The pRb/RBL2-E2F1/4-GCN5 axis regulates cancer stem cell formation and G0 phase entry/exit by paracrine mechanisms.

The lethality, chemoresistance and metastatic characteristics of cancers are associated with phenotypically plastic cancer stem cells (CSCs). How the non-cell autonomous signalling pathways and cell-autonomous transcriptional machinery orchestrate the stem cell-like characteristics of CSCs is still poorly understood. Here we use a quantitative proteomic approach for identifying secreted proteins of CSCs in pancreatic cancer. We uncover that the cell-autonomous E2F1/4-pRb/RBL2 axis balances non-cell-autonomous signalling in healthy ductal cells but becomes deregulated upon KRAS mutation. E2F1 and E2F4 induce whereas pRb/RBL2 reduce WNT ligand expression (e.g. WNT7A, WNT7B, WNT10A, WNT4) thereby regulating self-renewal, chemoresistance and invasiveness of CSCs in both PDAC and breast cancer, and fibroblast proliferation. Screening for epigenetic enzymes identifies GCN5 as a regulator of CSCs that deposits H3K9ac onto WNT promoters and enhancers. Collectively, paracrine signalling pathways are controlled by the E2F-GCN5-RB axis in diverse cancers and this could be a therapeutic target for eliminating CSCs.

KMT2A associates with PHF5A-PHF14-HMG20A-RAI1 subcomplex in pancreatic cancer stem cells and epigenetically regulates their characteristics.

Pancreatic cancer (PC), one of the most aggressive and life-threatening human malignancies, is known for its resistance to cytotoxic therapies. This is increasingly ascribed to the subpopulation of undifferentiated cells, known as pancreatic cancer stem cells (PCSCs), which display greater evolutionary fitness than other tumor cells to evade the cytotoxic effects of chemotherapy. PCSCs are crucial for tumor relapse as they possess 'stem cell-like' features that are characterized by self-renewal and differentiation. However, the molecular mechanisms that maintain the unique characteristics of PCSCs are poorly understood. Here, we identify the histone methyltransferase KMT2A as a physical binding partner of an RNA polymerase-associated PHF5A-PHF14-HMG20A-RAI1 protein subcomplex and an epigenetic regulator of PCSC properties and functions. Targeting the protein subcomplex in PCSCs with a KMT2A-WDR5 inhibitor attenuates their self-renewal capacity, cell viability, and in vivo tumorigenicity.

Ciliated Hepatic Foregut Cysts: Not as Rare as Previously Believed.

Background. Ciliated hepatic foregut cysts (CHFCs) are uncommon cystic lesions within the liver. CHFCs can undergo a malignant transformation to form a primary squamous cell carcinoma of the liver. The true incidence and natural history of CHFCs is unknown and the risk of malignant transformation is unclear. We present a single centre's experience of CFHC management. Methods. A retrospective review of a departmental database identified all patients with CHFCs over a 4 year time period. Patients with CHFCs confirmed on histological assessment or suspected on radiological imaging were included in this study. Clinical information regarding patient demographics, symptomatic presentation, surgical management and histopathological features were noted. The radiological characteristics of CHFCs were recorded and the malignant transformation rate was calculated. Results. 15 patients with CHFC were identified (7 histologically confirmed and 8 radiologically suspected cases). All patients were asymptomatic and the CHFCs were incidental findings. No CHFC developed an interval change in cyst features or underwent a malignant transformation during follow up. MRI serves as the most sensitive modality to diagnose CHFC. Conclusions. CHFCs may be more prevalent than previously reported. Definitive management should encompass a patient centred discussion regarding the merits of long term follow up with serial imaging versus resection on an individual basis once CHFC is diagnosed.

Activated Regulatory T-Cells, Dysfunctional and Senescent T-Cells Hinder the Immunity in Pancreatic Cancer.

Pancreatic cancer has one of the worst prognoses of any human malignancy and leukocyte infiltration is a major prognostic marker of the disease. As current immunotherapies confer negligible survival benefits, there is a need to better characterise leukocytes in pancreatic cancer to identify better therapeutic strategies. In this study, we analysed 32 human pancreatic cancer patients from two independent cohorts. A multi-parameter mass-cytometry analysis was performed on 32,000 T-cells from eight patients. Single-cell RNA sequencing dataset analysis was performed on a cohort of 24 patients. Multiplex immunohistochemistry imaging and spatial analysis were performed to map immune infiltration into the tumour microenvironment. Regulatory T-cell populations demonstrated highly immunosuppressive states with high TIGIT, ICOS and CD39 expression. CD8+ T-cells were found to be either in senescence or an exhausted state. The exhausted CD8 T-cells had low PD-1 expression but high TIGIT and CD39 expression. These findings were corroborated in an independent pancreatic cancer single-cell RNA dataset. These data suggest that T-cells are major players in the suppressive microenvironment of pancreatic cancer. Our work identifies multiple novel therapeutic targets that should form the basis for rational design of a new generation of clinical trials in pancreatic ductal adenocarcinoma.

Pleomorphic rhabdomyosarcoma of the uterus in a postmenopausal patient.

Pure rhabdomyosarcomas occurring in the adult uterus are very rare, with poor prognosis. We present a case of a 67-year-old woman with postmenopausal vaginal bleeding caused by pleomorphic rhabdomyosarcoma of the uterus, treated with hysterectomy, bilateral salpingo-oophorectomy, pelvic/paraaortic lymphadenectomy and partial sigmoidectomy. Postoperative chemotherapy (Doxorubicin) was given according to protocol. Follow-up examinations one year after surgery revealed no abnormalities or tumor recurrence. The rarity of this histological entity makes the presented case worthy of publication.