Biology subjects

Francisco, L. E.

Publications and source records attributed to Francisco, L. E..

3 recordsLinked to original sources

bioRxiv2022

An antibody-drug conjugate targeting GPR56 demonstrates efficacy in preclinical models of colorectal cancer

Antibody-drug conjugates (ADCs) have become an increasingly successful class of anticancer therapy, particularly within the past few years. Though ADCs are in clinical trials for colorectal cancer (CRC), a candidate has yet to be approved. CRC continues to be a leading cause of cancer-related death, emphasizing the need to identify novel target antigens for ADC development. GPR56, a member of the 7TM receptor family, is upregulated in colorectal tumors compared to normal tissues and located on the surface of CRC cells, making it a promising ADC target. Furthermore, high GPR56 expression occurs in tumors that are microsatellite stable, negative for the CpG methylator phenotype, and show chromosomal instability. We previously reported the generation of a high affinity GPR56-specific monoclonal antibody, 10C7, and we have now mapped the epitope to the C-terminal end of the extracellular domain, proximal to the GPCR proteolysis site. Here, we describe the development of a duocarmycin-conjugated 10C7 ADC. 10C7 co-internalized with GPR56 and trafficked to the lysosomes of CRC cells, which is critical for efficient ADC payload release. Evaluation of the ADC in a panel of CRC cell lines and tumor organoids with different levels of GPR56 expression showed the ADC selectively induced cytotoxicity at low nanomolar concentrations in a GPR56-dependent manner. A nontargeting control ADC showed minimal to no activity. Furthermore, GPR56 ADC exhibited significant antitumor efficacy against GPR56-expressing patient-derived xenograft models of CRC. This study provides rationale for the development of a GPR56-targeted ADC approach to potentially treat a large fraction of CRC patients.

cancer biology↗

bioRxiv2022

Loss of LGR5 through plasticity or gene ablation is associated with therapy resistance and enhanced MET-STAT3 signaling in colorectal cancer cells

Plasticity plays a significant role in colorectal tumor initiation, progression, and drug resistance. LGR5 is highly expressed in colorectal cancer (CRC) and marks functional cancer stem cells (CSCs). While LGR5+ CSCs are tumor-initiating, the majority of CRC cells that disseminate to seed metastases are LGR5-; however, reemergence of LGR5+ CSCs is required to drive metastatic outgrowth. LGR5+ CSCs have been shown to convert to LGR5- CRC cells in response to chemotherapies and this loss of LGR5 promotes a more drug-resistant phenotype. However, the molecular mechanisms that mediate plasticity remain elusive. In this study, we demonstrate conversion of LGR5+ CRC cells to an LGR5- state in response to chemotherapy, LGR5-targeted antibody-drug conjugates (ADCs), or LGR5 gene ablation, led to activation of STAT3. Further investigation revealed increased STAT3 activation occurred a result of increased MET activity. LGR5 overexpression decreased MET-STAT3 activity and sensitized CRC cells to therapy. STAT3 inhibition suppressed MET phosphorylation, while constitutively active STAT3 reduced LGR5 levels and increased MET activity, suggesting a potential feedback mechanism. Combination treatment of MET-STAT3 inhibitors with irinotecan or ADCs substantiated synergistic effects in vitro. In CRC xenografts, STAT3 inhibition combined with irinotecan enhanced tumor growth suppression and prolonged survival. These findings suggest a mechanism by which drug-resistant LGR5- CRC cells acquire a survival advantage through activation of MET-STAT3 and provide rationale for new treatment strategies that target CRC cell plasticity. SignificanceThis study reveals that transition of highly plastic LGR5+ CRC cells to a more drug-resistant LGR5- state involves activation of MET-STAT3 signaling and provides new insight into therapeutic strategies to combat plasticity.

cancer biology↗

bioRxiv2020

Cardiac Microlesions Form During Severe Bacteremic Enterococcus faecalis Infection

Enterococcus faecalis is a significant cause of hospital-acquired bacteremia. Herein, the discovery is reported that cardiac microlesions form during severe bacteremic E. faecalis infection in mice. The cardiac microlesions were identical in appearance to those formed by Streptococcus pneumoniae during invasive pneumococcal disease (IPD). However, E. faecalis does not encode the virulence determinants implicated in pneumococcal microlesion formation. Rather, disulfide bond forming protein DsbA was found to be required for E. faecalis virulence in a C. elegans model and was necessary for efficient cardiac microlesion formation. Furthermore, E. faecalis promoted cardiomyocyte apoptotic and necroptotic cell death at sites of microlesion formation. Additionally, loss of DsbA caused an increase in pro-inflammatory cytokines unlike the wild-type strain, which suppressed the immune response. In conclusion, we establish that E. faecalis is capable of forming cardiac microlesions and identify features of both the bacterium and the host response that are mechanistically involved. SUMMARYThis work presents the observation of cardiac microlesion formation during severe blood stream infection with Enterococcus faecalis in mice. Moreover, we identify the contribution of a novel enterococcal virulence determinant in modulating microlesion formation and the host immune response.

microbiology↗