The development of novel therapies that are selective for cancer cells, with limited toxicity to normal tissues, has been a challenge for oncology researchers. Genetically modified Salmonella typhimurium, which is capable of multiplying selectively in tumours and inhibiting their growth, represents a new approach for cancer treatment. Because of its selectivity for tumour tissues, S. typhimurium would also be an ideal vector for delivering therapeutic proteins to tumours. VNP20009, an attenuated strain of S. typhimurium with deletions in msbB and purI genes, possesses desirable attributes, such as low toxicity, tumour-selective multiplication and an intrinsic tumouricidal activity, making it particularly promising. VNP20009 accumulates preferentially in tumours of mice bearing B16F10 melanoma and M019 lung carcinoma. This preferential accumulation also occurs in animals implanted sc. with human tumour xenografts Lox, C8186, DLD1, SW620, HCT116, HTB177, DU145, MDA-MB-231 and Caki. VNP20009 proliferates and accumulates to levels between 1 x 108 and 2 x 109 colony-forming units (cfu)/g tumour after 4 - 5 days, following a single iv. injection of VNP20009 at 1 x 106 cfu/mouse. The amount of VNP20009 accumulating in liver is between 3 x 104 and 2 x 106 cfu/g. VNP20009 also inhibits the growth of a wide spectrum of murine transplantable tumours and human tumour xenografts and is currently undergoing Phase I clinical trials in cancer patients.
ABSTRACT The l -nucleoside analog β- l -2′,3′-dideoxy-2′,3′-didehydro-5-fluorocytidine (β- l -Fd4C) was first shown to exhibit potent activity against hepatitis B virus (HBV) in tissue culture and then to significantly inhibit viral spread during acute infection in the duck HBV model (F. Le Guerhier et al., Antimicrob. Agents Chemother. 44:111–122, 2000). We have therefore examined its antiviral activity in a mammalian model of chronic HBV infection, the woodchuck chronically infected with woodchuck hepatitis virus (WHV). Side-by-side comparison of β- l -Fd4C and lamivudine administered intraperitoneally during short-term and long-term protocols demonstrated a more profound inhibition of viremia in β- l -Fd4C-treated groups. Moreover, β- l -Fd4C induced a marked inhibition of intrahepatic viral DNA synthesis compared with that induced by lamivudine. Nevertheless, covalently closed circular (CCC) DNA persistence explained the lack of clearance of infected hepatocytes expressing viral antigens and the relapse of WHV replication after drug withdrawal. Liver histology showed a decrease in the inflammatory activity of chronic hepatitis in woodchucks receiving β- l -Fd4C. An electron microscopy study showed the absence of ultrastructural changes of hepatic mitochondria, biliary canaliculi, and bile ducts. However, a loss of weight was observed in all animals, whatever the treatment, as was a transient skin pigmentation in all woodchucks during β- l -Fd4C treatment. There was no evidence that lamivudine or β- l -Fd4C could prevent the development of hepatocellular carcinoma with the protocols used. These results indicate that β- l -Fd4C exhibits a more potent antiviral effect than lamivudine in the WHV model but was not able to eradicate CCC DNA and infected cells from the liver at the dosage and with the protocol used.
Patients diagnosed with localized high-risk prostate cancer have higher rates of recurrence, and the introduction of neoadjuvant intensive hormonal therapies seeks to treat occult micrometastatic disease by their addition to definitive treatment. Sufficient profiling of baseline disease has remained a challenge in enabling the in-depth assessment of phenotypes associated with exceptional vs. poor pathologic responses after treatment. In this study, we report comprehensive and integrative gene expression profiling of 37 locally advanced prostate tumors prior to six months of androgen deprivation therapy (ADT) plus the androgen receptor (AR) inhibitor enzalutamide prior to radical prostatectomy. A robust transcriptional program associated with HER2 activity was positively associated with poor outcome and opposed AR activity, even after adjusting for common genomic alterations in prostate cancer including
Abstract The human squamous cell carcinoma SqC/Y1 undergoes spontaneous terminal differentiation in the confluent state. The degree of maturation was markedly increased by glucocorticoids and by both human recombinant and placental lipocortin I. Western analyses demonstrated cellular secretion of lipocortin into the medium. Glucocorticoid‐induced maturation was antagonized by a lipocortin l‐specific monoclonal antibody, by phospholipase A 2 (PLA2), and by arachidonic acid. Induction of the differentiation of SqCC/Y1 cells by lipocortin I was prevented by arachidonic acid. The PLA2 inhibitor, dibromoacetophenone, caused an increase in envelope‐competent cells indicating that inhibition of PLA2 results in induction of differentiation. Epidermal growth factor prevented the induction of differentiation by both lipocortin I and by glucocorticoids. The nonsteroidal lipoxygenase/cyclo‐oxygenase inhibitor, phenidone, also increased SqCC/Y1 differentiation, suggesting that leukotrienes, thromboxanes, and/or prostaglandins may be involved in lipocortin‐mediated regulation of SqCC/Y1 maturation. The findings support a role for lipocortin I in mediating the effects of glucocorticoids on epidermal cell differentiation.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Laromustine (VNP40101M; 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)-2-(methylamino) carbonylhydrazine) is a novel sulfonylhydrazine alkylating agent. For the first time In vitro profiling and mass balance of [14C] VNP40101M in rat, dog, monkey and human liver microsomes was investigated. Also, the role of human cytochrome P450 (CYP) and flavin-containing monooxygenase (FMO) enzymes in the conversion of [14C] VNP40101M by NADPH-fortified human liver microsomes was determined. In this study, [14C]-VNP40101M was converted to five radioactive components (C-1, C-2, C-3, C-4 and C-7) after 60 min of incubation with dog, monkey and human liver microsomes. With the exception of C-3, the same components were detected with rat liver microsomes. In the presence of NADPH, after 60 min of incubation, the loss of substrate for rat, dog, monkey and human was 63, 82, 76 and 64%, respectively and mass balance ranged from 91.0 – 99.3%. In the absence of NADPH, after 60 min of incubation with [14C] VNP40101M (100 µM), the loss of substrate for rat, dog, monkey and human liver microsomes was 59, 53, 61 and 59%, respectively and mass balance ranged from 100.6 – 116.4%. The profiles of metabolites were similar. The relative abundance of individual metabolites was not species dependent. The formation of C-7 was not observed in zero cofactor (no NADPH) or zero-protein samples, suggesting that its formation was enzymatic. The formation of C-1, C-2, C-3, and C-4 increased with respect to incubation time. Using a panel of CYP enzymes including rCYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6 and 3A4, it was shown that C-7 formation was catalyzed by CYP2B6 and CYP3A4/5. The results of this study suggest that (1) P450 plays a role in C-7 formation but plays little or no role in the conversion of [14C] VNP40101M to C-1 through C-4, and (2) the relative abundance of individual degradation/metabolite products were not species dependent. These findings provide a comprehensive understanding of the metabolism of this new agent.
Laromustine (VNP40101M; 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)-2-(methylamino) carbonylhydrazine) is a novel sulfonylhydrazine alkylating agent. Phase 1 metabolism of laromustine was reported recently and showed that laromustine undergoes rearrangement, dehalogenation, and hydrolysis at physiological pH to form active moieties. (1) A mechanism for the rearrangement was proposed on the basis of fragmentation ions. (1) (,) (2) In this article, we report the phase II conjugates of VNP40101M and VNP4090CE which were formed after incubation of VNP40101M or VNP4090CE with pooled human liver microsomes (HLM) and cofactors nicotinamide adenine dinucleotide phosphate (NADPH), glutathione (GSH), N-acetylecysteine (NAC), and cysteine (CYS). Eight novel phase II conjugates (M-1 to M-8) were identified and characterized by hydrogen-deuterium exchange (H-D), stable isotope ((13)C-labeled VNP40101M), and MS(n) experiments. M-4 and M-5 were further confirmed by nuclear magnetic resonance spectroscopy (NMR). The short-lived CH(3)SO(2)CH(2)CH(2)-, methylformamide and CH(3)SO(2)NHN═CHCH(2)- moieties were generated from VNP40101M. The reactive intermediates CH(3)SO(2)CH(2)CH(2)- and methylformamide formed conjugates with GSH, CYS, and NAC. The CH(3)SO(2)NHN═CHCH(2)- moiety formed conjugates with GSH and NAC. M-2, M-4, and M-6 were only detected from the incubation of VNP40101M because VNP4090CE does not contain a methylformamide group. All other conjugates were formed by both VNP40101M and VNP4090CE. The in vitro studies found that VNP40101M and VNP4090CE undergo activation in human liver microsomes. The results from this study showed that laromustine produces several reactive intermediates that may play a role in the toxicities seen in the clinical trials.
The work reported in this article has evaluated the relative molecular activity of the 5'-triphosphate of a novel beta-L-nucleoside with an unsaturated ribose residue, beta-L-2', 3'-dideoxy-2',3'-didehydro-5-fluorocytidine (beta-L-Fd4CTP), with that of beta-L-2',3'-dideoxy-5-fluorocytidine (beta-L-FddCTP) and 2', 3'-dideoxycytidine (ddCTP), on DNA strand elongation by human immunodeficiency virus-1 reverse transcriptase (HIV RT) and human DNA polymerases alpha (pol alpha), beta (pol beta), gamma (pol gamma), and epsilon (pol epsilon). The concentrations of beta-L-Fd4CTP that inhibited the yield of products by 50% were 0.20 micro M, 1.8 micro M, and 4.0 micro M for HIV RT, pol gamma, and pol beta, respectively. The beta-L-Fd4CTP at a concentration as high as 40 micro M had no inhibitory effect on pol epsilon, but could inhibit pol alpha by 10-20% at 20 micro M. The Km and relative Vmax values of beta-L-Fd4CTP, beta-L-FddCTP, and ddCTP for incorporation into the standing start point of 5'-[32P]-oligonucleotide primer annealed with M13mp19 phage DNA by HIV RT and human DNA polymerases were evaluated. The efficiency of incorporation (Vmax/Km) of beta-L-Fd4CTP by HIV RT was about 4-fold and 12-fold higher than that of ddCTP and beta-L-FddCTP, respectively. In contrast, the Vmax/Km ratio of beta-L-Fd4CTP for pol gamma was 7-fold lower than that of ddCTP, but 4-fold higher than that of beta-L-FddCTP. Pol alpha could use beta-L-Fd4CTP as a substrate, but only at a high concentration (>20 micro M). Incorporation of beta-L-Fd4CTP by pol epsilon could not be detected. A hypothesis about the preferable recognition of the 2',3'-dideoxy-2',3'-didehydro- structure of beta-L-Fd4CTP to that of the 2',3'-dideoxy-structure of beta-L-FddCTP by HIV RT is discussed.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Abstract Background: Intense neoadjuvant androgen deprivation therapy (inADT) is an emerging treatment paradigm for localized high-risk prostate cancer, but in certain patients a subset of tumors will recur after surgery. In tumors with endogenously low androgen receptor (AR) activity, expression of the EGFR family protein HER2 was enriched. We sought to investigate the role of HER2 in driving the proliferation of prostate cancer under androgen-depleted environments. We hypothesized that overexpression of HER2 would decrease AR activity, while its knockdown would conversely increase AR expression beyond baseline levels. Methods: The AR-expressing 22Rv1 and LNCaP prostate cancer cell lines were cultured and plated for transfection. HER2 overexpression was achieved using an exogenous HER2 (ERBB2) plasmid, while HER2 knockdown was performed using siRNA, alongside controls for both groups. Cell lysates were collected at 24-, 48-, and 72-hour time points. Western blotting was performed to examine HER2, AR, PSA, and actin expression. Results: Western blot analysis confirmed successful overexpression and knockdown of HER2, using an exogenous HER2 plasmid and siRNA, respectively. In 22Rv1 and LNCaP cells overexpressing HER2, AR (and AR-V7 in 22Rv1 cells) levels were decreased compared to the control cells. Conversely, 22Rv1 and LNCaP cells with knockdown of HER2 exhibited elevated AR expression. Biological replicates to confirm these findings are in progress. Additional studies will also examine the impact of HER2 signaling and activity on downstream pro-proliferative pathways. Conclusions: Manipulation of HER2 expression highlights a potential role of EGFR family proteins as a mechanism for prostate cancer growth in androgen-deprived environments. Future studies will validate this finding at the RNA level using qPCR and probe downstream targets of HER2 using western blotting. These preliminary findings have implications for the treatment of advanced tumors for which inADT is not a viable option. Targeting HER2 and its downstream signaling pathways represent an intriguing mechanism to overcome resistance to androgen deprivation therapy in newly-diagnosed, treatment-naïve patients. Citation Format: Daniel K.Y. Low, Scott Wilkinson, Isaiah M. King, Shana Y. Trostel, Adam G. Sowalsky. Modulation of HER2 as a mechanism for AR expression [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr A007.
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