Nationwide Real-World Data of Microsatellite Instability and/or Mismatch Repair Deficiency in Cancer: Prevalence and Testing Patterns.

Determination of microsatellite instability (MSI)/mismatch repair (MMR) status in cancer has several clinical implications. Our aim was to integrate MSI/MMR status from patients tested in Greece to assess the prevalence of MSI-high (MSI-H)/deficient MMR (dMMR) per tumor type, testing patterns over time and concordance between MSI and MMR status. We retrospectively recorded MSI/MMR testing data of patients with diverse tumor types performed in pathology and molecular diagnostics laboratories across Greece. Overall, 18 of 22 pathology and/or molecular diagnostics laboratories accepted our invitation to participate. In the 18 laboratories located across the country, 7916 tumor samples were evaluated for MSI/MMR status. MSI/MMR testing significantly increased in patients with colorectal cancer (CRC) and other tumor types overtime (p < 0.05). The highest prevalence was reported in endometrial cancer (47 of 225 patients, 20.9%). MSI-H/dMMR was observed in most tumor types, even in low proportions. Among 904 tumors assessed both for MSI and MMR status, 21 had discordant results (overall discordance rate, 2.3%). We reported MSI-H/dMMR prevalence rates in patients with diverse cancers, while demonstrating increasing referral patterns from medical oncologists in the country overtime. The anticipated high rate of concordance between MSI and MMR status in paired analysis was confirmed.

Design, synthesis, and biological evaluation of new raloxifene analogues of improved antagonist activity and endometrial safety.

Raloxifene agonism of estrogen receptor (ER) in post-menopausal endometrium is not negligible. Based on a rational drug design workflow, we synthesized 14 analogues of raloxifene bearing a polar group in the aromatic ring of the basic side chain (BSC) and/or changes in the bulkiness of the BSC amino group. Analogues with a polar BSC aromatic ring and amino group substituents of increasing volume displayed increasing ER antagonism in Ishikawa cells. Analogues with cyclohexylaminoethoxy (13a) or adamantylaminoethoxy BSC (13b) lacking a polar aromatic ring displayed high ER-binding affinity and ER antagonism in Ishikawa cells higher than raloxifene and similar to fulvestrant (ICI182,780). The endometrial surface epithelium of immature female CD1 mice injected with 13b was comparable to that of vehicle-treated mice, while that of mice treated with estradiol, raloxifene or 13b in combination with estradiol was hyperplastic. These findings indicate that raloxifene analogues with a bulky BSC amino group could provide for higher endometrial safety treatment of the menopausal syndrome.

Can the response to a platinum-based therapy be predicted by the DNA repair status in non-small cell lung cancer?

Preclinical evidence has been accumulating on the impact of the DNA repair status on the sensitivity/resistance to anticancer agents in different tumor types, including lung cancer. The possibility to predict the response to therapy, and specifically to platinum agents, based on tumor specific DNA repair functionality would enable to tailor its use only in those patients with maximum chances to respond, avoiding the burden of toxicity in those ones with lesser chances. We here reviewed the clinical evidence on the prognostic role of DNA repair markers and/or functional assays in predicting the response to a platinum-based chemotherapy in lung cancer patients. Consequently, we focused on those proteins involved in pathways repairing platinum induced DNA inter-strand and intra-strand crosslinks. Most promising clinical trials targeting the nucleotide repair protein ERCC1 in non-small cell lung cancer later on suffered from serious drawbacks. Nevertheless, these results spurred a variety of preclinical studies on a multitude of alternative DNA repair markers. However so far, no one of the analyzed DNA repair markers can be considered a reliable and mature biomarker for selecting patients. We discuss the reasons for such failure which discloses novel strategies for the future.

Induction of the paraoxonase-1 gene expression by resveratrol.

OBJECTIVE: The human paraoxonase-1 (PON-1) is a high-density lipoprotein-associated enzyme, mainly secreted by the liver, that displays protective properties toward cardiovascular disease and organophosphate intoxication. Resveratrol is a polyphenolic phytoalexin found in grapes and wine and is thought to display cardioprotective effects. It is able to interact with transcriptional modulators such as the estrogen receptor alpha (ERalpha). We investigated the effect of resveratrol on the PON-1 gene expression. METHODS AND RESULTS: PON-1 activity assays, Northern blot, and transfection experiments showed that resveratrol increased the PON-1 gene expression in human hepatocyte primary cultures and in the HuH7 hepatoma cell line involving a transcriptional mechanism. The resveratrol effect was not ERalpha-dependent and was surprisingly mediated by the aryl hydrocarbon receptor (AhR) and an unconventional AhR responsive element in the PON-1 gene promoter. This agonist effect of resveratrol was specific for this DNA motif and was not observed on classical AhR responsive elements. CONCLUSIONS: These observations suggest that the PON-1 gene induction may be involved in the cardioprotective properties of resveratrol. They also highlight a ligand-dependent differential modulation of AhR-sensitive genes.

Dietary polyphenols increase paraoxonase 1 gene expression by an aryl hydrocarbon receptor-dependent mechanism.

Human paraoxonase 1 (PON-1) is a serum high-density lipoprotein-associated enzyme mainly secreted by the liver. It has endogenous and exogenous substrates and displays protective properties with respect to cardiovascular disease and organophosphate intoxication. In the HuH7 human hepatoma cell line, PON-1 activity and mRNA levels were increased by dietary polyphenolic compounds such as quercetin but also by toxic ligands of the aryl hydrocarbon receptor (AhR) such as 3-methylcholanthrene (3-MC). However, the 2,3,7,8-tetrachlorobenzo(p)dioxin (TCDD) was a poor inducer. Transient and stable transfection assays indicated that these compounds increased the PON-1 gene promoter activity in an AhR-dependent manner, since their effect was inhibited by 7-keto-cholesterol and AhR-directed short interfering RNA. Deletions and mutations studies showed that a xenobiotic responsive element (XRE)-like sequence within the PON-1 promoter mediated the effect of 3-MC and quercetin. In contrast with consensus XREs from the cytochrome P450 1A1 gene, the PON-1 XRE-like element mediated preferentially the effect of quercetin compared to the results seen with TCDD. Furthermore, AhR binding to this element was preferentially activated by quercetin. These observations provide a molecular mechanism for the regulation of the cardioprotective enzyme PON-1 by polyphenols. They suggest also that AhR ligands may differentially regulate gene expression depending on the DNA target sequence.

Opposite regulation of the human paraoxonase-1 gene PON-1 by fenofibrate and statins.

The human paraoxonase-1 (PON-1) is a serum high-density lipoprotein-associated phosphotriesterase secreted mainly by the liver. This enzyme is able to hydrolyze toxic organophosphate xenobiotics, endogenous oxidized phospholipids, and homocysteine thiolactone. Physiologically, it is thought to protect against cardiovascular diseases. The level of PON-1 gene expression is a major determinant of paraoxonase-1 status but little is known regarding the regulation of this gene. We identified several transcription start sites and characterized the regulation of its promoter by fibrates and statins. In HuH7 human hepatoma cells, the PON-1 secreted enzymatic activity and mRNA levels were increased by fenofibric acid (approximately 70%) and decreased by several statins (approximately 50%). Transient and stable transfection assays in HuH7 cells indicated that the modulation of the mRNA and enzymatic activity levels could be accounted for by the regulation of the PON-1 gene promoter activity by these drugs. These effects are probably not mediated by the PPAR alpha because over-expression of this receptor decreased the fibrate effect and did not modify statins activity. The repressive effect of statins is reversed by mevalonate and 22(R)-hydroxycholesterol, suggesting the involvement of the liver X receptor in the mechanism. The opposite effects of fenofibrate and statins could be consistent with clinical data on homocysteine levels after hypolipidemic drug treatment. Regarding the toxicological aspects, the induction achieved with fenofibric acid, although limited, could increase organophosphate metabolism and may be relevant in certain conditions for protective treatments.