Novel mRNA isoforms and mutations of uridine monophosphate synthetase and 5-fluorouracil resistance in colorectal cancer.

The drug fluorouracil (5-FU) is a widely used antimetabolite chemotherapy in the treatment of colorectal cancer. The gene uridine monophosphate synthetase (UMPS) is thought to be primarily responsible for conversion of 5-FU to active anticancer metabolites in tumor cells. Mutation or aberrant expression of UMPS may contribute to 5-FU resistance during treatment. We undertook a characterization of UMPS mRNA isoform expression and sequence variation in 5-FU-resistant cell lines and drug-naive or -exposed primary and metastatic tumors. We observed reciprocal differential expression of two UMPS isoforms in a colorectal cancer cell line with acquired 5-FU resistance relative to the 5-FU-sensitive cell line from which it was derived. A novel isoform arising as a consequence of exon skipping was increased in abundance in resistant cells. The underlying mechanism responsible for this shift in isoform expression was determined to be a heterozygous splice site mutation acquired in the resistant cell line. We developed sequencing and expression assays to specifically detect alternative UMPS isoforms and used these to determine that UMPS was recurrently disrupted by mutations and aberrant splicing in additional 5-FU-resistant colorectal cancer cell lines and colorectal tumors. The observed mutations, aberrant splicing and downregulation of UMPS represent novel mechanisms for acquired 5-FU resistance in colorectal cancer.

BCL2 mutations in diffuse large B-cell lymphoma.

BCL2 is deregulated in diffuse large B-cell lymphoma (DLBCL) by the t(14;18) translocation, gene amplification and/or nuclear factor-κB signaling. RNA-seq data have recently shown that BCL2 is the most highly mutated gene in germinal center B-cell (GCB) DLBCL. We have sequenced BCL2 in 298 primary DLBCL biopsies, 131 additional non-Hodgkin lymphoma biopsies, 24 DLBCL cell lines and 51 germline DNAs. We found frequent BCL2 mutations in follicular lymphoma (FL) and GCB DLBCL, but low levels of BCL2 mutations in activated B-cell DLBCL, mantle cell lymphoma, small lymphocytic leukemia and peripheral T-cell lymphoma. We found no BCL2 mutations in GC centroblasts. Many mutations were non-synonymous; they were preferentially located in the flexible loop domain, with few in BCL2-homology domains. An elevated transition/transversions ratio supports that the mutations result from somatic hypermutation. BCL2 translocations correlate with, and are likely important in acquisition of, additional BCL2 mutations in GCB DLBCL and FL. DLBCL mutations were not independently associated with survival. Although previous studies of BCL2 mutations in FL have reported mutations to result in pseudo-negative BCL2 protein expression, we find this rare in de-novo DLBCL.

2,4-Diamino-6-(bis-2-chloroethyl)aminomethyl pteridine. A new potent anticancer drug.

2,4-Diamino-6-(bis-2-chloroethyl)aminomethyl pteridine has been synthesized and found to be highly potent against L-1210 mouse leukemia lymphoblasts. A single dose of 5 mg/kg injected 24 h after the tumor inoculation increased the life-span of 50% of mice to more than 200%, while the other 50% of animals were cured.

Structure-activity relationships for hallucinogenic N,N-dialkyltryptamines: photoelectron spectra and serotonin receptor affinities of methylthio and methylenedioxy derivatives.

Serotonin receptor affinity and photelectron spectral data were obtained on a number of substituted N,N-dimethyltryptamines. Evidence is presented that electron-donating substituents in the 5-position lead to enhanced behavioral disruption activity and serotonin receptor affinity as compared to unsubstituted N,N-dimethyltryptamine and analogues substituted in the 4- or 6-position. Some correlation was found between ionization potentials and behavioral activity, which may have implications concerning the mechanism of receptor binding.

Behavioral and serotonin receptor properties of 4-substituted derivatives of the hallucinogen 1-(2,5-dimethoxyphenyl)-2-aminopropane.

The serotonin (5-HT) receptor affinities and behavioral (discriminative stimulus) properties of a series of 4-substituted derivatives of 1-(2,5-dimethoxyphenyl)-2-aminopropanes (2,5-DMA) were investigated. The substituents at the 4-position included H, OMe, OEt, Me, Et, F, Br, I, and NO2. Substituent lipophilicities (pi values) of these functionalities appear to have a minimal effect on either 5-HT receptor affinity or behavioral activity. Those derivatives previously found to be most potent in human studies possess significant affinity for 5-HT receptors. Furthermore, when rats trained to discriminate (+/-)-1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM) from saline were used, generalization was found to occur upon administration of the 4-substituted 2,5-DMA derivatives. Because a direct relationship exists between the ED50 values obtained from these discrimination studies and human hallucinogenic potencies, the discriminative stimulus paradigm, with DOM as a training drug, appears to be a useful tool for comparing the quantitative and qualitative (DOM-like) effects produced by certain hallucinogenic agents.

Structure-activity relationships in potentially hallucinogenic N,N-dialkyltryptamines substituted in the benzene moiety.

A series of N,N-dialkyltryptamines with methylthio or methylenedioxy substituents in the 4, 5, and 6 positions and methyl or isopropyl on the side-chain nitrogen has been synthesized. The behavioral pharmacology of these compounds showed them to possess Bovet-Gatti profiles characteristic of hallucinogens, and the 5-methylthio congener was the most potent. Binding studies at [3H]LSD and [3H]5-HT sites demonstrated that no single structural feature correlated with binding or behavioral changes and suggest a complex mode of action for these potential hallucinogenic agents.

Hallucinogens as discriminative stimuli: a comparison of 4-OMe DMT and 5-OMe DMT with their methythio counterparts.

Rats, trained to discriminate 1.5 mg/kg of the hallucinogenic agent 5-methoxy-N,N-dimethyltryptamine (5-OMe DMT) from saline in a two-lever drug discrimination task, were challenged with various doses of the 4-methoxy, 4-methylthio and 5-methylthio derivatives of DMT. The 5-OMe DMT cue was found to generalize to all three of these agents; the order of potency is 5-OMe greater than 5-SMe greater than 4-OMe greater than 4-SMe DMT.

Hallucinogenic N-methylated indolealkylamines in the cerebrospinal fluid of psychiatric and control populations.

The incidence and quantities of dimethyltryptamine and O-methylbufotenine were studied in the cerebrospinal fluid of patients suffering acute schizophrenic illnesses and in surgical and neurological control groups. Some schizophrenic patients have higher levels of both amines than do controls, though the differences in distribution did not reach statistical significance in the sample studied. The gas-chromatographic technique used is sensitive at the low picogram level.

Stereospecific actions of 2,5-dimethoxy-4-methylamphetamine (DOM) on colonic temperature in the rat at various ambient temperatures.

The R(-) and S(+)-isomers of 2,5-dimethoxy-4-methylamphetamine (DOM) produce a dose-dependent hypothermia in rats kept in the cold (6 degrees C). 2 This hypothermia was linearly dependent upon ambient temperature and the R(-)-isomer was considerably more potent than the S(+)-isomer. 3 A statistically significant tachyphylaxis was observed when R(-)-DOM was administered on two successive days. The response seven days after the second injection was similar to that on the first day of injection. 4 The hypothermia induced by R(-) and S(+)-DOM was antagonized by methysergide but not by p-chlorophenylalanine (PCPA) or pimozide. Methysergide, PCPA or pimozide alone did not elicit hypothermia at the doses used. The results indicate that R(-) and S(+)-DOM act at post-synaptic 5-hydroxytryptamine receptors.

Antagonism of d-lysergic acid diethylamide and mescaline by 1-methyl-1, 2, 5, 6-tetrahydropyridine-N, N-diethyl-carboxamide (THPC).

Contractions of sheep umbilical vasculature induced by 5-hydroxytryptamine, mescaline and d-lysergic acid diethylamide (LSD) were antagonized by 1-methyl-1, 2, 5, 6-tetrahydropyridine-N, N-diethyl-carboxamide (THPC) 5 X 10(-4)M. THPC did not block contractile responses to angiotensin. The data are interpreted to support our previous suggestions that certain chemical entities representing portions of the LSD molecule may be effectively studied as antagonists to the hallucinogens. The present data indicate that THPC is a weak 5-hydroxytryptamine receptor antagonist.