Search

Several lines of compelling pre-clinical evidence identify chemotherapy as a potentially double-edged sword: therapeutic efficacy on the primary tumor may in fact be counterbalanced by the induction of tumor/host reactive responses supportive for survival and dissemination of cancer cell subpopulations. This paradoxical effect of chemotherapy can affect different districts such as the primary tumor, the circulation and distant organs by simultaneously shaping properties and composition of tumor and stromal cells. At the primary tumor site, chemotherapy has been reported to promote selection of chemoresistant and disseminating tumor cells endowed with properties of cancer stem cells (CSCs) through activation of autocrine and paracrine self-renewing/survival pathways promoted jointly by therapy-selected tumor and stromal cells. Resistant CSCs represent seeds for tumor relapse and increased infiltration by immune cells, together with enhanced vascular permeability induced by chemotherapy, facilitates tumor cells intravasation, the first step of the metastatic cascade. As a consequence of primary tumor/metastasis re-shaping induced by chemotherapy, circulating tumor cells (CTCs) detected during therapy can display a shift towards a more mesenchymal and stem-like phenotype, conductive to increased ability to survive in the circulation and seed distant organs. At the metastatic site, host responses to therapy activate inflammatory pathways that ultimately facilitate tumor cells extravasation and metastatic colonization. Finally, cooperation of immune cells and endothelial cells at perivascular niches favors the extravasation of tumor cells endowed with high potential for metastasis initiation and protects them from chemotherapy. This review highlights the paradoxical pro-metastatic effects of chemotherapy linking reactive responses to treatment to tumor relapse and metastasis formation through primary tumor remodeling and generation of a favorable pro-metastatic niche.

Background Although screening programmes of smokers have detected resectable early lung cancers more frequently than expected, their efficacy in reducing mortality remains debatable. To elucidate the biological features of computed tomography (CT) screening detected lung cancer, we examined the mRNA signatures on tumours according to the year of detection, stage and survival. Methods Gene expression profiles were analysed on 28 patients (INT–IEO training cohort) and 24 patients of Multicentre Italian Lung Detection (MILD validation cohort). The gene signatures generated from the training set were validated on the MILD set and a public deposited DNA microarray data set (GSE11969). Expression of selected genes and proteins was validated by real-time RT-PCR and immunohistochemistry. Enriched core pathway and pathway networks were explored by GeneSpring GX10. Findings A 239-gene signature was identified according to the year of tumour detection in the training INT–IEO set and correlated with the patients' outcomes. These signatures divided the MILD patients into two distinct survival groups independently of tumour stage, size, histopathological type and screening year. The signatures can also predict survival in the clinically detected cancers (GSE11969). Pathway analyses revealed tumours detected in later years enrichment of the PI3K/PTEN/AKT pathway, with up-regulation of PDPK1, ITGB1 and down-regulation of FOXO1A. Analysis of normal lung tissue from INT–IEO cohort produced signatures distinguishing patients with early from late detected tumours. Interpretation The distinct pattern of “indolent” and “aggressive” tumour exists in CT-screening detected lung cancer according to the gene expression profiles. The early development of an aggressive phenotype may account for the lack of mortality reduction by screening observed in some cohorts., Highlights • Lung cancers detected in the first two years of screening program are less aggressive than the ones identified subsequently. • A mRNA gene signature separates tumours from the initial and late years of screening and correlated with outcomes. • Early stage lung cancers can be divided into “indolent” and “aggressive” with distinct biological basis.

The existence of specific cellular subpopulations within primary tumors with increased tumorigenic potential and chemotherapy resistance (tumor-initiating cells, TICs) holds great therapeutic implications. Resistant cells can remain quiescent for long periods and be responsible for local relapses and metastasis. We and others have previously described in non–small-cell lung cancer the presence of cisplatin-resistant CD133+ cells with tumor-initiating potential and co-expression of CXCR4 as possible indicator of TICs with disseminating potential. In this study, we report, by in vitro cell fate tracing systems, heterogeneity within the TIC compartment with a highly quiescent pool and a slowly dividing subpopulation, both containing CD133+ cells but respectively enriched for CD133+/CXCR4− and CD133+/CXCR4+ cells. Pretreatment with differentiating agent all-trans retinoic acid counteracts cisplatin resistance specifically of the slowly dividing compartment indicating effect on CD133+/CXCR4+ cells. The same effects are appreciable also in vivo in patient-derived xenografts, where several cycles of all-trans retinoic acid and cisplatin treatment are able to stably reduce this fraction of TICs and tumor dissemination. Thus, partially affecting the heterogeneous TICs compartment, differentiating therapy has promising effects in counteracting cisplatin resistance of CD133+ cells, reducing both local tumor growth and dissemination. In addition, our approach discloses a further level of complexity of chemotherapy-resistant CD133+ TICs, revealing phenotypical and functional heterogeneity of the cancer stem cell compartment in lung cancer.

Loss of FHIT expression and p53 mutations are critical events in the early stages of lung carcinogenesis. The restoration of Fhit function in FHIT-negative cancer cells has been reported to cause tumour suppression by inhibition of cell proliferation and/or activation of apoptotic pathways. However, the studies designed to elucidate the biological role of Fhit and its potential interaction with p53 have produced conflicting results. We investigated here the effects of the simultaneous restoration of FHIT and p53 in Calu-1 cells by using a hormone-inducible gene expression system. We demonstrate that the restoration of FHIT expression reinforces the anti-proliferative effect associated with the simultaneous replacement of p53. Indeed, a more pronounced inhibition of cell proliferation associated with an earlier and higher induction of p21(waf1) mRNA and protein expression was observed in Fhit/p53-expressing cells compared with cells expressing p53 alone. This effect was not due to Fhit-mediated up-regulation of p53 expression; in fact p53 protein was expressed at the same level in both FHIT-positive and FHIT-negative cell clones. Consistent with this result, Fhit did not affect the expression of MDM2, a protein known to interact directly with p53 and target p53 for proteolytic degradation, thus down-regulating its activity.

To evaluate the relevance of fragile histidine triad (FHIT) status in relation to drug treatment, we analyzed the sensitivity of the Fhit-negative non-small cell lung cancer (NSCLC) cell line NCI-H460 to different drugs, after treatment with an adenoviral vector expressing the FHITtransgene. Expression of Fhit resulted in reduced sensitivity to etoposide, doxorubicin, and topotecan. This feature was associated with Fhit-induced downregulation of DNA topoisomerases I and II. In contrast, expression of Fhit did not modulate sensitivity to Taxol, but produced a slight increase in sensitivity to cisplatin, as shown by colony-forming assays. Analysis of apoptosis revealed that, after cisplatin exposure, the number of apoptotic cells was two-fold higher in Fhitexpressing H460 cells. Moreover, it appeared that wildtype p53 was required for sensitization to cisplatin because the effect was marginal in A549 and Calu-1 cells, where the p53 pathway is altered and simultaneous restoration of p53 and Fhit in Calu-1 cells increased cisplatin sensitivity. Fhit could also partially restore sensitivity to cisplatin in Bcl-2- and BCl-xL-overexpressing H460 cells that are normally resistant to this drug. Our results support the possible relevance of FHIT in cisplatin-based chemotherapy as well as in the reversal of drug resistance in NSCLC.

Aim: CD133 positive cells have been identified as tumor initiating cells in non-small cell lung cancer (NSCLC) and have been shown to be resistant to conventional cytotoxic chemotherapy in experimental studies, suggesting a possible role in chemoresistance and disease relapse. However their prognostic relevance in the context of clinical treatment of NSCLC has not been fully investigated. Methods: We analyzed tumor samples from 60 consecutive NSCLC patients with stage IIIA-B undergoing neo-adjuvant chemotherapy with platinum-based regimens followed by radically surgery. Tumor specimen collection included pre-treatment mediastinal lymph-node biopsies (n = 23) and post-treatment surgical specimens (25 from lymph-nodes and 52 from primary tumors). CD133 status was determined by immunohistochemistry and correlations with clinico-pathological variables were evaluated using univariable and multivariable Cox models. Results: CD133 positive cells (mean 5% of total tumor cells, range 1-40%) were detected in 35% of pre-treatment samples and after chemotherapy in 38% and 32% of resected primary tumors and metastatic lymph-nodes, respectively. When both lymph nodes and primary tumor were available (24 patients) no correlation was found between CD133 status, possibly indicating different dynamics in primary tumor maintenance and dissemination. CD133 positive cells were detected more frequently in tumors with best response to chemotherapy (by ≥30% size reduction: 14/28, 50% vs. 6/24, 25%) suggesting enrichment of chemoresistant cells after treatment. CD133 positivity after induction chemotherapy was correlated with higher risk of local and distant recurrence (73% vs 53%), especially in patients with pre-treatment CD133+ lymph nodes (87% vs. 53%). Finally, positivity for CD133 after treatment seems to be correlated with worse overall survival (HR 2.42, 95% CI: 0.93-6.32, p = 0.184). Conclusions: Investigation of tumors after chemotherapy provides indirect evidence of chemoresistance of CD133+ cells. CD133 positive cells are correlated with worse prognosis in neo-adjuvant treatment of locally advanced NSCLC and could provide clinical relevant information for personalized therapies. Disclosure: All authors have declared no conflicts of interest.