Deciphering biological characteristics of tumorigenic subpopulations in human colorectal cancer reveals cellular plasticity

Vactosertib potently improves anti-tumor properties of 5-FU for colon cancer

BACKGROUND

Several studies have shown that the TGF-β signaling pathway plays a critical role in colorectal cancer (CRC) pathogenesis. The aim of the current study is to investigate the therapeutic potential of Vactosertib (EW-7197), a selective inhibitor of TGF-β receptor type I, either alone or in combination with the standard first-line chemotherapeutic treatment, 5-Fluorouracil (5-FU), in CRC progression in both cellular and animal models.

METHODS

Real-Time PCR, Zymography, enzyme-linked immunosorbent assay (ELISA), Hematoxylin and Eosin (H&E) tissue staining, and Flow cytometry techniques were applied to determine the anti-tumor properties of this novel TGF-β inhibitor in in vitro (CT-26 cell line) and in vivo (inbred BALB/C mice) samples.

RESULTS

Our findings showed that Vactosertib decreased cell proliferation and induced spheroid shrinkage. Moreover, this inhibitor suppressed the cell cycle and its administration either alone or in combination with 5-FU induced apoptosis by regulating the expression of p53 and BAX proteins. It also improved 5-FU anti-cancer effects by decreasing the tumor volume and weight, increasing tumor necrosis, and regulating tumor fibrosis and inflammation in an animal model. Vactosertib also enhanced the inhibitory effect of 5-FU on invasive behavior of CRC cells by upregulating the expression of E-cadherin and inhibiting MMP-9 enzymatic activity.

CONCLUSION

This study demonstrating the potent anti-tumor effects of Vactosertib against CRC progression. Our results clearly suggest that this inhibitor could be a promising agent reducing CRC tumor progression when administered either alone or in combination with standard treatment in CRC patients.

Suspension culture strategies to enrich colon cancer stem cells

How to efficiently obtain high-purity cancer stem cells (CSCs) has been the basis of CSC research, but the optimal conditions for serum-free suspension culture of CSCs are still unclear. The present study aimed to define the optimal culture medium composition and culture time for the enrichment of colon CSCs via suspension culture. Suspension cell cultures of colon cancer DLD-1 cells were prepared using serum-free medium (SFM) containing variable concentrations of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) to produce spheroids. Culture times were set at 10, 20 and 30 days. A total of nine different concentrations of EGF and bFGF were added to SFM to generate nine experimental groups. The proportions of CD44⁺, CD133⁺, and CD44⁺CD133⁺ double-positive spheroid cells were detected via flow cytometry. mRNA expression of stemness-, epithelial-mesenchymal transition- and Wnt/β-catenin pathway-associated genes was determined via reverse transcription-quantitative PCR. Self-renewal ability was evaluated by a sphere-forming assay. Tumorigenesis was studied in vitro using a colony formation assay and in vivo via subcutaneous cell injection in nude mice. It was found that the highest expression proportions of CD133⁺ and CD44⁺ spheroid cells were observed in group (G)9 (20 ng/ml EGF + 20 ng/ml bFGF) at 30 days (F=123.554 and 99.528, respectively, P<0.001), CD133⁺CD44⁺ cells were also observed in G9 at 30 days (and at 10 days in G3 and 20 days in G6; F=57.897, P<0.001). G9 at 30 days also displayed the highest expression of Krüppel-like factor 4, leucine-rich repeat-containing G protein-coupled receptor 5, CD44, CD133, Vimentin and Wnt-3a (F=22.682, 25.401, 3.272, 7.852, 13.331 and 17.445, respectively, P<0.001) and the lowest expression of E-cadherin (F=10.851, P<0.001). G9 at 30 days produced the highest yield of cell spheroids, as determined by a sphere forming assay (F=19.147, P<0.001); colony formation assays also exhibited the greatest number of colonies derived from G9 spheroids at 30 days (F=60.767, P<0.01), which also generated the largest mean tumor volume in the subcutaneous tumorigenesis xenograft model (F=12.539, P<0.01). In conclusion, 20 ng/ml EGF + 20 ng/ml bFGF effectively enriched colon CSCs when added to suspension culture for 30 days, and conferred the highest efficiency compared with other combinations.

ARRB2 promotes colorectal cancer growth through triggering WTAP

Colorectal cancer (CRC) is one of the most lethal cancers worldwide. The expression of β-arrestin2 (β-Arr2, ARRB2) in CRC has been well investigated; however, its exact mechanism causing the cancer progression remains unclear. In this study, we discovered that the expression level of ARRB2 was significantly upregulated in CRC as compared to the normal tissues by employing the Cancer Genome Atlas (TCGA) data, western blot analysis, and immunohistochemistry. Furthermore, the level of ARRB2 was correlated with the patients' overall survival by Kaplan-Meier analysis. The higher expression of ARRB2 promoted CRC cell growth, enhanced the cell motility, and blocked cell apoptosis, which is crucial for tumor growth. Lastly, the suppression of ARRB2 expression was enough to attenuate the progression of CRC induced by azoxymethane/dextran sodium sulfate. Interestingly, we also found that the knockdown of ARRB2 decreased several cancer pathways mediated by the expression of Wilms tumor 1 associated protein (WTAP), which led to the inhibition of cell proliferation and migration. Altogether, our results demonstrated that ARRB2 promoted the growth and migration of CRC cells by regulating the WTAP expression.

The role of melatonin in colorectal cancer treatment: a comprehensive review

Colorectal cancer (CRC) is one of the most common types of cancer worldwide, known as the second leading cause of cancer-related deaths annually. Currently, multimodal treatment strategies, including surgical resection, combined with chemotherapy and radiotherapy, have been used as conventional treatments in patients with CRC. However, clinical outcome of advanced stage disease remains relatively discouraging, due mainly to appearance of CRC chemoresistance, toxicity, and other detrimental side effects. New strategies to overcome these limitations are essential. During the last decades, melatonin (MLT) has been shown to be a potent antiproliferative, anti-metastatic agent with cytotoxic effects on different types of human malignancies, including CRC. Hence, this comprehensive review compiles the available experimental and clinical data analyzing the effects of MLT treatment in CRC patients and its underlying molecular mechanisms.

Antitumor efficacy of cytosine deaminase-armed vaccinia virus plus 5-fluorocytosine in colorectal cancers

Background

Vaccinia viruses have emerged as attractive therapeutic candidates for cancer treatment due to their inherent ability of tumor tropism and oncolytic property. Cytosine deaminase (CD), which is derived from bacteria or yeast, can convert a relatively nontoxic prodrug 5-fluorocytosine (5-FC) into the active anticancer drug 5-Fluorouracil (5-FU). Vaccinia virus armed with the prodrug-activator CD gene would result in augmented antitumor effects that combined the effect of vaccinia virus and 5-FU together, and particularly limited the anticancer drug to tumor regions.

Methods

The attenuated vaccinia Tian Tan strain Guang 9 (VG9), with active yeast CD expression and thymidine kinase (TK) deficiency, was successfully constructed. Then, in vitro and in vivo antitumor efficacy of vaccinia VG9-CD plus 5-FC administration was evaluated in colorectal cancer cells.

Results

Vaccinia viruses displayed different oncolytic potency in vitro cells, no relationship with whether they were cancer cells or normal cells. In colorectal tumor models, mice treated with vaccinia VG9-TK^- showed better tumor remission ability and prolonged survival. Moreover, vaccinia VG9-CD in combination with gavage administration of 5-FC displayed the best antitumor efficacy, especially for the prolongation of survival.

Conclusions

Vaccinia VG9-CD in combination with 5-FC plays combined effect of vaccinia virus and chemotherapy, and becomes a promising virotherapy for cancer.

The fiber metabolite butyrate reduces gp130 by targeting TRAF5 in colorectal cancer cells

Background

Dietary fiber is effective for colorectal cancer (CRC) treatment. Interleukin-6 (IL-6) and its adaptors are potential targets for CRC therapy. Butyrate, a metabolite of dietary fiber, is a new, highly safe type of targeted drug.

Methods

In this study, Cell Counting Kit-8 cell viability and wound healing assays, western blot analysis, immunofluorescence staining, and xenograft tumor mouse models were used to evaluate the anticancer effect of butyrate and its possible mechanism in vivo and in vitro.

Results

Dietary fiber and sodium butyrate (NaB) decreased CRC burden by decreasing IL-6 receptor gp130 and blocking IL-6/JAK2/STAT3 axis activation in vitro and in vivo. Furthermore, NaB reduced the gp130 protein level by regulating its degradation rate via targeting TRAF5.

Conclusions

The fiber metabolite butyrate inhibits CRC development by reducing gp130 via TRAF5.

Cancer Stem Cells and Combination Therapies to Eradicate Them

Cancer stem cells (CSCs) show self-renewal ability and multipotential differentiation, like normal stem or progenitor cells, and which proliferate uncontrollably and can escape the effects of drugs and phagocytosis by immune cells. Traditional monotherapies, such as surgical resection, radiotherapy and chemotherapy, cannot eradicate CSCs, however, combination therapy may be more effective at eliminating CSCs. The present review summarizes the characteristics of CSCs and several promising combination therapies to eradicate them.

Cancer stem cells as therapeutic targets of pancreatic cancer

The discovery of stem cells and their potential abilities in self-renewal and differentiation has opened a new horizon in medicine. Scientists have found a small population of stem cells in some types of cancers with the same functions as normal stem cells. There are two models for tumor progression: clonal (stochastic) and cancer stem cell (CSCs) models. According to the first model, all transformed cells in the tumor have carcinogenic potential and are able to proliferate and produce the same cells. The latter model, which has received more attention recently, considers the role of CSCs in drug resistance and tumor metastasis. Following the model, researchers have found that targeting CSCs may be a promising way in cancer therapy. This review describes CSC characteristics in general, while also focusing on CSC properties in the context of pancreatic cancer.

Conversion to resectability using transcatheter arterial chemoembolization alternating with mFOLFOX6 in patients with colorectal liver metastases

Background:

Colorectal cancer is one of the most common malignancies in the world, and about 25% of colorectal cancer patients present with colorectal cancer liver metastases (CRCLM) even at new diagnosis. The study was to evaluate the safety and efficacy of transcatheter arterial chemoembolization (TACE) alternating with mFOLFOX6 in Chinese patients with unresectable CRCLM.

Materials and Methods:

In this study, by combining the systemic and regional treatment, the resectability rate, overall survival, and progression-free survival were measured with addition of TACE. Included patients had Eastern Cooperative Oncology Group performance status 0–2. Sixty-two patients received mFOLFOX6 plus one TACE after 2 weeks of chemotherapy; after 2 weeks, the next periodical treatment repeated. Patients received operation when the liver metastases were converted to resectability or severe tumor-associated complications occurred.

Results:

We found that 28 patients (45.2%) patients received operation after the treatment of TACE combined with systemic chemotherapy. The median time from initial treatment to the operation was 6 months. The median follow-up period was 41 months in all the patients. The 3-year survival rate of resected patients and unresected patients was 54% and 17%, respectively. Post-TACE syndrome was the major adverse reaction (81%). Other adverse reactions were neutropenia, nausea, and neurotoxicity. No patient died of the adverse reactions. The resection rate was related to hepatic segments and vasculature involvement.

Conclusion:

Taken together, TACE alternating with mFOLFOX6 has been proved to be safe and effective for CRCLM treatment to improve resection rate and prolong the survival time.

Evaluation of antitumor effects of aspirin and LGK974 drugs on cellular signaling pathways, cell cycle and apoptosis in colorectal cancer cell lines compared to oxaliplatin drug

Colorectal cancer (CRC) is one of the most common gastrointestinal malignancies. Despite recent advances in the treatment for CRC, resistance to chemotherapy drugs and recurrence of the tumor are among the main problems for treatment in this cancer. The MTT assay was performed to assess the cytotoxic effects of drugs on CRC cell lines (SW742 and SW480) and normal colon cells. Three-dimensional culture (spheroid) was also used to evaluate the effect of drugs on tumor cell masses. The rate of expression of genes was also evaluated using Real-Time PCR. The analysis of the results demonstrated that aspirin and LGK974 have cytotoxic effects on CRC cell lines, and in the IC50 dose, they disintegrate the cancerous cell masses. These drugs reduce the invasion and increase apoptosis in SW742 and SW480 cell lines. A decrease in the expression of WNT, AXIN, TCF and APC genes and an increase in the expression of β-catenin gene in the WNT signaling pathway were revealed. The genes involved in the MAPK signaling pathway such as ERK, JNK, KRAS and MEK showed a decrease in expression and a increase in expression of RAF gene. In the apoptotic pathway, increased expression of BAX and decreased expression of BCL-2 were reported. Also, decreased expression of P53, cyclin D1 and COX-2 was observed. This study demonstrates that aspirin and LGK974 could be effective in inhibiting the signaling pathways of WNT and MAPK, arresting cell cycle and inducing apoptosis in CRC cell lines.

Knockdown of Sal-like 4 expression by siRNA induces apoptosis in colorectal cancer

Colorectal cancer (CRC) is known as the third most common malignancies among men and women and is also the second leading cause of cancer-related deaths worldwide. It has been indicated that a variety of risk factors are involved in the pathogenesis of CRC. Spalt-like transcription factor 4 (SALL4) is known as a transcription factor that plays an important role in the proliferation of cancerous cells. In this study, using a specific sequence of small interfering RNA (siRNA) against the sequence of SALL4, its activity is investigated in the CRC cell line (sw742). The CRC cells (sw742) were cultured and then, using a specific anti-SALL4 siRNA, their toxic doses were determined. Then, the gene is transfected into the cell. Proliferation and expression of the SALL4 and Bcl-2 gene were measured using the real-time polymerase chain reaction method. Cell death was evaluated by propidium iodide staining and fluorescence-activated cell sorting analysis. Our results indicated that the specific concentration of siRNA of the SALL4 gene was 62.5 nmole. Gene expression of SALL4 and Bcl-2 results showed that expression of Bcl-2 gene in the siRNA group was significantly reduced. In conclusion, our finding indicated that it could be used as a therapeutic and diagnostic biomarker in the treatment of patients with CRC.

Effectiveness of adjuvant chemotherapy in patients with Stage II colorectal cancer: A multicenter retrospective study

Background:

Adjuvant chemotherapy (ACT) for patients with Stage II colorectal cancer (CRC) is an area of controversy in oncology. International guidelines recommend the use of ACT in patients with specific high-risk features. This study aimed to investigate the effectiveness of ACT in improving survival in patients with and without high-risk features.

Materials and Methods:

A total of 225 patients with Stage II CRC who underwent primary tumor resection were included in this study. Patients with one or more high-risk features including T4 tumor, poor differentiation, lymphovascular invasion, perineural invasion, bowel obstruction, local perforation, positive resection margins, or suboptimal lymph node sampling (fewer than 12 nodes) were classified as high risk. The survival analysis was performed between patients who only received curative surgery and those received single-agent (5-fluorouracil [5-FU] and leucovorin [LV] or capecitabine) or multiagent ACT (oxaliplatin and 5-FU + LV or oxaliplatin and capecitabine).

Results:

The 5-year overall survival (OS) rate was 88.4%, and the 5-year disease-free survival (DFS) rate was 80.4%. The 5-year OS and DFS rates improved insignificantly with ACT (89.8% vs. 81.2%, P = 0.59 and 81.3% vs. 74.6%, P = 0.41, respectively); however, multiagent ACT results to inferior 5-year OS and DFS compared to single-agent ACT (82.1 vs. 92.8%, P = 0.14 and 70.1% vs. 86%, P = 0.07, respectively). ACT was associated with insignificant improved OS and DFS in both high-risk and low-risk groups, but high-risk patients who received multiagent ACT had a significant inferior OS and DFS in comparison with those received single-agent ACT. T4 tumor and obstruction were independent poor prognostic factors affecting OS and DFS.

Conclusion:

In our population, the improvement of OS and DFS with ACT was not statistically significant in high-risk and low-risk patients with Stage II CRC.

Vaccines for colorectal cancer: an update

Colorectal cancer (CRC) is known as the third most common and fourth leading cancer associated death worldwide. The occurrence of metastasis has remained as a critical challenge in CRC, so that distant metastasis (mostly to the liver) has been manifested in about 20%-25% of patients. Several screening approaches have introduced for detecting CRC in different stages particularly in early stages. The standard treatments for CRC are surgery, chemotherapy and radiotherapy, in alone or combination. Immunotherapy is a set of novel approaches with the aim of remodeling the immune system battle with metastatic cancer cells, such as immunomodulatory monoclonal antibodies (immune checkpoint inhibitors), adoptive cell transfer (ACT) and cancer vaccine. Cancer vaccines are designed to trigger the intense response of immune system to tumor-specific antigens. In two last decades, introduction of new cancer vaccines and designing several clinical trials with vaccine therapy, have been taken into consideration in colon cancer patients. This review will describe the treatment approaches with the special attention to vaccines applied to treat colorectal cancer.

MicroRNA: A new player in response to therapy for colorectal cancer

Colorectal cancer (CRC) is one of the important malignancies that result in cancer-related deaths worldwide. Multiple lines of evidence have indicated that different responses to therapy in CRC cells led to the failure of the current therapies. Hence, identification of the underlying cellular and molecular pathways involved in the emergence of different responses from CRC cells could contribute to finding and designing new therapeutic platforms to overcome the present limitations. Among the various targets involved in CRC pathogenesis, microRNAs (miRNAs) have key roles in many signaling pathways that are associated with the initiation and progression of CRC. Increasing evidence has confirmed that miRNAs as epigenetic regulators could play critical roles in the response (resistance or sensitivity) to therapy. Cancer stem cells are well-known players in resistance to therapy in CRC. They have been shown to play significant roles via inhibition and activation of many miRNA networks. Hence, miRNAs could be involved in the resistance and sensitivity of therapy in CRC cells via affecting different mechanisms, such as activation of cancer stem cells. Here, we summarized the role of various miRNAs in response to therapy of CRC cells. Moreover, we highlighted the roles of these molecules in the function of cancer stem cells, which are known as important players in the resistance to therapy in CRC.

Cancer trends in a province of Southwest of Iran, 2003-2016

Background:

Awareness of the trends of cancer incidence in each geographic region is an important. The aim of present study was to determine the incidence trends of cancer in Chaharmahal and Bakhtiari (Ch and B) province in Southwest of Iran.

Materials and Methods:

In this secondary data analysis, retrospective existing data were used from cancer registry reports in Ch and B in Southwest of Iran in 2003–2016. Data on epidemiologic trend were analyzed using Joinpoint software package and annual percentage change (APC) with 95% confidence interval (95% CI) was computed.

Results:

Age-standardized incidence rate per 100,000 persons in the province in 2003 was 31.74 that increased to 147.14 in 2016. APC during 2003–2016 was 12.58% (CI: 9.3–16) and significant, which was 10.22% (7.4–13.1) and 14.47% (10.2–18.9) in men and women, respectively. Incidence of the stomach, breast, colorectal, thyroid, lymph node, and ovarian cancers is increasing and the highest incidence was observed in two age groups of 25–34 and 55–64 years.

Conclusion:

In general, cancers are of increasing trend. Surveillance and monitoring the incidence of cancer and studying the causes of environmental or genetic in the cancer changes can help for cancer prevention and control.

Strategy to targeting the immune resistance and novel therapy in colorectal cancer

Assessing the CRC subtypes that can predict the outcome of colorectal cancer (CRC) in patients with immunogenicity seems to be a promising strategy to develop new drugs that target the antitumoral immune response. In particular, the disinhibition of the antitumoral T‐cell response by immune checkpoint blockade has shown remarkable therapeutic promise for patients with mismatch repair (MMR) deficient CRC. In this review, the authors provide the update of the molecular features and immunogenicity of CRC, discuss the role of possible predictive biomarkers, illustrate the modern immunotherapeutic approaches, and introduce the most relevant ongoing preclinical study and clinical trials such as the use of the combination therapy with immunotherapy. Furthermore, this work is further to understand the complex interactions between the immune surveillance and develop resistance in tumor cells. As expected, if the promise of these developments is fulfilled, it could develop the effective therapeutic strategies and novel combinations to overcome immune resistance and enhance effector responses, which guide clinicians toward a more “personalized” treatment for advanced CRC patients.

Cancer stem cells in progression of colorectal cancer

Colorectal cancer is one of the most common cancers worldwide with high mortality. Distant metastasis and relapse are major causes of patient death. Cancer stem cells (CSCs) play a critical role in the metastasis and relapse of colorectal cancer. CSCs are a subpopulation of cancer cells with unique properties of self-renewal, infinite division and multi-directional differentiation potential. Colorectal CSCs are defined with a group of cell surface markers, such as CD44, CD133, CD24, EpCAM, LGR5 and ALDH. They are highly tumorigenic, chemoresistant and radioresistant and thus are critical in the metastasis and recurrence of colorectal cancer and disease-free survival. This review article updates the colorectal CSCs with a focus on their role in tumor initiation, progression, drug resistance and tumor relapse.

Design, expression and evaluation of novel chimeric protein constructed from colorectal tumor-associated antigen

There were 134,000 new diagnosis and 49,000 deaths in 2016 due to colorectal cancer. Similar to most cancers, early diagnosis increases the chance of successful treatment. Detection of tumor-associated antigens or the immune response against such markers is one of the most common methods of diagnosis. In that regard, we aimed to design and express a chimeric protein from the most common tumor-associated antigens in colorectal cancer and assess its ability to detect the immune response in comparison with the parental tumor-associated antigens in patient's sera. Through bioinformatics approaches a chimeric protein from carcinoembryonic antigen (CEA) and carbohydrate antigen 19.9 (CA19-9) was designed and expressed in E. coli (BL21DE3). Proper folding, expression levels and immune reactivity were assessed by western blot, ELISA and immunohistochemistry. Recombinant proteins functionality and immune reactivity were confirmed by ELISA and Western blot. Results showed that recombinant CEA, recombinant CA19.9 and chimeric protein of CEA- CA19.9 have strong reactivity with antibodies in the sera of colorectal cancer patients, whereas no reactivity was seen with the sera of healthy volunteers. Significantly stronger immune reactivity was seen with the chimeric protein than each of the CEA or CA19.9 alone. Overall, it was concluded that the designed recombinant proteins in this study could be used to detect autoantibodies produced against the colorectal tumor-associated antigens. The chimeric CEA-CA19.9 protein shows a stronger reactivity with the sera antibodies of colorectal cancer patients that CEA or CA19.9 alone.

MiR-21: A key player in glioblastoma pathogenesis

Glioblastoma multiform (GBM) is one of common cancers worldwide which has high rate among various populations. Despite serious efforts worldwide, GBM remains a deadly disease which is associated with poor prognosis. Multiple lines evidence indicated that deregulation of a variety of cellular and molecular pathways are related with GBM pathogenesis. Among of various targets involved in GBM pathogenesis, microRNAs (miRNAs) have been emerged as targets which deregulation of them are related with various stages of GBM. These molecules are small non-coding RNAs which could affect on a variety of cellular and molecular pathways involved in GBM. It has been showed that deregulation of them are associated with initiation and progression of GBM. MiR-21 is one of important miRNAs involved in GBM pathogenesis. A large number studies indicated that this miRNA could affect on a variety of cellular and molecular pathways such as insulin-like growth factor (IGF)-binding protein-3 (IGFBP3), RECK, and TIMP3. Exosomes are one of important players in GBM pathogenesis. Among of various exosomes, exosomal miR-21 may has key roles in GBM pathogenesis. These findings indicated that miR-21 has critical roles in GBM pathogenesis and could be used as diagnostic and therapeutic biomarkers for GBM patients. Here, we summarized the roles of miR-21 and exosomal miR-21 in GBM pathogenesis. Moreover, we highlighted utilization of miR-21 as diagnostic and therapeutic biomarker for GBM patients.

Targeting RAS signaling pathway as a potential therapeutic target in the treatment of colorectal cancer

The V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) is frequently dysregulated in colorectal cancer (CRC). It is involved in the modulation of several downstream effectors, that include: Raf/Mek/Erk, PI3K/Akt, RalGDS/p38MAPK, and Rac/Rho, and thereby influences tumorigenesis, the invasive behaviors of tumor cell, and resistance to therapy. There is growing evidence exploring the use of drugs that target these pathways in the treatment of CRC. Cetuximab has been approved for CRC patients without a KRAS mutation, or for EGFR-expressing metastatic CRC, although some of the patients have a mutation of KRAS and NRAS. This review summarizes the recent knowledge about the therapeutic potential of targeting RAS with particular emphasis on recent preclinical and clinical studies in treatment of CRC.

Molecular imaging and cancer gene therapy

Gene therapy is known as one of the most advanced approaches for therapeutic prospects ranging from tackling genetic diseases to combating cancer. In this approach, different viral and nonviral vector systems such as retrovirus, lentivirus, plasmid and transposon have been designed and employed. These vector systems are designed to target different therapeutic genes in various tissues and cells such as tumor cells. Therefore, detection of the vectors containing therapeutic genes and monitoring of response to the treatment are the main issues that are commonly faced by researchers. Imaging techniques have been critical in guiding physicians in the more accurate and precise diagnosis and monitoring of cancer patients in different phases of malignancies. Imaging techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are non-invasive and powerful tools for monitoring of the distribution of transgene expression over time and assessing patients who have received therapeutic genes. Here, we discuss most recent advances in cancer gene therapy and molecular approaches as well as imaging techniques that are utilized to detect cancer gene therapeutics and to monitor the patients' response to these therapies worldwide, particularly in Iranian Academic Medical Centers and Hospitals.Cancer Gene Therapy advance online publication, 18 November 2016; doi:10.1038/cgt.2016.62.