Ectopic hormone production by small cell undifferentiated carcinomas

Prognostic Value of Prepro-Gastrin Releasing Peptide in Lung Cancer Patients; NCI-Prospective Study

Background:

Prior series investigated the expression of prepro-gastrin releasing peptide (prepro-GRP) in the peripheral blood of lung cancer patients. Our aim was to assess any prepro-GRP role as a prognostic factor for small cell lung cancer (SCLC) and NSCLC and correlations with clinical presentation and treatment outcome.

Methods:

A prospective study was conducted during the time period from the beginning of January 2012 till the end of January 2014. Prepro-GRP expression was analysed using a nested RT-PCR assay in peripheral blood of 62 untreated lung cancer patients attending the National Cancer Institute (NCI), Cairo University, and 30 age and sex matched healthy volunteers.

Results:

Among the 62 lung cancer cases, there were 24 (38.7%) SCLC, and 38 (61.3%) NSCLC (10 squamous cell carcinomas, 12 adenocarcinomas, 11 large cell carcinomas, 4 undifferentiated carcinomas, and 1 adenosquamous carcinoma). Twenty six patients (41.9%) were prepro-GRP positive. Prepro-GRP expression was higher (58.3%) among SCLC patients compared to NSCLC (squamous cell carcinoma (15.4%), large cell carcinoma (36.4%), and adenocarcinoma (25%)). Mean OS among prepro-GRP negative cases was longer than that among preprogastrin positive cases (17.6 vs 14.9 months). The mean PFS durations among preprogastrin negative versus positive cases were 7.7 vs 4.6 months (p= 0.041). No difference in response to chemotherapy was identified between the groups (p=0.983).

Conclusion:

Prepro-GRP is suggested to be a useful prognostic marker for lung cancer patients, especially with the fast- growing, bad prognostic SCLC type. More studies should aim at detailed understanding of the mechanisms of prepro-GRP action and its use in monitoring the response to treatment in a larger cohort.

Sensitive detection of small cell lung carcinoma cells by reverse transcriptase-polymerase chain reaction for prepro-gastrin-releasing peptide mRNA

BACKGROUND

Gastrin-releasing peptide (GRP) is an autocrine growth factor in patients with small cell lung carcinoma (SCLC). The authors developed a reverse transcriptase-polymerase chain reaction (RT-PCR) assay for the detection of SCLC cells in the peripheral blood and the pleural effusion using preproGRP mRNA as a target.

METHODS

The current study was conducted to determine the utility of preproGRP-specific nested RT-PCR on the peripheral blood, bone marrow, and pleural effusion samples from 32 patients with SCLC, 39 patients with non-small cell lung carcinoma (NSCLC), 28 patients with nonmalignant pulmonary disease, and 20 healthy volunteers. The internal primers were designed to amplify a 244-base pair PCR product, a sequence encompassing exon 1 and exon 2 by the nested RT-PCR assay.

RESULTS

Amplification of the preproGRP message was detected in SCLC cell lines (LU165, SBC1, SBC2, and SBC3) but not in other NSCLC cell lines (A549, ABC1, EBC1, and Oka-1). The SCLC cells (LU165) were detected in dilutions of tumor cells of up to 10(-7) in hematopoietic cells from healthy donors. The preproGRP mRNA was detected in 16 of 32 (50%) blood samples, 2 of 11 (18%) marrow samples, and in all 6 (100%) pleural effusion samples. Blood samples gave positive results in 11 of 19 (58%) patients with extensive disease compared with 5 of 13 (38%) patients with limited disease. In contrast, only 1 blood sample (2.6%) from a patient with lung adenocarcinoma gave a positive result among patients with NSCLC. No other samples of blood, bone marrow, and pleural effusion from patients with NSCLC and none of the blood samples from patients with nonmalignant diseases and healthy volunteers were positive.

CONCLUSIONS

The current RT-PCR approach may be a sensitive and specific assay to detect SCLC cells in circulating blood as well as in pleural effusions from SCLC patients.

Case report: renal phosphate wasting, syndrome of inappropriate antidiuretic hormone, and ectopic corticotropin production in small cell carcinoma

Renal phosphate wasting related to a tumor (oncogenous osteomalacia) is a rare disorder usually associated with benign mesenchymal tumors. In this article, the authors describe a man with renal phosphate wasting and the syndrome of inappropriate antidiuretic hormone associated with small cell carcinoma. Chemotherapy markedly reduced tumor burden and was associated with normalization of renal phosphate handling and serum sodium. With recurrence, renal phosphate wasting and the syndrome of inappropriate antidiuretic hormone developed again, with the additional complication of hypercortisolism secondary to ectopic corticotropin production. The authors report the rare occurrence of renal phosphate wasting with small cell carcinoma (5 previously reported cases) and the unique co-existence of this paraneoplastic syndrome with the syndrome of inappropriate antidiuretic hormone and ectopic corticotropin production.

Calcitonin gene-related peptide in medullary thyroid carcinomas: characterization of molecular forms including the amidated C-terminus

CGRP was extracted from three familial and four sporadic medullary thyroid carcinomas (MTC) and was measured by an assay specific for the amidated C-terminus. The antibody showed equal affinity for alpha- and beta-CGRP. All tumors contained high concentrations of CGRP (range: 63-7889 pmol/g) compared to spinal cord (86 pmol/g), thyroid gland (4 pmol/g), and two small-cell lung carcinomas (4 and 1 pmol/g, respectively). The concentration of calcitonin (CT) was determined with an assay specific for an epitope involving the midportion and C-terminal end of the molecule. In six of the seven tumors investigated, concentrations of CT were found to be higher than for CGRP. Gel chromatography showed heterogeneity with respect to CGRP immunoreactivity. Thus, in all seven extracts, three peaks were seen with Kd values 0.37, 0.63, and 0.80, respectively. This profile of immunoreactive CGRP was similar to that obtained from human medulla spinalis, thereby indicating normal posttranslational processing of pro-CGRP in MTC tumors. Further characterization of the three main peaks identified by gel chromatography was performed on pooled fractions from one of the tumors using HPLC, sequencing, and mass spectrometry. The immunoreactive peak with Kd 0.37 was identified as human beta-CGRP, the peak with Kd 0.63 as 19-37 beta-CGRP, and the peak with Kd 0.80 as 25-37 beta-CGRP. No alpha-CGRP was identified in this tumor. This indicates selective expression of beta-CGRP, at least in the tumor investigated.

Partial characterization of IR-alpha-MSH peptides found in melanoma tumors

Our previous work indicated that IR-alpha-MSH (immunoreactive alpha-melanocyte-stimulating hormone) plasma levels are three times as high in melanoma patients with progressing disease than in disease-free patients, and that the melanoma tumor itself may be the source of IR-alpha-MSH. Further identification of the material in tumor extracts has been carried out in this study, and the results presented here show that the immunoreactivity is associated with a major fraction of about 16 kDa and another of 5-9 kDa. Significant amounts of the immunoreactive material were also found in human melanoma cells but not in culture supernatants. The presence of this material may be related to the melanogenic status of the tumor cells. We have estimated the intracellular IR-alpha-MSH to be within a 0.4 to 2.3 nM range in melanoma tumor cells. We have investigated the melanogenic effect of the IR-alpha-MSH material and its relationship to alpha-MSH. Purified extracts both from metastases and cultured cells were found to promote frog skin darkening as well as tyrosinase activity in Cloudman S91 melanoma cells. The IR material could also displace labeled alpha-MSH from its binding sites in human melanoma cells. Our data clearly indicate that melanoma cells engage in an autocrine production of alpha-MSH-like bioactive peptides by melanoma cells, of larger mol.wt., which are able to bind to MSH receptors. These peptides may be involved in the regulation of melanogenesis and possibly in the growth and proliferation of melanoma cells by an autocrine/paracrine mechanism.

Voltage-sensitive calcium channels in a human small-cell lung cancer cell line

Utilizing the whole-cell patch-clamp method we assessed the Ca2+ current (ICa) in well-established cell lines from human small-cell carcinoma (SCC) of the lung, NCI-H209 and NCI-H187. The Ca2+ current was readily observed in H209 tumour cells (90% of the cells tested), whereas H187 tumour cells only occasionally expressed Ca2+ channels (26% of the cells tested). H209 Ca2+ current was evoked by potentials greater than -30 mV and exhibited partial inactivation over the duration of a 40 ms command potential. This inward current was unchanged by alteration of the holding potential from -80 to -40 mV and the activation phase of the Ca2+ current was best fitted by Hodgkin-Huxley m(t)2 kinetics. H209 Ca2+ current was reduced over 80% by verapamil (100 microM), whereas w-conotoxin (5 microM) appeared to be without effect. In contrast, H209 Ca2+ current was rapidly abolished by nifedipine (10 microM), strongly suggesting the presence of L-type Ca2+ channels. Voltage-gated Ca2+ channels may be important to the secretion of ectopic hormones and the etiology and pathogenesis of Lambert-Eaton syndrome, an autoimmune disorder of the motor nerve terminal in which autoantibodies directed against voltage-gated Ca2+ channels are produced.