Phosphotidylinositol-3-kinase (PI3K) signaling is altered in the majority of human cancers. To gain insight into the roles of members of this pathway in growth regulation, we inactivated AKT1, AKT2, or PDPK1 genes by targeted homologous recombination in human colon cancer cell lines. Knockout of either AKT1 or AKT2 had minimum effects on cell growth or downstream signaling. In contrast, knockout of both AKT1 and AKT2 resulted in markedly reduced proliferation in vitro when growth factors were limiting and severely affected experimental metastasis in mice. Unexpectedly, AKT1 and AKT2 appeared to regulate growth through FOXO proteins, but not through either GSK3β or mTOR. In contrast, inactivation of PDPK1 affected GSK3β and mTOR activation. These findings show that the PI3K signaling pathway is wired differently in human cancer cells than in other cell types or organisms, which has important implications for the design and testing of drugs that target this pathway.

Correction for Genetic inactivation of AKT1, AKT2, and PDPK1 in human colorectal cancer cells clarifies their roles in tumor growth regulation

The genetic heritage for decades has been considered to respond only to gene promoters or suppressors, with specific roles for oncogenes or tumor-suppressor genes. Epigenetics is progressively attracting increasing interest because it has demonstrated the capacity of these regulatory processes to regulate the gene expression without modifying gene sequence. Several factors may influence epigenetics, such as lifestyles including food selection. A role for physical exercise is emerging in the epigenetic regulation of gene expression. In this review, we resume physiological and pathological implications of epigenetic modification induced by the physical activity (PA). Inflammation and cancer mechanisms, immune system, central nervous system, and the aging process receive benefits due to PA through epigenetic mechanisms. Thus, the modulation of epigenetic processes by physical exercise positively influences prevention, development, and the course of inflammatory and cancer diseases, as well as neurodegenerative illnesses. This growing field of studies gives rise to a new role for PA as an option in prevention strategies and to integrate pharmacological therapeutic treatments.

Role of physical exercise in the regulation of epigenetic mechanisms in inflammation, cancer, neurodegenerative diseases, and aging process.

Molecular assessment of colorectal cancer (CRC) is receiving growing attention, beyond RAS and BRAF, because of its influence on prognosis and prediction in cancer treatment. PTEN (phosphatase and tensin homologue), a tumor suppressor, regulating cell division and apoptosis, has been explored, and significant evidence suggests a role in cetuximab and panitumumab resistance linked to the epidermal growth factor receptor (EGFR) signal transduction pathway. Factors influencing PTEN activity should be analyzed to develop strategies to maximize the tumor suppressor role and to improve tumor response to cancer treatment. Therefore, an in-depth knowledge of the PI3K-Akt pathway-one of the major cancer survival pathways-and the role of PTEN-a major brake of this pathway-is essential in the era of precision medicine. The purpose of this literature review is to summarize the role of PTEN as a predictive factor and possible therapeutic target in CRC, focusing on ongoing studies and the possible implications in clinical practice.

https://www.mdpi.com/2072-6694/11/11/1765/pdf

PTEN in Colorectal Cancer: Shedding Light on Its Role as Predictor and Target.

BACKGROUND Most eukaryocytes release nano vesicles (30-120 nm), named exosomes, to various biological ﬂuids such as blood, lymph, and milk. Hepatocellular carcinoma (HCC) is one of the tumors with the highest incidence rate in primary malignant carcinoma of the liver. However, the mechanism of HCC proliferation remains elusive. In this study, we aim to explore whether HCC cell-derived exosomes affect the proliferation of cancer cells. MATERIAL AND METHODS Exosomes were isolated from HCC cells by ultracentrifugation and were visualized the phenotype by transmission electron microscopy. Cell proliferation was detected by Cell Counting Kit-8 assays and EdU (5-ethynyl-2-deoxyuridine) incorporation assays. Dual-luciferase assays were performed to validate the paired correlation of miR-155 and 3'-UTR of PTEN (gene of phosphate and tension homology deleted on chromosome 10). A xenograft mice model was constructed to verify the effect of exosome-mediated miR-155 on cell proliferation in vivo. RESULTS Our finding showed that miR-155 was enriched in exosomes released from HCC cells. The exosome-containing miR-155 transferred into new HCC targeted cells and lead to the elevation of HCC cells' proliferation. Besides, the exosomal miR-155 directly bound to 3'-UTR of PTEN leading to the reduction of relevant targets in recipient liver cells. The knockdown of PTEN attenuated the proliferation of HCC cells treated with the exosomal miR-155. Moreover, nude-mouse experiment results revealed a promotional effect of the exosomal miR-155 on HCC cell-acquired xenografts. CONCLUSIONS Our study indicated that exosomal-specific miR-155 transfers to adjacent and/or more distant cells and stimulates the proliferation of HCC cells.

Exosome-Mediated MiR-155 Transfer Contributes to Hepatocellular Carcinoma Cell Proliferation by Targeting PTEN.

Increasing reports demonstrated that dysregulated expression of microRNAs (miRNAs) leads to the progression of various tumors. Previous studies revealed that miR-328-3p exhibited dysregulated expression in various types of tumors. However, its function and underlying mechanism in osteosarcoma (OS) are still unexplored. The expression of miR-328-3p in the tissues and OS cell lines was detected by qRT-PCR analysis. The effects of miR-328-3p in the proliferation were analyzed by MTT assay. The proliferation and apoptosis of OS cells were examined by colony formation assay and TUNEL staining respectively. The migration and tumor formation ability of OS cells were measured by wound healing assay and xenograft in vivo mice assay. Furthermore, the regulatory roles of miR-328-3p/MMP16 were determined by western blot and luciferase reporter assay. The expression of miR-328-3p was significantly decreased in OS tissues and cell lines. Furthermore, overexpression of miR-328-3p inhibited the cell proliferation and migration, but promoted the apoptosis of OS cells in vitro. Moreover, the analysis in vivo showed that miR-328-3p effectively suppressed the formation of tumors. According to the results of western blot analysis and luciferase reporter assay, we identified matrix metalloproteinase-16 (MMP-16) acted as a direct target of miR-328-3p. Moreover, the expression level of MMP-16, which participates in the occurrence and development of many cancers, was negatively correlated with the miR-328-3p expression in OS cells. miR-328-3p inhibited the proliferation, migration but accelerated the apoptosis of OS by directly inhibiting MMP-16. And miR-328-3p/MMP-16 axis may be one of the mechanisms of OS development and a novel potential method for the treatment of OS in clinic.

/pdf/mir-328-3p-mediates-the-anti-tumor-effect-in-osteosarcoma-47kh624zqs.pdf

miR-328-3p mediates the anti-tumor effect in osteosarcoma via directly targeting MMP-16.

In recent decades, cancer has been one of the most important concerns of the human community, which affects human life from many different ways, such as breast, lung, colorectal, prostate, and other cancers. Colorectal cancer is one of the most commonly diagnosed cancers in the world that has recently been introduced as the third leading cause of cancer deaths in the world. microRNAs have a very crucial role in tumorgenesis and prevention of cancer, which plays a significant role with influencing various factors through different signaling pathways. Phosphoinositide 3 (PI3)-kinase/AKT is one of the most important signaling pathways involved in the control and growth of tumor in colorectal cancer, through important proteins of this pathway, such as PTEN and AKT, that they can perform specific influence on this process. Our effort in this study is to collect microRNAs that act as tumor suppressors and oncomirs in this cancer through PI3-kinase/AKT signaling pathway.

Mahsa Maleki Mogaddam

Papers

The role of microRNAs involved in PI3-kinase signaling pathway in colorectal cancer.