Adjuvant treatment of colon cancer with microsatellite instability - the state of the art

The epigenetic modifier HDAC2 and the checkpoint kinase ATM determine the responses of microsatellite instable colorectal cancer cells to 5-fluorouracil

The epigenetic modifier histone deacetylase-2 (HDAC2) is frequently dysregulated in colon cancer cells. Microsatellite instability (MSI), an unfaithful replication of DNA at nucleotide repeats, occurs in about 15% of human colon tumors. MSI promotes a genetic frameshift and consequently a loss of HDAC2 in up to 43% of these tumors. We show that long-term and short-term cultures of colorectal cancers with MSI contain subpopulations of cells lacking HDAC2. These can be isolated as single cell-derived, proliferating populations. Xenografted patient-derived colon cancer tissues with MSI also show variable patterns of HDAC2 expression in mice. HDAC2-positive and HDAC2-negative RKO cells respond similarly to pharmacological inhibitors of the class I HDACs HDAC1/HDAC2/HDAC3. In contrast to this similarity, HDAC2-negative and HDAC2-positive RKO cells undergo differential cell cycle arrest and apoptosis induction in response to the frequently used chemotherapeutic 5-fluorouracil, which becomes incorporated into and damages RNA and DNA. 5-fluorouracil causes an enrichment of HDAC2-negative RKO cells in vitro and in a subset of primary colorectal tumors in mice. 5-fluorouracil induces the phosphorylation of KAP1, a target of the checkpoint kinase ataxia-telangiectasia mutated (ATM), stronger in HDAC2-negative cells than in their HDAC2-positive counterparts. Pharmacological inhibition of ATM sensitizes RKO cells to cytotoxic effects of 5-fluorouracil. These findings demonstrate that HDAC2 and ATM modulate the responses of colorectal cancer cells towards 5-FU.

Circulating Vitamin D Level and Its Impact on Mortality and Recurrence in Stage III Colorectal Cancer Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Vitamin D (VD) has been implicated in several diseases, including colorectal cancer (CRC). This study aimed to determine whether there is an association between VD levels and time-to-outcome in stage III CRC patients through a systematic review and meta-analysis.

METHODS

The study adhered to the PRISMA 2020 statement. Articles were searched in PubMed/MEDLINE and Scopus/ELSEVIER. Four articles were selected, with the primary objective of providing a pooled estimate of the risk of death specifically in stage III CRC patients based on pre-operative VD levels. Study heterogeneity and publication bias were analyzed using Tau² statistics and funnel plots.

RESULTS

The selected studies showed significant heterogeneity regarding time-to-outcome, technical assessments, and serum VD concentration measures. The pooled analysis of 2628 and 2024 patients revealed a 38% and 13% increase in the risk of death (HR: 1.38, 95% CI: 0.71-2.71) and recurrence (HR: 1.13; 95% CI: 0.84-1.53), respectively, for random-effects models among patients with lower levels of VD.

CONCLUSIONS

Our findings suggest that a low concentration of VD has a significant negative impact on time-to-outcome in stage III CRC.

Recent Advancements, Limitations, and Future Perspectives of the use of Personalized Medicine in Treatment of Colon Cancer

Due to the heterogeneity of colon cancer, surgery, chemotherapy, and radiation are ineffective in all cases. The genomic profile and biomarkers associated with the process are considered in personalized medicine, along with the patient's personal history. It is based on the response of the targeted therapies to specific genetic variations. The patient's genetic transcriptomic and epigenetic features are evaluated, and the best therapeutic approach and diagnostic testing are identified through personalized medicine. This review aims to summarize all the necessary, updated information on colon cancer related to personalized medicine. Personalized medicine is gaining prominence as generalized treatments are finding it challenging to contain colon cancer cases which currently rank fourth among global cancer incidence while being the fifth largest in total death cases worldwide. In personalized therapy, patients are grouped into specific categories, and the best therapeutic approach is chosen based on evaluating their molecular features. Various personalized strategies are currently being explored in the treatment of colon cancer involving immunotherapy, phytochemicals, and other biomarker-specific targeted therapies. However, significant challenges must be overcome to integrate personalized medicine into healthcare systems completely. We look at the various signaling pathways and genetic and epigenetic alterations associated with colon cancer to understand and identify biomarkers useful in targeted therapy. The current personalized therapies available in colon cancer treatment and the strategies being explored to improve the existing methods are discussed. This review highlights the advantages and limitations of personalized medicine in colon cancer therapy. The current scenario of personalized medicine in developed countries and the challenges faced in middle- and low-income countries are also summarized. Finally, we discuss the future perspectives of personalized medicine in colon cancer and how it could be integrated into the healthcare systems.