Cancer killers in the human gut microbiota: diverse phylogeny and broad spectra

Abstract

Cancer as a large group of complex diseases is believed to result from the interactions of numerous genetic and environmental factors but may develop in people without any known genetic or environmental risks, suggesting the existence of other powerful factors to influence the carcinogenesis process. Much attention has been focused recently on particular members of the intestinal microbiota for their potential roles in promoting carcinogenesis. Here we report the identification and characterization of intestinal bacteria that exhibited potent anti-malignancy activities on a broad range of solid cancers and leukemia. We collected fecal specimens from healthy individuals of different age groups (preschool children and university students), inspected their effects on cancer cells, and obtained bacteria with potent anti-malignancy activities. The bacteria mostly belonged to Actinobacteria but also included lineages of other phyla such as Proteobacteria and Firmicutes. In animal cancer models, sterile culture supernatant from the bacteria highly effectively inhibited tumor growth. Remarkably, intra-tumor administration of the bacterial products prevented metastasis and even cleared cancer cells at remote locations from the tumor site. This work demonstrates the prevalent existence of potent malignancy-killers in the human intestinal microbiota, which may routinely clear malignant cells from the body before they form cancers.

The Intestinal Microbiota in Colorectal Cancer

“…Probiotics such as VSL#3 affected microbial composition but failed to reduce colitis-associated CRC (Arthur et al, 2013). However, Actinobacteria (e.g., Streptomyces), Proteobacteria (e.g., Acinetobacter), and Firmicutes (e.g., Brevibacterium or Bacillus) might exert anti-carcinogenic effects (Zhou et al, 2017). Dietary components might be suitable to modulate the intestinal microbiota probably by promoting a large microbial diversity.…”

Functional Genomics Insights Into the Pathogenicity, Habitat Fitness, and Mechanisms Modifying Plant Development of Rhodococcus sp. PBTS1 and PBTS2

“…Although R. corynebacterioides strains have not been studied extensively, they have been reported as endophytes from the xylem of eggplant and the leaves of Arabidopsis thaliana (Traw et al, 2007;Achari and Ramesh, 2014), inhabitants of the phyllosphere of apples (He et al, 2012), and as efficient degraders of aflatoxin (formerly Flavobacterium aurantiacum; Teniola et al, 2005;Risa et al, 2018), oil (Bayat et al, 2015), and rubber products (Pan et al, 2009). They have also been described as the cause of various infections in patients (Al Akhrass et al, 2012;Kitamura et al, 2012;Vergidis et al, 2017;Khalil et al, 2019) and as cancer killers exhibiting potent anti-malignancy activity (Zhou et al, 2017). In contrast, PBTS2 isolates grouped together with R. fascians (Stamler et al, 2015b).…”

Invertebrates living in polluted environments are potential source of novel anticancer agents

“…Although, recent studies have tested human gut microbiota for anticancer agents [14,15], to our knowledge, this is the first study to mine gut bacteria of selected invertebrates for potential anticancer molecules. Zhou et al, [15] revealed the anticancer activity of gut bacteria isolated from the fecal sample of a group of healthy individuals; preschool children and university students.…”

“…Although, recent studies have tested human gut microbiota for anticancer agents [14,15], to our knowledge, this is the first study to mine gut bacteria of selected invertebrates for potential anticancer molecules. Zhou et al, [15] revealed the anticancer activity of gut bacteria isolated from the fecal sample of a group of healthy individuals; preschool children and university students. If bacteria isolated from humans can possess anticancer properties, it is logical to speculate that pests that thrive in polluted environments and are able to withstand high levels of radiation may contribute to the resistance of cancer development in the host species [13,16].…”