Stable formation of mutated p53 multimers in a Chinese hamster cell line causes defective p53 nuclear localization and abrogates its residual function

Amplifying Curcumin's Antitumor Potential: A Heat-Driven Approach for Colorectal Cancer Treatment

Introduction

Peritoneal metastases from colorectal cancer (CRC) present a significant clinical challenge with poor prognosis, often unresponsive to systemic chemotherapy. Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is a treatment approach for select patients. The use of curcumin, a natural compound with antitumor properties, in HIPEC is of interest due to its lower side effects compared to conventional drugs and potential for increased efficacy through direct delivery to the peritoneal cavity.

Methods

An in vitro hyperthermic model was developed to simulate clinical HIPEC conditions. Three colon cancer cell lines (SK-CO-1, COLO205, SNU-C1) representing different genetic mutations (p53, KRAS, BRAF) were treated with either curcumin (25 µM) or mitomycin-C (1 µM) for 1, 2, or 3 hours. Post-treatment, cells were incubated at 37°C (normothermia) or 42°C (hyperthermia). Cell viability and proliferation were assessed at 24, 48 and 72 hours post-treatment using Annexin V/PI, MTT assay, trypan blue exclusion, and Hoffman microscopy.

Results

Hyperthermia significantly enhanced the antitumor efficacy of curcumin, evidenced by a two-fold reduction in cell viability compared to normothermia across all cell lines. In the SNU-C1 cell line, which harbors a p53 mutation, mitomycin-C failed to significantly impact cell viability, unlike curcumin, suggesting mutation-specific differences in treatment response.

Discussion

The findings indicate that hyperthermia augments the antitumor effects of curcumin in vitro, supporting the hypothesis that curcumin could be a more effective HIPEC agent than traditional drugs like mitomycin-C. Mutation-associated differences in response to treatments were observed, particularly in p53 mutant cells. While further studies are needed, these preliminary results suggest that curcumin in HIPEC could represent a novel therapeutic strategy for CRC patients with peritoneal metastases. This approach may offer improved outcomes with fewer side effects, particularly in genetically distinct CRC subtypes.

Mechanisms and biological importance of photon-induced bystander responses: do they have an impact on low-dose radiation responses

Elucidating the biological effect of low linear energy transfer (LET), low-dose and/or low-dose-rate ionizing radiation is essential in ensuring radiation safety. Over the past two decades, non-targeted effects, which are not only a direct consequence of radiation-induced initial lesions produced in cellular DNA but also of intra- and inter-cellular communications involving both targeted and non-targeted cells, have been reported and are currently defining a new paradigm in radiation biology. These effects include radiation-induced adaptive response, low-dose hypersensitivity, genomic instability, and radiation-induced bystander response (RIBR). RIBR is generally defined as a cellular response that is induced in non-irradiated cells that receive bystander signals from directly irradiated cells. RIBR could thus play an important biological role in low-dose irradiation conditions. However, this suggestion was mainly based on findings obtained using high-LET charged-particle radiations. The human population (especially the Japanese, who are exposed to lower doses of radon than the world average) is more frequently exposed to low-LET photons (X-rays or γ-rays) than to high-LET charged-particle radiation on a daily basis. There are currently a growing number of reports describing a distinguishing feature between photon-induced bystander response and high-LET RIBR. In particular, photon-induced bystander response is strongly influenced by irradiation dose, the irradiated region of the targeted cells, and p53 status. The present review focuses on the photon-induced bystander response, and discusses its impact on the low-dose radiation effect.

Chemoprevention of rat hepatocarcinogenesis with histone deacetylase inhibitors: efficacy of tributyrin, a butyric acid prodrug

Hepatocellular carcinoma (HCC) ranks in prevalence and mortality among top 10 cancers worldwide. Butyric acid (BA), a member of histone deacetylase inhibitors (HDACi) has been proposed as an anticarcinogenic agent. However, its short half-life is a therapeutical limitation. This problem could be circumvented with tributyrin (TB), a proposed BA prodrug. To investigate TB effectiveness for chemoprevention, rats were treated with the compound during initial phases of "resistant hepatocyte" model of hepatocarcinogenesis, and cellular and molecular parameters were evaluated. TB inhibited (p < 0.05) development of hepatic preneoplastic lesions (PNL) including persistent ones considered HCC progression sites. TB increased (p < 0.05) PNL remodeling, a process whereby they tend to disappear. TB did not inhibit cell proliferation in PNL, but induced (p < 0.05) apoptosis in remodeling ones. Compared to controls, rats treated with TB presented increased (p < 0.05) hepatic levels of BA indicating its effectiveness as a prodrug. Molecular mechanisms of TB-induced hepatocarcinogenesis chemoprevention were investigated. TB increased (p < 0.05) hepatic nuclear histone H3K9 hyperacetylation specifically in PNL and p21 protein expression, which could be associated with inhibitory HDAC effects. Moreover, it reduced (p < 0.05) the frequency of persistent PNL with aberrant cytoplasmic p53 accumulation, an alteration associated with increased malignancy. Original data observed in our study support the effectiveness of TB as a prodrug of BA and as an HDACi in hepatocarcinogenesis chemoprevention. Besides histone acetylation and p21 restored expression, molecular mechanisms involved with TB anticarcinogenic actions could also be related to modulation of p53 pathways.