Trop-2 inhibits prostate cancer cell adhesion to fibronectin through the β1 integrin-RACK1 axis.

Trop-2 is a transmembrane glycoprotein upregulated in several human carcinomas, including prostate cancer (PrCa). Trop-2 has been suggested to regulate cell-cell adhesion, given its high homology with the other member of the Trop family, Trop-1/EpCAM, and its ability to bind the tight junction proteins claudin-1 and claudin-7. However, a role for Trop-2 in cell adhesion to the extracellular matrix has never been postulated. Here, we show for the first time that Trop-2 expression in PrCa cells correlates with their aggressiveness. Using either shRNA-mediated silencing of Trop-2 in cells that endogenously express it, or ectopic expression of Trop-2 in cells that do not express it, we show that Trop-2 inhibits PrCa cell adhesion to fibronectin (FN). In contrast, expression of another transmembrane receptor, α(v) β(5) integrin, does not affect cell adhesion to this ligand. We find that Trop-2 does not modulate either protein or activation levels of the prominent FN receptors, β(1) integrins, but acts through increasing β(1) association with the adaptor molecule RACK1 and redistribution of RACK1 to the cell membrane. As a result of Trop-2 expression, we also observe activation of Src and FAK, known to occur upon β(1) -RACK1 interaction. These enhanced Src and FAK activities are not mediated by changes in either the activity of IGF-IR, which is known to bind RACK1, or IGF-IR\u27s ability to associate with β(1) integrins. In summary, our data demonstrate that the transmembrane receptor Trop-2 is a regulator of PrCa cell adhesion to FN through activation of the β(1) integrin-RACK1-FAK-Src signaling axis

Renal Function in Kidney and Liver Transplant Recipients After A 130-km Road Cycling Race

Background: A few patients, after receiving solid organ transplantation, return to performing various sports and competitions; however, at present, data no study had evaluated the effects of endurance cycling races on their renal function. Methods: Race times and short form (36) health survey questionnaires of 10 kidney transplant recipients (KTR) and 8 liver transplant recipients (LTR) transplanted recipients involved in a road cycling race (130 km) were compared with 35 healthy control subjects (HCS), also taking laboratory blood and urine tests the day before the race, at the end of the race, and 18 to 24 hours after competing. Results: The 3 groups showed similar race times (KTR, 5 hours 59 minutes \ub1 0 hours 39 minutes; LTR, 6 hours 20 minutes \ub1 1 hour 11 minutes; HCS, 5 hours 40 minutes \ub1 1 hour 28 minutes), similar short form (36) health survey scores, and similar trend of laboratory parameters which returned to baseline after 18 to 24 hours. After the race, there was an increase in creatinine (0.24 mg/dL; effect size [ES] = 0.78; P < 0.001), urea (22 mg/dL; ES = 1.42; P < 0.001), and a decrease of estimated glomerular filtration rate ( 1217 mL/min; ES = 0.85; P < 0.001). The increase of blood uric acid was more remarkable in HCS and KTR (2.3 mg/dL; ES = 1.39; P < 0.001). The KTR showed an increase of microalbuminuria (167.4 mg/L; ES = 1.20; P < 0.001) and proteinuria (175 mg/mL; ES = 0.97; P < 0.001) similar to LTR (microalbuminuria: 176.0 mg/L; ES = 1.26; P < 0.001; proteinuria: 213 mg/mL; ES = 1.18; P < 0.001), with high individual variability. The HCS had a nonsignificant increase of microalbuminuria (4.4 mg/L; ES = 0.03; P = 0.338) and proteinuria (59 mg/mL; ES = 0.33; P = 0.084). Conclusions: Selected and well-trained KTR and LTR patients can participate to an endurance cycling race showing final race times and temporary modifications of kidney function similar to those of HCS group, despite some differences related to baseline clinical conditions and pharmacological therapies. Patients involved in this study represent the upper limit of performance currently available for transplant recipients and cannot be considered representative of the entire transplanted population

Phylogenetic conservation of Trop-2 across species—rodent and primate genomics model anti-Trop-2 therapy for pre-clinical benchmarks

A phylogenetic conservation analysis of Trop-2 across vertebrate species showed a high degree of sequence conservation, permitting to explore multiple models as pre-clinical benchmarks. Sequence divergence and incomplete conservation of expression patterns were observed in mouse and rat. Primate Trop-2 sequences were found to be 95%–100% identical to the human sequence. Comparative three-dimension primate Trop-2 structures were obtained with AlphaFold and homology modeling. This revealed high structure conservation of Trop-2 (0.66 ProMod3 GMQE, 0.80–0.86 ± 0.05 QMEANDisCo scores), with conservative amino acid changes at variant sites. Primate TACSTD2/TROP2 cDNAs were cloned and transfectants for individual ORF were shown to be efficiently recognized by humanized anti-Trop-2 monoclonal antibodies (Hu2G10, Hu2EF). Immunohistochemistry analysis of Macaca mulatta (rhesus monkey) tissues showed Trop-2 expression patterns that closely followed those in human tissues. This led us to test Trop-2 targeting in vivo in Macaca fascicularis (cynomolgus monkey). Intravenously injected Hu2G10 and Hu2EF were well tolerated from 5 to 10 mg/kg. Neither neurological, respiratory, digestive, urinary symptoms, nor biochemical or hematological toxicities were detected during 28-day observation. Blood serum pharmacokinetic (PK) studies were conducted utilizing anti-idiotypic antibodies in capture-ELISA assays. Hu2G10 (t1/2 = 6.5 days) and Hu2EF (t1/2 = 5.5 days) were stable in plasma, and were detectable in the circulation up to 3 weeks after the infusion. These findings validate primates as reliable models for Hu2G10 and Hu2EF toxicity and PK, and support the use of these antibodies as next-generation anti-Trop-2 immunotherapy tools

Cancer-Homing CAR-T Cells and Endogenous Immune Population Dynamics

Chimeric antigen receptor (CAR) therapy is based on patient blood-derived T cells and natural killer cells, which are engineered in vitro to recognize a target antigen in cancer cells. Most CAR-T recognize target antigens through immunoglobulin antigen-binding regions. Hence, CAR-T cells do not require the major histocompatibility complex presentation of a target peptide. CAR-T therapy has been tremendously successful in the treatment of leukemias. On the other hand, the clinical efficacy of CAR-T cells is rarely detected against solid tumors. CAR-T-cell therapy of cancer faces many hurdles, starting from the administration of engineered cells, wherein CAR-T cells must encounter the correct chemotactic signals to traffic to the tumor in sufficient numbers. Additional obstacles arise from the hostile environment that cancers provide to CAR-T cells. Intense efforts have gone into tackling these pitfalls. However, we argue that some CAR-engineering strategies may risk missing the bigger picture, i.e., that a successful CAR-T-cell therapy must efficiently intertwine with the complex and heterogeneous responses that the body has already mounted against the tumor. Recent findings lend support to this model

IGF-IR promotes prostate cancer growth by stabilizing α5β1 integrin protein levels.

Dynamic crosstalk between growth factor receptors, cell adhesion molecules and extracellular matrix is essential for cancer cell migration and invasion. Integrins are transmembrane receptors that bind extracellular matrix proteins and enable cell adhesion and cytoskeletal organization. They also mediate signal transduction to regulate cell proliferation and survival. The type 1 insulin-like growth factor receptor (IGF-IR) mediates tumor cell growth, adhesion and inhibition of apoptosis in several types of cancer. We have previously demonstrated that β1 integrins regulate anchorage-independent growth of prostate cancer (PrCa) cells by regulating IGF-IR expression and androgen receptor-mediated transcriptional functions. Furthermore, we have recently reported that IGF-IR regulates the expression of β1 integrins in PrCa cells. We have dissected the mechanism through which IGF-IR regulates β1 integrin expression in PrCa. Here we report that IGF-IR is crucial for PrCa cell growth and that β1 integrins contribute to the regulation of proliferation by IGF-IR. We demonstrate that β1 integrin regulation by IGF-IR does not occur at the mRNA level. Exogenous expression of a CD4 - β1 integrin cytoplasmic domain chimera does not interfere with such regulation and fails to stabilize β1 integrin expression in the absence of IGF-IR. This appears to be due to the lack of interaction between the β1 cytoplasmic domain and IGF-IR. We demonstrate that IGF-IR stabilizes the β1 subunit by protecting it from proteasomal degradation. The α5 subunit, one of the binding partners of β1, is also downregulated along with β1 upon IGF-IR knockdown while no change is observed in the expression of the α2, α3, α4, α6 and α7 subunits. Our results reveal a crucial mechanistic role for the α5β1 integrin, downstream of IGF-IR, in regulating cancer growth

The multiverse nature of epithelial to mesenchymal transition

International audienceThe epithelial mesenchymal transition (EMT) program is defined as a cellular transition from an epithelial to a mesenchymal state. This process occurs to provide the cell with new phenotypic assets and new skills to perform complex processes. EMT is regulated at multilayer levels, including transcriptional control of gene expression, regulation of RNA splicing, and translational/post-translational control. Although transcriptional regulation by EMT-inducing transcription factors (EMT-TFs), including Zeb, Snail and Slug members, is generally considered the master step in this process, emerging data indicate that all these regulatory networks may have a role in the control of EMT. There is a sort of parallelism between the biological and still unrevealed EMT complexity and the cosmological hypothesis that sustains the universe may exist as a multiverse. The presence of different EMT transition states together with the occurrence of multiple layers of regulation support the idea that EMT is just one on many out there. Is the activation of a single layer of regulation sufficient to initiate the whole EMT program? Can we postulate the activation of different EMT "dimensions"? If we think about these layers as multiple separate "universes", various scenarios can be revealed