The C-Terminal Acidic Tail Modulates the Anticancer Properties of HMGB1

Energy metabolism reprogramming was recently listed as a hallmark of cancer. In this process, the switch from pyruvate kinase isoenzyme type M1 to pyruvate kinase isoenzyme type M2 (PKM2) is believed to play a crucial role. Interestingly, the activity of the active form of PKM2 can efficiently be inhibited by the high-mobility group box 1 (HMGB1) protein, leading to a rapid blockage of glucose-dependent aerobic respiration and cancer cell death. HMGB1 is a member of the HMG protein family. It contains two DNA-binding HMG-box domains and an acidic C-terminal tail capable of positively or negatively modulating its biological properties. In this work, we report that the deletion of the C-terminal tail of HMGB1 increases its activity towards a large panel of cancer cells without affecting the viability of normal immortalized fibroblasts. Moreover, in silico analysis suggests that the truncated form of HMGB1 retains the capacity of the full-length protein to interact with PKM2. However, based on the capacity of the cells to circumvent oxidative phosphorylation inhibition, we were able to identify either a cytotoxic or cytostatic effect of the proteins. Together, our study provides new insights in the characterization of the anticancer activity of HMGB1.

Expression Pattern of Purinergic Signaling Components in Colorectal Cancer Cells and Differential Cellular Outcomes Induced by Extracellular ATP and Adenosine

The purine nucleotide adenosine triphosphate (ATP) is known for its fundamental role in cellular bioenergetics. However, in the last decades, different works have described emerging functions for ATP, such as that of a danger signaling molecule acting in the extracellular space on both tumor and stromal compartments. Beside its role in immune cell signaling, several studies have shown that high concentrations of extracellular ATP can directly or indirectly act on cancer cells. Accordingly, it has been reported that purinergic receptors are widely expressed in tumor cells. However, their expression pattern is often associated with contradictory cellular outcomes. In this work, we first investigated gene expression profiles through "RNA-Sequencing" (RNA Seq) technology in four colorectal cancer (CRC) cell lines (HT29, LS513, LS174T, HCT116). Our results demonstrate that CRC cells mostly express the A2B, P2X4, P2Y1, P2Y2 and P2Y11 purinergic receptors. Among these, the P2Y1 and P2Y2 coding genes are markedly overexpressed in all CRC cells compared to the HCEC-1CT normal-like colonic cells. We then explored the cellular outcomes induced by extracellular ATP and adenosine. Our results show that in terms of cell death induction extracellular ATP is consistently more active than adenosine against CRC, while neither compound affected normal-like colonic cell survival. Intriguingly, while for the P2Y2 receptor pharmacological inhibition completely abolished the rise in cytoplasmic Ca²⁺ observed after ATP exposure in all CRC cell lines, Ca²⁺ mobilization only impacted the cellular outcome for HT29. In contrast, non-selective phosphodiesterase inhibition completely abolished the effects of extracellular ATP on CRC cells, suggesting that cAMP and/or cGMP levels might determine cellular outcome. Altogether, our study provides novel insights into the characterization of purinergic signaling in CRC.

Colorectal Cancer and Immunity: From the Wet Lab to Individuals

Simple Summary

Tackling the current dilemma of colorectal cancer resistance to immunotherapy is puzzling and requires novel therapeutic strategies to emerge. However, characterizing the intricate interactions between cancer and immune cells remains difficult because of the complexity and heterogeneity of both compartments. Developing rationales is intellectually feasible but testing them can be experimentally challenging and requires the development of innovative procedures and protocols. In this review, we delineated useful in vitro and in vivo models used for research in the field of immunotherapy that are or could be applied to colorectal cancer management and lead to major breakthroughs in the coming years.

Abstract

Immunotherapy is a very promising field of research and application for treating cancers, in particular for those that are resistant to chemotherapeutics. Immunotherapy aims at enhancing immune cell activation to increase tumor cells recognition and killing. However, some specific cancer types, such as colorectal cancer (CRC), are less responsive than others to the current immunotherapies. Intrinsic resistance can be mediated by the development of an immuno-suppressive environment in CRC. The mutational status of cancer cells also plays a role in this process. CRC can indeed be distinguished in two main subtypes. Microsatellite instable (MSI) tumors show a hyper-mutable phenotype caused by the deficiency of the DNA mismatch repair machinery (MMR) while microsatellite stable (MSS) tumors show a comparatively more “stable” mutational phenotype. Several studies demonstrated that MSI CRC generally display good prognoses for patients and immunotherapy is considered as a therapeutic option for this type of tumors. On the contrary, MSS metastatic CRC usually presents a worse prognosis and is not responsive to immunotherapy. According to this, developing new and innovative models for studying CRC response towards immune targeted therapies has become essential in the last years. Herein, we review the in vitro and in vivo models used for research in the field of immunotherapy applied to colorectal cancer.

Pheromone hydrolysis by cuticular and interior esterases of the antennae, legs, and wings of the cabbage looper moth,Trichoplusia ni (Hübner)

Examination was made of the hydrolytic activities of esterases obtained from the antennae, legs, and wings of 3-day-old cabbage looper moths,Trichoplusia ni (Hübner), by elution and by homogenation of those appendages. Pheromone hydrolysis in 1-min assays was monitored by use of tritium-labeled (Z)-7-dodecen-1-ol acetate and thin-layer chromatography to separate the reaction products. Listed according to the activities of the esterases obtained by homogenation, the organs were antennae > legs > wings. In contrast, the order according to the activities of the eluted esterases was wings > legs > antennae. Also, the eluted enzymes were less active than the esterases obtained by homogenization. The relatively high pheromone-hydrolyzing activity present in homogenized antennae suggests that the esterases originated inside the antennae and lends support to the hypothesis proposed in earlier investigations that pheromone-inactivating enzymes may play an important role in the olfactory process, possibly by clearing pheromone from the vicinity of the olfactory receptors. The esterases detected on the cuticle, on the other hand, may function by preventing surface accumulation of pheromone. The higher measured esterase activity in homogenates of prothoracic legs than of mesothoracic or metathoracic legs suggests that the prothoracic legs, which are used to clean the antennae of debris, may function by removing and degrading pheromone from the surface of antennae.

Embryonic development of an endoparasitoid, Microplitis croceipes (Hymenoptera: Braconidae) in cell line-conditioned media

Embryos of the parasitoid Microplitis croceipes develop from pregerm band stage to first larval instar in cell culture medium conditioned by a cell line (IPLB-LdFB) derived from fat body from an atypical host Lymantria dispar. However, the percentage of eggs that develop normally to the first larval instar stage is significantly less than for those maintained in IPL-52B medium conditioned with host fat body tissue. Therefore, we examined the capacity of five insect cell lines to promote growth and development of pregerm band eggs in five media, IPL-52B, TC-199, TC-100, Grace's, and ExCell 400. The developmental response of M. croceipes was dependent both on the cell line and the cell culture medium used. TC-100, TC-199, and Grace's media promoted development to the germ band stage without the need for conditioning with host tissue. IPL-52B supported development to the germ band stage when a defined lipid concentrate was added. In IPL-52B medium, the IPLB-LdFB cell line promoted a significantly higher number of eggs developing to germ band relative to the other cell lines; however, none of the cell line-conditioned IPL-52B medium significantly stimulated egg hatch relative to the control medium. None of the cell line-conditioned Grace's media had a significant effect on eggs attaining germ band stage compared with the Grace's control medium. However, Grace's medium conditioned with the IAL-TND1 and IPLB-LdFB cell lines promoted development beyond germ band, resulting in a significantly higher percentage of hatching eggs than the Grace's control medium.(ABSTRACT TRUNCATED AT 250 WORDS)