Summary. Aim: Aberrant Sonic hedgehog (Shh) pathway signaling has been described in small cell lung cancer (SCLC), as well discrepancies, when analyzing expression of pathway components in SCLC cell lines vs tumor biopsies. Shh key component GLI1 was evaluated in advanced SCLC and data correlated with patient survival. Materials and Methods: GLI1 expression was analyzed by quantitative real-time polymerase chain reaction in pre-treatment fresh frozen tumor biopsies of 12 advanced SCLC patients and mRNA level of GLI1 was compared in short-term vs long-term survivor’s samples (stratified by median survival, independent samples t-test). Results: Expression of GLI1 mRNA was significantly higher in long-term (> 9.6 months, n = 6) survivor’s biopsies than in short-term (≤ 9.6 months, n = 6) survivors (p = 0.0196, 95% CI: 0.000016 to 0.000147, two-tailed independent samples t-test). Conclusion: High GLI1 mRNA expression in SCLC was found to be positive prognostic marker associated with longer survival. Further research is needed for validation of these results due to the small number of patients in the study.

Collagen IV and laminin are important constituents of the basement membrane (BM). By use of immunocytochemistry we examined the occurrence and distribution of these two components in the BM beneath normal, mucoid and metaplastic epithelium of large bronchi in 22 adults suffering from chronic nonspecific lung diseases. Both collagen IV and laminin were expressed as a thin and continuous layer beneath the epithelium in most tissue specimens with normal epithelium. In a few specimens the layer showed interruptions with a patchy distribution of the immunoreactivity. Three patterns of distribution of BM components were found under the metaplastic epithelium. Total absence of immunoreactive collagen IV and laminin was the most common variant. Weak and scarce staining for both proteins in the BM characterized the second pattern. The third variant showed strong collagen IV immunoreactivity but lack of laminin. The BM beneath the mucoid epithelium was characterized by irregular distribution of collagen IV and laminin. We suggest that the occurrence and distributional pattern of the BM components are related to the type of overlying epithelium and connected with an altered synthesis of these components.

Cancer stem cells may be responsible for tumour regrowth and acquisition of resistance in small cell lung cancer (SCLC). The Hedgehog pathway regulates survival and proliferation of tissue progenitor and stem cell populations, promoting the expression of stem cell related and proliferative genes. We evaluated the Sonic Hedgehog (Shh) embryonic signalling pathway in relapsed SCLC. Expression levels of Shh related genes GLI1, SMO, SUFU, PTCH1, HHIP, BCL2, BMI, ZEB1, ZEB2, N-MYC, Twist1 were analysed by qRT-PCR in matched pre-treatment and relapsed tumour fresh frozen biopsies of three SCLC patients. Expression of each gene was compared using the paired samples t-test, as well as comparison of mean expression levels was done. Data were statistically interpreted using the MedCalc version 10.2.0.0 software. 2.9-fold lower mean mRNA expression of the major Hedgehog activation indicator GLI1 was observed in relapsed samples (p = 0.0529). Mean expression of six Shh inducible genes, PTCH1, HHIP, N-MYC, ZEB2, Twist1, ZEB1, was also downregulated by 2.6-, 2.2-, 1.9-, 1.8-, 1.2-, 1.1-fold, respectively (p = 0.4252, p = 0.1268, p = 0.2480, p = 0.1169, p = 0.1480, p = 0.7595, respectively). 1.8-fold mean expression decrease was found for Gli activator Smo (p = 0.4111). Only the Shh pathway inhibitor SUFU and two other examined Hedgehog signalling inducible genes BCL2 and BMI in relapsed SCLC showed 0.8-, 0.9-,and 0.8-fold increase of expression, respectively (p = 0.3074, p = 0.7921, and p = 0.3822, respectively). To our knowledge, this is the first report of comparison of Shh signalling in matched pre-treatment and relapsed SCLC biopsies. Our data show decreased activity for majority of Shh pathway components in relapsed SCLC, although difference did not reach statistical significance.