The role played by bacterial infections in the onset and metastasis of cancer

Enterococcus faecalis co-cultured with oral cancer cells exhibits higher virulence and promotes cancer cell survival, proliferation, and migration: an in vitro study

Introduction. Enterococcus faecalis is a common pathogen associated with many oral diseases and is often isolated from oral cancer patients. However, limited information is available on its key virulence gene expression in oral cancer cell microenvironment and cancer cell behaviour in co-culture studies.Hypothesis. E. faecalis overexpresses virulence genes when co-cultured with oral cancer cells and possibly alters the tumour microenvironment, promoting oral cancer proliferation and survival.Aim. To investigate altered virulence gene expression in E. faecalis and oral cancer cell behaviour using in vitro co-culture experiments.Methodology. Cal27 cells were co-cultured with E. faecalis and assessed for their cell proliferation, apoptosis, migration and clonogenicity using standard cell culture assays. The levels of reactive oxygen species (ROS) and inflammatory cytokines, along with proliferative, angiogenic and apoptotic biomarker expressions, were also assessed. E. faecalis adherence to cancer cells was demonstrated by the gentamicin protection assay. Real time-PCR was used to analyse the expression of virulence genes.Results. Co-culture of Cal27 cells with E. faecalis showed significantly higher cell proliferation, migration and clonogenicity compared to the control (P<0.01). A significant increase in the levels of ROS and inflammatory cytokines and overexpression of Ki67, vascular endothelial growth factor, extracellular signal-regulated kinase 1/2, phosphoinositide 3 kinase and Akt was observed in the co-culture group. E. faecalis also downregulated p53 and Bax genes while upregulated Bcl-2. The virulence genes GelE, Asa and Ace were overexpressed in E. faecalis co-cultured with Cal27 cells.Conclusion. The results from this study indicate the possible risks of E. faecalis infection in oral cancer. An effective antibiotic strategy against E. faecalis to prevent complications associated with oral diseases, including cancer, is needed.

Microbiota-induced inflammatory responses in bladder tumors promote epithelial-mesenchymal transition and enhanced immune infiltration

The intratumoral microbiota can modulate the tumor immune microenvironment (TIME); however, the underlying mechanism by which intratumoral microbiota influences the TIME in urothelial carcinoma of the bladder (UCB) remains unclear. To address this, we collected samples from 402 patients with UCB, including paired host transcriptome and tumor microbiome data, from The Cancer Genome Atlas (TCGA). We found that the intratumoral microbiome profiles were significantly correlated with the expression pattern of epithelial-mesenchymal transition (EMT)-related genes. Furthermore, we detected that the genera Lachnoclostridium and Sutterella in tumors could indirectly promote the EMT program by inducing an inflammatory response. Moreover, the inflammatory response induced by these two intratumoral bacteria further enhanced intratumoral immune infiltration, affecting patient survival and response to immunotherapy. In addition, an independent immunotherapy cohort of 348 patients with bladder cancer was used to validate our results. Collectively, our study elucidates the potential mechanism by which the intratumoral microbiota influences the TIME of UCB and provides a new guiding strategy for the targeted therapy of UCB.NEW & NOTEWORTHY The intratumoral microbiota may mediate the bladder tumor inflammatory response, thereby promoting the epithelial-mesenchymal transition program and influencing tumor immune infiltration.

Global transcriptomic analysis of breast cancer and normal mammary epithelial cells infected with Borrelia burgdorferi

The bacterial spirochete Borrelia burgdorferi, the causative agent of Lyme Disease, can disseminate and colonize various tissues and organs, orchestrating severe clinical symptoms including arthritis, carditis, and neuroborreliosis. Previous research has demonstrated that breast cancer tissues could provide an ideal habitat for diverse populations of bacteria, including B. burgdorferi, which is associated with a poor prognosis. Recently, we demonstrated that infection with B. burgdorferi enhances the invasion and migration of triple-negative MDA-MB-231 cells which represent a type of breast tumor with more aggressive cancer traits. In this study, we hypothesized that infection by B. burgdorferi affects the expression of cancer-associated genes to effectuate breast cancer phenotypes. We applied the high-throughput technique of RNA-sequencing on B. burgdorferi-infected MDA-MB-231 breast cancer and normal-like MCF10A cells to determine the most differentially expressed genes (DEG) upon infection. Overall, 142 DEGs were identified between uninfected and infected samples in MDA-MB-231 while 95 DEGs were found in MCF10A cells. A major trend of the upregulation of C-X-C and C-C motif chemokine family members as well as genes and pathways was associated with infection, inflammation, and cancer. These genes could serve as potential biomarkers for pathogen-related tumorigenesis and cancer progression which could lead to new therapeutic opportunities.

Control of Helicobacter pylori with engineered probiotics secreting selective guided antimicrobial peptides

Helicobacter pylori is the primary cause of 78% of gastric cancer cases, providing an opportunity to prevent cancer by controlling a single bacterial pathogen within the complex gastric microbiota. We developed highly selective antimicrobial agents against H. pylori by fusing an H. pylori-binding guide peptide (MM1) to broad-spectrum antimicrobial peptides. The common dairy probiotic Lactococcus lactis was then engineered to secrete these guided antimicrobial peptides (gAMPs). When co-cultured in vitro with H. pylori, the gAMP probiotics lost no toxicity compared to unguided AMP probiotics against the target, H. pylori, while losing >90% of their toxicity against two tested off-target bacteria. To test binding to H. pylori, the MM1 guide was fused to green fluorescent protein (GFP), resulting in enhanced binding compared to unguided GFP as measured by flow cytometry. In contrast, MM1-GFP showed no increased binding over GFP against five different off-target bacteria. These highly selective gAMP probiotics were then tested by oral gavage in mice infected with H. pylori. As a therapy, the probiotics outperformed antibiotic treatment, effectively eliminating H. pylori in just 5 days, and also protected mice from challenge infection as a prophylactic. As expected, the gAMP probiotics were as toxic against H. pylori as the unguided AMP probiotics. However, a strong rebound in gastric species diversity was found with both the selective gAMP probiotics and the non-selective AMP probiotics. Eliminating the extreme microbial dysbiosis caused by H. pylori appeared to be the major factor in diversity recovery. IMPORTANCE Alternatives to antibiotics in the control of Helicobacter pylori and the prevention of gastric cancer are needed. The high prevalence of H. pylori in the human population, the induction of microbial dysbiosis by antibiotics, and increasing antibiotic resistance call for a more sustainable approach. By selectively eliminating the pathogen and retaining the commensal community, H. pylori control may be achieved without adverse health outcomes. Antibiotics are typically used as a therapeutic post-infection, but a more targeted, less disruptive approach could be used as a long-term prophylactic against H. pylori or, by extension, against other gastrointestinal pathogens. Furthermore, the modular nature of the guided antimicrobial peptide (gAMP) technology allows for the substitution of different guides for different pathogens and the use of a cocktail of gAMPs to avoid the development of pathogen resistance.

Gut colonization with an obesity-associated enteropathogenic microbe modulates the premetastatic niches to promote breast cancer lung and liver metastasis

Introduction

Obesity, an independent risk factor for breast cancer growth and metastatic progression, is also closely intertwined with gut dysbiosis; and both obese state and dysbiosis promote each other. Enteric abundance of Bacteroides fragilis is strongly linked with obesity, and we recently discovered the presence of B. fragilis in malignant breast cancer. Given that enterotoxigenic B. fragilis or ETBF, which secretes B. fragilis toxin (BFT), has been identified as a procarcinogenic microbe in breast cancer, it is necessary to examine its impact on distant metastasis and underlying systemic and localized alterations promoting metastatic progression of breast cancer.

Methods

We used syngeneic mammary intraductal (MIND) model harboring gut colonization with ETBF to query distant metastasis of breast cancer cells. Alterations in the immune network and cytokines/chemokines in the tumor microenvironment and distant metastatic sites were examined using flow cytometry, immunohistochemistry, and multiplex arrays.

Results

ETBF infection initiates a systemic inflammation aiding in the establishment of the premetastatic niche formation in vital organs via increased proinflammatory and protumorigenic cytokines like IL17A, IL17E, IL27p28, IL17A/F, IL6, and IL10 in addition to creating a prometastatic immunosuppressive environment in the liver and lungs rich in myeloid cells, macrophages, and T regulatory cells. It induces remodeling of the tumor microenvironment via immune cell and stroma infiltration, increased vasculogenesis, and an EMT-like response, thereby encouraging early metastatic dissemination ready to colonize the conducive environment in liver and lungs of the breast tumor-bearing mice.

Discussion

In this study, we show that enteric ETBF infection concomitantly induces systemic inflammation, reshapes the tumor immune microenvironment, and creates conducive metastatic niches to potentiate early dissemination and seeding of metastases to liver and lung tissues in agreement with the "seed and soil hypothesis." Our results also support the ETBF-induced "parallel model" of metastasis that advocates for an early dissemination of tumor cells that form metastatic lesions independent of the primary tumor load.

A rare case of colorectal metastasis found 8 years and 10 months after gastrectomy for advanced gastric cancer: A case report and literature review

Colorectal metastasis from gastric cancer is rare and may develop several years after gastric cancer surgery. Therefore, colonoscopic findings provide useful diagnostic information. The present report describes a case of gastric cancer colon metastasis diagnosed 8 years and 10 months after gastrectomy for advanced gastric cancer. A 64-year-old male patient underwent gastrectomy in December 2010 and received chemotherapy for 4 years and 10 months after the surgery. Subsequently, the patient was diagnosed as having colorectal cancer by computed tomography in February 2019. Colonoscopy revealed linitis plastica-like colon stenosis; however, biopsy pathology did not reveal any findings indicating malignancy. Right hemicolectomy was performed, and pathological examination revealed colon metastasis from gastric cancer. The patient received chemotherapy but died of peritoneal carcinomatosis 1 year and 8 months after the colectomy. According to literature, colorectal metastasis from gastric cancer is often attributed to hematogenous metastasis and often exhibits characteristic macroscopic features. Treatments, such as chemotherapy for gastric cancer and/or colorectal resection, are considered effective for gastric cancer colorectal metastasis.

Discovery of new symmetrical and asymmetrical nitrile-containing 1,4-dihydropyridine derivatives as dual kinases and P-glycoprotein inhibitors: synthesis, in vitro assays, and in silico studies

Two new series of symmetric (1a-h) and asymmetric (2a-l) 1,4-DHP derivatives were designed, synthesised, and evaluated as anticancer agents. In vitro anticancer screening of target compounds via National cancer institute “NCI” revealed that analogues 1g, 2e, and 2l demonstrated antiproliferative action with mean growth inhibition percentage “GI%” = 41, 28, and 64, respectively. The reversal doxorubicin (DOX) effects of compounds 1g, 2e, and 2l were examined and illustrated better cytotoxic activity with IC₅₀ =1.12, 3.64, and 3.57 µM, respectively. The most active anticancer analogues, 1g, 2e, and 2l, were inspected for their putative mechanism of action by estimating their epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER-2), and Bruton’s tyrosine kinase (BTK) inhibitory activities. Furthermore, the antimicrobial activity of target compounds was assessed against six different pathogens, followed by determining the minimum inhibitory concentration “MIC” values for the most active analogues. Molecular docking study was achieved to understand mode of interactions between selected inhibitors and different biological targets.

Tumor microbiome metabolism: A game changer in cancer development and therapy

Accumulating recent evidence indicates that the human microbiome plays essential roles in pathophysiological states, including cancer. The tumor microbiome, an emerging concept that has not yet been clearly defined, has been proven to influence both cancer development and therapy through complex mechanisms. Small molecule metabolites produced by the tumor microbiome through unique biosynthetic pathways can easily diffuse into tissues and penetrate cell membranes through transporters or free diffusion, thus remodeling the signaling pathways of cancer and immune cells by interacting with biomacromolecules. Targeting tumor microbiome metabolism could offer a novel perspective for not only understanding cancer progression but also developing new strategies for the treatment of multiple cancer types. Here, we summarize recent advances regarding the role the tumor microbiome plays as a game changer in cancer biology. Specifically, the metabolites produced by the tumor microbiome and their potential effects on the cancer development therapy are discussed to understand the importance of the microbial metabolism in the tumor microenvironment. Finally, new anticancer therapeutic strategies that target tumor microbiome metabolism are reviewed and proposed to provide new insights in clinical applications.

Injectable Thermosensitive Iodine-Loaded Starch-g-poly(N-isopropylacrylamide) Hydrogel for Cancer Photothermal Therapy and Anti-Infection

Although photothermal therapy (PTT) can effectively eliminate tumors, the normal tissues near tumors are inevitably damaged by heat and infected by bacteria, which greatly limits the therapeutic effect. In this work, an injectable thermosensitive hydrogel based on iodine-loaded starch-g-poly(N-isopropylacrylamide) (PNSI) is developed to overcome this problem. FTIR, ¹ H NMR and UV-Vis spectra confirm the graft copolymerization of poly(N-isopropylacrylamide) with starch and the formation of "iodine-starch" complex. TEM images show PNSI polymer self-assembles into regular spherical nanogel with a size of ∼50 nm. The concentrated nanogel dispersion is a sol at room temperature and transforms to hydrogel at body temperature. Under NIR laser irradiation for 10 mins, the ΔT of the nanogel dispersion approachs about 20°C with excellent thermal stability and high cytotoxicity due to the photothermal effect of the "iodine-starch" complex. After intratumor injection, this injectable hydrogel efficiently inhibites the tumor growth using 808 nm laser irradiation. Furthermore, it can also suppress S. aureus infection in the wound post PTT due to the release of iodine, which promotes wound healing. Therefore, this injectable thermosensitive "iodine-starch" composite hydrogel with advantages of good biocompatible and easy preparation possesses potential application for tumor photothermal therapy and anti-bacterial infection. This article is protected by copyright. All rights reserved.