PTEN deficiency induces an extrahepatic cholangitis-cholangiocarcinoma continuum via aurora kinase A in mice.

BACKGROUND & AIMS: The PTEN-AKT pathway is frequently altered in extrahepatic cholangiocarcinoma (eCCA). We aimed to evaluate the role of PTEN in the pathogenesis of eCCA and identify novel therapeutic targets for this disease. METHODS: The Pten gene was genetically deleted using the Cre-loxp system in biliary epithelial cells. The pathologies were evaluated both macroscopically and histologically. The characteristics were further analyzed by immunohistochemistry, reverse-transcription PCR, cell culture, and RNA sequencing. Some features were compared to those in human eCCA samples. Further mechanistic studies utilized the conditional knockout of Trp53 and Aurora kinase A (Aurka) genes. We also tested the effectiveness of an Aurka inhibitor. RESULTS: We observed that genetic deletion of the Pten gene in the extrahepatic biliary epithelium and peri-ductal glands initiated sclerosing cholangitis-like lesions in mice, resulting in enlarged and distorted extrahepatic bile ducts in mice as early as 1 month after birth. Histologically, these lesions exhibited increased epithelial proliferation, inflammatory cell infiltration, and fibrosis. With aging, the lesions progressed from low-grade dysplasia to invasive carcinoma. Trp53 inactivation further accelerated disease progression, potentially by downregulating senescence. Further mechanistic studies showed that both human and mouse eCCA showed high expression of AURKA. Notably, the genetic deletion of Aurka completely eliminated Pten deficiency-induced extrahepatic bile duct lesions. Furthermore, pharmacological inhibition of Aurka alleviated disease progression. CONCLUSIONS: Pten deficiency in extrahepatic cholangiocytes and peribiliary glands led to a cholangitis-to-cholangiocarcinoma continuum that was dependent on Aurka. These findings offer new insights into preventive and therapeutic interventions for extrahepatic CCA. IMPACT AND IMPLICATIONS: The aberrant PTEN-PI3K-AKT signaling pathway is commonly observed in human extrahepatic cholangiocarcinoma (eCCA), a disease with a poor prognosis. In our study, we developed a mouse model mimicking cholangitis to eCCA progression by conditionally deleting the Pten gene via Pdx1-Cre in epithelial cells and peribiliary glands of the extrahepatic biliary duct. The conditional Pten deletion in these cells led to cholangitis, which gradually advanced to dysplasia, ultimately resulting in eCCA. The loss of Pten heightened Akt signaling, cell proliferation, inflammation, fibrosis, DNA damage, epigenetic signaling, epithelial-mesenchymal transition, cell dysplasia, and cellular senescence. Genetic deletion or pharmacological inhibition of Aurka successfully halted disease progression. This model will be valuable for testing novel therapies and unraveling the mechanisms of eCCA tumorigenesis.

Albumin promoter-driven FlpO expression induces efficient genetic recombination in mouse liver.

Tissue-specific gene manipulations are widely used in genetically engineered mouse models. A single recombinase system, such as the one using Alb-Cre, has been commonly used for liver-specific genetic manipulations. However, most diseases are complex, involving multiple genetic changes and various cell types. A dual recombinase system is required for conditionally modifying different genes sequentially in the same cell or inducing genetic changes in different cell types within the same organism. A FlpO cDNA was inserted between the last exon and 3'-UTR of the mouse albumin gene in a bacterial artificial chromosome (BAC-Alb-FlpO). The founders were crossed with various reporter mice to examine the efficiency of recombination. Liver cancer tumorigenesis was investigated by crossing the FlpO mice with FSF-KrasG12D mice and p53frt mice (KPF mice). BAC-Alb-FlpO mice exhibited highly efficient recombination capability in both hepatocytes and intrahepatic cholangiocytes. No recombination was observed in the duodenum and pancreatic cells. BAC-Alb-FlpO-mediated liver-specific expression of mutant KrasG12D and conditional deletion of p53 gene caused the development of liver cancer. Remarkably, liver cancer in these KPF mice manifested a distinctive mixed hepatocellular carcinoma and cholangiocarcinoma phenotype. A highly efficient and liver-specific BAC-Alb-FlpO mouse model was developed. In combination with other Cre lines, different genes can be manipulated sequentially in the same cell, or distinct genetic changes can be induced in different cell types of the same organism.NEW & NOTEWORTHY A liver-specific Alb-FlpO mouse line was generated. By coupling it with other existing CreERT or Cre lines, the dual recombinase approach can enable sequential gene modifications within the same cell or across various cell types in an organism for liver research through temporal and spatial gene manipulations.

A simple and effective genotyping workflow for rapid detection of CRISPR genome editing.

Genetically engineered mouse models play a pivotal role in the modeling of diseases, exploration of gene functions, and the development of novel therapies. In recent years, clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9)-mediated genome editing technology has revolutionized the process of developing such models by enabling precise genome modifications of the multiple interested genes simultaneously. Following genome editing, an efficient genotyping methodology is crucial for subsequent characterization. However, current genotyping methods are laborious, time-consuming, and costly. Here, using targeting the mouse trypsinogen genes as an example, we introduced common applications of CRISPR-Cas9 editing and a streamlined cost-effective genotyping workflow for CRISPR-edited mouse models, in which Sanger sequencing is required only at the initial steps. In the F0 mice, we focused on identifying the presence of positive editing by PCR followed by Sanger sequencing without the need to know the exact sequences, simplifying the initial screening. In the F1 mice, Sanger sequencing and algorithms decoding were used to identify the precise editing. Once the edited sequence was established, a simple and effective genotyping strategy was established to distinguish homozygous and heterozygous status by PCR from tail DNA. The genotyping workflow applies to deletions as small as one nucleotide, multiple-gene knockout, and knockin studies. This simplified, efficient, and cost-effective genotyping shall be instructive to new investigators who are unfamiliar with characterizing CRISPR-Cas9-edited mouse strains.NEW & NOTEWORTHY This study presents a streamlined, cost-effective genotyping workflow for clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) edited mouse models, focusing on trypsinogen genes. It simplifies initial F0 mouse screening using PCR and Sanger sequencing without needing exact sequences. For F1 mice, precise editing is identified through Sanger sequencing and algorithm decoding. The workflow includes a novel PCR strategy for distinguishing homozygous and heterozygous statuses in subsequent generations, effective for small deletions, multiple-gene knockouts, and knockins.

A mouse model for high-efficient Flp-recombinase-mediated genetic manipulation in the pancreas.

BACKGROUND: Tissue and cell-specific gene targeting has been widely employed in biomedical research. In the pancreas, the commonly used Cre recombinase recognizes and recombines loxP sites. However, to selectively target different genes in distinct cells, a dual recombinase system is required. METHOD: We developed an alternative recombination system mediated by FLPo, which recognizes frt DNA sequences for pancreatic dual recombinase-mediated genetic manipulation. An IRES-FLPo cassette was targeted between the translation stop code and 3-UTR of the mouse pdx1 gene in a Bacterial Artificial Chromosome using recombineering technology. Transgenic BAC-Pdx1-FLPo mice were developed by pronuclear injection. RESULTS: Highly efficient recombination activity was observed in the pancreas by crossing the founder mice with Flp reporter mice. When the BAC-Pdx1-FLPo mice were bred with conditional FSF-KRasG12D and p53 F/F mice, pancreatic cancer developed in the compound mice. The characteristics of pancreatic cancer resembled those derived from conditional LSL-KRasG12D and p53 L/L mice controlled by pdx1-Cre. CONCLUSIONS: We have generated a new transgenic mouse line expressing FLPo, which enables highly efficient pancreatic-specific gene recombination. When combined with other available Cre lines, this system can be utilized to target different genes in distinct cells for pancreatic research.

Impact of endogenous glucocorticoid on response to immune checkpoint blockade in patients with advanced cancer.

Background: Previous studies indicate that exogenous use of glucocorticoid (GC) affects immune checkpoint inhibitor (ICI) efficacy. However, there is a paucity of clinical data evaluating the direct impact of endogenous GC on the efficacy for cancer patients with immune checkpoint blockade. Methods: We first compared the endogenous circulating GC levels in healthy individuals and patients with cancer. We next retrospectively reviewed patients with advanced cancer with PD-1/PD-L1 inhibitor alone or combination therapy in a single center. The effects of baseline circulating GC levels on objective response rate (ORR), durable clinical benefit (DCB), progression-free survival (PFS), and overall survival (OS) were analyzed. The association of the endogenous GC levels with circulating lymphocytes, cytokines levels, and neutrophil to lymphocyte ratio, and tumor infiltrating immune cells, were systematically analyzed. Results: The endogenous GC levels in advanced cancer patients were higher than those in early-stage cancer patients as well as healthy people. In the advanced cancer cohort with immune checkpoint blockade (n=130), patients with high baseline endogenous GC levels (n=80) had a significantly reduced ORR (10.0% vs 40.0%; p<0.0001) and DCB (35.0% vs 73.5%, p=0.001) compared to those with low endogenous GC levels (n=50). The increased GC levels was significantly associated with reduced PFS (HR 2.023; p=0.0008) and OS (HR 2.809; p=0.0005). Moreover, statistically significant differences regarding PFS, and OS were also detected after propensity score matching. In a multivariable model, the endogenous GC was identified as an independent indicator for predicting PFS (HR 1.779; p=0.012) and OS (HR 2.468; p=0.013). High endogenous GC levels were significantly associated with reduced lymphocytes (p=0.019), increased neutrophil to lymphocyte ratio (p=0.0009), and increased interleukin-6 levels (p=0.025). Patients with high levels of endogenous GC had low numbers of tumor infiltrating CD3+ (p=0.001), CD8+ T (p=0.059), and CD4+ T (p=0.002) cells, and the numbers of circulating PD-1+ NK cells (p=0.012), and the ratio of CD8+PD-1+ to CD4+PD-1+ (p=0.031) were higher in patients with high levels of endogenous GC compared to low levels of endogenous GC. Conclusion: Baseline endogenous GC increase executes a comprehensive negative effect on immunosurveillance and response to immunotherapy in real-world cancer patients accompanied with cancer progression.

Immune-related dissociated response as a specific atypical response pattern in solid tumors with immune checkpoint blockade.

Immune checkpoint blockade using immune checkpoint inhibitors, including cytotoxic T-lymphocyte-associated antigen-4 and programmed cell death protein-1/programmed cell death ligand-1 inhibitors, has revolutionized systematic treatment for advanced solid tumors, with unprecedented survival benefit and tolerable toxicity. Nivolumab, pembrolizumab, cemiplimab, avelumab, durvalumab, atezolizumab, and ipilimumab are currently approved standard treatment options for various human cancer types. The response rate to immune checkpoint inhibitors, however, is unsatisfactory, and unexpectedly, atypical radiological responses, including delayed responses, pseudoprogression, hyperprogression, and dissociated responses (DRs), are observed in a small subgroup of patients. The benefit of immunotherapy for advanced patients who exhibit atypical responses is underestimated according to the conventional response evaluation criteria in solid tumors (RECIST). In particular, DR is considered a mixed radiological or heterogeneous response pattern when responding and nonresponding lesions or new lesions coexist simultaneously. The rate of DR reported in different studies encompass a wide range of 3.3-47.8% based on diverse definition of DR. Although DR is also associated with treatment efficacy and a favorable prognosis, it is different from pseudoprogression, which has concordant progressive lesions and can be regularly captured by immune RECIST. This review article aims to comprehensively determine the frequency, definition, radiological evaluation, probable molecular mechanisms, prognosis, and clinical management of immune-related DR and help clinicians and radiologists objectively and correctly interpret this specific atypical response and better understand and manage cancer patients with immunotherapy and guarantee their best clinical benefit.

Dynamics of Early Serum Tumour Markers and Neutrophil-to-Lymphocyte Ratio Predict Response to PD-1/PD-L1 Inhibitors in Advanced Non-Small-Cell Lung Cancer.

PURPOSE: To evaluate the dynamics of early serum tumour markers (STMs) and the neutrophil-to-lymphocyte ratio (NLR) to predict clinical efficacy and prognosis of advanced non-small-cell lung cancer (NSCLC) patients who received programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) inhibitors. PATIENTS AND METHODS: We retrospectively reviewed patients with advanced NSCLC treated with PD-1/PD-L1 inhibitors between September 2017 and August 2020. NLR and STMs were routinely measured between immunotherapy initiation and the first radiological evaluation. A combination score based on the leading STM and NLR and their dynamic changes was established. The effects of leading STM change, NLR change, and the combination score on the objective response rate (ORR), durable clinical benefit (DCB), progression-free survival (PFS), and overall survival (OS) were analysed. The accuracy of the combination score was evaluated by receiver operating characteristic (ROC) curve and the area under the curve (AUC). RESULTS: Overall, 124 patients were included in this retrospective cohort study. The ORR was 22.8%, DCB was 54.5%, and the median OS and PFS were 21.6 and 14.9 months, respectively. Patients with low combination scores had a significantly improved ORR and DCB compared with those with intermediate or high scores (P = 0.002 for ORR, P < 0.0001 for DCB). In a multivariate model, the combination score was an independent indicator of PFS (P < 0.0001) and OS (P < 0.0001). The AUC demonstrated that the combination score (AUC = 0.706) has greater predictive power than either the posttreatment NLR (AUC = 0.668) or the leading STM change (AUC = 0.648) alone. CONCLUSION: An easy, cost-effective, and novel combination score based on the dynamics of an early STM and the NLR can accurately predict the clinical efficacy of PD-1/PD-L1 inhibitors and prognosis in advanced NSCLC patients.

Excellent Response to Atezolizumab After Clinically Defined Hyperprogression Upon Previous Treatment With Pembrolizumab in Metastatic Triple-Negative Breast Cancer: A Case Report and Review of the Literature.

Immunotherapy with immune checkpoint inhibitors (ICIs), including programmed cell death protein-1 (PD-1) and programmed cell death ligand-1 (PD-L1) inhibitors, has revolutionized the systematic treatment of advanced and metastatic solid tumors. However, the response rate to ICIs is unsatisfactory, and unexpected hyperprogressive disease (HPD) is even observed in a small subgroup of patients. Patients with HPD usually have worsening clinical symptoms and poorer survival, and therapeutic strategies are extremely limited. Here, we presented a patient with HPD who had used a PD-L1 inhibitor and was highly responsive to the sequential use of a PD-1 inhibitor. A 67-year-old woman with metastatic triple-negative breast cancer was treated with pembrolizumab plus chemotherapy after progression on previous multiple-line chemotherapy treatments. After 2 cycles of treatments, she rapidly developed HPD, as confirmed by radiological evaluation and worsening symptoms. At that time, pembrolizumab was discontinued, and she switched to the PD-L1 inhibitor atezolizumab plus chemotherapy. This patient partially responded to atezolizumab plus chemotherapy without experiencing severe drug-related adverse effects. This is the first reported case of metastatic breast cancer in a patient with radiologically confirmed HPD after pembrolizumab therapy in which successful rechallenge with atezolizumab relieved clinical symptoms. Further studies with larger sample sizes involving a deeper translational investigation of HPD are needed to confirm the efficacy and mechanism of sequential application of different ICIs for the clinical management of HPD.

Stathmin is a potential molecular marker and target for the treatment of gastric cancer.

OBJECTIVE: This study is to investigate the expression levels of stathmin in tissues of gastric cancer, and evaluate the therapeutic effects of stathmin antisense oligodeoxynucleotide (ASODN) and/or docetaxel in human gastric cancer cells. METHODS: Immunohistochemistry was performed to detect the expression levels of stathmin in gastric cancer and adjacent tissues. Stathmin ASODN was transfected into gastric cancer SGC 7901 cell lines. The cell proliferation was assessed with the MTT assay, and the inhibitory rates were calculated. RT-PCR and Western blot analysis were performed to detect the mRNA and protein expression levels of stathmin, respectively. The synergistic effects of stathmin ASODN and docetaxel were evaluated. The efficacy and clinical benefit rates of the treatment of docetaxel combined with stathmin evaluation were investigated and compared. RESULTS: Our results showed that the expression of stathmin was elevated in gastric cancer tissues, indicating a possible association between the stathmin expression and the disease occurrence. The MTT assay and tumor growth experiment revealed that stathmin ASODN significantly inhibited the proliferation of gastric cancer cells, both in vitro and in vivo. Furthermore, stathmin ASDON enhanced the inhibitory effects of docetaxel on the proliferation of gastric cancer cells, indicating a synergistic effect for the combination treatment. Importantly, docetaxel treatment was more effective for stathmin-negative gastric cancer patients, compared with stathmin-positive patients. CONCLUSION: Stathmin expression provides evidence for the treatment planning for gastric cancers. Stathmin might be a potential molecular marker and target for the treatment of gastric cancer.