Crosstalk Between the Intratumoral Microbiota and the Tumor Microenvironment: New Frontiers in Solid Tumor Progression and Treatment

Abstract

Background: The microbiota plays a significant role in the tumor microenvironment, and its impact on tumor development and treatment outcome cannot be overlooked. Thus, it is essential to comprehend the interactions between the microbiota and the tumor microenvironment.

Recent findings: With the advent of next-generation sequencing, microbiota research has advanced significantly in recent years. The interaction between the intratumoral microbiota and the tumor microenvironment is an emerging area of research that holds great promise for understanding and treating solid tumor progression. This crosstalk between the intratumoral microbiota and the tumor microenvironment is a complex process that involves a multitude of factors, including the immune system, cellular signaling pathways, and metabolic processes. The origin of the intratumoral microbiota differs between various solid tumor, and the quantity and diversity of intratumoral microbiota also fluctuate significantly within each solid tumor.

Conclusion: The aim of this review is to provide a detailed summary of the intratumoral microbiota in various types of solid tumors. This will include an analysis of their origins, differences, and how they impact the progression of solid tumors. Furthermore, we will emphasize the significant potential that the intratumoral microbiota holds for the diagnosis and treatment of solid tumors.

Keywords: intratumoral microbiota; origins; progression; solid tumors; treatment.

FIGURE 1

Possible explanations for the origin of intratumoral microbiota in solid tumors. (A) suggests that microbiota from oral and intestinal mucosa enter tumors by disrupting the mucosal barrier. (B) proposes that intratumoral microbiota originates from NAT, as seen in pancreatic cancer where the intratumoral microbiota is highly similar to the microbiota in the stomach, intestine, and liver. (C) suggests that microbiota can enter tumor cells through the circulatory system, as microbiota from the oral cavity and intestinal tract can reach various parts of the body through the blood circulation and invade tumor cells through damaged blood vessels.

FIGURE 2

The intratumoral microbiota and TME interact to promote tumor initiation and progression, mainly involving the following five main steps. (A) Formation of an immunosuppressive microenvironment. (B) DNA damage. (C) Activation of oncogenic pathways. (D) Induction of chronic inflammation. (E) Epigenetic modifications.

FIGURE 3

Clinical application of intratumoral microbiota in the treatment of solid tumors. (A) Microbiota ablation technology. (A) involves using antibiotics to kill harmful microbiota and improve the effectiveness of cancer treatment. (B) Engineering microbiota therapeutics. The second approach is to engineer microbiota therapeutics, which can directly target cancer cells or serve as a drug carrier for combined therapy. (C) Oncolytic virus. Utilize the technology and principle of oncolytic virus to directly or indirectly enhance the immune response for the treatment of solid tumors.