Eliminating oncogenic RAS: back to the future at the drawing board.

RAS drug development has made enormous strides in the past ten years, with the first direct KRAS inhibitor being approved in 2021. However, despite the clinical success of covalent KRAS-G12C inhibitors, we are immediately confronted with resistances as commonly found with targeted drugs. Previously believed to be undruggable due to its lack of obvious druggable pockets, a couple of new approaches to hit this much feared oncogene have now been carved out. We here concisely review these approaches to directly target four druggable sites of RAS from various angles. Our analysis focuses on the lessons learnt during the development of allele-specific covalent and non-covalent RAS inhibitors, the potential of macromolecular binders to facilitate the discovery and validation of targetable sites on RAS and finally an outlook on a future that may engage more small molecule binders to become drugs. We foresee that the latter could happen mainly in two ways: First, non-covalent small molecule inhibitors may be derived from the development of covalent binders. Second, reversible small molecule binders could be utilized for novel targeting modalities, such as degraders of RAS. Provided that degraders eliminate RAS by recruiting differentially expressed E3-ligases, this approach could enable unprecedented tissue- or developmental stage-specific destruction of RAS with potential advantages for on-target toxicity. We conclude that novel creative ideas continue to be important to exterminate RAS in cancer and other RAS pathway-driven diseases, such as RASopathies.

Dietary intake of genistein suppresses hepatocellular carcinoma through AMPK-mediated apoptosis and anti-inflammation.

BACKGROUND: Women have a lower risk of hepatocellular carcinoma (HCC) than men, and the decreased possibility of HCC in women is thought to depend on estrogen levels. As a soybean-isoflavone product, genistein has estrogenic activity in various reproductive tissues, because it mimics 17ß-estradiol and binds the estrogen receptor. Though genistein is a known liver cancer suppressor, its effects have not been studies in long-term experiment, where genistein is fed to a female animal model of HCC. METHODS: Mice were treated with diethylnitrosamine (DEN) to induce HCC at 2 weeks of age and fed with supplemental genistein for 5 months, from 40 to 62 weeks of age. RESULTS: The dietary intake of genistein decreased the incidence of HCC and suppressed HCC development. Genistein induced phospho-AMPK in total liver extracts, Hep3B cells, and Raw 264.7 cells, and phospho-AMPK promoted apoptosis in liver and Hep3B cells. Moreover, phospho-AMPK down-regulated pro-inflammatory responses and ameliorated liver damage. A suppressed pro-inflammatory response with increased mitochondrial respiration was concomitantly observed after genistein treatment. CONCLUSIONS: Genistein-mediated AMPK activation increases hepatocyte apoptosis through energy-dependent caspase pathways, suppresses the inflammatory response in resident liver macrophages by increased cellular respiration, and consequently inhibits the initiation and progression of HCC.

An Improved PDE6D Inhibitor Combines with Sildenafil To Inhibit KRAS Mutant Cancer Cell Growth.

The trafficking chaperone PDE6D (or PDEδ) was proposed as a surrogate target for K-Ras, leading to the development of a series of inhibitors that block its prenyl binding pocket. These inhibitors suffered from low solubility and suspected off-target effects, preventing their clinical development. Here, we developed a highly soluble, low nanomolar PDE6D inhibitor (PDE6Di), Deltaflexin3, which has the lowest off-target activity as compared to three prominent reference compounds. Deltaflexin3 reduces Ras signaling and selectively decreases the growth of KRAS mutant and PDE6D-dependent cancer cells. We further show that PKG2-mediated phosphorylation of Ser181 lowers K-Ras binding to PDE6D. Thus, Deltaflexin3 combines with the approved PKG2 activator Sildenafil to more potently inhibit PDE6D/K-Ras binding, cancer cell proliferation, and microtumor growth. As observed previously, inhibition of Ras trafficking, signaling, and cancer cell proliferation remained overall modest. Our results suggest reevaluating PDE6D as a K-Ras surrogate target in cancer.

Percutaneous revision of dysfunctional shunts in patients who underwent intrahepatic portosystemic shunt procedure via percutaneous or conventional method: 11-years single center experience.

BACKGROUND AND AIM: Our primary objective is to report the results of the ultrasound (US)-guided revision technique of transhepatic shunt in patients in whom intrahepatic portosystemic shunt was created by the percutaneous or conventional route. Our secondary objective is to investigate whether there is an association between the indication for a portosystemic shunt and the need for post-shunt revision. METHODS: Data from 117 consecutive patients who had a transjugular intrahepatic portosystemic shunt placed percutaneously or conventionally were extracted from hospital electronic medical records and examined those who underwent revision within 11 years and those who did not. US-guided transhepatic shunt revision technique was evaluated in terms of technical success, complications, and patency. In addition, the relationship between etiology and the need for revision was also examined using the chi-square test in three groups. RESULTS: Forty six point two percent of patients who underwent transjugular intrahepatic portosystemic shunt required one or more revisions within 11 years. While patency of the shunt could be established via the transjugular route in 83.3% of revision patients, it was necessary to use the transhepatic route in 16.7%. The technical success rate for the US-guided transhepatic shunt revision method was 100%, and the pressure gradient between the portal and hepatic venous systems decreased below 10 mmHg in all patients at the end of the procedure. CONCLUSION: US-guided transhepatic shunt revision is a safe and effective method where transjugular revision cannot be performed. In addition, the revision rate is significantly higher in patients who have undergone transjugular intrahepatic portosystemic shunt due to Budd-Chiari syndrome compared with other groups.

Traditional Medicine (Mahuang-Tang) Improves Ovarian Dysfunction and the Regulation of Steroidogenic Genes in Letrozole-Induced PCOS Rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Mahuang-Tang (MHT) has traditionally been used in Asia to treat a variety of diseases, such as fever without sweating, joint pain, lower back pain, asthma, and gynecological conditions. Polycystic ovary syndrome (PCOS) is a kind of gynecological disease that causes amenorrhea, infertility, and menopausal and urogenital disorders that could benefit from MHT treatment. AIM OF THE STUDY: In this study, we examined the effects of MHT on ovarian hormones and steroidogenic enzymes in female PCOS rats. METHODS AND RESULTS: The PCOS rat model was induced by Letrozole, and an in vivo evaluation of whether the dietary consumption of MHT improved the PCOS-like symptoms was conducted. The luteinizing hormone (LH) level and luteinizing hormone/follicular-stimulating hormone (LH/FSH) ratio increased in PCOS rats but decreased following MHT treatment. In the PCOS rats, the reduced estrogen level was restored to that of normal controls with MHT treatment in serum. The transcription level(s) of gonadotropin receptors (Fshr and Lhr), steroid receptors (Pgr, and Esr1) and steroidogenic enzymes (Cyp19a1, Hsd3b1, Hsd17a1, and Cyp11a1) changed under the PCOS condition, and were regulated by MHT treatment in the ovaries of PCOS rats. The reproductive tissues of Letrozole-induced PCOS rats were restored into estrogenic condition from androgen environments. CONCLUSION: These results suggest that MHT ameliorates the symptoms of PCOS by improving the dysregulation of ovarian steroids and steroidogenic enzymes in PCOS rats.

Curcumae Radix Extract Decreases Mammary Tumor-Derived Lung Metastasis via Suppression of C-C Chemokine Receptor Type 7 Expression.

Curcumae radix is the dry root of Curcuma longa L. (turmeric) that can be used either as a spice or traditional medicine. The aim of this study was to investigate the survival benefits and the anti-metastatic activity of curcumae radix extract (CRE) in MCF7 cells and in MMTV-PyMT transgenic mice-a mouse model of breast cancer metastasis. In vitro wound scratch assay revealed that CRE treatment inhibited cell motility and cell migration in a dose-dependent manner. To investigate the effect of CRE in breast cancer metastasis, MMTV-PyMT transgenic female virgin mice were used and randomly divided into two groups. For survival curve analysis, CRE was administered in a dose of 50 mg/kg to 8⁻20-week-old mice. Interestingly, CRE treatment significantly increased the median and prolonged survival of MMTV-PyMT mice. Furthermore, CRE treatment decreased tumor burden and inhibited cell proliferation in primary breast tumor, and also suppressed mammary tumor-derived lung metastasis. The size of the lung metastases substantially decreased in the CRE-treated group compared with the ones in the control group. Curcumae radix extract showed anti-metastatic activity through regulating the expression of metastasis markers including C-C Chemokine Receptor Type 7, Matrix Metalloproteinase 9 and the proto-oncogenes c-fos and c-jun. We demonstrated that these metastatic regulators were decreased when CCR7 expression was suppressed in MCF7 cells transfected with CCR7 siRNA. The results of this study show that curcumae radix exerts antitumor and anti-metastatic activities, and we suggest that curcumae radix might be a potential supplement for the treatment and prevention of breast cancer metastasis.

Loss of progesterone receptor membrane component 1 promotes hepatic steatosis via the induced de novo lipogenesis.

Non-alcoholic fatty liver disease (NAFLD) results from triglyceride accumulation within the liver and some of them advances to non-alcoholic steatohepatitis (NASH). It is important to note that in NAFLD development, hepatic de novo lipogenesis (DNL) derives from excess carbohydrates and fats under a condition of excess energy through ß-oxidation. As a main regulator for DNL, sterol regulatory element-binding protein 1 (Srebp-1) forms complex with progesterone receptor membrane component 1 (Pgrmc1). To investigate whether Pgrmc1 may have a notable effect on DNL via SREBP-1 activation, we generated Pgrmc1 knockout (KO) mice and fed a high fat diet for one month. High-fat-fed Pgrmc1 KO mice showed a substantial increase in levels of hepatic TG accumulation, and they were predisposed to NAFLD when compared to WT mice. Loss of Pgrmc1 increased mature SREBP-1 protein level, suggesting that induction of hepatic steatosis in Pgrmc1 KO mice might be triggered by de novo lipogenesis. Moreover, Pgrmc1 KO mice were also more vulnerable to early stage of NASH, showing high levels of alanine aminotransferase, obesity-linked pro-inflammatory cytokines, and fibrosis markers. This is interesting because Pgrmc1 involves with the first step in regulating the hepatic de novo lipogenesis under an excess energy condition.

Upregulation of multi drug resistance genes in doxorubicin resistant human acute myelogeneous leukemia cells and reversal of the resistance.

The major problem in the treatment of acute myeloid leukemia (AML) patients results from multidrug resistance to administered anticancer agents. Drug resistance proteins, MDR1 and MRP1, which work as drug efflux pumps, can mediate the multidrug resistance of human leukemia cells. In this study, the mechanisms of resistance to doxorubicin-induced cell death in human HL60 AML cells were examined. Continuous exposure of cells to step-wise increasing concentrations of doxorubicin resulted in the selection of HL60/DOX cells, which expressed about 10.7-fold resistance as compared to parental sensitive cells. The expression analyses of MRP1 and MDR1 drug efflux proteins in doxorubicin-sensitive and -resistant HL60 cells revealed that there was an upregulation of MRP1 gene in HL60/DOX cells as compared to parental sensitive cells. On the other hand, while there was no expression of MDR1 gene in parental cells, the expression of MDR1 gene was upregulated in HL60/DOX cells. HL60/DOX cells also showed cross-resistance to cytosine arabinoside (Ara-c). This resistance was reversed by a combination therapy of Ara-c and cyclosporine A. However, the expression levels of CD15 and CD16 surface markers were significantly decreased in HL60/DOX cells.

Identification of polymorphisms on the MDR1 gene among Turkish population and their effects on multidrug resistance in acute leukemia patients.

Multidrug-resistance (MDR) phenotype is a serious limitation to the effective chemotherapeutic treatment of many cancer types, including leukemia. One of the most important proteins, the over-expression of which is responsible for the multidrug-resistance phenotype in many cancer types, is P-glycoprotein. This protein is the product of the MDR1 gene. In previous studies, single-nucleotide polymorphisms (SNPs) C3435T, G2677T, and T-129C in the MDR1 gene were shown to be correlated with lower P-glycoprotein expression in normal tissues. It was suggested that this might have an advantage in cancer chemotherapy by resulting in a low drug-resistance phenotype. The frequencies of these SNPs were studied in 45 acute leukemia patients (25 of which were primary refractory and 20 of which were drug-sensitive) and 17 healthy individuals, forming a Turkish population of 62 individuals. In the first part of the study, these polymorphisms were compared with other populations. Marked differences were apparent between African and Turkish populations for the C3435T polymorphism. On the other hand, similarities were found between other Caucasian/Asian and Turkish populations (P < 0.001). However, for the G2677T polymorphism, the Turkish population is different than Japanese and German populations (P < 0.001). For the T-129C polymorphism, all individuals in the studied population were homozygous for the T/T genotype. In the second part of this study, drug-resistant and drug-sensitive acute leukemia patients were compared for these SNPs. These polymorphisms did not seem to have a significant effect on P-glycoprotein-mediated drug resistance in the patients studied.