Anti-proliferative effect of atrial natriuretic peptide on colorectal cancer cells: evidence for an Akt-mediated cross-talk between NHE-1 activity and Wnt/β-catenin signaling

Acidic tumor microenvironment and Wnt/β-catenin pathway activation have been recognized as two crucial events associated with the initiation and progression of cancer. The aim of this study was to clarify the molecular mechanisms underlying the anti-proliferative effects of atrial natriuretic peptide (ANP) as well as to investigate the relationship between the cellular pH and the Wnt/β-catenin signaling in cancer cells.To pursue our aims, we conducted investigations in DHD/K12/Trb rat colon adenocarcinoma cells. Intracellular pH was measured by Confocal Laser Scanning Microscopy (CLSM) using the lysosensor Green DND-189 probe. Expression of crucial molecules in the Wnt/β-catenin signaling pathway was analyzed by CLSM, western blot, and real time PCR. Measurements of activation (phosphorylation state) of Akt, ERK1/2, and p38MAPKinase were performed by Reverse-Phase Protein Microarray Analysis (RPMA).We showed that ANP triggered a NHE-1-mediated increase of the intracellular acidity, inhibiting the Wnt/β-catenin signaling simultaneously. Moreover, we observed that the Wnt1a, a Wnt signaling activator, affected the intracellular pH in an opposite fashion. Results from the comparative analysis of ANP and EIPA (a NHE-1 specific inhibitor) showed that these two molecules affect both the intracellular acidification and the Wnt/β-catenin signaling cascade. Specifically, ANP acts on the upstream of the cascade, through a Frizzled-mediated activation, while EIPA does on the downstream.We show for the first time that the Akt activity might be a relevant molecular event linking the NHE-1-regulated intracellular pH and the Wnt/β-catenin signaling. This provides evidence for a cross-talk between the intracellular alkalinization and the Wnt signaling in tumor cells.

The HIV-Tat protein induces chromosome number aberrations by affecting mitosis

To analyze the effects of the HIV-Tat-tubulin interaction, we microinjected HIV-Tat purified protein into Drosophila syncytial embryos. Following the Tat injection, altered timing of the cortical nuclear cycles was observed; specifically, the period between the nuclear envelope breakdown and anaphase initiation was lengthened as was the period between anaphase initiation and the formation of the next nuclear envelope. These two periods correspond to kinetochore alignment at metaphase and to mitosis exit, respectively. We also demonstrated that these two delays are the consequence of damage specifically induced by Tat on kinetochore alignment and on the timing of sister chromatid segregation at anaphase. Furthermore, we show that the expression of Tat in Drosophila larvae brain cells produces a significant percentage of polyploid and aneuploid cells. The results reported here indicate that Tat impairs the mitotic process and that Tat-tubulin interaction appears to be responsible for the observed defects. The presence of polyploid and aneuploid cells is consistent with a delay or arrest in the M phase of a substantial fraction of the cells expressing Tat, suggesting that mitotic spindle checkpoints are overridden following Tat expression.

A small sequence in domain v of the mitochondrial large ribosomal RNA restores Drosophila melanogaster pole cell determination in uv-irradiated embryos

The mechanism by which the mitochondrial large rRNA is involved in the restoration of the pole cell-forming ability in Drosophila embryos is still unknown. We identified a 15-ribonucleotide sequence which is conserved from the protobacterium Wolbachia to the higher eukaryotes in domain V of the mitochondrial large rRNA. This short sequence is sufficient to restore pole cell determination in UV-irradiated Drosophila embryos. Here, we provide evidence that the conserved 15-base sequence is sufficient to restore luciferase activity in vitro. Moreover, we show that the internal GAGA sequence is involved in protein binding and that mutations in this tetranucleotide affect the sequence's ability to restore luciferase activity. The obtained results lead us to propose that mtlrRNA may be involved either in damaged protein reactivation or in protein biosynthesis during pole cell determination.

328 Patellar Height After Anterior Cruciate Ligament Rupture Reconstruction Using the Autologous Bone-Patellar Tendon-Bone Graft Technique in The Maltese Population

Aim

The primary aim of this study is to determine whether there is a change in patellar height after closure of the patellar tendon defect after a bone-patellar tendon-bone graft harvesting. The secondary aim is to evaluate clinical and functional outcomes.

Method

A retrospective observational study was conducted. Patients who were diagnosed with ACL injury and underwent reconstruction of ACL using the B-p-T-B graft technique from 2015 to 2020 were included (56 patients). All patients underwent the same procedural steps in the same centre. All patients had pre- and post-operative knee radiographs (antero-posterior and lateral views). The Caton- Deschamps Index was used to measure patellar height pre- and post-operatively. The International Knee Documentation Committee-Subjective Knee Evaluation Form was used to assess functional outcome. Clinical outcome was assessed by reviewing patient records.

Results

There was a change from the pre-op index 0.995 +/- 0.144 (mean +/- SD) to the post-op index 0.948 +/- 0.150. With a statistically significant decrease in index of 0.048 +/- 0.131 (p value 0.009) was found. The null hypothesis (that there is no change) is rejected and therefore the alternative hypothesis (a decrease in patellar height) is accepted. The mean IKDC-SKF score was 76.851 +/- 15.015 (SD) ranging from 40.2 to 100

Conclusions

Performing ACL reconstruction using the B-pT-B technique, although predisposing to a decreased patellar height, it does not increase the incidence of patella baja. An overall good functional outcome was achieved, mean IKDC-SKF 76.85. However, no clear association between change in patellar height and PF symptoms could be demonstrated.