On the significance of an alternate pathway of melatonin synthesis via 5-methoxytryptamine: comparisons across species.

Melatonin is a phylogenetically ancient molecule. It is ubiquitously present in almost all organisms from primitive photosynthetic bacteria to humans. Its original primary function is presumable to be that of an antioxidant with other functions of this molecule having been acquired during evolution. The synthetic pathway of melatonin in vertebrates has been extensively studied. It is common knowledge that serotonin is acetylated to form N-acetylserotonin by arylalkylamine N-acetyltransferase (AANAT) or arylamine N-acetyltransferase (SNAT or NAT) and N-acetylserotonin is, subsequently, methylated to melatonin by N-acetylserotonin O-methyltransferase (ASMT; also known as hydroxyindole-O-methyltransferase, HIOMT). This is referred to as a classic melatonin synthetic pathway. Based on new evidence, we feel that this classic melatonin pathway is not generally the prevailing route of melatonin production. An alternate pathway is known to exist, in which serotonin is first O-methylated to 5-methoxytryptamine (5-MT) and, thereafter, 5-MT is N-acetylated to melatonin. Here, we hypothesize that the alternate melatonin synthetic pathway may be more important in certain organisms and under certain conditions. Evidence strongly supports that this alternate pathway prevails in some plants, bacteria, and, perhaps, yeast and may also occur in animals.

Metastatic colorectal micropapillary carcinoma presenting as lymphangitic lung carcinomatosis.

Pulmonary lymphangitic carcinomatosis denotes the infiltration of tumor cells into the lung parenchymal lymphatic channels. Breast, lung, stomach, and colon adenocarcinoma are the most common origin of this invasion pattern. The micropapillary variant of colorectal adenocarcinoma has a high rate of lymph node metastases and poor overall survival. A 49 year-old man with a 6 months history of persistent cough and a relevant occupational chemical exposure had a computed tomography that showed bilateral interstitial lung infiltrates. The lung biopsy demonstrated a micropapillary adenocarcinoma with diffusely obstruction of the lung parenchymal lymphatics. The immunohistochemistry confirmed a colorectal origin. The colonoscopy evidenced a mass with identical morphology. Colorectal micropapillary carcinoma with metastatic lung lymphangitic carcinomatosis can occur, as a persistent cough, as presenting symptom in extraordinarily rare cases. To the best of our knowledge, this is the first case of an alive patient with colorectal metastatic micropapillary carcinoma presenting with lymphangitic lung carcinomatosis.

Immunotyping of tumor-infiltrating lymphocytes in triple-negative breast cancer and genetic characterization.

Tumor-infiltrating lymphocytes (TILs) reflect the host immune response against cancer cells. Immunomodulators have been recently suggested as a novel therapeutic strategy against triple-negative breast cancer (TNBC). However, the TIL profile in TNBC has not been thoroughly investigated. In the present study, the percentage, immunophenotype and genetic profiles of TILs in pre-surgical tumor samples of patients with TNBC were evaluated prior to neoadjuvant chemotherapy (NAC). Patients diagnosed with breast cancer at Hospital San José TecSalud were consecutively and prospectively enrolled in the present study between August 2011 and August 2015. The pathological response to NAC was evaluated using the de Miller-Payne and MD Anderson Cancer Center system. TIL percentage (low, intermediate, and high) was evaluated using special hematoxylin-eosin staining on the core needle biopsies. The immunophenotype of TILs was assessed by immunohistochemistry (IHC) for CD3+, CD4+ and CD8+. In addition, the gene expression profile of CD3, CD4, CD8, CD20, CD45, forkhead box P3, interleukin 6, programmed cell death 1 and CD274 molecule was assessed in all patients. A total of 26 samples from patients with TNBC prior to NAC were included in the present study. TILs were low in 30.7%, intermediate in 38.4% and elevated in 30.7% of tumors. CD3+ and CD4+ counts were associated with the pathological response to NAC (P=0.04). Finally, an overexpression pattern of CD3, CD4, CD8, CD45 and CD20 genes was observed in patients with a partial or complete pathological response. The present results demonstrated that TILs may predict the pathological response to NAC in patients with TNBC. Furthermore, a more accurate association was identified between the high expression levels of CD3, CD4, CD8, CD45 and CD20 genes and partial and complete pathological response, compared with the association between high expression and IHC alone.

Pre-treatment with melatonin decreases abamectin induced toxicity in a nocturnal insect Spodoptera litura (Lepidoptera: Noctuidae).

AIM: Oxidative stress is an important component of the mechanism of pesticide toxicity. The aim of the present study was to investigate the time-dependent melatonin effects against abamectin-induced oxidative stress in a S.litura model. Larvae were divided into 5 different groups; (1) control group,(2) Melatonin group (4.3×10-5M/100ml diet), (3) Abamectin group 1.5ml/L, (4) Pre-melatonin treated group (PM) (4.3×10-5M/100ml diet) before abamectin exposure 1.5ml/L, (5) Post-melatonin treated group (TM) after abamectin exposure. Melatonin was supplemented via artificial diet in PM and TM animals during 24h. MAIN METHODS: Midgut, fatbody, and hemolymph, were collected for the analysis of oxidative stress markers (Total ROS, GSH, nitrite, TBARS, LPO), antioxidant enzyme levels (SOD, GST, CAT, POX, APOX) in fifth instar larvae. Midgut damage was examined by using morphological analysis. KEY FINDINGS: Our results observed that ABA group showed significant changes (p<0.001) in the ROS and carbonyl content in midgut. The increase of antioxidant enzyme levels (SOD, CAT, POX, and APOX) in midgut was led by the continuous free radical scavenger cascade of melatonin. Significant (p<0.01) increases in CAT and APOX levels were seen in the fatbody of PM and TM treated insects. SIGNIFICANCE: In conclusion, the results of the study revealed that abamectin toxicity generates oxidative stress in the insect, while pre-melatonin treatment reduces this damage due to its antioxidant properties, especially POX levels in midgut, fatbody, and hemolymph. Therefore, indoleamine can play a vital role curtailing the abamectin toxicity in time dependent manner in S.litura.