Differential translation of mRNA isoforms underlies oncogenic activation of cell cycle kinase Aurora A

Investigating the role of let-7a microRNA in cisplatin sensitivity of A549 lung cancer cells

Lung cancer (LC) is a major cause of death worldwide, and cisplatin is commonly used as a chemotherapeutic drug for the treatment of LC. However, high doses of cisplatin can reduce its efficacy, leading to the need for new methods to increase LC cell sensitivity to this drug molecule. To overcome this problem, it is important to discover new methods to increase the sensitivity of LC cells to cisplatin. In this study, we investigated the use of anti-let-7a, a microRNA, to enhance the cisplatin sensitivity in A549 LC cells by comparing its effects with the commonly used oncogenes akt1 and pik3ca. The A549 cell line was transfected with anti-let-7a, and its effects were analyzed using functional assays. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay was used for the measurement of cell viability, and gene expression levels of cell death-associated genes, were analyzed by using quantitative real-time PCR (qRT-PCR). Results showed that anti-let-7a downregulation decreased the viability of A549 cells significantly compared to the control group in the presence of cisplatin. Moreover, the single treatment of cells with anti-let-7a and cisplatin resulted in significant changes in gene expression levels, with the increased expression of pro-apoptotic genes and decreased expression of anti-apoptotic genes. Moreover, anti-let-7a treatment was found to increase the response of A549 cells to cisplatin by reducing the expression of oncogenes akt1 and pik3ca. This study suggests that anti-let-7a treatment may enhance the A549 LC cell sensitivity to cisplatin by modulating the expression of akt1 and pik3ca genes, making it a promising therapeutic target for LC treatment.

Cleavage and polyadenylation machinery as a novel targetable vulnerability for human cancer

The role of alternative polyadenylation of mRNA in sustaining aggressive features of tumors is quite well established, as it is responsible for the 3'UTR shortening of oncogenes and subsequent relief from miRNA-mediated repression observed in cancer cells. However, the information regarding the vulnerability of cancer cells to the inhibition of cleavage and polyadenylation (CPA) machinery is very scattered. Only few recent reports show the antitumor activity of pharmacological inhibitors of CPSF3, one among CPA factors. More in general, the fact that deregulated CPA can be seen as a new hallmark of cancer and as a potential reservoir of novel therapeutic targets has never been formalized. Here, to extend our view on the potential of CPA inhibition (CPAi) approaches as anticancer therapies, we systematically tested the fitness of about one thousand cell lines of different cancer types upon depletion of all known CPA factors by interrogating genome-scale CRISPR and RNAi dependency maps of the DepMap project. Our analysis confirmed core and accessory CPA factors as novel vulnerabilities for human cancer, thus highlighting the potential of CPAi as anticancer therapy. Among all, CPSF1 appeared as a promising actionable candidate for drug development, as it showed low dependency scores pancancer and particularly in highly proliferating cells. In a personalized medicine perspective, the observed differential vulnerability of cancer cell lines to selected CPA factors may be used to build up signatures to predict response of individual human tumors to CPAi approaches.

Translational adaptation in breast cancer metastasis and emerging therapeutic opportunities

Breast cancer's tendency to metastasize poses a critical barrier to effective treatment, making it a leading cause of mortality among women worldwide. A growing body of evidence is showing that translational adaptation is emerging as a key mechanism enabling cancer cells to thrive in the dynamic tumor microenvironment (TME). Here, we systematically summarize how breast cancer cells utilize translational adaptation to drive metastasis, highlighting the intricate regulation by specific translation machinery and mRNA attributes such as sequences and structures, along with the involvement of tRNAs and other trans-acting RNAs. We provide an overview of the latest findings and emerging concepts in this area, discussing their potential implications for therapeutic strategies in breast cancer.

Mutual communication between radiosensitive and radioresistant esophageal cancer cells modulates their radiosensitivity

Radiotherapy is an important treatment modality for patients with esophageal cancer; however, the response to radiation varies among different tumor subpopulations due to tumor heterogeneity. Cancer cells that survive radiotherapy (i.e., radioresistant) may proliferate, ultimately resulting in cancer relapse. However, the interaction between radiosensitive and radioresistant cancer cells remains to be elucidated. In this study, we found that the mutual communication between radiosensitive and radioresistant esophageal cancer cells modulated their radiosensitivity. Radiosensitive cells secreted more exosomal let-7a and less interleukin-6 (IL-6) than radioresistant cells. Exosomal let-7a secreted by radiosensitive cells increased the radiosensitivity of radioresistant cells, whereas IL-6 secreted by radioresistant cells decreased the radiosensitivity of radiosensitive cells. Although the serum levels of let-7a and IL-6 before radiotherapy did not vary significantly between patients with radioresistant and radiosensitive diseases, radiotherapy induced a more pronounced decrease in serum let-7a levels and a greater increase in serum IL-6 levels in patients with radioresistant cancer compared to those with radiosensitive cancer. The percentage decrease in serum let-7a and the percentage increase in serum IL-6 levels at the early stage of radiotherapy were inversely associated with tumor regression after radiotherapy. Our findings suggest that early changes in serum let-7a and IL-6 levels may be used as a biomarker to predict the response to radiotherapy in patients with esophageal cancer and provide new insights into subsequent treatments.