A mouse model for peritoneal metastases of colorectal origin recapitulates patient heterogeneity

CILP2 is a potential biomarker for the prediction and therapeutic target of peritoneal metastases in colorectal cancer

Peritoneal metastases (PM) in colorectal cancer (CRC) is associated with a dismal prognosis. Identifying and exploiting new biomarkers, signatures, and molecular targets for personalised interventions in the treatment of PM in CRC is imperative. We conducted transcriptomic profiling using RNA-seq data generated from the primary tissues of 19 CRC patients with PM. Using our dataset established in a previous study, we identified 1422 differentially expressed genes compared to non-metastatic CRC. The profiling demonstrated no differential expression in liver and lung metastatic CRC. We selected 12 genes based on stringent criteria and evaluated their expression patterns in a validation cohort of 32 PM patients and 84 without PM using real-time reverse transcription-polymerase chain reaction. We selected cartilage intermediate layer protein 2 (CILP2) because of high mRNA expression in PM patients in our validation cohort and its association with a poor prognosis in The Cancer Genome Atlas. Kaplan-Meier survival analysis in our validation cohort demonstrated that CRC patients with high CILP2 expression had significantly poor survival outcomes. Knockdown of CILP2 significantly reduced the proliferation, colony-forming ability, invasiveness, and migratory capacity and downregulated the expression of molecules related to epithelial-mesenchymal transition in HCT116 cells. In an in vivo peritoneal dissemination mouse knockdown of CILP2 also inhibited CRC growth. Therefore, CILP2 is a promising biomarker for the prediction and treatment of PM in CRC.

Thermosensitive methyl-cellulose-based injectable hydrogel carrying oxaliplatin for the treatment of peritoneal metastasis in colorectal cancer

Advanced colorectal cancer (CRC) with peritoneal metastasis (PM) is a highly aggressive malignancy with poor prognosis. Systematic chemotherapy and local treatments are the primary therapeutic approaches. However, systemic chemotherapy is limited by low accumulation of drugs at the tumor site and systemic toxicity. Local treatments include cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). However, CRS faces challenges related to incomplete tumor resection, while HIPEC is restricted by the uneven distribution of drugs and potential complications. Herein, a thermosensitive methyl-cellulose-based injectable hydrogel carrying oxaliplatin (OXA) was synthesized to improve this situation. Specifically, methyl cellulose (MC) coagulated into a hydrogel, and OXA was loaded into the MC hydrogel to construct the OXA-MC hydrogel. We explored the OXA-MC hydrogel for the treatment of PM in CRC. The results demonstrated that the OXA-MC hydrogel had favorable biocompatibility and thermo-sensitivity and could act as a local slow-release drug carrier. Moreover, in a CT-26 tumor-bearing model, it showed a remarkable anti-tumor effect by inhibiting proliferation and promoting apoptosis. Additionally, transcriptome analysis indicated that the OXA-MC hydrogel might be involved in the regulation of the PI3K-AKT signaling pathway. In summary, we successfully prepared the OXA-MC hydrogel and provided a valid approach in the treatment of PM in CRC, which lays a foundation for other PM treatments.

Genomic landscape defines peritoneal metastatic pattern and related target of peritoneal metastasis in colorectal cancer

The primary objective of this study is to develop a prediction model for peritoneal metastasis (PM) in colorectal cancer by integrating the genomic features of primary colorectal cancer, along with clinicopathological features. Concurrently, we aim to identify potential target implicated in the peritoneal dissemination of colorectal cancer through bioinformatics exploration and experimental validation. By analyzing the genomic landscape of primary colorectal cancer and clinicopathological features from 363 metastatic colorectal cancer patients, we identified 22 differently distributed variables, which were used for subsequent LASSO regression to construct a PM prediction model. The integrated model established by LASSO regression, which incorporated two clinicopathological variables and seven genomic variables, precisely discriminated PM cases (AUC 0.899; 95% CI 0.860-0.937) with good calibration (Hosmer-Lemeshow test p = .147). Model validation yielded AUCs of 0.898 (95% CI 0.896-0.899) and 0.704 (95% CI 0.622-0.787) internally and externally, respectively. Additionally, the peritoneal metastasis-related genomic signature (PGS), which was composed of the seven genes in the integrated model, has prognostic stratification capability for colorectal cancer. The divergent genomic landscape drives the driver genes of PM. Bioinformatic analysis concerning these driver genes indicated SERINC1 may be associated with PM. Subsequent experiments indicate that knocking down of SERINC1 functionally suppresses peritoneal dissemination, emphasizing its importance in CRCPM. In summary, the genomic landscape of primary cancer in colorectal cancer defines peritoneal metastatic pattern and reveals the potential target of SERINC1 for PM in colorectal cancer.

Modulating Gut Microbiota Prevents Anastomotic Leak to Reduce Local Implantation and Dissemination of Colorectal Cancer Cells after Surgery

PURPOSE

Anastomotic leak (AL) is a major complication in colorectal cancer surgery and consists of the leakage of intestinal content through a poorly healed colonic wound. Colorectal cancer recurrence after surgery is a major determinant of survival. We hypothesize that AL may allow cancer cells to escape the gut and lead to cancer recurrence and that improving anastomotic healing may prevent local implantation and metastatic dissemination of cancer cells.

EXPERIMENTAL DESIGN

We investigated the association between AL and postoperative outcomes in patients with colorectal cancer. Using mouse models of poor anastomotic healing, we assessed the processes of local implantation and dissemination of cancer cells. The effect of dietary supplementation with inulin and 5-aminosalicylate (5-ASA), which activate PPAR-γ in the gut, on local anastomotic tumors was assessed in mice undergoing colonic surgery. Inulin and 5-ASA were also assessed in a mouse model of liver metastasis.

RESULTS

Patients experiencing AL displayed lower overall and oncologic survival than non-AL patients. Poor anastomotic healing in mice led to larger anastomotic and peritoneal tumors. The microbiota of patients with AL displays a lower capacity to activate the antineoplastic PPAR-γ in the gut. Modulation of gut microbiota using dietary inulin and 5-ASA reinforced the gut barrier and prevented anastomotic tumors and metastatic spread in mice.

CONCLUSIONS

Our findings reinforce the hypothesis that preventing AL is paramount to improving oncologic outcomes after colorectal cancer surgery. Furthermore, they pave the way toward dietary targeting of PPAR-γ as a novel way to enhance healing and diminish cancer recurrence.

The landscape of cell-free mitochondrial DNA in liquid biopsy for cancer detection

BACKGROUND

Existing methods to detect tumor signal in liquid biopsy have focused on the analysis of nuclear cell-free DNA (cfDNA). However, non-nuclear cfDNA and in particular mitochondrial DNA (mtDNA) has been understudied. We hypothesize that an increase in mtDNA in plasma could reflect the presence of cancer, and that leveraging cell-free mtDNA could enhance cancer detection.

RESULTS

We survey 203 healthy and 664 cancer plasma samples from three collection centers covering 12 cancer types with whole genome sequencing to catalogue the plasma mtDNA fraction. The mtDNA fraction is increased in individuals with cholangiocarcinoma, colorectal, liver, pancreatic, or prostate cancer, in comparison to that in healthy individuals. We detect almost no increase of mtDNA fraction in individuals with other cancer types. The mtDNA fraction in plasma correlates with the cfDNA tumor fraction as determined by somatic mutations and/or copy number aberrations. However, the mtDNA fraction is also elevated in a fraction of patients without an apparent increase in tumor-derived cfDNA. A predictive model integrating mtDNA and copy number analysis increases the area under the curve (AUC) from 0.73 when using copy number alterations alone to an AUC of 0.81.

CONCLUSIONS

The mtDNA signal retrieved by whole genome sequencing has the potential to boost the detection of cancer when combined with other tumor-derived signals in liquid biopsies.

Investigation of the effectiveness of hyperthermic intraperitoneal chemotherapy in experimental colorectal peritoneal metastasis model

Objectives

In our study, we aimed to (1) create a peritoneal metastasis (PM) model in nude mice, administer intraperitoneal chemotherapy using the peritoneal infusion pump we developed in this model, and (2) compare the efficacy of intraperitoneal chemotherapy using various drugs at different temperatures.

Methods

The peritoneal metastasis model was established in nude mice using the CC531 colon carcinoma cell line. Models with peritoneal metastasis (PM) were randomized into four groups of seven animals each: Group 1, control group (n=7); Group 2, normothermic intraperitoneal chemotherapy (NIPEC) with mitomycin C(MMC) (n=7); Group 3, hyperthermic intraperitoneal chemotherapy (HIPEC) with mitomycin C (n=7), and Group 4, NIPEC with 5-fluorouracil (5-FU).

Results

Tumor development was achieved in all animals. While the tumor burden decreased significantly in the treatment Group 3 (p=0.034), no significant difference was found in the other groups. In the PM mouse model, hyperthermic intraperitoneal administration of MMC had the highest tumoricidal effect.

Conclusions

Our PM model provided a good opportunity to examine the efficacy of HIPEC and intraperitoneal infusion pump (IPIP). In future studies, we plan to evaluate efficacies of different drugs in the PM models we have created.

Enhanced BCAT1 activity and BCAA metabolism promotes RhoC activity in cancer progression

Increased expression of branched-chain amino acid transaminase 1 or 2 (BCAT1 and BCAT2) has been associated with aggressive phenotypes of different cancers. Here we identify a gain of function of BCAT1 glutamic acid to alanine mutation at codon 61 (BCAT1E61A) enriched around 2.8% in clinical gastric cancer samples. We found that BCAT1E61A confers higher enzymatic activity to boost branched-chain amino acid (BCAA) catabolism, accelerate cell growth and motility and contribute to tumor development. BCAT1 directly interacts with RhoC, leading to elevation of RhoC activity. Notably, the BCAA-derived metabolite, branched-chain α-keto acid directly binds to the small GTPase protein RhoC and promotes its activity. BCAT1 knockout-suppressed cell motility could be rescued by expressing BCAT1E61A or adding branched-chain α-keto acid. We also identified that candesartan acts as an inhibitor of BCAT1E61A, thus repressing RhoC activity and cancer cell motility in vitro and preventing peritoneal metastasis in vivo. Our study reveals a link between BCAA metabolism and cell motility and proliferation through regulating RhoC activation, with potential therapeutic implications for cancers.

Subtype-specific kinase dependency regulates growth and metastasis of poor-prognosis mesenchymal colorectal cancer

BACKGROUND

Colorectal cancer (CRC) can be divided into four consensus molecular subtypes (CMS), each with distinct biological features. CMS4 is associated with epithelial-mesenchymal transition and stromal infiltration (Guinney et al., Nat Med 21:1350-6, 2015; Linnekamp et al., Cell Death Differ 25:616-33, 2018), whereas clinically it is characterized by lower responses to adjuvant therapy, higher incidence of metastatic spreading and hence dismal prognosis (Buikhuisen et al., Oncogenesis 9:66, 2020).

METHODS

To understand the biology of the mesenchymal subtype and unveil specific vulnerabilities, a large CRISPR-Cas9 drop-out screen was performed on 14 subtyped CRC cell lines to uncover essential kinases in all CMSs. Dependency of CMS4 cells on p21-activated kinase 2 (PAK2) was validated in independent 2D and 3D in vitro cultures and in vivo models assessing primary and metastatic outgrowth in liver and peritoneum. TIRF microscopy was used to uncover actin cytoskeleton dynamics and focal adhesion localization upon PAK2 loss. Subsequent functional assays were performed to determine altered growth and invasion patterns.

RESULTS

PAK2 was identified as a key kinase uniquely required for growth of the mesenchymal subtype CMS4, both in vitro and in vivo. PAK2 plays an important role in cellular attachment and cytoskeletal rearrangements (Coniglio et al., Mol Cell Biol 28:4162-72, 2008; Grebenova et al., Sci Rep 9:17171, 2019). In agreement, deletion or inhibition of PAK2 impaired actin cytoskeleton dynamics in CMS4 cells and, as a consequence, significantly reduced invasive capacity, while it was dispensable for CMS2 cells. Clinical relevance of these findings was supported by the observation that deletion of PAK2 from CMS4 cells prevented metastatic spreading in vivo. Moreover, growth in a model for peritoneal metastasis was hampered when CMS4 tumor cells were deficient for PAK2.

CONCLUSION

Our data reveal a unique dependency of mesenchymal CRC and provide a rationale for PAK2 inhibition to target this aggressive subgroup of colorectal cancer.

A practical spatial analysis method for elucidating the biological mechanisms of cancers with abdominal dissemination in vivo

Elucidation of spatial interactions between cancer and host cells is important for the development of new therapies against disseminated cancers. The aim of this study is to establish easy and useful method for elucidating spatial interactions. In this study, we developed a practical spatial analysis method using a gel-based embedding system and applied it to a murine model of cancer dissemination. After euthanization, every abdominal organ enclosed in the peritoneum was extracted en bloc. We injected agarose gel into the peritoneal cavities to preserve the spatial locations of the organs, including their metastatic niches, and then produced specimens when the gel had solidified. Preservation of the original spatial localization was confirmed by correlating magnetic resonance imaging results with the sectioned specimens. We examined the effects of spatial localization on cancer hypoxia using immunohistochemical hypoxia markers. Finally, we identified the mRNA expression of the specimens and demonstrated the applicability of spatial genetic analysis. In conclusion, we established a practical method for the in vivo investigation of spatial location-specific biological mechanisms in disseminated cancers. Our method can elucidate dissemination mechanisms, find therapeutic targets, and evaluate cancer therapeutic effects.

Molecular characterization of colorectal cancer related peritoneal metastatic disease

A significant proportion of colorectal cancer (CRC) patients develop peritoneal metastases (PM) in the course of their disease. PMs are associated with a poor quality of life, significant morbidity and dismal disease outcome. To improve care for this patient group, a better understanding of the molecular characteristics of CRC-PM is required. Here we present a comprehensive molecular characterization of a cohort of 52 patients. This reveals that CRC-PM represent a distinct CRC molecular subtype, CMS4, but can be further divided in three separate categories, each presenting with unique features. We uncover that the CMS4-associated structural protein Moesin plays a key role in peritoneal dissemination. Finally, we define specific evolutionary features of CRC-PM which indicate that polyclonal metastatic seeding underlies these lesions. Together our results suggest that CRC-PM should be perceived as a distinct disease entity.

Colorectal cancer can lead to the development of peritoneal metastases, which are associated with worse disease outcome. Here, the authors characterize peritoneal metastases from 52 patients using RNA-seq and mutational sequencing and show a distinct molecular subtype.

Non-Invasive Imaging and Scoring of Peritoneal Metastases in Small Preclinical Animal Models Using Ultrasound: A Preliminary Trial

Background: The peritoneum is a common site for the formation of metastases originating from several gastrointestinal and gynecological malignancies. A representative preclinical model to thoroughly explore the pathophysiological mechanisms and to study new treatment strategies is important. A major challenge for such models is defining and quantifying the (total) tumor burden in the peritoneal cavity prior to treatment, since it is preferable to use non-invasive methods. We evaluated ultrasound as a simple and easy-to-handle imaging method for this purpose. Methods: Peritoneal metastases were established in six WAG/Rij rats through i.p. injections of the colon carcinoma cell line CC-531. Using ultrasound, the location, number and size of intraperitoneal tumor nodules were determined by two independent observers. Tumor outgrowth was followed using ultrasound until the peritoneal cancer index (PCI) was ≥8. Interobserver variability and ex vivo correlation were assessed. Results: Visible peritoneal tumor nodules were formed in six WAG/Rij rats within 2–4 weeks after cell injection. In most animals, tumor nodules reached a size of 4–6 mm within 3–4 weeks, with total PCI scores ranging from 10–20. The predicted PCI scores using ultrasound ranged from 11–19 and from 8–18, for observer 1 and 2, respectively, which was quite similar to the ex vivo scores. Conclusions: Ultrasound is a reliable non-invasive method to detect intraperitoneal tumor nodules and quantify tumor outgrowth in a rat model.

The safe and effective intraperitoneal chemotherapy with cathepsin B-specific doxorubicin prodrug nanoparticles in ovarian cancer with peritoneal carcinomatosis

Intraperitoneal (IP) chemotherapy has shown promising efficacy in ovarian cancer with peritoneal carcinomatosis (PC), but in vivo rapid clearance and severe toxicity of free anticancer drugs hinder the effective treatment. Herein, we propose the safe and effective IP chemotherapy with cathepsin B-specific doxorubicin prodrug nanoparticles (PNPs) in ovarian cancer with PC. The PNPs are prepared by self-assembling cathepsin B-specific cleavable peptide (FRRG) and doxorubicin (DOX) conjugates, which are further formulated with pluronic F68. The PNPs exhibit stable spherical structure and cytotoxic DOX is specifically released from PNPs via sequential enzymatic degradation by cathepsin B and intracellular proteases. The PNPs induce cytotoxicity in cathepsin B-overexpressing ovarian (SKOV-3 and HeyA8) and colon (MC38 and CT26) cancer cells, but not in cathepsin B-deficient normal cells in cultured condition. With enhanced cancer-specificity and in vivo residence time, IP injected PNPs efficiently accumulate within PC through two targeting mechanisms of direct penetration (circulation independent) and systemic blood vessel-associated accumulation (circulation dependent). As a result, IP chemotherapy with PNPs efficiently inhibit tumor progression with minimal side effects in peritoneal human ovarian tumor-bearing xenograft (POX) and patient derived xenograft (PDX) models. These results demonstrate that PNPs effectively inhibit progression of ovarian cancer with peritoneal carcinomatosis with minimal local and systemic toxicities by high cancer-specificity and favorable in vivo PK/PD profiles enhancing PC accumulation.

Mouse Models of Peritoneal Carcinomatosis to Develop Clinical Applications

Simple Summary

Peritoneal carcinomatosis mouse models as a platform to test, improve and/or predict the appropriate therapeutic interventions in patients are crucial to providing medical advances. Here, we overview reported mouse models to explore peritoneal carcinomatosis in translational biomedical research.

Abstract

Peritoneal carcinomatosis of primary tumors originating in gastrointestinal (e.g., colorectal cancer, gastric cancer) or gynecologic (e.g., ovarian cancer) malignancies is a widespread type of tumor dissemination in the peritoneal cavity for which few therapeutic options are available. Therefore, reliable preclinical models are crucial for research and development of efficacious treatments for this condition. To date, a number of animal models have attempted to reproduce as accurately as possible the complexity of the tumor microenvironment of human peritoneal carcinomatosis. These include: Syngeneic tumor cell lines, human xenografts, patient-derived xenografts, genetically induced tumors, and 3D scaffold biomimetics. Each experimental model has its own strengths and limitations, all of which can influence the subsequent translational results concerning anticancer and immunomodulatory drugs under exploration. This review highlights the current status of peritoneal carcinomatosis mouse models for preclinical development of anticancer drugs or immunotherapeutic agents.

A genome-wide study of the relationship between chromosomal abnormalities and gene expression in colorectal tumors

The role of somatic copy number alterations (SCNAs) that occur in colorectal tumors is poorly understood. SCNAs are correlated with corresponding gene expression changes that may contribute to neoplastic progression. Thus, we examined SCNAs and the expression of messenger RNAs (mRNAs) located at corresponding loci in colorectal neoplasia, a progression model of human neoplasm. We used 42 colorectal neoplastic samples, including adenomas, intramucosal cancers (IMC) and invasive colorectal cancers (CRC) that were microsatellite stable (MSS) using a genome-wide SNP array and gene expression array (first cohort). In addition, validation analyses were examined (37 colorectal neoplasias). None of the mRNAs with a corresponding SCNA was found in the adenomas. However, three mRNAs, including ARFGEF2 at 20q13.13, N4BP2L2 at 13q13.1 and OLFM4 at 13q14.3 with a copy number (CN) gain at the corresponding locus were upregulated in IMCs of the first cohort. Moreover, upregulated expression of ARFGEF2 and OLFM4 was upregulated in the validation analysis. Finally, 28 mRNAs with gains of corresponding loci were pooled in invasive CRC of the first cohort. The mRNAs, including ACSS2 (20q11.22), DDX27 (20q13.13), MAPRE1 (20q11.21), OSBPL2 (20q11.22) and PHF20 (20q11.22-q11.23) with CN gains of the corresponding loci were identified in 28 mRNAs. Four of these mRNAs (DDX27, MAPRE1, OSBPL2 and PHF20) were upregulated in the invasive CRC in the validation analysis. We conclude that specific 13q and 22q CN gains with gene expression changes in the corresponding loci may play an important role in IMC cells' progression into invasive CRC.