Cross-protection and cross-neutralization capacity of ancestral and VOC-matched SARS-CoV-2 adenoviral vector-based vaccines.

COVID-19 vaccines were originally designed based on the ancestral Spike protein, but immune escape of emergent Variants of Concern (VOC) jeopardized their efficacy, warranting variant-proof vaccines. Here, we used preclinical rodent models to establish the cross-protective and cross-neutralizing capacity of adenoviral-vectored vaccines expressing VOC-matched Spike. CoroVaxG.3-D.FR, matched to Delta Plus Spike, displayed the highest levels of nAb to the matched VOC and mismatched variants. Cross-protection against viral infection in aged K18-hACE2 mice showed dramatic differences among the different vaccines. While Delta-targeted vaccines fully protected mice from a challenge with Gamma, a Gamma-based vaccine offered only partial protection to Delta challenge. Administration of CorovaxG.3-D.FR in a prime/boost regimen showed that a booster was able to increase the neutralizing capacity of the sera against all variants and fully protect aged K18-hACE2 mice against Omicron BA.1, as a BA.1-targeted vaccine did. The neutralizing capacity of the sera diminished in all cases against Omicron BA.2 and BA.5. Altogether, the data demonstrate that a booster with a vaccine based on an antigenically distant variant, such as Delta or BA.1, has the potential to protect from a wider range of SARS-CoV-2 lineages, although careful surveillance of breakthrough infections will help to evaluate combination vaccines targeting antigenically divergent variants yet to emerge.

CREB3L1-mediated functional and structural adaptation of the secretory pathway in hormone-stimulated thyroid cells.

Many secretory cells increase the synthesis and secretion of cargo proteins in response to specific stimuli. How cells couple increased cargo load with a coordinate rise in secretory capacity to ensure efficient transport is not well understood. We used thyroid cells stimulated with thyrotropin (TSH) to demonstrate a coordinate increase in the production of thyroid-specific cargo proteins and ER-Golgi transport factors, and a parallel expansion of the Golgi complex. TSH also increased expression of the CREB3L1 transcription factor, which alone caused amplified transport factor levels and Golgi enlargement. Furthermore, CREB3L1 potentiated the TSH-induced increase in Golgi volume. A dominant-negative CREB3L1 construct hampered the ability of TSH to induce Golgi expansion, implying that this transcription factor contributes to Golgi expansion. Our findings support a model in which CREB3L1 acts as a downstream effector of TSH to regulate the expression of cargo proteins, and simultaneously increases the synthesis of transport factors and the expansion of the Golgi to synchronize the rise in cargo load with the amplified capacity of the secretory pathway.

Synthetic Tumor-Specific Promoters for Transcriptional Regulation of Viral Replication.

Here we describe a collection of methods that have been adapted to isolate and modify tumor-specific promoters (TSPs ) to drive viral replication for cancer therapy and other uses. We will describe as examples the secreted protein acidic and rich in cysteine (SPARC ) and the protease-activated receptor-1 (PAR-1) promoter. We outline strategies to select appropriate TSPs using bioinformatics resources and the methods utilized in their subsequent cloning, assessment of transcriptional activity, and their use in conditionally replicative oncolytic adenoviruses .

Improvement of bovine semen quality by removal of membrane-damaged sperm cells with DNA aptamers and magnetic nanoparticles.

In cattle, cryopreservation of semen and sex-sorting kill up to 50% of spermatozoa and decrease the success of assisted insemination (AI). Therefore, significant efforts are being carried out to improve the quality of semen prior to AI. In this work we used the Cell-SELEX technique to select single strand DNA aptamers able to recognize with high affinity and specificity damaged sperm cells generated by heat-treatment. We first isolated aptamers with a conserved two motifs of 6 nucleotides of length that bind to the membrane of heat-treated spermatozoa. Then, we used synthetic biotin-labeled aptamers containing the conserved motif to recognize membrane-damaged cells and separate them from viable cells by the use of avidin-coated superparamagnetic iron oxide nanoparticles (SPION). This procedure improved the quality of semen by significantly increasing the percentage of healthy sperm cells without affecting the rate of blastocyst cleavage. This technique was successfully applied to both unsorted and sex-sorted sperm suspension.

Therapeutic improvement of a stroma-targeted CRAd by incorporating motives responsive to the melanoma microenvironment.

We have previously designed a conditionally replicative oncolytic adenovirus (CRAd) named Ad-F512 that can target both the stromal and the malignant melanoma cell compartments. The replication capacity of this CRAd is driven by a 0.5-Kb SPARC promoter fragment (named F512). To improve CRAd's efficacy, we cloned into F512 motives responsive to hypoxia (hypoxia-responsive element (HRE)) and inflammation (nuclear factor kappa B) to obtain a chimeric promoter named κBF512HRE. Using luciferase as a reporter gene, we observed 10-15-fold increased activity under hypoxia and 10-80-fold induction upon tumor necrosis factor-α addition. We next constructed a CRAd (Ad-κBF512HRE) where E1A activity was under κBF512HRE regulation. Treatment of nude mice harboring established tumors made of a mix of SB2 melanoma cells and WI-38 fibroblasts with Ad-κBF512HRE led to the complete elimination of tumors in 100% of mice (8/8). Moreover, Ad-5/3-κBF512HRE, a viral variant pseudotyped with a chimeric 5/3 fiber, exerted a strong lytic effect on CAR-negative melanoma cells and was highly effective in vivo on established tumors made of melanoma cells and WI-38 fibroblasts, leading to the complete elimination of 4/5 tumors. These results indicate that this improved stroma-targeted oncolytic adenovirus can override the resistance of melanoma tumors and might become of significant importance for melanoma therapeutics.

A tumor-stroma targeted oncolytic adenovirus replicated in human ovary cancer samples and inhibited growth of disseminated solid tumors in mice.

Targeting the tumor stroma in addition to the malignant cell compartment is of paramount importance to achieve complete tumor regression. In this work, we modified a previously designed tumor stroma-targeted conditionally replicative adenovirus (CRAd) based on the SPARC promoter by introducing a mutated E1A unable to bind pRB and pseudotyped with a chimeric Ad5/3 fiber (Ad F512v1), and assessed its replication/lytic capacity in ovary cancer in vitro and in vivo. AdF512v1 was able to replicate in fresh samples obtained from patients: (i) with primary human ovary cancer; (ii) that underwent neoadjuvant treatment; (iii) with metastatic disease. In addition, we show that four intraperitoneal (i.p.) injections of 5 × 10(10) v.p. eliminated 50% of xenografted human ovary tumors disseminated in nude mice. Moreover, AdF512v1 replication in tumor models was enhanced 15-40-fold when the tumor contained a mix of malignant and SPARC-expressing stromal cells (fibroblasts and endothelial cells). Contrary to the wild-type virus, AdF512v1 was unable to replicate in normal human ovary samples while the wild-type virus can replicate. This study provides evidence on the lytic capacity of this CRAd and highlights the importance of targeting the stromal tissue in addition to the malignant cell compartment to achieve tumor regression.

A specific subpopulation of mesenchymal stromal cell carriers overrides melanoma resistance to an oncolytic adenovirus.

The homing properties of mesenchymal stromal cells (MSCs) toward tumors turn them into attractive tools for combining cell and gene therapy. The aim of this study was to select in a feasible way a human bone marrow-derived MSC subpopulation that might exhibit a selective ability to target the tumor mass. Using differential in vitro adhesive capacities during cells isolation, we selected a specific MSC subpopulation (termed MO-MSCs) that exhibited enhanced multipotent capacity and increased cell surface expression of specific integrins (integrins α2, α3, and α5), which correlated with an enhanced MO-MSCs adhesiveness toward their specific ligands. Moreover, MO-MSCs exhibited a higher migration toward conditioned media from different cancer cell lines and fresh human breast cancer samples in the presence or not of a human microendothelium monolayer. Further in vivo studies demonstrated increased tumor homing of MO-MSCs toward established 578T and MD-MBA-231 breast cancer and A375N melanoma tumor xenografts. Tumor penetration by MO-MSCs was highly dependent on metallopeptidases production as it was inhibited by the specific inhibitor 1,10 phenantroline. Finally, systemically administered MO-MSCs preloaded with an oncolytic adenovirus significantly inhibited tumor growth in mice harboring established A375N melanomas, overcoming the natural resistance of the tumor to in situ administration of the oncolytic adenovirus. In summary, this work characterizes a novel MSC subpopulation with increased tumor homing capacity that can be used to transport therapeutic compounds.

A novel A33 promoter-based conditionally replicative adenovirus suppresses tumor growth and eradicates hepatic metastases in human colon cancer models.

PURPOSE: A33 antigen is a membrane-bound protein expressed in intestinal epithelium that is overexpressed in 95% of primary and metastatic colorectal carcinomas but is absent in most epithelial tissues and tumor types. We hypothesized that A33 promoter might be useful in the design of a conditionally replicative adenovirus for the treatment of colorectal cancer (CRC). EXPERIMENTAL DESIGN: We cloned an A33 promoter fragment (A33Pr) that extends from -105 to +307 bp. Using luciferase activity as a reporter gene, we showed that A33Pr was active in CRC cell lines. We next constructed a conditionally replicative adenovirus named AV22EL where E1A was placed under the control of A33Pr. The tumor-specific oncolytic effect of AV22EL was investigated both in vitro and in vivo. RESULTS: AV22EL induced specific in vitro lysis of human CRC cell lines that expressed A33 and have negligible lytic capacity on cells that lacked or had minimal A33 expression, including normal human colonic cells. In vivo, a marked reduction of tumor growth and increased long-term survival rates were observed in nude mice xenografted with s.c. CRC tumors. Combination with 5-fluorouracil induced an additive effect in vitro with no toxic effects in vivo. Remarkably, AV22EL completely eliminated established hepatic metastases in >90% of mice and restored hepatic function according to biochemical parameters. Its systemic administration induced E1A expression only in the hepatic metastasis but not in normal organs. CONCLUSIONS: These data show that AV22EL is a stringently regulated and potent oncolytic agent for the treatment of CRC.

Tumor associated stromal cells play a critical role on the outcome of the oncolytic efficacy of conditionally replicative adenoviruses.

The clinical efficacy of conditionally replicative oncolytic adenoviruses (CRAd) is still limited by the inefficient infection of the tumor mass. Since tumor growth is essentially the result of a continuous cross-talk between malignant and tumor-associated stromal cells, targeting both cell compartments may profoundly influence viral efficacy. Therefore, we developed SPARC promoter-based CRAds since the SPARC gene is expressed both in malignant cells and in tumor-associated stromal cells. These CRAds, expressing or not the Herpes Simplex thymidine kinase gene (Ad-F512 and Ad(I)-F512-TK, respectively) exerted a lytic effect on a panel of human melanoma cells expressing SPARC; but they were completely attenuated in normal cells of different origins, including fresh melanocytes, regardless of whether cells expressed or not SPARC. Interestingly, both CRAds displayed cytotoxic activity on SPARC positive-transformed human microendothelial HMEC-1 cells and WI-38 fetal fibroblasts. Both CRAds were therapeutically effective on SPARC positive-human melanoma tumors growing in nude mice but exhibited restricted efficacy in the presence of co-administered HMEC-1 or WI-38 cells. Conversely, co-administration of HMEC-1 cells enhanced the oncolytic efficacy of Ad(I)-F512-TK on SPARC-negative MIA PaCa-2 pancreatic cancer cells in vivo. Moreover, conditioned media produced by stromal cells pre-infected with the CRAds enhanced the in vitro viral oncolytic activity on pancreatic cancer cells, but not on melanoma cells. The whole data indicate that stromal cells might play an important role on the outcome of the oncolytic efficacy of conditionally replicative adenoviruses.

Expression of a suicidal gene under control of the human secreted protein acidic and rich in cysteine (SPARC) promoter in tumor or stromal cells led to the inhibition of tumor cell growth.

The successful use of transcriptional targeting for cancer therapy depends on the activity of a given promoter inside the malignant cell. Because solid human tumors evolve as a "cross-talk" between the different cell types within the tumor, we hypothesized that targeting the entire tumor mass might have better therapeutic effect. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein overexpressed in different human cancers malignant melanomas both in the malignant cells compartment as in the stromal one (fibroblasts and endothelial cells). We have shown that expression of the herpes simplex virus-thymidine kinase (TK) gene driven by the SPARC promoter in combination with ganciclovir inhibited human melanoma cell growth in monolayer as well as in multicellular spheroids. This inhibitory effect was observed both in homotypic spheroids composed of melanoma cells alone as well as in spheroids made of melanoma cells and stromal cells. Expression of the TK gene was also efficient to inhibit the in vivo tumor growth of established melanomas when TK was expressed either by the malignant cells themselves or by coadministered endothelial cells. Our data suggest that the use of therapeutic genes driven by SPARC promoter could be a valuable strategy for cancer therapy aiming to target all the cellular components of the tumor mass.