Genomic instability is an essential feature of cancer cells. The somatic mutation theory suggests that along with inherited ones, the changes in DNA caused by environmental factors may cause cancer. Although approximately 50–60 mutations per tumor are observed in established cancer tissue, it is known that not all of these mutations occur at the beginning of carcinogenesis but also occur later in the disease progression. The high frequency of somatic mutations referring to genomic instability contributes to the intratumoral genetic heterogeneity and treatment resistance. The contribution of the tumor microenvironment to the mutations observed following the acquirement of essential malignant characteristics of a cancer cell is one of the topics that have been extensively investigated in recent years. The frequency of mutations in hematologic tumors is generally less than solid tumors. Although it is a hematologic tumor, multiple myeloma is more similar to solid tumors in terms of the high number of chromosomal abnormalities and genetic heterogeneity. In multiple myeloma, bone marrow microenvironment also plays a role in genomic instability that occurs in the very early stages of the disease. In this review, we will briefly summarize the role of the tumor microenvironment and bone marrow microenvironment in the genomic instability seen in solid tumors and multiple myeloma.

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Adenoviral vectors (AV) are commonly used as vaccine and gene therapy vehicles because of their ease of construction, ability to grow to high titers in the large-scale production process, and safety for human applications. However, the efficiency rate of downstream processes for adenoviral vectors still varies greatly. In the current study, we aimed to investigate the effect of the downstream treatment protocol and microfiltration of the harvested upstream material on viral vector yield. We compared the performance of the repeated freeze–thaw (RFT) and the Tween-20 detergent lysis (DLT) methods. In addition, the effects of the cell lysis method, incubation temperature, and time on viral yield were investigated. The samples were incubated at either room temperature or 37 °C for 1-, 2-, and 4-h periods. Samples were filtered with PES and SFCA membrane. Virus yield and infectivity were assayed by qPCR and immuno-titration. In conclusion, our results suggest that 2-h incubation gives the best results when incubated at 37 °C for denarase activity when Tween-20 is used for virus recovery. If the room temperature is preferred, 4-h incubation could be preferred. A phase 1 clinical trial (NCT05526183, January 21, 2022) was started with the recombinant adenovirus used in the study.

e23014 Background: Angiogenesis is one of the key processes leading tumor progression and metastasis. Conventional chemotherapeutic drugs are usually cytotoxic to tumor cells at the therapeutic doses. The lowered doses of those drugs have been shown to induce apoptosis in endothelial cells and implemented as metronomic schedule in the clinic. We aimed to study the effects of very low doses of chemotherapeutic drugs on endothelial cell functions and gene and protein expression of pro-and anti-angiogenic factors. Methods: We first determined the IC50 doses of 5-fluorouracil, irinotecan, and oxaliplatin in a human umbilical endothelial cell line (HUVEC). Then we’ve tested the effects of the IC50, -1log, -2log and -3log of IC50 doses on endothelial cell migration and tube formation. We’ve also studied the effects of the assigned doses on expression levels of the genes VEGF-A, VEGFR2, PDGF-B, angiopoietin-2 (Ang-2), endothelin-1 (End-1), thrombospondin-1 (Tbs-1), iNOS, eNOS by real-time PCR, protein secretion levels of VEGF-A, PDGF-BB, Ang-2, End-1 and Tbs-1 by ELISA and nitrate/nitrite production by a colorimetric assay. Results: The IC50 dose levels of 5-FU, irinotecan, and oxaliplatin were 9,2 μM, 9,8 μM and 11,8 μM, respectively. We found that all the -1log, -2log and -3log of IC50 doses of the drugs tested in the study significantly decreased the migration capacity of the HUVEC cells. However, no significant changes were observed in tube formation of endothelial cells. Likewise, the expression levels of pro-angiogenic genes including Ang-2, iNOS, eNOS, PDGF-B and VEGF-A were significantly decreased at the same doses of the drugs. Accordingly, the levels of Tbs-1 were significantly increased at all 3 dose levels of the drugs. The most efficacious doses of the drugs to decrease NO levels in HUVEC cells were -1logIC50 for 5-FU, -2logIC50 for irinotecan and -3logIC50 for oxaliplatin. Conclusions: In conclusion, our results suggest that 5-FU, irinotecan, and oxaliplatin could decrease the pro-angiogenic and increase anti-angiogenic factor production in endothelial cells at the doses much lower than the usual metronomic schedules and warrant further research in animal models and clinical trials as an anti-angiogenic treatment modality.

e23013 Background: The efficacy of the metronomic use of conventional chemotherapeutic drugs in the clinic has been linked to their anti-angiogenic activity. However, the dose level for the metronomic use of the drugs with regard to anti-angiogenic activity is not known. In the current study, we aimed to study the effects of very low doses of 5-florouracil (5-FU), irinotecan and oxaliplatin on the synthesis of pro-angiogenic factors in tumor cells. Methods: We first determined the IC50 doses of 5-FU, irinotecan, and oxaliplatin in human tumor cell lines (HT-29: colon cancer cells, MCF-7: breast cancer cells and LNCaP: prostatic carcinoma cells). Then we applied the drugs to the assigned cells at the dose levels of IC50, -1log, -2log and -3log of IC50. The effects of the drugs on both gene expression and protein secretion levels of pro-angiogenic genes including vascular endothelial growth factor A (VEGF-A), basic-fibroblast growth factor (bFGF), matrix metalloproteinase-9 (MMP-9), platelet-derived growth factor-beta (PDGF-B), interleukin-8 (IL-8) and factor secretion by real-time PCR and sandwich ELISA. Results: The IC50 levels of 5-FU, irinotecan, and oxaliplatin in tumor cells were found as shown in the Table. We found that -1logIC50 dose level of 5-FU efficiently suppressed the pro-angiogenic genes both at the gene expression and protein secretion levels. However, the -2logIC50 and -3logIC50 dose levels of both irinotecan and oxaliplatin significantly inhibited gene expression and protein secretion. Conclusions: In conclusion, our results suggest that irinotecan and oxaliplatin could be used as anti-angiogenic agents at the very low doses. The -1logIC50 dose for 5-FU and the -2log and -3logIC50 doses of irinotecan and oxaliplatin could be further tested in animal models and clinical trials. Table. The IC50 dose levels of the drugs in tumor cell lines. [Table: see text]