"APUD" cells: fact and fiction

Small-cell lung cancer: what we know, what we need to know and the path forward

Small-cell lung cancer (SCLC) is a deadly tumour accounting for approximately 15% of lung cancers and is pathologically, molecularly, biologically and clinically very different from other lung cancers. While the majority of tumours express a neuroendocrine programme (integrating neural and endocrine properties), an important subset of tumours have low or absent expression of this programme. The probable initiating molecular events are inactivation of TP53 and RB1, as well as frequent disruption of several signalling networks, including Notch signalling. SCLC, when diagnosed, is usually widely metastatic and initially responds to cytotoxic therapy but nearly always rapidly relapses with resistance to further therapies. There were no important therapeutic clinical advances for 30 years, leading SCLC to be designated a 'recalcitrant cancer'. Scientific studies are hampered by a lack of tissue availability. However, over the past 5 years, there has been a worldwide resurgence of studies on SCLC, including comprehensive molecular analyses, the development of relevant genetically engineered mouse models and the establishment of patient-derived xenografts. These studies have led to the discovery of new potential therapeutic vulnerabilities for SCLC and therefore to new clinical trials. Thus, while the past has been bleak, the future offers greater promise.

Functional facets of the pulmonary neuroendocrine system

Pulmonary neuroendocrine cells (PNECs) have been around for 60 years in the scientific literature, although phylogenetically they are ancient. Their traditionally ascribed functions include chemoreception and regulation of lung maturation and growth. There is recent evidence that neuroendocrine (NE) differentiation in the lung is regulated by genes and pathways that are conserved in the development of the nervous system from Drosophila to humans (such as achaete-scute homolog-1), or implicated in the carcinogenesis of the nervous or NE system (such as the retinoblastoma tumor suppressor gene). In addition, complex neural networks are in place to regulate chemosensory and other functions. Even solitary PNECs appear to be innervated. For the first time ever, we have mouse models for lung NE carcinomas, including the most common and virulent small cell lung carcinoma. Moreover, PNECs may be important for inflammatory responses, and pivotal for lung stem cell niches. These discoveries signify an exciting new era for PNECs and are likely to have therapeutic and diagnostic applications.

Stem-cell origin of metastasis and heterogeneity in solid tumours

An explanation for the inherently metastatic and heterogeneous nature of cancers may be their derivation from distinct stem cells. The type of stem cell from which a neoplasm arises determines both the metastatic potential and the phenotypic diversity of that neoplasm. Hence, tumours originating from an early stem cell or its progenitor cells metastasise readily and have a more heterogeneous phenotype, whereas tumours originating from a later stem cell or its progenitor cells have limited metastatic potential and a more homogeneous phenotype. Further investigation of the role of stem cells in the development of cancer may lead to the discovery of novel diagnostic tools, prognostic markers, and therapeutic targets in the battle against cancer.

Morphological-histochemical study of intestinal carcinoids and K-ras mutation analysis in appendiceal carcinoids

Intestinal carcinoids are potentially malignant neoplasms. Their histogenesis and pathogenesis are currently uncertain. The morphological and histochemical characteristics of twenty intestinal carcinoids are studied. The primary sites of three mucin-producing tumors were examined by electron microscope. Furthermore 11 appendiceal carcinoids were analysed by the polymerase chain reaction (PCR) for the detection of ras and p53 point mutations. Microscopically all carcinoids were of mixed type. Focal mucin production was evident in three carcinoids that metastasised to regional lymph nodes. HID-Alcian blue staining proved that mucin in both primary and secondary foci did not belong to the sulphated group. The secretory granules and mucin droplets found in a single neoplastic cell suggest that carcinoids of the small intestine and some of the appendix arise from the endoderm. Neither ras nor p53 mutations were detected. It seems that ras oncogenes are probably not involved in the pathogenesis of appendiceal carcinoids.

Investigation on serum neurone-specific enolase in prostate cancer diagnosis and monitoring: comparative study of a multiple tumor marker assay

A quadruple tumor marker serotest assay (neurone-specific enolase, NSE, prostate-specific antigen, PSA, prostatic acid phosphatase, PAP, and carcino-embryonic antigen, CEA) was performed on sera from both 63 patients with untreated prostate cancer and 135 patients treated with orchiectomy, flutamide, diethylstilbestrol (DES), cyproterone acetate (CPA), and Estracyt. In untreated patients with local tumor elevated blood NSE concentrations were found more frequently (10/35, 28.6%) than in untreated subjects with disseminated disease (3/28, 10.7%). Elevated NSE values were measured more frequently in nonresponders to therapy 10/46 (21.7%), than in responders during prostate cancer partial remission (2/89, 2.2%). In none of NSE-positive neoplasms a small cell prostate cancer has been histologically detected. Many of NSE-positive tumors are also closely associated with elevated blood CEA values. The applied anticancer drugs were inefficient in the normalization of neither one from the pair of elevated NSE and CEA concentrations (regardless of the numerical values of the other two markers, PSA and PAP), but their values were found to decline occasionally only after surgical treatment. In patients with raised PSA, PAP, and CEA levels but with a normal NSE value, the application of the same treatment strategies was in the most of subjects sufficient to provoke either temporary or even lasting tumor response to therapy. Hence, it appears that the assessment of the NSE serotest, despite its minimal value in the overall tumor staging and monitoring, might furnish the decision-making step related to the treatment of aggressive prostate cancer with an additional and powerful tool.