Title: Expression and content of the LC3B protein in gastric cancers, relationship to mTOR, AMPK expression, clinical and morphological parameters, and the tumor response to neoadjuvant chemotherapy

Abstract

Background. Autophagy plays a dual role in oncogenesis processes. On the one hand, increasing the cell's resistance to oncogenic factors, and on the other hand, participating in the processes of tumor progression and the formation of resistance to antitumor treatment. It has been shown that autophagy correlates with the aggressive course of the disease and its poor prognosis. The molecular cascades that regulate autophagy are numerous and varied and play a role in tumorigenesis that has not yet been studied.The study aimed to study the expression of LC3B, mTOR, AMPK, the content of the LC3B protein in gastric cancer tissue, and its relationship with disease progression, and the response to anti-cancer therapy.Material and methods. The study included 34 patients with morphologically verified gastric cancer. All patients were hospitalized in the Department of Abdominal Oncology of the TNIMTs Research Institute of Oncology. All patients had FLOT neoadjunvant chemotherapy (NACT) (fluorouracil, leucovorin, oxaliplatin, and docetaxel) followed the gastrectomy. The response to the combined treatment of patients was evaluated according to the RECIST 1.1 criteria.The study's material was the non-transformed and tumor tissues obtained during diagnostic video gastroscopy in patients before the start of combined treatment and after surgical treatment, frozen after collection and stored at t -800C. The expression of LC3B, mTOR, AMPK was determined by real-time PCR, the LC3B protein level - using the Western Blotting method.Results and their discussion. The mRNA level and the content of the LC3B protein are associated with the size of the tumor, damage to regional lymph nodes (spread of the disease), and the presence of cricoid cells. The AMPK mRNA level increased in patients with the T4N0-2M0 stage in 37.7 and 7.33 times, respectively, compared with patients with the T2N0M0 and T3N0-1M0 stages. The opposite character in mTOR, AMPK changes in the GCs before anti-cancer therapy is noted. At the same time, the local prevalence of the tumor and the lesion of regional lymph nodes were associated with a decrease in mTOR mRNA level.A decrease in mTOR expression is accompanied by an increase in AMPK expression in a gastric tumor. It is associated, first of all, with the clinical and morphological parameters of the primary process. mTOR expression is reduced in patients with a higher local prevalence of the process; in contrast, AMPK grows with tumor size.There is an increase in the LC3B expression, which, probably, can determine the response to therapy. As a result of the study, an increase in LC3B mRNA before the start of treatment and the concentration of autophagy protein after NACT with a decrease in therapy effectiveness was recorded. An increase in the protein level in patients with partial regression and stabilization of the tumor process by 3.65 and 5.78 times compared with patients with complete tumor regression was noted. Conclusion. The development of the disease and the prediction of anticancer therapy's effectiveness is directly related to the expression level of LC3B, mTOR, and AMPK. The following relationship was revealed: a decrease in mTOR expression and an increase in the level of mRNA and protein LC3B, AMPK expression combined with the progression of the disease in the form of the development of distant metastases, as well as the predicted future low effectiveness of NACT.