BackgroundMagnetic fluids containing superparamagnetic iron oxide nanoparticles represent an attractive platform as nanocarriers in chemotherapy. Recently, we developed a formulation of maghemite nanoparticles coated with rhodium (II) citrate, which resulted in in vitro cytotoxicity enhanced up to 4.6 times when compared to free rhodium (II) citrate formulation on breast carcinoma cells. In this work, we evaluate the antitumor activity and toxicity induced by these formulations in Balb/c mice bearing orthotopic 4T1 breast carcinoma.MethodsMice were evaluated with regard to the treatments’ toxicity through analyses of hemogram, serum levels of alanine aminotransferase, iron, and creatinine; DNA fragmentation and cell cycle of bone marrow cells; and liver, kidney and lung histology. In addition, the antitumor activity of rhodium (II) citrate and maghemite nanoparticles coated with rhodium (II) citrate was verified by tumor volume reduction, histology and immunohistochemistry.ResultsRegarding the treatments’ toxicity, no experimental groups had alterations in levels of serum ALT or creatinine, and this suggestion was corroborated by the histopathologic examination of liver and kidney of mice. Moreover, DNA fragmentation frequency of bone marrow cells was lower than 15% in all experimental groups. On the other hand, the complexes rhodium (II) citrate-functionalized maghemite and free rhodium (II) citrate led to a marked growth inhibition of tumor and decrease in CD31 and Ki-67 staining.ConclusionsIn summary, we demonstrated that both rhodium (II) citrate and maghemite nanoparticles coated with rhodium (II) citrate formulations exhibited antitumor effects against 4T1 metastatic breast cancer cell line following intratumoral administration. This antitumor effect was followed by inhibition of both cell proliferation and microvascularization and by tumor tissue injury characterized as necrosis and fibrosis. Remarkably, this is the first published report demonstrating the therapeutic efficacy of maghemite nanoparticles coated with rhodium (II) citrate. This treatment prolonged the survival period of treated mice without inducing apparent systemic toxicity, which strengthens its use for future breast cancer therapeutic applications.

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Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy worldwide. It has a history of great rates of success in treatment, but adults and infants still share a dismal prognosis. This condition makes the development of new prognostic markers linked to effective therapeutic strategies a matter of pressing concern. While cancer has traditionally been viewed as a genetic disease derived from alterations in oncogenes and tumor suppressors, it is well known nowadays that epigenetic changes also play a fundamental role in tumorigenesis. The SET family of lysine methyltransferases (KMT) has been implicated in a number of cancers, and SETD4 is a member that is still poorly characterized. In the present study we used qPCR to analyze the expression pattern of SETD4 among 83 pediatric ALL patients and non-neoplastic bone marrow (BM) samples and investigated the correlation between SETD4 transcription changes with the leukemic burden in ALL patients during chemotherapy. We found that SETD4 transcription levels are significantly upregulated in BM samples derived from ALL patients compared to non-neoplastic BM (8,5-fold higher, p < 0,001) and its expression correlated with leukemic burden. Importantly, levels of SETD4 decreased in patients that responded to chemotherapy treatment. We further investigated whether SETD4 transcription levels associates with that of SMYD2, another KMT previously identified as a prognostic marker in ALL. Transcription levels of SETD4 and SMYD2 were examined on day 15th and 29th of chemotherapy. Surprisingly, a high level of correlation (Spearman r = 0.925, p < 0.01) between both genes was observed in both treatment time points. Finally, survival outcomes were worst in ALL patients with high levels of SETD4 transcription (log-rank test, p < 0,05), evidencing its dysregulated expression is associated with an unfavorable disease prognosis. Together, these results point to SETD4 as a useful prognostic marker, a possible tool to assess response to therapy and an attractive target for drug development. Citation Format: Luis Augusto Muniz Telles, Luis Henrique Sakamoto, Alan Jhones Assis, Doralina de Amaral Rabello, Andrea Barretto Motoyama, Fabio Pittella-Silva. SETD4 transcription levels correlates with leukemic burden and SMYD2 transcription in acute lymphoblastic leukemia. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4758.