Next-generation probiotics - do they open new therapeutic strategies for cancer patients?

Gut microbiota and its association with cancer development/treatment has been intensively studied during the past several years. Currently, there is a growing interest toward next-generation probiotics (NGPs) as therapeutic agents that alter gut microbiota and impact on cancer development. In the present review we focus on three emerging NGPs, namely Faecalibacterium prausnitzii, Akkermansia muciniphila, and Bacteroides fragilis as their presence in the digestive tract can have an impact on cancer incidence. These NGPs enhance gastrointestinal immunity, maintain intestinal barrier integrity, produce beneficial metabolites, act against pathogens, improve immunotherapy efficacy, and reduce complications associated with chemotherapy and radiotherapy. Notably, the use of NGPs in cancer patients does not have a long history and, although their safety remains relatively undefined, recently published data has shown that they are non-toxigenic. Notwithstanding, A. muciniphila may promote colitis whereas enterotoxigenic B. fragilis stimulates chronic inflammation and participates in colorectal carcinogenesis. Nevertheless, the majority of B. fragilis strains provide a beneficial effect to the host, are non-toxigenic and considered as the best current NGP candidate. Overall, emerging studies indicate a beneficial role of these NGPs in the prevention of carcinogenesis and open new promising therapeutic options for cancer patients.

Identification of a Stable, Non-Canonically Regulated Nrf2 Form in Lung Cancer Cells.

Nrf2 (nuclear factor erythroid 2 (NF-E2)-related factor 2) transcription factor is recognized for its pro-survival and cell protective role upon exposure to oxidative, chemical, or metabolic stresses. Nrf2 controls a number of cellular processes such as proliferation, differentiation, apoptosis, autophagy, lipid synthesis, and metabolism and glucose metabolism and is a target of activation in chronic diseases like diabetes, neurodegenerative, and inflammatory diseases. The dark side of Nrf2 is revealed when its regulation is imbalanced (e.g., via oncogene activation or mutations) and under such conditions constitutively active Nrf2 promotes cancerogenesis, metastasis, and radio- and chemoresistance. When there is no stress, Nrf2 is instantly degraded via Keap1-Cullin 3 (Cul3) pathway but despite this, cells exhibit a basal activation of Nrf2 target genes. It is yet not clear how Nrf2 maintains the expression of its targets under homeostatic conditions. Here, we found a stable 105 kDa Nrf2 form that is resistant to Keap1-Cul3-mediated degradation and translocates to the nucleus of lung cancer cells. RNA-Seq analysis indicate that it might originate from the exon 2 or exon 3-truncated transcripts. This stable 105 kDa Nrf2 form might help explain the constitutive activity of Nrf2 under normal cellular conditions.

Proteogenomic Platform for Identification of Tumor Specific Antigens.

BACKGROUND: Although immune responses to “cancer neoantigens” have been known for decades, the first neoantigen vaccines emerged only very recently. Current developments in genomics and proteomics have enabled descriptions of tumor mutational landscapes, and the immunogenicity of corresponding neoantigens can now be predicted either in silico or in vitro. Cancer regression could be achieved via a combination of neoantigen vaccination and an appropriate immunology approach. Research in model organisms and the results of initial clinical trials of neoantigen vaccines have shown them to be effective. PURPOSE: We aim to emphasize the importance of neoantigen vaccines in personalized cancer treatment and describe their preparation. We summarize mutations leading to expression of an immunogenic antigen necessary for vaccine development. The processes leading to activation of T-cell anticancer immunity in a patient are briefly introduced. We especially focus on the identification of high confidence neoantigens by next-generation sequencing (NGS) and mass spectrometry (MS), which is key element in the process of designing neoantigen vaccines. Briefly, we describe a proteogenomic platform for confident identification of mutant peptides in biological material. We mention the possibility of neoantigen quantification in biological material using mass spectrometry such as SRM (selected reaction monitoring) and SWATH (sequential windowed acquisition of all theoretical fragment ion spectra). Successful clinical studies demonstrating the potential of neoantigen vaccination in personalized cancer treatment are summarized at the end of the paper. Key words: vaccination - mass spectrometry - neoplasms - organ-specific neoantigen This work was supported by the project MEYS - NPS I - LO1413. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Accepted: 9. 7. 2018.