Bacterial systems for gene delivery to systemic tumors

Intratumoral levels and prognostic significance of Fusobacterium nucleatum in cervical carcinoma

Growing evidence suggests that microbes can influence the onset of cancer and its consequent development. By researching samples from patients afflicted by cervical cancer, we aimed to explore the associated dynamics and prognostic value of intratumoral levels of F. nucleatum. We used qPCR to analyze tumor tissues obtained from 112 cervical cancer patients in order to characterize the levels and influences of intratumoral levels of the F. nucleatum. Especially for recurrent tissues, there was a distinct observation of higher levels of F. nucleatum in cervical cancer. Patients with high burdens of F. nucleatum intratumoral infiltration exhibited correspondingly poor rates of both overall survival and progression-free survival. Measures of the levels of F. nucleatum were found to have been reliable independent prognostic factors that could predict rates of PFS for afflicted patients (HR = 4.8, 95%CI = 1.2-18.6, P = 0.024). Notably, the levels ofF. nucleatum were positively correlated with tumor differentiation. Cancer cells from patients with relatively high levels of F. nucleatum were observed to possess the characteristics of cancer stem cells (CSCs). We propose that F. nucleatum might be one potential cervical cancer diagnostic and prognostic biomarker, and these findings will help to provide a sound rationale and merit for further study of this bacterium.

Gut microbiota-stimulated cathepsin K secretion mediates TLR4-dependent M2 macrophage polarization and promotes tumor metastasis in colorectal cancer

Metastasis is a complex process that requires the interaction between tumor cells and their microenvironment. As an important regulator of intestinal microenvironment, gut microbiota plays a significant role in the initiation and progression of colorectal cancer (CRC), but the underlying mechanisms remain elusive. In this study, a metastasis-related secretory protein cathepsin K (CTSK) was identified as a vital mediator between the imbalance of intestinal microbiota and CRC metastasis. We implanted MC38 cells into the cecal mesentry of antibiotic-treated mice with intragastrically administration of E. coli to mimic gut microbiota imbalance. The bigger primary tumors and more liver metastatic foci were detected in the E. coli group accompanied with high LPS secretion and CTSK overexpression compared with that in the control group. CTSK contributes to the aggressive phenotype of CRC cells both in vitro and in vivo. Silencing CTSK or administration of Odanacatib, a CTSK-specific inhibitor, totally abolished the CTSK-enhanced migration and motility of CRC cells. Interestingly, the tumor-secreted CTSK could bind to toll-like receptor 4 (TLR4) to stimulate the M2 polarization of tumor-associated macrophages (TAMs) via an mTOR-dependent pathway. Recombinant CTSK could neither stimulate CRC growth and metastasis, nor induce M2 macrophage polarization in TRL4^-/- mice. Meanwhile, CTSK could stimulate the secretion of cytokines by M2 TAMs including IL10 and IL17, which, in turn, promote the invasion and metastasis of CRC cells through NFκB pathway. Clinically, overexpression of CTSK in human CRC tissues is always accompanied with high M2 TAMs in the stroma, and correlated with CRC metastasis and poor prognosis. Our current research identified CTSK as a mediator between the imbalance of gut microbiota and CRC metastasis. More importantly, we illustrated a CTSK-mediated-positive feedback loop between CRC cells and TAMs during metastasis, prompting CTSK as a novel predictive biomarker and feasible therapeutic target for CRC.

Local bacteria affect the efficacy of chemotherapeutic drugs

In this study, the potential effects of bacteria on the efficacy of frequently used chemotherapies was examined. Bacteria and cancer cell lines were examined in vitro and in vivo for changes in the efficacy of cancer cell killing mediated by chemotherapeutic agents. Of 30 drugs examined in vitro, the efficacy of 10 was found to be significantly inhibited by certain bacteria, while the same bacteria improved the efficacy of six others. HPLC and mass spectrometry analyses of sample drugs (gemcitabine, fludarabine, cladribine, CB1954) demonstrated modification of drug chemical structure. The chemoresistance or increased cytotoxicity observed in vitro with sample drugs (gemcitabine and CB1954) was replicated in in vivo murine subcutaneous tumour models. These findings suggest that bacterial presence in the body due to systemic or local infection may influence tumour responses or off-target toxicity during chemotherapy.