Veillonella parvula as an anaerobic lactate-fermenting bacterium - for inhibition of tumor growth and metastasis through tumor-specific colonization and decrease of tumor’s lactate level

Q: Why is tumor lactate targeted in cancer treatment?

High tumor lactate is directly linked to tumor growth, metastasis, and poor prognosis, and it supports an acidic microenvironment that promotes aggressive behavior and treatment resistance.

Q: How was Veillonella parvula administered and how was the best route selected?

4T1 breast tumor-bearing BALB/c mice received V. parvula intravenously, orally, intraperitoneally, and intratumorally. Biodistribution was evaluated to choose the route with the best tumor colonization, followed by safety assessment.

Q: What outcomes did Veillonella parvula produce in tumor lactate and metastasis?

Tumor colonization by V. parvula significantly decreased tumor lactate level (about 46% vs controls). The treatment group also showed reduced liver metastasis and inhibition of cancer cell proliferation based on Ki-67 staining.

Sep 21, 2026

Uploaded by Asher

High tumor lactate level is associated with tumor growth, metastasis, and poor patient prognosis, motivating lactate-targeting cancer strategies. This study uses the strictly anaerobic lactate-fermenting bacterium Veillonella parvula to reduce tumor lactate. 4T1 tumor-bearing BALB/c mice received V. parvula via multiple routes, then biodistribution and safety were assessed. The optimal route was used to evaluate in vivo effects on tumor growth, liver metastasis, histology, immunohistochemistry, and lactate level. V. parvula showed strong tumor colonization and safety.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages10

Reading Time25 min

AccessFree to download

Background and Rationale

Experimental Design and Administration Routes

Biodistribution and Safety Assessment

Therapeutic Effects on Tumor Growth and Metastasis

Histopathology, Immunohistochemistry, and Lactate Measurement

Key Findings and Conclusions

[www. nature.com/scientificreports](www. nature.com/scientificreports) OPEN Veillonella parvula as an anaerobic lactate‑fermenting bacterium for inhibition of tumor growth and metastasis through tumor‑specific colonization and decrease of tumor’s lactate level Amirhosein Kefayat1, Mahshid Bahrami2, Mojtaba Karami3, Soodabeh Rostami4 & FatemehGhahremani5* High tumor’s lactate level directly associates with high tumor growth, metastasis, and patients’poor prognosis. Therefore, many studies have focused on the decrease of tumor’s lactate as a novel cancer treatment. In the present study for the first time, a strictly anaerobic lactate‑fermenting bacterium, Veillonella parvula, was employed for the decrease of tumor’s lactate level. At first, 4T1 breast tumor‑bearing BALB/c mice were administered with 106 V. parvula bacteria intravenously, orally, intraperitoneally, and intratumorally. Then, the bacteria biodistribution was evaluated. The best administration route according to tumor colonization was selected and its safety was assessed. Then, the therapeutic effect of V. parvula administration through the best route was investigated according to 4T1 murine breast tumor’s growth and metastasis in vivo. In addition, histopathological and immunohistochemistry evaluations were done to estimate microscopic changes atthe inner of the tumor and tumor’s lactate level was measured after V. parvula administration. V. parvula exhibited considerable tumor‑targeting and colonization efficacy, 24 h after intravenous administration. Normal organs were free of the bacteria after 72 h and no side effect was observed. Tumor colonization by V. parvula significantly decreased the tumors’ lactate level for about 46% in comparison with control tumors which caused 44.3% and 51.6% decline (P < 0.05) in the mean tumors’volume and liver metastasis of the treatment group in comparison with the control group, respectively. The treatment group exhibited 35% inhibition in the cancer cell proliferation in comparison with the control according to the Ki‑67 immunohistochemistry staining. Therefore, intravenous administration of V. parvula is a tumor‑specific and safe treatment which can significantly inhibit tumors’ growth and metastasis by decreasing the tumor lactate level. Keywords Breast cancer, Bacteria therapy, Veillonella parvula, Lactate 1Department of Oncology, Isfahan University of Medical Sciences, Isfahan 81746-73461, Iran. 2Department of Radiology, Isfahan University of Medical Sciences, Isfahan, Iran. 3Department of Dermatology, Tehran University of Medical Sciences, Tehran, Iran. 4Nosocomial Infection Research Center, Isfahan University of Medical Sciences, Isfahan 81746-73461, Iran. 5Department of Medical Physics and Radiotherapy, Arak University of Medical Sciences, Sardasht, Meydan Basij, Arāk 38481-76941, Iran.* email: [bahare.ghahremani@gmail.com](bahare.ghahremani@gmail.com); f.ghahramani@ [arakmu.ac.ir](arakmu.ac.ir) [www. nature.com/scientificreports/](www. nature.com/scientificreports/) Abbreviations V. parvulai.v i.p i.t CFUs H&E Veillonella parvula Intravenous Intraperitoneal Intratumoral Colony forming units Hematoxylin and eosin Breast cancer is the leading cause of cancer-related deaths among women, worldwide1. Although breast cancer treatments have achieved considerable improvements in recent years, patients’ prognosis is not satisfying yet, especially for metastatic breast cancer. Metastasis is the most pernicious behavior of cancer cells and it is responsible for more than 90% of cancer patients’ death2. Neoplasms arise from malignant transformations of normal cells which cause gaining specific features and abilities like limitless growth and proliferation, avoidance of apoptosis, sustained angiogenesis, metastasis, and specific metabolic pathways in the cancer cells3. Uncontrolled growth and proliferation of cancer cells is highly energy consuming and need biomaterials4. To carry out these nee

FAQs

Why is tumor lactate targeted in cancer treatment?

High tumor lactate is directly linked to tumor growth, metastasis, and poor prognosis, and it supports an acidic microenvironment that promotes aggressive behavior and treatment resistance.

How was Veillonella parvula administered and how was the best route selected?

4T1 breast tumor-bearing BALB/c mice received V. parvula intravenously, orally, intraperitoneally, and intratumorally. Biodistribution was evaluated to choose the route with the best tumor colonization, followed by safety assessment.

What outcomes did Veillonella parvula produce in tumor lactate and metastasis?

Tumor colonization by V. parvula significantly decreased tumor lactate level (about 46% vs controls). The treatment group also showed reduced liver metastasis and inhibition of cancer cell proliferation based on Ki-67 staining.

Sep 21, 2026

Uploaded by Asher