Clones and subclones in the lung cancer field

Inhibitory effect of O-propargyllawsone in A549 lung adenocarcinoma cells

BACKGROUND

Lung cancer is the deadliest type of cancer in the world and the search for compounds that can treat this disease is highly important. Lawsone (2-hydroxy-1,4-naphtoquinone) is a naphthoquinone found in plants from the Lawsone genus that show a high cytotoxic effect in cancer cell lines and its derivatives show an even higher cytotoxic effect.

METHODS

Sulforhodamine B was used to evaluate the cytotoxic activity of compounds on tumor cells. Clonogenic assay was used to analyze the reduction of colonies and wound healing assay to the migratory capacity of A549 cells. Apoptosis and necrosis were analyzed by flow cytometer and Giemsa staining. Hemolysis assay to determine toxicity in human erythrocytes.

RESULTS

Lawsone derivatives were evaluated and compound 1 (O-propargyllawsone) was the one with the highest cytotoxic effect, with IC50 below 2.5 µM in A549 cells. The compound was able to reduce colony formation and inhibit cell migration. Morphological changes and cytometry analysis show that the compound induces apoptosis and necrosis in A549 cells.

CONCLUSIONS

These results show that O-propargyllawsone show a cytotoxic effect and may induce apoptosis in A549 cells.

Game of clones: Battles in the field of carcinogenesis

Recent advances in bulk sequencing approaches as well as genomic decoding at the single-cell level have revealed surprisingly high somatic mutational burdens in normal tissues, as well as increased our understanding of the landscape of "field cancerization", that is, molecular and immune alterations in mutagen-exposed normal-appearing tissues that recapitulated those present in tumors. Charting the somatic mutational landscapes in normal tissues can have strong implications on our understanding of how tumors arise from mutagenized epithelium. Making sense of those mutations to understand the progression along the pathologic continuum of normal epithelia, preneoplasias, up to malignant tissues will help pave way for identification of ideal targets that can guide new strategies for preventing or eliminating cancers at their earliest stages of development. In this review, we will provide a brief history of field cancerization and its implications on understanding early stages of cancer pathogenesis and deviation from the pathologically "normal" state. The review will provide an overview of how mutations accumulating in normal tissues can lead to a patchwork of mutated cell clones that compete while maintaining an overall state of functional homeostasis. The review also explores the role of clonal competition in directing the fate of normal tissues and summarizes multiple mechanisms elicited in this phenomenon and which have been linked to cancer development. Finally, we highlight the importance of understanding mutations in normal tissues, as well as clonal competition dynamics (in both the epithelium and the microenvironment) and their significance in exploring new approaches to combatting cancer.

Primary Tumor Resection Improves Survival for EGFR-TKI-Treated Patients With Occult M1a Lung Adenocarcinoma

Background

The role of primary tumor resection in occult M1a lung adenocarcinoma remains unclear, especially for patients receiving targeted therapy. The purpose of this study is to assess the effect of primary tumor resection on overall survival (OS) in lung adenocarcinoma patients with occult pleural disseminations receiving targeted therapy.

Methods

Lung adenocarcinoma patients with intraoperatively-confirmed occult pleural dissemination (M1a), who hospitalized in the Department of Thoracic Surgery in Fudan Shanghai Cancer Center from May 2008 to December 2017 and received EGFR-TKIs therapy, were enrolled. Log-rank tests were used to compare the survival differences between groups.

Results

34 patients receiving EGFR-TKIs were enrolled. The majority of them were never smokers (29/34, 85.3%). Among the enrolled patients, 20 (58.8%) patients underwent primary tumor resection, while 14 (41.2%) patients not. There was no distributional difference of baselines between patients undergoing and not undergoing primary tumor resection. Further analyses demonstrated that the patients undergoing primary tumor resection had a prolonged OS compared with those not (log-rank P= 0.042). The 2-year and 5-year OS for patients receiving primary tumor resection and EGFR-TKIs was 90.0% and 60.1%.

Conclusions

Primary tumor resection was associated with improved survival in patients with occult intraoperatively-confirmed M1a adenocarcinoma receiving EGFR-TKIs.

Preneoplasia of lung cancer

As with other epithelial cancers, lung cancer develops over a period of several years or decades via a series of progressive morphological changes accompanied by molecular alterations that commence in histologically normal epithelium. However the development of lung cancer presents certain unique features that complicates this evaluation. Anatomically the respiratory tree may be divided into central and peripheral compartments having different gross and histological anatomies as well as different functions. In addition, there are three major forms of lung cancer and many minor forms. Many of these forms arise predominantly in either the central or peripheral compartments. Squamous cell and small cell carcinomas predominantly arise in the central compartment, while adenocarcinomas predominantly arise peripherally. Large cell carcinomas are not a single entity but consist of poorly differentiated forms of the other types and, possibly, some truly undifferentiated "stem cell like" tumors. The multistage origin of squamous cell carcinomas, because of their central location, can be followed more closely than the peripherally arising adenocarcinomas. Squamous cell carcinomas arise after a series of reactive, metaplastic, premalignant and preinvasive changes. However, long term observations indicate that not all tumors follow a defined histologic course, and the clinical course, especially of early lesions, is difficult to predict. Peripheral adenocarcinomas are believed to arise from precursor lesions known as atypical adenomatous hyperplasias and may have extensive in situ growth before becoming invasive. Small cell carcinomas are believed to arise from severely molecularly damaged epithelium without going through recognizable preneoplastic changes. The molecular changes that occur prior to the onset on invasive cancers are extensive. As documented in this chapter, they encompass all of the six classic Hallmarks of Cancer other than invasion and metastasis, which by definition occur beyond preneoplasia. A study of preinvasive lung cancer has yielded much valuable biologic information that impacts on clinical management.

Proliferative changes in the bronchial epithelium of former smokers treated with retinoids

BACKGROUND

Retinoids have shown antiproliferative and chemopreventive activity. We analyzed data from a randomized, placebo-controlled chemoprevention trial to determine whether a 3-month treatment with either 9-cis-retinoic acid (RA) or 13-cis-RA and alpha-tocopherol reduced Ki-67, a proliferation biomarker, in the bronchial epithelium.

METHODS

Former smokers (n = 225) were randomly assigned to receive 3 months of daily oral 9-cis-RA (100 mg), 13-cis-RA (1 mg/kg) and alpha-tocopherol (1200 IU), or placebo. Bronchoscopic biopsy specimens obtained before and after treatment were immunohistochemically assessed for changes in the Ki-67 proliferative index (i.e., percentage of cells with Ki-67-positive nuclear staining) in the basal and parabasal layers of the bronchial epithelium. Per-subject and per-biopsy site analyses were conducted. Multicovariable analyses, including a mixed-effects model and a generalized estimating equations model, were used to investigate the treatment effect (Ki-67 labeling index and percentage of bronchial epithelial biopsy sites with a Ki-67 index > or = 5%) with adjustment for multiple covariates, such as smoking history and metaplasia. Coefficient estimates and 95% confidence intervals (CIs) were obtained from the models. All statistical tests were two-sided.

RESULTS

In per-subject analyses, Ki-67 labeling in the basal layer was not changed by any treatment; the percentage of subjects with a high Ki-67 labeling in the parabasal layer dropped statistically significantly after treatment with 13-cis-RA and alpha-tocopherol treatment (P = .04) compared with placebo, but the drop was not statistically significant after 9-cis-RA treatment (P = .17). A similar effect was observed in the parabasal layer in a per-site analysis; the percentage of sites with high Ki-67 labeling dropped statistically significantly after 9-cis-RA treatment (coefficient estimate = -0.72, 95% CI = -1.24 to -0.20; P = .007) compared with placebo, and after 13-cis-RA and alpha-tocopherol treatment (coefficient estimate = -0.66, 95% CI = -1.15 to -0.17; P = .008).

CONCLUSIONS

In per-subject analyses, treatment with 13-cis-RA and alpha-tocopherol, compared with placebo, was statistically significantly associated with reduced bronchial epithelial cell proliferation; treatment with 9-cis-RA was not. In per-site analyses, statistically significant associations were obtained with both treatments.

The convergent development of molecular-targeted drugs for cancer treatment and prevention

Advances in our understanding of multistep and field carcinogenesis are erasing the clear demarcation of intraepithelial neoplasia from invasive neoplasia. The growing ability to define a very high risk of cancer is forging important commonalities between prevention and therapy, such as in potential prognostic/predictive markers, agents, and side effects that patients would be willing to tolerate, and the logistics of definitive trials. The emergence of promising new molecular-targeted agents and new technologies for screening and early detection provides new opportunities for applying clinical trial designs that integrate therapy and prevention end points. Such trials may be used to facilitate targeted drug development and help identify strategies for both cancer prevention and advanced cancer therapy. These several advances are creating a convergence of cancer therapy with cancer prevention that promises to streamline the development of targeted drugs and improve the control of major cancers.

Chromosomal abnormalities in bronchial epithelium from smokers, nonsmokers, and lung cancer patients

The identification of individuals who are at greatest risk of developing lung cancer would greatly improve diagnosis and possibly lead to early treatment. To study the use of karyotypes for this purpose, we used short-term human bronchial epithelial (hBE) cell cultures from nonsmokers, smokers, and lung cancer patients. Twenty-five metaphases were scored for hBE cell cultures obtained from 32 patients: 8 were nonsmokers, and 24 had a history of smoking (of whom 11 had had lung cancer surgery). The number of abnormal metaphases ranged from 0 to 4 per cell culture. No overall differences in the number of abnormal metaphases were observed between nonsmokers and smokers or between lung cancer patients and non-lung cancer patients. The most commonly observed abnormalities were structural changes in chromosome 1 (six cultures), loss of chromosome 17 (six cultures), and trisomy of chromosome 20 (three cultures). These specific alterations were found almost exclusively in patients with a history of tobacco smoking. The results did not indicate that general chromosomal abnormalities are a useful marker for tobacco smoke exposure or cancer risk.

Fluorescent bronchoscopy: contribution for lung cancer screening?

The majority of early lesions, even when centrally located, is missed by conventional white-light (WL) bronchoscopy. Fluorescent bronchoscopy is a promising tool in localising early malignant changes in the central airways, because it is significantly more sensitive than WL bronchoscopy. Originally, drug-induced fluorescence has been used, but today autofluorescence bronchoscopy is more common in relation to its simplicity and advantages. Different systems are available which yield comparable results. However, there are no studies comparing all systems. The disadvantage is the low specificity of the method. Fluorescent bronchoscopy will be more effective if carried out in high-risk patients and/or embedded in a program of preprocedural evaluation of sputum and together with a CT examination of the thorax. But a reduction of mortality as a result of such efforts has not been shown until the present time.

Analytical and statistical methods to evaluate microsatellite allelic imbalance in small amounts of DNA

Microsatellite analysis is a powerful tool for the assessment of genetic instability and loss of heterozygosity in cancer cells. However, most human tumors harbor significant numbers of normal cells, which may contribute to false-negative results. Recent techniques based on fluorescently labeled primers and semiautomated capillary electrophoresis of polymerase chain reaction (PCR) products allow a reliable quantitative assessment of (PCR) products while requiring very small numbers of cells. We report a highly sensitive protocol for the semiautomated analysis of allelic imbalance based on time-release PCR and capillary electrophoresis. With this protocol, as few as 100 cells can be used to reliably assess allelic imbalance (AI) in DNA samples. Using a panel of seven microsatellite markers, we determined allelic variation in a large set of heterozygous lymphocyte DNA samples and examined the use of different statistical analysis techniques. Using these statistical approaches, we describe a calibration method to evaluate AI from microsatellite results. Using a simple formula, cutoff points at preset confidence levels are used to decide whether allelic imbalance exists in a given sample at the loci under investigation. Our method allows the reliable detection of AI with very small amounts of DNA, and is sufficiently quantitative to assess allelic ratios in nonclonal tissue specimens.

The curative potential of intraluminal bronchoscopic treatment for early-stage non-small-cell lung cancer

Bronchoscopic treatment modalities such as lasers, electrocautery, cryotherapy, photodynamic therapy, and brachytherapy are potentially curative for patients with very-early-stage non-small-cell lung cancer (NSCLC) in the central airways. Previously, studies had primarily focused on the effectiveness of surgery, surgical bronchoplasty, and photodynamic therapy. The cure rate of intraluminal bronchoscopic treatment is strongly related to the patient's functional status and tumor stage. Intraluminal tumors are curable bronchoscopically when they are accessible to the fiberoptic bronchoscope, strictly intraluminal, and superficial with visible proximal and distal tumor margins. Early-stage cancer infiltrating deeper into the bronchial wall may already harbor metastases to the regional lymph nodes; hence, curative intraluminal treatment is not feasible. The use of new diagnostic tools (eg, high-resolution computed tomography, autofluorescence bronchoscopy, and endobronchial ultrasound) may improve staging to select the category of patients in whom intraluminal bronchoscopic therapy with curative intent is appropriate. An accurate intraluminal tumor staging will improve our ability to exploit the curative potential of many bronchoscopic techniques for complete tumor eradication in patients with very-early-stage intraluminal NSCLC in their central airways. The use of bronchoscopic treatment as a less morbid alternative than surgical resection will benefit patients most when tumor is detected at the earliest stage possible.

Patterns of chromosomal aberrations in urinary bladder tumours and adjacent urothelium

Bladder cancer is often characterized by recurrent and multifocal growth, and tumours are frequently accompanied by precancerous alterations of the surrounding urothelium. These findings have led to the hypothesis that cells from areas of genetically aberrant but morphologically non-cancerous or even unremarkable mucosa may be the source of bladder carcinomas. Fluorescence in situ hybridization (FISH) was performed using ten probes targeting five different chromosomes that are known to be frequently altered in bladder cancer (centromere 1, 8, 9, 11, 17 and 1p36, 8p23, 9p21, 11q13, 17p13) on paraffin-embedded tissue sections of 11 superficial bladder cancers. Copy number changes of the tumours were compared to those in the urothelium adjacent to the tumour. Eleven of 11 (100%) tumours and eight of 11 (73%) samples of adjacent urothelium showed copy number changes of at least one chromosome. The occurrence of similar patterns of chromosomal aberrations in the tumours and their associated urothelium supports the hypothesis of a clonal relationship. It is concluded that FISH analysis targeting five different chromosomes is more sensitive than conventional histology for distinguishing between neoplastic and normal cells of the urothelium.

Fluorescence bronchoscopy for early detection of lung cancer: a clinical perspective

The conventional method of bronchoscopy has only a 30% sensitivity to detect early stage cancer in the central airways. For patients with positive sputum cytology who clearly harbor early cancers, repeat and lengthy sessions of bronchoscopies are required for accurate localization of these lesions. This leads to a significant delay in obtaining the diagnosis, postponing an appropriate treatment and reduces the chance for cure. There are valid reasons for improving the detection rate of early stage lung cancers. The number of individuals at risk forms a large population, the outcome of patients treated with early stage cancer has been shown to be better and bronchoscopic treatments, e.g. photodynamic therapy and electrocautery, are currently alternatives for surgical resection. Finding more early stage cancers by screening the population at risk and accurate staging to enable treatment at the earliest stage feasible, may improve the dismal prognosis of many patients. This article deals with the clinical background and current problems in early detection of lung cancer and discusses our expectations regarding new developments in bronchoscopy for early detection, accurate staging and treatment of lung cancer.

Loss of chromosome arms 3p and 9p and inactivation of P16 (INK4a) in normal epithelium of patients with primary lung cancer

The accumulation of genetic alterations in the respiratory epithelium may give rise to cancer and often is accompanied by a series of histologic alterations over a period of several years. Recent studies have identified some molecular alterations in histologically normal-appearing epithelium among patients with lung cancer. To extend these observations, we investigated clonal genetic alterations by using fluorescence in situ hybridization (FISH) analysis and immunohistochemistry in 69 biopsy samples of histologically normal-appearing bronchial epithelium from 22 patients with or without lung cancer. Thirty-seven biopsy specimens from 13 patients were examined for loss of 3p14, and 48 biopsy specimens from 18 patients were examined for loss at 9p21 by FISH. P16(INK4a) expression was analyzed in 54 biopsy samples from 19 patients. In at least one biopsy specimen from five of the 13 patients with primary lung cancer, FISH or immunohistochemistry detected loss of the 3p14 or 9p21 region. In contrast, no alterations were detected for the same regions in the nine patients without primary lung cancer. Our results support the concept that the normal epithelial surface of large bronchi of patients with lung cancer has molecular changes suggestive of the outgrowth of numerous clonal foci.

A growth-constrained environment drives tumor progression invivo

We recently have shown that selective growth of transplanted normal hepatocytes can be achieved in a setting of cell cycle block of endogenous parenchymal cells. Thus, massive proliferation of donor-derived normal hepatocytes was observed in the liver of rats previously given retrorsine (RS), a naturally occurring alkaloid that blocks proliferation of resident liver cells. In the present study, the fate of nodular hepatocytes transplanted into RS-treated or normal syngeneic recipients was followed. The dipeptidyl peptidase type IV-deficient (DPPIV(-)) rat model for hepatocyte transplantation was used to distinguish donor-derived cells from recipient cells. Hepatocyte nodules were chemically induced in Fischer 344, DPPIV(+) rats; livers were then perfused and larger (>5 mm) nodules were separated from surrounding tissue. Cells isolated from either tissue were then injected into normal or RS-treated DPPIV(-) recipients. One month after transplantation, grossly visible nodules (2--3 mm) were seen in RS-treated recipients transplanted with nodular cells. They grew rapidly, occupying 80--90% of the host liver at 2 months, and progressed to hepatocellular carcinoma within 4 months. By contrast, no liver nodules developed within 6 months when nodular hepatocytes were injected into the liver of recipients not exposed to RS, although small clusters of donor-derived cells were present in these animals. Taken together, these results directly point to a fundamental role played by the host environment in modulating the growth and the progression rate of altered cells during carcinogenesis. In particular, they indicate that conditions associated with growth constraint of the host tissue can drive tumor progression in vivo.

The resistance phenotype in the development and treatment of cancer

Phenotypic resistance, acquired early in carcinogenesis, has an established role in the pathogenesis of cancer in well-characterised experimental systems, and possibly also has a role in the origin of human cancer. It has been suggested that sunlight, an established risk factor for human skin carcinogenesis, is able to induce rare altered cells resistant to toxicity and to favour their clonal expansion via toxic effects exerted on normal keratinocytes. Other major risk factors for human neoplasia, including smoking and ageing, may also act partly through imposition of a constrained growth environment in the target organ to favour the emergence of altered resistant cells. Strategies aimed at counteracting this constrained environment could be effective in attenuating the force that sustains clonal expansion of altered cells.