Targeting PI3K in Cancer: Impact on Tumor Cells, Their Protective Stroma, Angiogenesis, and Immunotherapy

The PI3K pathway is hyperactivated in most cancers, yet the capacity of PI3K inhibitors to induce tumor cell death is limited. The efficacy of PI3K inhibition can also derive from interference with the cancer cells’ ability to respond to stromal signals, as illustrated by the approved PI3Kδ inhibitor Idelalisib in B-cell malignancies. Inhibition of the leukocyte-enriched PI3Kδ or PI3Kγ may unleash more potent anti-tumor T-cell responses, by inhibiting regulatory T-cells and immune-suppressive myeloid cells. Moreover, tumor angiogenesis may be targeted by PI3K inhibitors to enhance cancer therapy. Future work should therefore focus on the effects of PI3K inhibitors on the stroma, in addition to their direct effects on tumors. SIGNIFICANCE: The PI3K pathway extends beyond the direct regulation of cancer cell proliferation and survival. In B-cell malignancies, targeting PI3K purges the tumor cells from their protective microenvironment. Moreover, we propose that PI3K isoform-selective inhibitors may be exploited in the context of cancer immunotherapy and by targeting angiogenesis to improve drug and immune cell deliver

The Reproducibility of Ultrasonographic Findings of Rectosigmoid Endometriosis Among Examiners With Different Level of Expertise

Objective: To analyze the reproducibility of ultrasonographic (US) findings of rectosigmoid endometriosis among examiners with different level of expertise using stored three-dimensional (3D) volumes of the posterior compartment of the pelvis as a part of SANABA (Sardinia-Navarra-Barcelona) collaborative study. Materials and methods: Six examiners in 3 academic Department of Obstetrics and Gynecology, with different levels of experience and blinded to each other, evaluated 60 stored 3D volumes from the posterior compartment of the pelvis and looked for the presence or absence of features of rectosigmoid endometriotic lesions defined as an irregular hypoechoic nodule with or without hypoechoic foci at the level of the muscularis propria of the anterior wall rectum sigma. Multiplanar view and virtual navigation were used. All examiners had to assess the 3D volume of posterior compartment of the pelvis and classify it as present or absent disease. To analyze intra-observer and the inter-observer agreements, each examiner performed the assessment twice with a 2-week interval between the first and second assessments. Reproducibility was assessed by calculating the weighted Kappa index. Results: Intra-observer reproducibility was moderate to very good for all observers (Kappa index ranging from 0.49 to 0.96) associated with a good diagnostic accuracy of each reader. Inter-observer reproducibility was fair to very good (Kappa index range: 0.21–0.87). Conclusions: The typical US sign of rectosigmoid endometriosis is reasonably recognizable to observers with different level of expertise when assessed in stored 3D volumes

Ultrasonography and atypical sites of endometriosis

In the present pictorial we show the ultrasonographic appearances of endometriosis in atypical sites. Scar endometriosis may present as a hypoechoic solid nodule with hyperechoic spots while umbilical endometriosis may appear as solid or partially cystic areas with ill-defined margins. In the case of endometriosis of the rectus muscle, ultrasonography usually demonstrates a heterogeneous hypoechogenic formation with indistinct edges. Inguinal endometriosis is quite variable in its ultrasonographic presentation showing a completely solid mass or a mixed solid and cystic mass. The typical ultrasonographic finding associated with perineal endometriosis is the presence of a solid lesion near to the episiotomy scar. Under ultrasonography, appendiceal endometriosis is characterized by a solid lesion in the wall of the small bowel, usually well defined. Superficial hepatic endometriosis is characterized by a small hypoechoic lesion interrupting the hepatic capsula, usually hyperechoic. Ultrasound endometriosis of the pancreas is characterized by a small hypoechoic lesion while endometriosis of the kidney is characterized by a hyperechoic small nodule. Diaphragmatic endometriosis showed typically small hypoechoic lesions. Only peripheral nerves can be investigated using ultrasound, with a typical solid appearance. In conclusion, ultrasonography seems to have a fundamental role in the majority of endometriosis cases in "atypical" sites, in all the cases where "typical" clinical findings are present

A Rac/Cdc42 exchange factor complex promotes formation of lateral filopodia and blood vessel lumen morphogenesis

During angiogenesis, Rho GTPases influence endothelial cell migration and cell-cell adhesion; however it is not known whether they control formation of vessel lumens, which are essential for blood flow. Here, using an organotypic system that recapitulates distinct stages of VEGF-dependent angiogenesis, we show that lumen formation requires early cytoskeletal remodelling and lateral cell-cell contacts, mediated through the RAC1 guanine nucleotide exchange factor (GEF) DOCK4. DOCK4 signalling is necessary for lateral filopodial protrusions and tubule remodelling prior to lumen formation, whereas proximal, tip filopodia persist in the absence of DOCK4. VEGF-dependent Rac activation via DOCK4 is necessary for CDC42 activation to signal filopodia formation and depends on the activation of RHOG through the RHOG GEF, SGEF. VEGF promotes interaction of DOCK4 with the CDC42 GEF DOCK9. These studies identify a novel Rho-family GTPase activation cascade for the formation of endothelial cell filopodial protrusions necessary for tubule remodelling, thereby influencing subsequent stages of lumen morphogenesis

AXL inhibition prevents NAFLD progression in mice with soluble AXL as marker of the NAFLD to NASH transition

Trabajo presentado en el The Digital International Liver Congress, celebrado del 27 al 29 de agosto de 2020Background and Aims: TYRO3, AXL and MERTK are receptor tyrosine kinases activated by the ligand GAS6. AXL signalling is increased in NASH patients, promotes fibrosis in hepatic stellate cells and inflammation in Kupffer cells, while GAS6 protects hepatocytes against lipotoxicity via MERTK. Recent data has shown that the AXL kinase inhibitor bemcentinib, by blocking AXL signalling and increasing GAS6 levels, reduces experimental NASH. However, AXL's role in the NAFLD/NASH transition has not been addressed. Identifying mechanisms responsible for NAFLD progression into NASH could provide early markers and novel therapeutic targets. Method: Mice were fed a high-fat methionine-restricted choline deficient (HFCD) diet for 2 and 4 weeks, and a high-fat diet with fructose (HFF) for 4 months to induce different degrees of NAFLD/NASH. Mouse Gas6, soluble levels of Axl (sAXL) and Mertk were measured by ELISA. Human GAS6, sAXL and MERTK were measured by ELISA in control and patient serum, and compared with biochemical and histological data. Transaminases and triglycerides were measured at the Hospital Clinic Core. The collagen content was measured by staining with Sirius Red and quantified by imaging software. H&E staining was performed and NAS score evaluated. Transcriptomic analysis of genes related to liver inflammation and fibrosis were measured in commercial microarrays and by qPCR. Results: After 4 weeks feeding with HFCD diet, early NASH was detected featuring liver steatosis, liver inflammation, hepatocellular ballooning and fibrosis. AXL inhibition with bemcentinib for 2 weeks reduced all these hepatic anomalies, including triglyceride serums levels and liver steatosis, preventing NAFLD progression. After 2 weeks of HFCD diet, mice presented fatty liver without fibrosis; however, transcriptomic analysis evidenced strong upregulation of pro-fibrotic and pro-inflammatory genes, while soluble Axl levels were already increased. Of note, one week bemcentinib administration not only reduced specific inflammatory and fibrotic genes such as Ccr2 or Col1a1, but also hepatic steatosis and NAS score. In contrast,in HFF-fed mice only liver steatosis was observed, without evidence of fibrosis or inflammation nor changes in sAxl levels. Interestingly, previous and on-going clinical data show significant sAXL increase in clinical patients with only diagnosed liver steatosis, showing no histological signs of inflammation or fibrosis. These results justify further transcriptomic patient evaluation and possible evolution depending on sAXL levels. Conclusion: sAXL levels reveals as a potential NAFLD-NASH transition marker, indicative of the initiation of liver inflammation and fibrosis before histological detection. Early treatment with bemcentinib prevented experimental NASH appearance, pointing to AXL antagonism as possible strategy for future clinical trials