Targeting Acid Ceramidase to Improve the Radiosensitivity of Rectal Cancer.

Previous work utilizing proteomic and immunohistochemical analyses has identified that high levels of acid ceramidase (AC) expression confers a poorer response to neoadjuvant treatment in locally advanced rectal cancer. We aimed to assess the radiosensitising effect of biological and pharmacological manipulation of AC and elucidate the underlying mechanism. AC manipulation in three colorectal cancer cell lines (HT29, HCT116 and LIM1215) was achieved using siRNA and plasmid overexpression. Carmofur and a novel small molecular inhibitor (LCL521) were used as pharmacological AC inhibitors. Using clonogenic assays, we demonstrate that an siRNA knockdown of AC enhanced X-ray radiosensitivity across all colorectal cancer cell lines compared to a non-targeting control siRNA, and conversely, AC protein overexpression increased radioresistance. Using CRISPR gene editing, we also generated AC knockout HCT116 cells that were significantly more radiosensitive compared to AC-expressing cells. Similarly, two patient-derived organoid models containing relatively low AC expression were found to be comparatively more radiosensitive than three other models containing higher levels of AC. Additionally, AC inhibition using carmofur and LCL521 in three colorectal cancer cell lines increased cellular radiosensitivity. Decreased AC protein led to significant poly-ADP ribose polymerase-1 (PARP-1) cleavage and apoptosis post-irradiation, which was shown to be executed through a p53-dependent process. Our study demonstrates that expression of AC within colorectal cancer cell lines modulates the cellular response to radiation, and particularly that AC inhibition leads to significantly enhanced radiosensitivity through an elevation in apoptosis. This work further solidifies AC as a target for improving radiotherapy treatment of locally advanced rectal cancer.

Multicenter, Randomized, Phase III Trial of Neoadjuvant Chemoradiation With Capecitabine and Irinotecan Guided by UGT1A1 Status in Patients With Locally Advanced Rectal Cancer.

PURPOSE: Differentiating the irinotecan dose on the basis of the uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) genotype improves the pathologic complete response (pCR) rate. In this study, we further investigated preoperative irinotecan combined with capecitabine-based chemoradiotherapy for locally advanced rectal cancer. PATIENTS AND METHODS: We conducted this randomized, open-label, multicenter, phase III trial in China. Eligible patients with clinical T3-4 and/or N+ rectal adenocarcinoma, UGT1A1 genotype *1*1 or *1*28 were randomly allocated to the control group: pelvic radiation of 50 Gy/25 fractions with concurrent capecitabine, followed by oxaliplatin and capecitabine; or the experimental group: radiation with capecitabine combined with weekly irinotecan 80 mg/m2 for patients with UGT1A1*1*1 or 65 mg/m2 for patients with UGT1A1*1*28, followed by irinotecan and capecitabine. The primary end point was pCR. This trial was registered with ClinicalTrials.gov (ClinicalTrials.gov identifier: NCT02605265). RESULTS: Of the 360 patients initially enrolled, 356 were evaluated as the modified intention-to-treat population (n = 178 in both groups). Surgery was performed in 87% and 88% of patients in the control and experimental groups, respectively. The pCR rates were 15% (n = 27 of 178) and 30% (n = 53 of 178) in the control and experimental groups (risk ratio, 1.96; 95% CI, 1.30 to 2.97; P = .001). Four and 6 patients achieved complete clinical response in the control and experimental groups, respectively. Grade 3-4 toxicities were recorded in 11 (6%) and 68 (38%) patients in the control and experimental groups, respectively (P < .001). The commonest grade 3-4 toxicities were leukopenia, neutropenia, and diarrhea. The overall surgical complication rate was not significantly different between the two groups (11% v 15%; P < .001). CONCLUSION: Adding irinotecan guided by UGT1A1 genotype to capecitabine-based neoadjuvant chemoradiotherapy significantly increased complete tumor response in Chinese patients.

Serum chitinase activity prognosticates metastasis of colorectal cancer.

BACKGROUND: This study aimed to evaluate the value of chitinase activity in prognosticating the occurrence of metastasis in and prognosis of patients with colorectal cancer (CRC). METHODS: The chitinase activity in four different groups, namely 335 CRC patients without distant metastasis at their first visit (Group 1), 51 patients with CRC having synchronous liver metastasis (Group 2), 100 healthy age-matched controls (Group 3) and 40 patients with liver cancer (Group 4), were assayed using an enzyme-linked immunosorbent assay. The Cox proportional hazards ratio model and Kaplan-Meier curve were used to identify the association between chitinase activity and the clinical outcome of CRC patients without metastasis in the training set and testing set at their first visit. An in vitro Transwell experiment was performed to evaluate the migration of colon cancer cells. RESULTS: Patients with high chitinase activity had a significantly higher metastasis risk than those with low chitinase activity in the training and testing sets during follow-up, both at stage I/II and stage III. Further, multivariate analysis revealed that chitinase activity was an independent risk factor prognosticating liver metastases (P = 0.001). The combination of chitinase activity and lymph node metastasis status increased the accuracy of the prognosis of liver metastases after radical resection (P = 0.454E-011). In addition, chitinase promoted CRC cell migration in vitro. CONCLUSIONS: Chitinase activity can prognosticate the occurrence of metastasis in patients with CRC. Moreover, the combination of chitinase activity and N stage increased the power of prognosticating the occurrence of metastasis. Inhibiting chitinase activity may serve as a new strategy to treat metastases of CRC.

HER2 status in patients with residual rectal cancer after preoperative chemoradiotherapy: the relationship with molecular results and clinicopathologic features.

The specific role of human epidermal growth factor receptor-2 (HER2) status in rectal cancers remains unclear. This study therefore aimed to explore clinicopathologic and molecular characteristics, and prognostic value of HER2-positivity in residual mid- and/or low-rectal cancers after preoperative chemoradiotherapy (CRT). Surgical specimens from 145 patients with residual rectal cancer after preoperative CRT between January 2006 and January 2011 were used to evaluate HER2 status. HER2 protein expression and gene amplification were determined using immunohistochemistry (IHC) and silver in situ hybridization (SISH) on whole tissue sections, respectively. Polymerase chain reaction was used to analyze molecular characteristics, including microsatellite instability (MSI) and mutations in KRAS exon 2 (codon 12 and 13) and BRAF V600E mutation. Of 139 eligible patients, 8 (5.8%) had HER2 overexpression (IHC 2+ and 3+) that was not associated with clinicopathologic characteristics and patient survival, except positive circumferential resection margin (CRM) (P = 0.012). SISH was performed on 24 patient samples with IHC 1+ (n = 16), 2+ (n = 6), and 3+ (n = 2). HER2 amplification was identified in 3 patients (2.2%); however, this was also associated with positive CRM (P = 0.009) but not survival (all P > 0.05). Moreover, HER2 overexpression and amplification had no relationship with KRAS or BRAF mutations, and MSI status (all P > 0.05). HER2 positivity was found in a minority of rectal cancer patients and was not significantly associated with clinicopathologic and molecular characteristics. Our findings can be helpful in understanding the clinicopathologic bases of HER2 status in rectal cancers.

The predictive and prognostic potential of plasma telomerase reverse transcriptase (TERT) RNA in rectal cancer patients.

BACKGROUND: Preoperative chemoradiotherapy (CRT) followed by surgery is the standard care for locally advanced rectal cancer, but tumour response to CRT and disease outcome are variable. The current study aimed to investigate the effectiveness of plasma telomerase reverse transcriptase (TERT) levels in predicting tumour response and clinical outcome. METHODS: 176 rectal cancer patients were included. Plasma samples were collected at baseline (before CRT=T0), 2 weeks after CRT was initiated (T1), post-CRT and before surgery (T2), and 4-8 months after surgery (T3) time points. Plasma TERT mRNA levels and total cell-free RNA were determined using real-time PCR. RESULTS: Plasma levels of TERT were significantly lower at T2 (P<0.0001) in responders than in non-responders. Post-CRT TERT levels and the differences between pre- and post-CRT TERT levels independently predicted tumour response, and the prediction model had an area under curve of 0.80 (95% confidence interval (CI) 0.73-0.87). Multiple analysis demonstrated that patients with detectable TERT levels at T2 and T3 time points had a risk of disease progression 2.13 (95% CI 1.10-4.11)-fold and 4.55 (95% CI 1.48-13.95)-fold higher, respectively, than those with undetectable plasma TERT levels. CONCLUSIONS: Plasma TERT levels are independent markers of tumour response and are prognostic of disease progression in rectal cancer patients who undergo neoadjuvant therapy.

Understanding the role of primary tumour localisation in colorectal cancer treatment and outcomes.

Metastatic colorectal carcinoma (mCRC) is a heterogeneous disease with differing outcomes and clinical responses and poor prognosis. CRCs can be characterised by their primary tumour location within the colon. The left-sided colon, derived from the hindgut, includes the distal third of the transverse colon, splenic flexure, descending colon, sigmoid colon and rectum. The right-sided colon, derived from the midgut, includes the proximal two-thirds of the transverse colon, ascending colon and caecum. Sometimes, the rectum is described separately, despite originating from the hindgut, and in many clinical series, the left-sided colon includes only tumours within and distal to the splenic flexure. Differences in the microbiome, clinical characteristics and chromosomal and molecular characteristics have been reported between the right and left side of the colon, regardless of how this is defined. There is now strong evidence from clinical studies in patients with mCRC for the prognostic effect of primary tumour location. The impact of primary colonic tumour location on response to treatment is now under investigation in a large number of clinical studies in patients with mCRC. In this review, we summarise the microbiome, clinical, chromosomal and molecular differences associated with the primary location of CRC. We present an overview of the proven prognostic impact of primary tumour location for patients with mCRC and discuss emerging data for the predictive impact of primary tumour location on clinical outcome.

Expression of guanylyl cyclase C in tissue samples and the circulation of rectal cancer patients.

Guanylyl cyclase C (GCC) is a transmembrane surface receptor restricted to intestinal epithelial cells, from the duodenum to the rectum. We compared GCC expression in tumors and normal rectal tissues, and investigated the relation between GCC expression and metastasis and long-term survival of rectal cancer patients. Based on the UICC classification, 42 rectal cancer patients in this study were classified as stage I, 48 patients as stage II, and 90 patients as stage III. Overexpression of GCC was observed in 80 rectal tumors as compared to matched normal tissues, where no strong staining of GCC was observed. An association between GCC mRNA in the circulation and tumor emboli in vessels, CK20 mRNA, distant organ metastasis, and survival status was observed in 100 rectal cancer patients. Univariate Cox regression analysis indicated that tumor emboli in vessels, lymph node metastasis, mesenteric root lymph node metastasis and GCC mRNA correlated with 5-year disease-free survival (DFS); while lymph node metastasis, GCC mRNA, and CK20 mRNA strongly correlated with 5-year overall survival (OS). In a multivariate Cox regression model, GCC mRNA level and mesenteric root lymph node metastasis associated with DFS, while GCC mRNA levels associated with OS. Quantification of GCC expression in circulation is a valuable biomarker for assessing tumor burden and predicting outcome in rectal cancer patients.

Association of thymidylate synthase polymorphisms with the tumor response to preoperative chemoradiotherapy in rectal cancer: a systematic review and meta-analysis.

Preoperative chemoradiotherapy (pCRT) followed by surgery is currently the standard therapy for patients with locally advanced rectal cancer. It is very important to develop biomarkers to prior identify the patients who have a higher likelihood of responding to pCRT. Recently, a series of studies have been conducted to investigate the association of thymidylate synthase (TYMS) polymorphisms with the tumor response to pCRT in rectal cancer, but the results were not consistent and conclusive. In the present study, we performed a systematic literature search for relevant studies up to 30 March 2015 and conducted a meta-analysis to summarize and clarify the association between the TYMS polymorphisms and the tumor response to pCRT in rectal cancer. Finally, 7 studies containing 892 cases for TYMS 2R/3R polymorphism, 7 studies involving 715 cases for TYMS 1494del6 polymorphism and 6 studies containing 616 cases for TYMS 5' untranslated region (UTR) expression allele polymorphism were analyzed in the meta-analysis. The results suggested that TYMS 2R/3R was associated with the response and the patients with 2R/2R or 2R/3R genotype with rectal cancer might benefit more from pCRT than others. On the contrary, neither 1494del6 nor 5'UTR expression allele polymorphisms was associated with the response to pCRT.

Predictive value of vrk 1 and 2 for rectal adenocarcinoma response to neoadjuvant chemoradiation therapy: a retrospective observational cohort study.

BACKGROUND: Neoadjuvant chemoradiotherapy (NACRT) followed by surgical resection is the standard therapy for locally advanced rectal cancer. However, tumor response following NACRT varies, ranging from pathologic complete response to disease progression. We evaluated the kinases VRK1 and VRK2, which are known to play multiple roles in cellular proliferation, cell cycle regulation, and carcinogenesis, and as such are potential predictors of tumor response and may aid in identifying patients who could benefit from NACRT. METHODS: Sixty-seven pretreatment biopsies were examined for VRK1 and VRK2 expression using tissue microarrays. VRK1 and VRK2 Histoscores were combined by linear addition, resulting in a new variable designated as "composite score", and the statistical significance of this variable was assessed by univariate and multivariate logistic regression. The Hosmer-Lemeshow goodness-of-fit test and area under the ROC curve (AUC) analysis were carried out to evaluate calibration and discrimination, respectively. A nomogram was also developed. RESULTS: Univariate logistic regression showed that tumor size as well as composite score were statistically significant. Both variables remained significant in the multivariate analysis, obtaining an OR for tumor size of 0.65 (95 % CI, 0.45-0.94; p = 0.021) and composite score of 1.24 (95 % CI, 1.07-1.48; p = 0.005). Hosmer-Lemeshow test showed an adequate model calibration (p = 0.630) and good discrimination was also achieved, AUC 0.79 (95 % CI, 0.68-0.90). CONCLUSIONS: This study provides novel data on the role of VRK1 and VRK2 in predicting tumor response to NACRT, and we propose a model with high predictive ability which could have a substantial impact on clinical management of locally advanced rectal cancer.

Genetic polymorphisms in 5-Fluorouracil-related enzymes predict pathologic response after neoadjuvant chemoradiation for rectal cancer.

BACKGROUND: Many patients with rectal cancer undergo preoperative neoadjuvant chemoradiation, with approximately 70% exhibiting pathologic downstaging in response to treatment. Currently, there is no accurate test to predict patients who are likely to be complete responders to therapy. 5-Fluorouracil is used regularly in the neoadjuvant treatment of rectal cancer. Genetic polymorphisms affect the activity of thymidylate synthase, an enzyme involved in 5-Fluorouracil metabolism, which may account for observed differences in response to neoadjuvant treatment between patients. Detection of genetic polymorphisms might identify patients who are likely to have a complete response to neoadjuvant therapy and perhaps allow them to avoid operation. METHODS: DNA was isolated from whole blood taken from patients with newly diagnosed rectal cancer who received neoadjuvant therapy (n = 50). Response to therapy was calculated with a tumor regression score based on histology from the time of operation. Polymerase chain reaction was performed targeting the promoter region of thymidylate synthase. Polymerase chain reaction products were separated using electrophoresis to determine whether patients were homozygous for a double-tandem repeat (2R), a triple-tandem repeat (3R), or were heterozygous (2R/3R). A single nucleotide polymorphism, 3G or 3C, also may be present in the second repeat unit of the triple-tandem repeat allele. Restriction fragment length polymorphism assays were performed in patients with at least one 3R allele using HaeIII. RESULTS: Patients with at least 1 thymidylate synthase 3G allele were more likely to have a complete or partial pathologic response to 5-Fluorouracil neoadjuvant therapy (odds ratio 10.4; 95% confidence interval, 1.3-81.6; P = .01) than those without at least one 3G allele. CONCLUSION: Identification of rectal cancer patients with specific genetic polymorphisms in enzymes involved in 5-Fluorouracil metabolism seems to predict the likelihood of complete or partial pathologic response to preoperative neoadjuvant therapy.

Focal adhesion kinase: predictor of tumour response and risk factor for recurrence after neoadjuvant chemoradiation in rectal cancer.

Rectal cancer represents about 30% of colorectal cancers, being around 50% locally advanced at presentation. Chemoradiation (CRT) followed by total mesorectal excision is the standard of care for these locally advanced stages. However, it is not free of adverse effects and toxicity and the complete pathologic response rate is between 10% and 30%. This makes it extremely important to define factors that can predict response to this therapy. Focal adhesion kinase (FAK) expression has been correlated with worse prognosis in several tumours and its possible involvement in cancer radio- and chemosensitivity has been suggested; however, its role in rectal cancer has not been analysed yet. To analyse the association of FAK expression with tumour response to CRT in locally advanced rectal cancer. This study includes 73 patients with locally advanced rectal cancer receiving standard neoadjuvant CRT followed by total mesorectal excision. Focal adhesion kinase protein levels were immunohistochemically analysed in the pre-treatment biopsies of these patients and correlated with tumour response to CRT and patients survival. Low FAK expression was significantly correlated with local and distant recurrence (P = 0.013). Low FAK expression was found to be a predictive marker of tumour response to neoadjuvant therapy (P = 0.007) and patients whose tumours did not express FAK showed a strong association with lower disease-free survival (P = 0.01). Focal adhesion kinase expression predicts neoadjuvant CRT response in rectal cancer patients and it is a clinically relevant risk factor for local and distant recurrence.

Clinical features, endoscopic polypectomy and STK11 gene mutation in a nine-month-old Peutz-Jeghers syndrome Chinese infant.

AIM: To investigate multiple polyps in a Chinese Peutz-Jeghers syndrome (PJS) infant. METHODS: A nine-month-old PJS infant was admitted to our hospital for recurrent prolapsed rectal polyps for one month. The clinical characteristics, a colonoscopic image, the pathological characteristics of the polyps and X-ray images of the intestinal perforation were obtained. Serine threonine-protein kinase 11 (STK11) gene analysis was also performed using a DNA sample from this infant. RESULTS: Here we describe the youngest known Chinese infant with PJS. Five polyps, including a giant polyp of approximately 4 cm × 2 cm in size, were removed from the infant's intestine. Laparotomy was performed to repair a perforation caused by pneumoperitoneum. The pathological results showed that this child had PJS. Molecular analysis of the STK11 gene further revealed a novel frameshift mutation (c.64_65het_delAT) in exon 1 in this PJS infant. CONCLUSION: The appropriate treatment method for multiple polyps in an infant must be carefully considered. Our results also show that the STK11 gene mutation is the primary cause of PJS.

Hypoxia-Associated Marker CA IX Does Not Predict the Response of Locally Advanced Rectal Cancers to Neoadjuvant Chemoradiotherapy.

Hypoxia-associated proteome changes have been shown to be associated with resistance to chemo- and radiotherapy. Our study evaluated the role of the hypoxia-inducible (HIF)-1 target gene carbonic anhydrase (CA) IX in the prediction of the response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer (stages II and III). A total of 29 pretreatment biopsy specimens were stained for CA IX by immunohistochemistry, converted to digital images and evaluated in a quantitative fashion using image analysis software. Contrary to our expectations, a trend towards a correlation between better tumor regression (>50%) and higher expression of CA IX (p=0.056) was found. CA IX was also present more frequently in pathological tumor stage T1 (pT1) tumors (p=0.048). Conversely, no association with lymph node metastasis was identified. In conclusion, as a single marker, CA IX expression is not able to identify a hypoxia-related treatment resistant phenotype in rectal cancer.

Thymidine phosphorylase and hypoxia-inducible factor 1-α expression in clinical stage II/III rectal cancer: association with response to neoadjuvant chemoradiation therapy and prognosis.

The aim of this study was to determine whether pretreatment status of thymidine phosphorylase (TP), and hypoxia-inducible factor alpha (HIF-1α) could predict pathologic response to neoadjuvant chemoradiation therapy with oxaliplatin and capecitabine (XELOXART) and outcomes for clinical stage II/III rectal cancer patients. A total of 180 patients diagnosed with clinical stage II/III rectal cancer received XELOXART. The status of TP, and HIF-1α were determined in pretreatment biopsies by immunohistochemistry (IHC). Tumor response was assessed in resected regimens using the tumor regression grade system and TNM staging system. 5-year disease free survival (DFS) and 5-year overall survival (OS) were evaluated with the Kaplan-Meier method and were compared by the log-rank test. Over expression of TP and low expression of HIF-1α were associated with pathologic response to XELOXART and better outcomes (DFS and OS) in clinical stage II/III rectal cancer patients (P < 0.05). Our result suggested that pretreatment status of TP and HIF-1α were found to predict pathologic response and outcomes in clinical stage II/III rectal cancer received XELOXART. Additional well-designed, large sample, multicenter, prospective studies are needed to confirm the result of this study.

Acute liver failure and seizures as a consequence of regorafenib exposure in advanced rectal cancer.

BACKGROUND: Regorafenib is a multi-targeted tyrosine kinase inhibitor approved for use in refractory colorectal cancer. We report the first case of seizures secondary to acute liver failure, shortly after initiation of regorafenib in a patient with advanced rectal carcinoma. CASE PRESENTATION: A 64 year-old Caucasian female presented with confusion and generalized tonic-clonic seizures, 5 days after initiation of regorafenib for advanced rectal cancer. Investigations revealed significant elevations in bilirubin and alanine aminotransferase. No other cause for seizures and liver dysfunction were found. After interruption of regorafenib, no further seizures occurred, the symptoms of confusion resolved and liver function returned to normal. CONCLUSIONS: We report the first case of regorafenib-induced acute liver failure resulting in seizures. We suggest early monitoring for side effects, both clinically and biochemically after initiation of regorafenib.

Early increase in circulating carbonic anhydrase IX during neoadjuvant treatment predicts favourable outcome in locally advanced rectal cancer.

BACKGROUND: Locally advanced rectal cancer (LARC) comprises heterogeneous tumours with predominant hypoxic components. The hypoxia-inducible metabolic shift causes microenvironmental acidification generated by carbonic anhydrase IX (CAIX) and facilitates metastatic progression, the dominant cause of failure in LARC. METHODS: Using a commercially available immunoassay, circulating CAIX was assessed in prospectively archived serial serum samples collected during combined-modality neoadjuvant treatment of LARC patients and correlated to histologic tumour response and progression-free survival (PFS). RESULTS: Patients who from their individual baseline level displayed serum CAIX increase above a threshold of 224 pg/ml (with 96 % specificity and 39 % sensitivity) after completion of short-course neoadjuvant chemotherapy (NACT) prior to long-course chemoradiotherapy and definitive surgery had significantly better 5-year PFS (94 %) than patients with below-threshold post-NACT versus baseline alteration (PFS rate of 56 %; p < 0.01). This particular CAIX parameter, ΔNACT, was significantly correlated with histologic ypT0-2 and ypN0 outcome (p < 0.01) and remained an independent PFS predictor in multivariate analysis wherein it was entered as continuous variable (p = 0.04). CONCLUSIONS: Our results indicate that low ΔNACT, i.e., a weak increase in serum CAIX level following initial neoadjuvant treatment (in this case two cycles of the Nordic FLOX regimen), might be used as risk-adapted stratification to postoperative therapy or other modes of intensification of the combined-modality protocol in LARC. TRIAL REGISTRATION: ClinicalTrials.gov NCT00278694.

The rare BRAF VK600-601E mutation as a possible indicator of poor prognosis in rectal carcinoma ­ a report of a case.

BACKGROUND: The BRAF V600E mutation is reportedly associated with inferior survival among colon cancer patients. Here we report a patient with rectal cancer who carried the novel BRAF mutation VK600-601E, which has analogous molecular functions to those of the conventional BRAF mutation V600E, and may have potential as a prognostic marker for colorectal cancer (CRC). CASE PRESENTATION: The present 65-year-old male patient was diagnosed with recurrent rectal adenocarcinoma (stage II by AJCC TNM staging 7th edition) 14 months after surgery and was treated with modified FOLFOX6 (fluorouracil, leucovorin, and oxaliplatin), radiation, and FOLFIRI (fluorouracil, leucovorin, and irinotecan). The tumor progressed before further treatment could be initiated, resulting in death after 15 months. This survival period was similar to the median overall survival among patients with metastatic CRC and BRAF mutations who were treated with the FOLFIRI regimen with or without cetuximab. CONCLUSIONS: Thus, the BRAF VK600-601E mutation may lead to an aggressive clinical course in CRC patients suffering from rapid progression and potential resistance to multiple therapeutic modalities.

Tumor phosphatidylinositol 3-kinase signaling in therapy resistance and metastatic dissemination of rectal cancer: opportunities for signaling-adapted therapies.

Locally advanced rectal cancer (LARC) comprises heterogeneous tumors with predominant hypoxic components, a hallmark of the tumor microenvironment and determinant of resistance to cytotoxic therapies, local recurrence, and metastatic progression. A rational integration of molecularly targeted agents in established combined-modality treatment regimens may improve local and systemic disease control, but will require a clear definition of functional biomarkers for patient stratification. In a prospective study of LARC patients given neoadjuvant chemotherapy and radiation, we applied a kinase substrate array technology to analyze the patients' tumor biopsies sampled at the time of diagnosis, and observed that receptor tyrosine kinase activities integrated by high phosphatidylinositol 3-kinase signaling were correlated both with poor tumor response to the neoadjuvant treatment and adverse progression-free survival. Conceptually, the specific tumor signature of phosphatidylinositol 3-kinase signaling activity may point to actionable therapy targets in LARC patients with unfavorable disease features. Clinical trial registration number NCT00278694.

Phosphatidylinositol 3-kinase CB association with preoperative radiotherapy response in rectal adenocarcinoma.

AIM: To examine the correlation of phosphatidylinositol 3-kinase (PIK3) CB expression with preoperative radiotherapy response in patients with stage II/III rectal adenocarcinoma. METHODS: PIK3CB immunoexpression was retrospectively assessed in pretreatment biopsies from 208 patients with clinical stage II/III rectal adenocarcinoma, who underwent radical surgery after 30-Gy/10-fraction preoperative radiotherapy. The relation between PIK3CB expression and tumor regression grade, clinicopathological characteristics, and survival time was statistically analyzed. Western blotting and in vitro clonogenic formation assay were used to detect PIK3CB expression in four colorectal cancer cell lines (HCT116, HT29, LoVo, and LS174T) treated with 6-Gy ionizing radiation. Pharmacological assays were used to evaluate the therapeutic relevance of TGX-221 (a PIK3CB-specific inhibitor) in the four colorectal cancer cell lines. RESULTS: Immunohistochemical staining indicated that PIK3CB was more abundant in rectal adenocarcinoma tissues with poor response to preoperative radiotherapy. High expression of PIK3CB was closely correlated with tumor height (P < 0.05), ypT stage (P < 0.05), and high-degree tumor regression grade (P < 0.001). High expression of PIK3CB was a potential prognostic factor for local recurrence-free survival (P < 0.05) and metastasis-free survival (P < 0.05). High expression of PIK3CB was also associated with poor therapeutic response and adverse outcomes in rectal adenocarcinoma patients treated with 30-Gy/10-fraction preoperative radiotherapy. In vitro, PIK3CB expression was upregulated in all four colorectal cancer cell lines concurrently treated with 6-Gy ionizing radiation, and the PIK3CB-specific inhibitor TGX-221 effectively inhibited the clonogenic formation of these four colorectal cancer cell lines. CONCLUSION: PIK3CB is critically involved in response to preoperative radiotherapy and may serve as a novel target for therapeutic intervention.