An Assay to Assess Gap Junction Communication in Cell Lines

Breast cancers that disseminate to bone marrow acquire aggressive phenotypes through CX43-related tumor-stroma tunnels

Estrogen receptor-positive (ER+) breast cancer commonly disseminates to bone marrow, where interactions with mesenchymal stromal cells (MSCs) shape disease trajectory. We modeled these interactions with tumor-MSC co-cultures and used an integrated transcriptome-proteome-network-analyses workflow to identify a comprehensive catalog of contact-induced changes. Conditioned media from MSCs failed to recapitulate genes and proteins, some borrowed and others tumor-intrinsic, induced in cancer cells by direct contact. Protein-protein interaction networks revealed the rich connectome between "borrowed" and "intrinsic" components. Bioinformatics prioritized one of the borrowed components, CCDC88A/GIV, a multi-modular metastasis-related protein that has recently been implicated in driving a hallmark of cancer, growth signaling autonomy. MSCs transferred GIV protein to ER+ breast cancer cells (that lack GIV) through tunnelling nanotubes via connexin (Cx)43-facilitated intercellular transport. Reinstating GIV alone in GIV-negative breast cancer cells reproduced approximately 20% of both the borrowed and the intrinsic gene induction patterns from contact co-cultures; conferred resistance to anti-estrogen drugs; and enhanced tumor dissemination. Findings provide a multiomic insight into MSC→tumor cell intercellular transport and validate how transport of one such candidate, GIV, from the haves (MSCs) to have-nots (ER+ breast cancer) orchestrates aggressive disease states.

Fusogenic Liposomes for the Intracellular Delivery of Phosphocreatine

Background/Objective: Maintaining intracellular adenosine triphosphate (ATP) levels is essential for numerous cellular functions, including energy metabolism, muscle contraction, and nerve impulse transmission. ATP is primarily synthesized in mitochondria through oxidative phosphorylation. It is also generated in the cytosol under anaerobic conditions using phosphocreatine (PCr) as a phosphate donor to adenosine diphosphate. However, the intracellular delivery of exogenous PCr is challenging as it does not readily cross the plasma membrane. This complicates the use of PCr as a therapeutic agent to maintain energy homeostasis or to treat conditions like cerebral creatine deficiency syndrome (CDS), which results from defective creatine transporters. Methods: This study employs the use of fusogenic liposomes to deliver PCr directly into the cytosol, bypassing membrane impermeability issues. We engineered various 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-based fusogenic liposomes, incorporating phospholipids such as 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) in combination with phospholipid-aromatic dye components to facilitate membrane fusion and to enhance the delivery of the PCr cargo. Liposomal formulations were co-loaded with membrane-impermeable chromophores and PCr and studied on live cells using confocal microscopy. Conclusions: We demonstrated the successful intracellular delivery of these agents and observed a 23% increase in intracellular ATP levels in cells treated with PCr-loaded liposomes. This increase was not observed with free PCr, confirming the effectiveness of the liposome-based delivery system. Additionally, cell viability assays showed minimal toxicity from the liposomes. Our results indicate that fusogenic liposomes are a promising method for the delivery of PCr (and potentially other cell-impermeable therapeutic agents) to the cellular cytosol. The approach demonstrated here could be advantageous for treating energy-related disorders and improving cellular energy homeostasis.

Concurrent Oncolysis and Neurolesion Repair by Dual Gene-Engineered hNSCs in an Experimental Model of Intraspinal Cord Glioblastoma

Intramedullary spinal cord glioblastoma (ISCG) is lethal due to lack of effective treatment. We previously established a rat C6-ISCG model and the antitumor effect of F3.CD-TK, an hNSC line expressing CD and TK, via producing cytocidal 5FU and GCV-TP. However, the neurotherapeutic potential of this hNSC approach has remained uninvestigated. Here for the first time, cultured F3.CD-TK cells were found to have a markedly higher oncolytic effect, which was GJIC-dependent, and BDNF expression but less VEGF secretion than F3.CD. In Rowett athymic rats, F3.CD-TK (1.5 × 106 cells/10 µL × 2), injected near C6-ISCG (G55 seeding 7 days earlier: 10 K/each) and followed by q.d. (×5/each repeat; i.p.) of 5FC (500 mg/kg/5 mL/day) and GCV (25 mg/kg/1 mL/day), robustly mitigated cardiorespiratory, locomotor, and sensory deficits to improve neurofunction and overall survival compared to animals receiving either F3.CD or F3.CD-TK+F3.CD debris formula. The F3.CD-TK regimen exerted greater tumor penetration and neural inflammation/immune modulation, reshaped C6-ISCG topology to increase the tumor's surface area/volume ratio to spare/repair host axons (e.g., vGlut1+ neurites), and had higher post-prodrug donor self-clearance. The multimodal data and mechanistic leads from this proof-of-principle study suggest that the overall stronger anti-ISCG benefit of our hNSC-based GDEPT is derived from its concurrent oncolytic and neurotherapeutic effects.

Breast Cancers That Disseminate to Bone Marrow Acquire Aggressive Phenotypes through CX43-related Tumor-Stroma Tunnels

Estrogen receptor-positive (ER+) breast cancer commonly disseminates to bone marrow, where interactions with mesenchymal stromal cells (MSCs) shape disease trajectory. We modeled these interactions with tumor-MSC co-cultures and used an integrated transcriptome-proteome-network-analyses workflow to identify a comprehensive catalog of contact-induced changes. Conditioned media from MSCs failed to recapitulate genes and proteins, some borrowed and others tumor-intrinsic, induced in cancer cells by direct contact. Protein-protein interaction networks revealed the rich connectome between 'borrowed' and 'intrinsic' components. Bioinformatics prioritized one of the 'borrowed' components, CCDC88A /GIV, a multi-modular metastasis-related protein that has recently been implicated in driving a hallmark of cancer, growth signaling autonomy. MSCs transferred GIV protein to ER+ breast cancer cells (that lack GIV) through tunnelling nanotubes via connexin (Cx)43-facilitated intercellular transport. Reinstating GIV alone in GIV-negative breast cancer cells reproduced ∼20% of both the 'borrowed' and the 'intrinsic' gene induction patterns from contact co-cultures; conferred resistance to anti-estrogen drugs; and enhanced tumor dissemination. Findings provide a multiomic insight into MSC→tumor cell intercellular transport and validate how transport of one such candidate, GIV, from the haves (MSCs) to have-nots (ER+ breast cancer) orchestrates aggressive disease states.

Cell Surface Modification-Mediated Primary Intestinal Epithelial Cell Culture Platforms for Assessing Host-Microbiota Interactions

Background: Intestinal epithelial cells (IECs) play a crucial role in regulating the symbiotic relationship between the host and the gut microbiota, thereby allowing them to modulate barrier function, mucus production, and aberrant inflammation. Despite their importance, establishing an effective ex vivo culture method for supporting the prolonged survival and function of primary IECs remains challenging. Here, we aim to develop a novel strategy to support the long-term survival and function of primary IECs in response to gut microbiota by employing mild reduction of disulfides on the IEC surface proteins with tris(2-carboxyethyl)phosphine. Methods: Recognizing the crucial role of fibroblast-IEC crosstalk, we employed a cell surface modification strategy, establishing layer-to-layer contacts between fibroblasts and IECs. This involved combining negatively charged chondroitin sulfate on cell surfaces with a positively charged chitosan thin film between cells, enabling direct intercellular transfer. Validation included assessments of cell viability, efficiency of dye transfer, and IEC function upon lipopolysaccharide (LPS) treatment. Results: Our findings revealed that the layer-by-layer co-culture platform effectively facilitates the transfer of small molecules through gap junctions, providing vital support for the viability and function of primary IECs from both the small intestine and colon for up to 5 days, as evident by the expression of E-cadherin and Villin. Upon LPS treatment, these IECs exhibited a down-regulation of Villin and tight junction genes, such as E-cadherin and Zonula Occludens-1, when compared to their nontreated counterparts. Furthermore, the transcription level of Lysozyme exhibited an increase, while Mucin 2 showed a decrease in response to LPS, indicating responsiveness to bacterial molecules. Conclusions: Our study provides a layer-by-layer-based co-culture platform to support the prolonged survival of primary IECs and their features, which is important for understanding IEC function in response to the gut microbiota.

Tumor microenvironment responded naturally extracted FOF1-ATPase loaded chromatophores for antitumor therapy

Tumor microenvironment (TME) plays an important role in the growth, invasion, and metastasis of tumor cells. The pH of TME is more acidic in solid tumors than in normal tissues. Although targeted delivery in TME has progressed, the complex and expensive construction of delivery systems has limited their application. F_OF1-ATP synthase (F_OF1-ATPase) is a rotation molecular motor found in bacteria, chloroplasts, and mitochondria. Here, F_OF1-ATPase loaded chromatophores (chroma) isolated from thermophilic bacteria were extracted and utilized as a new delivery system targeting TME for the first time. Curcumin as model drug was successfully loaded by a filming-rehydration ultrasonic dispersion method to prepare a curcumin-loaded chroma delivery system (Cur-Chroma). The mobility and propensity distributions of Cur-Chroma reveal its specific pH-sensitive targeting driven by the transmembrane proton kinetic potential, demonstrating its distinct distribution in the TME and more favorable targeting delivery. Cellular uptake experiments indicated that Cur-Chroma entered cells through grid pathway-mediated endocytosis. In vivo studies have shown that Cur-Chroma can specifically target tumor tissue and effectively inhibit tumor growth with good safety. Curcumin's bioavailability and anti-tumor effects were significantly improved. These studies demonstrate that ATPase-loaded chromatophores are potentially ideal vehicles for anti-tumor drug delivery and have promising applications.

Modifying gap junction communication in cancer therapy

AIM

Drug delivery is crucial for therapeutic efficacy and gap junction communication channels (GJIC) facilitate movement within the tumour. Pro-drug activation, a modality of cancer therapy leads to Ganciclovir triphosphate (GCV-TP) incorporation into newly synthesized DNA resulting in cell death. The objective was to enhance, with Histone deacetylase inhibitors (HDACi) and All Trans Retinoic Acid (ATRA), GJIC, crucial for drug delivery, and with combination, abrogate the observed detrimental effect of Dexamethasone (DXM).

METHODS

Cell lines (NT8E, and HeLa) were pre-treated with Valproic Acid (VPA) (1 mM), 4 Phenyl Butyrate (4PB) (2 mM), ATRA (10 μM) and Dexamethasone (1 μM). Protein quantitated with the Bicinchoninic (BCA) assay for cell lysates, membrane and soluble fractions was assessed with Western blotting for Connexins (43, 26 and 32) and E-Cadherin. A qRT-PCR was done for CX 43-GJA1, CX 26-GJB2, CX 32-GJB1 and E-Cadherin, and normalized with Glyceraldehyde Phosphate dehydrogenase (GAPDH). Further, localization of Connexins (CX) and E-Cadherin, GJIC competence, pre-clinical in-vitro studies and the mechanism of cell death were evaluated.

RESULTS

There was no toxicity or change in growth patterns observed with the drugs. In both the cell lines CX 43 localized to the membrane whereas CX 32 and CX 26 were present but not membrane bound. E-Cadherin was present on the membrane in NT8E and completely absent in HeLa cells. Effects of HDACi, DXM and ATRA were seen on the expression of Connexins and E-Cadherin in both the cell lines. NT8E and HeLa cell lines showed enhanced GJIC with 4PB [30 %], VPA [36 %] and ATRA [54 %] with a 60 % increase in cytotoxicity and an abrogation of Dexamethasone inhibition on combination with VPA or ATRA.

CONCLUSION

An enhancement of GJIC function by HDACi and ATRA increased cytotoxicity and could be effective in the presence of Dexamethasone, when combined with ATRA or VPA.