Journal of Experimental & Clinical Cancer Research最新文献

Background: Pancreatic ductal adenocarcinoma (PDAC) is known to develop through a stepwise progression from precursor lesions, such as pancreatic intraepithelial neoplasias (PanIN). An alternative carcinogenic pathway has been proposed via transformation of acinar cells, with development of acinar-ductal metaplasia (ADM) and atypical flat lesions (AFL). Defining the characteristics of PDAC precursors is crucial to better understand PDAC carcinogenesis.

Methods: 15 KC (Ptf1a^Cre/+, Kras^LSLG12D/+) and 15 KPC-like mice (Ptf1a^Cre/+, Kras^LSLG12D/+, Trp53^LoxP/LoxP, referred as fKPC hereafter) were sacrificed at different time points. A meticulous morphological evaluation was performed to define different lesion types. Multiplex immunofluorescence staining was applied to define the characteristics of the immune and stromal microenvironment of the lesions. To investigate the association between the genetic alterations and the components of the microenvironment, all lesion types were subjected to next-generation sequencing (NGS) using a 20 genes-panel.

Results: AFL showed a trend towards a more intense immune cell infiltration compared to PanIN and ADM. AFL had higher number of CD4⁺ helper T cells, FOXP3⁺ regulatory T cells, and CD19⁺ B cells than all other analyzed lesions. They displayed more CD8⁺ cytotoxic T cells and FOXP3⁺ cells than PDAC, while peripheral and central PDAC tissues tended to be infiltrated by macrophages in higher frequency. In addition, αSMA-expressing myofibroblastic cancer-associated fibroblasts were tendentially more frequent in AFL than other lesions. PDAC appeared to have higher CXCL12 expression and more common CD109⁺ cells than other lesions. In NGS analysis, none of the lesions in fKPC mice revealed additional coding mutations, while the preneoplastic lesions in 7 KC mice showed variable coding alterations in 16 different genes. The most frequently affected genes were Arid1a, Rnf43, and Pik3ca. PDAC precursors in KC mice showed more dense infiltration of adaptive immune cells than in fKPC mice, supporting the immunosuppressive role of Trp53 alterations.

Conclusions: Our study highlights the unique immunological and stromal features of AFL. Moreover, reinforcing their potential as precursor lesions, ADM and AFL exhibit variable alterations in the genes that have a critical role in PDAC carcinogenesis.

Background: Bcl-xL plays an important role in tumors from different origins, including melanoma, and for this reason it has been widely targeted with small-molecule BH3 mimetics, which unfortunately show several adverse effects. To overcome this limitation, selective Bcl-xL proteolysis-targeting chimera degraders have been developed. Among these, DT2216, a candidate in phase I/II clinical trials, has demonstrated antitumoral activity in preclinical cancer models from different origins, not including melanoma.

Methods: By using several established and patient-derived BRAF wild type and mutated melanoma cells, we performed western blot analysis and MTT assay to study DT2216 effect on Bcl-xL protein levels and cell viability, respectively. Combination studies were performed on BRAF mutated melanoma cells treated with DT2216 and Dabrafenib/Trametinib or on wild type melanoma cells treated with DT2216 and Trametinib or S63845. Combination index was calculated to study drug interactions. Apoptotic induction was studied through western blot (PARP-1 cleavage), cytofluorimetric (subG1 peak in the cell cycle) and live-cell fluorescent imaging of activated caspases 3/7 analyses. Group differences were analysed with a two-sided paired or unpaired Student's t-test. To investigate the effect of the combination treatment in vivo, A375luc melanoma cells were inoculated in xenograft mice, then treated with Dabrafenib/Trametinib or DT2216, alone or in combination, for three weeks. Differences between groups, were analysed with Mann-Whitney test.

Results: DT2216 induced the specific and long-lasting degradation of Bcl-xL protein, and reduced cell viability, in a concentration-dependent manner. Of note, a positive correlation between Bcl-xL degradation and sensitivity to DT2216 was observed, being cells with higher degradation the most sensitive to DT2216. In combination studies, DT2216 was able to enhance the activity of target therapy regardless BRAF mutational status. Moreover, the Mcl-1 specific inhibitor, S63845, potentiated the efficacy of DT2216 in melanoma cells in which DT2216 determined an increase of Mcl-1 protein. Interestingly, DT2216 also increased the activity of target therapy in melanoma cells resistant to Dabrafenib and Trametinib. Finally, experiments in a xenograft mouse melanoma model highlighted DT2216 potentiating effect of target therapy, not only inducing a significant reduction of tumor growth, but also showing a longer disease control.

Conclusion: Our findings provide new insights for combination therapy including Bcl-xL degradation for melanoma treatment.

Background: N-acetyltransferase 10 (NAT10) mediated N4-acetylcytidine (ac4C) modification has been implicated in tumor progression; however, the precise role and underlying mechanism of NAT10 in breast cancer progression remain largely undefined.

Methods: The expression and prognostic significance of NAT10 in breast cancer were evaluated using clinical tissue samples and public databases. Functional assays were performed in vitro and in vivo to assess the effects of NAT10 on tumor growth and immune evasion. Mechanistic studies, including RNA immunoprecipitation (RIP), ac4C RNA immunoprecipitation (acRIP), and co-immunoprecipitation (Co-IP), were conducted to elucidate the interaction between NAT10 and histone deacetylase 4 (HDAC4) and their roles in regulating NF-κB signaling and programmed death-ligand 1 (PD-L1) expression.

Results: NAT10 expression was significantly upregulated in breast cancer and correlated with poor patient prognosis. NAT10 mediated ac4C modification enhanced the stability of HDAC4 mRNA, thereby promoting HDAC4 expression. Conversely, HDAC4 stabilized NAT10 protein through post-transcriptional deacetylation, forming a self-reinforcing regulatory loop. Elevated HDAC4 activated the NF-κB signaling pathway, resulting in increased PD-L1 transcription and enhanced immune evasion of breast cancer cells. Inhibition of the NAT10/HDAC4/NF-κB axis markedly reduced PD-L1 expression and restored antitumor immune responses.

Conclusion: Our findings identify a self-reinforcing NAT10/HDAC4 signaling circuit that drives breast cancer progression and immune evasion. Targeting NAT10 represents a promising therapeutic strategy to overcome immunosuppression and improve patient outcomes in breast cancer.