Can cancer chemotherapy enhance the malignant behaviour of tumours?

Adverse effects of chemoradiotherapy on invasion and metastasis of tumor cells

The phenomenon of enhanced invasion and metastasis of residual tumor cells has been observed in an increasing number of patients receiving chemoradiotherapy recently, and tumor metastasis will undoubtedly limit patient prognosis. However, the key mechanism by which chemoradiotherapy affects the invasion and metastasis of tumor cells remains unclear. Studies have shown that chemoradiotherapy may directly act on tumor cells and alter the tumor microenvironment, or induce cell apoptosis and autophagy to promote tumor cell survival and metastasis. In this review, we summarize the potential mechanisms by which chemoradiotherapy may affect the biological behavior of tumor cells and open up new avenues for reducing tumor recurrence and metastasis after treatment. These insights will improve the efficacy of chemoradiotherapy.

Chemotherapy can promote liver metastasis by enhancing metastatic niche formation in mice

BACKGROUND

Some chemotherapeutic agents have been reported to promote lung metastasis. However, there have been no reports regarding chemotherapy-induced liver metastasis. We hypothesized that chemotherapy might also enhance liver metastasis. The present study aimed to create a chemotherapy-enhanced liver metastasis mouse model and investigate its mechanism.

MATERIALS AND METHODS

Mice were pretreated with cisplatin, vincristine, or saline by intraperitoneal injection. Next, B16F10 mouse melanoma cells and BE(2)-C human neuroblastoma cells were injected into the spleens of C57BL/6 and BALB/c nu/nu mice, respectively, to induce experimental liver metastasis, and the number of liver nodules was determined. We also analyzed the effect of chemotherapy on changes of the liver tissue regarding representative metastasis-promoting factors using real-time quantitative polymerase chain reaction and immunohistochemical and histological analysis.

RESULTS

Cisplatin increased the number of nodules by 4.7-fold in the B16F10 liver metastasis model. Vincristine increased the number of nodules by 3.8-fold in the BE(2)-C liver metastasis model. Cisplatin increased mRNA levels of matrix-metalloproteinase (MMP)-2 and periostin, while vincristine increased MMP-9 and S100A8/9 levels in liver tissues. Cisplatin induced fibrosis, whereas vincristine induced neutrophil recruitment in liver tissues according to histological and immunohistochemical analysis.

CONCLUSIONS

We concluded that cisplatin or vincristine could enhance liver metastasis of mouse melanoma cells or human neuroblastoma cells, respectively. In addition, the mRNA expression of MMP-2 and periostin, or MMP-9 and S100A8/9 is increased by cisplatin or vincristine pretreatment, possibly resulting in fibrosis or neutrophil recruitment, respectively. These niche factors might be associated with increased liver metastasis.

Anxa2 plays a critical role in enhanced invasiveness of the multidrug resistant human breast cancer cells

Multidrug resistance (MDR) is the major cause of failure in cancer chemotherapy. Recent reports even suggest that MDR is associated with elevated invasion and metastasis of tumor cells. In the current study, we used a proteomic approach to identify genes that play an important role in MDR induced cell migration. 2D-PAGE and MALDI-TOF/MS-based proteomics approach were used to separate and identify differentially expressed proteins between MCF-7 and MCF-7/ADR, a p-glycoprotein-overexpressing adriamycin-resistance breast cancer cell line. Annexin a2 (Anxa2) was identified as highly expressed in MCF-7/ADR cells, but not in MCF-7 cells. Small interference RNA-mediated gene suppression demonstrated that Anxa2 was required for enhanced cell proliferation and invasion of the MCF-7/ADR cells. Down-regulation of Anxa2 alone was not sufficient to revert the cell sensitivity to adriamycin, suggesting that Anxa2 was not required for MDR phenotype. Taken together, our results showed that expression of Anxa2 is enhanced when cancer cells, MCF-7, acquired drug resistance and it plays an essential role in MDR-induced tumor invasion.

Alternating electric fields (TTFields) inhibit metastatic spread of solid tumors to the lungs

Tumor treating fields (TTFields) are low intensity, intermediate frequency, alternating electric fields used to treat cancerous tumors. This novel treatment modality effectively inhibits the growth of solid tumors in vivo and has shown promise in pilot clinical trials in patients with advanced stage solid tumors. TTFields were tested for their potential to inhibit metastatic spread of solid tumors to the lungs in two animal models: (1) Mice injected with malignant melanoma cells (B16F10) into the tail vein, (2) New Zealand White rabbits implanted with VX-2 tumors within the kidney capsule. Mice and rabbits were treated using two-directional TTFields at 100–200 kHz. Animals were either monitored for survival, or sacrificed for pathological and histological analysis of the lungs. The total number of lung surface metastases and the absolute weight of the lungs were both significantly lower in TTFields treated mice then in sham control mice. TTFields treated rabbits survived longer than sham control animals. This extension in survival was found to be due to an inhibition of metastatic spread, seeding or growth in the lungs of TTFields treated rabbits compared to controls. Histologically, extensive peri- and intra-tumoral immune cell infiltration was seen in TTFields treated rabbits only. These results raise the possibility that in addition to their proven inhibitory effect on the growth of solid tumors, TTFields may also have clinical benefit in the prevention of metastatic spread from primary tumors.

A new therapy for highly effective tumor eradication using HVJ-E combined with chemotherapy

BACKGROUND

Inactivated HVJ (hemagglutinating virus of Japan; Sendai virus) particles (HVJ envelope vector; HVJ-E can incorporate and deliver plasmid DNA, siRNA, antibody and peptide and anti-cancer drugs to cells both in vitro and in vivo. We attempted to eradicate tumors derived from mouse colon cancer cells, CT26, by combining bleomycin (BLM)-incorporated HVJ-E (HVJ-E/BLM) with cisplatin (CDDP) administration.

METHODS

CT-26 tumor mass was intradermally established in Balb/c mice. HVJ-E/BLM was directly injected into the tumor mass with or without intraperitoneal administration of CDDP. The anti-tumor effect was evaluated by measuring tumor size and cytotoxic T cell activity against CT26. Re-challenge of tumor cells to treated mice was performed 10 days or 8 months after the initial tumor inoculation.

RESULTS

We found that three intratumoral injections of HVJ-E/BLM along with a single intraperitoneal administration of CDDP eradicated CT26 tumors with more than 75% efficiency. When tumor cells were intradermally re-injected on day 10 after the initial tumor inoculation, tumors on both sides disappeared in most of the mice that received the combination therapy of HVJ-E/BLM and CDDP. Eight months after the initial tumor eradication, surviving mice were re-challenged with CT26 cells. The re-challenged tumors were rejected in all of the surviving mice treated with the combination therapy. Cytotoxic T lymphocytes specific for CT26 were generated in these surviving mice.

CONCLUSION

Combination therapy consisting of HVJ-E and chemotherapy completely eradicated the tumor, and generated anti-tumor immunity. The combination therapy could therefore be a promising new strategy for cancer therapy.

Targeted chemotherapy against intraperitoneally disseminated colon carcinoma using a cationized gelatin–conjugated HVJ envelope vector

The hemagglutinating virus of Japan envelope (HVJ-E; Sendai virus) vector derived from inactivated HVJ particles can be used to deliver DNA, proteins, and drugs into cells both in vitro and in vivo. HVJ-E is capable of delivering bleomycin, an anticancer drug, to various cancer cell lines, thereby producing 300-fold greater cytotoxicity than administration of bleomycin alone. In a mouse model of peritoneally disseminated colon cancer, we injected HVJ-E containing the luciferase gene into the peritoneum. Unexpectedly, luciferase gene expression was not observed within the tumor deposits or any organs. However, when combined with cationized gelatin (CG), CG-HVJ-E produced a high level of luciferase gene expression primarily within the tumor deposits. Forty-eight hours after introducing colon cancer cells into the peritoneum of experimental mice, CG-HVJ-E with or without bleomycin was injected into the abdominal cavity. Following six injections of bleomycin-incorporated CG-HVJ-E, complete responses were observed in 40% of the mice examined. All of the mice that received either empty CG-HVJ-E or bleomycin alone died within 40 days of having cancer cells introduced into the peritoneum. When the mice with complete responses were rechallenged with colon cancer cells from the same cell line, no tumors developed. Thus, CG-HVJ-E may suppress peritoneal dissemination of cancer.

Therapeutic potential of mycobacterial cell wall-DNA complexes

Cell wall skeletons isolated from many bacteria have been shown to possess anticancer activity. The anticancer activities of such preparations have been attributed to the activation of immune effector cells and not to a direct effect on cancer cell division. A cell wall extract from Mycobacterium phlei, wherein mycobacterial DNA in the form of short oligonulceotides is preserved to the cell wall, has anticancer activity against a wide range of cancer cells. Mycobacterial cell wall-DNA complexes (MCC) exert their anticancer activity by a dual mechanism of action: an indirect effect via the induction of anticancer cytokines and a direct effect on cancer cell division mediated by the induction of apoptosis. In this review, the immunomodulatory and the pro-apoptotic mechanisms of action of MCC will be explored. The identification of the active component in MCC will be discussed, as well as the composition differences with cell wall skeletons and live mycobacteria. Finally, the use of MCC against bladder and prostate cancers will be discussed and compared to standard therapies, particularly therapy using mycobacteria and mycobacteria-derived products.

Activated leukocyte cell adhesion molecule (ALCAM) and annexin II are involved in the metastatic progression of tumor cells after chemotherapy with Adriamycin

Metastasis frequently occurs during and/or after chemotherapy resulting in failure. This suggests that inadequate chemotherapy promotes the emergence of more malignant tumor cells with metastatic potential. However, it is not determined how chemotherapy could promote the metastatic progression of tumor cells. In this study, we isolated highly metastatic clones from the tumors treated with ADR using an in vivo experimental model, in which non-metastatic tumor cells were inoculated s.c. in mice, treated with or without Adriamycin and then culture lines were re-established from the tumors. Then we isolated cDNAs for activated leukocyte cell adhesion molecule (ALCAM), osteopontin, and annexin II as candidates for metastasis-promoting genes with the use of a PCR-based subtraction method. Further we examined the metastatic potential of transfectants over-expressing ALCAM, osteopontin, or annexin II and combinations of them. Metastasis to the lung was observed in the mice where transfectants over-expressing ALCAM plus annexin II had been inoculated via tail vein. These results suggest that the over-expression of ALCAM and annexin II play a role in the metastatic progression after chemotherapy with ADR.

Cancer cell progression and chemoimmunotherapy--dual effects in the induction of resistance to therapy

To determine whether resistance to chemoimmunotherapy is acquired during therapy, we investigated the effects of chemotherapeutic agents and anti-tumour polysaccharide, lentinan, on the progression of Rous sarcoma virus-induced S908.D2 fibrosarcomas. The chemoimmunotherapy was effective against the parental S908.D2-bearing mice. Nearly all the mice that were treated with cyclophosphamide (CY) and lentinan achieved complete tumour regression. Only a few of the mice that achieved complete regression of the primary tumours showed a recurrence of the tumour in regional lymph nodes. S908.D2-vp.1 was established from metastatic tumours that developed in the regional lymph nodes of parental S908.D2-bearing mice during therapy. S908.D2-vp.2-or vp.3 cells were sequentially derived in a similar way from S908.D2-vp.1-or-vp.2-bearing mice respectively, in which complete tumour regression at each primary site was achieved during therapy. These lines acquired resistance to CY and lentinan and also to 5-fluorouracil (5-FU)/5'-deoxy-5-fluorouracil and lentinan. No significant difference in either the sensitivity to 5-FU or 4-deoxycyclophosphamide in vitro or in the susceptibility to immune effector cells was observed between the parental and progressed lines (S908.D2-vp1 -vp3). There was an increase in the level of prostaglandin E2 (PGE2) in the progressed lines during repeated therapy (parental, 1171 pg ml(-1); vp.1, 2199 pg ml(-1); vp.2, 5500pg ml(-1); vp3, 16187 pg ml(-1)). There was no significant increase in the production of transforming growth factor beta (TGF-beta). The amount of interleukin-2 (IL-2) produced by spleen cells isolated from the S908.D2-vp.2-bearing mice was decreased compared with the amount produced by the parental S908.D2- bearing mice. Furthermore, combination therapy with lentinan and IL-2 achieved complete tumour regression in all the mice transplanted with S908.D2 progressed tumour lines, although IL-2 alone did not show any anti-tumour effects in either the S908.D2 parental or progressed lines. The findings suggest that the reduced production of IL-2 induced an increase in the production of the PGE2 by progressed tumour lines is involved in the acquisition of resistance.

Differences in resistance to 5-fluorouracil as a function of cell cycle delay and not apoptosis

A series of human embryo fibroblasts has previously been shown to display increasing resistance to the antimetabolites methotrexate (MTX) and N-phosphonacetyl-L-aspartate (PALA) with increasing tumorigenicity. This increased resistance was found to be further increased as a result of salvage pathway activity for purine and pyrimidine biosynthesis. A similar pattern of increasing resistance paralleling increasing tumorigenicity has now been shown to occur with 5-fluorouracil (5-FU), which is independent of salvage pathway activity. The KMS normal cell line was found to be more sensitive to 5-FU than either the immortalised KMST or tumorigenic KN-NM cell lines. Immunohistochemical analysis of the three cell lines demonstrated high levels of p53 protein in the KMST and KN-NM cell lines, but undetectable p53 levels in the KMS cell line. From these data it was hypothesised that a difference in p53 function may be causing the difference in the patterns of sensitivity observed in the three cell lines. P53 is now believed to function as a regulator of a G1 to S cell cycle checkpoint and as an inducer of apoptosis following DNA damage to the cell. The differences in sensitivity of the cell lines could not be explained by differences in the levels of apoptosis but could be attributed to differences in cell cycle response. Our evidence suggests that loss of cell cycle control, possibly through loss of p53 function, is an important factor in increasing the drug resistance of fibroblast cell lines.

Intrinsic or acquired drug resistance and metastasis: are they linked phenotypes?

Evidence is reviewed which suggests a linkage may exist between certain forms of de novo or acquired drug resistance and metastasis. This includes the finding that expression of certain dominantly acting mutant oncogenes or tumor suppressor genes, i.e., genes which normally act to "drive" tumor progression and metastasis, can also affect the expression of drug resistance. Moreover, this can be accompanied by altered expression of certain cellular genes thought to be involved in expression of drug resistance. A direct linkage between acquired drug resistance and metastasis would suggest that tumor sublines selected for drug resistance should manifest more aggressive malignant properties than their drug-sensitive counterparts. While this does not appear to be true for drug resistant sublines selected in vitro, indeed such cell lines frequently manifest diminished in vivo tumorigenic and/or metastatic competence, there is some evidence to support such a correlation exists for tumor cell lines that are selected in vivo for drug resistance. Attention is also drawn to the fact that new linkages between metastasis and drug resistance may be uncovered by analyzing the ability of tumor subpopulations to acquire drug resistance after one or several previous exposures to chemotherapeutic drugs, as opposed to examining intrinsic drug resistance only. Furthermore, ability to detect induced or acquired drug resistance in vitro may be strongly influenced by the types of assay used to detect and monitor drug resistance. In particular, three-dimensional cell culture systems may reveal acquired or induced "multicellular" drug resistance in situations where conventional two-dimensional culture systems do not. Use of three-dimensional culture systems may therefore reveal as yet undiscovered associations between the phenotypes of metastasis and drug resistance.

Antimetabolite-induced increases in the invasive capacity of murine leukaemia L1210 cells

Pretreatment of murine leukaemia L1210 cells with non-lethal concentrations of various antimetabolites increased the in vitro invasive capacity of these cells into monolayers of rat embryo fibroblasts. The increase in invasive capacity was partly correlated with the induced cell cycle arrest. The concomitant increase in cell surface fucosylation and inhibition of invasion with sulphate indicate a role for glycoproteins in this process. Our results suggest that treatment with antimetabolites may lead to a more aggressive phenotype by altering cell surface properties.

Goals of palliative cancer therapy: scope of the problem

This article describes some of the problems of palliative cancer therapy and proposes possible solutions. The topics discussed include the reasons for death in cancer patients, the definition of intermediate and indirect as opposed to direct and measurable goals of treatment, the insufficient outcomes of palliative therapies and the problems associated with the separation of palliative treatment and palliative care. As a solution to these problems, a concept of Tumor versus Host Disease (TvHD) is discussed, and different end points for palliation are defined for daily oncology practice and oncology research. Finally, a way to collect data outside randomized trials is proposed, and the need for data collection is emphasized.

Response of a multidrug-resistant human small-cell lung cancer xenograft to chemotherapy

Small-cell lung carcinomas (SCLC) are highly responsive to various chemotherapies. However only a minority of patients benefit from long survival. SCLC patients treated at the Institut Gustave Roussy received a combined chemotherapy (CCAV) including cisplatin, cyclophosphamide (Cpa), Adriamycin (doxorubicin; Adm) and vepeside (VP16). We report here the intrinsic sensitivity of a small-cell lung carcinoma, designated SCLC-6, grafted in nude mice. This xenografted tumour was derived from an untreated patient. The CCAV regimen given to the patient donor of the tumour sample resulted in a complete response followed by recurrence and death, 8 months after the initial cure. The expression of P-glycoprotein encoded by the MDR1 gene was detected with the C219 antibody on the membrane of SCLC-6 tumour cells. When given to SCLC-6-tumour-bearing nude mice, CCAV induced a strong inhibition of tumour growth (84% of growth inhibition, 20 days after start of the treatment), but no cure. Intensification of CCAV doses did not improve the response. The efficacy of individual agents of the CCAV, given at maximal tolerated doses was analysed. Only cisplatin (10 mg/kg) and Cpa (3 x 50 mg/kg) inhibited SCLC-6 growth (79% and 100% inhibition respectively), VP16 (3 x 24 mg/kg) was poorly efficient (42%) and Adm (10 mg/kg) not at all. Two-drug combinations such as cisplatin plus VP16 or cisplatin plus Cpa inhibited tumour growth (81% and 70%, respectively). Curiously, the efficacy of Cpa, given in combination with cisplatin was less than that of Cpa alone. Repeated treatments with CCAV administered to mice at each in vivo passage of the tumour induced a loss of chemosensitivity, which was observed until the ninth passage. An improvement of the therapeutic response was obtained by adding a headline reverser of multi-drug resistance, verapamil (25 mg/kg), to CCAV (81% versus 63% inhibition). MDR1-related resistance appeared to play a role in the failure of SCLC-6 chemotherapy; frequent recurrences after treatment with cisplatin and Cpa, two drugs that are not recognized by the P-glycoprotein, indicated that other modes of resistance were simultaneously active.

Chemotherapy of advanced epithelial cancer--a critical review

This article is a short version of a report which presents a comprehensive analysis of clinical trials and publications examining the value of cytotoxic chemotherapy in the treatment of advanced epithelial cancer. As a result of the analysis and the comments received from hundreds of oncologists in reply to a request for information, the following facts can be noted. Apart from lung cancer, in particular small-cell lung cancer, there is no direct evidence that chemotherapy prolongs survival in patients with advanced carcinoma. Except for ovarian cancer, available indirect evidence rather supports the absence of a positive effect. In treatment of lung cancer and ovarian cancer, the therapeutical benefit is at best rather small, and a less aggressive treatment seems to be at least as effective as the usual one. It is possible that certain sub-groups of patients benefit from the treatment, yet so far the available results do not allow a sufficiently precise definition of these groups. Many oncologists take it for granted that response to therapy prolongs survival, an opinion which is based on a fallacy and which is not supported by clinical studies. To date, it is unclear whether the treated patients, as a whole, benefit from chemotherapy as to their quality of life. For most cancer sites, urgently required types of studies such as randomized de-escalations of dose or comparisons of immediate versus deferred chemotherapy are still lacking. With few exceptions, there is no good scientific basis for the application of chemotherapy in symptom-free patients with advanced epithelial malignancy.

Drug-target interactions: only the first step in the commitment to a programmed cell death?

The search for novel antitumour drugs has reached a plateau phase. The carcinomas remain almost as intractable as they did 40 years ago and the need for effective therapy is pressing. There is an argument that the current pharmacopoeia is sufficient but, to be effective, the biochemical mechanisms of drug resistance must be circumvented. In tackling the question of why certain cancer cells are resistant, the converse question of why others are sensitive still remains to be answered fully. Asking the fundamental question of why and how a cell dies may provide clues as to what avenues lie open for improved chemotherapy. In this review we survey the recent literature on cell death and we argue that it is possible that the outcome of chemotherapy may be determined by the response of the cell to the formation of the drug-target complex, and/or its sequellae, rather than to the biochemical changes brought about by the drug alone. One of these responses, determined by the phenotype of the cell, may be activation of a genetic programme for cell death.

Radiation enhancement of metastasis: a review

Virtually every modality employed in the treatment of cancer has demonstrated an adverse effect upon metastasis under some conditions. This review surveys the experimental and clinical literature pertaining to the untoward effects of ionizing radiation upon metastatic processes. Two processes are described: (1) enhancement of metastases following local tumor irradiation; (2) localization of metastasis in previously irradiated normal tissues. In the first process the experimental evidence indicates a local effect of irradiation upon the tumor-stroma interface. It predominates under conditions of non-curative radiation doses. There is no proof that this process occurs in clinical practice, but a review of data provides suggestive evidence for its existence following non-curative therapy. The second process is documented both experimentally and clinically. It requires the presence of viable, circulating tumor cells and appears mediated through vascular damage. The few clinical reports suggest that this effect is rare in practice. The clinical significance of both processes appears small under conditions of effective tumor therapy, but it is speculated that inadequate tumor irradiation, or irradiation of normal tissues with uncontrolled tumor elsewhere, may be deleterious.

Use of the Membrane Invasion Culture System (MICS) as a screen for anti-invasive agents

The Membrane Invasion Culture System (MICS) assay was adapted for relatively rapid screening of compounds and used to identify anti-invasive drugs that inhibit human and murine tumor cell migration through a reconstituted basement membrane in vitro. Cell lines demonstrating low and high invasive and metastatic potentials were tested with all compounds for tumoricidal effects prior to evaluation in MICS at non-cytotoxic doses. The effect on invasive potential in the MICS assay was determined in 3 categories: (1) 48 hr drug pre-treatment prior to seeding in the MICS (exceptions: 90 min pre-treatment with pertussis toxin and, for some studies, continuous exposure for 2-7 days); (2) peptide or prostaglandins 2 hr after seeding and attachment to the membranes in MICS followed by continuous exposure; and (3) cells receiving neither drug nor peptide treatment and serving as controls in each MICS chamber. Since invasion involves cellular motility and deformability, some cytoskeleton disrupting agents were selected. Of these, vincristine, colcemid and colchicine inhibited invasion but taxol did not. Pre-treatment with cAMP agonists produced conflicting results: dibutyryl cAMP and 8-(4-chloro-phenylthio) cAMP resulted in 50% and 38% reduction in invasion, respectively, whereas 8-bromo cAMP stimulated invasive potential by 30%. Forskolin and cholera toxin both significantly reduced invasiveness. Pre-treatment with 5-azacytidine and araC, to consider the role of methylation and proliferations decreased invasive ability. Anti-metastatic drugs such as gamma-interferon and razoxane inhibited invasive potential but to varying degrees. Treatment of cells with prostaglandins E2, F2 alpha, A2, and D2 were ineffectual; however, indomethacin mildly inhibits invasion (less than 30%).(ABSTRACT TRUNCATED AT 250 WORDS)

Prospects for the treatment of B cell tumors using idiotypic vaccination

Manipulation of the immune system in order specifically to attack autologous tumor cell has been a distant goal, largely due to the poor definition of tumor-associated antigens. By focussing on B cell lymphomas which express a molecularly defined clonal marker, the idiotypic immunoglobulin, it has been possible to generate autologous anti-idiotypic responses which suppress individual tumors. Studies of the components of these responses are providing insight into host effector mechanisms which can be activated against tumors, and also into the many strategies adopted by the target cells in order to avoid such attack. Promising results in various animal models where tumor bearers can be treated by idiotypic immunization have led to the point where application of this approach to the treatment of certain categories of human B cell lymphoma can be considered.