Search Results (12)

Background and Objectives: Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is involved in pancreatic cancer progression and is an attractive therapeutic target for pancreatic cancer. In this study, we evaluated the therapeutic efficacy of small-interfering RNA (siRNA) targeting CEACAM6 (siCEACAM6) and the CEACAM6-suppressive microRNA-29a (miR-29a) in a pancreatic ductal adenocarcinoma xenograft mouse model using pH-low insertion peptide (pHLIP) technology, which targets the acidic tumor microenvironment. Materials and Methods: The delivery vectors for siRNA and miRNA were constructed by conjugating the peptide nucleic acid forms of siCEACAM6 and miR-29a to a peptide with a pHLIP, enabling the transport of siRNA and miRNA across the plasma membrane. The tumor-suppressive effects of pHLIP-siCEACAM6 and pHLIP-miR-29a were assessed in vivo using a BALB/c xenograft mouse model with the injection of the CFPAC-1 human pancreatic ductal adenocarcinoma cell line. Results: The treatment of CFPAC-1 cells with pHLIP-siCEACAM6 and pHLIP-miR-29a under acidic pH conditions suppressed CEACAM6 expression and decreased cell viability. In a xenograft mouse model, the intravenous injection of pHLIP-siCEACAM6 and pHLIP-miR-29a suppressed tumor growth by up to 25.1% (p < 0.01) and 21.2% (p < 0.01), respectively, compared to the control mice treated with pHLIP-scr. Conclusions: Our results demonstrated the efficacy of the pHLIP-mediated delivery of siCEACAM6 and miR-29a as a promising therapeutic strategy in a pancreatic ductal adenocarcinoma xenograft mouse model. The pHLIP technology, which targets the acidic tumor microenvironment, represents an innovative approach to the delivery of small RNAs to pancreatic ductal adenocarcinoma cells, providing new potential strategies for pancreatic cancer treatment. Full article

The advent of pH-sensitive liposomes (pHLips) has opened new opportunities for the improved and targeted delivery of antitumor drugs as well as gene therapeutics. Comprising fusogenic dioleylphosphatidylethanolamine (DOPE) and cholesteryl hemisuccinate (CHEMS), these nanosystems harness the acidification in the tumor microenvironment and endosomes to deliver drugs effectively. pH-responsive liposomes that are internalized through endocytosis encounter mildly acidic pH in the endosomes and thereafter fuse or destabilize the endosomal membrane, leading to subsequent cargo release into the cytoplasm. The extracellular tumor matrix also presents a slightly acidic environment that can lead to the enhanced drug release and improved targeting capabilities of the nano-delivery system. Recent studies have shown that folic acid (FA) and iRGD-coated nanocarriers, including pH-sensitive liposomes, can preferentially accumulate and deliver drugs to breast tumors that overexpress folate receptors and αvβ3 and αvβ5 integrins. This study focuses on the development and characterization of 5-Fluorouracil (5-FU)-loaded FA and iRGD surface-modified pHLips (FA-iRGD-5-FU-pHLips). The novelty of this research lies in the dual targeting mechanism utilizing FA and iRGD peptides, combined with the pH-sensitive properties of the liposomes, to enhance selective targeting and uptake by cancer cells and effective drug release in the acidic tumor environment. The prepared liposomes were small, with an average diameter of 152 ± 3.27 nm, uniform, and unilamellar, demonstrating efficient 5-FU encapsulation (93.1 ± 2.58%). Despite surface functionalization, the liposomes maintained their pH sensitivity and a neutral zeta potential, which also conferred stability and reduced aggregation. Effective pH responsiveness was demonstrated by the observation of enhanced drug release at pH 5.5 compared to physiological pH 7.4. (84.47% versus 46.41% release at pH 5.5 versus pH 7.4, respectively, in 72 h). The formulations exhibited stability for six months and were stable when subjected to simulated biological settings. Blood compatibility and cytotoxicity studies on MDA-MB-231 and SK-BR3 breast cancer cell lines revealed an enhanced cytotoxicity of the liposomal formulation that was modified with FA and iRGD compared to free 5-FU and minimal hemolysis. Collectively, these findings support the potential of FA and iRGD surface-camouflaged, pH-sensitive liposomes as a promising drug delivery strategy for breast cancer treatment. Full article

The acidic extracellular microenvironment has become an effective target for diagnosing and treating tumors. A pH (low) insertion peptide (pHLIP) is a kind of peptide that can spontaneously fold into a transmembrane helix in an acidic microenvironment, and then insert into and cross the cell membrane for material transfer. The characteristics of the acidic tumor microenvironment provide a new method for pH-targeted molecular imaging and tumor-targeted therapy. As research has increased, the role of pHLIP as an imaging agent carrier in the field of tumor theranostics has become increasingly prominent. In this paper, we describe the current applications of pHLIP-anchored imaging agents for tumor diagnosis and treatment in terms of different molecular imaging methods, including magnetic resonance T1 imaging, magnetic resonance T2 imaging, SPECT/PET, fluorescence imaging, and photoacoustic imaging. Additionally, we discuss relevant challenges and future development prospects. Full article

pH (low) insertion peptides (pHLIPs) have been developed for cancer imaging and therapy targeting the acidic extracellular microenvironment. However, the characteristics of intratumoral distribution (ITD) of pHLIPs are not yet fully understood. This study aimed to reveal the details of the ITD of pHLIPs and their spatial relationship with other tumor features of concern. The fluorescent dye-labeled pHLIPs were intravenously administered to subcutaneous xenograft mouse models of U87MG and IGR-OV1 expressing α_Vβ₃ integrins (using large necrotic tumors). The α_Vβ₃ integrin-targeting Cy5.5-RAFT-c(-RGDfK-)₄ was used as a reference. In vivo and ex vivo fluorescence imaging, whole-tumor section imaging, fluorescence microscopy, and multiplexed fluorescence colocalization analysis were performed. The ITD of fluorescent dye-labeled pHLIPs was heterogeneous, having a high degree of colocalization with necrosis. A direct one-to-one comparison of highly magnified images revealed the cellular localization of pHLIP in pyknotic, karyorrhexis, and karyolytic necrotic cells. pHLIP and hypoxia were spatially contiguous but not overlapping cellularly. The hypoxic region was found between the ITDs of pHLIP and the cRGD peptide and the Ki-67 proliferative activity remained detectable in the pHLIP-accumulated regions. The results provide a better understanding of the characteristics of ITD of pHLIPs, leading to new insights into the theranostic applications of pHLIPs. Full article

Nanomedicine has been, to a certain degree, a success story in the development of superior anticancer therapies. However, there are tumors that remain a huge challenge for nanoformulations, for instance, brain tumors such as glioblastoma, the most common and aggressive brain tumor. To utilize the fact that such tumors are characterized by an acidic extracellular environment, we selected pH-responsive liposomes as a potential drug delivery system for superior delivery to GBM. Liposomes comprising PEGylated lipid of two chain lengths with encapsulated fluorescent marker calcein were characterized and challenged against non-PEGylated vesicles. The in vitro calcein release from three liposomal formulations (<200 nm), namely non-PEGylated (pH-Lip) and PEGylated, pH-Lip–PEG750, and pH-Lip–PEG2000, was followed at three pH conditions to prove the pH-responsiveness. The intracellular delivery of a liposomally encapsulated marker was determined in GL261 glioblastoma cell lines in vitro using both flow cytometry and confocal microscopy. The inclusion of PEG2000 within liposomal formulation resulted in reduced in vitro pH-responsiveness compared to pH-Lip and pH-Lip750. All three pH-responsive liposomal formulations improved intracellular uptake in GL261 cells compared to non-pH-responsive liposomes, with negligible differences regarding PEG length. The proposed formulations should be further evaluated in glioblastoma models. Full article

Decades of evidence suggest that alterations in the adhesion properties of neoplastic cells endow them with an invasive and migratory phenotype. Tight junctions (TJs) are present in endothelial and epithelial cells. Tumors arise from such tissues, thus, the role of TJ proteins in the tumor microenvironment is highly relevant. In the TJ, junctional adhesion molecules (JAM) play a key role in assembly of the TJ and control of cell–cell adhesion. Reprogramming of immune cells using chimeric antigen receptors (CAR) to allow for target recognition and eradication of tumors is an FDA approved therapy. The best-studied CAR-T cells recognize CD19, a B-cell surface molecule. CD19 is not a unique marker for tumors, liquid or solid. To address this limitation, we developed a biologic containing three domains: (1) pH-low-insertion peptide (pHLIP), which recognizes the low pH of the cancer cells, leading to the insertion of the peptide into the plasma membrane. (2) An extracellular domain of JAM proteins that fosters cell–cell interactions. (3) CD19 to be targeted by CAR-T cells. Our modular design only targets cancer cells and when coupled with anti-CD19 CAR-T cells, it decreases proliferation and metastasis in at least two cancer cell lines. Full article

The delivery of cancer therapeutics can be limited by pharmacological issues such as poor bioavailability and high toxicity to healthy tissue. pH-low insertion peptides (pHLIPs) represent a promising tool to overcome these limitations. pHLIPs allow for the selective delivery of agents to tumors on the basis of pH, taking advantage of the acidity of the hypoxic tumor microenvironment. This review article highlights the various applications in which pHLIPs have been utilized for targeting and treating diseases in hypoxic environments, including delivery of small molecule inhibitors, toxins, nucleic acid analogs, fluorescent dyes, and nanoparticles. Full article

The physical description of the atmosphere’s general circulation over Northern South America and Meso-America deserves a more comprehensive explanation. This work presents the Pacific coast of Colombia as the rainiest place on Earth, with annual rainfall averaging 5000 to 13,000 mm, and record values as high as 13,159 mm for the location of Puerto López (${77}^{\circ }{14}^{\prime }$ W, $2^{\circ }{50}^{\prime }$ N). Using information from the ECMWF ERA-40 Atlas and ERA-Interim Reanalysis, we describe the existence of a concentrated diabatic heating source due to condensation and the main features of its related circulation over Northern South America and Meso-America. For simplicity, we used the analytical solution of the Phlips-Gill Model to diagnose the main flow patterns. Results show that the diabatic source over western Colombia generates equatorial trapped Rossby-Kelvin waves, which dominate the low-level circulation. A Kelvin wave explains the low-level easterly flows over the Tropical Atlantic Ocean, the Caribbean Sea, the Venezuelan-Colombian Llanos, and the Northern Amazon Basin. This circulation is analogous to a Walker cell. To the west, two cyclonic flows and strong westerly winds are present in Meso-America and the far eastern Pacific because planetary waves propagate there. A slight asymmetry in the equator’s diabatic heating location is responsible for the intense low-level pressure over Panama. The vertical velocity over the source area induces vortex tube stretching, and zonal mean flow excites a mixed wave and a northward flow. Full article

Red and blue light have great effects on physiological processes and growth of plants. In this experiment, we investigated the physiological and growth response of pepper (Capsicum annuum L.) to supplementary red:blue (4:1) light for 1 h (T1), 3 h (T2), and 5 h (T3), and the full-spectrum light-emitting diodes, LEDs, as control (CK). Thirty-day-old seedlings were grown under these treatments for 20 days in a climate-controlled room before data measurement. The results showed that the light treatments significantly (p < 0.05) affected the photosynthesis and growth indexes as well as gene expression in the pepper seedlings. Plants under T2 generally had better performance in terms of seedling growth. A total of 124, 1283, and 1091 differentially expressed genes were found in CK vs. T1, CK vs. T2, and CK vs. T3, respectively. Among the treatments, T2 in comparison with CK had 705 upregulated and 578 downregulated differentially expressed genes (DEGs). We also found that CPRF2, Paggis, HLIPS, GIGANTEA, LSH1, and FTSH genes were expressed differently under the various light treatments. Based on GeneOntology (GO) enrichment analysis, DEGs were significantly enriched on 15 GO terms of which xyloglucan:xyloglucosyl transferase activity and apoplastic, cellular polysaccharide metabolic, and cellular carbohydrate metabolic processes were closely related to light responses. A total of 96 genes that are related to plant–pathogen interaction, zeatin biosynthesis, plant hormone signal transduction, and wax/cutin/suberine biosynthesis which are involved in the pathway of light reaction in plants were significantly enriched in T2 plants compared with plants under CK. The application of red:blue light at 4:1 for 3 h improved the growth of pepper seedlings better than the other treatments and this can be tested under the Chinese Solar Greenhouse condition. Full article

The development of novel theranostic nanovectors is of particular interest in treating formidable diseases (e.g., cancers). Herein, we report a new tumor-targetable theranostic agent based on core crosslinked (CCL) micelles, possessing tumor targetable moieties and fluorescence and magnetic resonance (MR) dual imaging modalities. An azide-terminated diblock copolymer, N₃-POEGMA-b-P(DPA-co-GMA), was synthesized via consecutive atom transfer radical polymerization (ATRP), where OEGMA, DPA, and GMA are oligo(ethylene glycol)methyl ether methacrylate, 2-(diisopropylamino)ethyl methacrylate, and glycidyl methacrylate, respectively. The resulting diblock copolymer was further functionalized with DOTA(Gd) (DOTA is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakisacetic acid) or benzaldehyde moieties via copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) chemistry, resulting in the formation of DOTA(Gd)-POEGMA-b-P(DPA-co-GMA) and benzaldehyde-POEGMA-b-P(DPA-co-GMA) copolymers. The resultant block copolymers co-assembled into mixed micelles at neutral pH in the presence of tetrakis[4-(2-mercaptoethoxy)phenyl]ethylene (TPE-4SH), which underwent spontaneous crosslinking reactions with GMA residues embedded within the micellar cores, simultaneously switching on TPE fluorescence due to the restriction of intramolecular rotation. Moreover, camptothecin (CPT) was encapsulated into the crosslinked cores at neutral pH, and tumor-targeting pH low insertion peptide (pHLIP, sequence: AEQNPIYWARYADWLFTTPLLLLDLALLVDADEGTCG) moieties were attached to the coronas through the Schiff base chemistry, yielding a theranostic nanovector with fluorescence and MR dual imaging modalities and tumor-targeting capability. The nanovectors can be efficiently taken up by A549 cells, as monitored by TPE fluorescence. After internalization, intracellular acidic pH triggered the release of loaded CPT, killing cancer cells in a selective manner. On the other hand, the nanovectors labeled with DOTA(Gd) contrast agents exhibited increased relaxivity (r₁ = 16.97 mM⁻¹·s⁻¹) compared to alkynyl-DOTA(Gd) small molecule precursor (r₁ = 3.16 mM⁻¹·s⁻¹). Moreover, in vivo MRI (magnetic resonance imaging) measurements revealed CCL micelles with pHLIP peptides exhibiting better tumor accumulation and MR imaging performance as well. Full article

Recent experiments in function mechanism study reported that a pH low-insertion peptide (pHLIP) can insert into a zwitterionic palmitoyloleoylphosphatidylcholine (POPC) lipid bilayer at acidic pH while binding to the bilayer surface at basic pH. However, the atomic details of the pH-dependent interaction of pHLIP with a POPC bilayer are not well understood. In this study, we investigate the detailed interactions of pHLIP with a POPC bilayer at acidic and basic pH conditions as those used in function mechanism study, using all-atom molecular dynamics (MD) simulations. Simulations have been performed by employing the initial configurations, where pHLIP is placed in aqueous solution, parallel to bilayer surface (system S), partially-inserted (system P), or fully-inserted (system F) in POPC bilayers. On the basis of multiple 200-ns MD simulations, we found (1) pHLIP in system S can spontaneously insert into a POPC bilayer at acidic pH, while binding to the membrane surface at basic pH; (2) pHLIP in system P can insert deep into a POPC bilayer at acidic pH, while it has a tendency to exit, and stays at bilayer surface at basic pH; (3) pHLIP in system F keeps in an α-helical structure at acidic pH while partially unfolding at basic pH. This study provides at atomic-level the pH-induced insertion of pHLIP into POPC bilayer. Full article

The recurrence of certain cancers remains quite high due to either incomplete surgical removal of the primary tumor or the presence of small metastases that are invisible to the surgeon. Near infrared (NIR) fluorescence imaging might improve surgical outcomes by providing sensitive, specific, and real-time visualization of normal and diseased tissues if agents can be found that discriminate between normal and diseased tissue and define tumor margins. We have developed a new approach for revealing tumor borders by using NIR fluorescently labeled pH Low Insertion Peptide (pHLIP) and have created a computational program for the quantitative assessment of tumor boundaries. The approach is tested in vivo by co-localization of GFP-tumors and NIR emission from the fluorescently labeled pHLIP, and it is found that boundaries are accurately reported and that sub-millimeter masses can be detected. Full article