatment includes intravitreal injections of anti-vascular endothelial growth factor ...(anti-VEGF) agents. A method to increase local concentration of drug at posterior segment of the eye and to reduce the frequency of intravitreal injections is an unmet need. Resveratrol, a naturally occurring antioxidant and anti-inflammatory polyphenol, was loaded in PLGA polymeric nanoparticles to study their sustained release property and effectiveness in reducing expression of VEGF protein
in vitro
. Nanoparticles were characterized using FTIR, DSC, size, encapsulation efficiency, TEM, and
in vitro
drug release studies. Using MTT assay, the cytotoxicity of formulation was evaluated on ARPE-19 cells. The cellular uptake and VEGF expression levels were also evaluated in
in vitro
settings. The optimized formulation had a particle size of 102.7 nm with − 47.30 mV of zeta potential. Entrapment efficiency was found to be 65.21%. The cell viability results suggested compatibility of developed formulation. Cellular uptake and VEGF expression levels for the formulated nanoparticles specified that the developed formulation showed potential cellular uptake and had displayed anti-angiogenic property by inhibiting VEGF expression
in vitro
. The results showed successful development of resveratrol-loaded nanoparticles which may be used for neovascular AMD treatment alone or in combination with anti-VEGF agents.
Metastasizing cells display a unique metabolism, which is very different from the Warburg effect that arises in primary tumors. Over short time frames, oxidative phosphorylation and ATP generation ...are prominent. Over longer time frames, mitochondrial biogenesis becomes a pronounced feature and aids metastatic success. It has not been known whether or how these two phenomena are connected. We hypothesized that Osteopontin splice variants, which synergize to increase ATP levels in deadherent cells, also increase the mitochondrial mass via the same signaling mechanisms. Here, we report that autocrine Osteopontin does indeed stimulate an increase in mitochondrial size, with the splice variant -c being more effective than the full-length form -a. Osteopontin-c achieves this via its receptor CD44v, jointly with the upregulation and co-ligation of the chloride-dependent cystine-glutamate transporter SLC7A11. The signaling proceeds through activation of the known mitochondrial biogenesis inducer PGC-1 (which acts as a transcription coactivator). Peroxide is an important intermediate in this cascade, but surprisingly acts upstream of PGC-1 and is likely produced as a consequence of SLC7A11 recruitment and activation. In vivo, suppression of the biogenesis-inducing mechanisms leads to a reduction in disseminated tumor mass. This study confirms a functional connection between the short-term oxidative metabolism and the longer-term mitochondrial biogenesis in cancer metastasis - both are induced by Osteopontin-c. The results imply possible mechanisms and targets for treating cancer metastasis.
Age-related macular degeneration (AMD) is a reason of severe vision loss worldwide. Pazopanib is a multitargeted tyrosine kinase inhibitor drug that can reduce neovascularization by mainly acting on ...vascular endothelial growth factor receptor (VEGFR). An intraocular injection to posterior segment of eye of anti-VEGF agent at present represents the cornerstone of therapies for AMD. However, challenges in targeting and delivering drug to eye's posterior segment well as difficulties arising from repetitive frequent intraocular injections, which requires novel drug delivery method. In this study, pazopanib loaded PLGA‐NPs were prepared and the studied formulation had particle size of 132.1 ± 1.4 nm with PDI of 0.125 ± 0.023 and 0.004 ± 0.13 mV for zeta potential. Entrapment efficiency was found 33.9 ± 2.5%. In vitro drug release study showed sustained drug lease. In vitro characterization in human retinal pigmented epithelial cell line described MTT assay, cellular uptake, wound scratch and anti-VEGF assay, which indicated that nanoparticles formulation had less toxicity, higher uptake, had superior anti-angiogenic potential and showed prolonged inhibition of VEGF activity. Therefore, pazopanib loaded PLGA nanoparticles were successfully developed, characterized and demonstrated its treatment of AMD.
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